A box arrived.

[Legrace]

Are you using an active crossover for the tri-amping? Sony made a nice one back in the 70's.

With the components I'm using passive is all I require. Preouts from my SS are wired into my sub. It has a high pass filter that passes only 80hz and above over to the M125's which are next in line. The M125's then connect to low taps of my Tannoys. Finally the speaker outs of my integrated connect directly into the high taps of my towers. In summary:

1) low bass 80 and below assigned to SS sub, 500w SVS SB2000
2) upper bass above 80 and mids: M125 tubes in triode mode
3) high freq: SS, 100w/ch Marantz PM11S1

So SS/Tubes/SS triamp. Connected in the manner described the main volume control of the integrated regulates all three amps in unison. They all scale together seamlessly.

When I first built the M125's I had the preouts going directly into the M125's and was running them full range into the towers. Had no clue about biamping or triamping. Without adding anything today I am tri amping and consider it a distinct improvement. Quite amazing how many different ways one can plumb the same system!

 

[gadget73]

try it triode with 2 tubes.

also might be worth trying different speaker impedance taps for to alter the loading.

maybe you still won't like it, but its fairly easy to try and maybe it will produce sonic nirvana for no major effort.

 

[Lavane]

try it triode with 2 tubes.

also might be worth trying different speaker impedance taps for to alter the loading.

maybe you still won't like it, but its fairly easy to try and maybe it will produce sonic nirvana for no major effort.

The speakers I'm using are rated for 6 ohm. The 4 ohm tap sounds best as it did with my ST-70. When I first fired uo both amps together I tried just two tubes. Triode mode sounded pretty much the same as with four.

 

[gadget73]

well, sometimes it is what it is. Find the best performing reasonable combination of things and roll with it.

 

[Legrace]

Hope you are enjoying the fruits of your labors. I went from elation, to despair, and back to elation once I added the AB boards. I recently decided to extend the wood trim across the front of my M125's (covid project, we are currently in lock-down, most everything is closed), plus added some labels which I printed using my ink jet printer. My SO approves, as the amps now better complement the wood panels of my R2R and Dolby units .

 

[Lavane]

Hope you are enjoying the fruits of your labors. I went from elation, to despair, and back to elation once I added the AB boards. I recently decided to extend the wood trim across the front of my M125's (covid project, we are currently in lock-down, most everything is closed), plus added some labels which I printed using my ink jet printer. My SO approves, as the amps now better complement the wood panels of my R2R and Dolby units .

View attachment 2208065

Very nice! I wanted to use Maple, but couldn't find any locally. Wood has gotten stupid expensive here and the selection of hardwood has thinned out. So I used a few pieces of Mahogany for the sides until I get some Maple. Is your wood wrap just held on by the screws on the sides? Bob doesn't sell those AB boards anymore. So did you remove yours? I know the newer AB boards have a relay on them and whatever other changes made. I like mine very much so far. I will be getting some 12BH7's to try. The JJ EC802S long plates sound good though.

 

[Legrace]

I used leftover material that I got a few years ago, no veneer, hardwood through and through. Even then it wast cheap so I can only imagine about today. I only had a tiny piece remaining but it was just enough for the two amps. I glued the front to the sides at the corners. The resulting frame slides out from the front and is held by the rear screw only. Remove it and the works can be slid forward to provide access for working on an amp.

The AB boards are the only reason I still have these amps. I will never remove them. Mine have the isolation transformer which greatly increases reliability.