Hello Alan (et al).
Thanks for the mention (your post #918) and thanks again for your efforts on my/our behalf. After 8 years of retirement I sometimes forget people have other things (meaningful things) to do every day.
Re: Paul Speltz interconnects – I swap between home- made with cat 5 cable; home-made with pure silver wire (with Teflon cover) with Eichmann connectors and Mapleshade pure copper foil “Ultrathin”. I have to be honest. I really cannot hear a difference so I’m not about to try anything else.
Re: existing crossover wire – The original wire appears to be long gone. I guess when the crossovers were re-done in the 90’s.
Re: Bi/Tri wiring. It would be interesting to tri-wire, at least initially with my new external crossovers to come. Also, one (of) the beauties of mono-block amplifiers is that they can be placed close to the speakers. Hence minimal speaker wire.
Re: SBA’s comment (post #914) regarding new woofers and baffle treatment for the 66’s. Firstly I look forward to your further coverage of the diffraction problem and secondly: is there a reasonably priced “better” 12in woofer replacement available for the 66’s??.
Reggie
Thanks for the mention (your post #918) and thanks again for your efforts on my/our behalf. After 8 years of retirement I sometimes forget people have other things (meaningful things) to do every day.
Re: Paul Speltz interconnects – I swap between home- made with cat 5 cable; home-made with pure silver wire (with Teflon cover) with Eichmann connectors and Mapleshade pure copper foil “Ultrathin”. I have to be honest. I really cannot hear a difference so I’m not about to try anything else.
Re: existing crossover wire – The original wire appears to be long gone. I guess when the crossovers were re-done in the 90’s.
Re: Bi/Tri wiring. It would be interesting to tri-wire, at least initially with my new external crossovers to come. Also, one (of) the beauties of mono-block amplifiers is that they can be placed close to the speakers. Hence minimal speaker wire.
Re: SBA’s comment (post #914) regarding new woofers and baffle treatment for the 66’s. Firstly I look forward to your further coverage of the diffraction problem and secondly: is there a reasonably priced “better” 12in woofer replacement available for the 66’s??.
Reggie
This has been a very enjoyable thread . It is almost like a fishing competition where naturally other fish will appear . To understand the Ditton 66 ( Thames Ditton Surrey , also called Rola , Celestion ) it is useful to know what was going on in the river so to speak . Some see the Isobarik loading and ABR as valiant attempts to do a little better . My experience with ABR is rather good . The Klipsche Forte looks to fail before it begins . Not so , it is rather good . I owned a pair Dynaco A25 ( ? ) . There had resistive port loading as did Proac ( CELEF , half Celestion , half KEF ) . Royd had a variation of port loading which I wish had come to production . Two identical frequency resonant port arrangements where the tubes were different lengths and diameter I believe ? The net effect was to reduce port turbulence and I suspect Q .
KEF had something a bit like Isobarik in the 107's . Strangely for them paper cones . Sadly when a company tries harder people show less interest than would seem logical . I can only imagine the KEF followers didn't approve . The KEF CUBE active EQ device might have been the reason . In the words of the KEF Rep the EQ box was KEF and KEF are not amplifier people in the eyes of the buyer . The 105 was better received , although to me out of Concerto and 107 was my third choice . The B&W 801 was I suspect hatched out of seeing KEF 105 .
I liked the idea of blocking off the ABR . Two speakers for the price of one . How like the Ditton 44 I wonder ?
We had this with British motorcycles . BSA Norton , AJS-Matchless , Royal Enfield .Seemingly as different as chalk and cheese to their supporters . In truth all clones of the Triumph twin ( which was derived from a Riley Pathfinder engine , and back into Daimler Dart V8 ) . Same river really .
The standard solution to diffraction was to put the unit in a glass sphere ( a light fitting ) or better . A friend has done this with his Leak speakers . As the 12 inch bass unit is almost a sub woofer it presents less problems than expected with integration . This has progressed to an open back design with no parallel sides . Other speakers had the unit raised up on a shaped step . 105 being the first mold breaker ( also Leak ) .
KEF had something a bit like Isobarik in the 107's . Strangely for them paper cones . Sadly when a company tries harder people show less interest than would seem logical . I can only imagine the KEF followers didn't approve . The KEF CUBE active EQ device might have been the reason . In the words of the KEF Rep the EQ box was KEF and KEF are not amplifier people in the eyes of the buyer . The 105 was better received , although to me out of Concerto and 107 was my third choice . The B&W 801 was I suspect hatched out of seeing KEF 105 .
I liked the idea of blocking off the ABR . Two speakers for the price of one . How like the Ditton 44 I wonder ?
We had this with British motorcycles . BSA Norton , AJS-Matchless , Royal Enfield .Seemingly as different as chalk and cheese to their supporters . In truth all clones of the Triumph twin ( which was derived from a Riley Pathfinder engine , and back into Daimler Dart V8 ) . Same river really .
The standard solution to diffraction was to put the unit in a glass sphere ( a light fitting ) or better . A friend has done this with his Leak speakers . As the 12 inch bass unit is almost a sub woofer it presents less problems than expected with integration . This has progressed to an open back design with no parallel sides . Other speakers had the unit raised up on a shaped step . 105 being the first mold breaker ( also Leak ) .
Update on USB audio interface & pair of 66's: $1225
I now have a 2nd hand M-Audio 'USB Audiophile' audio interface for future spkr testing. Not tried it yet but it has reasonably good specs and zero latency apparently.
A Sydney, Australia pair of 66's just went for AUD1225 on ebay: Item 221147740783
I now have a 2nd hand M-Audio 'USB Audiophile' audio interface for future spkr testing. Not tried it yet but it has reasonably good specs and zero latency apparently.
A Sydney, Australia pair of 66's just went for AUD1225 on ebay: Item 221147740783
Wow! I've been browsing as a silent listener for a while now, and I am amazed at the knowledge, talent, and good will on this forum. It is the reason I joined back when I was waiting to get my Celestion 66s. Now I have them and I am sad to say, I am finding them harsh to my ears. Having read this thread, I am really not worried, as I believe I will fix that harshness either through recapping/restoring the 66s, or by restoring my MAC1900. As a temporary fix, I have thrown in an EQ to smooth out the harshness.
Soon the snow will be falling, and I will have time to start really digging into these babies. In the meantime, I have been given a dead NAD 7240PE to practice with.
SBA, the 4100 is a really nice beast. If I find one, I will definitely jump at it! I find myself browsing kijiji daily with the hopes of finding new treasures.
Alan, I will definitely be taking pictures as I open up the 66s. In talking with the original owner, he thinks he left the original wiring and definitely did replace the caps with electrolytics. He said 22 years ago he knew a lot less than he knows now. He does regret putting them in.
I will be following your suggestions on this thread. I am really looking forward to it. I have never learned so much theory on one thread before. Thanks for everything!
Soon the snow will be falling, and I will have time to start really digging into these babies. In the meantime, I have been given a dead NAD 7240PE to practice with.
SBA, the 4100 is a really nice beast. If I find one, I will definitely jump at it! I find myself browsing kijiji daily with the hopes of finding new treasures.
Alan, I will definitely be taking pictures as I open up the 66s. In talking with the original owner, he thinks he left the original wiring and definitely did replace the caps with electrolytics. He said 22 years ago he knew a lot less than he knows now. He does regret putting them in.
I will be following your suggestions on this thread. I am really looking forward to it. I have never learned so much theory on one thread before. Thanks for everything!
Technical , Music recordings and other comments ; Diffraction
G'day reggie , and all interested readers here ,
I'll post some replies to reggie from #905 on page 91 , and also from #921 on this page , and include some other points relevant to upgrades.
1(a)- it seems your brain/hearing does not give priority to Polarity.
Be grateful for that , because for some listeners it is a priority ,
however your brain/ear will likely have another type of priority that some of us do not have.
I will try to discern what it may be from your posts , and hopefully address it in replies.
Celestion's original plot of Amplitude versus Frequency for the 66 shows a slightly lower output of about -2dB , { if I am remembering correctly } ,
for Treble from their HF2000 relative to upper midrange output from the mid-dome ,
and that is in accord with the Listening Test comments made by the "High Fidelity" magazine reviewer.
The SEAS tweeter I have been recomending will not be -2dB with relative to the mids , nor will Hiquphon OW1 ,
and your Hiquphon OW2 will have higher output than the mid-dome , but we can get it to match closer in level.
*
1(b)- I recommend to DennyG and sba , and to TechnoDweeb if you are intending to do some measurements ,
that you go to :
David Ralph's Speaker Pages
and read the four articles in the "Diffraction" section if you have not yet done so.
There is some other useful stuff in Dave's pages also , and maybe more as I have not had time to read it all yet ,
but thanks to reggie for posting about this web-site !
*
2(a)- to be continued at a later time.
*
2(b)- (i) and (ii) - Boccherini was a Cellist , thus if the two recordings you have are of good audio quality they will likely be useful to evaluate the relative levels and quality from the mid-domes versus the lower midrange from the woofers , as Cello covers all of the midrange , and in fact covers from upper bass to upper mids well.
The other instruments on these recordings , if well balanced in the recordings , will give some references around the complete frequency range of the 66.
(iii) - Pergolesi's "Stabat Mater" is excellent music to use to assess from upper bass through to treble with the instruments , and the two vocalists cover from lower to upper midrange , and a little into the treble for the soprano singer ...
and she will likely be Gillian Fisher on this recording reggie !
if it is the one on Hyperion label with the Kings Consort and Robert King.
The Hyperion recording has very good audio quality.
Gillian Welch , { if spelling is not Welsh } , is a USA singer of a roots type of folk and country music , sort of a development of Appalacian music and related { used to be called Hillbilly music years ago ! } and which is not highly commercialised Nashville C&W ... thankfully !
I have her first three albums , and all are well enough recorded to be useful to assess the relative quality of output from loudspeakers.
*
(3)- refer to about the Cello recordings above.
*
(4)- The upper bass problem may be owing to how you have blocked off the ABR/passive radiator.
Is it still in the cabinet , and with some thing fixed over its front ? ,
or , is it removed and something fixed into the open space ,
and if this latter then how thick and stiff is the new fixing and how well sealed so no air gaps around it ?
*
New point: (9)- so you have no ABRs , new tweeters , think you may change the mid-domes , and later ask in #921 about alternate woofers ...
what is it that will still be a Celestion 66 ?
You likely do not need alternate woofers - are yours in any way damaged ?
*
Can you attach the entire "High Fidelity" magazine review here , including any plots and technical measurements ? ,
or if not , then please what year/month/volume or issue number is it , in the event someone may be able to find a copy ?
G'day reggie , and all interested readers here ,
I'll post some replies to reggie from #905 on page 91 , and also from #921 on this page , and include some other points relevant to upgrades.
*
1(a)- it seems your brain/hearing does not give priority to Polarity.
Be grateful for that , because for some listeners it is a priority ,
however your brain/ear will likely have another type of priority that some of us do not have.
I will try to discern what it may be from your posts , and hopefully address it in replies.
Celestion's original plot of Amplitude versus Frequency for the 66 shows a slightly lower output of about -2dB , { if I am remembering correctly } ,
for Treble from their HF2000 relative to upper midrange output from the mid-dome ,
and that is in accord with the Listening Test comments made by the "High Fidelity" magazine reviewer.
