Celestion 66 needs mid-range

[kayelem]

Hi Alan,

f you would like to Post the exact mH measured values of your inductors [...]

Ditton 44 schematic and inductor measurements posted here

 

[sba]

Here's some woofer plots (at 0, 52, and 60 degrees)--









...and some THD data--



...and impedance data--




That's everything for now

 

[alan-1-b]

and the tweeter circuit ?

Hi sba,

its good you have been able to investigate further the nature of the measurements, and Post the additional, etc ...

I will reply with some ideas about the drivers and the crossover as soon as I have time available,
and after I have studied all your additional data Posts.


Do you have the JBL tweeters connected with no attenuation circuit ?

That is OK if you prefer the sound that way and it may suit the acoustics of your room,
but I would have thought it would be a bit too treble dominant with no attenuation ...... ?

I think you may have got rid of one of your HF2000s too soon, given the mismatch of the two remaining ...
which will be audible ! ...
... but if you prefer the JBLs perhaps HF2000s are no worry for you.


I'll Post about the mid-dome distortion later also.

 

[sba]

I have taken the advice of Wimslow Audio and installed a pair of MOREL CAT 298 (modified with a 94mm face plate) into my Celestion Studio 66 Monitors. At the first low volume testing they sound pretty good. Their existing tweeters installed by their previous owner were a pair of rather cheapo 'Realistc' (Radio Shack) horn super tweeters. I think the problem I have found with the various bits of information placed by other members has somehow become rather obsessed with the fact that the original HF2000's were described as 'Super-tweeters' with a frequency response from 5000Hz up-to 40000Hz. As far as I understand the adult human cannot hear frequencies much above 20kHz. The MOREL's have a range of 1.8 - 20kHz. They certainly sound much better than the previous 'Realistic' tweeters which were extremely tiring to listen to for any length of time due to the edginess at the top end. I think the real star of these speakers are the mid-range drives, which are excellent in my opinion. I'm not convinced that the passive ABR is a complete success. I have also changed the binding posts, upgrading them to a pair of high quality gold plated units. I have changed the internal wiring using 'Chord Rumour Install' wire. These are 14 AWG silver plated copped stranded cables. I understand the original cables were 18 AWG silver plated copper cables. They just seemed very thin and insubstantial. Bearing in mind that when these speakers were produced amplifiers rarely exceeded output of 70 - 80 watts. Like a lot of enthusiasts I have spent a lot of time,effort and money on the speaker wires connecting the speakers to the amplifier and it just seemed sensible to use the equivalent high quality cables inside the speakers? I would now like to upgrade the crossovers. But I must admit the prospect of doing so seems to be rather a daunting task. I have found a schematic within the pages of this extremely valuable tool (DiyAudio). I have asked Wimslow Audion to provide me with the latest equivalent high quality replacement components. I understand it will be the capacitors only which will need to be replaced? I am writing this really to obtain some feedback regarding the assumptions and methodology I am adopting. I know that these questions were first raised back as early as 2004, and have been spread over many Threads. What I would like to do is to manage to amalgamate all of the knowledge regarding the upgrading these beautiful speakers in the best possible way bearing in mind that the original drivers etc are no longer available.

Wayne,
Welcome! Its better to post in this thread, because it’s unlikely that those six-year old threads are being watched. You’re on the right track though and just need to replace the capacitors, which most likely are way out of spec. There’s info in this thread on how to do this, but at the moment I don’t have time to locate the relevant posts.

****************

Alan,
Hello! Since the JBL - Le25 is about 5db more efficient than the hf2000, I installed an Lpad in the tweeter circuit. It works well and I like having the extra HF efficiency available should a particular room need it.

I’ve also had a little time to start looking at all the data that I collected, and the thing that confounds me the most are some resonances between 2 and 2.5msec on the IR plots [I haven’t posted these yet.] . They’re apparent on all of my measurements of the LF, Mid, and HF drivers. I’m sort of curious because it makes a big difference in the FR plot whether or not these resonances are "gated" in. Once they’re included, the FR plot becomes a lot rougher. (There are some early resonances on the IR plots that do sort of make sense, such as those that are probably caused by the cabinet’s overhanging lips and grille channels, and by driver resonances. )

It’s also hard to believe that they might be room reflections, because I did my best to minimize those. The measurements were made in a large empty room with a 12‘ ceiling, with the speakers elevated, the floor dampened, and the mic placed on a suitable boom at 1.5 meters. So I really don’t know… If this stuff between 2 and 2.5ms has something to do with the cabinet, perhaps there’s a fix. Then again, it might also be some sort of hardware problem, perhaps with the mic preamp or something.

