Gain during power amplification and Master Volume

Hasie

I'm a bit of a newb and doing research regarding tube amps <= 20 Watt.

Everywhere I read, people say you should not turn the pre-amp gain too high and rather get gain from the power amplification stage, because it sounds better, you get less noise, etc.

Now what I can't find info about is the following:
If the amp has a gain knob(pre-amp), a volume knob and a master volume knob: When turning the volume knob high and the master volume low(in an attempt not to make the whole family deaf), will I still get power amplification stage gain or not?

Basically what I want is:
A small tube amp, where I can get power stage amplification at low volumes, preferably with two channels and a footswitch and an effects loop.
I'm looking at the Blackstar HT-20, but I am not sure if I will be able to get power stage amplification at low volumes.

ezietsman

This is the age old question all tube lovers ask.

Simply put, there is no real way to get the full effect at low volumes. Deal with it.

However, there are ways to get closer to that sound.

1. Get a smaller amp. 20 Watt sounds like not a lot but it really is. 5 watt amps are still much too loud to crank at any time you want to. The rule of thumb for loud TV volumes is 1/4 Watt *

* 1/4 Watt amps suck. The nicest sounding valve amps are of the push-pull power stage variety (most amps over 10 watt are this kind). Your best bang for buck is around 15-20watt.

2. Use a power attuenuator. This is a device that goes between the amp and the speaker. It basically absorbs some of the power that would have gone to the speakers, making the amp less loud. These work fine unless you are trying to get the amp to be super quiet (night playing), then they start sucking too. Too little power to the speakers and it starts to sound thin again.

3. Variable voltage regulators. These are circuits you install into the amp circuitry. They effectively reduce the amount of headroom each amplification stage has and hence drops the volume when the amp starts overdriving. Too much of this also makes the amp suck, but this is my favourite route. Both amps I have built have these things in them (my other amp is a 5 watt)

4. Post Phase-Inverter Master Volume (PPIMV). Another circuit modification. It is a master volume that is installed before the power tubes. This is basically the same as the Master Volume on amps that has them, usually used on amps that don't have them. They reduce volume but also power tube distortion. Some people like them and some don't. If your amp has a master volume you dont need this one.

5. Install less efficient speakers. 102dB speakers are LOUD. 100dB speakers are LOUD. 97dB speakers are loud and 90dB speakers are probably not so loud.

Some amps come with VVR installed from the start. They may call them different things. Easiest thing to do is to buy an amp you like and get an attenuator. Keep in mind that not all amps are actually meant to be cranked to the point where the power tubes will overdrive, Ibanez TS-10 comes to mind, that amp won't overdrive its power tubes at all. My Blackstar HT5 does, in a limited fashion. The HT 20 will too but is incredibly loud when you try that. You probably won't do it more than once in a while.

The real trick about these things is to see whether you like the sound of an amp and whether the amp responds by going clean / dirty by just turning the volume knob on the guitar. If it doesn't, look around some more (unless you don't care about that sort of thing). The whole point of power tube distortion is that you can more easily control it with the guitar's controls and your pick attack.

Hasie

Thank you. That was very informative.

I know there is the emulated output on the Blackstar HT-5R:
Can I take that output into another device with speakers and a volume control to control the volume and still get the overdrive?

There is another thing I can't find a clear answer on:
There are many people that say you should not just turn up the gain in the pre-amp for more overdrive(metal tone required), but keep it moderate and push the amp more using an overdrive pedal. They say it gives a great tone which is not over-saturated and bland.

What is the logic/reasoning behind this?

ezietsman

Hasie wrote: Thank you. That was very informative.

I know there is the emulated output on the Blackstar HT-5R:
Can I take that output into another device with speakers and a volume control to control the volume and still get the overdrive?

Yes. You can do this. I'm not entirely sure if the emulated output bypasses the power section or not. It may well skip it, in which case you won't get the same effect. I have a feeling it gets bypassed.

Hasie wrote: There is another thing I can't find a clear answer on:
There are many people that say you should not just turn up the gain in the pre-amp for more overdrive(metal tone required), but keep it moderate and push the amp more using an overdrive pedal. They say it gives a great tone which is not over-saturated and bland.

What is the logic/reasoning behind this?

There is a difference in the way the amp overdrives when you do this. If they mean that you put a strong (read loud, not more overdrive) signal into the amp, you may cause the first preamp valve to saturate and start overdriving, the rest of them will still operate normally. Turning the gain up causes one of the next stages to be overdriven. There could be a subtle difference between these sounds but it is definitely not clearly better one way or the other. Experimentation will tell you which you like better.

If you are after metal tonez, the Blackstars are really good at this. My HT5 (first generation without reverb) has loads of gain just from the amp itself. I've gigged it (not metal) without pedals and without using the footswitch. I controlled the dirtyness from the guitar (Les Paul). That worked just fine.

The nice thing about HT5 is that the speaker is not that efficient (in my older 10 inch model anyway) and added that it is 5 watt, you can play it cranked up even in your house without too much fuss. It is still loud but not quite as mad as a 15 watt amp with more efficient speakers would be.

Hasie

Thank you. Best then I take my guitar, go to the shop and try it on different setups. Now to find someone in PTA with Blackstar amps in stock to try on...

GuitarDoge

Also look at an orange tiny terror boosted with an OD pedal. It's 15 watts but has a built in attenuator to drop it to 7 watts. You could even look at my current main amp, an orange th30 which can be dropped from 30 to 15 to 7 watts and has massive amounts of good sounding preamp gain and you can drive the power amp at lower volumes.

psyx

Yeah the terror range is always a good idea! For metal you can go for the Jim Root or the Dark Terror. Both are very tasty amps with oodles of gain. The Jim Root can give you some nice low gain crunch and bluesy tones if handled with care.

And all terrors can do 15/7 watt, which is done by using only one EL84 or both