The SEAS tweeter I have been recomending will not be -2dB with relative to the mids , nor will Hiquphon OW1 ,
and your Hiquphon OW2 will have higher output than the mid-dome , but we can get it to match closer in level.
*
1(b)- I recommend to DennyG and sba , and to TechnoDweeb if you are intending to do some measurements ,
that you go to :
David Ralph's Speaker Pages
and read the four articles in the "Diffraction" section if you have not yet done so.
There is some other useful stuff in Dave's pages also , and maybe more as I have not had time to read it all yet ,
but thanks to reggie for posting about this web-site !
*
2(a)- to be continued at a later time.
*
2(b)- (i) and (ii) - Boccherini was a Cellist , thus if the two recordings you have are of good audio quality they will likely be useful to evaluate the relative levels and quality from the mid-domes versus the lower midrange from the woofers , as Cello covers all of the midrange , and in fact covers from upper bass to upper mids well.
The other instruments on these recordings , if well balanced in the recordings , will give some references around the complete frequency range of the 66.
(iii) - Pergolesi's "Stabat Mater" is excellent music to use to assess from upper bass through to treble with the instruments , and the two vocalists cover from lower to upper midrange , and a little into the treble for the soprano singer ...
and she will likely be Gillian Fisher on this recording reggie !
if it is the one on Hyperion label with the Kings Consort and Robert King.
The Hyperion recording has very good audio quality.
Gillian Welch , { if spelling is not Welsh } , is a USA singer of a roots type of folk and country music , sort of a development of Appalacian music and related { used to be called Hillbilly music years ago ! } and which is not highly commercialised Nashville C&W ... thankfully !
I have her first three albums , and all are well enough recorded to be useful to assess the relative quality of output from loudspeakers.
*
(3)- refer to about the Cello recordings above.
*
(4)- The upper bass problem may be owing to how you have blocked off the ABR/passive radiator.
Is it still in the cabinet , and with some thing fixed over its front ? ,
or , is it removed and something fixed into the open space ,
and if this latter then how thick and stiff is the new fixing and how well sealed so no air gaps around it ?
*
New point: (9)- so you have no ABRs , new tweeters , think you may change the mid-domes , and later ask in #921 about alternate woofers ...
what is it that will still be a Celestion 66 ?
You likely do not need alternate woofers - are yours in any way damaged ?
*
Can you attach the entire "High Fidelity" magazine review here , including any plots and technical measurements ? ,
or if not , then please what year/month/volume or issue number is it , in the event someone may be able to find a copy ?
Last edited:
Well, It looks like I will be starting the 66 recap project soon. First I need to resolve a problem on my MAC1900 of the left channel shutting down. Is there a thread here on troubleshooting a MAC1900? I suspect that the 1900 may force me to go all out now. Doesn't make sense to fix one problem only to get hit with another shortly later, and the age of the MAC1900 is around 1973/74 timeframe. I opened it up last night and was really impressed with the quality of workmanship inside this beast. It is rather ironic, as the left channel cut out after a brief crackling, just before I left home to pick up a pair of gorgeous Celestion Ditton 44s with nicely sun bleached rosewood enclosures. After I reseated the MACs cards and inspected for obvious problems, I ABed the 44 and the 66, and then the 44 and my Tannoy MX4s. The 44s won the comparisons, and that included having my daughter and houseguest as unbiased listeners. Grandson said too loud, and covered up his ears.
A bit on my background. I studied industrial controls and ended up with a 23 career with Digital Equipment Corp, Compaq Computers, and then finally another company that shall remain un-named. I have worked extensively with oscilloscopes at my first job in the R&D department of a small CAD/CAM company in the mid 80's. We designed, built, and fixed custom boards to enhance the throughput of the CAD/CAM systems, so I leaned to wire-wrap, troubleshoot, and repair down to the chip level. From there, I went to Digital field service, where I worked on PDPs, VAXes, and Alpha servers along with all types of tape drives from the large 9 track drives utilizing to 4 ml DAT drives. However, I have not touched anything like this since 1999. As you can see, I am definitely not an analog audio person. It is a whole new world for me. I did design and build a pair of bass reflex speaker cabinets in the late 70s, and they sounded pretty good on my Marantz 2235(?), I think. I am certain I will need help as I walk through this process.
Fortunately, I still have my Weller soldering station, Tektronix oscilloscope, and a couple of Fluke multimeters (models 73 and 75), as well as the soldering and desoldering skills and techniques required to repair temperature sensitive IC chips.
I digress. My goal is to get the MAC working so I can run the 44s on it, and that will allow me to listen to beautiful music as I work on the 66s. I will be taking lots of pictures, which I will include either on this thread, or a new one if I need to. This has become an obsession for me. I am also enjoying the people I've been meeting in my pursuit of this passion. I've met 3 really nice guys with the same passion as mine, and surprisingly enough, the same appreciation to similar music.
As I type this message, the MAC 1900 is drifting a little. Now the right channel is drifting in and out. Should I stop playing it? Do you think the 44s are overdriving this receiver? I ran it with the 66s for well over a month with no issues, but maybe this is just the symptom of the problem. I suspect I may have a transistor on it's last legs. Need to get out the theory books on troubleshooting transistors...
A bit on my background. I studied industrial controls and ended up with a 23 career with Digital Equipment Corp, Compaq Computers, and then finally another company that shall remain un-named. I have worked extensively with oscilloscopes at my first job in the R&D department of a small CAD/CAM company in the mid 80's. We designed, built, and fixed custom boards to enhance the throughput of the CAD/CAM systems, so I leaned to wire-wrap, troubleshoot, and repair down to the chip level. From there, I went to Digital field service, where I worked on PDPs, VAXes, and Alpha servers along with all types of tape drives from the large 9 track drives utilizing to 4 ml DAT drives. However, I have not touched anything like this since 1999. As you can see, I am definitely not an analog audio person. It is a whole new world for me. I did design and build a pair of bass reflex speaker cabinets in the late 70s, and they sounded pretty good on my Marantz 2235(?), I think. I am certain I will need help as I walk through this process.
Fortunately, I still have my Weller soldering station, Tektronix oscilloscope, and a couple of Fluke multimeters (models 73 and 75), as well as the soldering and desoldering skills and techniques required to repair temperature sensitive IC chips.
I digress. My goal is to get the MAC working so I can run the 44s on it, and that will allow me to listen to beautiful music as I work on the 66s. I will be taking lots of pictures, which I will include either on this thread, or a new one if I need to. This has become an obsession for me. I am also enjoying the people I've been meeting in my pursuit of this passion. I've met 3 really nice guys with the same passion as mine, and surprisingly enough, the same appreciation to similar music.
As I type this message, the MAC 1900 is drifting a little. Now the right channel is drifting in and out. Should I stop playing it? Do you think the 44s are overdriving this receiver? I ran it with the 66s for well over a month with no issues, but maybe this is just the symptom of the problem. I suspect I may have a transistor on it's last legs. Need to get out the theory books on troubleshooting transistors...
That's a bummer technodweeb.
You can get help at Terry Dewick's MAC thread --
McIntosh - Hints and Kinks - AudioKarma.org Home Audio Stereo Discussion Forums
regards
You can get help at Terry Dewick's MAC thread --
McIntosh - Hints and Kinks - AudioKarma.org Home Audio Stereo Discussion Forums
regards
Thanks sba!
I've just finished going through the whole thread. Tons of information on it.
Here is what I think has happened to me. The MAC1900 is able to drive 4 to 16 ohm loads, however I have always been nervous about the 4 ohm loads after reading a few comments on threads. But I've been even more nervous about drive a 4 ohm load on A, and an 8 ohm load on B.
Friday night, I had forgotten both A and B on, and I think I was driving mixed loads. The MAC shutdown the left channel to protect it after driving both loads for about an hour. Last night, I was reorganizing my set up for the 44s, and I had a flakey contact on ground of the right speaker, and I think the MAC shutdown that channel as a result. After I had completed the new set up, I have been running the MAC continuously with no problems. Mind you I suspect that some of the components are at borderline of tolerances so it doesn't take much to push it past, and initiate circuit protection. If I am right, it seems the protection circuitry actually still works!
Now hopefully, I have some time to play with the 66s. Stay tuned...
I've just finished going through the whole thread. Tons of information on it.
Here is what I think has happened to me. The MAC1900 is able to drive 4 to 16 ohm loads, however I have always been nervous about the 4 ohm loads after reading a few comments on threads. But I've been even more nervous about drive a 4 ohm load on A, and an 8 ohm load on B.
Friday night, I had forgotten both A and B on, and I think I was driving mixed loads. The MAC shutdown the left channel to protect it after driving both loads for about an hour. Last night, I was reorganizing my set up for the 44s, and I had a flakey contact on ground of the right speaker, and I think the MAC shutdown that channel as a result. After I had completed the new set up, I have been running the MAC continuously with no problems. Mind you I suspect that some of the components are at borderline of tolerances so it doesn't take much to push it past, and initiate circuit protection. If I am right, it seems the protection circuitry actually still works!
Now hopefully, I have some time to play with the 66s. Stay tuned...
types of Felt and application to 66 ; Mac 1900 with Celestions
Hi TechnoDweeb ,
you are right to be cautious about using your Mac 1900 with 4 ohms to one set of outputs when simultaneously 8 ohms to the other set of outputs.
I would not do it.
I do not have a McIntosh amplifier , though I know these are very good amplifiers ,
however almost no amplifiers will drive a pair of 4 ohm l'speakers simultaneously with another pair of l'speakers of any impedance.
If you need to drive 4 loudspeakers simultaneously than buy a Krell amp ,
or a dedicated 4 channel amplifier.
Celestion 44 and 66 both vary in load between 4 and 8 ohms , and both have fairly steep phase angles over parts of their impedance.
-{see the Impedance plots that some participants have posted in this thread}-
When high phase angles in the impedance the amp has to supply greater voltage and current than when low phase angle/fairly flat impedance ,
thus amp is working hard enough driving a 44 or 66 pair without adding another pair !
From your description of their sound it seems the caps in your 44s are in OK condition still ,
but I would soon replace the 24uF or 30uF -{whichever is in the midrange filter}- soon ,
because if it starts to leak significantly the mid driver will be damaged.
There is a Celestion 44 thread I have posted a lot in here:
Crossover nightmare!!!!!!!
started by:
lorienblack
*** *** *** *** ***
For Diffraction control , and following the information posted by reggie and the Link I posted above in #925 , look now at:
SAE & Sheet Felt
for technical specifications about Felt.
The relevant specifications for sound absorption are:
Wool Content - preferably at least 95%
Air Perm - the highest number possible
Noise Reduction Coef - the highest number possible , and note that this will always be less than 1 , it will be a decimal , eg: 0.52 .
Ignore all the other specifications listed , as those are for other applications.
SAE specification felts are best , buy at least SAE F-5 , but F-10 is much better.
-{David Ralph used either F-11 or F-13 as he couldn't get F-10 , but those are less wool % and not as good for what we are doing}-
F-10 is more expensive but is worth it.
If you cannot find or afford SAE felt , then buy "Industrial" felt that has an S rating.