It will be a while before I can get setup again to do some testing, but, when I get a chance, I’ll post the detailed Impulse Response plots.

 

[sba]

Some IR plots of the Ditton 66 system measured at 0, 45, and 90 degrees--


0-8 millisec overview


the same, normalized


this one shows what happens to the FR when the resonance at 2 millisec is gated in


0-3 millisec close-up


the same, normalized


the same, shown with distance in cm



Any idea of what’s happening around 2 millisec / 70cm / 28 inches ?

 

[WayneSwann]

I have become aware of a pair of Celestion HF2001 tweeters up for sale. There have been some questions raised here on Diyaudio back in 2007 comparing them to the HF2000's. It would appear that the HF2001 was used in the 332, 442, 551 and 662 models,
whereas the HF2000 was used in the previous generation 25, 44 and 66 models. The question asked then was would the HF2001 work in an older 66? I was wondering if anyone has any more recent information regarding the HF2001's? By the way does anyone have or know of a pair of HF2000's going up for sale. I would really still like listen to them in the original Studio 66 setup, Even though I have gone down the replacement route! Using the MOREL CAT 298's as I previously described. Since my last posting I have given my Studio 66's with the MOREL replacements a longer and louder testing session. I must admit I am quite pleased with the results even though I realise the crossovers will need modification for the characteristics of the MOREL tweeters. I have asked Wimslow Audio to give me some idea of the cost involved in making the changes. I will attempt to carry out the work myself. I have a pretty steady hand with a soldering iron! I have spent quite some time looking at the equations involved in reaching the necessary values for the capacitors and other components within the crossover, but I must admit it leaves me with a degree of self doubt in my ability to come up with the correct values

 

[sba]

... the thing that confounds me the most are some resonances between 2 and 2.5msec on the IR plots

I narrowed the problem down to an interaction between HOLMimpulse and my sound card, an Echo Indigo I/O. Only when a soundcard calibration file is used does the caca at 2 msec appear on the IR plot. I don’t know why though… there was no problem when I tried REW (room eq wizard) using a soundcard cal.

Originally I was so focused on the FR plots that I neglected IR ones. I really wish I had magnified and examined the IRs much earlier, before making a multitude of measurements. I tried erasing the soundcard calibrations from my data files, as well as un-checking the calibration box in HOLM, but had no luck. Once the soundcard file is enabled, it seems to become an integral part of the measurements.

********************

today--

HOLM, measurement of the 66 -- caca at 2 msec still there.

.
HOLM, measurement of something different (JBL) -- caca at 2 msec still there.

.
Abandoned HOLM

.
Installed REW (room eq wizard) & made soundcard calibration.

.
REW, measurement of the 66 -- caca at 2msec not there.
http://img185.imageshack.us/img185/5976/rewb.png

.
HOLM, restarted, cleared everything, & reset default settings

.
HOLM, measurement of the 66, without soundcard calibration -- caca at 2 msec not there
http://img155.imageshack.us/img155/1361/holmwo.png

.
HOLM, made soundcard calibration
http://img710.imageshack.us/img710/3449/loop.png

.
HOLM, re-measurement of the 66, with soundcard file -- caca at 2 msec back again.
http://img294.imageshack.us/img294/1223/holmwith.png

 

[sba]

... I have spent quite some time looking at the equations involved in reaching the necessary values for the capacitors and other components within the crossover, but I must admit it leaves me with a degree of self doubt in my ability to come up with the correct values

Wayne,

Replace all of the original caps first. This will get the system closer to original spec… and protect the drivers.

If the new morel seems “bright“, then install L-pads in the tweeter circuit.

Replacement drivers should always be high quality ones that have a smooth response that needs minimal to no correction. There’s too much black magic in the 66 crossover for the home/diy user to be able to successfully alter it using various online calculators. I know this firsthand, LOL ! I put together a 12db/oct crossover for the 66 and fine-tuned it with FR measurements. It measured and sounded ok at first, but, after comparing it with the original, I had to toss it out and have a stiff drink to console me on all the hours put in. In changing the components, it’s just too easy to screw up the phase and the polar response, especially of the esteemed midrange. So if the Morel sounds good, let it ride, and enjoy the music. Moreover….you’d need acoustic measurements to see what's up with a Morel mounted in the 66.

When he returns Alan might also have some ideas on adjusting your Morel.

