Amp RX Brown Box with MK VII

[Reiby]

Just picked up a Brown Box for use with Mark VII and Friedman Twin Sister
Using EL34’s in the MarkVII
Anyone have experience using a Brown Box with Mark 2C IV or VII? Trying 115V and 117v settings
Will this hurt the amp ?
My house current runs Between 121-122V

 

[bandit2013]

I doubt a reduction to 115VAC and 117VAC will pose any issues. US line voltage can range from 110VAC up to 125VAC so that falls in the standard range anyways. Just do not boost the voltage as there is an MOV that will crowbar and burn out if the input voltage is exceeded. Not sure on its trip point. It basically aids to remove any transients in the line but if the trip point voltage is sustained for any length of time, sparks will fly.

So with the two settings you mentioned, 117VAC is 2.5% reduction, and the 115 is 4.5% reduction. I highly doubt that would be any reason for concern.

EL34 power tubes in the Mark VII, since it lacks a Variac power mode like the Mark V90, that may be a useful tool for longer tube life (assumed) as that amp requires Variac power to be used with the EL34 tubes.

I am curious how you find the EL34s in the Mark VII. I never tried it with those skinny bottles yet.

 

[mace]

What does Variac mode on the Mark V run… 90V?

I am also curious about EL34s in the VII. Been having too much fun with the stock tubes to change it ip.