S1 is the softest and most absorbent for sound , and is 95% wool.
If you can only buy unspecified felts then buy Soft or Very Soft , and not Medium , Firm , Hard grades ,
and ask for 100% wool.
Composites , usually Wool + Rayon , even if Soft grade , are not as good for what we are doing .
-{ but they could be used inside enclosures that use later era Plastic cone drivers }-.
Unspecified felts are usually known as Craft Felt , and are available from Craft stores and Haberdashery stores ,
but usually these are no thicker than 2mm , which is OK to soft roll up to stick under the top lip of the 66 enclosure , but not suitable for the David Ralph described applications.
You may find a Soft felt sold as Saddle Felt elsewhere , but I do not know how thick those are ,
and most are likely to be equivalent to Medium or Firm grades.
More attractive to look at than what David Ralph has pictured , and somewhat better for sound absorption ,
is to cut a Star shape out and use the remaining piece around the tweeter.
A 6 point star cut-out is best , but a 5 point will suffice.
4 points are not sufficient.
The inner point of the felt frame must be at the Top and pointing down to the tweeter , and it can go over the tweeter flange to almost to the dome.
Alternately , cut a Star cut-out for the top , and a zig-zag of Acute angles down the 2 sides to make a frame to go around tweeter and mid-dome with no felt in between the drivers.
Acute angles present much better surfaces for absorption than 90 degree angles and Obtuse angles.
If you have a large piece of felt it can cover to almost the edges of the front panel to meet the raised edge section.
Suitable thicknesses are available , but you will likely have to buy Mail-order.
I have to go now - will return when time available.
Hi TechnoDweeb ,
you are right to be cautious about using your Mac 1900 with 4 ohms to one set of outputs when simultaneously 8 ohms to the other set of outputs.
I would not do it.
I do not have a McIntosh amplifier , though I know these are very good amplifiers ,
however almost no amplifiers will drive a pair of 4 ohm l'speakers simultaneously with another pair of l'speakers of any impedance.
If you need to drive 4 loudspeakers simultaneously than buy a Krell amp ,
or a dedicated 4 channel amplifier.
Celestion 44 and 66 both vary in load between 4 and 8 ohms , and both have fairly steep phase angles over parts of their impedance.
-{see the Impedance plots that some participants have posted in this thread}-
When high phase angles in the impedance the amp has to supply greater voltage and current than when low phase angle/fairly flat impedance ,
thus amp is working hard enough driving a 44 or 66 pair without adding another pair !
From your description of their sound it seems the caps in your 44s are in OK condition still ,
but I would soon replace the 24uF or 30uF -{whichever is in the midrange filter}- soon ,
because if it starts to leak significantly the mid driver will be damaged.
There is a Celestion 44 thread I have posted a lot in here:
Crossover nightmare!!!!!!!
started by:
lorienblack
*** *** *** *** ***
For Diffraction control , and following the information posted by reggie and the Link I posted above in #925 , look now at:
SAE & Sheet Felt
for technical specifications about Felt.
The relevant specifications for sound absorption are:
Wool Content - preferably at least 95%
Air Perm - the highest number possible
Noise Reduction Coef - the highest number possible , and note that this will always be less than 1 , it will be a decimal , eg: 0.52 .
Ignore all the other specifications listed , as those are for other applications.
SAE specification felts are best , buy at least SAE F-5 , but F-10 is much better.
-{David Ralph used either F-11 or F-13 as he couldn't get F-10 , but those are less wool % and not as good for what we are doing}-
F-10 is more expensive but is worth it.
If you cannot find or afford SAE felt , then buy "Industrial" felt that has an S rating.
S1 is the softest and most absorbent for sound , and is 95% wool.
If you can only buy unspecified felts then buy Soft or Very Soft , and not Medium , Firm , Hard grades ,
and ask for 100% wool.
Composites , usually Wool + Rayon , even if Soft grade , are not as good for what we are doing .
-{ but they could be used inside enclosures that use later era Plastic cone drivers }-.
Unspecified felts are usually known as Craft Felt , and are available from Craft stores and Haberdashery stores ,
but usually these are no thicker than 2mm , which is OK to soft roll up to stick under the top lip of the 66 enclosure , but not suitable for the David Ralph described applications.
You may find a Soft felt sold as Saddle Felt elsewhere , but I do not know how thick those are ,
and most are likely to be equivalent to Medium or Firm grades.
More attractive to look at than what David Ralph has pictured , and somewhat better for sound absorption ,
is to cut a Star shape out and use the remaining piece around the tweeter.
A 6 point star cut-out is best , but a 5 point will suffice.
4 points are not sufficient.
The inner point of the felt frame must be at the Top and pointing down to the tweeter , and it can go over the tweeter flange to almost to the dome.
Alternately , cut a Star cut-out for the top , and a zig-zag of Acute angles down the 2 sides to make a frame to go around tweeter and mid-dome with no felt in between the drivers.
Acute angles present much better surfaces for absorption than 90 degree angles and Obtuse angles.
If you have a large piece of felt it can cover to almost the edges of the front panel to meet the raised edge section.
Suitable thicknesses are available , but you will likely have to buy Mail-order.
I have to go now - will return when time available.
Last edited:
Thanks for the information Alan!
Things have changed here again. This will be my last posting on the Ditton 66 thread, but not on the Ditton 44 thread. I found a fully restored Sansui 9090 last Saturday, and traded my 66s for it and some cash. I also bought a pair of Kef Concerto's on Sunday with the cash. I was having buyers remorse because I felt I had spent way more than I wanted to on the 66s. This trade leaves me feeling better about things. Now I have enough clean power for when I want to crank it up. I'm getting closer to the sound I am looking for. And I look forward to working on the 44s.
My only regret is that I never did open up the 66s, but I did get some pictures of them. I think I said they were brownies before, but they are actually blackies.
One last point of interest is that the 44s have felt around the tweeter. I wonder if putting felt around the 66 tweeters would have sweetened them up?
Cheers,
Byron
Things have changed here again. This will be my last posting on the Ditton 66 thread, but not on the Ditton 44 thread. I found a fully restored Sansui 9090 last Saturday, and traded my 66s for it and some cash. I also bought a pair of Kef Concerto's on Sunday with the cash. I was having buyers remorse because I felt I had spent way more than I wanted to on the 66s. This trade leaves me feeling better about things. Now I have enough clean power for when I want to crank it up. I'm getting closer to the sound I am looking for. And I look forward to working on the 44s.
My only regret is that I never did open up the 66s, but I did get some pictures of them. I think I said they were brownies before, but they are actually blackies.
One last point of interest is that the 44s have felt around the tweeter. I wonder if putting felt around the 66 tweeters would have sweetened them up?
Cheers,
Byron
Felt for Diffraction control , continued ...
Continuing from my Post #929 on Page 93:
SAE specification felts are known as Engineering Felts.
Industrial felts are known as Technical Felts.
Both types are available in various thicknesses ,
and in various Sheet or Roll sizes , and not all suppliers will have all options of sizes , so you will have to search the internet or a printed Trade Directory for your area.
I drew some options to scale for the 66 baffle with regard to the drivers' sizes and spacings.
I do not have access to a scanner to post my drawings here , so I will attempt a diagram using several keyboard key symbols , as follows:
# for the extended wood of the Top of Cabinet Lip ,
0 shows the inner edge of the vertical recessed strip -{ only Left side will be shown } ,
* for Felt covered area , including where the felt overlaps the chassis of the driver's mounting ,
X to form the circles that are the edge of the drivers' chassis ,
and for the clamps that hold the drivers to the baffle.
x for the flat sections of the drivers' chassis and the surfaces of the domes ,
O for the circumferences of the domes.
Note: there is no clamp shown at the top of the tweeter chassis because the felt is to cover over that clamp.
o is for uncovered areas of the baffle , because the blanks spacer bar does not save to completion of posting.
Edge details for the Right side are not shown , because the small typing box is not wide enough for me to calculate easily how to include the Right side ,
however the Right side is to be the mirror image of the shown Left side.
I do not know what caused the wavey line down through the Right area of the diagram ... ?
_________________________________________________________________
####################################################
####################################################
0*********************************************************
0*********************************************************
0**oooo***************************************************
0***oooooooooooo*******************************************
0****ooooooooooooooooooooooo************************
0*****oooooooooooooooooooooooooooooooX*****X
0******oooooooooooooooooooooooooooXxxxxxx*xxxxxX
0*******ooooooooooooooooooooooooXxxxxxOxxxxxOxxxxX
0********ooooooooooooooooooooooXxxxxxOxxxxxxxOxxxxX
0*******ooooooooooooooooooooooooXxxxxxOxxxxxOxxxxX
0******oooooooooooooooooooooooooooXxxxxxO_OxxxxxX
0*****oooooooooooooooooooooooooooXoooXxxxxxxxXoooX
0****ooooooooooooooooooooooooooooooooooooX
0***oooooooooooooooooooooooooooooooooooooo
0***oooooooooooooooooooooooooooooooooooooo
0****oooooooooooooooooooooooooooooooooooXXX
0*****ooooooooooooooooooooXooooooooXxxxxxxxxxxxxxXoooooooX
0******oooooooooooooooooooooXooXxxxxxxxxxxxxxxxxxxxxxXooX
0*******oooooooooooooooooooXxxXxxxxxxxxxxxxxxxxxxxxxxxxX
0********ooooooooooooooooXxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxX
0*******ooooooooooooooooXxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxX
0******ooooooooooooooooXxxxxxxxxxxxxxxxxxxxOOxxxxxxxxxxxxxxxxxX
0*****ooooooooooooooooXxxxxxxxxxxxxxxOxxxxxxxxxxxOxxxxxxxxxxxxxX
0****ooooooooooooooooXxxxxxxxxxxxxxOxxxxxxxxxxxxxxxxOxxxxxxxxxxxX
0***oooooooooooooooooXxxxxxxxxxxxxOxxxxxxxxxxxxxxxxxxOxxxxxxxxxxxX
0***oooooooooooooooooXxxxxxxxxxxxxOxxxxxxxxxxxxxxxxxxOxxxxxxxxxxxX
0****ooooooooooooooooXxxxxxxxxxxxxxOxxxxxxxxxxxxxxxxOxxxxxxxxxxxX
0*****ooooooooooooooooXxxxxxxxxxxxxxxOxxxxxxxxxxxxOxxxxxxxxxxxxX
0******ooooooooooooooooXxxxxxxxxxxxxxxxxxxxOOxxxxxxxxxxxxxxxxX
0*******oooooooooooooooooXxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxX
0********ooooooooooooooooooXxxxxxxxxxxxxxxxxxxxxxxxxxxxxxX
0*******ooooooooooooooooooXoooXxxxxxxxxxxxx*xxxxxxxxxxXoooX
0******ooooooooooooooooooXooooooooooooo*****oooooooooooooX
0*****ooooooooooooooooooooooooooooo*************
0****oooooooooooooooooooooooo***********************
0***ooooooooooooooooooooo********************************
0****ooooooooooooooo***************************************
0*****oooooooo*********************************************
0******o**************************************************
0*************************************O*******************
0**********************OxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxO*****
0*****************OxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxO
0**************O
0***********O
0*********O
0*******O
0*****O
0****O
0***O
0**O
0*O
0O
0<------------------------------this part circular space is the woofer--->
0O
_________________________________________________________________
The diagram is not exactly to Scale , because it was too difficult to get such to work with the between lines spacings , etc ...
