• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

6V6 line preamp

My Salas 6v6 pre. With Lundahl LL1660/25mA output transformers. Without SSHV2 still.

DC heaters via umbilical. Since I had no place inside left.
 

Attachments

  • salas_6v6_pre.jpg
    salas_6v6_pre.jpg
    114.3 KB · Views: 413
  • salas2.jpg
    salas2.jpg
    116.2 KB · Views: 400
Last edited:
Nice Bas. Ikea cutlery box? Whats your config and hows the sounds and measures?
Yep. Ikea cutlery box. Essentially the Salas 6v6 preamps standard. Without shunt reg. Sounds goods. I have never done any measurements on my amps. Because I don't have any facilities to test it with tools. Always use my ears as the final arbiter. Transforms my computer room gainclone by giving it a nice big bold tone. And sounds transparent with that big bottle tone in my main system.... if that means anything. I'll post some pics of the inside and some minor details that differ....simply because I had different stuff in my ports box. Solid state rectifiers with a damper tube after that...and elaborate snubber before the solid state rectifiers....small little chokes in the primary followed by a "standard" snubber..cap->resistor->cap.


Looks good Bas!
Thanks.

Did you compare it with cap out?
Also how did you wire ll1660?
Yes. I started off with cap input. Essentially it sounds pretty much the same. I mean the main character of the amp does not change really. But I did not want to worry about this cap or that cap anymore and I had no current use for my Lundahl's. Wired them up 4.5:1. In essence I moved to transformer output because I could. :) And I found that the background had less "noise" with the output transformer. Also I preferred the lesser gain of the transformer output.
 
Last edited:
diyAudio Chief Moderator
Joined 2002
Paid Member
because I could. :)

That line reminds the classic Nelsonian argument.:) Can't be wrong using stuff in hand when fitting the bill. I.e. giving proper gain and Zo for a given system in this case. Technically it can add the odd ringing on a square wave if not tuned with primary series resistor and RC across secondary. Cutting some bandwidth also. But to know exactly it takes a gen and CRO. Very nice wooden realization Bas, true diy. Congrats. :up:
 
Captain Ahab, a great battle awaits thee...

Captain Ahab had forgotten to throw the anchor:shhh:

Ripple was bcs ct was not grounded to mother earth.:p I usually let my poweramps tie both them and pre audioground to earth. Now all measurable ripple is gone, ie scope shows small microvolt noice but no waveforms. Some 10th of a volt slow fluctuation , but I dont think thats oscillation, just tempdrifts and normal linear PSU behaviour.

285 V at 2*38 mA current means that the SSHVS gonna eat 20ish and Im eding up at 260ish (ca 20+20 mA/rail) on the anodes for choke CF. Worth a try.
 
Damper tube? A diode? How does that work?
340230d1365003076-6v6-line-preamp-gm70bridgesupply.png


In series, i guess, it provides a nice slow turn on
Correct. Even though cathode stripping does not occur apparently when HT is present without the heaters being warm. I still like the slow ramp up.
 

Attachments

  • GM70bridgeSupply.png
    GM70bridgeSupply.png
    12.6 KB · Views: 651
Last edited:
Heloo

I putted some stuff together today to do some tests. Its a choke loaded cathode follower version with 110 H chokes. Its still ragedirag and I have some absent ground hum but it sounds decent.

I did some measurments and for compareness I took an old Rozenblitz Grounded Grid that I built long ago. 6V6 to the left and GG to the right.
10Hz, 20Hz, 50Hz, 100Hz, 1kHz, 5kHz, 10kHz and 20kHz. No wiggle at least:p
 

Attachments

  • 6V6 006 (3000x2000).jpg
    6V6 006 (3000x2000).jpg
    889.2 KB · Views: 378
  • 10kHz.png
    10kHz.png
    27.3 KB · Views: 100
  • 5kHz.png
    5kHz.png
    27.7 KB · Views: 105
  • 1kHz.png
    1kHz.png
    23.5 KB · Views: 100
  • 100Hz.png
    100Hz.png
    27.4 KB · Views: 102
  • 50Hz.png
    50Hz.png
    27.9 KB · Views: 95
  • 20Hz.png
    20Hz.png
    27.6 KB · Views: 350
  • 10Hz.png
    10Hz.png
    26.2 KB · Views: 369
  • 20kHz.png
    20kHz.png
    27.3 KB · Views: 108