Benson - Vinny 1 Watt amp

[Phil_S]

...in reality, will be my only builds for a long while.. how many amps can one person build/own?

Obviously, you have no clue about reality. This is an addictive hobby. You might dial it back after you build 10 or 12. You might as well prepare yourself for the inevitable.

[unknowntome]

Can confirm some some numbers re power transformer thats referenced here:

https://guitar.com/features/opinion-ana ... ns-supply/

Contacted mercury to see if I could buy one direct however they only make them to order. Specs attached.

[unknowntome]

...in reality, will be my only builds for a long while.. how many amps can one person build/own?

Obviously, you have no clue about reality. This is an addictive hobby. You might dial it back after you build 10 or 12. You might as well prepare yourself for the inevitable.

Haha… it doesn’t take much to imagine that!

[Phil_S]

Yeah. I can't really help you with your pending addiction or with finding a power transformer. There must be a source in Australia or SE Asia for a 240V primary with 62.5-62.5 high voltage secondary and 6.3V filament windings. I don't think I'd go below 125V but anything above that will probably give you a decent result, just at more than 1W.

Unlike output transformers, power transformers are a relatively simple affair and fairly easy to make if you have the equipment and know how. If you were willing to pay what MM charges for their product, I'm thinking you can find someone in Oz to wind one for you. Just show them the 1-P drawing you posted and tell them how you are using it. They should know what to do.

Good luck.

[bodhi]

Yeah. I can't really help you with your pending addiction or with finding a power transformer. There must be a source in Australia or SE Asia for a 240V primary with 62.5-62.5 high voltage secondary and 6.3V filament windings. I don't think I'd go below 125V but anything above that will probably give you a decent result, just at more than 1W.

Unlike output transformers, power transformers are a relatively simple affair and fairly easy to make if you have the equipment and know how. If you were willing to pay what MM charges for their product, I'm thinking you can find someone in Oz to wind one for you. Just show them the 1-P drawing you posted and tell them how you are using it. They should know what to do.

Good luck.

... why would a 62.5-62.5 primary be meaningful in this case? the secondary voltages should be the same anyways no matter what the primary. Having had a quick look around I found a Hammond 369AX which is probably a bit pricey, but has multiple primary voltages with 125V and 6.5V secondaries.

[Phil_S]

Huh? I said 240V primary, 125V secondary.

[bodhi]

Yeah, realised my wires crossed there, sorry about that.

[Curlowe]

I’ve been on The Amp Garage pages for a while and haven’t made a post yet, the resources here are amazing as an aspiring builder. I wanted to build a 1w and thought this thread was great! I departed in materials a bit an meshed together a Rob Robinette micro idea and the layout posted here.

Attached is a layout I used

I used a 25k 8ohm output transformer and it worked, but since this is more about voltage numbers and maths after checking voltages (I’m an artist and woodworker and not an engineer) I calculated out that I should be using a 9.5k OT. Since the likelihood of finding that is null I’m going to try a 8k8ohm output, again these are by my calculations and they may be incorrect.

I’ll be happy to report back if anyone is interested

95E18676-994B-4749-8643-5D370460F47F.jpeg

I used a Antek power transformer

Thanks all

[johnnyreece]

Thanks for sharing! Don't know if you tried it or not, but if you use a 4 ohm speaker, that'll get you closer while you shop for OTs.

Edit: Come to think of it, an old 3.2 ohm radio speaker would get you pretty much spot on (it'd reflect something like 10k to the primary, which is pretty darn close for guitar work).

[Curlowe]

Thanks for the reply!

This stuff is still a bit outta my wheelhouse for sure… for clarification your saying for an better set up in this instance, hook up a 4ohm (ideal 3.2) speaker to the currently in use 25k 8ohm reverb transformer being used as an output transformer?

[johnnyreece]

Yep! If someone else wants to chime in to be sure my math is right, I'm sure that would be appreciated, too!

As an aside, and I'm not trying to make a sales pitch, but I have a ridiculous amount of speakers, if you want to go that route. No pressure!

[martin manning]

I would say 4k to 8k load, and lower the cathode resistor, 100 to 200 ohms. There will not be much head room with this low plate voltage.

[Curlowe]

Okay! Here is the update !!! This thing sounds amazing!!!!

The output is 5k 8ohm (amplified parts sells a ‘champ’ ot that has a 5k and 8k with a 4 and 8ohm)

It sounded best with a .02 or .01uf cap instead of the schematic .002uf cap

[TUBEDUDE]

Okay! Here is the update !!! This thing sounds amazing!!!!

The output is 5k 8ohm (amplified parts sells a ‘champ’ ot that has a 5k and 8k with a 4 and 8ohm)

It sounded best with a .02 or .01uf cap instead of the schematic .002uf cap

If you have the ability, audio clips are always welcome.