Celestion 66 needs mid-range

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I'll send another mail to british celestion and beg for schematics and wait. If i get response, I'll share details.
Sb.
Hi Sb,

You could also try contacting the service department at www.kef.com.

About four years ago I requested technical details for two speakers in the SL range from the celestion.com site and they kindly sent the request to the kef service department and the Service Dept Administrator kindly sent me the details in a return email. The information is probably available for speakers they service so the 332 etc may be before they took over.
 
Celestion and KEF , and Ditton 332 HF2001 tweeter Polarity

Hi Denny G , and starbender ,

Celestion and KEF are now both owned by Gold Peak Industries ,
which is an Asian company listed in Hong Kong , and also has an office in Singapore.
Most , but not all , of their loudspeakers - drivers and cabinets and assembly is currently done in China.
I doubt they would be doing an servicing of very old models like Ditton 332 and 442 ,
but perhaps they can access whatever database that hopefully contains the schematics for the crossovers if such is on-file anywhere.


starbender ,

I have now posted in your old "Celestion Ditton 332 Crossover" thread in this Forum how to identify the Polarity of the Ditton 332 HF2001 tweeter.
 
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Listening experiences

Hi ToTo Man ,

About your statements:
---
"It really is quite remarkable what an audible difference this has made to the perceived ‘clarity’ and ‘speed’ of the presentation. The differences become even more audible and measurable at farfield distance:
[ image ]

I therefore went ahead and reversed the polarity of the other woofer and have been living with the speakers as an ‘inverted LF’ pair for just over a week now and it has been nothing short of a revelation. One downside I‘ve noticed is, subjectively, the change in vertical off-axis response has become more marked (e.g. when you stand up and walk towards the speaker the LF/MF balance changes more dramatically than before and the effect can be a little odd). However, when listening in the sweet spot, the presentation ‘locks’ into place and is eerily realistic."
---

I reply:

Your descriptions of the sound has reminded me of:

1)- listening to a 3-way loudspeaker a little over 10 years ago which had its Woofer and Tweeter in reverse polarity and small Mid-cone in positive polarity ...
... and that was how it was designed to be with its particular crossover -{ which was all Third-order to all drivers if I was correctly informed }.

I remember it distinctly because a neighbour was thinking of having one made -{ it was a Custom design and manufacture }-
thus we listened extensively to the prototype , and I was particularly impressed by the small Mid-cone as it covered the Female vocal range very well.
The effect of positive polarity mid-range with reverse polarity on my type of brain/hearing is highlighting of midrange presentation , and with Bass and Treble laid-back in image behind the Mids ,
and that I expect listeners to favour for listening to their favorite vocalists when they want the accompaniment music -{ full Orchestral accompaniment was the music we listened to }- placed behind the singer.
However for my type of brain/hearing what I didn't like was the loss of Presence of the Orchestral parts , and the loss of Impact at dramatic occasions in the songs.
I also own a copy of the recording that my neighbour used that day , and I can hear everything he liked about it through my preferred loudspeakers , and also the additional things I like to hear ,
however my point remains as I stated previously about Polarity ,
and that is the different listeners have different brain/hearing priority interpretations.

2)- With a 2-way loudspeaker that I own which has Tweeter connected in Reverse polarity to the bass/mid driver ,
I hear a lot of Clarity in the Stereo Image - particularly in the Depth of the image - when listening at low volume ,
but when I tun the volume up much of the Imagery collapses into muddle and Impact is lost.

The: "locks’ into place and is eerily realistic" - that you mention was there when I listened at low volume levels but not when I listened at high volume levels
-{ I did not listen at extremely high volume but only at louder than spoken conversation level }.

Phase differences in music and speech listening do present Eerie effects , dependent on the degree of phase shift of whichever part of the audio spectrum is shifted with respect to the remainder of the audio spectrum ,
and that gets used a lot when Mixing multitrack recordings to prepare Masters for some types of Pop and Rock music styles.

