A couple of Ebay amps about to expire

[skyboltone]

130170051088
http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... otohosting

The smaller chassis with the 5 tubes is the much vaunted AO-35. The EL-84s appear to be Hammond branded Amperex (holland). The OT is 8800 to 8 and the PT is 295-0-295 at about 150MA. What makes these PTs hot is that they have 250 ohm secondarys. They're soft as heck, meaning lots of sag without trying to create it. Carmen Ghia, Goodsell 17, Matchless Spitfire and Legend, and Trinity are all based on this PT. It's got a 6.3 and 5 volt filament winding.

The other amp is the reverb driver and uses a pair of EF-86s and a tube rectifier. It appears to be maybe missing one tube. I've never poked around in one so I can't tell you much about the transformers but Hammond always went pretty much by the book.

I got two AO-35s otherwise I'd maybe be bidding. I've seen them go for $100 or so but I paid less than $75 for each of mine + shipping.

If I'm stepping on one of you guys who are after these, let me know and I'll never do it again.

Dan H

[Buschman]

Do you happen to know the current capicity of the A0-35 6.3 winding. Will it hold up to el34s?

[muchxs]

Do you happen to know the current capicity of the A0-35 6.3 winding. Will it hold up to el34s?

I wouldn't push it. EL34s draw twice what the stock tube lineup uses.

[skyboltone]

Do you happen to know the current capicity of the A0-35 6.3 winding. Will it hold up to el34s?

I haven't tested it but I'd go along with muchxs. I'm building 1/2 a liverpool now to see what happens. You got to remember that this thing is made to SAG big time. I've made another twin EL-84 amp with one and though it's not finished (as far as I'm concerned) my kid won't give it back to finish it up.

What you could do though is add a filament transformer if you really wanted to try, but I think you'ld end up with a plate voltage of around 360. Wait just a minute and I'll simulate it and let you know.

Yes, just as I though. About 365V at idle and 352 when spanking it. It's a EL-84 or 6V6 kinda deal. And even then expect a floppy PS.

The transformer out of the AO-29 or AO-41 (2 6V6s and abuot 8 other tubes will do the job for the express though, if you use about 30V of zener at the center tap. I'll be putting one together in the next couple of weeks. Stay tuned.

[Buschman]

I used an A0-29 pt for my Dlite build & it worked great. I also built a 18lite into a A0-35 chassis on turret strips. It's lots of fun but I always wondered what a better OT would do for the amp.
The A0-35 pt is huge so I was curious about the current rating on the heaters. 350v is about what I had on the 18lite before I switched to a 5y3 rectifier.

[muchxs]

I used an A0-29 pt for my Dlite build & it worked great. I also built a 18lite into a A0-35 chassis on turret strips. It's lots of fun but I always wondered what a better OT would do for the amp.
The A0-35 pt is huge so I was curious about the current rating on the heaters. 350v is about what I had on the 18lite before I switched to a 5y3 rectifier.

If you want a honker of a PT try the transformer from the power supply from a Hammond PR40. I've seen vendors on the 'net advertise them as a "tube amp" although there isn't an amp on that chassis, it's just a power supply. The chassis is about the size of an AO-35, it's easy to identify as it has two 5U4G rectifiers. It's a good power supply for experiments because there's enough current available for anything your twisted imagination can come up with.

Having said that for the $50-$60 plus shipping these things cost you can buy a NEW Hammond Manufacturing PT. A 270HX or a 272HX gives you a documented 200 milliamps on the high voltage and 6 amps on the filaments. There's no guesswork involved, you'll have to screw up badly to melt one of those.