ECL84 TOS

[JBP]

Got the idea to try the TOS pre with the  SoLow ECL84 poweramp after reading tubnits comments on plugging his bluezmeister into the SoLow. This was quick and dirty to see if it was worth the time, energy, and exspense to invest in a real finished build. WOW !!! All kinds of tones out of this amp at reasonable volumes. The only thing I really messed with was the power rail. I used a 195-195 tranny and tried to keep the b+ up for D and E nodes. I only have an entry level understanding of how everything interacts in the power rail so here is what I came up with and comments/suggestions would be appreciated.  A 268v, B 255v, C 246v, D 241v, E 228v. Caps are 40,40,20,16,16. This is the direction I've been wanting/hoping to go in and I will build this into a finished amp.  Thanks for the great place to learn and participate, Jeff

[tubenit]

Is this what you did?   I am thinking you'll need a PT that will give you at least 160v on V1 plates to get the best tone?  Probably 185v or so on V1 would be even better.

You might make this work with a 275-0-275 PT and a 5Y3GT rectifier?

Problem is if you get a PT with too high voltages,  then is you're risking exceeding the voltages on the ECL84. However, that could easily be controlled using Dana Hall's VVR and set it so the LTPI and pentode ECL84 is still within maximum voltages while keeping the preamp higher volts.

 

With respect, Tubenit

[JBP]

OK , I referenced the attached TOS voltage chart and was able to come close with a little resistor tweaking. Here is what I came up with on my voltages -  5751 V1 pin1 143v, 12AY7 V2 pin 1 105v, 5879 pin8 106v. Does this seem reasonable  or am I missing somthing? Amp sounds darn good to my untrained ears. What do you think ?

[tubenit]

5751 V1 pin1 143v, 12AY7 V2 pin 1 105v

Keep in mind that 5751, and 12AY7 will give lower voltage readings than the 12AX7. My recommendation is that if the amp sounds great to you, then leave it alone or tweak slowly one mod at a time.

IF you have the amp opened up. Pop in 12AX7 tube strictly to take voltage readings (then replace your tubes back to the 5751 & 12AY7). If you are close to 160v with 12AX7's , then I think you're in a good range.

With respect, Tubenit