Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Vil on July 10, 2022, 08:14:29 pm

Title: Schematic question
Post by: Vil on July 10, 2022, 08:14:29 pm
Question (probably dumb)about schematic of Valco 6161: There are two arrows labeled “A” coming off the signal path after the phase inverter. Anyone know what the heck they mean? All the other arrows are easy enough to figure out. I’m drawing a blank on the “A’s”. Thanx !
Title: Re: Schematic question
Post by: PRR on July 10, 2022, 10:16:05 pm
> I’m drawing a blank on the “A’s”.

I'm drawing a blank on "Valco 6161". I don't want to sprain my brain digging in my memory banks. Or wear out my Google. A hint or pointer would be nice.

However, is this the one where the "standby" shorts-out the push-pull drive to hush-up the amp for prayer moment?
Title: Re: Schematic question
Post by: isaac_teller on July 11, 2022, 12:44:15 am
file:///C:/Users/zafim/Downloads/valco_6161.pdf


https://manualmachine.com/valco/6161/5142259-schematic/

Title: Re: Schematic question
Post by: Latole on July 11, 2022, 03:50:40 am
It help if you show schematic or a link ;
Most of the time, these a letter mean they are wired to power supply.

Title: Re: Schematic question
Post by: shooter on July 11, 2022, 05:14:11 am
Quote
to hush-up the amp for prayer moment?
that's sorta what the circuit implies, were it's done is a mystery, looks like a Gibson draftsman error  :icon_biggrin:
Title: Re: Schematic question
Post by: HotBluePlates on July 11, 2022, 05:49:35 am
... Valco 6161: There are two arrows labeled “A” coming off the signal path after the phase inverter. Anyone know what the heck they mean? ...
https://manualmachine.com/valco/6161/5142259-schematic/ (https://manualmachine.com/valco/6161/5142259-schematic/)

One of the A's is "+ Signal," the other A is "- Signal."  + Signal plus - Signal equals "No Signal."

... "Valco 6161". ... is this the one where the "standby" shorts-out the push-pull drive to hush-up the amp for prayer moment?

What he said.  Apparently the "Standby" (not drawn) kills signal-drive to the power tubes to make the amp quiet.

Except the actual amp doesn't have a standby switch (https://reverb.com/item/7124558-1964-gretsch-6161-valco-chicago-supro-6973-tube-guitar-amplifer), so the feature was contemplated but not implemented.
Title: Re: Schematic question
Post by: dwinstonwood on July 11, 2022, 06:34:56 am
Except the actual amp doesn't have a standby switch (https://reverb.com/item/7124558-1964-gretsch-6161-valco-chicago-supro-6973-tube-guitar-amplifer), so the feature was contemplated but not implemented.

I think it's there on the 3-way switch; it's just hard to see in some photos.
Title: Re: Schematic question
Post by: sluckey on July 11, 2022, 09:45:18 am
The Valco 6161 schematic is in Hoffman's schematic library. I don't know why there are two "A" on the schematic. Due to the nature of the paraphase inverter, you can simply ground the top point A to totally mute the amp. No need to connect both point "A" together.