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modding valve amps?

D

dreadheadbass

Dec 17, 2007
881
20
england
#1
hey everyone got a quick question for you
i'm thinkin of getting myself a marshall superbass valve head but i've heard people say there not that loud which might be a problem for me as i play in a band with 2 guitarists with 100w valve heads and a drummer who likes the hard touch

i know you can mod amps with different valves and can add master volume controls and reverb effects etc but is it possible to mod the volume side of things?
 
#3
i_got_a_mohawk said:
I doubt you would be able to mod it to get a great deal more volume from it.
Click to expand...

this is what i've been thinkin but according to all the deadheads i've been speaking to you "just whack in some massive power valves and tweak the power" bear in mind that these are the same sort of people that think sticking a massive exhaust on a fiat punto makes it "50% more powerfull"
i knew it couldnt be that simple and it sounds like a deathtrap waiting to happen i think i'll leave it and save up for something with more watts rather than burning my house down with an electrical fire lol
 
#4
A reasonable rule of thumb I have followed is that if you take the power being used by your guitar player and multiply it by ten then that is the power a bass player needs to keep up. You need something like a 1000W and the speakers to handle that power.

There is no way to get more output out of a tube amp short of changing out the transformers and increasing the number of tubes in the output stage.

Paul
 
#5
dreadheadbass said:
this is what i've been thinkin but according to all the deadheads i've been speaking to you "just whack in some massive power valves and tweak the power" bear in mind that these are the same sort of people that think sticking a massive exhaust on a fiat punto makes it "50% more powerfull"
i knew it couldnt be that simple and it sounds like a deathtrap waiting to happen i think i'll leave it and save up for something with more watts rather than burning my house down with an electrical fire lol
Click to expand...

You would need to mod the amp.

But remember, if you double the power of the amp, it is only a 3dB boost.


I do disagree with the "needing 10 times" the power sentiment tho.

My band is me, two guitarists and a loud drummer. The guitarists are using 100 watt JCM900 half stacks, and im using a 300 watt SVT half stack. I win ;)
 
#6
Yes - the "needing 10 times" might apply to a solid state amp but as has been pointed out many times, tubes are a different kettle of fish. My guitarist uses a Hendrix reissue full stack while I use a Mesa 400+ and, to echo i got a mohawk, I win.
 
#7
dreadheadbass said:
this is what i've been thinkin but according to all the deadheads i've been speaking to you "just whack in some massive power valves and tweak the power" bear in mind that these are the same sort of people that think sticking a massive exhaust on a fiat punto makes it "50% more powerfull"
i knew it couldnt be that simple and it sounds like a deathtrap waiting to happen i think i'll leave it and save up for something with more watts rather than burning my house down with an electrical fire lol
Click to expand...

Trust me, I only wish it WAS that simple. A high power tube amp IS a death trap to people who know nothing about them and go poking around inside. I have been working on tube electronics since I was thirteen (a long time ago). I am restoring a '73 Hiwatt 200W tube amp and I am very very cautious about working on it.

If I may give you my advice - forget about a full tube amp. SS stereo power amps are so cheap that you can get a hugely powerful rig for very little outlay. Front it with a tube (Valve - I,m used to the North American terminology nowadays!) pre-amp and you can get a lot of the flavour of a full tube amp with a lot less weight. I can't recommend a make of power amp to you, I have lost track of what is available in the UK since my departure in '73. QSC seem to be popular on this site so perhaps you should take a look at those.

Paul
 
#9
Tim1 said:
Yes - the "needing 10 times" might apply to a solid state amp but as has been pointed out many times, tubes are a different kettle of fish. My guitarist uses a Hendrix reissue full stack while I use a Mesa 400+ and, to echo i got a mohawk, I win.
Click to expand...

Then you follow your advice and I will follow mine and good luck to us both.

Please let's not get into a tube watts / SS watts pile of hogwash and I'm prepared to bet I was playing through tube amps before you were even born and there was nothing fishy about any of them! :)

Paul
 
#15
thanks for the replies guys
i had a feeling the amp power couldnt be upped without serious modding but i thought i better check out the rumours
i think modding is right out of the window i know sod all about amps i can strip a bass down easy but amps i have no idea on

i'm dead set on an all valve amp i played through a hiwatt in the local music shop n i was instantly converted sure there heavy and the valves break if you sneeze near it and there mega expensive..... but the sound they make:bassist:

i've heard a couple of people throw the marshall VBA400 into the mix but i've heard bad reviews off so many people i'm not sure i wanna risk it
 
#16
Another solution is to get a more efficient enclosure.
Every time you double the number of speakers you will get + 3 db of boost.
This is the same as doubling the watts.

If you like the tube sound of the Marshall, remember that most of the sweet tube sound you hear, is
in mid tone and the higher part of the bass. If you added a solid state power amp on 200-400 watt
that can drive a 15" speaker up to around lets say 120hz (crossover) and the let the Marshall drive
a high efficient 4x10" cabinet.
 
#19
Tim1 said:
In response to Bassman Paul there was no intention to divert the thread into a tube/solid state hogwash. And be wary of making brash assumptions, my friend - I have been playing through tube amps for 43 years!!!!
Click to expand...

And I for forty six - building them for forty three. I owned a boutique hand made custom amp company before there were such things. However I owe y' one for the assumption, we old 'uns have got to stick together! All I meant was that I know more about tube amps than most players.

I still stick behind my original rule of thumb. While nothing is absolute, it has worked well for me over the years. I mostly use a 1000W Carvin DCM1000 to play through but if I am going "against" really loud guitar players I'll grab either a 1400W Mackie or my 1500W DCM1500 (and my ear plugs).

While I no longer build bass amps (I only do guitar amps now) tube pre-amps are a different matter. I do like to have a tube in the chain somewhere. I'm working on one at the moment and my backup rig contains a pre I based on the B15.

Paul
 

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