AmpRX Brownbox for vintage tube Amps

[Alfmonster]

Has anyone on here used the AmpRX Brownbox (https://www.amprx.net/product.html) with a vintage tube amplifier? It was originally made for voltage regulation for vintage guitar tube amps.

Also, does anyone know for certain if these things output Sine Waveforms or does it output square waveforms? I can’t seem to find out any information on this.

I would looking to hook up a McIntosh MC225 to this - and if it allows in the second outlet, a MX110z.

Another quick note is that I’ve been monitoring the voltage fluctuations for the last 5 hours or so using a Kill A Watt voltage meter and it seems to be fluctuating between 121.1 volts being the lowest and 123.5 being the highest.

 

[Selmerdave]

Looks interesting, not cheap at $350+ used and their "buy" link doesn't work, but for someone that doesn't want to go through the hassle of a bucking transformer perhaps it's a way to go.

 

[zackthedog]

Boy, that looks interesting. Thank for the post, it would solve a lot of issues with my various vintage amps. I will look into it.

ETA: The Backline looks even better for a pair of vintage monoblocks.

 

[Alfmonster]

Yeah the AmpRX website isn’t very user friendly - but it seemed to be an interesting option as a bucking transformer. I emailed them to see if they could tell me what waveform was being outputted.
There was a review on sweetwater where it seemed someone had a positive experience using this for their vintage stereo tube amp.

https://www.sweetwater.com/store/de...wnbox-tube-amplifier-input-voltage-attenuator

 

[Alfmonster]

Okay, so I just talked to the designer of the Brownbox at AmpRX and he told me that the output was a Sine waveform and not a square waveform. The max draw before fuses get blown is listed as 540w - although he says he would stay closer to 500.

I just ordered one from Sweetwater so I’ll see if it makes a difference in helping the 225/110z run a little cooler.