No felt is needed below the woofer , as it would not be effective there.
For most of the area to be covered quarter inch thick felt is sufficient if it is very soft and porous ,
though half inch thick will produce somewhat better results.
For the area above the tweeter to the top wooden lip use 1 inch thick felt ,
or cut 2 pieces from half inch and stack them , because ALL the underside of that wood must be covered ,
or there will be destructive reflections.
To stick these two pieces together apply Fabric Adhesive to the back half only of the surfaces ,
because if there is adhesive solid at the front edge the sound waves will not absorb as well as possible.
The felt here must be placed so that it has open cut edges facing downwards for there to be absorption of sound from the tweeter.
In #929 I stated to cut Acute angles for the zig-zag side of baffle felt.
That will not work well with this narrow baffle , so cut Obtuse angles , as shown.
The felt above the tweeter , and between the mid-dome and woofer , can be cut to an obtuse angle apex , or slightly curved around the apex.
Do whichever you prefer the look of.
For all the felt cuts observe the following three conditions , or there will be some destructive reflections because the felt is not completely absorptive of sound waves.
(1)- no 90 degree angles , nor near to 90 degrees angles , in any of the felt and spaces between.
(2)- no cut felt lines if extended to the driver domes are to form a Radius of the dome.
(3)- no cut felt lines are to form Tangents to circles that would be concentric with either of the domes.
It is essential to observe the above conditions if you want to improve on the performance of the asymetrically placed square cut felt pieces in David Ralph's photos.
Cut small Triangle shape pieces of felt if you want to cover the clamps that hold the drivers to the baffle.
Point an Apex of each triangle towards the centre of each dome.
You will need very sharp sizzors , or sharp serrated sizzors , to cut thick felt neatly.
Also , I recommend you first cut templates of the shapes you intend to use from thick paper or thin cardboard
and use those over the felt when cutting it to shape.
DennyG ,
you will get more useful measurement results if you cover the baffles as above.
Continuing from my Post #929 on Page 93:
SAE specification felts are known as Engineering Felts.
Industrial felts are known as Technical Felts.
Both types are available in various thicknesses ,
and in various Sheet or Roll sizes , and not all suppliers will have all options of sizes , so you will have to search the internet or a printed Trade Directory for your area.
I drew some options to scale for the 66 baffle with regard to the drivers' sizes and spacings.
I do not have access to a scanner to post my drawings here , so I will attempt a diagram using several keyboard key symbols , as follows:
# for the extended wood of the Top of Cabinet Lip ,
0 shows the inner edge of the vertical recessed strip -{ only Left side will be shown } ,
* for Felt covered area , including where the felt overlaps the chassis of the driver's mounting ,
X to form the circles that are the edge of the drivers' chassis ,
and for the clamps that hold the drivers to the baffle.
x for the flat sections of the drivers' chassis and the surfaces of the domes ,
O for the circumferences of the domes.
Note: there is no clamp shown at the top of the tweeter chassis because the felt is to cover over that clamp.
o is for uncovered areas of the baffle , because the blanks spacer bar does not save to completion of posting.
Edge details for the Right side are not shown , because the small typing box is not wide enough for me to calculate easily how to include the Right side ,
however the Right side is to be the mirror image of the shown Left side.
I do not know what caused the wavey line down through the Right area of the diagram ... ?
_________________________________________________________________
####################################################
####################################################
0*********************************************************
0*********************************************************
0**oooo***************************************************
0***oooooooooooo*******************************************
0****ooooooooooooooooooooooo************************
0*****oooooooooooooooooooooooooooooooX*****X
0******oooooooooooooooooooooooooooXxxxxxx*xxxxxX
0*******ooooooooooooooooooooooooXxxxxxOxxxxxOxxxxX
0********ooooooooooooooooooooooXxxxxxOxxxxxxxOxxxxX
0*******ooooooooooooooooooooooooXxxxxxOxxxxxOxxxxX
0******oooooooooooooooooooooooooooXxxxxxO_OxxxxxX
0*****oooooooooooooooooooooooooooXoooXxxxxxxxXoooX
0****ooooooooooooooooooooooooooooooooooooX
0***oooooooooooooooooooooooooooooooooooooo
0***oooooooooooooooooooooooooooooooooooooo
0****oooooooooooooooooooooooooooooooooooXXX
0*****ooooooooooooooooooooXooooooooXxxxxxxxxxxxxxXoooooooX
0******oooooooooooooooooooooXooXxxxxxxxxxxxxxxxxxxxxxXooX
0*******oooooooooooooooooooXxxXxxxxxxxxxxxxxxxxxxxxxxxxX
0********ooooooooooooooooXxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxX
0*******ooooooooooooooooXxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxX
0******ooooooooooooooooXxxxxxxxxxxxxxxxxxxxOOxxxxxxxxxxxxxxxxxX
0*****ooooooooooooooooXxxxxxxxxxxxxxxOxxxxxxxxxxxOxxxxxxxxxxxxxX
0****ooooooooooooooooXxxxxxxxxxxxxxOxxxxxxxxxxxxxxxxOxxxxxxxxxxxX
0***oooooooooooooooooXxxxxxxxxxxxxOxxxxxxxxxxxxxxxxxxOxxxxxxxxxxxX
0***oooooooooooooooooXxxxxxxxxxxxxOxxxxxxxxxxxxxxxxxxOxxxxxxxxxxxX
0****ooooooooooooooooXxxxxxxxxxxxxxOxxxxxxxxxxxxxxxxOxxxxxxxxxxxX
0*****ooooooooooooooooXxxxxxxxxxxxxxxOxxxxxxxxxxxxOxxxxxxxxxxxxX
0******ooooooooooooooooXxxxxxxxxxxxxxxxxxxxOOxxxxxxxxxxxxxxxxX
0*******oooooooooooooooooXxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxX
0********ooooooooooooooooooXxxxxxxxxxxxxxxxxxxxxxxxxxxxxxX
0*******ooooooooooooooooooXoooXxxxxxxxxxxxx*xxxxxxxxxxXoooX
0******ooooooooooooooooooXooooooooooooo*****oooooooooooooX
0*****ooooooooooooooooooooooooooooo*************
0****oooooooooooooooooooooooo***********************
0***ooooooooooooooooooooo********************************
0****ooooooooooooooo***************************************
0*****oooooooo*********************************************
0******o**************************************************
0*************************************O*******************
0**********************OxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxO*****
0*****************OxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxO
0**************O
0***********O
0*********O
0*******O
0*****O
0****O
0***O
0**O
0*O
0O
0<------------------------------this part circular space is the woofer--->
0O
_________________________________________________________________
The diagram is not exactly to Scale , because it was too difficult to get such to work with the between lines spacings , etc ...
No felt is needed below the woofer , as it would not be effective there.
For most of the area to be covered quarter inch thick felt is sufficient if it is very soft and porous ,
though half inch thick will produce somewhat better results.
For the area above the tweeter to the top wooden lip use 1 inch thick felt ,
or cut 2 pieces from half inch and stack them , because ALL the underside of that wood must be covered ,
or there will be destructive reflections.
To stick these two pieces together apply Fabric Adhesive to the back half only of the surfaces ,
because if there is adhesive solid at the front edge the sound waves will not absorb as well as possible.
The felt here must be placed so that it has open cut edges facing downwards for there to be absorption of sound from the tweeter.
In #929 I stated to cut Acute angles for the zig-zag side of baffle felt.
That will not work well with this narrow baffle , so cut Obtuse angles , as shown.
The felt above the tweeter , and between the mid-dome and woofer , can be cut to an obtuse angle apex , or slightly curved around the apex.
Do whichever you prefer the look of.
For all the felt cuts observe the following three conditions , or there will be some destructive reflections because the felt is not completely absorptive of sound waves.
(1)- no 90 degree angles , nor near to 90 degrees angles , in any of the felt and spaces between.
(2)- no cut felt lines if extended to the driver domes are to form a Radius of the dome.
(3)- no cut felt lines are to form Tangents to circles that would be concentric with either of the domes.
It is essential to observe the above conditions if you want to improve on the performance of the asymetrically placed square cut felt pieces in David Ralph's photos.
Cut small Triangle shape pieces of felt if you want to cover the clamps that hold the drivers to the baffle.
Point an Apex of each triangle towards the centre of each dome.
You will need very sharp sizzors , or sharp serrated sizzors , to cut thick felt neatly.
Also , I recommend you first cut templates of the shapes you intend to use from thick paper or thin cardboard
and use those over the felt when cutting it to shape.
DennyG ,
you will get more useful measurement results if you cover the baffles as above.
Last edited:
Hi everyone. As a newbie, firstly a big thanks to Alan, who's advice I've followed in restoring my recently purchased 66s. The crossovers have been recapped with Jantzen caps and compensating resistors as advised, internal wiring replaced, and the sound has been transformed. They used to be a bit woolly and lacking in detail, but now have a clear finely detailed sound with much tighter bass. Not a subtle improvement by any means.
They sound very impressive, and regularly raise a smile, but I find the balance just a touch forward in the mid. I do recall them being this way inclined before the recap. I can't tell if it's the overall mid driver level that needs to come down, or if there's a crossover resonance creating a bit of a glare. I've experimented with varying the value of the esr resistors (within the accepted margins) which seems to have tempered it slightly.
So, what to do next? I'm tempted to upgrade the LF inductors to thicker gauge, to increase the level of the overall band up to 500Hz and further tighten the bass, and maybe balance better with the mid and top, but I'm wary of making them bass-heavy. Or maybe try an L-pad on the mid driver? Any thoughts would be appreciated.
Andrzej
They sound very impressive, and regularly raise a smile, but I find the balance just a touch forward in the mid. I do recall them being this way inclined before the recap. I can't tell if it's the overall mid driver level that needs to come down, or if there's a crossover resonance creating a bit of a glare. I've experimented with varying the value of the esr resistors (within the accepted margins) which seems to have tempered it slightly.
So, what to do next? I'm tempted to upgrade the LF inductors to thicker gauge, to increase the level of the overall band up to 500Hz and further tighten the bass, and maybe balance better with the mid and top, but I'm wary of making them bass-heavy. Or maybe try an L-pad on the mid driver? Any thoughts would be appreciated.
Andrzej
interim ...
Where are you apb ?
Attach a National flag to your user name ,
and that is useful if I advise on where to buy parts from.
Thankyou for your report about the changes to the sound ,
as that is useful to all owners of 66s here !
You stated:
"but I find the balance just a touch forward in the mid"
Is that over the entire midrange ?
or only the low mids , or the high mids , or in a narrow band somewhere in the midrange ?
I mentioned the narrow band option because you stated:
"if there's a crossover resonance creating a bit of a glare."
All Band-Pass filters , except for simple First Order of one inductor + one capacitor , are resonant to some degree.
The degree depends on the Order of the filter -{ 2nd , 3rd , 4th }- and how much Resistance is in the circuit.
