Tubelab SE board for PSE

[ystkkmkr]

Hello Tubelab fans,

For my electrostatic speakers, I am planning a pair of Tubelab 300b PSE monos, using two boards.

If you have an experience of paralleling the TSE output stage, what was your configuration for the other stages? Any comparison for better sonic performance?

If you were me, how would you proceed your experiment?

Thank you,
Yoshi

[Evenharmonics]

I've built a TSE monoblock which was discussed here. My reason for this was to use TSE for center channel of my home theater setup which doubles as stereo system (already using TSE for L & R speakers) so that I would have matching s.e.t. sound for front 3 speakers.

Given the parameters of output tubes and transformers that can be used for TSE, I'm not sure how beneficial it would be to go mono for dealing with electrostatic speakers. What's the spec like for your speakers?

[rknize]

Are you building two monoblocks with two board each? ESLs are a tough customer for any SE amp. Have you thought at all about push-pull?

[ystkkmkr]

Evenharmonics,

Let me tell you my tube amp history. My first tube amp was a direct coupled 6c45-2A3 SE stereo (free-lunch, DRD type), which was originally built to drive my AKG K1000 ear speakers. The stereo amp unexpectedly performed well to drive my somewhat inefficient and low impedance Martin-Logan Aerius (89dB, 4 ohm, perhaps). Then, I transformed it into a pair of monoblocks for improved channel separation. Now, I would like to use 300b without exceeding 450-500V of B+. This is why Tubelab parallel SE monos have come to my mind for even better driving capabilities, leaving out direct coupled 300b options. When I ordered TSE boards last week, I learned that George had done wiring a board for PSE several different ways. So, I'm wondering how many people have done this, and whether or not I better leave whole one channel (or a stage) unpopulated.

I might eventually replace 5842 with trioded D3a by DIYing a socket converter, but I think this should be another topic.

[Evenharmonics]

Originally Posted by ystkkmkr

The stereo amp unexpectedly performed well to drive my somewhat inefficient and low impedance Martin-Logan Aerius (89dB, 4 ohm, perhaps).

Given the typical output of 300B s.e.t. amp of around 7 watts, 89db speaker may not benefit much from it. Even at 8 watts, your speaker may reach 98 db at 1 meter which isn't much.

To make this type of amp truly beneficial, you will need more efficient speakers (95db or higher). If you want to keep your speakers, you can either listen at relatively low volume only with TSE or you may want amps with higher output capacity.

[rknize]

Just to back up a bit, you are saying that your 2A3 SE amp (4 WPC?) performed reasonably to you ears and so you are hoping to build a 300B amp instead? Parallel 300Bs for a bit more? While I agree with Even that such an amp is not really up to the task, it's really a matter of personal taste.

It seems like one source follower in the TSE should have no trouble driving both 300B grids, but they would need to be reasonably well-matched. With the appropriate OPT, 14WPC should be possible.

I happen to have a friend that owns a pair of ML Aerius speakers. He drives them with two stereo SE amps (each bridged) and the setup was able to fill the living space of his previous home quite well. It was an open floor plan. They were beefy amps, though. Bridged they are 4 6L6GCs per channel.

[rknize]

OK, make that six 6L6s per channel. I remembered which amp it was...the Golden Tube Audio SE-40. Beefy indeed.

[ystkkmkr]

OK, I will simply wire the two TSE board channels in parallel to get 14 watts, and check how it fits my relatively low volume listening. Thanks.

Russ,

I think I will still prefer the sound produced by SET.

[tubelab.com]

It seems like one source follower in the TSE should have no trouble driving both 300B grids,

Doing this way will force one bias adjustment for both tubes. This would require well matched tubes.

The prefferred method is to lift the end of one coupling cap where it is connected to the 5842. Wire this cap to the plate of the other 5842. So now one 5842 has two caps connected to it. This tube is now the driver for both output tubes. the other 5842 can be removed.

You can tie the plates of both output tubes together through a common OPT, or you can use two OPT's with their secondaries paralleled

[tomchr]

Do you need a different OPT, though? The effective Rp of two tubes in parallel would be half that of one tube so it would make intuitive sense that the OPT primary impedance needs to be lowered by half as well.

I can't quite wrap my head around how the load lines would look like for the two output tubes in parallel. Could someone shed some light on this?

~Tom