Quad 2905

bagkyr · « **Reply #100 on:** 19 Jan 2010, 07:39 am »

Hello,
I am to buy a pair Quad esl2905. I want to ask you if the amplifier that I have, Music Reference RM200, can him lead rightly. My space, until I move in the final space, is 4.20mX6.40mX2.8m and will be placed in side 4.20. Any indications are welcomed.
Thank you

James Tanner · « **Reply #101 on:** 21 Jan 2010, 12:41 pm »

Quote from: bagkyr on 19 Jan 2010, 07:39 am

Hello,
I am to buy a pair Quad esl2905. I want to ask you if the amplifier that I have, Music Reference RM200, can him lead rightly. My space, until I move in the final space, is 4.20mX6.40mX2.8m and will be placed in side 4.20. Any indications are welcomed.
Thank you

Hi bagkry,

i am not familiar with the sound of your amp but any quality amp with at least 100 watts at 8 ohms should be fine according to Quad. I use a 4B SST-2 on mine.

james

planaria · « **Reply #102 on:** 20 Apr 2010, 07:17 pm »

Another pair of 2905's, another update.

Replaced the step-up transformers with Plitron 75:1. Following Hap's and Niels' advice, I tried Duelund resistors instead of Mills - interesting. Duelund seemed to show more detail, but a shift in tonality towards the bass. Altogether a pleasing effect, but a trade-off.

Next tried nichrome wire, and found yet more clarity, and no tonality shift. This will be my reference, if it still seems good after extended listening - but the speakers are now exceedingly revealing, now showing clear differences between premium brands of small signal resistors in the amp (nude Vishays vs Caddock Mk132's).

A final note on fit and finish. The newer 2905's seem to be better made than my example from 3 years ago, and those appeared better than 2805's from the same period. This was manifested by superior attention to strut mounting - the latest 2905's were fine right out of the box.

harry_at · « **Reply #103 on:** 10 May 2010, 05:21 pm »

Quote from: planaria on 20 Apr 2010, 07:17 pm

Another pair of 2905's, another update.

Replaced the step-up transformers with Plitron 75:1.

Hi Planaria,

are you using two 1:75 Plitron transformers per speaker (primaries parallel and secondaries in series)?

Will have to look if the Vanderveen designed transformers are also available here in Europe for my Esl-63.

Regards,

Harry

planaria · « **Reply #104 on:** 10 May 2010, 10:39 pm »

Hello Harry.

I used one transformer per speaker. Since the Plitrons are centre-tapped, one can use the positive and negative sides to drive the stators directly in a well balanced push-pull configuration. Since this connection involves removing some of the protection circuitry, I would only use low power, high stability amplifiers.

I understand that the 2905's and ESL63's use mostly identical parts, so these Plitrons should work equally well in 63's.

harry_at · « **Reply #105 on:** 11 May 2010, 09:02 am »

Quote from: planaria on 10 May 2010, 10:39 pm

I used one transformer per speaker.

but how is then possible to get along with such a low turns ratio?

Don't know the exact specs of the 2905, but the Esl-63 has two single ended 1:122 transformers per speaker. You mentioned in an earlier post that volume suffers, but the 1:75 turns ratio is "miles away" from the original. I'm puzzled about this difference.

I can refurbish the panels of my Esl-63 (have a stretching jig and oven) - used a thinner foil and coating. Always searching for good upgrades. So I like your transformer mod. On my list are also the ceramic caps in the delay line. I think that Quad has not upgraded them to foil types in the 2905.

Thanks for your reply,

Harry

planaria · « **Reply #106 on:** 11 May 2010, 05:34 pm »

Hello Harry.

1:122 and 1:75 are somewhat different, but not miles apart. Only about 6dB, in fact. Any pre-amp should be able to accommodate that.

I agree about the delay line caps - I have been thinking along the same lines - but 5KV film and foil are hard to come by. I plan to make my own with copper disks and dielectric film, but haven't got around to it.

Terry

harry_at · « **Reply #107 on:** 12 May 2010, 09:58 am »

Hi Terry,

with 'miles away' I was pointing at the two 1:122 transformers which are wired in a parallel/series
connection. This gives a step-up ratio of 1:244. Taking this into account, Quad did a very good job with such a complex design.

For comparison, in the Esl-57 the bass section has a ratio of 1:290 and the treble 1:90.

Regarding the delay line caps. In the Esl-63 are 6kV/AC ones. I'm also trying to go the DIY route with caps made of teflon foil and copper in a stacked plate design.

My plan is to use a square piece of copper with a tab, then a larger teflon piece, then some drops of wax between heated with a iron and so on (the wax should also eliminate trapped air between the sheets). Maybe Polyurethane is an alternative to wax. And sealing this pack with Epoxy. I have bought some copper foil. But I will order a thinner one because it is too thick. What I'm not so sure about is the required dielectric thickness. What I have found is that 0,001 inch teflon should handle 1 kV/DC (measured at 1 MHz). For AC twice the thickness and adding 50% safety margin gives 0,018 inch for 6kV...