 

[alan-1-b]

Check this:

Hi sba,

I read in your next Post that you seem to have found the cause, or a possible cause,
for the 2 msec problem.
I do not know the idiosyncrasies of the software you are using,
however, given the distance that 2 msec corresponds to my initial suspicion is a reflection of the signal from the protruding lip at the top of the enclosure arriving at the mic.
It would be lower amplitude than the initially arriving primary signal.

If you have not suitably treated that lip with absorbent material - with one of the options I posted much earlier in this thread - then I recommend you do so and then measure again.

I apologise that I have had very little time available recently.
I hope to return and post comments and a few recommendations following your measurements soon.

 

[alan-1-b]

Briefly for now:

I have become aware of a pair of Celestion HF2001 tweeters up for sale. There have been some questions raised here on Diyaudio back in 2007 comparing them to the HF2000's. It would appear that the HF2001 was used in the 332, 442, 551 and 662 models,
whereas the HF2000 was used in the previous generation 25, 44 and 66 models. The question asked then was would the HF2001 work in an older 66? I was wondering if anyone has any more recent information regarding the HF2001's? By the way does anyone have or know of a pair of HF2000's going up for sale. I would really still like listen to them in the original Studio 66 setup, Even though I have gone down the replacement route! Using the MOREL CAT 298's as I previously described. Since my last posting I have given my Studio 66's with the MOREL replacements a longer and louder testing session. I must admit I am quite pleased with the results even though I realise the crossovers will need modification for the characteristics of the MOREL tweeters. I have asked Wimslow Audio to give me some idea of the cost involved in making the changes. I will attempt to carry out the work myself. I have a pretty steady hand with a soldering iron! I have spent quite some time looking at the equations involved in reaching the necessary values for the capacitors and other components within the crossover, but I must admit it leaves me with a degree of self doubt in my ability to come up with the correct values

Hi Wayne,

I have very little time today, thus for now:-

HF2001 is an 8 ohm spec tweeter.
It may have no better sound than HF2000, but simply different sound.

It could be adapted to work in the 66 crossover, but so can the Coles CE 4001, and that tweeter will fit the existing cut-out.

Note the unique fitting for HF2000.
I do not know if HF2001 will fit there any better than Coles CE 4001.

I'll look for data for the Morel you bought when I have time available.

Is 298 the actual Model Number of the Morel, or simply a Retailer's Catalog Number for it ?
There should be a sticker on the back of the tweeter with the Model Number printed on it.

******************************************************************

Changing the components to optimally match a different tweeter is not easy, as there are several things that need to be taken into account.
I strongly recommend that you go back to earlier in this Thread, and read through till you find my posts about crossovers and capacitors,
and then consider those.

Go also to the Thread titled:- Crossover nightmare!!!!!!!

started by:- lorienblack

which is about Celestion 44 which has the same crossover section for HF2000 as 66, and read through my posts there,
and fairly soon there will be more posted there about adapting the crossover to accomodate a different impedance tweeter.

I don't have time to post all that again.

Wimslow will sell you components, some of which you may not need because you may be able to use the existing inductor.
Also, I think the capacitors that Wimslow sell are not the optimum for that price.
Read in this thread the posts by dloper about the capacitor job he had done by Wimslow which did not provide him with the sound he wanted but knew could be achieved, and which we have been working on and will continue when he returns.

If you are not in a hurry then I recommend that you do not buy now what you may later regret, but spend the time reading through all the above, and whatever we post next about these 2 ongoing crossover adaptions.
Yes, there is a lot in both threads that is not relevant to your specific situation, but I do not remember exactly where everything is in both threads.
Unfortunately one has to search through things to find useful information.
It is time consuming - I do it myself, but hey ... sometimes I find other things there also which I did not know and which are useful
- that is part of diy !

 

[WayneSwann]

Hi Alan, thanks for your comments. You seem to be the 'Guru' in this area, your advice is very much appreciated. The MOREL CAT 298 is part of their new 'Classical Advanced (CA)' range of dome treble and mid-range units. Their spec as described in the Wilmslow Audio catalogue is as follows:-
Dia 104 mm (although they modified mine with a 94 mm faceplate so it would fit my Studios 66's).
Spl-89dB Imp-8ohm
Norm Power -80W Fs 900Hz
Freq range - 1.8 - 20kHz
£38 each.