In the 66 , the resistance of the 2.2mH inductor reduces the resonance a little ,
and the compensating resistor I advised to connect in Series with the 3.9 or 4uF capacitor reduces it a little more.
Some of the Celestion mid-domes become more resonant in themselves as they age -
- see the various plots of Impedance and Frequency Response that sba has posted in places in this thread.
If either of your domes has become excessively resonant there is nothing you can do easily about it , but only more complicated repairs.
I recommend you listen carefully to each speaker by itself -{ not the pair together }-
to hear if one or other of the mid-domes sounds more resonant than the other , and if one does , then post about that here ,
as well as stating more about the midrange as I asked above.
List the resistance values you installed , in mid and woofer circuits.
Depending on your reply about the type of midrange excess , I may advise swapping around some of those resistors.
If the entire midrange is slightly too loud only , then replacing the two inductors in the woofer filter only with significantly lower DC resistance types will allow a little more bass output to balance the mids ,
plus will tighten up the bass a bit , BUT the choice of inductor has to be done carefully or the result may not be better but only different ...
I will be posting more about that for other interested participants here soon.
What I will be advising will not cause the l'speakers to be "bass heavy".
*** *** ***
I will return with a bit more about placing Felt on the front baffle when I have time available ,
hopefully soon ...
Where are you apb ?
Attach a National flag to your user name ,
and that is useful if I advise on where to buy parts from.
Thankyou for your report about the changes to the sound ,
as that is useful to all owners of 66s here !
You stated:
"but I find the balance just a touch forward in the mid"
Is that over the entire midrange ?
or only the low mids , or the high mids , or in a narrow band somewhere in the midrange ?
I mentioned the narrow band option because you stated:
"if there's a crossover resonance creating a bit of a glare."
All Band-Pass filters , except for simple First Order of one inductor + one capacitor , are resonant to some degree.
The degree depends on the Order of the filter -{ 2nd , 3rd , 4th }- and how much Resistance is in the circuit.
In the 66 , the resistance of the 2.2mH inductor reduces the resonance a little ,
and the compensating resistor I advised to connect in Series with the 3.9 or 4uF capacitor reduces it a little more.
Some of the Celestion mid-domes become more resonant in themselves as they age -
- see the various plots of Impedance and Frequency Response that sba has posted in places in this thread.
If either of your domes has become excessively resonant there is nothing you can do easily about it , but only more complicated repairs.
I recommend you listen carefully to each speaker by itself -{ not the pair together }-
to hear if one or other of the mid-domes sounds more resonant than the other , and if one does , then post about that here ,
as well as stating more about the midrange as I asked above.
List the resistance values you installed , in mid and woofer circuits.
Depending on your reply about the type of midrange excess , I may advise swapping around some of those resistors.
If the entire midrange is slightly too loud only , then replacing the two inductors in the woofer filter only with significantly lower DC resistance types will allow a little more bass output to balance the mids ,
plus will tighten up the bass a bit , BUT the choice of inductor has to be done carefully or the result may not be better but only different ...
I will be posting more about that for other interested participants here soon.
What I will be advising will not cause the l'speakers to be "bass heavy".
*** *** ***
I will return with a bit more about placing Felt on the front baffle when I have time available ,
hopefully soon ...
Thanks for the reply. I've now edited my location.
I can't tell just yet if it's one particular frequency or the whole band, but will experiment with a parametric EQ in order to try to locate the offending frequencies and report back.
I will post up a circuit diagram with all component values I used when I get a chance to have a look.
I will also post links to some LF inductors I found and am considering.
Regards
Andrzej
I can't tell just yet if it's one particular frequency or the whole band, but will experiment with a parametric EQ in order to try to locate the offending frequencies and report back.
I will post up a circuit diagram with all component values I used when I get a chance to have a look.
I will also post links to some LF inductors I found and am considering.
Regards
Andrzej
Continuing from #931 above , and more about felts ...
I stated in #931:
(3)- above needs clarification , I should have included at the end of the sentance:
... if the cut felt extends as a Tangent past a Radius of the dome.
because obviously for several of the felt cuts above if a line was extended from , it would be a Tangent to a concentric circle.
There is no major acoustic problem caused by what I drew in #931 ,
however it can be improved further , as below:
H is now the symbol for the Clamps' positions around the tweeter and mid-dome in the below diagram ,
and as in the previous diagram the top clamp above the tweeter is covered by felt.
All other symbols are the same as in the previous diagram ,
and the centre of both domes are now marked with O .
__________________________________________________ _______________
################################################## ##
################################################## ##
0************************************************* ********
0************************************************* ********
0*****oo****************************************** *******
0******ooooooooo********************************** ********
0*******oooooooooooooooooooo********************** **
0********ooooooooooooooooooooooooooooX*****X
0*********ooooooooooooooooooooooooXxxxxxx*xxxxxxX
0**********oooooooooooooooooooooXxxxxxOxxxxxOxxxx X
0***********oooooooooooooooooooXxxxxxOxxxOxxxOxxxx X
0**********oooooooooooooooooooooXxxHxxOxxxxxOxxHx X
0*********oooooooooooooooooooooooHxxxxxxO_OxxxxxxH
0********ooooooooooooooooooooooHoooXxxxxxxxxxxxXooH
0*******oooooooooooooooooooooooooooooooooX
0******ooooooooooooooooooooooooooooooooooo
0*****oooooooooooooooooooooooooooooooooooo
0****oooooooooooooooooooooooooooooooooooXXX
0***ooooooooooooooooooooooHoooooooXxxxxxxxxxxxxxxx XooooooH
0****oooooooooooooooooooooooHXxxxxxxxxxxxxxxxxxxxx xxxxxXH
0*****ooooooooooooooooooooXxxxHxxxxxxxxxxxxxxxxxxx xxxxHxxxX
0******oooooooooooooooooXxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxX
0*******oooooooooooooooXxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxX
0********oooooooooooooXxxxxxxxxxxxxxxxxxxxxOOxxxxx xxxxxxxxxxxxxX
0*********oooooooooooXxxxxxxxxxxxxxxxOxxxxxxxxxxxO xxxxxxxxxxxxxxX
0**********oooooooooXxxxxxxxxxxxxxxOxxxxxxxxxxxxxx xOxxxxxxxxxxxxxX
0***********oooooooXxxxxxxxxxxxxxOxxxxxxxxxxxxxxx xxxOxxxxxxxxxxxxxX
0************ooooooXxxxxxxxxxxxxxIxxxxxxxxxxOxxxxxxxxIxxxxxxxxxxxxxX
0***********oooooooXxxxxxxxxxxxxxOxxxxxxxxxxxxxxx xxxOxxxxxxxxxxxxxX
0**********oooooooooXxxxxxxxxxxxxxOxxxxxxxxxxxxxx xxOxxxxxxxxxxxxxX
0*********oooooooooooXxxxxxxxxxxxxxxOxxxxxxxxxxxx OxxxxxxxxxxxxxxX
0********oooooooooooooXxxxxxxxxxxxxxxxxxxxxOOxxxx xxxxxxxxxxxxxxX
0*******ooooooooooooooooXxxxxHxxxxxxxxxxxxxxxxxxxx xxxxxxHxxxxX
0******ooooooooooooooooooooHXxxxxxxxxxxxxxxxxxxxxx xxxxxxxXH
0*****ooooooooooooooooooooHoooooooXxxxxxxxxxxxxxx xxXooooooH
0****ooooooooooooooooooooooooooooooooooooXXXooooooooo ooooooo
0***ooooooooooooooooooooooooooooooooooooo***ooooooooo ooooooo
0****oooooooooooooooooooooooooooooooo********** oooooooooooo
0*****ooooooooooooooooooooooooooo***************** oooooooo
0******oooooooooooooooooooooo********************* **ooooo
0*******ooooooooooooooooo************************* *****oo
0********oooooooooooo***************************** ********
0*********ooooooo**********************O*********** *******
0**********oo***********Oxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxO*****
0*****************Oxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxx
0**************O
0***********O
0*********O
0*******O
0*****O
0****O
0***O
0**O
0*O
0O
0<------------------------------this part circular space is the woofer--->
0
__________________________________________________ _______________
The diagram is not exactly to Scale , because it was too difficult to get such to work with the between lines spacings , etc ...
Note for this version there is an Apex of felt pointing towards the centre of the mid-dome , { same as for the tweeter } ,
and that will cause better mids absorption , along with whatever residual reflection being diverted to further absorptive cut edges of felt.
***
Alternate:
If you cannot get thick soft SAE spec Engineering felt , or thick soft Technical/Industrial felt ,
then for the thinner Craft felts buy a type that is equal thickness to the flange of the mid-dome ,
and cut precise circular holes in it for tweeter and mid-dome , and cover the entire front baffle from above the woofer , and to the inner edges of the vertical recesses.
Roll some up loosely and stick it under the overhanging lip at the top of the cabinet to cover the entire under surface of that lip.
***
Felt Colour:
Pure Wool and 95% Wool felts are White colour.
If you try to dye it a colour the later dryed dye will cause stiffness within the felt , thus less sound absorption , so do not dye white felt.
If you do not want white colour , then in the SAE specification felts F-11 is pale grey , and F-13 is slightly darker grey.
See the photos of the F-11 and F-13 grey felts on David Ralph's web-site.
At least one photo has both greys - the colour difference is small , but is noticeable.
These are not quite as absorptive as F-10 , but are not bad , and are better than home-dyed felt for sound absorption.
In Technical/Industrial felts there are some pale grey versions ,
which same as for Engineering/SAE , the grey ones are less than 95% Wool ,
but there are some in the very soft , low density specification.
Craft felts are manufactured from various colour dyed strands of Wool , and Rayon , etc ... { and from synthetic fibres }.
Because the fibre is pre-dyed , the felt made from it is softer than if dyed after the felt was formed ,
so if you want coloured felt buy Craft Felt , but find a Pure Wool type if you can ,
or at least a high wool/low rayon composite , and not a fully synthetic fibre felt , such as Acrylic , etc ...
***
I think I have posted sufficient about Felt , but do ask if something is not sufficiently explained.
Next time here I will return to finishing another of the topics we have been discussing - maybe for "reggie" , if he is reading ...
unless something else is asked.
I stated in #931:
(3)- above needs clarification , I should have included at the end of the sentance:
... if the cut felt extends as a Tangent past a Radius of the dome.
because obviously for several of the felt cuts above if a line was extended from , it would be a Tangent to a concentric circle.
There is no major acoustic problem caused by what I drew in #931 ,
however it can be improved further , as below:
H is now the symbol for the Clamps' positions around the tweeter and mid-dome in the below diagram ,
and as in the previous diagram the top clamp above the tweeter is covered by felt.
All other symbols are the same as in the previous diagram ,
and the centre of both domes are now marked with O .
