6V6 line preamp

[Bas Horneman]

I thought it worth it. Normally I would not but since this is a big power tube making it silent needed DC in my system.

 

[stevenrotterdam]

Danks Bas! I have the parts lying around, big schottky diodes from PC supplies and I wound a small choke so I'll get ahead with DC.

 

[Salas]

There is better harmonic noise measurable in FFT grass but not very critical. Though audible.

 

[Nihilist]

Forgive my ignorance, but is there a glossary of terms somehwere where I can look up the abbreviations you guys use ? I can follow through most of this stuff, but I don't know what a TVC is , or other such terms.

Any ideas where I can look this stuff up ?


Thanks, sorry for off post, just trying to understand the thread better .


......................Blake

 

[Salas]

FFT is Fast Fourier Transform, gives a full audio band picture, and TVC is Transformer Volume Control. I am not aware of some audio electronics jargon look up list, but you could google each unknown term as you meet it is one way.

 

[Nihilist]

Thanks. Some of them I know, some I can figure out based on what the topic is, but some leave me clueless.


.................Blake

 

[JimT]

What is the output resistance of this preamp?

Thanks
Jim

 

[Salas]

About 1500 Ohm when in gain mode, about 250 Ohm when in buffer mode.

 

[JimT]

A better search of this thread showed an impedance of 1.5k. Please correct me if I am wrong.

Thanks
Jim

 

[JimT]

Your very fast!!.

Thanks
Jim

 

[Salas]

Thanks
Jim

We possibly crossposted.🙂

 

[gtoro]

Hi folks , a question about a hum noise in buffer circuit with a simple crc+ 2last separate rc for each channel. I'm no surprise for litle noise with this kind of supply, but the noise go down a lot at maximum volume without and song is very clear the change of level...
Could somebody light me about?
Thanks a lot for any answer ...

 

[fdegrove]

Hi,

Not sure I understand but are you certain you have the volume control wired up correctly?

Ciao, 😉

 

[gtoro]

I think Was right i Can control level simpy the noise when the pot is in position without attenuation go down somebody db at my (not only) ear

 

[Salas]

The pot needs its body grounded also. Revisit the grounding scheme.

 

[gtoro]

The pot is an blue alpls, the cover is mainly in plastic i have to ground the upper side? I'll try this evening thanks a lot!
the sound it's very good! I'll try with SE EL34 and with a little T-amp and result was fantastic gain in deep, detail and "body" of sound..., I'm thinkng to separate in two cabinet pre and supply for give him in future the chance of better supply based on your circuit.

 

[Salas]

The Alps face plate is metal. It usually grounds when mounted to a zero referenced chassis. When not like that, use a collar and a ground wire.

 

[Salas]

P.S. About the sound congratulations. It will be even better when you will finish with all the build details. Better PSU is always a plus also. Post us some pictures when done.

 

[buzzforb]

Salas,
Time to rebuild the 6v6 preamp and I had a couple of questions. If I wanted to have balanced out, would it be smarter to use a unity gain phase splitter like the one found in the impasse, or a transformer? Would a standard 600: 600 transformer work on the output or would it cause issue? Lastly, have you had a chance to listen to the Amtrans Carbon Film?

 

[Salas]

Such Tx would load down the gain version's higher than 600R Zo. Better an active splitter, or step down 5k primary Tx instead of resistor anode load with balanced secondary. Given that your system gain allows 1:3 gain loss at the pre. Line noise will go down accordingly as microphony also nonetheless.

*No use of Amtrans yet. BTW they have given good feedback on it in the phono thread but they ultimately preferred the very low ppm foil and the non inductive ww very low ppm too. But in no power demanding locations.