Help! Gig in 90 mins and amp not working!

Jonathangus

JMP 2204 very quiet with no drive on high input, no volume on low input.  Preamp valve?

RiftAmps

http://www.geofex.com/ampdbug/lowpower.htm

robinbowes

Time to get the backup out. You do have a backup, don't you?

jellybelly

If it's passing anything, replace preamp tubes one at a time with a spare good one you hopefully have

jellybelly

Otherwise, cross your fingers another guitarist on the bill has a decent amp and sense of comradarie. I've definitely been on the recieving end of that tactic. The git then complained he couldn't find the drive control on my super reverb

Jonathangus

Very amateur gig for the other guitarist's 60th.  His missus is bringing his practice amp which I'm going to borrow a valve from.

telehack

Pedal board into the desk as a last resort. Been there, done that. Helps if you have a boost at the end of the chain.

viz

Jonathangus said:

Very amateur gig for the other guitarist's 60th.  His missus is bringing his practice amp which I'm going to borrow a valve from.

If you have a valve for the reverb you can use that

Handsome_Chris

Good luck mate.  I hope it get's sorted for you.

Jonathangus

So, it turns out that the valve practice amp is solid state.  So I'm using that.

Swapped V1 and V3 which has got the gain back, but still very quiet.

ICBM

Jonathangus said:

So, it turns out that the valve practice amp is solid state.  So I'm using that.

Can you connect the practice amp to your cab? That will make a huge difference to how good it sounds.

Jonathangus said:

Swapped V1 and V3 which has got the gain back, but still very quiet.

Half of what is now V3 is probably dead.

Too late now, but when you get a new valve to fix it, get *two* valves. Spares are a very good idea if you gig with a valve amp.

While you're at it, get a pair of power valves and at least two each of the fuses as well. (T2A and T500mA, 30mm usually unless the holders have been changed.)

Jonathangus

Well, we got through it.  Not brilliant, but made a noise.  Thanks everybody!

robinbowes said:

Time to get the backup out. You do have a backup, don't you?

Not yet...    We're all very new to this!

ICBM said:

Can you connect the practice amp to your cab? That will make a huge difference to how good it sounds.

No speaker out, unfortunately.  Stuck with the internal 8" speaker.

ICBM said:

Half of what is now V3 is probably dead.

Too late now, but when you get a new valve to fix it, get *two* valves. Spares are a very good idea if you gig with a valve amp.

While you're at it, get a pair of power valves and at least two each of the fuses as well. (T2A and T500mA, 30mm usually unless the holders have been changed.)

Put the valves back in their original positions, and yes, only one half of V1 lighting up.  This is what I've got:

V1 - TAD ECC83 WA

V2 - no idea.  No identifying marks.

V3 - JJ ECC83S

V4 / V5 - Marshall branded EL34

So what would be recommended?  (I know @ICBM is going to say a full complement of RFTs in the preamp.  )

CHrisP86

I’ve got RFT’s in one of my 2204’s and they do sound good to be fair…

ICBM

V2 is another JJ - put that in V1 or V3, not V2 if you can get a Chinese or old-production one for that - but if the only alternative is Russian, leave the JJ there. The EL34s are Shuguang EL34Bs.

Jonathangus

What's the deal with the ECC83S?  That's a higher-gain ECC83, from what I can see.  Any reason it's in the PI, or does anything work in that position?

JMP220478

viz said:

Jonathangus said:

Very amateur gig for the other guitarist's 60th.  His missus is bringing his practice amp which I'm going to borrow a valve from.

If you have a valve for the reverb you can use that

jmp2204 - 50w Master Vol Marshall - no verb no loop - fuck tonnes of tone :-) 

Jonathangus

JMP220478 said:

viz said:

Jonathangus said:

Very amateur gig for the other guitarist's 60th.  His missus is bringing his practice amp which I'm going to borrow a valve from.

If you have a valve for the reverb you can use that

jmp2204 - 50w Master Vol Marshall - no verb no loop - fuck tonnes of tone :-) 

Well, usually...

And there's a Metro loop fitted, and waiting to be wired in.

ICBM

Jonathangus said:

What's the deal with the ECC83S?  That's a higher-gain ECC83, from what I can see.  Any reason it's in the PI, or does anything work in that position?

More or less anything works. You might be better putting that in V1 though.

Jonathangus

Actually, some RFTs on eBay for not silly money.  Look OK?

NOS: https://www.ebay.co.uk/itm/RFT-Germany-ECC83-12AX7-Valve-Tube-New-Old-Stock-V27-1-/384583534876?mkcid=16&mkevt=1&_trksid=p2349624.m46890.l49286&mkrid=710-127635-2958-0

Used (is it actually an RFT?): https://www.ebay.co.uk/itm/RFT-Germany-ECC83-12AX7-Valve-Tube-Used-Tested-V17-/185256460111?mkcid=16&mkevt=1&_trksid=p2349624.m46890.l49286&mkrid=710-127635-2958-0

robinbowes

Jonathangus said:

Well, we got through it.  Not brilliant, but made a noise.  Thanks everybody!

robinbowes said:

Time to get the backup out. You do have a backup, don't you?

Not yet...    We're all very new to this!

I take one of these to gigs:

https://www.sonicake.com/products/twiggy-blues

Cheap, portable, plugs into PA.

R.

ICBM

Jonathangus said:

Actually, some RFTs on eBay for not silly money.  Look OK?

NOS: https://www.ebay.co.uk/itm/RFT-Germany-ECC83-12AX7-Valve-Tube-New-Old-Stock-V27-1-/384583534876?mkcid=16&mkevt=1&_trksid=p2349624.m46890.l49286&mkrid=710-127635-2958-0

Impossible to say really, but not 'definitely dead'.

Jonathangus said:

Used (is it actually an RFT?): https://www.ebay.co.uk/itm/RFT-Germany-ECC83-12AX7-Valve-Tube-Used-Tested-V17-/185256460111?mkcid=16&mkevt=1&_trksid=p2349624.m46890.l49286&mkrid=710-127635-2958-0

Yes - the internal construction is very distinctive, in particular the 'aerofoil' shape plates made from only one piece of metal folded round and with only one seam, rather than the standard construction with a seam each side - and the 'star' mica spacers with much larger points than most other valves.

You can often find bargains with RFTs since they were made very widely available to re-labellers, even by old-production valve standards. Many were sold under old Western European brands, when they were actually manufactured in East Germany - some of them even got branded with British MOD code numbers, when they were supposed to be the enemy during the Cold War...