DiyTube Driver Board vs Curcio Board

[hilldweller]

Has Anyone Had Experience With Either Or Both Of These Boards? How Do They Compare Besides Curcio Costing More $$$ Yellow_Light_Colorz_PDT_14

[WA4SWJ]

Hi,

I have only had experience with Shannon's ST-70 boards - I have two of them - one in an old rebuilt ST-70 and one in a newly built ST-70 clone. All I can say is that they are my best sounding amplifiers by far and I have a lot of amps. Not as many as build-master-McNally, but quite a few. I can highly recommend Shannon's board (and I'm not just kissing up).

I don't think you can do very much better without major additional changes to the amp. BTW - both of my ST-70's have solid state power supplies and sound punchier (if that's a word) than they did with tube rectification. I like that sound. Some may not.

Good luck and send pictures! We love those pictures!

Regards,

[hilldweller]

Hi,

I have only had experience with Shannon's ST-70 boards - I have two of them - one in an old rebuilt ST-70 and one in a newly built ST-70 clone. All I can say is that they are my best sounding amplifiers by far and I have a lot of amps. Not as many as build-master-McNally, but quite a few. I can highly recommend Shannon's board (and I'm not just kissing up).

I don't think you can do very much better without major additional changes to the amp. BTW - both of my ST-70's have solid state power supplies and sound punchier (if that's a word) than they did with tube rectification. I like that sound. Some may not.

Good luck and send pictures! We love those pictures!

Regards,

Thank You For The Reply And Yes, I Will Supply Pics. I Just Recieved My Ebay Win Today And Have Yet To Start The Project. I Was Fortunate Enough To Win An Original Unmodded ST 70 In Super Shape With All Original Tubes And Parts Except For The Rect. Tube, It Is A Zenith. I Will Be Providing Before And After Pics For All To See. I Love To See Everbodys Pics As Well. Very Exciting And Inspirational!

[hilldweller]

What About Those Weber Copper Tube SS Rects?

[erichayes]

Zenith didn't manufacture tubes; they bought from other manufacturers and had their name silkscreened on the bottles. Look carefully for small lettering saying "Made in Great Britain" or "Made in Holland". If you find the former, it's a Mullard; if the latter, it's an Amperex. In either case, it's a commodity.

If it's labeled "USA", it's probably a Sylvania, which is still worth more than chump change.

[TerrySmith]

I tried the Curcio boards on my MK-4's long before Shannon introduced the ST-70 / Poseidon boards.

The Curcio boards use a cascode- triode gain stage and a stock cathodyne PI. These boards are not silkscreened or have any solder mask, just bare fiberglass. This mod sounds as dull as dishwater! Yellow_Light_Colorz_PDT_21

On the other end of the spectrum is Shannons Diy boards, which uses the long tail pair PI, which is what your ST-70 / MK-3 needs. These also look nicer with the red solder mask!

[hilldweller]

I tried the Curcio boards on my MK-4's long before Shannon introduced the ST-70 / Poseidon boards.

The Curcio boards use a cascode- triode gain stage and a stock cathodyne PI. These boards are not silkscreened or have any solder mask, just bare fiberglass. This mod sounds as dull as dishwater! Yellow_Light_Colorz_PDT_21

On the other end of the spectrum is Shannons Diy boards, which uses the long tail pair PI, which is what your ST-70 / MK-3 needs. These also look nicer with the red solder mask!

Thanks Terry, I have allready ordered two but i haven't heard from him yet. Must be busy...
I truly appreciate everyones help on this forum. You guy's are GREAT!!!
I will keep posting project progress. Right now, i'm just getting things together.

[Shannon Parks]

I think Curcio's boards are coming at a different angle than mine, so I think I can make a fair comparison between the two.

If going the Curcio upgrade route, I would encourage folks to go the whole route and also use his power supply. At that point, it really is a different amp, with a different sound and tight regulation. This is what some people want as many feel the ST70 was a bunch a compromises, and Curcio seeks to address those. A big bonus of Curcio is that he supports his boards with a great website, forums and downloadable manuals. He's very professional and he uses those prices to deliver better product support, no doubt.

