• From: Cambridge
  • Registered: 2011-01-15
  • Posts: 912

Topic: Amp tube help!!

Hi

OK my amp is not working properly. I have a DSL401. To get any volume from it at all I have to turn the master and channel volumes up to 10 and this is still barely audible. I have just replaced the tubes in there with more EL84s, and the problem is still occurring. Could it be the pre-amp tubes instead? Any other suggestions?

Thanks!

Jonny L

Videos of my playing: http://www.youtube.com/user/JonnyLowtherMusic
  • Registered: 2008-10-02
  • Posts: 373

Re: Amp tube help!!

I thought that amp used EL34? Could be a bunch of different things wrong with it.

  • From: New Hampshire, USA
  • Registered: 2010-12-21
  • Posts: 3,650

Re: Amp tube help!!

Jlowther wrote:

Hi

OK my amp is not working properly. I have a DSL401. To get any volume from it at all I have to turn the master and channel volumes up to 10 and this is still barely audible. I have just replaced the tubes in there with more EL84s, and the problem is still occurring. Could it be the pre-amp tubes instead? Any other suggestions?

Thanks!

Did you bias them?

"Joe B saved my soul, forever grateful Ron"
"Some people dream of worthy accomplishments while others stay awake and do them"
Skinner #1,JBLP 145(aged),252, (unaged),#285HM, Bburst #026, Joes 052 BCC black LP, Strat> RT,EC Gilmour,Beck,Lenny LP> PK 83,CC#2,3,4,9,Amps>Carol Ann RAH JB-100 SN 001,JB100 Red SN02,OD2, OD3,Tucana 2&3 Triptix,Twinkle land, Plexi ,JB Jub, Jubs,Plexi,Satch,Two Rock>others
  • From: North Carolina
  • Registered: 2008-10-26
  • Posts: 2,926

Re: Amp tube help!!

I had a JCM 800 once that I blew one of the transformers on and it was blowing a fuse on the output side of the amp.  I could still hear the amp when it was pushed wide open but it was as loud as a wisper.  $40 for a new Transformer and labor and I was good to go.  Not saying its the same problem but it could be.

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  • From: Cambridge
  • Registered: 2011-01-15
  • Posts: 912

Re: Amp tube help!!

Hi Big E, nope definitely EL84s!

Hi cindyron, no I don't know how - I will have the amp tech who lives across the street take another look at it

Hi AD3THREE, the amp tech said it was just the power tubes that needed replacing and obviously this wasn't correct so I'll take it back to him

Jonny L

Videos of my playing: http://www.youtube.com/user/JonnyLowtherMusic
  • mbcl
  • BONAMETAL
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  • Registered: 2008-05-01
  • Posts: 1,491

Re: Amp tube help!!

Honestly take it to another amp guy.

Jlowther wrote:

Hi Big E, nope definitely EL84s!

Hi cindyron, no I don't know how - I will have the amp tech who lives across the street take another look at it

Hi AD3THREE, the amp tech said it was just the power tubes that needed replacing and obviously this wasn't correct so I'll take it back to him

Martin
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  • From: New Hampshire, USA
  • Registered: 2010-12-21
  • Posts: 3,650

Re: Amp tube help!!

Jlowther wrote:

Hi Big E, nope definitely EL84s!

Hi cindyron, no I don't know how - I will have the amp tech who lives across the street take another look at it

Hi AD3THREE, the amp tech said it was just the power tubes that needed replacing and obviously this wasn't correct so I'll take it back to him

good luck let us know how you make out
Cheers Ron

"Joe B saved my soul, forever grateful Ron"
"Some people dream of worthy accomplishments while others stay awake and do them"
Skinner #1,JBLP 145(aged),252, (unaged),#285HM, Bburst #026, Joes 052 BCC black LP, Strat> RT,EC Gilmour,Beck,Lenny LP> PK 83,CC#2,3,4,9,Amps>Carol Ann RAH JB-100 SN 001,JB100 Red SN02,OD2, OD3,Tucana 2&3 Triptix,Twinkle land, Plexi ,JB Jub, Jubs,Plexi,Satch,Two Rock>others
  • Registered: 2009-01-01
  • Posts: 665

Re: Amp tube help!!

First guess are the power tubes. But you changed those, right? I thought EL84 amps are generally cathode bias amps, so no need to rebias. But I could be wrong, so don't take that for granted.
My next guess is the phase inverter tube. In most amps it's the preamp tube closest to the power tubes. I'm pretty sure that's the problem. Easy fix, no need for an amp tech to change tubes, especially if it's cathode bias.
So swap the preamp tubes starting with the PI tube.

  • From: Detroit
  • Registered: 2006-06-02
  • Posts: 5,807

Re: Amp tube help!!

preamp tube might have the same pin layout as EL84's. I'm hoping there wasn't EL84s where there should be 12AX7A tubes.

assuming all is right, I always thought DSL's used EL34s

- Nic from Detroit... posting on JB's Forum since 6-2-2006
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  • From: Ireland
  • Registered: 2010-10-25
  • Posts: 57

Re: Amp tube help!!

The 40 watt combo uses EL84's while the 50 and 100 watt heads use EL34's.

Guitars: Epiphone JBLP, Epiphone Les Paul Custom
Amps: Marshall Vintage Modern, 18 watt clone
  • From: Adelaide, South Australia
  • Registered: 2011-10-14
  • Posts: 1,339

Re: Amp tube help!!

Go through your connections with switch lubricant, that's always a good start. I had a bad connection in my effects loop and that caused a massive loss of level, all the bad looking solder joints have now been resoldered and works fine!!

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  • tag2
  • tag2
  • Silver Member
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  • Registered: 2012-02-03
  • Posts: 63

Re: Amp tube help!!

And as always, be very careful inside an amplifier. Even unplugged, it can still maintain lethal electricity until all of the caps bleed off.

  • Registered: 2008-10-02
  • Posts: 373

Re: Amp tube help!!

Try adding a cable between the In and out on your effects loop sometime I would have volume problems with the Jub that would fix them until I got it to a tech. Also find a REALLY good tech I can't tell you how many times I almost sold the Jub because a tech told me something that was completely wrong. Found a good tech and he fixed her right up and she is a monster now.

  • Registered: 2009-01-01
  • Posts: 665

Re: Amp tube help!!

I hadn't thought of cables before. Play the amp without anything in the FX loop and no pedalboard -- just guitar -> cable -> amp. If the problem continues, definitely check the PI tube.

  • DonR
  • Gold Member
  • Offline
  • Registered: 2007-05-14
  • Posts: 98

Re: Amp tube help!!

check speakers as well, that can be the sign of a blown speaker.

DonR