#1
Hey guys, wondering if anyone can help me.

I've just bought a Marshall Valvestate 8008 Power Amp, running it into a Marshall 1936 2x12, but I'm having an issue with the volume, as it does not seem to be very loud!

I had a Peavey Vypyr 75w and it's nowhere near as loud as that was. I'm having to crank it to full volume at band practice and even then, its not really loud enough!

Has anybody else had this problem or have any ideas on what the problem might be?

Thanks,
Glenn
#2
sounds like something is deff wrong. I don't advise poking around inside unless you know what you are doing.
2002 PRS CE22
2013 G&L ASAT Deluxe
2009 Epiphone G-400 (SH-4)
Marshall JCM2000 DSL100
Krank 1980 Jr 20watt
Krank Rev 4x12 (eminence V12)
GFS Greenie/Digitech Bad Monkey
Morley Bad Horsie 2
MXR Smart Gate
#4
Marshall 8008 PA
AMT P1 Preamp Pedal
Boss NS2 Noise Suppressor
Boss ME-50 FX pedal
Various Guitars


The 'Input' level of the preamp pedal is on full whack too, which increases the sound, but only just!

Thanks
#5
Not sure what is happening but it is possible one of the fx is affecting the volume, try the P1 or Me-50 by themselves into the power amp (guitar->pedal->power amp), no noise gate, and see if there is any difference in volume. I am thinking that it is possible you're not getting the right level of input.
#6
Ok, I'll try that over the weekend as I haven't got any of my gear with me at the minute, but thanks for your responses!

I will post my findings on Sunday night (hopefully)!

Thanks again!
#7
Hi,

I checked with JUST my guitar plugged in and it's still very quiet!

The Power Amp is running at 4ohms but the cabinet is running at 16ohms. The Power Amp runs at 80w on each channel and the cab has 2 75w speakers.

Could any of this be part of the problem?

Thanks
#8
Quote by cleggems
Hi,

I checked with JUST my guitar plugged in and it's still very quiet!

The Power Amp is running at 4ohms but the cabinet is running at 16ohms. The Power Amp runs at 80w on each channel and the cab has 2 75w speakers.

Could any of this be part of the problem?

Thanks

Yes that is a problem run the cab and the amp at the same ohm setting. switch the amp to 16 ohms and then check it. It is an 80 watt amp, you are only getting 20ish watts the way it is running right now.
2002 PRS CE22
2013 G&L ASAT Deluxe
2009 Epiphone G-400 (SH-4)
Marshall JCM2000 DSL100
Krank 1980 Jr 20watt
Krank Rev 4x12 (eminence V12)
GFS Greenie/Digitech Bad Monkey
Morley Bad Horsie 2
MXR Smart Gate
#9
It is possible that you might have to rewire the speakers to 4 ohm. It is best to match the impedance but usually higher impedance on the speaker should not cause amp damage. Sounds to me like you have 2 speakers each at 8 ohm wired in series, so might need to be wired parallel but that's just a guess, you might have to open up and rewire.
#10
Thanks for your suggestions guys. I'll probably take it to a shop to have a look at, see what they can do!

Thanks again!
#11
Quote by cleggems
Thanks for your suggestions guys. I'll probably take it to a shop to have a look at, see what they can do!

Thanks again!

did switching the ohms make any audible difference at all?
2002 PRS CE22
2013 G&L ASAT Deluxe
2009 Epiphone G-400 (SH-4)
Marshall JCM2000 DSL100
Krank 1980 Jr 20watt
Krank Rev 4x12 (eminence V12)
GFS Greenie/Digitech Bad Monkey
Morley Bad Horsie 2
MXR Smart Gate
#12
First make sure you're not using a guitar chord to run from your amplifier output to your speaker cabinet. A guitar cord will have so much resistance that it will dissipate most of the output power as heat (I've seen them melt, short, and blow the amp).

Second, make sure that you're not running just one channel (it's a stereo amp with 80W per channel). If the amp is running in stereo, you should have one speaker per channel. Even then, each one of those speakers is a 16 ohm speaker, if I'm not mistaken. You would get much more power out of the amp if each speaker was an 8 ohm speaker and if each one of the two speakers was plugged in to one channel of the amp.

Here are the specs of a $329 1500W power amp to give you an idea of how much differently the power gets applied depending on how you're wired up and what your speaker impedances are:

1 CHANNEL RMS continuous
- 8 ohms: 300 watts
- 4 ohms: 500 watts
- 2 ohms: 800 watts
BOTH CH RMS continuous
- 8 ohms: 210/210 watts
- 4 ohms: 400/400 watts
- 2 ohms: 700/700 watts
BRIDGED RMS continuous
- 8 ohms bridged: 800 watts
- 4 ohms bridged: 1400 watts

As you can see, the range is from 300W total output to 1400W output in this case.
Last edited by dspellman at Jul 29, 2013,
#13
Looking at this:
http://medias.audiofanzine.com/images/thumbs3/marshall-8008-1991-1996-397293.jpg
There is also a "linear" option - any change if you flip that over? I am thinking each channel has a preamp tube to warm things up, at least that is how it is on my VS head.

