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Power Attenuator........ any experience?


paulmcnamara
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When I had valve guitar amps, an attenuator was essential for home use, especially if the Master Volume was used to get that lovely power valve distortion.

You definitely don't need one if you're running a solid state or hybrid amp (valve front end). But if you're running a full valve rig, and want to use it at home, it's probably worthwhile investing in an attenuator.

It is worth bearing in mind though, that if you attenuate the output down, you also have to make sure that you have enough power to drive the speaker. Not enough power, and the speaker will "fart out" and sound awful. Too much, and your neighbours will be complaining.

I had a THD HotPlate, which at the time was possibly the only one around (ignoring the Marshall PowerBreak). They were rated in Ohms, so you had to have a corresponding HotPlate to your cab. Some of the modern attenuators have an impedance selector switch for connecting to a cab, select the right rating for your cab, and off you go (Instrument > amp > attenuator > cab).

There were complaints of attenuators not being "transparent" enough, but I always put it down to the guitarists either having cloth ears, or being cork sniffers. I never experienced any issues.

IMO, they're an essential piece of kit of you want to get your power valves glowing, but other than that, you should be fine without. Maybe invest in a smaller cab for home use (like a1x10 or something, instead of a 4x10).

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Great for guitars if you like the tone of overdriven power stage valves but aren't bothered about speaker break-up as part of your sound.

Less useful for bass for all the reasons given above, plus nearly all of them are only rated to be used with amps of 100W or under. 

I had the Marshall PowerBreak which I used with my 50W H&K guitar amp. Anything much more than mild distortion sounds would send the cooling fan into overdrive and kick out a good amount of heat. After a couple of hours of use at home playing volumes the casing would be almost too hot to touch. I wouldn't fancy using one with a typical high output bass amp. 

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I've been doing a bit of looking into this recently. As BigRedX says, the standard on the market are restricted to 100W. There's a few that hit 150W. I'm considering a standard Captor unit in order that I can use a low wattage amp at home silently and for recording, as well as using the head un-attenuated when the kids aren't asleep.

Twonotes is definitely worth a look in this area, as is Rivera. Not cheap though, and depends on your rating. Also as above I think it does wear valves down quicker, and whether it really delivers the tone you need at home is all personal preference IMO.

Equally, the Ampeg PF20 is worth looking at as a home practice amp for silent/ loud home practice. Doesn't need a load and can DI post power section. Twonotes also have some good power amp and cab simulations (I'm shedding one) if it's silent you're after with appropriate sims - and there's other great options out there. Just depends exactly what you're looking to achieve in my opinion, and then work out the most cost effective route to achieving what you want.

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20 hours ago, BassmanPaul said:

In my mind they are not such a good thing. You have to drive the snot out of your amp and then throw that power away as heat.  I feel you are going to be shortening the life of your amplifier.

Don't have to use them like that.

I just use mine to knock my mini JCM800 down a little for house use.

 

 

No use at all on solid state though, and I think I read somewhere that they can even damage some SS amps.

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1 hour ago, fretmeister said:

No use at all on solid state though, and I think I read somewhere that they can even damage some SS amps.

Don't see what they should. A properly designed speaker attenuator should present the same load to the amp as a speaker would. 

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2 hours ago, BigRedX said:

To the OP:

Can you let us know exactly which Fender amp you want to use the attenuator with? 

My use would primarily be with guitar rather than bass as my bass amp is solid state..........

Probably should have put thread in guitar dept. But it's been interesting to hear peoples experience and views on attenuators.  

The Fender amp in question is a Pro Junior (15watt) but pushing the valves at the right level is still far too loud for home use!

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42 minutes ago, paulmcnamara said:

My use would primarily be with guitar rather than bass as my bass amp is solid state..........

Probably should have put thread in guitar dept. But it's been interesting to hear peoples experience and views on attenuators.  

The Fender amp in question is a Pro Junior (15watt) but pushing the valves at the right level is still far too loud for home use!

In that case - Weber Mini Mass.

 

great little attenuator. I use mine on 50W guitar amps or under.

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17 hours ago, paulmcnamara said:

My use would primarily be with guitar rather than bass as my bass amp is solid state..........

Probably should have put thread in guitar dept. But it's been interesting to hear peoples experience and views on attenuators.  

The Fender amp in question is a Pro Junior (15watt) but pushing the valves at the right level is still far too loud for home use!

Just had a look at the amp in question and with no master volume control you are going to need one to get a decent overdriven sound at low volume. Also with an output of only 15W, pretty much any good quality power attenuator will be fine.

However bear in mind that some of the distortion tone might be caused by speaker break up which you won't get with an attenuator.

Also is the speaker in this combo attached to the amp section with a jack plug or hard-wired in? It isn't possible to see how it connects in any of the photos I found on line. If it is hard-wired you will need to cut the speaker cable and fit jack plugs to it in order to use an attenuator, and depending on much or little cable there is you might need to extend the leads too. Speaker cables tend to be as short as possible in combos. With the H&K Tube 50 the lead for the speaker which was on a jack plug only just reached to the PowerBrake when placed on top of the amp, and this was about 3" further away than where the speaker plugged into the amp.

