Marshall Power Brake Attenuator PB100 First Impression

[paul-e-mann]

Finally had a chance to try it out on my 1959, sounds great! No tone suck! I can play my amp at any volume and it sounds great! Several years back a member here I dont remember his name, said he owned 15 popular attenuators on the market and said the Power Brake was the best of the bunch. So I always remembered that and been on the look out for a good deal on one. Makes you wonder why Marshall doesnt still make them, then I answered my own question its cuz new Marshalls dont need them, Marshall is in business to sell new amps not accessories for old amps. Here's a glamour shot, I highly recommend it if you need one

 

[paul-e-mann]

A funny thing, I never knew how big and heavy these things were, when I got my eyes and hands on it I was really surprised lol!

 

[matttornado]

I been using them off and on since they came out in the mid 90s. They sound great in my opinion, especially with my 1974 100 watt Superlead.

 

[mark123]

How hot does it get when you're really cranking an amp into it?

 

[Gunner64]

Mine stays fairly cool, even when cranking. It's got a fan that uses the amps output power to power it.

 

[marshallmellowed]

Yes, I have a couple of them, and they both always stay fairly cool, barely warm when cranking a 100w amp. They use a unique design, where the cooling fan is powered by the signal flowing through the unit (fan spins as you play). There's also a one-wire mod that makes the unit sound even better (IMO), It basically shunts the electrolytic cap.

 

[Mitchell Pearrow]

Congrats on the power brake
@paul-e-mann

 

[JohnH]

Its great to hear about how well it sounds! PowerBrakes seemed to have been WAY ahead of their time, full reactive attenuation in small 3db steps and self powered fan plus impedance options. Seems they came out about 30 years ago? Here's a manual:

https://manualzz.com/doc/54223879/marshall-amplification-power-brake-handbook

and a schematic:

https://schematicheaven.net/marshallamps/powerbrake.pdf

Id guess it was a fairly expensive build, with a particular auto-transformer needed. It looks to have all the right parts to track a speaker impedance, though its hard to analyse due to the special parts that it has . Would be very interested to know how its tone sounds when you use it at moderate and then high attenuation. ( if interesred to try this, the best test is a looped riff recorded at full and attenuated levels, then normalised to equal volume)

 

[paul-e-mann]

How hot does it get when you're really cranking an amp into it?

Doesnt get hot at all

 

[playloud]

Its great to hear about how well it sounds! PowerBrakes seemed to have been WAY ahead of their time, full reactive attenuation in small 3db steps and self powered fan plus impedance options. Seems they came out about 30 years ago? Here's a manual:

https://manualzz.com/doc/54223879/marshall-amplification-power-brake-handbook

and a schematic:

https://schematicheaven.net/marshallamps/powerbrake.pdf

Id guess it was a fairly expensive build, with a particular auto-transformer needed. It looks to have all the right parts to track a speaker impedance, though its hard to analyse due to the special parts that it has . Would be very interested to know how its tone sounds when you use it at moderate and then high attenuation. ( if interesred to try this, the best test is a looped riff recorded at full and attenuated levels, then normalised to equal volume)

I agree - funny that the THD Hotplate (resistive load) was regarded as an "upgrade" in the early 2000s, but that's marketing for you!

I grabbed a PB over the xmas break for just under US$200. Initial impressions are very good. I may have been spoiled by my TAE, but it does seem a tad too bright at the more aggressive settings. I've ordered a 32R 25W resistor to bypass L1. Will be interesting to see if that makes a difference....

I've got all the gear to record such comparisons, so I may just do that in the next few days.

 

[JohnH]

hi @playloud , Ahead of testing it, I could totally believe that the 32Ohm across L1 may help control high treble with some amps. I arrived at the same place with similar values in my designs, (decades later!)

 

[marshallmellowed]

I agree - funny that the THD Hotplate (resistive load) was regarded as an "upgrade" in the early 2000s, but that's marketing for you!

