Cabinet Dampening
Hi Lucas,
I'm glad you've brought the subject of 'Cabinet Damping'. I have previously installed some damping pads on the lower inside panels i.e. around the bass and mid-range driver. I have also got some more to finish, dampening all of the exposed internal panels. I purchased them from our good friends Wilmslow Audio. The are 'Acoustic Laminate Panel 10mm Acoustic Foam on a 2mm Self-adhesive bitumen backing 300x200x12mm' and they seem to do a very good job. Although they fit centrally on each panel with a small gap all the way around. I have also purchased some BAF Wadding 'Bonded acetate fibre - used for controlling standing waves' to use when I've finally finished my upgrades. As I said the Acoustic panels do leave a gap around the edges on each panel but do seem to effective dampening! I know this is nit picking but do you think I should cover all of the internal panels, leaving not bare wooden surfaces at all?
I am waiting for Alan to get back to me regarding the components required and which need ordering, I hope I have given him all of the information he requires as hes does appear to be strapped for time!
Regards
Wayne
Hi Lucas,
I'm glad you've brought the subject of 'Cabinet Damping'. I have previously installed some damping pads on the lower inside panels i.e. around the bass and mid-range driver. I have also got some more to finish, dampening all of the exposed internal panels. I purchased them from our good friends Wilmslow Audio. The are 'Acoustic Laminate Panel 10mm Acoustic Foam on a 2mm Self-adhesive bitumen backing 300x200x12mm' and they seem to do a very good job. Although they fit centrally on each panel with a small gap all the way around. I have also purchased some BAF Wadding 'Bonded acetate fibre - used for controlling standing waves' to use when I've finally finished my upgrades. As I said the Acoustic panels do leave a gap around the edges on each panel but do seem to effective dampening! I know this is nit picking but do you think I should cover all of the internal panels, leaving not bare wooden surfaces at all?
I am waiting for Alan to get back to me regarding the components required and which need ordering, I hope I have given him all of the information he requires as hes does appear to be strapped for time!
Regards
Wayne
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I think if you're going to go to all the bother of installing these panels, which are excellent by the way, you should probably go into the corners, as ideally the corners would be rounded on the inside anyway, acoustically speaking (and structurally as it happens). Leaving them uncovered would be the opposite of that, creating tiny pockets for vibrations to bounce around in.
Hi Alan,
How are you? I was wondering if you have had any time to look at my crossover updates? Di you agree with Lucas regarding the 'Jantzen' Caps? I have also been looking at the 'ClarityCap' range as well. I must say they do look pretty impressive on paper!.
Best Regards
Wayne
Look at these
Hi Wayne,
I apologize I have very little time available till next week.
For now have a look at:- Sonic Craft High-End DIY Audio Parts
and at their Sonicap GEN I capacitors.
At USD 146.20 total for mids and treble, these seem to be within your budget,
along with cheaper OK caps from elsewhere for the bass section for total of USD 55.68.
I'll post about why those next time, but if those caps are over-budget, then Post here.
I'll Post a list of what you need, plus the resistor values next week,
plus I'll rely then to the other interim comments since my last posting here,
I hope !
Hi Wayne,
I apologize I have very little time available till next week.
For now have a look at:- Sonic Craft High-End DIY Audio Parts
and at their Sonicap GEN I capacitors.
At USD 146.20 total for mids and treble, these seem to be within your budget,
along with cheaper OK caps from elsewhere for the bass section for total of USD 55.68.
I'll post about why those next time, but if those caps are over-budget, then Post here.
I'll Post a list of what you need, plus the resistor values next week,
plus I'll rely then to the other interim comments since my last posting here,
I hope !
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If that's within your budget, they certainly sound like they ill be good. I've heard good things about them too. Alan's also right about not needing such fancy caps for the bass section, where it is the inductors only that are in the direct signal path, and the caps merely shunt to earth. Jantzens or almost any other film cap would certainly be fine for those.
Hi Alan,
Yes I've had a quick look at the Sonic Craft Sonicap GEN 1 range, and some of their reviews. They look good to me and will be inside my budget, therefore would be happy for you to specify which components I need to order. The ordering process seems fairly straight forward so shouldn't have a problem there!
Are you looking at changing the inductors? if so perhaps you could have a quick look at the questions previously raised i.e. The 'bobbin' type cores, steel bolts and the mounting positions.
Will I be able to retain the original Point to Point crossover boards? I guess I would need new fixing locations for the addional resistors?
