Celestion 66 needs mid-range

[alan-1-b]

the critical ESR simulating resistor in Midrange filter circuit

'ullo all ,

I can post only briefly today.

Yes , there has been several different resistance values tried in Series with the 3.9uF cap at the output of the midrange filter.
When I have time available I will post about the reasons why at least two different values have worked here for two different users ,
but for now I recommend that if you are using the SEAS or Hiquphon tweeters ,
then first try with 3.9 ohm in the midrange filter.

If you are using the original Celestion HF2000 tweeter , then 2.7 ohms may work better in the midrange filter ,
however try 3.9 ohms if you are not happy with the sound when 2.7 is in ,
and try 3.3 ohms if neither of the above seem ideal and if it seems somewhere in between may be better.

Do not go less than 2.7 ohms.
A 66 owner in another thread found he mistakenly had 2.2 ohms instead of 2.7
and he had reported the integration between treble and midrange to be poor.
After finding the incorrect resistance he put in 3.3 ohms , as he had a pair ,
and found the integration improved a lot.

I have read the Private Message.

I will be back when I have time available , and will get to other matters in posts on Page 106 then , I hope ...

 

[silversurfer1]

Hello again, Thanks for dropping in Alan

I got my caps and resitors last night and have had time to re-do one crossover. I did use the 2.7 ohm resistor so I will try that out and iff it needs tweeking I will tell.

I also was wondering if setting up this crossover for bi-wire is possible. To seperate the base from the upper levels? Would it take a bunch of work to sort out and would it improve anything?

Thanks agian all for your time...

 

[Qwin]

Silversurfer1 - It's easy to seperate the circuit and have individual connections, you could easily make it tri-wired if you wanted to.
If you look at Celestions own circuit diagram the circuit is in three parts for Bass/Mid/Tweeter so it is easy to follow. Instead of using common +/- inputs just make individual connections and keep the Mid/tweeter common if you wish.

Personnaly I have never found much difference with Bi wiriing. Bi amping is an altogether different thing and can be worth the expense.

 

[Qwin]

My X-Over layout

Alan – I would be very grateful if you could check over my X-Over Design click on the link to open the PDF file. I don’t want to touch the original circuit boards, so the x-overs will be all new parts. I am using HF2000 tweeters.


1). Like Silversurfer1 I intend using x2 Axon 36uf caps to make each of the 72uf values I suspect the ESR resistor values will need to change for these?

2). I have used the low Rdc Jantzen coils in the Bass section that you recommended earlier in the thread. But for the other three coils I have used Rdc values the same (Within 0.1 Ohm) as the originals. I seem to remember reading that you thought this was preferable for the mid section, but what about the Tweeter coil?

3). I have tried to keep the inductors well oriented in relation to each other and as far apart as reasonably possible. I have split the circuit on to two boards, the bass will keep the original location and the mid/tweeter board will sit behind the Mid/tweeter drivers, and will be mounted in an identical manner. Do you see any problems or areas that could be improved in the layout?

http://www.jkwynn.co.uk///Project_Images/66/66_X-Over.pdf

 

[nigel pearson]

Bi-wiring .

Bi-wiring separates the dive units . It uses the amplifier as an anchor . If offered no choice , single wire via the tweeter first is a good option . I would speculate that it is the best off all . The resistances are miniscule . The thinner the crossover wire the better in my example . Then if the amplifier output impedance plus cable is lower than the crossover a free lunch is had . The conjecture is that energy at the crossover point prefers the amplifier as a current sink . If the units have series inductor this becomes a greater reality . The inductor itself an impedance and energy store . We often hunt down distortion at - 80dB so this might just have validity . Many designers saw the mechanical path as the same problem . Roksan using damped springs to suspend the tweeter .

