Valco Gretsch 6150 Voltages Question

[K Teacher]

Greetings,
Based on measurements from a Valco clone, I was able to estimate the circuit voltages (see below), assuming nominal component values.

If anyone have one of these in good working condition at hand or on the bench, could you please be kind enough to post the voltage values?

The voltage values I've seen on the schematics that are circulating in the web varies a lot and some do not even make sense…

Thanks in advance for your help.

VALCO GRETSCH 6150 SCHEMATIC with VOLTAGES

PS:

Plate_dissipation = (Plate_voltage – Cathode_voltage) x Plate_current
P_diss = (302 - 14.8) x 41.0 mA
P_diss = 11.8W (98% of 12.0W)

[PRR]

I don't see any obvious problem with the voltages you noted. It should play fine.

Are you asking someone to do a survey of "the schematics that are circulating in the web" and find the mistakes?

[K Teacher]

Hi PRR,

Thanks for your response.

No. I am not asking people to do a survey of the voltage values on the schematics in the web...

I am asking for real-world voltage measurements of the Valco Gretsch 6150 or other similar made by Valco to validate (or not) the estimated voltages... 

This info also may help someone else trying to repair one of those or building a clone...

[smackoj]

I was the owner of this model Valco amp several yrs ago. A great 5-8 watt amp but to reach it's full potential it needs a better horn than the smallish Jensen 8" alnico it came with. I built a couple clones because I loved the breakup sound it produced. I was new to amp building and I made quite a few mistakes so I collaborated with Mark Moser at frugalamps.com. I do not know which amp came first, the Fender Champ or the Valco (aka Supro, Gretsch, Airling, National, Oahu or Wards) 6150 so I do not know who pinched the design from whom, Leo Fender in California or Senor Dopera at Valco in Chicago? However the power transformer(s) and output transformer(s) in the marketplace for builders making an early Tweed Champ work just fine. If you use a similar pwr tx and output tx you should be very close to your target voltages.

[K Teacher]

Hi sluckey,

Reading the forums I got the impression you had a few of these little Valcos.

Anything to add here? … Thanks

[sluckey]

Never had any valco.

[smackoj]

Looking at Doug's parts store in 'Transformers' I see a Champ style output tx .02290
and the correct power tx listed as 125P1B


The original output tx used in the 6150 was small and wound for secondary at 3 ohms to match up with the 8" spkr


If you still have questions you could write to Mark at frugalamps.com he has lots of experience with this amp. Tell him Jack Bandito sent you

[K Teacher]

Hi sluckey and smackoj

Thanks for your input...

smackoj,

I went to this page:
https://hoffmanamps.com/MyStore/perlshop.cgi?action=template&thispage=Transformers&ORDER_ID=404760322

Clicked on transformers, and it loops back to the same page... what am I missing?

[sluckey]

Hoffman no longer sells transformers.

[K Teacher]

Ok, thanks sluckey...

[K Teacher]

Valco used to manufacture tube amps for a variety of brands, often using the same basic circuit design with some minor variations and different cabinets.

Couldn't find much about the Valco-Gretsch 6150, but I found several posts on the Valco-Supro S6606, which is the same 6150 amp plus additional pot and capacitor for tone control !!

Thank you all for your input…

[sluckey]

Gretsch 6150 schematic is in Hoffman's schematic library...

     https://el34world.com/charts/Schematics/files/Gretsch/Gretsch6150.pdf