Best Regards
Wayne
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Let me know if I'm butting in uninvited, but I feel obliged to repeat this small piece of advice based on experience:
Seriously, do this in a second stage, if at all. If you change all of the caps and inductors at once, it will be very hard to determine what component is making things sound cookie when you first wire it up, particularly as you are adding a new tweeter that needs integrating. To make tiny improvements in the inductors will mean going for inductors with a lower resistance, but that will have a knock on effect on the balance of the whole circuit. It is reasonably likely that one or two resistors at least will need a value change, but determining which and by how much then becomes very complex with so many new parts to integrate, so beware...
Hi Lucas,
You're right! I realise now why replacing the inductors at the same time would introduce too many other variables whilst testing.
Regards
Wayne
Celestion Ditton 66 brochure circa 1973
I've scanned the technical/sales brochure for the Celestion Ditton 66's I obtained in about 1974/75 when I purchased my pair of 66's.
It can be found here:
www.drop.io/Celestion_Ditton_66_brochure
I've scanned the technical/sales brochure for the Celestion Ditton 66's I obtained in about 1974/75 when I purchased my pair of 66's.
It can be found here:
www.drop.io/Celestion_Ditton_66_brochure
Ditton 66 Frequency Response plot in Celestion brochure, + 4 Channel sound
Hi DennyG,
great stuff !
- that Celestion Ditton 66 brochure - I have lost mine, thus it was good to see again to remind me.
On Page 4, the Frequency Response plot seems to be measured at the centre of the midrange dome height/axis, as the plot displays the various perturbations of the MD500 very much the same as sba's plots earlier in this thread, and it is good to have both for comparison/confirmation.
It was the usual practice in that era to measure 3-ways on centre of midrange axis,
{and 2-ways on mid-point between woofer and tweeter, and I wish manufacturers and reviewers would do the same now instead of measuring on centre of tweeter axis !}.
It also shows very good integration with the tweeter around the 5kHz crossover region,
and the expected small roll-off of treble above 10kHz from that tweeter being a little above the measurement axis ...
and that correlates with comments from at least 2 owners in this thread to date about the treble level.
The 500 Hz crossover region looks as good as one can reasonably expect from combining a large cone bass and a dome mid and measuring above the centre of the cone's axis -{as seems to be the case here, unless this plot is a splicing together of 2 plots, with the 2nd measured on centre axis of the bass cone}.
Which crossover board version is in your 66s Denny ?
{See the various photos posted by sba and others at a few places earlier in this thread.}
Thankyou for posting this information, and what is your interest here - are you intending to replace the old capacitors, or ?
***************
Hi ittf,
have a look at the new model NAD C245BEE power amplifier.
It can be configured for 4 discrete channels, and is reasonably priced.
If your room is is not huge it will likely drive 2 pairs of 66s well,
and it can probably be driven from preamp-out or tape-out sockets of your existing amplifier.
NADs usually sound better than most other amps in the same price ranges.
Hi DennyG,
great stuff !
- that Celestion Ditton 66 brochure - I have lost mine, thus it was good to see again to remind me.
On Page 4, the Frequency Response plot seems to be measured at the centre of the midrange dome height/axis, as the plot displays the various perturbations of the MD500 very much the same as sba's plots earlier in this thread, and it is good to have both for comparison/confirmation.
It was the usual practice in that era to measure 3-ways on centre of midrange axis,
{and 2-ways on mid-point between woofer and tweeter, and I wish manufacturers and reviewers would do the same now instead of measuring on centre of tweeter axis !}.
It also shows very good integration with the tweeter around the 5kHz crossover region,
and the expected small roll-off of treble above 10kHz from that tweeter being a little above the measurement axis ...
and that correlates with comments from at least 2 owners in this thread to date about the treble level.
The 500 Hz crossover region looks as good as one can reasonably expect from combining a large cone bass and a dome mid and measuring above the centre of the cone's axis -{as seems to be the case here, unless this plot is a splicing together of 2 plots, with the 2nd measured on centre axis of the bass cone}.
Which crossover board version is in your 66s Denny ?
{See the various photos posted by sba and others at a few places earlier in this thread.}
Thankyou for posting this information, and what is your interest here - are you intending to replace the old capacitors, or ?
***************
Hi ittf,
have a look at the new model NAD C245BEE power amplifier.
It can be configured for 4 discrete channels, and is reasonably priced.
If your room is is not huge it will likely drive 2 pairs of 66s well,
and it can probably be driven from preamp-out or tape-out sockets of your existing amplifier.
NADs usually sound better than most other amps in the same price ranges.
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The Resistors for SEAS tweeter modified 66, and Farnell UK
Thankyou Lucas ... I agree entirely, and usually proceed that way myself.
