Attenuators and tubes

Z

zepplin490

New member
I have heard a couple times, maybe on here or on the marshall forum that attenuators kill power tubes. I dont really know if this is true or no does anyone have any info either way. Im wondering if the v.p.r. on my TSL 100 head is the same as all of those external attenuators. I run most of the time with the vpr on so i can get some decent tones whitout blowing the windows out... Is it gonna F*ck with my Power Tubes?
-mp-
 
The purpose of an attenuator is to enable you to run your amp on '10' but then dial back the volume using the attenuator to bring the audible volume down to a more reasonable level. This is why they burn out power tubes faster. Take away the attenuator, and the logic re: power tube life still applies:

Run your amp on '2' all the time = power tubes have a longer life, as they are not being worked very hard

Run your amp cranked on '10' all the time = power tubes burn out faster, as they are being worked harder
 
I've found running an attenuator is not a problem unless (as was said) your running the amp dimed a lot. I know thats the intended purpose, but I use mine to find the spot where things are pumping, but not really dimed, then knock the volume down without stepping on it all the way. I've had good results with this over the years for whatever its worth ;)
 
Oh I dont dime the amp at any time, when ive got it running in 25 watt mode i run the volume at about noon and thats plenty for me, I would have the cops and angry neighbors as well as some serious hearing loss if the amp diddnt have the VPR...I run my gain on the lead channel at about 1 oclock and the gain on the crunch channel at about 2 oclock .. not that the preamp has any effect, But does it ? can the VPR of attenuation hurt more than just the power tubes?
-mp-
 
The problem with attenuators is multiple.

First of all, if you were playing the amp without one in a wide open space. You wouldn't have it dimed, just loud enough to sound good. But many with attenuators dime the amp way past the point they would ever go without one. The does put way more stress on the power tubes and they will wear and are more likely to fail sooner.

Also most attenuators are not matched to amps correctly. A 100 watt tube amp means 100 watts clean power (well most are rated this way) minimal power tube distortion. But when he amp is "dimed" to get that power tube distortion, you are beyond 100 watts. Not all attenuators are equal. And many can't handle that power, causing problems.

The ideas as someone else mentioned, find the sweet spot and use the attenuator to knock the volume down a few decibels.
 
I don't understand the mechanics behind it, but this is what I learned from talking briefly with Mr. Ho who designed the Ho attenuator (rebranded as ULTIMATE) which I use:

1. The 100 watt max load attenuator is sufficient for my 100 watt amp, but having 200 watt max load will help my tubes last longer.

2. You're probably not burning out your tubes that much faster unless you're pushing it past 2 o'clock all the time.
 
Enjolras56":2m4n8i8h said:
I don't understand the mechanics behind it, but this is what I learned from talking briefly with Mr. Ho who designed the Ho attenuator (rebranded as ULTIMATE) which I use:

1. The 100 watt max load attenuator is sufficient for my 100 watt amp, but having 200 watt max load will help my tubes last longer.

2. You're probably not burning out your tubes that much faster unless you're pushing it past 2 o'clock all the time.
Click to expand...


Actually that is one of the worst attenuators on the market. It reflects a 32 ohms back to the amp, which results in severe fly-back voltage spikes when the volume is up which break down the output transformer insulation in the windings and causes failures. Many amps have been destroyed but that attenuator. And it is not a real attenuator anyway, it is a load box that uses a solid state power amp to re-amp the attenuated signal to the amp.

Also referring to 2:00 on the volume control is a completely misguided statement (not you but the guy who told you this). It means absolutely nothing, many amps are designed differently, it all depends on the taper of the control, the voltage output of the preamp etc. In fact Michael Soldano (thank god) clarifies this in this video at 03:40, and he is dead on! https://youtu.be/-dLIGa84-qY On his SLO, 5 is about 11:30 and he is right. On that amp you are at 100 watts at Noon basically.
 
zepplin490":rkuz7usi said:
Oh I dont dime the amp at any time, when ive got it running in 25 watt mode i run the volume at about noon and thats plenty for me, I would have the cops and angry neighbors as well as some serious hearing loss if the amp diddnt have the VPR...I run my gain on the lead channel at about 1 oclock and the gain on the crunch channel at about 2 oclock .. not that the preamp has any effect, But does it ? can the VPR of attenuation hurt more than just the power tubes?
-mp-
Click to expand...
To my knowledge the preamp setting dosent matter much, but you can damage an output tranny in addition to output tubes with extreme settings (dimed with full attenuation) if the amp is run for extended periods like that (from what I've heard, but I'm an idiot) :LOL: :LOL:
There are people here who know much more about this stuff than I do. I just know I've had no problems at all running it the way I do, and I've had the same attenuator setup for 20+ years with no issues. Its an old Marshall SE100 that they havent made for years now.
 
