Re: Web-site down last week ?
----> This may seem to be a good idea, based on the information you posted from that web-site, but as the coils in the 66s will interact to some degree with each other it is possible this interaction has been taken into account by Celestion engineers during the fine tuning of the design and layout, thus if so , and you change the separations you will change the inductances and thus the slopes and degree of filtering.
The interactions will not be so large as to be detrimental to good sound in this layout, thus especially for the two bass-filter coils I recommend you leave them placed at the separation they currently are from each other as their interaction with each other may be part of how the filter is working,
and similarly for the two midrange filter coils, though less likely to be the case there,
but you can re-position each pair of coils so that the bass coils and the mid coils are a little further each two from the other two.
The coil that may render best results if moved further from the others is the one in the treble filter, as one does not want magnetic coupling of the lower frequencies into the tweeter circuit.
----> my mistake, I typed "resistors" where I should have typed "capacitors", though you seemed to have realized that, thus this correction is only for any other readers who may be confused.
____________________________________________________
I hope to continue with other matters I started about the reconditioning soon, as unfortunately no more time to today.
sba said:
----> This may seem to be a good idea, based on the information you posted from that web-site, but as the coils in the 66s will interact to some degree with each other it is possible this interaction has been taken into account by Celestion engineers during the fine tuning of the design and layout, thus if so , and you change the separations you will change the inductances and thus the slopes and degree of filtering.
The interactions will not be so large as to be detrimental to good sound in this layout, thus especially for the two bass-filter coils I recommend you leave them placed at the separation they currently are from each other as their interaction with each other may be part of how the filter is working,
and similarly for the two midrange filter coils, though less likely to be the case there,
but you can re-position each pair of coils so that the bass coils and the mid coils are a little further each two from the other two.
The coil that may render best results if moved further from the others is the one in the treble filter, as one does not want magnetic coupling of the lower frequencies into the tweeter circuit.
alan-1-b said:
----> my mistake, I typed "resistors" where I should have typed "capacitors", though you seemed to have realized that, thus this correction is only for any other readers who may be confused.
____________________________________________________
I hope to continue with other matters I started about the reconditioning soon, as unfortunately no more time to today.
the spacing of the Coils
I have looked again at all the Photos of 66 cross-overs posted by Grahame and sba, and specifically at the spacings between the Inductor coils.
For the oldest x-over boards, hardwired, as are sba's Blackies,
AND for the next series of boards, as are sba's Woodies and the spare boards bought by Grahame,
the spacing between the two coils in the bass filter is close enough for there to be some inductive coupling,
however, as I said in my last Post, and in my original Post on this matter {#233 on Page 10}, this coupling may be part of the filter's functioning and perhaps should be left as is, but experiment with wider spacing if you want to and listen to the result.
The larger of the midrange filter's coils is close enough to the largest bass filter coil for there to be inductive coupling, but as this mid-coil is blocking high frequencies and passing low frequencies to ground, the coupling into it from the bass coil will not cause a major problem,
and neither will the coupling of signal from this mid coil to the bass coil.
The smaller of the mid-filter coils is far enough away from both the larger mid-coil and same sized bass-coil for there to be only very small inductive coupling.
This will not cause a significant audible problem,
but if you want to place the small coil further from the others it will not cause any problems, and such may render a small audible improvement.
The Treble filter's coil is far enough away from both mid-filters' coils for very very little inductive coupling, and any will be low midrange frequencies sent to ground, thus it is OK spaced as it is, but you can place it further away if you want to.
****************************************************
Beneficial audible effects of new capacitors and ESR simulating resistors will be greater than beneficial effects of wider spacings between any of the coils, except perhaps between the two bass coils, changing which may render better or may render worse sound - one would have to experiment and listen, but better to do this after you have the new caps and ESR resistors in-circuit.
****************************************************
For the later series 66 cross-overs, as are Grahame's originals, on PCBs with the olive green coloured treble caps,
all the bass and mid filters' coils are more closely spaced than they were on the older boards.
Again, inductive coupling effects between the two bass coils may be intended part of the bass filter's function, thus can be left as is,
but space further if you wish.