As I have previously said I have been giving them a more extensive audition and am pleasantly pleased with the results. Although the only thing I can compare them to are the pair of 'Realistic' horn tweeters which were painfully 'Tizzy/Fizzy' and tiring to listen to. Unfortunately I have never heard them with their intended HF2000'. I maybe able to purchase a pair of Celestion Ditton 44's so therefore be able to use their HF2000's before I go ahead with any other changes. I am keeping my fingers crossed that I will be able afford them when they become available. I did a search for the Coles CE 4001 'Super-Tweeters' you mentioned. I could only find any information on the COLES own website. I have sent them an email regarding their cost and also the fact that they mention that they can alter the impedance of the speakers if required. I have never heard of this option before, so I awaiting their reply to find out what they mean exactly. I hear you regarding the possible advice offered by Wilmslow Audio, and up until now they have been the only source of any technical information for. I must admit I took their word as gospel, especially as I believe they have advised several others regarding possible replacements for the HF2000's and updating the 'Caps' in the crossover etc. I will go through the previous threads you mentioned to see what advice has been given before and to learn by others actions, be them successful or not.
Cheers
Wayne

 

[LucasAdamson]

Wayne,

I wouldn't bother with the HF2000s if I were you. I sold mine. They were good in their day, but are now very poor in comparison with modern tweeters. They are the weakest link in the 44/66s in my opinion (along with the caps of course).

I have fitted an excellent and cheap alternative in the Seas Prestige 19TFF1 19mm tweeter. Light years ahead - sweeter, cleaner, lighter and crisper. Better soundstage and better in every way to my ears. The Celestions are metallic by comparison.

Try it! You'll see...

 

[sba]

I hope to return and post comments and a few recommendations following your measurements soon.

I have some (a lot of) issues to sort out with the software, my soundcard, and its drivers. Afterward, I’ll re-measure one of the speakers and its individual drivers to get some better data.

The previous FR plots were contaminated (at 2 msec) by a very poor soundcard calibration file, which turned out to be not really a calibration at all, but a feedback loop between the “line in” and the “output”.

The problem went unnoticed for a while because I didn’t closely examine the IR plots, and didn’t even know what a proper soundcard calibration plot was supposed to look like.

The HOLM software has no documentation to help with such calibrations… hell, it even told me that I had made “valid” soundcard calibration measurements.

I would consider my earlier FR plots to be rough approximations… I suspect that the overall FR will look a bit better when it’s properly re-measured and doesn't contain the 2 msec caca.

 

[tojohndillonesq]

I have all original Ditton 66 and just spent quite a while review this MONSTER thread. My simple take aways are:

1) replacing the original caps on the Ditton 66 is a good idea because they are likely to be leaking beyond spec at this age.
2) Use poly caps
3) Match original cap values to avoid messing with the crossover frequencies
4) The cap values depend on the model and age of the speakers.
5) Lining the overhang with sound absorbing material should help the tweets
6) Putting the speakers on posts or a stand should help the bass

Corrections or Objections?

 

[LucasAdamson]

I have all original Ditton 66 and just spent quite a while review this MONSTER thread. My simple take aways are:

1) replacing the original caps on the Ditton 66 is a good idea because they are likely to be leaking beyond spec at this age.
2) Use poly caps
3) Match original cap values to avoid messing with the crossover frequencies
4) The cap values depend on the model and age of the speakers.
5) Lining the overhang with sound absorbing material should help the tweets
6) Putting the speakers on posts or a stand should help the bass

Corrections or Objections?

Good summary less this essential and crucial addendum to points 2) & 3):

Use resistors to compensate for ESR (resistance inherent to the older caps and not present in higher quality polypropylene caps you will replace with.) Alan B can advise as to correct resistors, as he has many times before.

Good reading!

 

[sba]

4) The cap values depend on the model and age of the speakers.

Corrections or Objections?

I think that the cap values remained the same throughout the production run, except for a few speakers with early serial numbers that used a 30uf (instead of 24uf cap) in the bandpass. When replacing, use a 24uf cap !

 

[tojohndillonesq]

Keeping it simple for Stupid (me)... ALL the caps should be 24uf? If so, I will start shopping...

Also, just to confuse the issue beyond all repair (FUBAR), in all this discussion I have not seen anyone ask about re-fitting the Ditton 66 to allow bi-amping. That seems like a pretty natural thing to look at if you are going to start seriously messing with the crossover... (I am NOT thinking about that myself, but I have seen all the post with replacement tweeters, need to change crossover values, etc. If you are going that far, why not bi-amp like the new speakers?)
SW

 

[sba]

You need a plan…Stan.

.

….I am dangerously willing to take apart things with no idea how to put them back together.

Before you purchase anything… lay the speaker flat on the ground, unscrew the woofer, lift it out, and place it on the ledge.

