Going down the tubes

Recently bought a used (obviously) Audio Research LS22 pre amp. I am planning on rolling some tubes and recap the electrolitics. I am going to make a new aluminium top and bottom plate, since the original ones are made out of crap steel. There is no PCB layout (that I can find) so momentarily reverse engineering. It is fully balanced from input to output and has an “old fashioned” 4 deck potentiometer for volume control. It sorta looks like my old 4 cylinder Jeep Wrangler. Simple but effective. Now I fired it up and while writing this I feel this sense of happiness crawling up my spine. This is the first time I heard tubes and I must say… Wow…!


There is a 10audio.com article dedicated to step-by-step upgrade of the LS22. Is that what you’re using as a guide? Looks like a fun project.


Yes, most of it.


I hope you can find the time to post pics of the various steps in this project. This is the kind of stuff a lot of us live for.


Please elaborate on that. If you literally mean you had not heard tubes prior to this, it would be…helpful.

I just installed an Audio Research Ref 6 Pre in my system instead of the BHK Pre. The BHK Pre is going up for sale. I guess a $14 k retail preamp should outperform a $6k preamp. Was surprised at the more realistic characters that have entered my living room. The soundstage is deeper and more refined.

No, not that I know of. I sorta ignored tubes as being slow, deteriorating, old school tech not worth while paying attention to. I designed amps a short while with BJTs, later with FETs. FETs are nice and easy. Friggin’ fast and strong. High impedant where you need it, very low impedant where you want it. But now the budgets are better, more time on my hands to play around I decided to try a tube thingy called the BHK300. Had that in the house for a month or 2 but sold it back to my dealer. Now by fate I stumbled upon a AR LS 22 pre amp, almost as old as I am. Swapped it out with my multi million dollar Ayre KX-R Twenty and you know what: The Ayre goes out. Honestly…? That thing is so crazy expensive and it has some nice ideas incorporated. But you can not hear the solid aluminum or the damping feet. And that’s where the money is going into. Now if you open that simple LS 22 you’ld be surprised by the simplicity of it all. Volume control by a 4 deck potentiometer https://www.ebay.de/itm/ALPS-RK27114MC-Motorpoti-4-fach-quad-Audio-Dreh-Poti-RK27-Potentiometer-Motor-/350656704029. No chippie doing nothing.

I hope this answers your question, I liked answering it, appreciate your interest.


I’ve recently begun to add tubed gear into my rig. @Paul ‘s BHK video was in part the inspiration. Paul said that tubes simply add something special to the sound. Unfortunately, even though many other companies (Rogue, PrimaLuna, Vincent, etc) utilize tubes in their entry levels, PS Audio doesn’t introduce tubes until far up their line. I realized that I was not going to be able to afford tubes in the PSA universe which led me to sell off all of my PS Audio gear in order to explore tubes.

I’m not crazy about tube amps, thus have focused on tubes before my solid state amp amp. So far I’ve added the tube rectified Border Patrol SE-i DAC and the Decware ZBox tube buffer. I love both! They add an atmosphere that my pure solid state PSA rig was unable to achieve.

And I love shopping for vintage NOS tubes. The history, the different flavor of sound, the factories in which they were made, country of origin, etc. I love the notion of being able to add a 1950’s Telefunken to color. I love how the tubes glow. Looking forward to further adding tube pieces .l


It’s like collecting stamps, only cheaper… Hahaha
Nice to have something to do when we all have to stay home… :yum:

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Project is finished:

Changed/upgraded coupling caps with Mundorf (8x5uF)
Replaced rectifier diodes (8xStealth)
Removed fixed power cord, added IEC chassis connector
Swapped tubes
Checked all caps
Applied the 6dB attenuation mod from AR service center (8xresistor)
Cleaned everything up
New 4mm aluminum top and bottom cover
3 damping feet
Made a LTSpice model of it for future reference and trouble shooting


Next project: Red plating BAT AK55 power amp…

Rectifier tubes in a DAC adding atmosphere…now I have indeed heard everything.

Tube preamps are great but the really good stuff comes with tube amps. I love my KT88-based tube amp.


I agree @speed-racer, I just bought a brand new pair of MC275’s for bi-amping my ribbons, still waiting on them. They are being build as we speak, since I wanted consecutively serial numbers to keep the street price up. Also bought a used BAT AK55 for my office set. The latter is showing red plating when I drive it all the way up. So that’s going to be my new project.

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I would, never trade my kt88 amps for nothing.
I am With you on that.

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I’m just finishing off paying for a PrimaLuna Evo 100, should have it in just over a month, can’t wait. Looking forward to getting some KT88’s in there!


Great project ronaldwanders. The big problem with those projects is you just can’t do one! And thanks for the pics.

For those of you with prima luna gear, the tube rolling possibilities are spectacular, from just the center 2 pre-amp 12AU7s to the range of EL34s, 6L6Gs, and at least 6 different KTs. Let the tube collecting begin!


My PrimaLuna arrived, and I’m over the moon. It’s all stock currently, want to burn them in for when I get some proper speakers in February so I can hear the stock sound before rolling in some Mullard NOS 12AX7’s I have and probably some Gold Lion KT88’s


Another prop from me for PrimaLuna tube sound. I loved my Dialogue Premium integrated with Gold Lion KT88, then grabbed an opportunity on a Dialogue Premium preamp, and the step up in sound blew me away. The preamp significantly added more texture, body, depth and bass, and that was while using it as a front end to the integrated. Now, a Dialogue Premium amp has replaced the integrated and everything went up another level.

Even so, my PrimaLuna dealer is an Audio Research dealer. 15 years ago I lusted after the ARC Ref 3 preamp, but it was way above my budget. Now I’m seeing the Ref 3 selling for a far more affodable price. As good as the PrimaLuna pre sounds, he claims it would be no match for the Ref 3. So now I’m wondering.

Does anybody have any thoughts about that? From a build quality standpoint, the PrimaLuna seems to be superior with point to point hand soldering vs the ARC circuit board approach.

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Hello audiojerry. See if the dealer will let you do an in home demo.

While I have not herd the ARCs, I started my journey with the PL Dialogue preamp and HP amp with focal 1028 be speakers and PS audio’s DMP and DAC. Adding a second HP amp and going to mono blocks was a tier 1 level improvement. Then I went to rolling some preamp tubes. It was like fine tuning the system. Finally I added sub-woofers and room treatments. These probably should be done first in any upgrade strategy.

Anyhow, if you’ve been waiting 15 years, neither of us are getting any younger, so go for it!

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