Also, inductive coupling between the large mid-coil and the adjacent bass-coil will be as I described above for the older boards.
For the small mid-coil, it is too close to the intermediate sized bass coil.
There will be significant inductive coupling of signal, and a wider spacing of this coil from the larger coil will likely render better audible result, as one does not want low frequencies coupled from the bass-coil into the small mid-coil and from it to the MD500.
Obviously the audible effects are not overwhelmingly large, or many listeners would have commented at the time of issue that the new model was not significantly better than the old model in the midrange, but merely different,
and I think Celestion engineers would have noticed if there was a large audible effect,
though I think it was some-what cynical Economy of Scale and penny-pinching meaness on behalf of the Celestion budget overseer(s) to specify the smaller board, and thus the closer coils' spacing.
The treble-filter coil on this board is sufficient distance from the other coils for there to be no significant audible problems, and any inductively coupled low-mids will be sent to ground through this coil and not to the tweeter {and there is a capacitor between the coil and tweeter to further block low mids}.
****************************************************
Finally, if any-one is disconnecting and re-positioning the coils, do observe my warning about the physical orientation and the co-efficient of coupling of the coils in my Post #233 on Page 10.
That is, do not turn any of the coils upside down, nor connect their leads in the reverse Polarity than they are currently.
Yes, you can stand one or both the smaller coils on their sides if you follow the recommendations in the photos on the troelsgravensen.dk site LINK which sba Posted in #204 on Page 9.
Doing this with the small mid-coil on the later 66 small boards will suffice, rather than have to make a new larger board to otherwise place that coil further from the bass coil.
Copy his placement 6 {Fig.5}, or, angle the small coil slightly so that its edge is still mostly towards the intermediate sized bass-coil but also a little way towards the largest bass-coil, so that it will be partly off the inductive coupling axis' of all the larger coils.
If you do that, the treble filter's coil will be OK left as is.
I have looked again at all the Photos of 66 cross-overs posted by Grahame and sba, and specifically at the spacings between the Inductor coils.
For the oldest x-over boards, hardwired, as are sba's Blackies,
AND for the next series of boards, as are sba's Woodies and the spare boards bought by Grahame,
the spacing between the two coils in the bass filter is close enough for there to be some inductive coupling,
however, as I said in my last Post, and in my original Post on this matter {#233 on Page 10}, this coupling may be part of the filter's functioning and perhaps should be left as is, but experiment with wider spacing if you want to and listen to the result.
The larger of the midrange filter's coils is close enough to the largest bass filter coil for there to be inductive coupling, but as this mid-coil is blocking high frequencies and passing low frequencies to ground, the coupling into it from the bass coil will not cause a major problem,
and neither will the coupling of signal from this mid coil to the bass coil.
The smaller of the mid-filter coils is far enough away from both the larger mid-coil and same sized bass-coil for there to be only very small inductive coupling.
This will not cause a significant audible problem,
but if you want to place the small coil further from the others it will not cause any problems, and such may render a small audible improvement.
The Treble filter's coil is far enough away from both mid-filters' coils for very very little inductive coupling, and any will be low midrange frequencies sent to ground, thus it is OK spaced as it is, but you can place it further away if you want to.
****************************************************
Beneficial audible effects of new capacitors and ESR simulating resistors will be greater than beneficial effects of wider spacings between any of the coils, except perhaps between the two bass coils, changing which may render better or may render worse sound - one would have to experiment and listen, but better to do this after you have the new caps and ESR resistors in-circuit.
****************************************************
For the later series 66 cross-overs, as are Grahame's originals, on PCBs with the olive green coloured treble caps,
all the bass and mid filters' coils are more closely spaced than they were on the older boards.
Again, inductive coupling effects between the two bass coils may be intended part of the bass filter's function, thus can be left as is,
but space further if you wish.
Also, inductive coupling between the large mid-coil and the adjacent bass-coil will be as I described above for the older boards.
For the small mid-coil, it is too close to the intermediate sized bass coil.
There will be significant inductive coupling of signal, and a wider spacing of this coil from the larger coil will likely render better audible result, as one does not want low frequencies coupled from the bass-coil into the small mid-coil and from it to the MD500.