__________________________________________________ _______________
################################################## ##
################################################## ##
0************************************************* ********
0************************************************* ********
0*****oo****************************************** *******
0******ooooooooo********************************** ********
0*******oooooooooooooooooooo********************** **
0********ooooooooooooooooooooooooooooX*****X
0*********ooooooooooooooooooooooooXxxxxxx*xxxxxxX
0**********oooooooooooooooooooooXxxxxxOxxxxxOxxxx X
0***********oooooooooooooooooooXxxxxxOxxxOxxxOxxxx X
0**********oooooooooooooooooooooXxxHxxOxxxxxOxxHx X
0*********oooooooooooooooooooooooHxxxxxxO_OxxxxxxH
0********ooooooooooooooooooooooHoooXxxxxxxxxxxxXooH
0*******oooooooooooooooooooooooooooooooooX
0******ooooooooooooooooooooooooooooooooooo
0*****oooooooooooooooooooooooooooooooooooo
0****oooooooooooooooooooooooooooooooooooXXX
0***ooooooooooooooooooooooHoooooooXxxxxxxxxxxxxxxx XooooooH
0****oooooooooooooooooooooooHXxxxxxxxxxxxxxxxxxxxx xxxxxXH
0*****ooooooooooooooooooooXxxxHxxxxxxxxxxxxxxxxxxx xxxxHxxxX
0******oooooooooooooooooXxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxX
0*******oooooooooooooooXxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxX
0********oooooooooooooXxxxxxxxxxxxxxxxxxxxxOOxxxxx xxxxxxxxxxxxxX
0*********oooooooooooXxxxxxxxxxxxxxxxOxxxxxxxxxxxO xxxxxxxxxxxxxxX
0**********oooooooooXxxxxxxxxxxxxxxOxxxxxxxxxxxxxx xOxxxxxxxxxxxxxX
0***********oooooooXxxxxxxxxxxxxxOxxxxxxxxxxxxxxx xxxOxxxxxxxxxxxxxX
0************ooooooXxxxxxxxxxxxxxIxxxxxxxxxxOxxxxxxxxIxxxxxxxxxxxxxX
0***********oooooooXxxxxxxxxxxxxxOxxxxxxxxxxxxxxx xxxOxxxxxxxxxxxxxX
0**********oooooooooXxxxxxxxxxxxxxOxxxxxxxxxxxxxx xxOxxxxxxxxxxxxxX
0*********oooooooooooXxxxxxxxxxxxxxxOxxxxxxxxxxxx OxxxxxxxxxxxxxxX
0********oooooooooooooXxxxxxxxxxxxxxxxxxxxxOOxxxx xxxxxxxxxxxxxxX
0*******ooooooooooooooooXxxxxHxxxxxxxxxxxxxxxxxxxx xxxxxxHxxxxX
0******ooooooooooooooooooooHXxxxxxxxxxxxxxxxxxxxxx xxxxxxxXH
0*****ooooooooooooooooooooHoooooooXxxxxxxxxxxxxxx xxXooooooH
0****ooooooooooooooooooooooooooooooooooooXXXooooooooo ooooooo
0***ooooooooooooooooooooooooooooooooooooo***ooooooooo ooooooo
0****oooooooooooooooooooooooooooooooo********** oooooooooooo
0*****ooooooooooooooooooooooooooo***************** oooooooo
0******oooooooooooooooooooooo********************* **ooooo
0*******ooooooooooooooooo************************* *****oo
0********oooooooooooo***************************** ********
0*********ooooooo**********************O*********** *******
0**********oo***********Oxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxO*****
0*****************Oxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxx
0**************O
0***********O
0*********O
0*******O
0*****O
0****O
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0<------------------------------this part circular space is the woofer--->
0
__________________________________________________ _______________
The diagram is not exactly to Scale , because it was too difficult to get such to work with the between lines spacings , etc ...
Note for this version there is an Apex of felt pointing towards the centre of the mid-dome , { same as for the tweeter } ,
and that will cause better mids absorption , along with whatever residual reflection being diverted to further absorptive cut edges of felt.
***
Alternate:
If you cannot get thick soft SAE spec Engineering felt , or thick soft Technical/Industrial felt ,
then for the thinner Craft felts buy a type that is equal thickness to the flange of the mid-dome ,
and cut precise circular holes in it for tweeter and mid-dome , and cover the entire front baffle from above the woofer , and to the inner edges of the vertical recesses.
Roll some up loosely and stick it under the overhanging lip at the top of the cabinet to cover the entire under surface of that lip.
***
Felt Colour:
Pure Wool and 95% Wool felts are White colour.
If you try to dye it a colour the later dryed dye will cause stiffness within the felt , thus less sound absorption , so do not dye white felt.
If you do not want white colour , then in the SAE specification felts F-11 is pale grey , and F-13 is slightly darker grey.
See the photos of the F-11 and F-13 grey felts on David Ralph's web-site.
At least one photo has both greys - the colour difference is small , but is noticeable.
These are not quite as absorptive as F-10 , but are not bad , and are better than home-dyed felt for sound absorption.
In Technical/Industrial felts there are some pale grey versions ,
which same as for Engineering/SAE , the grey ones are less than 95% Wool ,
but there are some in the very soft , low density specification.
Craft felts are manufactured from various colour dyed strands of Wool , and Rayon , etc ... { and from synthetic fibres }.
Because the fibre is pre-dyed , the felt made from it is softer than if dyed after the felt was formed ,
so if you want coloured felt buy Craft Felt , but find a Pure Wool type if you can ,
or at least a high wool/low rayon composite , and not a fully synthetic fibre felt , such as Acrylic , etc ...
***
I think I have posted sufficient about Felt , but do ask if something is not sufficiently explained.
Next time here I will return to finishing another of the topics we have been discussing - maybe for "reggie" , if he is reading ...
unless something else is asked.
Last edited:
Hiquphon OWII tweeter , and continuing some other back-log
G'day Reggie ,
Looking at data for Hiquphon OWII tweeter here:
Hiquphon OWII (OW2) dome tweeter, technical data
and comparing it to the SEAS 19TFF1 and Hiquphon OWI ,
note that it is about 1dB more efficient in its lower treble , and 3dB more in its upper treble.
See the step in its frequency response between 4kHz and 5kHz.
That is a good co-incidence for this Celestion 66 project , because the upper crossover point is nominally 5kHz ,
thus for owners who have lost a bit of upper treble hearing the OWII can supply extra treble ,
including too much as Reggie found !
The Impedance plot is close to flat in the region around the crossover point , thus close to a standard 3rd order filter will work ,
and will work better with a resistor connected in Parallel with the tweeter as that will flatten the Impedance a little more.
The resistance can be chosen so that it in parallel with the tweeter reduces the total impedance to a suitable value to enable standard E Series capacitors to be used ,
and hopefully an available inductor.
Reggie has an L-Pad of 15 ohms parallel + 1 ohm series around his OWII.
That attenuates by about -2dB , and seems to have resulted in a suitable treble level for Reggie ... -{ yes or no Reggie ? }.
It will still be slightly brighter than treble would be with the SEAS 19TFF1 or OWI , but some listeners may need this slight additional amount of treble.
Dealing with all the above , and incorporating adapting the OWII into the 66 crossover:
Unless there is something wrong with the original Celestion treble inductor it may as well be retained.
The only other reason to change it would be if one's amplifier had difficulty driving the lower impedance load in the treble than is in the midrange ,
however as the impedance is lower than the midrange in the bass , and similar in the bass to what it is in the treble ,
then most amplifiers that drive its bass well will drive its treble well ... but not all , so decide that before proceeding.
For the L-Pad ,
keep the 15 ohms in parallel , in at least 5 watt if a good quality resistor , or higher power rating if a dubious quality resistor.
Buy 1.2 ohms for the series resistor -{ power ratings same as above }.
This will attenuate by slightly more than 2dB , and will set the total impedance to match what is required for the 0.14mH Celestion inductor.
For the capacitors use 3.6uF for the input cap , and either 11uF or 12uF for the output cap.
11 or 12 - which will work better ?
I do not know , however I think for shaping the treble to be slightly higher in output in the upper treble to compensate for hearing loss ,
along with the specific L-Pad resistors above in conjunction with an OWII that 11uF is likely to be more suitable ,
however the final result will depend on the upper end of the frequency response of the mid-domes ,
which as we have seen from sba's plots varies quite a lot between samples in the upper mids.
Some of them have sufficient upper mids output to not need any help from the tweeter, but for others it would assist upper mids' level if the treble sloped off a bit more gently ,
and for such cases use at least 12uF.
To simplify the choice , I recommend starting with whichever cap value is available from the seller of the 3.6uF , and listen to the result.
Given what else Reggie wants I think it best he uses SoniCap Gen I series
for which there is 3.6uF and 11uF available.
For UK and European residents there is 3.6uF and 12uF available in Jantzen Cross Caps for lower price than Sonicap { from USA } ,
however these may not be quite as good in audio quality , though still better than Solen ,
and are physically larger size than Sonicaps.
For the midrange filter Reggie ,
you have a Mundorf 22uF for the input cap.
This will cause slightly less level at the lowest midrange frequencies than the Celestion spec. 24uF ,
however , with the specific samples of the mid-domes and woofers in your 66s ,
if you have a pleasing amount of mids around the lower crossover region then leave the 22uF there , and the Mundorf is quite a good quality capacitor.
You can leave the Solen 3.9uF as output cap of the midrange filter , or upgrade it to a 3.9 or 4uF Sonicap
-{ both are available , and I'd choose the 4uF if it will fit the board - note it is shorter but fatter than the 3.9uF }.
If you want a little more of the lowest mids , then buy a 24uF Sonicap.
You can fine-tune the upper midrange/lower treble output by changing the resistor that is in series with the 4uF midrange output cap.
2.7 ohms , 3.3 ohms , 3.9 ohms , I recommend you leave in whichever you have there for now till you hear the result with correct L-pad and new caps to the tweeter.
If you want to buy a Mills MRA-5 for mids at same time as you are buying for treble , { as these Mills are available from Sonicap's web-site via Mail-order } ,
then buy 3.9 ohms/5 watt , as I think you have 2.7 ohms currently if I am remembering correctly ... ?
Sonicaps and Mills MRA-5 are available Mail-order from:
Sonic Craft High-End DIY Audio Parts
Other resistors:
Either 1.8 ohm or 1.5 ohm , 5 watt , in series with the 22uF/24uF mids' input cap.
Buy both values and start with 1.8 ohms in midrange and put the 1.5 ohms in series with the output cap of the woofer filter.
If you want a little more midrange level then swap those two resistors positions.
{ If I remember correctly you already have 1.5 ohms , but 1.8 ... ? }
For the between the inductors cap of the woofer filter use 1 ohm in series -{ which I think you already have ... ? }
Buy two 8 ohm , or 8.2 ohm , also these can be Mills 5 watt , but there will be very little current through these , thus lower power is OK ,
so if you want to buy cheaper resistors for these then buy in 1 watt Carbon film from a local shop.
In the woofer filter you currently have 68uF Solen caps in both positions.
Option 1 - leave 68uF + 1.5 ohms as the output capacitor and resistor.
Connect 1 ohms in Series with the other 68uF cap.
Connect the 8.2 ohms resistor in Series with your Solen 8.2uF cap that you are taking out of the tweeter filter.
Connect the 8.2 + 8.2 series in Parallel with the 68 + 1 series.
Do NOT connect the pairs together at their central junction capacitor to resistor joints.
Connect only at the end points of each series pair.
This option should give sufficient filtering , and it may be the optimum alternate if you are deciding to keep the 22uF in the midrange filter.