***************
Hi Wayne, and to any other UK readers ...
one problem with buying resistors from Farnell is that for a lot of the values in the power ratings wanted for this project one has to buy not only in Minimum of 5 pieces, but also in Multiples of 5 pieces ... thus one cannot simply buy 6 pieces, for example.
Another problem is that some of the well-specified resistors have to be imported from the USA, and that adds 15.95 to the price of the Order,
THUS, I will here list UK sourced resistors, and in types that the Quantities can be used.
LIST:
1 ohm - buy the 5 quantity of Welwyn wirewound in WP4S preferably, or in W22 if no stock of WP4S.
Two will be used in the two bass filters and two will be used with the SEAS H737 tweeters, leaving one spare ... in case a faulty sample.
1.8 ohm - buy the 5 in WP4S, {or in W22 if necessary}.
Two will be used in the midrange filter, and two in the bass filter ... instead of the 1.5 ohm I previously specified for there,
because 1.5 was simply the minimum for that position - 1.8 ohm will be no less good there, and perhaps better.
2.7 ohm - will have to be bought in the 5 quantity of WP4S, {or W22 if nec.},
unless you buy a physically larger resistor - 8mm Dia. x 38mm Body Length in W23 - , or something less well specified,
or buy from USA/Canada.
2.7 ohm is now what I think may be better in the midrange filter in Series with the 3.9uF cap, than the larger resistance I specified previously,
after reading two users' later reports in this thread.
In your case Wayne, you may need to use a 2.7 ohm with each of the L-pads you buy later for your Realistic super-tweeter,
thus the extras may not be wasted.
15 ohm - for SEAS tweeter attenuation - single quantities can be bought in Welwyn W23, and that is the minimum power sized resistor I think sensible to install for the Parallel arm of the attenuation L-pad there,
however buy 4 pieces Wayne - so that you can measure and choose a close-to-Pair for the tweeters and have another close-to-Pair to use in Parallel to form a 7.5 ohm load resistor you may need for a measurement circuit later when trying to work out how to best decide what crossover components are needed for the Realistic super-tweeter - I will describe that then.
10 ohm/0.1% for Calibration/accuracy determination for the Maplin UT50A multimeter.
Buy 2 pieces, because one could be faulty, or inadvertantly lost at some time.
Buy the Order Code: 1754854 of the Tyco/Neohm because it is a little larger than the 1754843 version, thus easier to handle, and only costs a few pence more.
Alternately, buy the 5 minimum of Order Code 1083036 of Tyco, which at 81p each is lower price than 2 of the others, if you want cheaper and don't mind handling small size.
{The others I had previously alluded to are from USA and have a 15.95 surcharge !}
All the above may still be less than Farnell's minimum Charge per Order,
thus useful for you Wayne will be 100 ohm in +/- 0.1% so you can determine the accuracy of the next higher range of your multimeter.
Buy 2 of either Order Code:
9499865 - Welwyn , or 1754857 - Tyco/Neohm.
The cheaper Welwyn will be OK - the other is simply an alternate.
And if still need to buy to fill the minimum price, then a Pair of higher power wirewounds may be useful for test loads for other possibilities that may occur.
Two of Welwyn W24 series in 4.7 ohms is likely to be the most useful if necessary for the Celestions.
If that is not enough to fill the minimum price, well Post here and I'll think of a few other things possibly useful ...
or buy some good quality Solder of the optimum alloy ratio for low melting point/fast to solidify - look for the word "eutectic".
{A Silver loaded solder is not necessary, nor always optimum. The old 63/37, Tin/Lead formula was good, but now we are not supposed to use Lead containing solders ... well I'm glad I still have some !}.
When the resistors arrive use some small pieces of paper to stick on each as a label for after you measure each.
Estabish the accuracy of your multimeter with the +/- 0.1% 10 ohm resistor.
First subtract the ~ 0.2ohm of the test leads from the display reading, and then what-ever deviation from 10 ohms will be the error of the internals of the particular sample of your meter.
Write it down somewhere ... and this error may change over time as the meter's internals drift, thus check it each time you use the low ohms range of the meter.
{Same for the next range with the +/- 0.1% 100 ohm resistor, when you use the next range.
You will not likely need accuracy determination for the higher ranges, except the very highest, but I doubt you'll ever need to critically use that range.}
Low resistances draw a lot of current from the battery, thus it can soon go flat.
To extend life, measure quickly - holding contact only till the display stabilizes.
Measure the highest resistances first, and the lowest last,
that is: 15 --> 2.7 --> 1.8 --> 1 ohm, via whatever others you may have bought, and label each with its exact reading so that you don't have to do it all again.
Measure also the DC resistances of both SEAS tweeters, and of the Realistic tweeters again.
