grimtraveller
If only for a moment.....
Could someone, in simple English, please explain what an attenuator or power brake is in regards to guitar amp ? What is it supposed to do ?
Track Rat
Just Your Average Sized Member
It goes between a tube amp and speaker. It attenuates the signal to the speaker, allowing you to drive the tube amp into distortion without all the volume.
guitarplayr82
Well-known member
Yep, it's very useful for non-master volume amps where the only way to get distortion is to turn it up until the power tubes start breaking up (which can be VERY loud depending on the wattage of the amp). The attenuator helps to get that breakup at lower volumes by "attenuating" some of the volume post-power stage.
E
ecc83
Well-known member
I prefer the term "power soak" for the devices that go between power amp output and speaker. The term attenuator means something specific to an electronics engineer and generally means a device of great precision that operates at millivolt signal levels.
There are BTW device on The Bay that purport to be "attenuators" but are in truth nothing more than a pot in a tin and you can make one for a few $$/££. These are connected into the FX loop of an amp and merely reduce the DRIVE TO THE POWER STAGES. They do not and cannot work the op valves harder. NEVER put such a device in a speaker line (in fact never put ANYTHING in a speaker line unless you are dead, bang sure of what you are doing!) The pot boxes can however be useful. Some amps have such a poor "law" on the master volume control that it is hard to set a convienient level. Useful too on non-master volume amps but there are surely few non MV models WITH FX loops?
It is said that power soaks will shorten power valve life. True, but only as much as if you were removing the windows with them down the Palaise every night! It IS true that a purely resistive load* is less kind to valves than the reactive speaker but then IMexp' valves fail due to voltage flashovers these days, not of old age and so resistive is marginally "safer". (Oh! and do not ever try a PS on a solid state amp!)
*There are transformer based soaks but theses are heavy and expensive and don't suit all amps soundwise (checkout a guy called ICBM over at musicradar.com He has tried most of the PS's with many amps).
BTW. For amps of 30W and less it is quite easy and cheap to make a power soak and is a good starter DIY project if you have a smattering of soldering and metal bashing skill.
Dave.
There are BTW device on The Bay that purport to be "attenuators" but are in truth nothing more than a pot in a tin and you can make one for a few $$/££. These are connected into the FX loop of an amp and merely reduce the DRIVE TO THE POWER STAGES. They do not and cannot work the op valves harder. NEVER put such a device in a speaker line (in fact never put ANYTHING in a speaker line unless you are dead, bang sure of what you are doing!) The pot boxes can however be useful. Some amps have such a poor "law" on the master volume control that it is hard to set a convienient level. Useful too on non-master volume amps but there are surely few non MV models WITH FX loops?
It is said that power soaks will shorten power valve life. True, but only as much as if you were removing the windows with them down the Palaise every night! It IS true that a purely resistive load* is less kind to valves than the reactive speaker but then IMexp' valves fail due to voltage flashovers these days, not of old age and so resistive is marginally "safer". (Oh! and do not ever try a PS on a solid state amp!)
*There are transformer based soaks but theses are heavy and expensive and don't suit all amps soundwise (checkout a guy called ICBM over at musicradar.com He has tried most of the PS's with many amps).
BTW. For amps of 30W and less it is quite easy and cheap to make a power soak and is a good starter DIY project if you have a smattering of soldering and metal bashing skill.
Dave.
aaronmcoleman
The truth is out there!
You have any links to the schematics and design for one of these simple "power soak" boxes? I've got an 18w amp I'd like to make one for, and I have a pretty decent small electronics background.
Thanks!
E
ecc83
Well-known member
Milnoque
Resident Curmudgeon
Attenuators can also be useful on tube amps with master volume. The master volume on most tube amps overdrives the preamp section. This is not as musical to many ears as overdriving the power section. My experience is that the tube life issue has more to do with attenuators allowing you to keep your amp cranked more of the time. The volume produced may be much lower but the tubes are working just as hard as if you were peeling the paint. Be advised, using an attenuator will have an effect on your frequency response (tone). It's not always for the worse. However, playing through a tube amp at low volumes can often leave you with unsatisfying tone. It's a tradeoff.
I much prefer the reactive type. YMMV
I much prefer the reactive type. YMMV
E
ecc83
Well-known member
The opinions on the sonic effects of soaks varies from "sucks tone" meaning HF loss to "thins the amp out" meaning LF loss! You would think both cannot be right but they can. Much depends it seems on the type of power soak, resistive or partly reactive and the amp. Some it seems suit one amp type better than others.
There is a guy, ICBM over at musicradar.com who has dabbled with most of the PSoaks on the market and a lot of amps. I generally respect his opinions.
Dave.
miroslav
Cosmic Cowboy
I have a few of the Weber MiniMass attenuators, 25W and 50W, and I've used them with a few of my amps. They do a good job. I also have a Kendrick unit which is purely resistive and doesn't have the speaker motor like the Webers do.
It also does a good job.
Initially, the amps sounded really good with the attenuators, but the longer I used them, I was not hearing the amps always how I wanted them. I dialed them in many ways, and I could always get them about 80% where I wanted them, but felt there was a certain "cloud" covering the tone and keeping me from that last 20%.
So one day a couple of months ago, I pulled the attenuator on one amp just for the hell of it, and there was my missing 20%. I then did the same on the other amps where I had them, and the same thing happened.
I just got use to the sound with the attenuators always in-line (even with the attenuator volumes dimed)...that I forgot how the amps could sound without them. With the Webers, even in bypass, the attenuator had some effect on the level and tone. I'm happier just recording louder (which I can do without issues in my studio) and without any attenuators, but I will still use them for some things. It wasn't all bad with them, and you can actually get another flavor of tones with them...but without them, the amp's certainly have even more life.
It also does a good job.
Initially, the amps sounded really good with the attenuators, but the longer I used them, I was not hearing the amps always how I wanted them. I dialed them in many ways, and I could always get them about 80% where I wanted them, but felt there was a certain "cloud" covering the tone and keeping me from that last 20%.
So one day a couple of months ago, I pulled the attenuator on one amp just for the hell of it, and there was my missing 20%. I then did the same on the other amps where I had them, and the same thing happened.
I just got use to the sound with the attenuators always in-line (even with the attenuator volumes dimed)...that I forgot how the amps could sound without them. With the Webers, even in bypass, the attenuator had some effect on the level and tone. I'm happier just recording louder (which I can do without issues in my studio) and without any attenuators, but I will still use them for some things. It wasn't all bad with them, and you can actually get another flavor of tones with them...but without them, the amp's certainly have even more life.