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AA-100 output transformer power rating

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I have a buddy who is thinking about parting out his AA-100, since it has a blown PT, and the PCBs are deteriorating pretty bad. He offered me the Output Trannies for 80 bucks for the pair. I'm going over to check them with a multimeter sometime tomorrow.

I was thinking of using them in my upcoming 807 PP amp, but I'm a little concerned about them being undersized. The AA-100 was rated at 25 watts, and I know you want some magnetic headroom, particularly when using feedback.

I'm okay with cutting back on the power output. Given the 300V screen rating of the 807, I don't think triode mode is a good idea. My initial plans were to run 450 volts on the plate, with UL connection or a 300V screen supply depending on the transformers. I could realistically reduce the plate voltage to 410V without using a different PT. According to the datasheet, that should be an okay plate voltage for triode mode, though that's getting a little low on the power side. Thoughts?

So I suppose the real questions is how much I can realistically get out of those AA-100 transformers.

Sorry to spam y'all with more questions about my 807 design.:eek:
 
I have 3 pairs of these... 1 pair is in my amp with the baby huey boards and EL34's making around 25 watts in pentode. The other pair is in an amp with 25bg6gt's and makes around 18 watts in triode.

They are good quality trafo's and sound great!

I would not hesitate to recommend them;)
 
Best kept secret for pp triode connected pentodes. Damn there goes the steal prices on these
...

In this application they are a slight bit softer on the top vs hammonds but I can't say which is truly more accurate. I enjoy both options,
depending on my mood and the music at hand of course.
 
Also these are like 51-29 on steroids. Same size but about 1/2" to 3/4" thicker lam stack. Haven't tried them in an ea2/3 or ua1/2 type amp yet but I suspect these will bring it with that ubiquitos pent el84 design too esp
Given the high b+ Heathkit used on their el84 amps.

Have fun those are nice opts. Even if they don't work in in your application they exceed in many others. I've done it to 80ma on em with triode kt88 and they hold their own and then some.

Also these are like 51-29 on steroids. Same size but about 1/2" to 3/4" thicker lam stack. Haven't tried them in an ea2/3 or ua1/2 type amp yet but I suspect these will bring it with that ubiquitos pent el84 design too esp
Given the high b+ Heathkit used on their el84 amps. I love the Heathkit el84 circuit.

So have fun those are nice opts. Even if they don't work in in your application, you'll find they exceed in many others 15w or less for sure. I've done it to 80ma on em with triode kt88 and they hold their own and then some I'm home but like I said a bit polite on top though they don't measure weak up there. I think I am just used to the house hammond sound - a bit hot on top - and these are more refined I guess. Do they do have a bit of a peak around 18k but it's slight maybe 2-3db.

There's a pair of 51-58's on eBay now for a fair price...but they look a bit rustier than than the condition these are usually in and I've read that rusty lams can be problematic although I could be totally off base here. And they aren't that bad but I'm not sure I'd bid $100 on them given a better pair will be there soon.

The aa100 and varients are the end of Heathkit tube amps where they went to pcb so usually the opts are parted because those cheap kit-grade pcbs are too crusty to be sold on. They make the dynaco pcbs look like quality pieces.
 
Well first I've got to see whether or not they're cooked. The AA-100 my friend has is what most of us would describe as a "basketcase". He got it for basically nothing, and the poor thing looks like it's been used for just about everything other than amplifier duty.

I was thinking of using a Tektronix power transformer for this. Anybody got specs on the 120-141 or 120-037? I can find voltage specs, but I want to make sure I get something with enough current capability.

Also... I need an opinion. Those Tek transformers are pretty big. Like, 15 pounds big. Would those little AA-100 transformers look too silly next to one?
 
Update: So, I payed a visit to my friend, and we discovered that both OPTs were pretty well destroyed by water ingress- even the inner windings. I suspect that this was in a basement that flooded very badly at some point.

So, if I'd like to keep the cost under $150 per transformer, and I want those transformers a little sooner than when Edcor can deliver them, what would be your first choice? I emailed Transcendar, but they aren't taking orders.:(

I suspect that Electra-Print and Magnequest will both be a bit out of my budget.

Thoughts?
 
Here's my read of the Tek 120-037: 22W of copper loss plus a few watts of core loss would really be pushing it, unless there's forced air. But you wouldn't load ALL the windings and loss drops as square of the current. This would be loafing with a stereo KT88 amp.

As for outputs, get the Dynaclones if you can use the lower impedance. The 60W ones are $165, 35W are $130 ea.
 

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Here's my read of the Tek 120-037: 22W of copper loss plus a few watts of core loss would really be pushing it, unless there's forced air. But you wouldn't load ALL the windings and loss drops as square of the current. This would be loafing with a stereo KT88 amp.

That's pretty easily workable into a half decent power supply. Also, I really do need at least a 6K primary on the OPT, preferably a 7.5k, or even higher. Believe me, if I could use a dynaclone I would.
 
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Anyone used this before? I did some research, but was not very successful in finding much information about how it performs. It's a little smaller than I'd like at 35W, but I'm quickly learning that manufacturers think that wattage ratings are highly subjective. I'm very open to suggestions.
 
AA-100/AA-50 output transformers come up on the auction fairly often. Just a thought. I've gotten two nice pairs from there for reasonable prices. At least, less than buying new pairs. I also like Magnequest and have a couple pair of Mike's transformers and they are really good. The Dynaco reproductions are probably a great way to go as well.
John
 
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