 

[silversurfer1]

Well hello people Happy times!!!
I rewired my crossovers with the new caps and resistors. Also put in a fuse curcuit for the tweeters and got them all hooked up last night.
Wow very happy with the outcome.... Thanks to everyone's input to this post!!!
Very pleased with the mix of Low, Mid, and Hi. Very ballanced tones and volumes.
Both Speakers very even in output. Great matching set
I used the 2.7ohm resister at the 4uf mid point and dont think the sound could be much better. Such a full 3d mix that puts you right into the music
I tested all kinds of music and very pleased with the ranges of sounds.
Im using a yamaha rx-v3800, 140w per channel. Also a pure direct mode that these speakers really shine on.
I will try to figure out how to post the pics of the re done crossovers. I put all the componets on the ditton board and it fits very well.
Looking forwards to being pulled into my music all over again.
Thanks for posting all your hard work people

 

[mixMZ]

fostex instead of MD/MF midrange

Just to add my two penn’orth
If anyone start to think how to integrate fostex driver as a mid for dittons, I would suggest SONIDO drivers (hungary DIY drivers SFR series - Fullrange drivers or SWR series - Wide range drivers) ,which sound superb! the one I heard was SFR175 on alnico magnet ,heard them in OB and was in total shock how detailed and relaxing sounding they were, since then I think that combinatios of dittons 44/66 + SWR/SFR145 could be just fantastic.

World class sounding speakers/drivers
have a look and google on those drivers.

http://www.sonido.hu/termekek.php?lang=en

 

[nigel pearson]

I have just tried an SB Acoustics driver from UK Falcon Acoustics . It is 5 inch . It seems to have considerable virtue and is a good price . From memory ( remembering errors ) a better unit than the most expensive Fostex . Flat from 100 Hz to 5 kHz . Useful between 50 Hz and 12 kHz . They look like plastic . It is a doped cloth . Something like KEF B110 married with Fostex .

 

[Qwin]

Silversufer1 - Good to hear you now have music.

What was the total value of the ESR simulating resistor you used for each of the 72uf caps (pair of Axon 36uf)? Did you use what you listed in your post #1054?

 

[silversurfer1]

Qwin, yes I used the same components listed in #1054. It was fun re doing these crossovers and I was very pleased with how they turned out.
The speakers sound great Maybe a little shy on the bass end of things. I do really like a full hard hitting base and they seem to kinda fall a little short, but really not that much.
I have two paradigm sub woofers 15" and 10" going with my system so I dont mind not pushing the speakers hard in the low end.
The output of the low end of the Dittons is very natural and responsive. When I push them they do rock and roll
With the sub woofers hitting hard the dittons are never lost. These things really have so much clean sound.
I have been reading a few other reviews of these speakers and they have been compared to many $8-10,000 dollar speakers and sounded as good or better

Thanks again for all you people that have added to this post

 

[nigel pearson]

Sorry to side track this a little . Did anyone play with Dynaco A25 ? I have a pair I would like to tune up . I suspect some reading this might have tried . Replacing the capacitor is all that comes to mind . I have added a cheap super tweeter which is working very well . Now I need to make the mid-band a bit more tidy . The grille must be a problem . What is said about the Celestions applies very well to the A25's . Classical biased speakers that can rock .

 

[jeffrey88]

Jeffery88 - I have only recently aquired 66's and have been wading through this very long thread and other sources before starting any work on my own x-overs.

There is much confusion about 66 models but as far as I have been able to uncover it goes like this:

Series Two is a compleately different design and the ABR is round the back and not on the front baffle. They really should have called this something other than 66 but were perhaps wanting to build on the 66 reputation, it is rare in comparison.

There never was an official MkI and MkII models of the 66. The product was continually updated throughout its life, but some of the changes roughly coincided with the change of the front baffle from the original Black painted (Blackies) to the later veneered baffle (woodies). Owners have started refering to the earlier versions as MkI and the later versions as mkII, not to be confused with the much later Series Two mentioned above. The boundries for changes are blurred and some blackies had some of the later features in them and some of the woodies had earlier ones probably due to cross over in stock of new/old parts. Later Woodies had PCB x-overs but some of the first of these had the older tag board x-overs. Even the tag boards varied, the very first Blackies had air cored inductors which later where wound on to plastic bobins.

Later Bass drivers had a larger dust cap but performed the same I believe.

The mid driver was originaly the MF500 which was later changed to the MD500 of identical appearance. The later mid had a higher power rating and from 50w it went to 80 watts. But the earlier mid had a flatter extended frequency response to above 6kHz and B&O used this in their 5700 model crossed over at 6k. The later MD driver barely makes the 5K crossover point used for the 66's, don't ask me which is the better sounding driver I have read claims for both. The change over point seems to have been roughly when the Woodies came on line but I could'nt swear to it.

