diytube.com

Im looking at building a beefed up version of the ST70. Build 1 already that incorperates alot of upgrades but I went with Triode Trannys the whole way.

I want to try Hammond 1650N Outputs... But how about an OVER BUILT/OVER SPEC Power Tranny? Sugestions and Sources?

Thanx

Justin

The Triode or Dynakit replacement is way better than stock, should be exactly what you need.

I want a power tranny that is over built and allows for use of KT88s. The Triode vs is beefer, but I wanted even bigger. Some have gone to torodal type... any part numbers or other others? Something really big from hammond. Maybe a P-T278CX Secondary: 400-0-400 V, 465 mA
Filament winding: 6.3 V, 6 A CT.

If you go with Hammond, I would go with the 300 series. They have a 120v primary. The 200 series are only 115v. It will run a lot cooler...

any sugestion on a specific model?

I want to be able to use almost any rectifer ... and just have it over built.

justinsweber wrote:any sugestion on a specific model?

I want to be able to use almost any rectifer ... and just have it over built.

Antec toroids are "over built" (whatever that means).

Below, the transformer has 400V x 2 secondaries with 500 ma per secondary. You could series the secondaries at 400-0-400 for a FW rectifier or parallel the secondaries for a FWB rectifier. You'll get about +565V from either configuration.

At 54 bucks, what a deal.

It also has (2) 70 volt bias taps. The 2 taps can be put through a FWB for about -100V bias voltage. Pretty cool.

When I get some funds, I will get one for a stereo SE 813 amp in triode mode. I am going to use it with a voltage doubler. With a doubler, you can tap off half of the voltage to run the drive circuity. This avoids dropping the full B+ with resistors.

http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... 0192771510

Has anybody tried this toroidal xfmr from Toroid Corp of Maryland? .75A on the secondary HV looks really hefty for an ST70.

http://www.toroid.com/standard_transfor ... s_tube.htm

Yes and it barely gets warm driving this amp:



It's a very beefy transformer.

Regards,

Ed,
That's exactly the setup/layout I have in mind, but with the power section on the left side of the chassis. Got the same diy driver board, too.

Can you describe what you used for rectifiers and regulation circuit?

Well, I used a couple of 1N5408's in a full wave rectifier. I'll have to look under it to remember what else I did. It's been a while since I built this amp. BTW - it is an excellent sounding amp. The output tubes are JJ KT-77's.

I'll look at it this evening and maybe I can post some more pics for you to look at of the underside.

Regards,

Ed,
I will really appreciate that, 'cause it will make doing this project it a lot easier for me.

OK,

Here are some underside shots of the amp. Kind of messy, but it works very well. I hope you can see what I did. The power supply is at the upper right of the pictures. I just mounted two 1N5408 diodes right to the first cap section wired to the HV secondary of the transformer and then went to a ST-70 style choke. Then through a couple of resistors and caps and that's it. I believe the resistors are the same values as used in the original ST-70 - but they are new. Just to the left of the main power supply mounted on a terminal strip is the bias rectifier and filter for the fixed bias supply. It's a full wave bridge.





My intent is not to jack this thread, but the transformer in question is the Toroid of Maryland device. No problems at all and as I said earlier, it barely gets warm after running for hours in the amp.

Let me know if you have more questions. Wish I had made this a little more pretty. No hum and those output toroids make for a great amp. They are Amplimo units.

Regards,

Thank you very much, Ed.
Those pictures really help.
I'm new to this forum, but I got a lot of help already