Obviously the audible effects are not overwhelmingly large, or many listeners would have commented at the time of issue that the new model was not significantly better than the old model in the midrange, but merely different,
and I think Celestion engineers would have noticed if there was a large audible effect,
though I think it was some-what cynical Economy of Scale and penny-pinching meaness on behalf of the Celestion budget overseer(s) to specify the smaller board, and thus the closer coils' spacing.
The treble-filter coil on this board is sufficient distance from the other coils for there to be no significant audible problems, and any inductively coupled low-mids will be sent to ground through this coil and not to the tweeter {and there is a capacitor between the coil and tweeter to further block low mids}.
****************************************************
Finally, if any-one is disconnecting and re-positioning the coils, do observe my warning about the physical orientation and the co-efficient of coupling of the coils in my Post #233 on Page 10.
That is, do not turn any of the coils upside down, nor connect their leads in the reverse Polarity than they are currently.
Yes, you can stand one or both the smaller coils on their sides if you follow the recommendations in the photos on the troelsgravensen.dk site LINK which sba Posted in #204 on Page 9.
Doing this with the small mid-coil on the later 66 small boards will suffice, rather than have to make a new larger board to otherwise place that coil further from the bass coil.
Copy his placement 6 {Fig.5}, or, angle the small coil slightly so that its edge is still mostly towards the intermediate sized bass-coil but also a little way towards the largest bass-coil, so that it will be partly off the inductive coupling axis' of all the larger coils.
If you do that, the treble filter's coil will be OK left as is.
NEWS FLASH
Hello Hello all,
Been some time, i see SBA's hard at work on those 66's crossovers.
I have just come into possession of brand new NOS & FACTORY REBUILT Ditton 66 components: HF2000's, MD500's, 12IN WOOFERS & RADIATORS with WOODIE STYLE CROSSOVERS, In original boxes, couldn't believe my luck, this lost shippment has been sitting around for perhaps close to 40 years.....did spend some monies......
Anyway, will be giving them a going over real soon (time permitting) and selling what i don't need, looks to be 4 complete sets!!!!
ToneDef2
No i have not forgotten my small roll concerning the baffle defraction issue....sorry for the delay.
Peace
Hello Hello all,
Been some time, i see SBA's hard at work on those 66's crossovers.
I have just come into possession of brand new NOS & FACTORY REBUILT Ditton 66 components: HF2000's, MD500's, 12IN WOOFERS & RADIATORS with WOODIE STYLE CROSSOVERS, In original boxes, couldn't believe my luck, this lost shippment has been sitting around for perhaps close to 40 years.....did spend some monies......
Anyway, will be giving them a going over real soon (time permitting) and selling what i don't need, looks to be 4 complete sets!!!!
ToneDef2
No i have not forgotten my small roll concerning the baffle defraction issue....sorry for the delay.
Peace
What a find! You lucky so-and-so. Even more remarkable if you found them in the USA. Can't be many of those lying around.
I'm really enjoying my bog standard late model woodies, which are only modded to the extent they are re-wired inside and the crossover components have been renewed. Alas the crossovers are PCBs, not woodies, but I console myself with the thought that I probably wouldn't be be able to tell the difference. To me these speakers are what they're supposed to be - very neutral, which I mean in a good way, as in accurate. Paradoxically, I still think my Ditton 44s were more bassy but probably in an undesirable way. The 66s just accurately reproduce what they're given but give them an LP recorded by someone who cares about bass and boy, there are times when I hear sounds so deep and powerful my heart misses a beat because for a second I think it's an earth tremor!
I'm really enjoying my bog standard late model woodies, which are only modded to the extent they are re-wired inside and the crossover components have been renewed. Alas the crossovers are PCBs, not woodies, but I console myself with the thought that I probably wouldn't be be able to tell the difference. To me these speakers are what they're supposed to be - very neutral, which I mean in a good way, as in accurate. Paradoxically, I still think my Ditton 44s were more bassy but probably in an undesirable way. The 66s just accurately reproduce what they're given but give them an LP recorded by someone who cares about bass and boy, there are times when I hear sounds so deep and powerful my heart misses a beat because for a second I think it's an earth tremor!