This is what kills transformers, tubes etc...you never open an amp up like that with any attenuator, the idea is to set the amp up at gig or band practice volume then use the attenuator for bedroom, recording type of usage. Hell, on 2 most amps would blow the door off it's hinges.. :) :LOL: :LOL:


rlord1974":2k9wrok0 said:
The purpose of an attenuator is to enable you to run your amp on '10' but then dial back the volume using the attenuator to bring the audible volume down to a more reasonable level. This is why they burn out power tubes faster. Take away the attenuator, and the logic re: power tube life still applies:

Run your amp on '2' all the time = power tubes have a longer life, as they are not being worked very hard

Run your amp cranked on '10' all the time = power tubes burn out faster, as they are being worked harder
Click to expand...
 
JTyson":uhp4v6tl said:
I've found running an attenuator is not a problem unless (as was said) your running the amp dimed a lot. I know thats the intended purpose, but I use mine to find the spot where things are pumping, but not really dimed, then knock the volume down without stepping on it all the way. I've had good results with this over the years for whatever its worth ;)
Click to expand...

This is what I want one for. Take loud as hell down to kinda loud. Get the power tubes up to a sweat, and still enough going to get some speaker compression.

Any better brands, models?
 
baron55":1q9l1cee said:
Actually that is one of the worst attenuators on the market. It reflects a 32 ohms back to the amp, which results in severe fly-back voltage spikes when the volume is up which break down the output transformer insulation in the windings and causes failures. Many amps have been destroyed but that attenuator. And it is not a real attenuator anyway, it is a load box that uses a solid state power amp to re-amp the attenuated signal to the amp.
Click to expand...

Thanks for the input baron55. It has worked well for me (so far) and the reason I use it is for its dual volume footswitchable capability as I have a PPIMV amp (Marshall Vintage Modern) and I need a solution for a significant volume boost for solos. Obviously, I don't want my amps to be at risk. Do you have any reference threads so I can learn of other negative experiences? Didn't find too much with a quick Google search- mostly guys theorizing it's a bad thing.
Also, do you know of any other attenuators that you consider safe that provide the dual volume footswitchable capability? I believe the highly anticipated Friedman STFU will be able to, but do you know of any others?
 
The reason I say it is the worst, is because it reflects a very high impedance back to the amp which is bad. At low volumes without cranking the power section, you may get away with it.

The Gear page and Metro forums had tons of complaints many years ago when it first came out. Haven't heard much as late. From all the reviews, it sounds good, but the high impedance back to the amp was the big issue.

I don't have any personal experience with it, I know amp techs who have had blown tubes and bad trannies with users of this attenuator, whether or not it was the attenuator I can't verify.

What I can tell you with certainty is that cranking an amp full boar into a 32 ohm load is not good.
The other attenuators match the speaker cab load with the needed load for the amp.


I am not telling you to use it, but keep in mind what it is.

Here are some links.

https://www.thegearpage.net/board/showth ... p?t=522641

http://guitargear.org/2009/05/25/sorry- ... ttenuator/

http://www.marshallforum.com/marshall-a ... uator.html
 
baron55":1ypyp8j3 said:
The reason I say it is the worst, is because it reflects a very high impedance back to the amp which is bad. At low volumes without cranking the power section, you may get away with it.

The Gear page had tons of complaints many years ago when it first came out. Haven't heard much as late. From all the reviews, it sounds good, but the high impedance back to the amp was the big issue.
Click to expand...

Which attenuators do you feel are good or better?
 
I highly recommend the Alex attenuator, rivera rock crusher, ironman attenuator, or aracom attenuator.

I have only used the Alex, but all the ones I listed get mostly good reviews.

I have this masco ma50 amp, which is just pretty much unusable without the Alex attenuator. The volume knobs are very touchy.
 
If it is a normal attenuator & not a load / re-amp device- It is just a load on the amp ..... the same as a speaker. It will not wear out a amp or tubes any faster than if it was speakers with the same resistance. How you set up your amp definitely can wear tubes, etc - out faster.

I have been using one since the 70's....The last decade or so I have been using a THD Hot Plate.
 
Some amps I really like it a lot .... others I prefer the master on the amp. I do not crank my amps usually - I just set it up like I usually would blending preamp distortion with poweramp overdrive to get the sound I want & bump off a few dB's with the Hot Plate. I EQ my amp a little different when using the attenuator on different settings. Just small adjustments - usual bump up the lows & highs a little. Deep switch always on. I only use the Bright switch when on the -16dB's and then only sometimes. Some amps handle being cranked better than others. Also some people bias the tubes a little cooler if they crank the poweramp a lot. It changes the tone, feel and breakup a little. If you never run your poweramp hot you might like the bias set a little hot....
 
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