The HF2000 tweeter fitted in the woodies with the PCB x-over were type T.2373 and had a pair of caps with a combined value of 6.2 uf in the circuit. The earlier version of the tweeter was T.1637 and used a value of 6.0 uf. In addition, there was a midrange change of capacitance in the x-over from 30uf (for MF500) to 24uf (for MD500). They used different multiples of caps from time to time to create the same total values, appart from that, the x-overs didn't change in terms of schematic from first to last production.

I hope you and others find this helpfull, I think I've got it right, please jump in if anyone knows to the contrary.

Thanks for the information Qwin.

Yes, you are right about what you've said there. I guess what I was referring to was the later production run of the original Ditton 66 vs. the first production run. I was fortunate and obtained a pair of the later production run Ditton 66 cabinets with their crossovers, bass drivers and ABRs. I'm still confused as to why when I put in my early production run crossovers with the later production run bass driver that it seemed like those bass drivers were much more sensitive, because you could very easily hear the bass driver over everything else, but putting in the early production run bass drivers resolved the problem.

And the even stranger part is the crossovers look very, very similar.

Any ideas why this is or does anyone know any specifics?

I should also report, my 66s are sounding fantastic. I'm very pleased with how they sound - really warm, cozy and smooth. I was concerned there might be problems because I bought MF500s and of course I am using my handmade crossovers from Ditton 66 parts, and using new tweeters.. but it sounds great. I think a little more tweaking could be done to get it 'perfect' but this is very good as is and I think it will be some time before I decide to go that route.

 

[Qwin]

Jeffrey88 - The Bass section is the same on all the x-over variants.

In fact the circuit design never changed throught the whole of production. There were a couple of miner changes in component values to accomodate the change from MF500 to MD500 mid range, that were introduced on the PCB type boards but the circuit was the same.

What you are hearing is probably down to the condition of the 72uf caps, these were the furthest adrift when I measured my parts. When you changed circuit boards/parts this is probably what you are hearing in the more forward sounding bass compared with the older boards/parts.

That would be my guess.

As far as I am aware the Bass drivers spec never changed, just the dust cap on very late woodies.

 

[nigel pearson]

You know what is so sad about this story , you couldn't give these speakers away in their day . I suspect it was because they had been sold in discount stores and no " reputable dealer " would touch them . I knew of one shop who rehearsed a snigger in the background if any product they didn't want to sell was mentioned . It was a stupid ploy as all it did was drive the person away form that shop . However it shows the nasty private doctor syndrome they tried to pretend to be . A doctor is qualified so might be slightly excused . Some hi fi dealers are car salesmen who think they run a Formula One team . Being generous some are justified to think they do . I met some guys I think from Griffin Radio in Birmingham . The older guys knowledge of classical music was stunning . When I mentioned Poulenc's the Gloria he said that must be the George Pretre version , he then said he had never heard it . That guy is the hi fi dealer we all should have . Doubtless like me he also listens to anything called music .

My first encounter with Ditton 44 was in Winchester . He almost begged me to buy them for £80 . I spend quite a lot of time in Winchester these days and only recently remembered being 17 ( now 58 ) and doing that . Wycham Arms is where I stay , excellent .

 

[jeffrey88]

Jeffrey88 - The Bass section is the same on all the x-over variants.

In fact the circuit design never changed throught the whole of production. There were a couple of miner changes in component values to accomodate the change from MF500 to MD500 mid range, that were introduced on the PCB type boards but the circuit was the same.

What you are hearing is probably down to the condition of the 72uf caps, these were the furthest adrift when I measured my parts. When you changed circuit boards/parts this is probably what you are hearing in the more forward sounding bass compared with the older boards/parts.

That would be my guess.

As far as I am aware the Bass drivers spec never changed, just the dust cap on very late woodies.

There must be something more to it, or something is possibly wrong with the bass drivers I have (which I have my doubts about). The crossovers I use are freshly recapped using Alcaps on the bass section, so I know it doesn't have anything to do with leaky or drifting capacitors.

That does raise something however (your post) - my crossovers use 24uF on the midrange section, should I switch to 30uF since I am using the MF500s?