From each display reading:
Subtract the deviation you saw from the 10 ohm calibration resistor, {eg: if 10.2 or 10.3, etc ...}
If the 10 ohm gave a -ive reading, {eg: 9.9 or 9.8}, then Add the deviation from 10.
I recommend you write these corrected figures on the labels.
***************
Next, make up the L-pads for the SEAS tweeters:
Connect the 15 ohm resistor across the tweeter output terminals of the crossover board.
Connect the 1 ohm resistor between the cluster of caps that sum to 6uF and the output terminal that this caps' cluster is currently connected to,
that is you will be disconnecting the caps' cluster at the output end of the crossover and installing the 1 ohm resistor there.
Look back to Page 43, # 429, in this thread at the 2nd Photo that moermusic posted of his capacitor-resistor connection if you are not sure.
BEFORE you disconnect the Realistic tweeter, look to see which Polarity it was connected in.
Does it have its + connected to the + or - output of the crossover ?
This is important for me to know so that I can better understand this type of treble sound you want to achieve.
Celestion connected their tweeter in Reverse Polarity: + output to tweeter -, and - output to tweeter +.
Do that for the SEAS for initial listening, but tell me how the Realistic was connected.
A 3rd Order filter, which this treble filter is, can be connected in either option of Polarity.
There is reason for one or the other, but some listeners prefer the opposite.
Do not reverse the Polarity of the woofer or the mid-dome, because for the lower crossover point the filters are a + to + connection type,
and the sound will be very peculiar if Polarity is reversed there.
Post your resistors' measurements please, because those may be useful for other readers,
and I need to know the measurements for each SEAS and each Realistic tweeter, with accuracy correction via the +/- 0.1% 10 ohm resistor.
Post your listening impressions after a few days with the SEAS installed,
and then we'll proceed to the capacitors.
Thankyou Lucas ... I agree entirely, and usually proceed that way myself.
***************
Hi Wayne, and to any other UK readers ...
one problem with buying resistors from Farnell is that for a lot of the values in the power ratings wanted for this project one has to buy not only in Minimum of 5 pieces, but also in Multiples of 5 pieces ... thus one cannot simply buy 6 pieces, for example.
Another problem is that some of the well-specified resistors have to be imported from the USA, and that adds 15.95 to the price of the Order,
THUS, I will here list UK sourced resistors, and in types that the Quantities can be used.
LIST:
1 ohm - buy the 5 quantity of Welwyn wirewound in WP4S preferably, or in W22 if no stock of WP4S.
Two will be used in the two bass filters and two will be used with the SEAS H737 tweeters, leaving one spare ... in case a faulty sample.
1.8 ohm - buy the 5 in WP4S, {or in W22 if necessary}.
Two will be used in the midrange filter, and two in the bass filter ... instead of the 1.5 ohm I previously specified for there,
because 1.5 was simply the minimum for that position - 1.8 ohm will be no less good there, and perhaps better.
2.7 ohm - will have to be bought in the 5 quantity of WP4S, {or W22 if nec.},
unless you buy a physically larger resistor - 8mm Dia. x 38mm Body Length in W23 - , or something less well specified,
or buy from USA/Canada.
2.7 ohm is now what I think may be better in the midrange filter in Series with the 3.9uF cap, than the larger resistance I specified previously,
after reading two users' later reports in this thread.
In your case Wayne, you may need to use a 2.7 ohm with each of the L-pads you buy later for your Realistic super-tweeter,
thus the extras may not be wasted.
15 ohm - for SEAS tweeter attenuation - single quantities can be bought in Welwyn W23, and that is the minimum power sized resistor I think sensible to install for the Parallel arm of the attenuation L-pad there,
however buy 4 pieces Wayne - so that you can measure and choose a close-to-Pair for the tweeters and have another close-to-Pair to use in Parallel to form a 7.5 ohm load resistor you may need for a measurement circuit later when trying to work out how to best decide what crossover components are needed for the Realistic super-tweeter - I will describe that then.
10 ohm/0.1% for Calibration/accuracy determination for the Maplin UT50A multimeter.
Buy 2 pieces, because one could be faulty, or inadvertantly lost at some time.
Buy the Order Code: 1754854 of the Tyco/Neohm because it is a little larger than the 1754843 version, thus easier to handle, and only costs a few pence more.
Alternately, buy the 5 minimum of Order Code 1083036 of Tyco, which at 81p each is lower price than 2 of the others, if you want cheaper and don't mind handling small size.
{The others I had previously alluded to are from USA and have a 15.95 surcharge !}
All the above may still be less than Farnell's minimum Charge per Order,
thus useful for you Wayne will be 100 ohm in +/- 0.1% so you can determine the accuracy of the next higher range of your multimeter.