Harry

planaria · « **Reply #108 on:** 12 May 2010, 05:49 pm »

Hello Harry.

Even 10dB is within the scope of most preamps - only 5 "just-noticeable-differences". Further, empirically, it works in my system.

I think that a lot of problems go away with rigid disks of conductor, problems such as air bubbles and non-constant inter-conductor distances. As for stacking, that should not be necessary because the required capacitance is only about 20pF. Our biggest problem is going to be the dielectric, because any pin-hole problem is going to be serious at these voltages.

That being said, I doubt if the speaker will ever see 15VAC from my amplifier, and multiplying by 75 only gives 1KV - not excessive. But a safety factor is essential. "Most data apply to relatively thin sections and cannot be multiplied directly to give breakdown voltage for thicker sections without added safety factor." (Notation in radio amateur's handbook)

harry_at · « **Reply #109 on:** 12 May 2010, 06:15 pm »

Quote from: planaria on 12 May 2010, 05:49 pm

As for stacking, that should not be necessary because the required capacitance is only about 20pF. Our biggest problem is going to be the dielectric, because any pin-hole problem is going to be serious at these voltages.

Yes. Better to use multiple sheets than a bulk foil. Also with 22pF stacking seems to be necessary. I have calculated a bit and with 0,018 inch or more spacing, the cap gets quite large.

Harry

tbald53892 · « **Reply #110 on:** 17 May 2011, 07:46 pm »

I recently acquired a pair of the 2905s. What an great speaker...detailed, revealing, and with an amazing "startle" factor. Now I'm wondering how one gains access to the 2905 power module for modifications? Must the back brace be unscrewed from the base before the plinth cover can be removed? I just want to make sure I know all the "tricks" before attempting to gain access to the power module. I realize its safety first when working with ESLs and the necessary high voltages. Any suggestions would be most helpful and welcome. Thanks!

planaria · « **Reply #111 on:** 29 May 2011, 07:57 pm »

Hello TBald.

Yes, that's right, the strut must be removed. Glad to see that you are mindful of the risks of high voltage - there are a few suggestions in previous posts. Good luck!

katamapah · « **Reply #112 on:** 3 Aug 2011, 10:21 pm »

Hi,

I found this thread occasionally on the internet and read it with a lot of interest.
I would like to ask how newer versions of QUAD ESL with additional
bass panels perform in other styles of music rather traditional QUAD ESL
ultimate - jazz, classic, vocals and acoustic in general. Are they a way better then ESL63 let's say in progressive rock, pop of 80's psychedelic, fusion, or modern free jazz with some touch of electronic ?
I am not talking about hard rock, trance/house/excessive electronic or dynamic music.

Unfortunately, I can't listen to the new QUADS ESL in my area, so all i can do is trust some reviews and ask for people opinions.

I liked a lot ESL63 for what they do, but they were almost unlistenable while I was feeding them with LED ZEPPELIN or BoneyM for example.
So how are the new ones ?
Thank you.

planaria · « **Reply #113 on:** 7 Aug 2011, 04:01 am »

Hello Kata.

I have never owned ESL63's, but used ESL57's for years. (Still have two pairs.) So no direct experience - treat my reply accordingly.

I understand that the ESL63's are very similar to the latest 2x05's. The main differences are build quality and rigidity - newer being better. I found my unmodified 2805's to be punishing with a digital source - any music at all - but worse with recordings which used distortion as a design element. After modification this improved, but vinyl was still far superior.

To my ears, the unmodified 2905's seemed more forgiving of digital distortion, but still too revealing for comfortable listening. After modification this effect diminished - it was as if some edge detectors had been removed - as indeed, an electrolytic cap had been removed. My solution is to put a 13KHz filter (6 dB per octave) between the player and the amp. Since I built my own pre-amp, this was easy, and very worthwhile.

A very much cheaper solution for digititis is to stack several ESL57's. I find my stacked ESL57's just as musical and satisfying as the modified 2x05's - but lacking the high and low octaves, and some mid-range clarity. Stacked 57's offer very good value for the money, and they pair quite well with the B3-SST Brystons (I would guess the newer Brystons are even better), which are bullet-proof.

Stacked ESL57's, with all their limitations, are more musical to my ears than any other brands I have heard, including Magnepans and Martin Logan hybrids, which I also own.

My suggestion: for analog, modified 2905's. For digital, modified 2905's plus a filter, or stacked ESL57's.

Hope this helps - but remember, just one geek's opinion.

katamapah · « **Reply #114 on:** 7 Aug 2011, 10:41 am »

Hi,
Thanks for the answer.