The " LF/MF balance " that you hear changing when you listen on different Vertical Axis at different distances is result of the relative phase changes interacting differently when the then arrival times of the signal from each driver is changed.

--- --- ---

" Looking back at the individual circuit responses in #1214 I wonder if Celestion should have moved the LF roll-off earlier than 500Hz whilst keeping the MF roll-off at 500-600Hz, to intentionally create a dip in the response and reduce the ‘warmth’ / ‘bloat’ that is audible at these frequencies? When wired as standard, my ears tell me the woofer is not rolling off early enough. I guess that rolling the woofer off earlier (or adding a filter to the crossover to reduce its output from 300-500Hz) would likely have created more problems than it solved?! "
-

My reply is:
I do not know the Listening Axis nor listening Distance that Celestion may have optimized 66 for ,
but as it is a Large loudspeaker it was most likely optimized for listening distances of more than 6 feet ,
and probably for about 10 to 12 feet -{ 3 to 4 metres }- in large listening rooms ,
albeit Home listening rooms not Auditoriums.

{ Ignore the "Studio Monitor" appellation as that has different meaning dependent on type of Studio and type of Music Style ,
Example: for the very small BBC Monitor LS3/5A it was designed primarily for spoken voice monitoring is small radio broadcast studios where near-field was the only pragmatic listening position.}

What you hear in your preferred listening position in your size room may be different to Celestion's primary intention ,
{ and also your brain/hearing interpretation may be different to that of Celestion's primary Designer then ... and Celestion have had different designers for different models }.

Rolling the Woofer off earlier may cause the sound to be too thin in some locations , and as those mid-domes cannot be used to lower frequencies whatever lower mids required had to be got from the woofer.

Also , I have found that some of low mids bloating can be reduced by using polypropylene capacitors plus small resistance resistors instead of electro caps or instead of poly caps with no resistors ,
but some listeners do not like that sound.

With the crossover connected as you now have it the lowest Octave from the mid-domes are part cancelling the low midrange from the woofer output
- only part cancelling because the mid-dome are being rolled off by the crossover in that Octave.

After you have decided whether you prefer 24uF or 30uF to mid-domes you can try small resistance in Series with the woofer circuit output capacitor to change the slope of the low-mids roll-off ,
but the electro-cap will always cause some bloating as result of its Dielectric Absorption which polypropylene capacitors do not have to anywhere near such degree of.

Also , as you seem to have found your different vintages of cabinets cause different low mids sounds ,
you should decide your preferred cabinet before you attempt more tuning of the low-midrange in the crossover.

Next I advise moving the crossover away from the back of the Woofer because the magnetic field from the woofer's large magnet is interacting with the magnetic fields around the crossover inductors and that is causing bloating or similar in most areas of the frequency spectrum.
-{ and which also you having reversed woofer polarity is now part cancelling part of the Sum of the magnetic fields' interactions but they are still present and now changing the sound differently }.
Celestion did not put the crossover board where it is for any Audio reason - they put it there for the simplicity and lower cost of assembly for the loudspeaker.
Reduction of Costs is always imposed on Designers by the Financial Managers of companies ,
and those Managers usually argue that most listeners will not hear the difference , and that some who do will not care ...
... sorry , but the General Public are always condescended to by finances' allocators as the only sound they really care about is the sound of Profits.
 
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Hi Denny G , and starbender ,

Celestion and KEF are now both owned by Gold Peak Industries ,
which is an Asian company listed in Hong Kong , and also has an office in Singapore.
Most , but not all , of their loudspeakers - drivers and cabinets and assembly is currently done in China.
I doubt they would be doing an servicing of very old models like Ditton 332 and 442 ,
but perhaps they can access whatever database that hopefully contains the schematics for the crossovers if such is on-file anywhere.


starbender ,

I have now posted in your old "Celestion Ditton 332 Crossover" thread in this Forum how to identify the Polarity of the Ditton 332 HF2001 tweeter.