 

[Qwin]

"That does raise something however (your post) - my crossovers use 24uF on the midrange section, should I switch to 30uF since I am using the MF500s?"

I would personally use 30uf with the MF500 which is what Celestion fitted.
This is the only Electrolytic in the signal path, the others all shunt to ground. I was thinking of using two Mundorf 15uf ECAP70 LL electrolytics here. The stock part is much larger than the others used on the board and may be a better quality LL item. My present thinking is to try and replace things as close to the originals as possible.

Which Alcaps did you use and what were the original Elcaps they replaced? My Elcaps are 72uf 50v NP (Non Polar) but not the LL (Low Loss) type. When replacing these Falcon Audio recomend using their ordinary 50v Alcaps and not the LL type, if you want a sound like the original Elcaps. Just wondering which you fitted?

 

[jeffrey88]

"That does raise something however (your post) - my crossovers use 24uF on the midrange section, should I switch to 30uF since I am using the MF500s?"

I would personally use 30uf with the MF500 which is what Celestion fitted.
This is the only Electrolytic in the signal path, the others all shunt to ground. I was thinking of using two Mundorf 15uf ECAP70 LL electrolytics here. The stock part is much larger than the others used on the board and may be a better quality LL item. My present thinking is to try and replace things as close to the originals as possible.

Which Alcaps did you use and what were the original Elcaps they replaced? My Elcaps are 72uf 50v NP (Non Polar) but not the LL (Low Loss) type. When replacing these Falcon Audio recomend using their ordinary 50v Alcaps and not the LL type, if you want a sound like the original Elcaps. Just wondering which you fitted?

That is what I used, 50V 72uF Alcaps (non-LL variant). I used solen 400V polypropylene capacitors for the rest (mid and treble). I have spare 6uF solen capacitors laying around, so I will put one in and see if I like it more with 30uF vs. 24uF.

 

[Qwin]

Jeffery88

Just to be sure I understand your situation - are you saying you have two sets of bass drivers, one set works well with your x-overs but the other set doesn't?

On the cap front, are you using ESR compensation with your mid range polyprop caps?

You do not need it on the Tweeter caps as the originals were low ESR film caps so you are replacing like for like more or less.

 

[jeffrey88]

Jeffery88

Just to be sure I understand your situation - are you saying you have two sets of bass drivers, one set works well with your x-overs but the other set doesn't?

On the cap front, are you using ESR compensation with your mid range polyprop caps?

You do not need it on the Tweeter caps as the originals were low ESR film caps so you are replacing like for like more or less.

Correct. I purchased a set of Celestion 66 cabinets that are of the later production run - they had the bass drivers with the larger dust caps and PCB-printed crossovers. No mids or tweeters - so I bought MF500s and used Seas 19TFF1s.

However I have lying around from my custom Celestion project a pair of the early production bass drivers with the smaller dust caps - these came from a pair of early production run Celestion 25s with the black baffle. The newer bass drivers with the dust caps are louder when I put them into my 66s, the bass was overbearing and boomy. When I put in the early production bass drivers from the Celestion 25s, everything balanced out and sounds proper.

The crossovers I have in there now were made from inductors that came from the early production run Celestion 66s, the point-to-point crossovers on the dark brown boards. I have used ESR compensation on the midrange circuit but not the tweeter circuit.

I wonder if somehow the inductors on the bass circuit are different in the PCB model - the mH value may be the same but perhaps the DCR is different - I wonder if this might be the difference? I am eventually going to try the PCB inductors on my custom crossovers and see if that solves the issue and allows me to use the newer bass drivers but wanted to get information here first before to see if someone knew the difference between the two.

 

[Qwin]

Most of the info I have come accross says the same bass driver was used in 25's 44's and 66's. The very late 66's changed to a larger dust cap but the magnet, coil assemblies were not changed and there were no x-over adjustments made for them. That's the way I think things went anyway.

Maybe the drivers with the large caps are are in some way defective like you suggested. Maybe 16 ohm? Guessing.

Part/Model numbers on the drivers? The large dust cap version should be part No T.2619 which was usually printed on one of the chassis legs.

Have you measured the resistance of the drivers and compared the two sets?

Inductor part numbers for TBC and PCC boards were the same so you would think identical.

You have probably looked at all this, it just has me stumped, same as yourself.