No, I'm ashamed to say I had the wiring and caps changed by Wilmslow Audio, a specialist loudspeaker firm here in the UK. I only found this thread later on - pity really because it contains more than enough info for the DIYer to have a go. I don't know which replacement caps Wlmslow used but one of these days I'll get inside the cabinets and have a look. (Not much spare time currently - multiple small children.) They also replaced the clip-on connectors with soldered joints to improve signal flow.
want to try another tweeter
Alan
Have a pair of ribbon tweeters just a bit larger than the HF2000 with flat output to 35kHz. These are nominally 4 ohm and 90db SPL:
http://www.hg-audio.com.tw/ribbon-RT1102.htm
Please suggest how to adapt the crossover.
Many thanks
Alan
Have a pair of ribbon tweeters just a bit larger than the HF2000 with flat output to 35kHz. These are nominally 4 ohm and 90db SPL:
http://www.hg-audio.com.tw/ribbon-RT1102.htm
Please suggest how to adapt the crossover.
Many thanks
HF2000
HF2000 should be similar to the Coles 4001G, nominally 6 ohm and 87 db SPL:
http://www.coleselectroacoustics.com/drivece4100.shtml
Although HF2000 was available in higher impedance (= Coles 4001G nominally 16 ohm (23 ohm dc) abd 85 dB SPL) think we can rule out that model that was fitted across the HF1300 tweeter with only a blocking capacitor of 2 microF:
http://imf-electronics.com/xovers/tls80xo.pdf
The capacitor values in the Ditton66 crossover suggest that the HF2000 is the 6 ohm model.
HF2000 should be similar to the Coles 4001G, nominally 6 ohm and 87 db SPL:
http://www.coleselectroacoustics.com/drivece4100.shtml
Although HF2000 was available in higher impedance (= Coles 4001G nominally 16 ohm (23 ohm dc) abd 85 dB SPL) think we can rule out that model that was fitted across the HF1300 tweeter with only a blocking capacitor of 2 microF:
http://imf-electronics.com/xovers/tls80xo.pdf
The capacitor values in the Ditton66 crossover suggest that the HF2000 is the 6 ohm model.
tweeters for now ...
Hello all,
I have been tied up with very time consuming matters for quite a while, thus no time to continue in this thread, but I will comment on those from harnfield about the tweeters now.
I emailed to Coles months ago for some additional data for their HF2000 type tweeter, the 4001,
which harnfield posted the Link to above,
as there is not sufficient there to fully describe its response.
I have not received any reply from Coles, thus I do not feel inclined to recommend their product, but it is still common for some manufacturers to not reply to DIY type queries ...
so, as it is quite low price, and it does seem to be a close substitute for the Celestion HF2000,
if anyone wants to use them in the 66 then simply connect a 15 ohm/10watt resistor in parallel with the 7 ohm version of that Coles tweeter.
This will reduce the Impedance to match the existing cross-over components in the 66's treble filter, plus the resistor will reduce the effect of the Coles tweeter's Fs at 1.6kHz so as for it to not be misterminated by the filter.
The 15 ohm resistor must be connected across the tweeter connection terminals, so that the filter sees it as part of the tweeter.
87dB sensitivity seems to be about the correct value for the Celestion 66.
Regarding the Coles tweeter use with the HF1300. There it is also following the HF1300's cross-over filter, thus the complete filter to the Coles tweeter is the HF1300 filter plus the 2.2uF capacitor - not simply the capacitor alone.
Regarding the HG-Audio Ribbon tweeter:-
Impedance plot shows about 4.2 ohms in the region around the 5kHz crossover of the Celestion 66, thus lets keep it at 4.2 ohms, or slightly above, and use an L-Pad to reduce its 90dB Sensitivity there to 87dB.
For this, connect a 10 ohm resistor
-{wire-wound, low inductive is not necessary in this position, but minimum 5 watts - it won't get hot there - though use a higher power resistor if you prefer}-
in Parallel with the tweeter,
and a 1.2 ohm/5 watt, low-inductive wire-wound resistor in Series from the 10 ohm at the tweeter, over in Series to the 6 uF capacitor output of the treble filter of the cross-over.
This will give very close to -3dB attenuation.