Option 2 - If you are not happy with the lower midrange sound after listening to the above ,
then remove the 8.2uF cap and install the Solen 3.9uF cap that you are taking out of your tweeter filter.
Leave the 8.2 ohm resistor there.
Now you will need another pair of 3.9uF caps , which you will have if you upgrade the output caps of the midrange filter to Sonicaps.
Buy two 15 ohm , 1 watt carbon film resistors from a local shop and connect these , one each in Series with the two additional Solen 3.9 uF caps.
Connect each of these series pairs in Parallel with the 68uF + 1.5 ohm series pair at the output of the woofer filter.
{ Connect as described in Option 1 , not short-circuiting the centre joins of each series pair to the other .}
You will then have effectively 72uF in each capacitor position , as is the Celestion specification ,
however try Option 1 first , because I think it may work a little better.
There were not as many capacitance values economically available when Celestion designed the 66 , thus they used the closest that was available , 72uF for both positions.
Obviously that worked well enough , but I think 76uF and 68uf could work a little better in the positions I described above.
---> DennyG - you have effectively 74uF in the central cap's position.
Ideally the 6.2uF cap you connected there needs its own separate resistor.
Use 8.2 ohm or 10 ohm in 1 watt Carbon film from a local shop.
If you have some 1 watt resistors already , then so long as not less than 4.7 ohms or larger than 12 ohms , try those you have.
Reggie ,
further about your worries of useable life of the old drivers in the 66s.
For a modern loudspeaker which will give similar scale of sound to a 66 , and will last longer than you ,
look on your local ebay , and in B&W stockists for Trade-ins of:
B&W 800S - that is the S version of the model 800.
These may be available now at affordable prices since B&W replaced them with the new 800D series.
D is Diamond tweeter version , and very expensive.
S have a good quality metal dome tweeter.
There was an interim Signature 800 , which was an 800S with deluxe finish , but owners may want a lot of money for those.
800 has a pair of 10" woofers , and have faster sound than 801 with its 12" woofer.
Both have a good quality mid-cone.
802 has a pair of 8" woofers , plus mid-cone and tweeter , but these do not have the weight of sound of the 800.
I do not recommend 803 and 804 for Celestion 66 lovers.
{ 805 is good for a stand mounted 2-way.}
Before the S series there was the Nautilus series , but these do not sound as good as the S series ,
however are not bad , but listen first because they do sound quite different to the S series.
I recommend you listen to one of the versions of the 800 at a B&W dealer , and with a high-end , high power amplifier ,
or take in your own amplifier and ask for demo in a small room to suit your amplifier's power.
Their vent/port can be blocked if the bass output is excessive , and with the 800 the bass goes low enough in frequency to not need the port output.
I think they sound better with the ports blocked.
Stuff the ports tightly with closed cell plastic foam or with any tightly rolled soft fabric - wool would be best.
***
I will return to post about upgrades to the Inductors in the woofer filter for higher and faster bass output when I have time available.
These will be from different sellers than the Sonicaps and Mills resistors ,
so you can buy those and start now , but do post here if you have interim queries.
G'day Reggie ,
Looking at data for Hiquphon OWII tweeter here:
Hiquphon OWII (OW2) dome tweeter, technical data
and comparing it to the SEAS 19TFF1 and Hiquphon OWI ,
note that it is about 1dB more efficient in its lower treble , and 3dB more in its upper treble.
See the step in its frequency response between 4kHz and 5kHz.
That is a good co-incidence for this Celestion 66 project , because the upper crossover point is nominally 5kHz ,
thus for owners who have lost a bit of upper treble hearing the OWII can supply extra treble ,
including too much as Reggie found !
The Impedance plot is close to flat in the region around the crossover point , thus close to a standard 3rd order filter will work ,
and will work better with a resistor connected in Parallel with the tweeter as that will flatten the Impedance a little more.
The resistance can be chosen so that it in parallel with the tweeter reduces the total impedance to a suitable value to enable standard E Series capacitors to be used ,
and hopefully an available inductor.
Reggie has an L-Pad of 15 ohms parallel + 1 ohm series around his OWII.
That attenuates by about -2dB , and seems to have resulted in a suitable treble level for Reggie ... -{ yes or no Reggie ? }.
It will still be slightly brighter than treble would be with the SEAS 19TFF1 or OWI , but some listeners may need this slight additional amount of treble.
Dealing with all the above , and incorporating adapting the OWII into the 66 crossover:
Unless there is something wrong with the original Celestion treble inductor it may as well be retained.
The only other reason to change it would be if one's amplifier had difficulty driving the lower impedance load in the treble than is in the midrange ,
however as the impedance is lower than the midrange in the bass , and similar in the bass to what it is in the treble ,
then most amplifiers that drive its bass well will drive its treble well ... but not all , so decide that before proceeding.
For the L-Pad ,
keep the 15 ohms in parallel , in at least 5 watt if a good quality resistor , or higher power rating if a dubious quality resistor.
Buy 1.2 ohms for the series resistor -{ power ratings same as above }.
This will attenuate by slightly more than 2dB , and will set the total impedance to match what is required for the 0.14mH Celestion inductor.
For the capacitors use 3.6uF for the input cap , and either 11uF or 12uF for the output cap.
11 or 12 - which will work better ?
I do not know , however I think for shaping the treble to be slightly higher in output in the upper treble to compensate for hearing loss ,
along with the specific L-Pad resistors above in conjunction with an OWII that 11uF is likely to be more suitable ,
however the final result will depend on the upper end of the frequency response of the mid-domes ,
which as we have seen from sba's plots varies quite a lot between samples in the upper mids.
Some of them have sufficient upper mids output to not need any help from the tweeter, but for others it would assist upper mids' level if the treble sloped off a bit more gently ,
and for such cases use at least 12uF.
To simplify the choice , I recommend starting with whichever cap value is available from the seller of the 3.6uF , and listen to the result.
Given what else Reggie wants I think it best he uses SoniCap Gen I series
for which there is 3.6uF and 11uF available.
For UK and European residents there is 3.6uF and 12uF available in Jantzen Cross Caps for lower price than Sonicap { from USA } ,
however these may not be quite as good in audio quality , though still better than Solen ,
and are physically larger size than Sonicaps.
For the midrange filter Reggie ,
you have a Mundorf 22uF for the input cap.
This will cause slightly less level at the lowest midrange frequencies than the Celestion spec. 24uF ,
however , with the specific samples of the mid-domes and woofers in your 66s ,
if you have a pleasing amount of mids around the lower crossover region then leave the 22uF there , and the Mundorf is quite a good quality capacitor.
You can leave the Solen 3.9uF as output cap of the midrange filter , or upgrade it to a 3.9 or 4uF Sonicap
-{ both are available , and I'd choose the 4uF if it will fit the board - note it is shorter but fatter than the 3.9uF }.
If you want a little more of the lowest mids , then buy a 24uF Sonicap.
You can fine-tune the upper midrange/lower treble output by changing the resistor that is in series with the 4uF midrange output cap.
2.7 ohms , 3.3 ohms , 3.9 ohms , I recommend you leave in whichever you have there for now till you hear the result with correct L-pad and new caps to the tweeter.
If you want to buy a Mills MRA-5 for mids at same time as you are buying for treble , { as these Mills are available from Sonicap's web-site via Mail-order } ,
then buy 3.9 ohms/5 watt , as I think you have 2.7 ohms currently if I am remembering correctly ... ?
Sonicaps and Mills MRA-5 are available Mail-order from:
Sonic Craft High-End DIY Audio Parts
Other resistors:
Either 1.8 ohm or 1.5 ohm , 5 watt , in series with the 22uF/24uF mids' input cap.
Buy both values and start with 1.8 ohms in midrange and put the 1.5 ohms in series with the output cap of the woofer filter.
If you want a little more midrange level then swap those two resistors positions.
{ If I remember correctly you already have 1.5 ohms , but 1.8 ... ? }
For the between the inductors cap of the woofer filter use 1 ohm in series -{ which I think you already have ... ? }
Buy two 8 ohm , or 8.2 ohm , also these can be Mills 5 watt , but there will be very little current through these , thus lower power is OK ,
so if you want to buy cheaper resistors for these then buy in 1 watt Carbon film from a local shop.
In the woofer filter you currently have 68uF Solen caps in both positions.
Option 1 - leave 68uF + 1.5 ohms as the output capacitor and resistor.
Connect 1 ohms in Series with the other 68uF cap.
Connect the 8.2 ohms resistor in Series with your Solen 8.2uF cap that you are taking out of the tweeter filter.
Connect the 8.2 + 8.2 series in Parallel with the 68 + 1 series.
Do NOT connect the pairs together at their central junction capacitor to resistor joints.
Connect only at the end points of each series pair.
This option should give sufficient filtering , and it may be the optimum alternate if you are deciding to keep the 22uF in the midrange filter.
Option 2 - If you are not happy with the lower midrange sound after listening to the above ,
then remove the 8.2uF cap and install the Solen 3.9uF cap that you are taking out of your tweeter filter.
Leave the 8.2 ohm resistor there.
Now you will need another pair of 3.9uF caps , which you will have if you upgrade the output caps of the midrange filter to Sonicaps.
Buy two 15 ohm , 1 watt carbon film resistors from a local shop and connect these , one each in Series with the two additional Solen 3.9 uF caps.
Connect each of these series pairs in Parallel with the 68uF + 1.5 ohm series pair at the output of the woofer filter.
{ Connect as described in Option 1 , not short-circuiting the centre joins of each series pair to the other .}
You will then have effectively 72uF in each capacitor position , as is the Celestion specification ,
however try Option 1 first , because I think it may work a little better.
There were not as many capacitance values economically available when Celestion designed the 66 , thus they used the closest that was available , 72uF for both positions.
Obviously that worked well enough , but I think 76uF and 68uf could work a little better in the positions I described above.
---> DennyG - you have effectively 74uF in the central cap's position.
Ideally the 6.2uF cap you connected there needs its own separate resistor.
Use 8.2 ohm or 10 ohm in 1 watt Carbon film from a local shop.
If you have some 1 watt resistors already , then so long as not less than 4.7 ohms or larger than 12 ohms , try those you have.
Reggie ,
further about your worries of useable life of the old drivers in the 66s.
For a modern loudspeaker which will give similar scale of sound to a 66 , and will last longer than you ,
look on your local ebay , and in B&W stockists for Trade-ins of:
B&W 800S - that is the S version of the model 800.
These may be available now at affordable prices since B&W replaced them with the new 800D series.
D is Diamond tweeter version , and very expensive.
S have a good quality metal dome tweeter.
There was an interim Signature 800 , which was an 800S with deluxe finish , but owners may want a lot of money for those.
800 has a pair of 10" woofers , and have faster sound than 801 with its 12" woofer.
Both have a good quality mid-cone.
802 has a pair of 8" woofers , plus mid-cone and tweeter , but these do not have the weight of sound of the 800.
I do not recommend 803 and 804 for Celestion 66 lovers.
{ 805 is good for a stand mounted 2-way.}
Before the S series there was the Nautilus series , but these do not sound as good as the S series ,
however are not bad , but listen first because they do sound quite different to the S series.
