amp help

[ric]

I have a marshall valvestate 8100 (1st gen) 100w. Plugged it in the other day and the od channel was non existent. I took it apart to find the valve had come out of its socket, I put it back in and fired her up again but the level is far lower than it should be (about a 3rd the level of the clean channel). Does this mean the valve needs replacing or do i have bigger problems?

[procopius]

That's odd. If your tube has a leak and lost its vacuum it ought to just bollocks it completely, not just bugger the gain (and that's the most likely failure mode for a tube that came out of its socket). I suppose a really slow leak through a tiny flaw in the glass might give you slowly decaying gain. Anything that could blow/damage the solidstate bits of the circuit ought to leave you with a very expensive paperweight, though, unless something seriously freaky happened.

So, at a wild guess, yes, you've got a buggered tube, but you want to take a look at that socket, it should have kept the tube properly seated. Did you drop it?

[ric]

It was delivered to me yesterday so its possible either the courier has dropped it or the guy i bought it off took it out for some reason, i dunno. I'm waiting to hear back. Luckily i didn't pay a great deal for the amp so if i have to spend a little to get it working properly then i don't mind.

[Fugazi]

I've had this issue before, with an 8080 (which has the same preamp circuit).

Replace the valve, should sort it.

[ric]

Yeah the 8080 is the combo version of the same amp, nice one Max, thats exactly the kind of comment I needed. Bloody expensive these valves though. Im glad theres only one to replace. I assume only the mullard valve is the one to go for? Its been suggested a slovek too but ive seen loads at varied prices and im a little confused, any suggestions?

[Rob Blundy]

What valve is it that you need?
I've a couple of Svetlana EL34's hanging around that you can have.

[Fugazi]

It's an ECC83 valve in there. Personally I'd go for a Sovtek, but that's just my opinion. You might get more warmth from a Mesa, but to be honest the influence of the valve on the sound in a Valvestate is all relative.

[procopius]

Yeah the 8080 is the combo version of the same amp, nice one Max, thats exactly the kind of comment I needed. Bloody expensive these valves though. Im glad theres only one to replace. I assume only the mullard valve is the one to go for? Its been suggested a slovek too but ive seen loads at varied prices and im a little confused, any suggestions?

As long as it's the right spec, it shouldn't make a difference. The warm tone is actually from the circuit design used (and, in older amps, the rather messy power supplies and pre-modern capacitors). As long as it's to the same spec the manufacturer used you'll get the same result - valve triodes work on some fairly basic physics so the real difference between brands is operating life.

[ric]

Fantastic. Thankyou. The big difference Ive noticed is price, the Mullards are about £30 - £100 on ebay where as the Sovtek are about £5.

Max did you have the specific cab for your amp? There is one cab custom built for this amp but I can find one anywhere and I don't really understand the ohm thing. Ive played guitar all my life but never really had or needed a decent amp, so please forgive my ignorance. Will any marshall cab work with this head?

this is what the manual says....

REAR PANEL (8100 only)
The rear panel features the mains input socket plus two parallel wired sockets for the connection of loudspeaker systems, the combined total impedance of which should not be less than 4 Ohms, eg; two 8 Ohms cabinets in parallel. The purpose built cabinet for the 8100 is the 140 Watt compact 4x12 model 8412.

[procopius]

Fantastic. Thankyou. The big difference Ive noticed is price, the Mullards are about £30 - £100 on ebay where as the Sovtek are about £5.

Some of that price differential might well be audiophiles driving the price up. These are the people who think that what direction you wire the cables between your cd player and speakers makes a difference, that manner of malarkey. They've been known to pay $500 for a fairly ordinary Cat6 cable with a direction arrow printed on it.

[ric]

Some of that price differential might well be audiophiles driving the price up. These are the people who think that what direction you wire the cables between your cd player and speakers makes a difference, that manner of malarkey. They've been known to pay $500 for a fairly ordinary Cat6 cable with a direction arrow printed on it.


