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Considering the Threshold 400A...

Its the earlier (earliest?) cascoded version. It has 4 wires on each side going from the driver board to the output board and there are no visible driver transistors. One pair of the heatsinked TO-92s are the pre-drivers, and the drivers are the same as the outputs, fourth transistors from the rear on the output boards.
 
FootFungus said:
Its the earlier (earliest?) cascoded version. It has 4 wires on each side going from the driver board to the output board and there are no visible driver transistors. One pair of the heatsinked TO-92s are the pre-drivers, and the drivers are the same as the outputs, fourth transistors from the rear on the output boards.
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Is there any consensus as to which models sound better? Are the cascode models better sounding?
 
I like the cascode models better. Your model is still a triple darlington output stage, so I might have a bit better bass response than the later models into certain speaker loads.
 
I have the 400A now. It's better than the Kenwood 700M. The 700M is a nice amp. Really nice to look at and to listen to. But, the Threshold 400A is positively amazing. What the 400A excels at, which the 700M does not, is clarity. Phenomenal clarity and separation of sounds and instruments, especially in the upper frequencies, but all throughout.
 
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That's splendid to hear. Make sure to check the fuses. They should be quick blow and match the values written by the respective fuse holder. You might consider putting in lower value fuses given your speakers. Those are the only line of defense against faults. Double check the DC offset, and make sure the temperatures on the left and right side heatsinks aren't too far apart.
 
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FootFungus said:
That's splendid to hear. Make sure to check the fuses. They should be quick blow and match the values written by the respective fuse holder. You might consider putting in lower value fuses given your speakers. Those are the only line of defense against faults. Double check the DC offset, and make sure the temperatures on the left and right side heatsinks aren't too far apart.
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Thanks for the tips. I'll check the fuse value today.

DC offset came in at. .11mv and .19 mv respectively.

I continue to marvel at this amp. Few times along my path of audiophilia has there been such a major step up. What I'd say is that I now want to spend loads of time listening to my music. I am excited again. It's made me fall in love with music again, which should be the whole point of what we are doing here, right? If my system now looks mismatched, I could care less. All of my components are happily married. I think I've come close to complete audio sublimity. It's all there, surrounding me, almost tactile.
 
Those are excellent readings, especially since there are no DC offset adjustments. You did well on that purchase.

The driver board caps look like they may be original (or fairly old at least). At some point, when you are bored you might go change those out. There are 2 47uf caps and 1 470uf cap per driver pcb board. There also might be 1 0.15uf tantalum cap that can be replaced easily with a film cap.
 
FootFungus said:
Those are excellent readings, especially since there are no DC offset adjustments. You did well on that purchase.

The driver board caps look like they may be original (or fairly old at least). At some point, when you are bored you might go change those out. There are 2 47uf caps and 1 470uf cap per driver pcb board. There also might be 1 0.15uf tantalum cap that can be replaced easily with a film cap.
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Thanks for the tips. I totally intend to recap. There's a slight buzz that I am trying to get rid of. I don't think it's a cap, but it could be. The buzz is in one channel. A minor blemish in an otherwise amazing sounding amplifier.
 
I have a Threshold 400a, late Cascode version that I recently had recapped/rebuilt by Jon Soderberg. Wow, and I thought the amp sounded good before...now it sounds just beautiful. Highly recommend his work. Not cheap, but definitely worth it!
 
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