Next Amp: 2a3PSE, 300B or KT88SE UL

[sgerus]

Next Amp: 2a3PSE, 300B or KT88SE UL

I know this may be like asking what’s better, Fords or Chevy, but here goes.

I’m in the planning stage of my 2nd amp and could use some input as to the choice of power tubes.

The first amp is a 2A3 SE…. I like the sound.
Most of the time the music I listen to are vocals, then jazz, and a little classical.

Just thinking of options for the next project:

1. 2A3 push-pull
2. 2A3 parallel single ended
3. 300B
4. KT88 SE ultra linear

The reasons I have the KT88 on the list:
1. low cost
2. I love the looks of that tube
3. This ultra linear looks interesting


Any thoughts?

[andyjevans]

I'm deducing from your choices that you'd like a bit more power. If you want to join me for a thread, the next amp I want to build is an all-DHT PP2a3 one. I've stuck with PP as a topology, and I'm just moving up the sonic ladder with the choice of tubes. I'm guessing the end of the road is something like 26 into 71a into 2a3. 26 could be swapped with a 12a, and 71a with a 46. anything like that. I intend balanced all through, with diff pairs and CCSs underneath. Cap coupled with teflon caps.

The challenges for this build are all solid state - the filament supplies and the CCS bias supply, and maybe a CCS under the output tubes even, though I'm thinking cathode bias right now. Certainly a complex power supply, with chokes, polypropylene PSU caps etc. So likely to be two monos.

You haven't included the 845 - a low power (450v) PP amp with these would be good too. I think after the 2a3s you'd be disappointed with both KT88s and ultralinear. I'm personally going with 2a3 and/or 845 because they're cheap in basic Sovtek or Chinese flavour, and I prefer a thinner more focussed sound than the usual 300b amp.

Depends what sonic flavour you like - big and warm or clean and precise. Also speakers, source equipment, room size, listening material etc - what are they?

[Kent Smith]

I prefer an incremental approach: try the 2A3's in PP before you try pentodes. You might consider using an interstage transformer, it keeps the circuit simple and sounds very good to me.

[SRMcGee]

Folks:

This sounds interesting -- I'm also considering building a new tube amp. My priority is sonics (cost is less of an issue) and a design that is suitable for a relative novice. I'm using an AES SuperAmp Signature right now and would like my next amp to be a qualitative step up. That said, I also need at least 15 watts (preferably 20). If you have an idea for a suitable project, I'd be inclined to join in.

Regards,
Scott

[sgerus]

OK so the first 2 replies like 2A3 PP…
Will be interesting to see a general consciences as more replies come in.

On the plus side for PP is the option for ccs (on the 2A3’s) as Andy mentioned.

Any reason why you like PP vrs Parallel Single Ended?

[arnoldc]

I'd go with PP 2A3 as well. Have considered Frank's PP 2A3 somewhere in this forum, but Ithink I would like to use an interstage this time to keep it simple and since I haven't done any IT coupled project yet, it is self serving.

I have considered both PP and PSE and based on what I've gathered in the past from various opinions as well, it seems PP is much more of a better option.

This forum had an EL34-inspired PP project with the design coming from the hard core folks in particular Wayne (cogsn.. something). How about this folks, a DIY Audio deigned PP 2A3??

[andyjevans]

How about this folks, a DIY Audio designed PP 2A3??>.

Well, you've got my vote here. should we carry on in this thread or start another called "a DIY Audio deigned PP 2A3" - not sure where the original poster wants to go - it's his call. Andy

[lndm]

Originally posted by sgerus

first amp is a 2A3 SE…. I like the sound.

This won't be easy to beat, especially if you get into PP. If it's more power you wan't, why not try a larger OPT, more 2A3's in parallel, and a beefier power supply?

3. This ultra linear looks interesting

Yes, it is, but compared to SE 2A3?

[batinal]

I intend balanced all through, with diff pairs and CCSs underneath. Cap coupled with teflon caps.

The challenges for this build are all solid state - the filament supplies and the CCS bias supply, and maybe a CCS under the output tubes even, though I'm thinking cathode bias right now.

Andyjevans,

Could you tell me what CCS stands for and what's so good about it?

Thank you very much.

Kay

[andyjevans]

I've been reading some user experiences of the Edcor interstages at www.edcorusa.com particularly the 10k-10k. Maybe this could go in the mix. No DC possible - parafeed sounds good apparently. Also could be an input transformer

Here's another idea using it:

http://db.audioasylum.com/cgi/m.mpl?...ge&r=&session=