Help with Tubelab SE component selection

[zman01]

It's in post #126 here http://www.diyaudio.com/forums/tubelab/157491-pictures-your-tubelab-amp-3.html

Beautiful - your amp looks very nice! Probably enough people have told you already, and 430 man hours is no joke - but the results are sweet . I see it's the Tubelab SE with 300B.

Now that you've been using it for quite some time, how does it sound campared to other amps you've used?

 

[boywonder]

it makes the sweetest 8 watts of anything in the house..

...... how does it sound compared to other amps you've used?

Thanks for the comments, it's my favorite.

Caveat: I have 95db sens full range speakers.......

 

[zman01]

Caveat: I have 95db sens full range speakers.......

By full range you mean single driver? Which make?

 

[boywonder]

Yes, single driver. Started out with Fostex F207e in Half Changs, now running TB W8-1772's in the Half Changs, both with a sub.

 

[zman01]

I'm running single driver full-range units too. Have the subs, and run them in bi-amped config too when I fancy.

 

[zman01]

Tubelab has used this in his TSE with 45 tubes with good results:

Transformer - One Electron, Output, 4800 to 16/8/4 | Antique Electronic Supply LLC

IIRC Russ also has/had this in his TSE?

Anybody tried the UBT-2 in their Tubelab SSE?

I have decided to stick with a SE build first, and for the tubes plan to use EL34. The slightly lower primary impedance of 4.8k vs 5k recommended at Tubelab site for SSE builds - that should be ok?

 

[zman01]

I have decided to stick with a SE build first, and for the tubes plan to use EL34. The slightly lower primary impedance of 4.8k vs 5k recommended at Tubelab site for SSE builds - that should be ok?

Typo identified - it should read I have decided to stick with a SSE build first!

Apologies for the confusion.

Did some reading on the net and looks like the EL34 tubes work well with OPTs within the range 4.8-6k primary impedance. I guess the One Electron should be fine.

 

[boywonder]

I have decided to stick with a SSE build first, and for the tubes plan to use EL34. The slightly lower primary impedance of 4.8k vs 5k recommended at Tubelab site for SSE builds - that should be ok?

It will be fine. Looking at Tubelab's "tubes and transformer" page for the various tubes and output transformers; he lists the EL34 with 3K and 5K loads at varying B+ voltages. Anything in between these will also work fine, think of it a as a continuum. Note that the power out numbers are for triode wired tubes. Generally, as the load on the output tubes decreases, the power goes up and the distortion goes up.

Tubes & Transformers

Note the red font in the tables, these conditions are where the combination of idle current and B+ exceed the max dissipation rating for the tubes. Many tubes will happily operate over their power dissipation limit, but their lives will be shorter than operating at lower power.

 

[zman01]

Boywonder,

Thanks for confirming and sharing the link - will go ahead! It'll take me quite some time to get all the parts, so probably build will happen mid July.

- Zia

 

[victorm]

Hello everyone, my first post is unfortunately a little long. Apologies for that.
Just ordered a Tubelab SE board from George and going through the part list in preparation.

Hope someone can help me with a couple of things:

PQ5EV5 voltage regulator is listed on Digikey and mouser as OBSOLETE. They still have quite a few, but as soon as they sell them that'll be it. Is there a replacement recommendation?

High voltage MOSFET's:
Original schematic on the Tubelab web site specified 2SK2700 which is listed as OBSOLETE by Digikey and mouser, and neither of them have it any longer. (you can still get it on eBay but it will disappear soon I think...)

The part list specifies 2SK3563 (higher current - is that necessary?) - but again, it's listed as OBSOLETE, neither Digikey nor mouser have it any longer. Not even eBay.

Appreciate any suggestions,

Cheers,
-Victor

 

[boywonder]

High voltage MOSFET's:
Original schematic on the Tubelab web site specified 2SK2700 which is listed as OBSOLETE by Digikey and mouser, and neither of them have it any longer. (you can still get it on eBay but it will disappear soon I think...)

The part list specifies 2SK3563 (higher current - is that necessary?) - but again, it's listed as OBSOLETE, neither Digikey nor mouser have it any longer. Not even eBay.