I recommend you listen to one of the versions of the 800 at a B&W dealer , and with a high-end , high power amplifier ,
or take in your own amplifier and ask for demo in a small room to suit your amplifier's power.
Their vent/port can be blocked if the bass output is excessive , and with the 800 the bass goes low enough in frequency to not need the port output.
I think they sound better with the ports blocked.
Stuff the ports tightly with closed cell plastic foam or with any tightly rolled soft fabric - wool would be best.
***
I will return to post about upgrades to the Inductors in the woofer filter for higher and faster bass output when I have time available.
These will be from different sellers than the Sonicaps and Mills resistors ,
so you can buy those and start now , but do post here if you have interim queries.
a correction , and some additions to my #937
Correction:
About B&W 801 , it was the older versions that had the 12" woofer.
Recent versions had a 15" woofer, though there seems to be no 801D for the new Diamond tweeter series ,
probably because it was found that most listeners to the S series preferred the 800S with its two 10" than the 801S with its 15".
Reggie ,
if shops in your city have only the 802 , it is still worth hearing , as it will give you some idea of the large sound , and it does have same mid-cone as 800.
*
I have looked again at the Soniccraft web-site.
The Sonicap GEN 1 caps that are on the Specials page at reduced price are their older +/- 10% tolerance versions.
I recommend you do not buy those because all will be distant in value to their nominal ,
because the close to nominal samples will have been sold to buyers who pay for sample measured capacitors.
Buy the new versions from the GEN 1 page , and in the 200 volt rating , as you do not need the larger 400 volt size for Celestion 66
- 66 will never accept such voltage , nor even 200 volts , even on peaks.
I see Sonic Craft sell some audio quality 1 watt resistors:
There is no 8.2 ohms , but if you want to buy a quality 1 watt for the 8.2uF cap addition to your woofer filter , the Takman 4R7 -{ 4.7 ohms }- will be OK there.
For the Option 2 , 15 ohms may be a little high , I now think 12 ohms may be better.
There is no 12 ohms in 1 watt from Sonic Craft , but the Takman 11R will suffice , and the PRP 11R may be a little better.
{ 11R is 11 ohms.}
*
Reggie ,
the combined effect of the Frequency response and the Impedance variation over the bandwidth of the Hiquphon OWII with the particular L-Pad resistors
and capacitor values + inductor you have currently is such that there will be a bit of a dip in output in the low end of the treble , and a slope up to a small peak in the upper treble.
You may not hear the upper treble peak , { but perhaps your wife can ...} ,
however the lower treble dip will cause the average of treble level to sound lower output than will be the case after you install the 11uF cap which will fill in the lower treble dip.
Thus do not worry that increasing the Series resistor to 1.2 ohms will reduce treble to lower than is now audible - it won't after the effect of 11uF cap.
If you are happy with the average level of treble now , then proceed as I advised in #937 ,
but if you think you may want more treble overall , then buy 1.1 ohms and 18 ohms in Mills MRA-5 , 5 watt , for the L-Pad.
If you think you may want less treble than you have now , post here before you buy and describe the degree of treble difference you want.
Correction:
About B&W 801 , it was the older versions that had the 12" woofer.
Recent versions had a 15" woofer, though there seems to be no 801D for the new Diamond tweeter series ,
probably because it was found that most listeners to the S series preferred the 800S with its two 10" than the 801S with its 15".
Reggie ,
if shops in your city have only the 802 , it is still worth hearing , as it will give you some idea of the large sound , and it does have same mid-cone as 800.
*
I have looked again at the Soniccraft web-site.
The Sonicap GEN 1 caps that are on the Specials page at reduced price are their older +/- 10% tolerance versions.
I recommend you do not buy those because all will be distant in value to their nominal ,
because the close to nominal samples will have been sold to buyers who pay for sample measured capacitors.
Buy the new versions from the GEN 1 page , and in the 200 volt rating , as you do not need the larger 400 volt size for Celestion 66
- 66 will never accept such voltage , nor even 200 volts , even on peaks.
I see Sonic Craft sell some audio quality 1 watt resistors:
There is no 8.2 ohms , but if you want to buy a quality 1 watt for the 8.2uF cap addition to your woofer filter , the Takman 4R7 -{ 4.7 ohms }- will be OK there.
For the Option 2 , 15 ohms may be a little high , I now think 12 ohms may be better.
There is no 12 ohms in 1 watt from Sonic Craft , but the Takman 11R will suffice , and the PRP 11R may be a little better.
{ 11R is 11 ohms.}
*
Reggie ,
the combined effect of the Frequency response and the Impedance variation over the bandwidth of the Hiquphon OWII with the particular L-Pad resistors
and capacitor values + inductor you have currently is such that there will be a bit of a dip in output in the low end of the treble , and a slope up to a small peak in the upper treble.
You may not hear the upper treble peak , { but perhaps your wife can ...} ,
however the lower treble dip will cause the average of treble level to sound lower output than will be the case after you install the 11uF cap which will fill in the lower treble dip.
Thus do not worry that increasing the Series resistor to 1.2 ohms will reduce treble to lower than is now audible - it won't after the effect of 11uF cap.
If you are happy with the average level of treble now , then proceed as I advised in #937 ,
but if you think you may want more treble overall , then buy 1.1 ohms and 18 ohms in Mills MRA-5 , 5 watt , for the L-Pad.
If you think you may want less treble than you have now , post here before you buy and describe the degree of treble difference you want.
Thank you Alan. I'm away for a week (at the beach) so I've printed this off and will sit and read it (while others are frolicking). I tried to post the Celestion review but the machine tells me it's too long for a post (679,000 bits while only 30,000 permitted - funny because it's only one page in length). I'll have to find a circumvention (?)
Reggie
Reggie
to Reggie ; DennyG ; and whoever is following these topics
G'day Reggie ,
there was reported to have been a cyclone , or similar , along the East coast of Australia ,
and there you are "at the beach" !
Well , I hope your prints did not get blown away ...
As for posting the Celestion review , given the almost 23:1 ratio of bits versus bits permitted ,
you would need to substantially reduce Resolution ... but that would likely be irrelevant to a direct Posting here.
I do not have expertise in these matters , however it seems that one posts the specific page onto a file saving web-page ,
and then posts a Link from here to that file saving page.
Example: have a look on Page 87 of this thread at #866.
See how much DennyG has managed to get stored on:
home.exetel.com.au
and linked to here.
As that seems to be an Australian web-site , you may be able to easily use it.
Perhaps some other readers here can advise Reggie on how to store a lot of data and link it to here ..?
G'day DennyG ,
hopefully those Celestion 66s work !
... or maybe their buyer will find us here ...
I don't know how there could be "zero latency" through a digital device ,
but perhaps the reference is to zero added latency when adding new data to stored data within the device ...
As you may be about to start measuring again , I refer you back to what I posted on Page 89 in #890 ,
and also to the baffle treatment I posted above , as that will give you results with minimal diffraction and reflection errors.
What I forgot to advise you last time , particually as you used your Sugden A28 to drive the speakers whilst measuring:
those old capacitors in the Sugden would have deteriorated in a non-linear manner ,
and differently between samples , thus one channel of the Sugden itself would have measured differently to the other - particually in the Treble.
Even with the new caps installed , as they are Electrolytics they will not be identical sample to sample for caps of the same value ,
thus , do all the measuring using ONE channel of the amplifier for all drivers ,
or at least for all drivers of the same type.
Eg: you may find your HF2000 tweeters are not as different to each other after you measure both using the same channel of the amplfier.
One needs to ensure one is measuring the differences between the drivers.
Later one can measure to find if any degree of difference between channels of the ampifier ...
and for that I recommend using a 10 watt 6.8 ohm wirewound resistor for the basic measurement for reference to Celestion 66 impedances.
Use same sample of the resistor to measure each channel of the amp.
Use sufficient power from the amp for the resistor to get slightly warm to touch - not hot , nor cold.
If you want to measure for higher power output level differences you will have to buy 20 or 25 watt or higher power resistors ,
or Parallel connect several 10 watters - which is what I do.
Amplifiers that measure close to identical channel to channel into Resistive loads sometimes do not into Reactive loads.
To test into a reactive load , connect the 6.8 ohm resistor to the output of one Celestion midrange filter , and 4.7 ohm/10 watts to outputs of its woofer and tweeter filters ,
and use that one test filter to measure each channel of the amplifier.
Here you will not get equal output across the full frequency bandwidth.
What one needs to do here is look at the relative output of each channel versus the other at the same frequency for all the measured frequencies.
G'day Reggie ,
there was reported to have been a cyclone , or similar , along the East coast of Australia ,
and there you are "at the beach" !
Well , I hope your prints did not get blown away ...
As for posting the Celestion review , given the almost 23:1 ratio of bits versus bits permitted ,
you would need to substantially reduce Resolution ... but that would likely be irrelevant to a direct Posting here.
I do not have expertise in these matters , however it seems that one posts the specific page onto a file saving web-page ,
and then posts a Link from here to that file saving page.
Example: have a look on Page 87 of this thread at #866.
See how much DennyG has managed to get stored on:
home.exetel.com.au
and linked to here.
As that seems to be an Australian web-site , you may be able to easily use it.
Perhaps some other readers here can advise Reggie on how to store a lot of data and link it to here ..?
G'day DennyG ,
hopefully those Celestion 66s work !
... or maybe their buyer will find us here ...
I don't know how there could be "zero latency" through a digital device ,
but perhaps the reference is to zero added latency when adding new data to stored data within the device ...
As you may be about to start measuring again , I refer you back to what I posted on Page 89 in #890 ,
and also to the baffle treatment I posted above , as that will give you results with minimal diffraction and reflection errors.
What I forgot to advise you last time , particually as you used your Sugden A28 to drive the speakers whilst measuring:
those old capacitors in the Sugden would have deteriorated in a non-linear manner ,
and differently between samples , thus one channel of the Sugden itself would have measured differently to the other - particually in the Treble.
Even with the new caps installed , as they are Electrolytics they will not be identical sample to sample for caps of the same value ,
thus , do all the measuring using ONE channel of the amplifier for all drivers ,
or at least for all drivers of the same type.
Eg: you may find your HF2000 tweeters are not as different to each other after you measure both using the same channel of the amplfier.
One needs to ensure one is measuring the differences between the drivers.
Later one can measure to find if any degree of difference between channels of the ampifier ...
and for that I recommend using a 10 watt 6.8 ohm wirewound resistor for the basic measurement for reference to Celestion 66 impedances.
Use same sample of the resistor to measure each channel of the amp.
Use sufficient power from the amp for the resistor to get slightly warm to touch - not hot , nor cold.
If you want to measure for higher power output level differences you will have to buy 20 or 25 watt or higher power resistors ,
or Parallel connect several 10 watters - which is what I do.
Amplifiers that measure close to identical channel to channel into Resistive loads sometimes do not into Reactive loads.
To test into a reactive load , connect the 6.8 ohm resistor to the output of one Celestion midrange filter , and 4.7 ohm/10 watts to outputs of its woofer and tweeter filters ,
and use that one test filter to measure each channel of the amplifier.
Here you will not get equal output across the full frequency bandwidth.
What one needs to do here is look at the relative output of each channel versus the other at the same frequency for all the measured frequencies.
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