diytube.com

has anyone here tried to operate a pair of Mark3's in tandem or parellel to up the wattage to 120 watts or so?

I ended up using the Poseidon boards to drive a pair of 829B tubes per channel, although I didn't quite get up to 120 watts. You might consider a fresh chassis (pair of chassis is more likely) to obtain this goal instead of bridging two monoblocks. I used 829B's for their availability and resonable price point. An 829b is roughly two 807's in a single tube. In fact, if you used four 807's per channel, you could easily reach your power goal. You'll get a very satisfactory result starting with the proper output transformers/power transformers to get the job done.

Hi, Thanks for the info! I have been looking around at starting from scratch, where could i find schematics, specs etc on building a pair of these 829b power amps? I'm off to look up the tube data on these. Thanks much, Kim

That is one cool looking tube! Very interesting pinout.

If your interested in a dynaco 120 watt design, you can review the mark6 schematic. Origially intended for 8417's but can be adapted for kt88/6550.

Also Plenty of marshall schematics on the net for 100watt and 200watt tube amps (major 1966, major 1967, major 1978 models).

Hey, thanks for the info on these amps. I am building my big power amps using the transformers from a pair of old pa amps. I use 6- 6550's for each amp using very low idle current, driven by a 12AT7 & 12AX7. Very low distortion up to 180watts. They are up & running now, still tweeking some values. This is a Bob Carver design. I will post pics if i can ever find a way to upload one on this site. Kimbob

sounds like your making big time progress. I would be interested in reviewing the schematic your using.

I uploaded photos of my amps at http://s537.photobucket.com/albums/ff331/brett37095/ I do not have permission to share or post the schematics, i will ask about this. I got a little carried away with 5 watt metal oxides. The caps are under the board, 7-390uf. They really sound great, but now i need to get speakers that will take it, my klipsch fortes sure are tough though. The drivers are 12AT7 & 12AX7. The 7 pin tube is a 6AL5.

Wow. That's a whole lotta amp.

Nice Job! I would like to demo that on my Magneplanars.

Where is the enclosure from?

Any info on the schematic...you said you were not sure if you could post?

Dave

I built a 120 watt tube bass amp. I'm thinking of replacing the 6AN8 driver with the Poseidon board.

http://home.triad.rr.com/scottvicki/150BassAmpProject.htm

Scott

Hi Scott, Nice work. I've been curious about the kt90's. I do not have enough experiance with guitar amps to know if the posieden would get the sound you want. I do know that I don't like the sound of the 6AN8 in hifi applications. I'm sure someone around here would know. Did you get your chassis & cage from antique audio? I bought from them too & they do have high shipping & handling. My chassis are hammond, they are ok, but the spot welds show. Another good supplier is www.mouser.com Great for resistors,caps,terminals,boards etc. Kimbob