My board is meant more as a standard upgrade of the 7199 boards. I like the tube complement and LTP (with a twist due to the CCS). The design is pretty much a time tested modified Mullard design dating back 50 years. It isn't a radical update to the ST70 in my opinion, in particular where I still recommend that folks can recycle the can caps (near heresy, but I like simplicity!).

[MarkC]

I have used both the Curcio and Triode boards in my ST70. Joe Curcio helped me with some
trobleshooting on the Triode board and after talking with him several times, I decided
to give his board a try. It's a nice board and sounds better than the Triode
board IMO but I like the DIYTUBE board best. Joe Curcio is very knowledgeable and
like Shannon said, his support for his products is first rate.

[soundmasterg]

Which Triode board did you try? I assume these are the ones that SDS makes for them? I was going to try one of the dual EF86/12AU7 boards that Triode sells, and also have the power supply stiffening board that they sell. Any comments on either of these?

Greg

[MarkC]

The board I bought uses the dual EF86. I ordered the board pre-stuffed from Triode since
it was my first venture into amp rebuilding. It sounded horrible. Long story
but I asked Joe Curcio to take a look at it to see if he could figure out what was
wrong and he determined that the board had some incorrect value resistors.
I corrected those and got the amp working. I also have the SDS cap board in it
which I used with the Curcio board and the DIYTUBE board. The Triode board
is very nice sounding and is used by a lot of ST70 folks. I just happen to like the DIYTUBE board better.

[Blackburn Audio]

what values were off on the Triode board? I have built hundreds of these EF86 boards and installed many as well and always get good results with them. In fact I'm listening to one in our ST70 in the front of the shop right now. When we first came out with the 6AU6 version it need some tweaking of the plate and cathode resistors to get the biasing correct since the output of the pentode is directly coupled to the grid of the 12AU7 but the EF86 version we have had around for so long that the parts on it are well tested and set. Just wondering if one of the new guys we had here awhile ago stuffed the wrong part or something?

-Matt at Triode Electronics

[soundmasterg]

Thank you for your comments. Are you saying that the recommended resistor values were incorrect or that they had put the incorrect value resistors on the board? I ordered mine not stuffed and will do that part myself, but I was going to go off their recommended values. If they have the wrong values though, I'd like to get the correct ones in there.

If I can get the ST70 sounding decent with the Triode boards, then I will be happy with it as is. I've got a Scott 299B to rebuild also among other projects so I won't be spending all the time in the world messing with the ST70 but would like it to sound better than stock.

Greg

[Blackburn Audio]

The parts values listed in the instructions are correct without a doubt, thats why I was wondering which resistors in his board were off since I know the parts list is correct. The sound of these boards is an improvement over stock although the circuitry isn't that much different than the original dynaco circuit. just uses better tubes for the job and upgraded components from the original boards. My favorite combination is the EF86 board with a JJ ECC99 driver tube.

-Matt at Triode

[MarkC]

what values were off on the Triode board? I have built hundreds of these EF86 boards and installed many as well and always get good results with them. In fact I'm listening to one in our ST70 in the front of the shop right now. When we first came out with the 6AU6 version it need some tweaking of the plate and cathode resistors to get the biasing correct since the output of the pentode is directly coupled to the grid of the 12AU7 but the EF86 version we have had around for so long that the parts on it are well tested and set. Just wondering if one of the new guys we had here awhile ago stuffed the wrong part or something?

-Matt at Triode Electronics

The board I got from Triode was stuffed with the wrong value resistors.
It was not a case where the design was bad. When I installed the board,
like I said, it sounded terrible. Out of frustration, I put it aside for a while
and by the time I was ready to try to troubleshoot the problem again, I mistakenly
called Joe Curcio thinking I had bought the board from him ( I was VERY new to this game).
Anyway, he offered to help troubleshoot it for me even though it wasn't
his board. He measured the values and determined they were incorrect.
Looking back, I should have sent the board back to Triode but
so much time had passed that I decided to just fix it myself.