Take a long, close look at the crossover network that is mounted to the back of the enclosure. The capacitors and inductors are attached to either an older style point-to-point masonite board, or to a newer style PCB board. In either case the replacement capacitors will be much larger than the old ones, and one needs to improvise to find room for them. It’s not a simple process, like replacing a fuse. Everything will need to come out of the enclosure. Larger boards will have to be cut and mounted, the wiring needs to be redone, etc. Lots of work here...many, many hours.

I am a software guy and have a permanent injuction that forbids me from being within 50 feet of a functioning soldering iron.

Does this look like something you can tackle alone? If not...

….I do have a guy who did a very nice job rewiring my Pioneer PL-400 turntable RCA outs and power cord for me. He runs a soldering iron very artistically.

Bring him into the picture !

 

[WayneSwann]

Auditioning the Morel CAT 298 Tweerwers n Celestion Studio 66 Mointors

I have given my Celestion Studio 66's with the Morel CAT 298 tweeters installed a longer audition, especially playing CDs from my collection in which I recognise the various nuances of sound that stand out for me and which I know I like to sound in a very precise way. This is obviously years of listening to the same pieces using various combinations of equipment. As I have said the previous tweeters installed in my Studio 66's were a pair of 'Realistic' Super Tweeters purchased at 'Radio Shack'. I have done a little research regarding these Horn Tweeters and found that they were originally sold in the the 70's & 80's as 'Add On' Super Tweeters' Their model number was '40-1310B', and they have previously referred to in diyAudio. Now although their sound made the Studio 66's sound terribly bright and tiring to listen to, there were aspects of their sound I must admit I did like and which made them sound detailed in a way I had not heard before. In particular they really portrayed the sound of the High Hat Symbol in a very crisp and defined way, and dare I say, in a very realistic way. The Realistic Super Tweeters were advertised primarily as an addition to speakers to enhance the frequencies attainable by the tweeters of the day. They would be attached in parallel to the the speaker's tweeters and were placed in their own little enclosure to attain the best sound possible dependent on the room acoustics. They came with their own simple crossover and an attenuator due to the fact that they were very sensitive. They could also be installed inside the speaker enclosure with the accompanying crossovers so as to to not drown the overall sound of the speaker. In my case the tweeters were installed with no independent crossover or attenuator. So I guess that would explain the overall bright and tiring sound I was finding. It makes me wonder if they would have been OK if the required crossover/attenuators were installed? The Morel tweeters give the Studio 66' a more rounded and civilised sound but they do not reproduce the precise sound to the high hat symbol which I liked so much. Alternatively I could build my own little enclosures along with the necessary crossovers and attenuators and use the in conjunction with my Morel's? Of course I do not want to cause any overall damage to my existing crossovers but I have to bear in mind that they have been previously used with no additional crossovers in my Studio 66's for possibly many years!
As with all experimenting with separate audio equipment I also seem to create more questions than answers!. The one thing I have realised is that I do not fully understand the different characteristics of sound produced by the different type of tweeters i.e. dome, horn, ceramic, ribbon etc. If there are any characteristics which are intrinsic? Given that I am not really CAT 298 tweeters because I want them to have some of the characteristics of the sound I heard from the Realistic tweeters as well as retaining their more civilised sound.
I have been looking at the Vifa XT19TD-00-04 19mm Dual Concentric Tweeter as a replacement. The frequency range is 1 - 30kHz and they have a impedance of 4 Ohms, which is the same as the original Celestion HF2000 Super Tweeters. I wonder if anyone else has experimented using these tweeters in any of the Celestion range of speakers which used the HF2000?
As I am new to diyAudio I'm not sure how to insert links etc. into my posts but I will have a search around and and some references to other posts or external web pages.
Regards
Wayne

 

[sba]

The HF2000 output is pretty close to the other two 66 drivers.


You might try installing an Lpad, and retesting the Realistics at lower output.

L-Pad 100W Mono 1" Shaft 8 Ohm | Parts-Express.com

This solution works well in one of my 66 systems that has JBL tweeters, which are 5db louder.


You’re focusing on smaller ¾” tweeters. I prefer larger and more efficient ones, and would probably look into these-

https://www.madisound.com/store/product_info.php?products_id=1707

And, if there’s a big budget-

http://www.ciare.com/pdf/catalogo/MT320.pdf

Teleprodotti Store Vendita online altoparlanti componenti dj stage


Also, I wouldn't worry too much about what happens above 15 khz, and especially, anything above 20khz. Most of the treble energy is down below 12 khz.