See on the RT-1102 frequency response plot that its output rises from about 7.5kHz, and is about 2dB higher from 8kHz up, thus it will sound brighter in the high treble than the old Celestion tweeter.
If you do not want this extra brightness then instead of 10 ohms and 1.2 ohms, use 8.2 ohms and 1.5 ohms resistors for the L-Pad,
but do remember that this is a ribbon tweeter thus will sound a little different to a moving-coil tweeter, such as the HF2000 and Coles 4001 are.
If you want to use a new moving-coil tweeter of higher specification than the Coles, there is one suitable SEAS model which I will find the Part Number for and Post as soon as I have time to,
but do reply here if you are interested.
I hope to return to continuing with the other aspects of the Celestion 66 cross-over that I have not finished yet from earlier Posts before too long.
Hello all,
I have been tied up with very time consuming matters for quite a while, thus no time to continue in this thread, but I will comment on those from harnfield about the tweeters now.
I emailed to Coles months ago for some additional data for their HF2000 type tweeter, the 4001,
which harnfield posted the Link to above,
as there is not sufficient there to fully describe its response.
I have not received any reply from Coles, thus I do not feel inclined to recommend their product, but it is still common for some manufacturers to not reply to DIY type queries ...
so, as it is quite low price, and it does seem to be a close substitute for the Celestion HF2000,
if anyone wants to use them in the 66 then simply connect a 15 ohm/10watt resistor in parallel with the 7 ohm version of that Coles tweeter.
This will reduce the Impedance to match the existing cross-over components in the 66's treble filter, plus the resistor will reduce the effect of the Coles tweeter's Fs at 1.6kHz so as for it to not be misterminated by the filter.
The 15 ohm resistor must be connected across the tweeter connection terminals, so that the filter sees it as part of the tweeter.
87dB sensitivity seems to be about the correct value for the Celestion 66.
Regarding the Coles tweeter use with the HF1300. There it is also following the HF1300's cross-over filter, thus the complete filter to the Coles tweeter is the HF1300 filter plus the 2.2uF capacitor - not simply the capacitor alone.
Regarding the HG-Audio Ribbon tweeter:-
Impedance plot shows about 4.2 ohms in the region around the 5kHz crossover of the Celestion 66, thus lets keep it at 4.2 ohms, or slightly above, and use an L-Pad to reduce its 90dB Sensitivity there to 87dB.
For this, connect a 10 ohm resistor
-{wire-wound, low inductive is not necessary in this position, but minimum 5 watts - it won't get hot there - though use a higher power resistor if you prefer}-
in Parallel with the tweeter,
and a 1.2 ohm/5 watt, low-inductive wire-wound resistor in Series from the 10 ohm at the tweeter, over in Series to the 6 uF capacitor output of the treble filter of the cross-over.
This will give very close to -3dB attenuation.
See on the RT-1102 frequency response plot that its output rises from about 7.5kHz, and is about 2dB higher from 8kHz up, thus it will sound brighter in the high treble than the old Celestion tweeter.
If you do not want this extra brightness then instead of 10 ohms and 1.2 ohms, use 8.2 ohms and 1.5 ohms resistors for the L-Pad,
but do remember that this is a ribbon tweeter thus will sound a little different to a moving-coil tweeter, such as the HF2000 and Coles 4001 are.
If you want to use a new moving-coil tweeter of higher specification than the Coles, there is one suitable SEAS model which I will find the Part Number for and Post as soon as I have time to,
but do reply here if you are interested.
I hope to return to continuing with the other aspects of the Celestion 66 cross-over that I have not finished yet from earlier Posts before too long.
Hello everyone,
Sorry to recall an old thread
I'm interested in restoring a Celestion 66 MD-500 mid-range, which is producing a buzzing sound at certain frequencies.
Having reading this post, i saw that tonedef2 has successfully restored his MD-500 and i'm looking for more details about the procedure. I especially would like to know which part of the assembly is known to cause the buzz and what's the cure (i read that trimming something was involved ?)
jmimac, which has posted pics of his MD500 earlier on this topic was asking the same question. Jimimac, i'd like to know if you have found a way to eliminate this buzz ?
