Stand Alone Reverb Output Transformer

[jon]

I'm building a Premier 90 Reverb unit. The tank runs one 6AQ5 and one 6EU7 at low voltages (150VDC). I have multiple Single ended OT's I could use, a hammond 125CSE, a Champ OT etc. But I don't have a true stand aloe Reverb OT. Will using either of these transformers cause a problem or will I be fine.

[martin manning]

Schematic?

[didit]

Either will work. Hammond 125 has an advantage from multi-tap secondary. Both are a bit of overkill power-wise.

[jon]

Schematic?

Per Your Request. I'm just concerned as the CHamp OT is 5K to 4ohms. it will be mismatched with my 8ohm tank

[didit]

Champ transformer only has a fixed ratio. If you attach an 8 ohm tank then then you'll have nominal 10k ohm on the primary. FWIW the stock Fender reverb transformer is 22k8 ohm, but what Premier have spec'ed is mystery. That schematic has no notes on that.

[tubeswell]

As it happens, a 6K6 idling at just above 300V likes a 9k primary according to Tung Sol and GE, so 10k is in the ballpark.

http://scottbecker.net/tube/sheets/127/6/6K6GT.pdf

http://scottbecker.net/tube/sheets/093/6/6K6GT.pdf

[tubeswell]

And when I do this by calculating the Class A load resistance for an 8.5W tube at 300V:

Va/(Pa/Va) = 300V/(8.5W/300V) = 10,558R

[jon]

but the pv on the premier is 150'ish

[martin manning]

I would choose a load of 6 to 8k.

[didit]

I'd recommend using your 125 and not overthinking this. The working load from a reverb tank isn't going to tax that driver circuit. A 6AQ5 running below 150V is cruising. With the Hammond you can try a few different impedance options. The only notable changes will be in tone. Higher impedance should seem a bit brighter.

[matt h]

(deleted)

[Leo_Gnardo]

I'd... use whatever was cheapest and less likely to be useful in another build where the application matters more.

What Matt said ^^^ and I'd recommend the standard Fender reverb drive transformer plus don't sweat the math. Available from Antique/CE and several other sources.

What I've found is reverb tanks sound different one to the next, even from the same manufacturer, same model number. If you can get your hands an a batch of them, a dozen or so, try 'em all out with your Premier build and pick the one that pleases your ears the most. What I've found thru hours of frustration is you can't panel-beat a circuit into making a lousy tank sound good.

Also don't assume that only the large tanks can sound good. On occasion I've auditioned a number of tanks for a repair and settled on one of the small tanks. That it sounds good is what matters, I hope you agree.