To further confuse the issue:
http://www.marshallforum.com/marshall-amps/32830-valvestate-8008-question.html

According to these guys the back means 4 ohms for both channels together so it should be self adjusting?

In that case you can do 8 ohm per channel, I think your speakers are 8 ohms each in a 2x12, so wire one speaker to left channel and one ot right and run it in stereo, apparently the amp wasn't designed to run in bridge mode so that means you're getting 80 watts per side but not sure if at 8 or 4 ohms. I'll check the manual just to be sure, but Marshall manuals from that era were quite confisuing

Pop out the cover and see if there are any tubes inside, the 12ax7s might be old and that could also be choking the signal. That's why I thought "linear" would take the tubes out of the equation.
#15
Looks like the speaker load on both shouldn't exceed 4 ohms so that would mean 8 ohm per side max.

Not sure if the "valve" in this one means preamp tubes or mosfet tech, couldn't find mention of preamp tubes in the manual but it wouldn't hurt to see just in case it has them, they could be ancient and need changing.

Either way looking at it 80 watts on the Valvestate wasn't really that much so you should try to run both sides.
#16
Let's just clear up some of this BS.
The minimum impedance is 4 ohm, not maximum. If you are running twice the impedance speaker you will be getting a drop of about 3dB, give or take.
The Valve in a Valvestate is in the preamp. Valvestate is a model, not a statement of what's inside per se. Your power amp is the power amp from that range, it doesn't have a tube IIRC.

There could be a few things causing your problem. It could be dirty/dodgey jacks, it could be a faulty transistor or some other device.
The first thing to try is cleaning all the jacks. Buy a can of electrical contact cleaner. Deoxit is a good one but any will do (NOT WD40, proper contact cleaner). Spray some liberally onto a plug and work it in and out of the sockets a few times. ie use the plug as an applicator.

If that doesn't work then it's time to go to a tech. It may need a socket replaced or a transistor. Power transistors do wear out, don't fall for the myth that SS amps don't wear out - they do.
Gilchrist custom
Yamaha SBG500
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Randall RM100 & RM20
Marshall JTM45 clone
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Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#17
Quote by Robbgnarly
did switching the ohms make any audible difference at all?



Unfortunately there is no way of switching the Ohms on either the PA or the Speakers (there aren't any switches or knobs on either to do so simply). It looks like I'll probably have to take it to a tech to have a look at. Could be any number of different things!

Thanks for your input though, every piece of advice is warmly welcomed!
#18
I don't care if this is an old thread - I'm resusrrecting it due to stumbling upon some ******ed answers.

Sorry to burst everyones crazy theories. Someone has already touched on the answer already here.

Cleggems has a 16 ohm cab. His amp can take 8 ohm mono or else 4 ohm in both the left and right outputs.

So if he is running his 16ohm cab in an amp that needs 8ohm mono to run at full volume or 4ohm stereo in left and right channels to maximize the amp output then he is gonna get severly reduced volume.

His cab does not have a 4 ohmn option, so only 16ohm so he will never get any decent out put from his amp with a ohm rating of 16ohm. The problem is not the amp, and the thing he needs from the music shop is more compatible cabinets. I hope he didnt waste his time getting ripped off by a tech to tell him his amp is fine!!

options for 8008 are

4ohm per channel in stereo mode
8 ohm in mono mode

(that's 4 ohms each for all those who think it means 8ohm both channels to make a sum load of 4)


please observe the "per channel"

issue - the cabinet he's using is 16ohms = f++k all volume output

NEW WAVE OF BRITSH HEAVY METAL!!!!
#20
Even into a 16 ohm cab it's just a 5 to 6 dB drop, that aint a lot really. This sounds more like a fault condition to me.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#21
I have an 8008 and suspect the problem could be preamp signal level. I first bought it about 20 years ago to run a multi FX unit through it into a pair of 8ohm speakers. Same problem of very low output. I kept it but didn't use it for years. I then started using this as a second power amp for a stereo setup running gtr-pedalboard-Diezel Einstein 50W head-TC Gmajor in the serial loop with one return to the amp FX return and the second going to the Marshall 8008 feeding an 8ohm cab. No probs with volume and sounds lovely and clear. I also used the 8008 with a Pod XT live and again no problems with volume limitations. I'm not familiar with the preamp pedal being used but this amp needs quite a hot preamp signal to sing in my experience.
#22
Don't necrobump. Start a new thread, and we will help you out.
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