Thats good to know, I proper panic'd last night when I searched through looking for these valves. Especially not really knowing what I was looking for and seeing prices going past £100. There are 2 slovtek ones about to finish on ebay at £3 for the pair. Chuffed.

[Fugazi]

Fantastic. Thankyou. The big difference Ive noticed is price, the Mullards are about £30 - £100 on ebay where as the Sovtek are about £5.

Max did you have the specific cab for your amp? There is one cab custom built for this amp but I can find one anywhere and I don't really understand the ohm thing. Ive played guitar all my life but never really had or needed a decent amp, so please forgive my ignorance. Will any marshall cab work with this head?

this is what the manual says....

REAR PANEL (8100 only)
The rear panel features the mains input socket plus two parallel wired sockets for the connection of loudspeaker systems, the combined total impedance of which should not be less than 4 Ohms, eg; two 8 Ohms cabinets in parallel. The purpose built cabinet for the 8100 is the 140 Watt compact 4x12 model 8412.

Any Marshall guitar 4x12 will work fine with this, it's a fairly standard configuration. My advice would be either a 1960a or a ModeIV, they're the best of the bunch in my opinion. You can pick up a 2nd hand 1960a on the net for around 200 notes.

[ric]

Excellent. Thankyou, all of you. Hopefully by the end of the weekend my amp should be sorted. Now all I need to do is get the Guitar rewired so I can play the damn thing.

[Fugazi]

Excellent. Thankyou, all of you. Hopefully by the end of the weekend my amp should be sorted. Now all I need to do is get the Guitar rewired so I can play the damn thing.

Anyone sorted you with Scott's number yet?

Good call on the Sovtek.

After you install them, a good idea is to leave the amp on overnight.

[ric]

No, i pm'd and emailed him but to no reply thus far.

After you install them, a good idea is to leave the amp on overnight.


Will do. Ta.

[ric]

£8 for 2 Slovtek valves including delivery. Get in!!!

[ric]

My advice would be either a 1960a or a ModeIV, they're the best of the bunch in my opinion.


Whats the diffeence between the 1960a and the 1960b aside from the wattage?


sussed it, the A is angled where the B is not. Does the angle really make any difference in the projection of sound?

[maaszy]

http://www.watfordvalves.com/home.asp

[Fugazi]

Whats the diffeence between the 1960a and the 1960b aside from the wattage?


sussed it, the A is angled where the B is not. Does the angle really make any difference in the projection of sound?

A little bit, yeah. It's a tonal difference rather than a volume difference, and it's mainly for your benefit as the person who will theoretically be stood nearest the speaker. The sound waves projected from the centre of the cones are more compressed than the waves projected from the edges of the cones, so the A cabs sound a little tighter and more even when you're stood near them. Some people also argue that because the speakers aren't all on the same vertical axis they slightly affect each other's tones, but that's really relative.

[ric]

So then, from a gigidy gigging point of veiw it makes no difference as they mic the cab up anyway, but from a practice point of view its better because your generally stood near it and the sound is angled towards you. Have I got that right?

[ric]

*update*

Finally, its all fixed. Turns out, not only had the valve blown but a big long white plastic thing had un-soldered itself. I dont really know what it was or what it did, but when I soldered it back in, bingo. Its now been serviced and cleaned up and it sounds as if it may as well have been brand new.

Ive even got my cab now too. I settled on the smaller (avt model, i think) 4x12. It really emphasis the low end and gives a lovely kick when the guitar is palm muted. In total ive paid less than £150 for a kick as amp set up, well kicks ass for me, Im not the best player by any stretch of the imagination but it sounds how I want it to for my style of playing. so Im made up.

Also, Ive got my guitar rewired, new pick ups and everything(neck,bridge and pots) all reset and polished up for next to nothing and now my guitar sounds like a dream.

Cheers for all your help and advice.