Buy 2 of either Order Code:
9499865 - Welwyn , or 1754857 - Tyco/Neohm.
The cheaper Welwyn will be OK - the other is simply an alternate.
And if still need to buy to fill the minimum price, then a Pair of higher power wirewounds may be useful for test loads for other possibilities that may occur.
Two of Welwyn W24 series in 4.7 ohms is likely to be the most useful if necessary for the Celestions.
If that is not enough to fill the minimum price, well Post here and I'll think of a few other things possibly useful ...
or buy some good quality Solder of the optimum alloy ratio for low melting point/fast to solidify - look for the word "eutectic".
{A Silver loaded solder is not necessary, nor always optimum. The old 63/37, Tin/Lead formula was good, but now we are not supposed to use Lead containing solders ... well I'm glad I still have some !}.
When the resistors arrive use some small pieces of paper to stick on each as a label for after you measure each.
Estabish the accuracy of your multimeter with the +/- 0.1% 10 ohm resistor.
First subtract the ~ 0.2ohm of the test leads from the display reading, and then what-ever deviation from 10 ohms will be the error of the internals of the particular sample of your meter.
Write it down somewhere ... and this error may change over time as the meter's internals drift, thus check it each time you use the low ohms range of the meter.
{Same for the next range with the +/- 0.1% 100 ohm resistor, when you use the next range.
You will not likely need accuracy determination for the higher ranges, except the very highest, but I doubt you'll ever need to critically use that range.}
Low resistances draw a lot of current from the battery, thus it can soon go flat.
To extend life, measure quickly - holding contact only till the display stabilizes.
Measure the highest resistances first, and the lowest last,
that is: 15 --> 2.7 --> 1.8 --> 1 ohm, via whatever others you may have bought, and label each with its exact reading so that you don't have to do it all again.
Measure also the DC resistances of both SEAS tweeters, and of the Realistic tweeters again.
From each display reading:
Subtract the deviation you saw from the 10 ohm calibration resistor, {eg: if 10.2 or 10.3, etc ...}
If the 10 ohm gave a -ive reading, {eg: 9.9 or 9.8}, then Add the deviation from 10.
I recommend you write these corrected figures on the labels.
***************
Next, make up the L-pads for the SEAS tweeters:
Connect the 15 ohm resistor across the tweeter output terminals of the crossover board.
Connect the 1 ohm resistor between the cluster of caps that sum to 6uF and the output terminal that this caps' cluster is currently connected to,
that is you will be disconnecting the caps' cluster at the output end of the crossover and installing the 1 ohm resistor there.
Look back to Page 43, # 429, in this thread at the 2nd Photo that moermusic posted of his capacitor-resistor connection if you are not sure.
BEFORE you disconnect the Realistic tweeter, look to see which Polarity it was connected in.
Does it have its + connected to the + or - output of the crossover ?
This is important for me to know so that I can better understand this type of treble sound you want to achieve.
Celestion connected their tweeter in Reverse Polarity: + output to tweeter -, and - output to tweeter +.
Do that for the SEAS for initial listening, but tell me how the Realistic was connected.
A 3rd Order filter, which this treble filter is, can be connected in either option of Polarity.
There is reason for one or the other, but some listeners prefer the opposite.
Do not reverse the Polarity of the woofer or the mid-dome, because for the lower crossover point the filters are a + to + connection type,
and the sound will be very peculiar if Polarity is reversed there.
Post your resistors' measurements please, because those may be useful for other readers,
and I need to know the measurements for each SEAS and each Realistic tweeter, with accuracy correction via the +/- 0.1% 10 ohm resistor.
Post your listening impressions after a few days with the SEAS installed,
and then we'll proceed to the capacitors.
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An amazingly uninspired review at the end there. Not exactly raving, like they seem to about everything that comes out these days. I guess back then, there was more honesty and less sensationalism and capitalist influence.
Back Again
I just tried to "drop" in a pair of these. Thought in 5 minutes would have a listen & compare to the hf2000's. Gonna have to wait for another day (maybe tomorrow) so as to take time to make BIGGER hole so they fit.! Did yoiur Seas terminals indicate which is hot and ground? I have the PCC board with a 3.9uf at C3&4; a 6uf at C1&2 with a .5 R in series here. What if any resistor do you have here?
I just tried to "drop" in a pair of these. Thought in 5 minutes would have a listen & compare to the hf2000's. Gonna have to wait for another day (maybe tomorrow) so as to take time to make BIGGER hole so they fit.! Did yoiur Seas terminals indicate which is hot and ground? I have the PCC board with a 3.9uf at C3&4; a 6uf at C1&2 with a .5 R in series here. What if any resistor do you have here?