Thanks Alan.

I sent an e-mail to KEF and beg for schematics or any info. One week passed, no reply yet.

As for HF2001's; There is no mark at all on tweeters. But I do short battery check and marked polarity.
 
Celestion 332

Hi Starbender ,

I have posted some comments after your Schematic post in your Celestion 332 thread.

Also , there is a Red mark spot visible in that Photo of that Tweeter you posted in #32 in your Celestion 332 thread.
The Red spot indicates the Positive connection side , and that should be the same as you found with the battery test that you did.
 
Repairer of MD and MF mid-domes

Hi ToTo Man , and whoever else has faulty MF or MD domes.

Go to Posts numbers: 187 to 194 on Pages 19 and 20 in this Thread and read what jmimac showed in photos and explained about repairing.

If you are not confident to try that repair yourself , then send a Private Message through this Forum to jmimac and ask if he will do the repair for you.
 
md500 restore

Here is how I got the speaker with the dome unglued.

I now have a new coil for one of my 500's. To get the old one out, the *bakelite* seemed to be glued to the aluminum disk, and the cork gaskets on each side of the coil were glued. the new coil came with *paper* gaskets.

Question: do all these components get reglued, & if so, with what type of adhesive?
 

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Hi ToTo Man ,

About your statements:
---
"It really is quite remarkable what an audible difference this has made to the perceived ‘clarity’ and ‘speed’ of the presentation. The differences become even more audible and measurable at farfield distance:
[ image ]

I therefore went ahead and reversed the polarity of the other woofer and have been living with the speakers as an ‘inverted LF’ pair for just over a week now and it has been nothing short of a revelation. One downside I‘ve noticed is, subjectively, the change in vertical off-axis response has become more marked (e.g. when you stand up and walk towards the speaker the LF/MF balance changes more dramatically than before and the effect can be a little odd). However, when listening in the sweet spot, the presentation ‘locks’ into place and is eerily realistic."
---

I reply:

Your descriptions of the sound has reminded me of:

1)- listening to a 3-way loudspeaker a little over 10 years ago which had its Woofer and Tweeter in reverse polarity and small Mid-cone in positive polarity ...
... and that was how it was designed to be with its particular crossover -{ which was all Third-order to all drivers if I was correctly informed }.

I remember it distinctly because a neighbour was thinking of having one made -{ it was a Custom design and manufacture }-
thus we listened extensively to the prototype , and I was particularly impressed by the small Mid-cone as it covered the Female vocal range very well.
The effect of positive polarity mid-range with reverse polarity on my type of brain/hearing is highlighting of midrange presentation , and with Bass and Treble laid-back in image behind the Mids ,
and that I expect listeners to favour for listening to their favorite vocalists when they want the accompaniment music -{ full Orchestral accompaniment was the music we listened to }- placed behind the singer.
However for my type of brain/hearing what I didn't like was the loss of Presence of the Orchestral parts , and the loss of Impact at dramatic occasions in the songs.
I also own a copy of the recording that my neighbour used that day , and I can hear everything he liked about it through my preferred loudspeakers , and also the additional things I like to hear ,
however my point remains as I stated previously about Polarity ,
and that is the different listeners have different brain/hearing priority interpretations.

2)- With a 2-way loudspeaker that I own which has Tweeter connected in Reverse polarity to the bass/mid driver ,
I hear a lot of Clarity in the Stereo Image - particularly in the Depth of the image - when listening at low volume ,
but when I tun the volume up much of the Imagery collapses into muddle and Impact is lost.

The: "locks’ into place and is eerily realistic" - that you mention was there when I listened at low volume levels but not when I listened at high volume levels
-{ I did not listen at extremely high volume but only at louder than spoken conversation level }.

Phase differences in music and speech listening do present Eerie effects , dependent on the degree of phase shift of whichever part of the audio spectrum is shifted with respect to the remainder of the audio spectrum ,
and that gets used a lot when Mixing multitrack recordings to prepare Masters for some types of Pop and Rock music styles.