I grabbed a PB over the xmas break for just under US$200. Initial impressions are very good. I may have been spoiled by my TAE, but it does seem a tad too bright at the more aggressive settings. I've ordered a 32R 25W resistor to bypass L1. Will be interesting to see if that makes a difference....

I've got all the gear to record such comparisons, so I may just do that in the next few days.

Interesting, I've never found the PB to be too bright, quite the opposite. As a matter of fact, the 1 wire mod rolls off some lows and keeps things tighter, which can be perceived as having more treble.

 

[Matthews Guitars]

I have one, in the uncommon white finish. It works great. I can't say it has NO tone suck, but it doesn't do a LOT of harm to the tone.

 

[playloud]

As promised, here's a comparison of all settings - from "Max" to -30dB (one click above "Min"):



Signal chain was: riff (in Logic) -> DIY reamp box -> 45/100 -> Powerbrake* (16 ohm setting) -> TAE (16 ohm, "100W") -> IR (my own IR of Pulsonic T1281 in cab below)

* Except in control.

Riff was recorded on Strat bridge pickup into Suhr Koko Boost into Neve DI (I wanted to see how much ghosting I could squeeze out of the 45/100 - quite a bit, it turns out!)

All clips were normalized to -13.7 LUFS (which ensured no clipping on any of the tracks).

And a wonky shot of pretty much everything used to conduct the experiment:

 

[AndyD]

As promised, here's a comparison of all settings - from "Max" to -30dB (one click above "Min"):



Signal chain was: riff (in Logic) -> DIY reamp box -> 45/100 -> Powerbrake* (16 ohm setting) -> TAE (16 ohm, "100W") -> IR (my own IR of Pulsonic T1281 in cab below)

* Except in control.

Riff was recorded on Strat bridge pickup into Suhr Koko Boost into Neve DI (I wanted to see how much ghosting I could squeeze out of the 45/100 - quite a bit, it turns out!)

All clips were normalized to -13.7 LUFS (which ensured no clipping on any of the tracks).

And a wonky shot of pretty much everything used to conduct the experiment:

Thanks for doing this! I listened with headphones and couldn’t hear too much difference. I have one myself and only use it at -6db. It sounds great to me!

 

[playloud]

Thanks for doing this! I listened with headphones and couldn’t hear too much difference. I have one myself and only use it at -6db. It sounds great to me!

It's subtle, but you can definitely hear the bass dropping out (or increased treble, at least relatively speaking) as the attenuation progresses. Easiest way to hear this is comparing control to -30dB directly.

Might plot some frequency distributions tomorrow to confirm my aural impressions.

 

[AndyD]

It's subtle, but you can definitely hear the bass dropping out (or increased treble, at least relatively speaking) as the attenuation progresses. Easiest way to hear this is comparing control to -30dB directly.

Might plot some frequency distributions tomorrow to confirm my aural impressions.

You are absolutely right, of course. In general terms, I tend to go by the “less is best” rule, particularly with attenuation. I like my power brake. It does what I need it to do, well. 🙂

 

[purpleplexi]

Hhhmph. I was suckered into buying a hotplate instead of one of these a long time ago because the hotplate was said to be the thing. It wasn't and it's gone. At the time powerbrakes were dead cheap too.

 

[JohnH]

Thanks for that! they seem like great tests. will listen tomorrow on something better than my phone!

 

[paul-e-mann]

Hhhmph. I was suckered into buying a hotplate instead of one of these a long time ago because the hotplate was said to be the thing. It wasn't and it's gone. At the time powerbrakes were dead cheap too.

Took me awhile to get one cuz I never really needed it until a year ago when I got my 1959, at which point the PB100 was mega expensive. Took me a year to find one at $320 which is a little more than I wanted to pay but now I have it and I'll keep it. Better get one while they can still be gotten! My original plan was get a Bad Cat Unleash but now theyre all gone so I went with the PB100!