Celestion Ditton 66 brochure circa 1973
Hi Alan,
Yes I'm intending to update my crossovers. My 66's are hard wired with the tagged board (T.B.C.). They have a beautiful walnut veneer finish and a black speaker panel. The midrange units are MD 500's.
Some 20 years ago I realised they had lost some musicality and read somewhere about improvements that could be expected by replacing the capacitors. I replaced the caps with Solen products but I'm not sure of the type. They look like Solen's current metallized polypropylene model. The change was not a major step up, and certainly didn't bring them back to original, but that is where I stopped the upgrading process. Wish I had the knowledge then about the resistors. I anticipate I'll soon replace the caps with better sounding ones and apply your recommendations regarding the resistors. I think Clarity Cap PX may be worth a try.
I've also got a pair of MD500's in a bespoke speaker system I purchased recently which needs new crossovers as they are prototypes and have some electrolytics (the speaker designer/builder never got to build final crossovers). I've used Speaker Workshop software to do some measurements on the drivers in this system and on the drivers in one 66. This is a bit of a hobby and I'm basically learning as I go along. I will also try other software when I get back to the project proper. All the drivers tested so far are ok impedance wise, except for one of the tweeters in the bespoke system which was easy to replace, so it all looks positive.
My approach will probably be to finalise the 66 crossover using the advice in this thread and also using perhaps both objective and subjective tests and then try this crossover in the bespoke system to see how that system measures and sounds. The mids and tweets will probably need attenuation as per the prototype design. I've already swapped the 66 crossover into the bespoke unit and the (nasal?, hollow?) character of the crossover was apparent there as well so the 66 crossovers definitely need revision. My intention is to also rebuild the 2nd order bespoke crossovers with new caps and resistors and see if they are better than the 66 crossovers in that application.
Thanks for your advice and all the input from the other participants.
DG
Hi Alan,
Yes I'm intending to update my crossovers. My 66's are hard wired with the tagged board (T.B.C.). They have a beautiful walnut veneer finish and a black speaker panel. The midrange units are MD 500's.
Some 20 years ago I realised they had lost some musicality and read somewhere about improvements that could be expected by replacing the capacitors. I replaced the caps with Solen products but I'm not sure of the type. They look like Solen's current metallized polypropylene model. The change was not a major step up, and certainly didn't bring them back to original, but that is where I stopped the upgrading process. Wish I had the knowledge then about the resistors. I anticipate I'll soon replace the caps with better sounding ones and apply your recommendations regarding the resistors. I think Clarity Cap PX may be worth a try.
I've also got a pair of MD500's in a bespoke speaker system I purchased recently which needs new crossovers as they are prototypes and have some electrolytics (the speaker designer/builder never got to build final crossovers). I've used Speaker Workshop software to do some measurements on the drivers in this system and on the drivers in one 66. This is a bit of a hobby and I'm basically learning as I go along. I will also try other software when I get back to the project proper. All the drivers tested so far are ok impedance wise, except for one of the tweeters in the bespoke system which was easy to replace, so it all looks positive.
My approach will probably be to finalise the 66 crossover using the advice in this thread and also using perhaps both objective and subjective tests and then try this crossover in the bespoke system to see how that system measures and sounds. The mids and tweets will probably need attenuation as per the prototype design. I've already swapped the 66 crossover into the bespoke unit and the (nasal?, hollow?) character of the crossover was apparent there as well so the 66 crossovers definitely need revision. My intention is to also rebuild the 2nd order bespoke crossovers with new caps and resistors and see if they are better than the 66 crossovers in that application.
Thanks for your advice and all the input from the other participants.
DG
Ah, yes. I should have mentioned that the hole would need opening up with a jigsaw. Sorry about that. It's worth it though.
Examine them really closely with a light and you will find the + symbol stamped in somewhere. Remember to keep polarity reversed, at least until you've had a good listen. I don't have a resistor there yet. I have Celestion 44s though, so better to ask somebody else about resistors.
Canada and USA - resistors for SEAS, and other topics
Hi Doug,
if I had known you were intending to upgrade tweeters I would have recommended you consider the Audax TWO25A2 that sba posted the data about in #532 on Page 54,
because of what you earlier stated about your hearing and treble frequencies,
however you may like the SEAS, and I hope you do, and the widening for hole for it does not require as much as for the Audax.
For Resistors for the SEAS, use the values I specified in #592 above,
{but not those if you decide to exchange for the Audax}.
In Canada/USA you can easily get the Mills MRA-5, and I think you already have some of those ...