The " LF/MF balance " that you hear changing when you listen on different Vertical Axis at different distances is result of the relative phase changes interacting differently when the then arrival times of the signal from each driver is changed.

--- --- ---

" Looking back at the individual circuit responses in #1214 I wonder if Celestion should have moved the LF roll-off earlier than 500Hz whilst keeping the MF roll-off at 500-600Hz, to intentionally create a dip in the response and reduce the ‘warmth’ / ‘bloat’ that is audible at these frequencies? When wired as standard, my ears tell me the woofer is not rolling off early enough. I guess that rolling the woofer off earlier (or adding a filter to the crossover to reduce its output from 300-500Hz) would likely have created more problems than it solved?! "
-

My reply is:
I do not know the Listening Axis nor listening Distance that Celestion may have optimized 66 for ,
but as it is a Large loudspeaker it was most likely optimized for listening distances of more than 6 feet ,
and probably for about 10 to 12 feet -{ 3 to 4 metres }- in large listening rooms ,
albeit Home listening rooms not Auditoriums.

{ Ignore the "Studio Monitor" appellation as that has different meaning dependent on type of Studio and type of Music Style ,
Example: for the very small BBC Monitor LS3/5A it was designed primarily for spoken voice monitoring is small radio broadcast studios where near-field was the only pragmatic listening position.}

What you hear in your preferred listening position in your size room may be different to Celestion's primary intention ,
{ and also your brain/hearing interpretation may be different to that of Celestion's primary Designer then ... and Celestion have had different designers for different models }.

Rolling the Woofer off earlier may cause the sound to be too thin in some locations , and as those mid-domes cannot be used to lower frequencies whatever lower mids required had to be got from the woofer.

Also , I have found that some of low mids bloating can be reduced by using polypropylene capacitors plus small resistance resistors instead of electro caps or instead of poly caps with no resistors ,
but some listeners do not like that sound.

With the crossover connected as you now have it the lowest Octave from the mid-domes are part cancelling the low midrange from the woofer output
- only part cancelling because the mid-dome are being rolled off by the crossover in that Octave.

After you have decided whether you prefer 24uF or 30uF to mid-domes you can try small resistance in Series with the woofer circuit output capacitor to change the slope of the low-mids roll-off ,
but the electro-cap will always cause some bloating as result of its Dielectric Absorption which polypropylene capacitors do not have to anywhere near such degree of.

Also , as you seem to have found your different vintages of cabinets cause different low mids sounds ,
you should decide your preferred cabinet before you attempt more tuning of the low-midrange in the crossover.

Next I advise moving the crossover away from the back of the Woofer because the magnetic field from the woofer's large magnet is interacting with the magnetic fields around the crossover inductors and that is causing bloating or similar in most areas of the frequency spectrum.
-{ and which also you having reversed woofer polarity is now part cancelling part of the Sum of the magnetic fields' interactions but they are still present and now changing the sound differently }.
Celestion did not put the crossover board where it is for any Audio reason - they put it there for the simplicity and lower cost of assembly for the loudspeaker.
Reduction of Costs is always imposed on Designers by the Financial Managers of companies ,
and those Managers usually argue that most listeners will not hear the difference , and that some who do will not care ...
... sorry , but the General Public are always condescended to by finances' allocators as the only sound they really care about is the sound of Profits.

Hi ToTo Man , and whoever else has faulty MF or MD domes.

Go to Posts numbers: 187 to 194 on Pages 19 and 20 in this Thread and read what jmimac showed in photos and explained about repairing.

If you are not confident to try that repair yourself , then send a Private Message through this Forum to jmimac and ask if he will do the repair for you.

