pete millet low mu preamp

[tubo]

hi,

has anyone built or heard this low mu preamp? does the circuit invert phase? i don't need to much gain in my amps that's why im interested in building this.any input please.thanks

Low-mu preamp

[dsavitsk]

Originally Posted by tubo

hi, has anyone built or heard this low mu preamp?

Yes to both.

Originally Posted by tubo

does the circuit invert phase?

Yes

Originally Posted by tubo

i don't need to much gain in my amps that's why im interested in building this.any input please.

The 6AS7 can be a very noisy tube. Look around for the 12B4 threads -- you can build much the same design with that tube, but it is quieter and more linear.

Yet another 12B4 line stage, or is the 12B4 better than the Grounded Grid.....

12B4 Line Stage Amp

[Tony]

the 6AS7 has a mu of about 2, it is an inverting type line amp.....

[Tony]

and the 12b4 can be microphonic...be warned....

[radiostar]

My friend made it with 6AS7, works fine for my ears ...


Good luck!

[tubo]

thanks guys,

i think ill just convert the 6v6line amp to cathode follower and see what happens.

[Jeffrey Davison]

Built one about a year and a half ago. Went with a single transfomer but dual power supplies, one for each channel. Went with a grid choke instead of a grid leak resistor. Geartz hybrid with the rectifiers. Need a touch of gain so went with a 421a. Just a little hum, but not intrusive enough to distract from the music. Just last week I went with DC on the 421a filament with a vccs rectifier/regulator. Also upgraded to Clarity Cap MR on the 10uf output caps, not that the Obligatos were bad, just want a bit more out of this piece. The pics were taken after I finished building it. Rectifier tubes are now a pair of EML 274B mesh plates and went with Shuguang Treasure series 6Ca7 as the old KT77's I had were a tad noisy as a CCS. Treasures were much quiter. VERY happy with the sonics.

JD

[radiostar]

Tidy job!

Congratulations!!!