Otherwise, if it's too complicated, i also like to know if some Celestion 66 enthousiasts from Europe would do this job (remunerated, of course ;-) )
I'm interested in every kind of information related to MD-500 buzz problem so any help is welcome ;-)
regards
Sorry to recall an old thread
I'm interested in restoring a Celestion 66 MD-500 mid-range, which is producing a buzzing sound at certain frequencies.
Having reading this post, i saw that tonedef2 has successfully restored his MD-500 and i'm looking for more details about the procedure. I especially would like to know which part of the assembly is known to cause the buzz and what's the cure (i read that trimming something was involved ?)
jmimac, which has posted pics of his MD500 earlier on this topic was asking the same question. Jimimac, i'd like to know if you have found a way to eliminate this buzz ?
Otherwise, if it's too complicated, i also like to know if some Celestion 66 enthousiasts from Europe would do this job (remunerated, of course ;-) )
I'm interested in every kind of information related to MD-500 buzz problem so any help is welcome ;-)
regards
Hi picpic
1. I can't explain the cause of the buzzing problem but I do know it's very common with these units. Probably everyone will get it sooner or later.
2. If you decide not to do the repair yourself, the best person you can go to is a genius named Dave Smith who has his own company named DK Loudspeakers and works from home in Essex.
He knows everything there is to know about loudspeakers and can fix almost any unit ever made. As of a few weeks ago he was charging a very reasonable £52 per unit although of course you would have to add postage to that. He fixed my mid-ranges a few weeks ago - one was very noticeably buzzing and I thought it made sense to have both done at the same time - and now they are absolutely perfect, just a delight to listen to.
Whichever route you take, good luck!
1. I can't explain the cause of the buzzing problem but I do know it's very common with these units. Probably everyone will get it sooner or later.
2. If you decide not to do the repair yourself, the best person you can go to is a genius named Dave Smith who has his own company named DK Loudspeakers and works from home in Essex.
He knows everything there is to know about loudspeakers and can fix almost any unit ever made. As of a few weeks ago he was charging a very reasonable £52 per unit although of course you would have to add postage to that. He fixed my mid-ranges a few weeks ago - one was very noticeably buzzing and I thought it made sense to have both done at the same time - and now they are absolutely perfect, just a delight to listen to.
Whichever route you take, good luck!
Thanks for the tip
Do you know if this gentleman has an e-mail address ? I'll be highly interested to send him both of my mediums. Well, I'm looking for a intermediary person since spoken contact may be complicated - i speak french and i only found phone number to get in touch with him.
If other people in this topic are considering sending their mediums to DK Speakers, i'll be interested to put mine in it the lot !
Do you know if this gentleman has an e-mail address ? I'll be highly interested to send him both of my mediums. Well, I'm looking for a intermediary person since spoken contact may be complicated - i speak french and i only found phone number to get in touch with him.
If other people in this topic are considering sending their mediums to DK Speakers, i'll be interested to put mine in it the lot !
Well, that would be great !
I will pay him by international money transfert fto his bank account (i believe all banks accept international transferts)
If it's not possible for him, maybe I can pay you by this method, and then you can transfert him the money (and you will of course add an amount for you, i'll be glad to pay for your help, too)
So, well, I'm interested ! I will see how to send my tweeters by post to england in a couple of days and if you're still OK to help, well let's go with it ;-)
btw sorry to discuss about details in the topic, but i don't have yet the possibility to send PM's
I will pay him by international money transfert fto his bank account (i believe all banks accept international transferts)
If it's not possible for him, maybe I can pay you by this method, and then you can transfert him the money (and you will of course add an amount for you, i'll be glad to pay for your help, too)
So, well, I'm interested ! I will see how to send my tweeters by post to england in a couple of days and if you're still OK to help, well let's go with it ;-)
btw sorry to discuss about details in the topic, but i don't have yet the possibility to send PM's
I think picpic's right, you probably need to start by identifying which crossovers you have. A start would be to describe which version of the Celestion 66s you have. For example, do your speakers have teak front panels behind the grilles or particle board painted black? Are the crossovers hard wired or mounted on a PCB? Could you perhaps post photos of the crossovers?
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.