Thank you Alan, I will bear the above in mind in my future 66 experimentations. So far I have not altered anything since my last post as I am simply enjoying the sound too much. It has been a long time since I have been this contented with the sound of my system! :)
 
Amocom reply

Hello all ,


"Hi Doug ,



I do not recommend those new crossovers for Celestion 44 and 66.

They look like they will work , and would give better sound than old crossovers with deteriorated capacitors ,
but the capacitor choices can be bettered ... unless a listener particularly like those capacitor combinations.

Primarily, the Inductors do not need to be replaced , as there is nothing substantially wrong with the original Celestion inductors.
If one wants the small benefits of modern manufacturing then better when changing the Inductors would be to use larger air-core inductors in the woofer circuit and first in midrange shunt circuit ,
because using Cored inductors introduces Saturation ... if you like the compression effects of saturated inductors OK your choice ,
but ... and I have posted plenty about that previously in this thread."

As the producer of these crossovers here at AMOCOM I would like to respond

Both the 44 and 66 models emulate the original Celestion design EXACTLY.
The ALCAP capacitors are employed as they provide the same ESR (Equivalent Series Resistance) of the original ELCAPS and PYE caps exactly (almost). ESR is vital to ensure the relative balance between Hi, Mid and Lo filters is retained. Film capacitors (agreed, they are better quality) disrupt this balance and the results are poor.
All inductors on the 66 model are air cored.
2 of 5 inductors on the 44 model are air cored, again as the original design.
My aim when producing these replacements was a simple plug and play option to emulate the original factory sound as closely as possible. Recycling the existing inductors was an option but proved to be unpopular and is now withdrawn.
All reviews, submitted by my clients, have been very appreciative and praising of the results. Not a single negative or dislike amongst them.
Thanks for taking time to comment and I hope this has explained why these new crossovers retain their popularity.
Best wishes to all, Tony Morris
 
KEF 105.1 crossover adventure

Hi Alan and all,

intriguing thread, thanks so much for so much wisdom.

I am recapping the crossovers (schematics below) of a pair of KEF reference 105.1. I have used the Falcon kit for this, which supplies two polyester caps (C10) which are not there in the original crossover (only Elcaps plus one polyester tropical fish, C11).

The speakers sounded more interesting, but I quickly disliked the balance. So then the swapping started, until I ended by re-inserting a bipolar (Mundorf Ecap smooth for C10). I also changed C5 at the input of the mid section to a Mundorf ECap smooth (just fits). I put a WIMA MKP4 instead of the tropical fish (C11).

After reading in this thread I now understand much more about ESR and ESR-simulating resistors. I am fine with the sound now, but I wonder if I can further enhance sound quality by replacing Alcaps with polypropylene where this does no harm (presumably C6 and the Zobels). Or will this be insignificant?

What are your opinions on that? Anyway I'll change C7 (Alcap 50V) to a Mundorf raw 100VDC as the Mundorfs, even raw, seem to be of a slightly higher quality. A smooth one won't fit here.

Space is very much limited on the crossover, as it is in the back of the "heads" of the speakers, and I want to keep everything looking as much as originally as possible. I probably could add small ESR-simulating resistors to eventual polypropylenes in the tweeter section, but this might be still to messy for my liking.

I am wondering why Falcon put in a polyester at a place where it clearly changes the sound to the worse (albeit more spectacular).

Thanks!

*The schematics is here:
http://techtalk.parts-express.com/filedata/fetch?id=1161363&d=1555597338
 

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If you can measure the old alcaps, you can determine the correct amount of ESR to add to the newer polyprops. It is important to add ESR resistors, as otherwise the whole balance can be thrown off, and any etherial and subtle improvement of the cap "quality" will be dwarfed by incorrect values in the design.
 
Hi Lucas, thanks.

Did you mean measure the Alcaps which Falcon supplied? And then calculate the ESR-simulating resistor from that?

The original Elcaps probably have drifted too far to make it meaningful to measure them.

How would you measure ESR? I've got a DMM and a scope. Probably Alan has covered it somewhere in this thread.
 
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