Appreciate any suggestions,

Cheers,
-Victor

I'm using the 2SK3564 in both of my Tubelab SE's, they are 900V rated instead of 500V rated and are still available at Digi-key. The 2SK3563 probably has slightly better Crss but the 500V source-drain voltage rating is a little tight even in my 45 version of the amp.


Here is a related thread (and there are a few others...)
http://www.diyaudio.com/forums/tubelab/181369-mosfets-tubelab-se.html

 

[victorm]

Thanks boywonder. Digikey don't have the 2SK3564 any longer ;-( Mouser still have a few. I also remember someone on this thread talking about using the 2SK3565 - they are still available.

Hopefully I will get the board soon and then will see what is available.
Cheers, -Victor

 

[zman01]

Power transformers

Previously had my mind set on the Hammond 373/374BX power transformer for my SSE project.

Came across this on the Edcor site:

EDCOR - XPWR002-240

Power transformer for a 240V, 50/60Hz. line to 720V (360-0-360) at 220mA center tapped, 60V at 800mA, 6.3V at 7A and 5V at 4A.

Price is around 1/2 of the Hammond models... specs look good to my newbie eyes.

Also would this be suitable for a future TSE build? Then I can think of buying a pair and save on the shipping maybe.

 

[rknize]

It's overkill in terms of VA, but it will work just fine. I used the XPWR035.

 

[boywonder]

Also would this be suitable for a future TSE build? Then I can think of buying a pair and save on the shipping maybe.

If you are going to buy a pair, consider buying the XPWR002-240 and the XPWR131-240 for an additional $7 or so total. The XPWR131 was commissioned by none other than Rknize for the TubelabSE; it has two sets of secondaries to allow either 300B's or 45's/2A3's to be used in the TSE.

Russ paid the NRE to have this P/N made and now the rest of us get to benefit.

Thanks again Russ!

 

[rknize]

Haha...NP. I didn't mind helping out with that and I refused to use a Hammond.

Sorry, I didn't see the other part of your question. The transformer you selected would be too hot for a TSE.

 

[zman01]

Russ, Boywonder thanks for your replies, and special thanks to Russ for getting a new part number in place for the DIY community!

My investments on the 300B TSE till date amount to the ordering of a TSE PCB only. If I order the XPWR131-240 that means another brick in the wall, and brace myself for the $$$ that's required for a quality 300B.

If I decide against the TSE build, would I be able to use this for another Tubelab PP project? The ratings look kind of close (660v vs 650v recommended for the EL84 based PP).

For a guy who is a total newbie and still in the process of building his first Tubelab PP (with a lot of help), these are big thoughts maybe.

 

[victorm]

Hey guys, need some advice ;-)
Got the Tubelab SE board and preparing the components now (300B based version). As shipping to Australia in not cheap, I'd like to make sure right things are ordered. Have read George's notes and narrowed down the OPT choice to One Electron UBT-3 vs EDCOR CXSE25-8-3K. From what I can see, there are opinions favouring either side, but I have not seen any comments form anyone using the Big EDCORS with TSE? Please let me know any feedback - really appreciate your help.
Cheers,
-Victor

 

[Tubelab_com]

From what I can see, there are opinions favouring either side, but I have not seen any comments form anyone using the Big EDCORS with TSE? Please let me know any feedback - really appreciate your help.

I tried both.

The short story.....I sold the One Electrons at the Daytom Hamfest a few months ago and my TSE uses the big Edcors.

Details The One Electrons sounded pretty much the same as the Electra Prints that are in my other TSE. The big Edcors have a lot more bass, and give up a little high end. The second TSE uses 307A tubes that just seem to like the Edcors better.

Note the One Electrons that I had were 3K ohm and the Edcors were 5K. I also have a bunch of 3K Transcendars, so I sold the OE's.

 

[victorm]

Thanks very much for this! This seals my decision to go with the Big Edcors ;-) which should hopefully go well with the XPWR131-240 and CXC125-10H-200mA.
Just on the other topic - does anyone have any volume pot recommendations? I was thinking about Potentiometer - 100K Dual, Linear PC Mount, 3/8" Bushing | Antique Electronic Supply LLC...
Any feedback is greatly appreciated.
Cheers,
-Victor