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Old 17th August 2010, 11:09 PM   #511
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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
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Old 17th August 2010, 11:51 PM   #512
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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...
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Old 18th August 2010, 04:17 AM   #513
sba is offline sba
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Quote:
Originally Posted by alan-1-b View Post

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.
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Old 18th August 2010, 05:15 PM   #514
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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?
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Old 18th August 2010, 06:19 PM   #515
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Quote:
Originally Posted by tojohndillonesq View Post
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!
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Old 18th August 2010, 09:08 PM   #516
sba is offline sba
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Quote:
Originally Posted by tojohndillonesq View Post

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 !

ditton 66 network.jpg
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Old 19th August 2010, 12:12 AM   #517
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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
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Old 19th August 2010, 03:50 AM   #518
sba is offline sba
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Default You need a plan…Stan.

.
Quote:
Originally Posted by tojohndillonesq View Post
….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.


Quote:
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...

Quote:
….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 !
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Old 22nd August 2010, 12:30 PM   #519
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Default 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
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Old 24th August 2010, 05:57 AM   #520
sba is offline sba
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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/prod...oducts_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.

Last edited by sba; 24th August 2010 at 06:04 AM.
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