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2 hours ago, BigRedX said:

Just had a look at the amp in question and with no master volume control you are going to need one to get a decent overdriven sound at low volume. Also with an output of only 15W, pretty much any good quality power attenuator will be fine.

However bear in mind that some of the distortion tone might be caused by speaker break up which you won't get with an attenuator.

Also is the speaker in this combo attached to the amp section with a jack plug or hard-wired in? It isn't possible to see how it connects in any of the photos I found on line. If it is hard-wired you will need to cut the speaker cable and fit jack plugs to it in order to use an attenuator, and depending on much or little cable there is you might need to extend the leads too. Speaker cables tend to be as short as possible in combos. With the H&K Tube 50 the lead for the speaker which was on a jack plug only just reached to the PowerBrake when placed on top of the amp, and this was about 3" further away than where the speaker plugged into the amp.

He'll need to cut it.

I had one once.

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On 09/06/2020 at 10:26, BigRedX said:

Just had a look at the amp in question and with no master volume control you are going to need one to get a decent overdriven sound at low volume. Also with an output of only 15W, pretty much any good quality power attenuator will be fine.

However bear in mind that some of the distortion tone might be caused by speaker break up which you won't get with an attenuator.

Also is the speaker in this combo attached to the amp section with a jack plug or hard-wired in? It isn't possible to see how it connects in any of the photos I found on line. If it is hard-wired you will need to cut the speaker cable and fit jack plugs to it in order to use an attenuator, and depending on much or little cable there is you might need to extend the leads too. Speaker cables tend to be as short as possible in combos. With the H&K Tube 50 the lead for the speaker which was on a jack plug only just reached to the PowerBrake when placed on top of the amp, and this was about 3" further away than where the speaker plugged into the amp.

It has an unplugable jack from amp to speaker, so can be done.

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21 hours ago, paulmcnamara said:

It has an unplugable jack from amp to speaker, so can be done.

Excellent! You'll just need a jack to jack speaker lead to connect the amp to the power attenuator input.

It will be at this point that you will find out just how much (or not) speaker break up contributes towards your preferred distortion sound.

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I bought one of these recently - very affordable and does the job nicely. 

https://www.thomann.de/gb/harley_benton_pa_100_power_attenuator.htm

Works great with my Ashdown CTM30 at home getting the back end to drive. 

I'll mainly be using it more as a dummy load box than an attenuator though so that when the CTM30 isn't loud enough for gigs I can just slave another amp off it.

IMG_20200519_214102.jpg

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On 08/06/2020 at 06:49, fretmeister said:

No use at all on solid state though, and I think I read somewhere that they can even damage some SS amps.

Yes, this is correct. Most class D power amps and all class AB/G/H amps that use bridged output stages are not ground referenced. When used with a load box or a DI (like the captor) at the speaker output, the minus terminal is connected to pin 1 audio ground which is connected to the power system's protective ground at the mixer. This effectively short circuits the minus half of the power amplifier and can cause major damage. It can also damage the mixer as the input ground network is not designed for such currents.

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On 13/06/2020 at 02:49, agedhorse said:

Yes, this is correct. Most class D power amps and all class AB/G/H amps that use bridged output stages are not ground referenced. When used with a load box or a DI (like the captor) at the speaker output, the minus terminal is connected to pin 1 audio ground which is connected to the power system's protective ground at the mixer. This effectively short circuits the minus half of the power amplifier and can cause major damage. It can also damage the mixer as the input ground network is not designed for such currents.

Is that only for bridged amps?

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12 hours ago, BigRedX said:

Is that only for bridged amps?

Yes, generally. Just be aware that many of the newer amps are in fact bridged, especially class D amps because there are some specific benefits to class d amps that do not apply to linear amps like class AB/G/H amps.

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TBH any modern solid state or Class D amp is going to be producing a far higher output then the average power attenuator is capable of handling, irrespective of whether it is bridged or not. The highest power handling I have seen on a power attenuator is 150W and the accepted practice is for safety it should be rated at twice that of the amp.

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13 hours ago, BigRedX said:

TBH any modern solid state or Class D amp is going to be producing a far higher output then the average power attenuator is capable of handling, irrespective of whether it is bridged or not. The highest power handling I have seen on a power attenuator is 150W and the accepted practice is for safety it should be rated at twice that of the amp.

With a power attenuator, this is true in most cases, but I was also addressing the use of a DI (with a speaker load) from a speaker output.

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On 08/06/2020 at 11:13, paulmcnamara said:

My use would primarily be with guitar rather than bass as my bass amp is solid state..........

Probably should have put thread in guitar dept. But it's been interesting to hear peoples experience and views on attenuators.  

The Fender amp in question is a Pro Junior (15watt) but pushing the valves at the right level is still far too loud for home use!

I have that 15w Pro Jr. as well paul ! It is louder than than I ever play my sterio. My Yamaha sterio amp has 85 watts RMS each side - the power of two Twin Reverbs !!

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