Attenuators

fastonebaz

Can't you just place a volume pedal in the FX loop and have the pedal set so it's low volume?

m_c

fastonebaz said:

Can't you just place a volume pedal in the FX loop and have the pedal set so it's low volume?

You could, but you'll get a totally different tone.
If you're wanting to push either the pre-amp, or power sections of an amp, past the region of clean tones, then the only way is to ensure enough volume/power is being used to get into the distorted/overdriven region. Which means the only way to do that without the volume that goes with that, is to dump some of that energy into a attenuator, so it's not all going to the speaker.

By limiting the volume/signal going into the amp, it's essentially doing the same thing as turning the volume of the amp down.

Exorcist

I used a relatively inexpensive 'jettenuator' with my fuchs 'dumble style' amp and it was great. I was put off attenuators for years due to all the negative press, but wish I had bought one decades ago. Resistive worked for me, sounds great on my egnator too. IMHO

m_c

One of the problems, is human hearing isn't linear.

What may sound perfect at high volume, if you cut to exactly half volume, sounds like it's differently EQ'd. Combine that with the same also applying to speakers, you can have a noticeably different tone between high volume and low volume.
Which is why resistive attenuators are seen as being inferior. The fact you could just re EQ things, doesn't make for good marketing.
Re-active types, try to compensate for the change in frequency response at differing volumes, while the newer modern ones, are essentially doing the same, but using more digital/modelling technology.


Although I am amazed by how much gets charged for what is essentially a few power resistors, a couple switches, and some jacks mounted in a box.

merlin

Moving a large quantity of air does make things sound different and the body's response will of course be different. There is no substitute for that however, I use a RockCrusher by Rivera and it's a great tool. 

m_c

merlin said:

Moving a large quantity of air does make things sound different and the body's response will of course be different. There is no substitute for that however, I used a RockCrusher by Rivera and it's a great tool. 

That is however very true. A bass line isn't a bass line unless you can feel it!

jaymenon

  I have often wondered:
When you place a resistive attenuator between your amplifier and speaker, doesn’t the speaker still remain as a reactive load at the ultimate end of the signal chain? 

ICBM

Exorcist said:

I used a relatively inexpensive 'jettenuator' with my fuchs 'dumble style' amp and it was great. I was put off attenuators for years due to all the negative press, but wish I had bought one decades ago. Resistive worked for me, sounds great on my egnator too. IMHO

I think the negative press was mostly because people expected to take something like a Marshall Super Lead, set it how it sounds best at jet-engine volume, then simply turn the attenuator down to bedroom volume and expect it to sound the same but quiet.

That’s exactly the wrong way to use one and it won’t work - even assuming the attenuator is the right one for the amp. Usually it will sound horrible - fizzy, muddy, squashed, or a combination of all of them.

m_c said:

One of the problems, is human hearing isn't linear.

What may sound perfect at high volume, if you cut to exactly half volume, sounds like it's differently EQ'd. Combine that with the same also applying to speakers, you can have a noticeably different tone between high volume and low volume.
Which is why resistive attenuators are seen as being inferior. The fact you could just re EQ things, doesn't make for good marketing.

Exactly. If you use it as an extra overall master volume control, set it to roughly where you want first, and dial the amp in for that volume it works much better - and best of all (counterintuitively probably) with master volume amps where you can then balance the amount of attenuation to the amount of power stage drive.

A further problem is that at high attenuation, the attenuator's output resistance is very low - there is a low-value resistor in parallel with the speaker, which damps the speaker heavily and makes it sound 'dead', and is the main reason attenuators don't sound good at very high attenuation settings.

m_c said:

Although I am amazed by how much gets charged for what is essentially a few power resistors, a couple switches, and some jacks mounted in a box.

The resistive ones, yes - one well-known brand in particular...

Reactive ones are more expensive to make and can justify the price more. Although some reactive ones are less reactive than their marketing copy would seem to indicate.

jaymenon said:

  I have often wondered:
When you place a resistive attenuator between your amplifier and speaker, doesn’t the speaker still remain as a reactive load at the ultimate end of the signal chain? 

Yes, but the amp won't see it. Once the attenuator is set to more than 3dB down, the amp is seeing the attenuator as the bulk of the load, and once it's more than about 9dB down the speaker is more or less 'invisible' to the amp. This is the other main reason attenuators start to sound less good at higher attenuation.

This is actually quite useful because it means that if you match the attenuator to the amp (it's always this match which is important to get right) then you can use any speaker impedance you like, as long as you don't bypass the attenuator.

Fortheloveofguitar

Fryette PS2 all day long.  The best by far and I’ve used a lot 

ICBM

Fortheloveofguitar said:

Fryette PS2 all day long.  The best by far and I’ve used a lot 

It is good, but I wish people would stop recommending them - and other similar units - as "attenuators". They are not - they are dummy load/re-amp systems, which although they can serve the same purpose in some ways they are quite different in what they do, and are much more complex and expensive... probably unnecessarily so if you just want an attenuator.

For what it's worth I hope they've fixed the design and build quality issues from the first version as well, I worked on one and was not very impressed.

jaymenon

 So I can use an 8Ω speaker and 16Ω
 attenuator as long as I set my amplifier to 16Ω...?

ICBM

jaymenon said:

 So I can use an 8Ω speaker and 16Ω
 attenuator as long as I set my amplifier to 16Ω...?

Yes.

Actually you can anyway, especially if you're not cranking the amp right up - impedance matching is only important at high power, and in fact valve amps prefer a low mismatch to a high one (solid state are the other way round). Setting the attenuator to 16 ohms just makes it doubly safe.

jaymenon

...and by a ‘low mismatch’ you mean a higher impedance amp and a lower impedance speaker ...?   Just to be sure, it’s reasonably obvious, but I don’t want to blow anything up  :-))

ICBM

jaymenon said:

...and by a ‘low mismatch’ you mean a higher impedance amp and a lower impedance speaker ...?   Just to be sure, it’s reasonably obvious, but I don’t want to blow anything up  :-))

Yes - that way round is safe for a valve amp. Normally, a valve amp will safely handle any load between half and double the *matching* impedance - though there are exceptions - and if you have to choose, is safer with too low a load than too high.

A solid-state amp should not be used with any impedance below the *minimum* - usually, but not always, 4 ohms.

This difference is a big source of confusion.