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SOHA II Builders Thread - Page 31

post #451 of 1688
Mouser is out of TL783 until March

Since I couldn't find an alternative with Mouser, I got one from Digi-Key. I saved a few bucks on the case by getting that from them as well. Of course I ordered some extra supplies that I can't get from Mouser, so I actually spent more

Is it just me, or did Digi-Key change it's minimum order policy? I thought they used to require a $50 minimum to avoid a handling fee. That no longer seems to be their policy.

Time to start tube hunting
post #452 of 1688
Quote:
Originally Posted by runeight View Post
My understanding (could be wrong) is that the Amveco transformers are rated before regulation and that they pull down below their spec'd values when full current is drawn. I read this, I think, on this thread.

Can anyone verify that this is correct or not? If it is true, then the amveco would not sub in this amp. And, obviously, if I'm wrong, we can put it into the BoM.
I believe Holland reported it is the ANTEK transformers that are rated unloaded (hence their 'enhanced affordability') I have an Amveco on my desk powering my M^3 - a quick measurement and I'll be back...
post #453 of 1688
18.97V and 19V on each leg under load for an 18V Dual Amveco 62064. These are nice transformers... I'd vote to add it, I believe we left it out originally for cost reasons. Shipping difference will more than compensate.
post #454 of 1688
When you order tubes, do you get more then 2 of a type?

I just ordered a bunch form vacuumtubes.net. I only got 2 each of 5 different models. Now I'm wondering if I shouldn't have ordered extras.

Anyway I ordered:
5963
6189
5814A
6922

He said 6922 are upgraded 6DJ8s and they were the most expensive at $25 each. Really nice guys though Too bad they were out of 8416's

I found someone selling them on eBay, so I might pick some up there.
post #455 of 1688
Just ordered a SOHA II kit from Jeff at glassjaraudio.com. What a nice guy. Since this is my first REAL project, I am sure I will be asking a lot of questions as I go. [At this point, I have only made a cmoy, guitar hp amp from a kit and modded my X-can (installed new caps/diodes).] I figure that this will be a real learning experience. Anyway, I hope I don't kill myself or catch anything on fire. It would be even better if the amp actually works and sounds good at some point in the future.
post #456 of 1688
Quote:
My understanding (could be wrong) is that the Amveco transformers are rated before regulation and that they pull down below their spec'd values when full current is drawn. I read this, I think, on this thread.

Can anyone verify that this is correct or not? If it is true, then the amveco would not sub in this amp. And, obviously, if I'm wrong, we can put it into the BoM.
I'd like to know this too, as I bought that Amveco in the original BOM. I have the rev1.1 board and haven't built the amp yet.

Quote:
Are we talking cognitive dissonance here?
No. It's the fact that we really do, to a large extent, judge books by their covers. A good chef knows that their food always tastes better when presented well, for example.
post #457 of 1688
I have finished my build and am running through the setup. I got to measuring the voltage of TB+ and got 124 volts, not 103 volts. Is this a problem and if so what are likely culprits?
post #458 of 1688
I just did a better search and saw that if none of the jumpers are jumpered that my high voltage is ok.
post #459 of 1688
Quote:
Originally Posted by lacrossebowe8 View Post
I just did a better search and saw that if none of the jumpers are jumpered that my high voltage is ok.
Strong work!
post #460 of 1688
I just checked the Amveco catalog - published ratings are under load, and include an unloaded voltage (higher than spec).

The 35 VA specs:

Part: 62073
Secondary Full Load: 2x15
Current mA:1166
No Load Voltage: 2x17.6

There's also a 50VA for the high current version:
Part:62083
Secondary Full Load: 2x15
Current mA:1666
No Load Voltage: 2x17.3
post #461 of 1688
Quote:
Originally Posted by Hayduke View Post
When you order tubes, do you get more then 2 of a type?
I usually order only (claimed!) tested tubes in pairs, mostly from flea-bay. As noted elsewhere in this thread, exact tube matching is not so critical with the design of this amp.

Quote:
Originally Posted by Hayduke View Post
Too bad they were out of 8416's

I found someone selling them on eBay, so I might pick some up there.
Sounds like a nice assortment to start rolling. I got Amperex 8416's here:

Vacuum Tubes, Inc. New Audio and Western Electric Tubes for Hi Fi and Guitar Amplifiers

But they were cheaper when I bought 'em!
post #462 of 1688
Thread Starter 
Quote:
Originally Posted by lacrossebowe8 View Post
I just did a better search and saw that if none of the jumpers are jumpered that my high voltage is ok.
And so, is everything else working ok too?
Dr. Cavalli gained notoriety with his first DIY amplifier projects. His success has blossomed into Cavalli Audio, a world leader in amplifier design.
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post #463 of 1688
Quote:
I just checked the Amveco catalog - published ratings are under load, and include an unloaded voltage (higher than spec).

The 35 VA specs:

Part: 62073
Secondary Full Load: 2x15
Current mA:1166
No Load Voltage: 2x17.6
Thanks for checking into that Wiatrob.

I picked up the Amveco from the original BOM - the 62063.
It is rated at 1.7A - is that going to be enough for the high voltage rev1.1?

EDIT - I see that this is 1.7A parallel and 25VA - do I have a problem then?
post #464 of 1688
I just finished everything and am listening to some music. Sounds good. I will post some impressions later. I am using sr-80's but usually use sr-225's and I am hoping to pick up some senn 650's soon. Pictures and more to come. Thanks for a great amp design.
post #465 of 1688
Thread Starter 
Quote:
Originally Posted by rds View Post
Thanks for checking into that Wiatrob.

I picked up the Amveco from the original BOM - the 62063.
It is rated at 1.7A - is that going to be enough for the high voltage rev1.1?

EDIT - I see that this is 1.7A parallel and 25VA - do I have a problem then?
You might have a problem with 850mA in series usage. But try it and see. We may ask for a few voltage measurements to check this. And these measurements are not available at the test points, but they mey measure the input voltages to the regulators. If these are too low the regulators will not regulate properly. If so, you may need to select an alternative trafo.
Dr. Cavalli gained notoriety with his first DIY amplifier projects. His success has blossomed into Cavalli Audio, a world leader in amplifier design.
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