Use 1 ohm in MRA-5 for the Series resistor, but keep your 0.5 ohm in case they need to be used later.
For the Parallel resistor greater than 5 watts is advisable.
Buy at least 7 watts, and up to 10 watts if size not too large to fit.
Look for a well specified Ohmite or Dale {now Vishay-Dale} wirewound for the 15 ohm -
{"well specified" includes Temp. Co. rating of no greater than 200ppm/degrees C, and less if possible}.
It does not need to be non-inductive, but as non-inductives are usually well-made, using such is fine if you want to.
Keep watching this thread - I will be posting about capacitors for use with the SEAS soon, but first listen with the ones you have.
These will not give ideal response, but it is useful to listen to changes stage-by-stage.
Also Doug,
given your report of upper midrange dominating the sound ... dloper has not returned yet with any further about attenuation experiments for midrange, however I have another idea which may help - if your domes are the MD version .. ?
Whilst you are buying resistors for the SEAS, look for 82 ohms wirewound in 10 watts {or not too much less power rating}.
These do not need to be non-inductive, but OK if are as for the 15 ohm, and look in Ohmite or Vishay/Dale.
Farnell likely sell those cheaper where you are, as may other retailers - eg: "Mouser" and "Digikey"
... I have forgotten the names of the other mail-order sellers there.
If you have the MD500 dome, buy two of 82 ohms, then Post here and I'll describe the application.
You can change your two midrange resistors to the values I specified in #592 above if you want to,
or wait to see what dloper may report later.
***************
Wayne, and others ...
I forgot to include yesterday,
when using low resistance values it is vital that the connections be electrically clean - especially for treble frequencies,
thus do not rely on the Rosin in the solder to entirely clean the resistors' leads.
Scrape-clean the section of the wire that you will be soldering.
Keep the connection area {length of wire under solder} short, and do not inadvertantly make Inductors with the connections by twisting the wires together for significant length !
Hi Doug,
if I had known you were intending to upgrade tweeters I would have recommended you consider the Audax TWO25A2 that sba posted the data about in #532 on Page 54,
because of what you earlier stated about your hearing and treble frequencies,
however you may like the SEAS, and I hope you do, and the widening for hole for it does not require as much as for the Audax.
For Resistors for the SEAS, use the values I specified in #592 above,
{but not those if you decide to exchange for the Audax}.
In Canada/USA you can easily get the Mills MRA-5, and I think you already have some of those ...
Use 1 ohm in MRA-5 for the Series resistor, but keep your 0.5 ohm in case they need to be used later.
For the Parallel resistor greater than 5 watts is advisable.
Buy at least 7 watts, and up to 10 watts if size not too large to fit.
Look for a well specified Ohmite or Dale {now Vishay-Dale} wirewound for the 15 ohm -
{"well specified" includes Temp. Co. rating of no greater than 200ppm/degrees C, and less if possible}.
It does not need to be non-inductive, but as non-inductives are usually well-made, using such is fine if you want to.
Keep watching this thread - I will be posting about capacitors for use with the SEAS soon, but first listen with the ones you have.
These will not give ideal response, but it is useful to listen to changes stage-by-stage.
Also Doug,
given your report of upper midrange dominating the sound ... dloper has not returned yet with any further about attenuation experiments for midrange, however I have another idea which may help - if your domes are the MD version .. ?
Whilst you are buying resistors for the SEAS, look for 82 ohms wirewound in 10 watts {or not too much less power rating}.
These do not need to be non-inductive, but OK if are as for the 15 ohm, and look in Ohmite or Vishay/Dale.
Farnell likely sell those cheaper where you are, as may other retailers - eg: "Mouser" and "Digikey"
... I have forgotten the names of the other mail-order sellers there.
If you have the MD500 dome, buy two of 82 ohms, then Post here and I'll describe the application.
You can change your two midrange resistors to the values I specified in #592 above if you want to,
or wait to see what dloper may report later.
***************
Wayne, and others ...
I forgot to include yesterday,
when using low resistance values it is vital that the connections be electrically clean - especially for treble frequencies,
thus do not rely on the Rosin in the solder to entirely clean the resistors' leads.
Scrape-clean the section of the wire that you will be soldering.
Keep the connection area {length of wire under solder} short, and do not inadvertantly make Inductors with the connections by twisting the wires together for significant length !
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more Resistors' installation
Hi DennyG,
I advise you install the ESR simulating resistors in the midrange filter, and in the bass filter section if you have polypropylene caps there also.
No resistor is needed in the treble filter for HF2000, unless you want a milder sound.
Better results can be got with some other brands of capacitors than Solen, but listen with the resistors in before you decide about replacing the capacitors.