From yesterday, i think of much simpler route: may be just buy an additional pair of OK dynamic speakers ?
They should be fine for most modern electronic and rock experience. They will have better slam and i guess for nice
rock experience there is no need for ultimate speakers. For more "intimate" and acoustic type of music, vocals and some classic - where you really
need a very emotional speaker - ESL will continue to do the job.
Beside of inconvenience of having two pair of speakers, it might be the best and cheapest way to get what i want.
The second pair of speakers might also be a good backup for QUADs...

Another option, is to sell the QUADS and go for some "ultimate" speaker on the second hand market.
Something like Sonus Faber Extrema (or other SF models), or Willson Audio.
It will be a much pricey solution though...
Not just because of the speakers, but also because of all the amplification chain...
Currently i use a moderate-powered tube amplifier with ESL63 and it sounds very emotional at what it does well...
My room is also small (about 15 sq. m or 50 sq. feet) - not suit very well for really big dynamic speakers out there.
This is also the reason i am not sure i can go the stacked QUAD route... small room....

planaria · « **Reply #115 on:** 7 Aug 2011, 06:59 pm »

Hello Kata.

I think that I am beginning to understand your question better. I would NOT sell my ESL63's. I would either upgrade the Quads or buy some other speakers especially for rock. The latter would have the advantage that you could play them LOUD, which you could never do with the Quads. On the other hand, upgrading your ESL63's would improve all your listening.

I would NOT buy other speakers to replace the Quads, because all manufacturers build to a price point. That means that almost all manufacturers use electrolytic caps in their speakers, and it makes the speakers sound shrill, edgy, and unpleasant. It's just that the Quad ESL's are so revealing that you can hear just how bad that electrolytic cap really is. Other speakers are not more refined, they are less transparent, and have less potential.

If you want to upgrade, there are two possibilities:
1) upgrade the caps and resistors between the RCA connector and the step-up transformers; or
2) upgrade the step-up transformers to Plitron 75:1 and tune the transformers with Duelund resistors.

These two strategies are discussed above, and in a similar thread on Audiogon. Cost should be about $1500. All the best!

Marius · « **Reply #116 on:** 8 Aug 2011, 09:08 am »

Hi,

Playing ESL63 for as long as they exist....playing loud too , in a rather large auditorium.
using 28b's without a problem, on the contrary, ringing like a bell, never sounded better.

Rock, classical, jazz whatever. The Orks from LOTR really make a stampede....

Only thing I had to do was add a subwoofer (2 might even be better) , and use the 10bsub to divert the lower frequencies to the sub instead of to the ESL's, which thus can play freer, and louder for that matter.
After having tried a lot of subs, decided to go with the REL B1. Merges beautifully ! Settings that work best in my place is to crossover at 100hz.
Just my 2 cents.

(also tried the 2905's but sent them back again. ESl63/sub-combo really sound more musical. Highs and high-mids far too obtrusive for my taste. Design far too obtrusive for my wife's...2905's better made though apparently )

Greetings,
Marius

planaria · « **Reply #117 on:** 8 Aug 2011, 04:49 pm »

Hello Marius.

Thanks for clarifying the volume issue - I guess you can play them loud if you don't use the bass panels. I agree about the Brystons, but not about the sub. Everything I have ever tried sounds flabby compared to the Quads - but the quest continues.

katamapah · « **Reply #118 on:** 12 Aug 2011, 10:38 pm »

Hi, haven't been here for a while...
Busy at work...

I read some reviews and i will try to listen to Magnepan 3.7 and Martin Logans.
They presented here by the same dealer.
That's for a moment. Also trying to negotiate with Quad dealer a 2905/989 presentation. It's a pitty they don't have one on display, but they said not many ppl buying this speakers today, so it is not economically wise for them to have one on display. From time to time there are certain trade-ins and then its the time they can offer a presentation. Should call me back with info as for whenever there is one now... I guess most of all he wants to be sure i am seriously about buying one. But i can't really tell till i listen...

Anyway, i will continue and update here from time to time as for my findings.
It is very helpful to share an opinion with other people. It is difficult to buy something, based solely on other ppl opinions though...
Thanks.

BruceSB · « **Reply #119 on:** 13 Aug 2011, 02:21 am »

Full range electrostatics have their own particular sound.
You really do need to hear them to be sure that you like that particular sound.
The first electrostatics that I heard were the Quad 63s and that was love at first hear!
I also heard and loved the Martin Logan CLS but I bought Acoustat spectra 22s!
Since then I have heard lots of other full range stats, including the later Quads, and yes, they also sound great.
Right now I am wondering about SoundLabs or Audiostatics.
Yes, full range electrostatics do sound a little different from each other, but then there are also other matters such as room size, how much base you require, whether you like them tall & skinny, tall and wide, or short and wide, not to mention WAF!
However, I just can't stress enough that if you are interested in full range electrostatics you do need to hear them!
I could say that the Quads are a great speaker but you know that I am biased!
Hope that helps.
Good luck on your quest.