Converting 11a (6550) to 11XS (EL34)

[ks9sunset]

Currently using 11a with 6550 tubes on Omega Super Alnico Monitor of 92db in a 16'x14'x8' room, wonder if it is worthy to convert the 11a to 11XS using EL34 tubes; would that be much benefit or improvement in female vocal such as Diana Krall, Stacey Kent and Norah Jones etc.?

[Big Dog RJ]

G'day mate,

Yes, the XS EL34 version will be a much sweeter, and more detailed sound. However, the amplifier will lose half it's power output, hence from 70w it will drop to around 35w/ch.

All depends on the efficiency of your speakers, room dimensions and your listening habits. Also depending on the listening position distance, if you prefer near-field or further away, over 9ft and want to fill the room, all need to be considered.

I remember when we ordered in the first XS version fitted with EL34's driving Quad ESL63's, it was marvellous! That soundstage depth and 3D imaging was what hit me, and since then I just stuck with panels as part of my main reference systems. Then I remember we connected the Prem11A to drive Maggie's MG3.5/r full range. This time not aided by subs and separate bass amplifiers like we did on the Quads, however the Prem11A was stressed out. Ordered in another version with 6550C tubes and that was much better.

Even with 6550C tubes it was highly engaging and the musicality signature was superb! Connected to a smaller system comprising of SF monitors and the PV12, marvellous! Then tried it on a pair of ProAc Tablets and it was fantastic! Another system comprised of the big Tannoy Westminster's, equally outstanding. All of those three systems haven't really changed since these were special custom orders and this is going back to 1998.

I wasn't aware that CJ still does the XS version for customers, considering the few decades since these XS versions were offered... Are you sending the amplifier to CJ or is it a private tech who is planning to carry out the mod?

Hope all goes well. Cheers
RJ

[ks9sunset]

Thank you for all the information and experiences on the 11a and 11xs....much appreciated. I have a relatively smallish room and listening distance is approx. 9 feet. The speakers are 92dB efficiency 6" Omega Alinco Super monitors.
I am located in Canada, so most likely will send it to my local tech to do the conversion. I am new to this forum, just wonder if there is a schematic link I can get from CJ to do the conversion?

[Big Dog RJ]

Yes, there definitely should be one here somewhere.
Admin can easily help you with that.

All the best on your mod, it should give you a wonderful sound if that's what you're looking for, those EL34's will always have that special midrange, which to me is highly addictive and totally engaging.

Have a good one now, cheers
RJ

[Timo62]

I would call Conrad Johnson for any information you might need to do the conversion.