Old Heathkit tube amp

[yowza]

Hello all,

I have the opportunity to buy an old Heathkit tube amp (stereo?) probably cheaply but I haven't gotten down to details with the person who is selling it. He is not a musician or tube amp buff in any way, he just got a bunch of stuff from an old TV repair person including this amp and some tubes which I'm definitely getting.

I have no idea whether something like this might be usable to recycle and use to build a guitar amp or maybe just resurrect it as is.
Is this even worth thinking about as a project and what is a good reasonable price to offer? Including pics for you to see.

Thanks!

[Cliff Schecht]

I would buy that in a heartbeat.

[Cygnus X1]

I'd hit it!

[sliberty]

Chassis looks small but workable. The iron is probably very good. And you get tubes as well (old, but tubes never the less). Go formit ifnthe price is right.

[lumox0013]

these are all over flebay for about 50$ offer him 40$ I would take it for the Iron and the caps( test for leakage)cut a new chassis and make a killer 5E3. just my 2cents.

[Cliff Schecht]

The EIA code on the PT and general shape of the OT tell me that this thing is loaded with Stancor transformers. Probably an A-3311 on there which is a FANTASTIC transformer for 6V6's, especially in Fender builds. I feel like I'm letting a bit of a secret out of the bag..

[yowza]

The EIA code on the PT and general shape of the OT tell me that this thing is loaded with Stancor transformers. Probably an A-3311 on there which is a FANTASTIC transformer for 6V6's, especially in Fender builds. I feel like I'm letting a bit of a secret out of the bag..

Thanks Cliff for spilling the beans! I was hoping that someone here knew what the numbers on the PT meant.

Thanks to lumox also for giving me a ballpark $ figure.

This whole situation is very unique in that I met this fellow because he and his wife came to my house to look at and buy a pop up camper that my wife is selling. In the course of our conversation it came up that I was a musician and had been bitten by the amp building bug and he offered that he had this a bunch of tubes he had gotten from an old school TV repair guy. I gave him a list of tubes to look for and when he got back home he sent pictures of the Heathkit along with pictures of some of the tubes (see below). He has 4 GE 6V6s (not pictured) and the rest of the audio tubes are some RCA 12AU7s with a few AX7s, AT7s and AY7s thrown in. None are tested or matched etc so I will be taking a chance. The rest of them are TV tubes and I don't recognize many numbers. If these were all usable in guitar amps it would be quite a find! I'm going to go on Friday and look at what he has, there might be a few nuggets buried in that pile of used tubes too. They paid a deposit on the pop up and might want to barter for the balance they have left to pay. I might offer him $200 for the tubes and amp, does that sound reasonable?

Thanks for your input!!!

[Cliff Schecht]

$200 is waay too much IMO, most of tubes aren't so useful. I'd offer him $40 and would go up to $50-60 max depending on my budget. Sometimes buying mixed lots like this is a real PITA, especially when you can fill boxes with the useless tubes and can only tube up an amp or so with the useful ones.

[yowza]

OK well paying less money is even better! I'll offer up to $100 for the tubes and the amp. I'm only going to get the guitar/audio related tubes, I'm not going to buy all of them. I figure there might be a few more 12A_7 types buried in the boxes and who knows what else might be there.

Thanks this is very helpful!

[yowza]

The EIA code on the PT and general shape of the OT tell me that this thing is loaded with Stancor transformers. Probably an A-3311 on there which is a FANTASTIC transformer for 6V6's, especially in Fender builds. I feel like I'm letting a bit of a secret out of the bag..

I sure hope these transformers are still good as it sounds like the iron on this could make a nice Princeton style Fender which is on my short list to build. Thanks for the suggestion!

[rdjones]

I see 6AN8, so if you're cherry picking look for 7199, 6BM8, 6973, 6GW8, 6U8 which have been used in guitar and HiFi applications.
6CG7s ?

rd

[ampgeek]

5751's are very sweet tubes! ~75% of 12AX7 gain.
Black plates and 3 mica supports are the most desireable.

But....I agree with the consensus. Many tubes doesn't always translate into many useable tubes unfortunately.

Good luck,
Dave O.

[yowza]

The EIA code on the PT and general shape of the OT tell me that this thing is loaded with Stancor transformers. Probably an A-3311 on there which is a FANTASTIC transformer for 6V6's, especially in Fender builds. I feel like I'm letting a bit of a secret out of the bag..

OK Well the power transformer is a Stancor but it's a PC 8405 and the specs are in the picture below and it does look like I might be able to use it for a 6v6 build.

I'm having a harder time trying to find out info on the output transformer which is a 51-21 and it appears to be an Ultra Linear OT so I'm not sure I can figure out how to use that. The only info I can find about it was on a closed auction at vintagtetransformers.com
http://vintagetransformer.com/heathkit- ... ansformers

Here's an excerpt "This auction consists of two Model 54-25 power supply transformers and two Model 51-21 ultralinear output transformers, all removed from working amps. It is my understanding that these units were made by Chicago Transformer for Heath."

"These output transformers are well regarded for their extroadinary bandwidth, and surprising power handling capability, and are equally versatile in their suitability for use in many P/P circuits. Their primary impedance makes them ideal for use in mid power designs for a number of class A and class AB circuits using such common octal tubes as 6V6, 6L6, and earlier octals such as 6K6 resulting in ultra linear power of 10 to 15 watts per channel. These also work well in some P/P circuits using classic triode power tubes, by simply ignoring the screen taps used in ultra-linear operation. "

I can't find any specific info regarding the wiring taps so unless it follows some standard convention I'll have to resort to another way of figuring out the taps on this OT. Any suggestions?

Also I did get the tubes and along with the obvious guitar tubes that were in the picture I found in the bucket of tubes a bunch of what look to be new 12 AX7s including one Mullard, 4 or 5 Telefunkens and a handful of RCA's and GE so that was very cool. I also found more 12AT7s including Amperex, Raytheon, RCA and GE along with more 12 AU7s and 12 or more ABQ5A's which I've never used before. Nice haul!

If anyone has any more info on specs for this OT or info on how I can figure out the taps so I can hook it up, I would really appreciate it. I'd like to learn how to figure this out.
Thanks again!

[ampgeek]

Nice score on the tubes!!

Regarding UL OT, those taps can be wired to your power tube screens for reduced distortion operation. Used more often in HiFi plans than guitar amps. Some report that it makes for a too sterile tone. Others like it. Dealers choice!

http://en.wikipedia.org/wiki/Ultra-Linear

You could put an VAC signal on the OT primaries and measure the AC voltage on the secondary to calculate the UL tap %.

Cheers,
Dave O.

[yowza]

Regarding UL OT, those taps can be wired to your power tube screens for reduced distortion operation. Used more often in HiFi plans than guitar amps. Some report that it makes for a too sterile tone. Others like it. Dealers choice!

You could put an VAC signal on the OT primaries and measure the AC voltage on the secondary to calculate the UL tap %.

Cheers,
Dave O.

Dave,

Do you think it's possible to hook up the OT in a non Ultra linear way by ignoring the screen taps? I'll take the transformer out of the chassis soon and post shots because I can't find a diagram for the wiring so I have no idea which are the primaries or secondaries etc. Maybe the wiring colors follow some Stancor convention.

Thanks!