Purist 2 Line Amp

[kmtang]

I built this Purist 2 Line Amp but omitting the first stage. I thought I don't need too high the gain.

The details are in http://www.normankoren.com/Audio/Spice_preamp_2.html#Purist

The difference between this with similar circuitry is that the first stage employs local feedback to reduce the distortion.


Johnny

 

[kmtang]

By the way, I used 6SN7 instead of 12AU7.

 

[wa4swj]

Hi Jonny,

My first post to this forum - How does your line amp sound? I've been very impressed with Norm's analysis of tube circuits and was wondering how you like the circuit. One fine day I'd like to build a copy of his "TENA" power amplifier - if I can ever get time!

Regards,

Ed Long

 

[EC8010]

Welcome to the forum, Ed, I hope you enjoy it - you'll find the "Tubes" section quite busy.

 

[Timbo in Oz]

what AUthority do you have for the saturation on the Leak St 2O

was it in a published test, I doubt it was Haden Boardman.

First up the tests of the original way back by Hifi-News&RR, reported some 11 watts @ 20 Hz, and similar for the same OPT's on the 12 Plus.

And as stated in my post in response I measured 20 Hz @ 20 watts in pentode mode with just 1.5%D, with lower total feedback and a CCS on the different splitter tubes, I used 6CG7's. for this.

Further I have run the pentode chassis item into EBS 300 liter 15inch DC gold Tannoys, measured 20 hz sine waves at 98 decibels and b-all doubling. Okay?

As I said the bass limitaions in the Leaks in OEM form may have more to do with the PSU, I can't remember the model no. on my OPT's but there were several different iterations in the St20's life. I was told by the unofficial Leak site owner and writer of the recent book, that the ones I have are quite up to the job.

Timbo,

puzzled

 

[kmtang]

I still haven't check the waveform and frequency response of the line amp.

I have listened to it for couple days. It sounds pretty good to me. It's rather airy, open sound, fast.


Johnny