Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: kagliostro on May 27, 2016, 09:46:25 am

Title: Output 1:1 transformer - Which one for this circuit ?
Post by: kagliostro on May 27, 2016, 09:46:25 am

This is the circuit on which the transformer is to be used

(http://i.imgur.com/cVoQnlb.jpg)

I've find this two options

10K:10K
http://www.tube-town.net/ttstore/Transformer/Matching-Transformer/Xicon-42TM018-1-1::2373.html (http://www.tube-town.net/ttstore/Transformer/Matching-Transformer/Xicon-42TM018-1-1::2373.html)

600R:600R+300R
http://www.tube-town.net/ttstore/Transformer/Matching-Transformer/Audio-transformer-1-1-2-1-for-line-signals-LTR-110::3813.html (http://www.tube-town.net/ttstore/Transformer/Matching-Transformer/Audio-transformer-1-1-2-1-for-line-signals-LTR-110::3813.html)

Which one is the best choice ?

Thanks

Franco

Title: Re: Output 1:1 transformer - Which one for this circuit ?
Post by: labb on May 27, 2016, 11:44:01 am

try one of these     http://www.jensen-transformers.com/transformers/line-output/ (http://www.jensen-transformers.com/transformers/line-output/)

Title: Re: Output 1:1 transformer - Which one for this circuit ?
Post by: PRR on May 27, 2016, 03:34:21 pm

Is "M1" = 100K?

If so, the transformer drive is up to 50K source. The transformer primary should be that much.

Especially for bass, since bass response is the first to go when source Z is higher than transformer design Z.

Why 1:1 ? There is a LOT of gain. And it says "DI" which usually goes to a *microphone* input. That pot should be 1V out typical, mike input needs a fraction of a volt. I'd think 5:1 or 10:1 step-down.

Possibly a tube mike input transformer used backward.

If there is any hope of a 15V-35V DC supply (heaters?) I would sneak in a chip to drive the long line.

Title: Re: Output 1:1 transformer - Which one for this circuit ?
Post by: kagliostro on May 27, 2016, 04:05:16 pm

Thanks labb & PRR

Quote

I'd think 5:1 or 10:1 step-down.

so ... this will do the job ?

10:1
http://www.tube-town.net/ttstore/Transformer/Matching-Transformer/Audio-transformer-10-1-for-microphone-signals-DIB-110::3812.html (http://www.tube-town.net/ttstore/Transformer/Matching-Transformer/Audio-transformer-10-1-for-microphone-signals-DIB-110::3812.html)

Franco