Triad H.F. 10 Conversion

[lenniepickit]

Hi folks,

Kinda of a knoob posting here besides checking in for tweaks to my 18 watt and such.

Got this cool old amp from a from a friend and am wondering what the easiest conversion path would be here. I can see messing with what's there would be to much for my skills since I couldn't find a schematic and and I have no idea what a reactor is lol. So thought I'd see if anyone here had any ideas for a simple conversion. Maybe a drop in board using the transformers?

Here's some pics - tubes glow and there's no smoke coming out though all I get when plugged into it is this tone that will oscillate when I turn the treble knob!

Thanks!

[lenniepickit]

More pics...

[M Fowler]

Well when I was a farmer kid I would take amp finds like this and find the input convert to 1/4 guitar jack and then find the speaker connection and wire up a cheap test speaker and fire it up.

But now days we are more careful using bulb limiter or a variac when testing old amps, especially the variac to allow the caps to reform at low voltage.

[lenniepickit]

Doh! Forgot about the bulb limiter I made but did the jack hook up - that's when I got the hum/tone oscillation.


What I'm hoping to find out if anyone is familiar enough with this to tell me what kind of board might be a good drop in. Can I get and 18 or Tweed Deluxe out of it with those transformers or am I looking more at like a Princeton? Is that additional transformer and reactor the equivalent of a choke or something else I have no experience with? I've thought about one of the Superlite or Tweed Deluxe PCB's from over at guitaramppcb's - maybe that'd be an easy quick conversion path!?!?!

[Phil_S]

Many of your pictures are not focused making the markings difficult to read.

I think I see the power transformer is 700V @ 125mA. The voltage is too high for the traditional EL84 18W amp, but is about perfect for a 5E3 tweed Deluxe (6V6 amp) and 125mA is enough current capacity. You could also use it for a 6V6 based 18W build. I think I see 6.3V @ 4.5A and 5V @ 3A. That's plenty of filament supply.

I don't have any idea about the output transformer, but it looks plenty beefy. Is there a model number? What sort of tubes is this amp running now? Are the outputs labeled for impedance? Ideally, we'd figure out what it is and then we can decide if it is suitable.

That A-741 is probably something to put on eBay to fund the project. Don't expect big money for it, but you may get a few dollars for it. The old Triad transformers seem to fetch a premium.

I'm guessing there is a good Deluxe or 6V6-18W in this platform provided the iron is good. Actually, the 6V6-18W really begs for a modified JTM45 as a better choice, IMO, not that there's much difference. The main difference is the 18W is cathode biased and the JTM45 is fixed bias and has a presence control. I think the JTM45 has a more versatile tonal palette.

Nice find!

Edit: I'd like to add, if that was mine, I'd be inclined to gut it rather than attempt a conversion. IMO, there is no intrinsic value to the circuit that's there. Save the good stuff, including the caps if they aren't leaky. The electrolytic caps have to be discarded simply on account of age. You'll need to work with the existing holes and sockets. I think there's plenty of room to build a PTP or modified PTP 6V6 JTM45. When I say "modified PTP" I mean nothing says to be a purist. I might use terminal strips or maybe one or two smaller turret boards cut to fit to get it done. It will take some time to do a layout. I would not skip the layout work and this will be the most time consuming and brain stretching part of the project. Doing it on the fly is not likely to produce the best result.

[TUBEDUDE]

A reactor is an inductor. Commonly called a choke, especially when used as a ripple filter.

[Leo_Gnardo]

I agree with Phil S on the filter caps. The old ones are bad, which is why you get a lot of hum plus the whistle/howl tone. OTOH Triad iron is supposed to be high quality, so you got something mighty good right there. Now you just have to decide what to do with it. The JTM45-variant idea sounds right to me. Nice find!

[lenniepickit]

Very cool bunch of responses - thanks!

My camera sucks so I will try to get a closer look at the specs on the transformer. I really really dig the idea of just gutting the insides and doing a 6V6 JTM45 variant (JTM22? : ) so I'll post back with the info once I get a chance.

Thanks again for all the suggestions and info!

[Phil_S]

Back up some and it should focus better. I think maybe you are too close. If it has a macro setting use that to get in close. Good luck with the pictures.

We have the PT specs. Unless I stated them wrong (in which case you should correct me) we don't need another picture.

If you have a model number on the OT, we can probably look it up.

[M Fowler]

I would fix this amp and enjoy it. I doubt if all those coupling caps are bad and the filter cap maybe bad or just need to check the wiring thoroughly.

[JoeCon]

If you know the year it was built Triad has a catalog archive here:

http://www.triadtransformers.com/catalogHome.html

Check it out 50's and 60's catalogs.

[Structo]

Equalizing Reactor.

Pretty fancy name.

[Structo]

Equalizing Reactor.

Pretty fancy name.

[lenniepickit]

Alright - thanks for the Triad link - good stuff there - did a some snooping around there, got lucky and was able to easily find the info for the irons here. Unfortunately the res was a bit low but I'll tag the specs on below.. we're looking at the R14A and S14A there...

I guess the other parts are the ones I should post to ebay to fund this no?

Just to give ya'll a sense of where I am in build experience I did lots of mod work on several EVjR's - the crack that turned my into a tweaker. After that it was a Baby Will (which has also been modded and is now my main gigging rig : ) and then I did a Mojo Tweed Bassman which I really love (even through bass in the 1x12 combo I did it with a WGS CL-80 clone) but it is too loud for most of the stuff I do - which is why I love the idea idea of low watt JTM45

I figure for me the best route is probably a straight forward turret this time around - cause I do well with pics and diagrams lol - but I'm would know the how/where of calculating the differences that I'm assuming are in the back end of the circuit..

So where do we go from here!? : )

[Phil_S]

IMO, those transformers a more than perfect for 6V6's mated to a JTM45 design. This is high quality iron. I think you will like what you end up with.