Some of the audible problems with Solens may be batch related, thus yours may be OK, or less so ...
What cap values do you have in the bass filter ?
I do not know the extent of availability of parts in Australia, though my cousin there buys his capacitors via Mail-order from USA,
as he says the range of values is not wide from the Australian sellers he knows of ... at least for the reasonably priced brands.
For resistors, buy in whatever brands you can of those I listed in #592 and #597 above.
***************
Hi Lucas,
as you are reading in this thread, I hope you have noticed I've re-thought the power rating for the 15 ohm resistor for the SEAS,
thus if you have not yet bought, then buy in W23 and not in W22 series Welwyn.
If you have bought and installed, what are your findings about the sound now ?
I'll try to get back to the other thread to resume replying to unanswered matters there soon, but I have to log-off now unfortunately.
Hi DennyG,
I advise you install the ESR simulating resistors in the midrange filter, and in the bass filter section if you have polypropylene caps there also.
No resistor is needed in the treble filter for HF2000, unless you want a milder sound.
Better results can be got with some other brands of capacitors than Solen, but listen with the resistors in before you decide about replacing the capacitors.
Some of the audible problems with Solens may be batch related, thus yours may be OK, or less so ...
What cap values do you have in the bass filter ?
I do not know the extent of availability of parts in Australia, though my cousin there buys his capacitors via Mail-order from USA,
as he says the range of values is not wide from the Australian sellers he knows of ... at least for the reasonably priced brands.
For resistors, buy in whatever brands you can of those I listed in #592 and #597 above.
***************
Hi Lucas,
as you are reading in this thread, I hope you have noticed I've re-thought the power rating for the 15 ohm resistor for the SEAS,
thus if you have not yet bought, then buy in W23 and not in W22 series Welwyn.
If you have bought and installed, what are your findings about the sound now ?
I'll try to get back to the other thread to resume replying to unanswered matters there soon, but I have to log-off now unfortunately.
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SEAS
After looking with a 10 x magnifier and sunlight, I still could not determine polarity. Could you verbally or pictorally show which is which?
Alan: I had not planned to put in the SEAS. Just a spur of the moment thing. Thought I'd try & see if I could hear more of the upper end with them.
Will study your post 592. Thought might be only minor changes needed in tweet filter. Not making L pads. At present: C1&2 - single Clarity 6.0 uf with a 0.5 r; C3&4 - single 3.9 Clarity; C5 - 3.9 Clarity with a 3.3 r; C6 - a 68uf Solen with a 1.5r; C7 - Clarity 25uf with a 1.8r; C8 - a 75 Solen with a 1.0 r.
Ah, yes. I should have mentioned that the hole would need opening up with a jigsaw. Sorry about that. It's worth it though.
Examine them really closely with a light and you will find the + symbol stamped in somewhere. Remember to keep polarity reversed, at least until you've had a good listen. I don't have a resistor there yet. I have Celestion 44s though, so better to ask somebody else about resistors.
After looking with a 10 x magnifier and sunlight, I still could not determine polarity. Could you verbally or pictorally show which is which?
Alan: I had not planned to put in the SEAS. Just a spur of the moment thing. Thought I'd try & see if I could hear more of the upper end with them.
Will study your post 592. Thought might be only minor changes needed in tweet filter. Not making L pads. At present: C1&2 - single Clarity 6.0 uf with a 0.5 r; C3&4 - single 3.9 Clarity; C5 - 3.9 Clarity with a 3.3 r; C6 - a 68uf Solen with a 1.5r; C7 - Clarity 25uf with a 1.8r; C8 - a 75 Solen with a 1.0 r.
Resistor installation and source of parts
Thanks Alan,
Adding the resistors first is a good idea. I can easily test the modified crossover in the bespoke units first to see if the overall sound character of the mid range improves (I've named them PTB's - the designer's initials). The PTB's were built with the crossover located externally which makes experimentation like this easy to do.
The cap values in the bass filter are difficult to read now but they are most probably 80mF. I doubt if they are 60mF but the printing is, unfortunately, not very clear.
Where does your cousin mail order parts from in the USA? This may be the best way to buy them.
DG
Thanks Alan,
Adding the resistors first is a good idea. I can easily test the modified crossover in the bespoke units first to see if the overall sound character of the mid range improves (I've named them PTB's - the designer's initials). The PTB's were built with the crossover located externally which makes experimentation like this easy to do.
The cap values in the bass filter are difficult to read now but they are most probably 80mF. I doubt if they are 60mF but the printing is, unfortunately, not very clear.
Where does your cousin mail order parts from in the USA? This may be the best way to buy them.
DG
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