JTM45 Not Loud

[LJay942]

Plugged a guitar in today and the amp seems pretty quiet. I mean has output but it isn't what I expected. I have checked and re-checked the components and am almost positive they are correct. Anyone see any mistakes in my pictures? The amp seems a bit sterile and dull. Doesn't have the oomph I thought it would. Nor does it make my ears ring. I thought for sure this little monster was going to be loud.

Or am I just expecting the wrong sound out of this amp. It doesn't seem to crank well either does get real dirty or loud sort of clean and un-responsive. Bias is set per instructions. I'm running through a 8 ohm 2x12 cab w/Greenbacks (amp is set to 8 ohm). It does not sound anything like the YouTube clips that I have been listening to. Any advice on what to check? Bunk tubes, bad soldering, or wrong component installed?

I figured it was easier to make another thread than keep updating a previous one. Hope thats alright:)

Here is the link to the album.
http://s639.photobucket.com/albums/uu12 ... o%20JTM45/" onclick="window.open(this.href);return false;
guest password is: metroamp

[Big Jim]

Ljay, I am not the guy to ask when it comes to troubleshooting. But I have however recently built this amp. The one thing that tells me something is not right is you saying that the amp doesnt make your ears ring. These JTM45's are loud as shit. My amp stays pretty clean up until abou 3 or 4 (which is pretty loud). From there it just gets gainier and gainier. A good ACDC type tone is found around 5 or 6. Have no fear, these guys on this forum are nothing short of amazing when it comes to troubleshooting these amps (or any amp for that matter). I had a couple of issues on my build, and they had me straightened out before my soldering iron even got cold! Jim

[LJay942]

These guys are the best aren't they? When I was on the fence about ordering one they quickly got me to think otherwise! I'm just trying to provide them the best possible pictures and description I can help me get this sucker rocking!

Update: I noticed that my Presence pot was grounded incorrectly (not at all) I have since run a lead from the third pole to the ground rail wire.

Here is a picture. Sorry for the quality it's dark outside and I just snapped a quick one to give you guys the jist.

http://i639.photobucket.com/albums/uu12 ... CN2785.jpg" onclick="window.open(this.href);return false;

Thanks again,

-Larry

[MBD115]

Sorry to hear you are having problems. Hope you get them resolved asap so you can start enjoying your new amp.

I looked at all the pics and nothing jumped out at me, but I'm only a noob so I might of missed something. I could not see if you have your speaker impedance switch wired correctly by those pics. I would double check that.

Have you double checked the voltage charts. I would recommend you go back through the voltage chart in the instruction manual and double check all the voltages.

Your amp should be plenty loud with a very full and beautiful tone and should be really quiet to hiss and noise up until a high volume where you might start to hear a little hiss. After about 7 on the volume knob you should get some dirt/grit in there also.

I find my amp to be very responsive to my guitar volume, pick pressure, and pickup height. If you have a faulty chord, weak or low adjusted pickups, or are using much reduced guitar volume then this might explain a reduced output from the amp. I believe mine would act the same way. The 'thin' tone I can't explain. I haven't though about the word 'thin' at all when playing my amp, so I don't think it should sound thin. I don't know.

Might be a cold solder joint somewhere. Again, I don't know.

Good luck!!!!!

[LJay942]

Sorry to hear you are having problems. Hope you get them resolved asap so you can start enjoying your new amp.

I looked at all the pics and nothing jumped out at me, but I'm only a noob so I might of missed something. I could not see if you have your speaker impedance switch wired correctly by those pics. I would double check that.

Have you double checked the voltage charts. I would recommend you go back through the voltage chart in the instruction manual and double check all the voltages.

Your amp should be plenty loud with a very full and beautiful tone and should be really quiet to hiss and noise up until a high volume where you might start to hear a little hiss. After about 7 on the volume knob you should get some dirt/grit in there also.

I find my amp to be very responsive to my guitar volume, pick pressure, and pickup height. If you have a faulty chord, weak or low adjusted pickups, or are using much reduced guitar volume then this might explain a reduced output from the amp. I believe mine would act the same way. The 'thin' tone I can't explain. I haven't though about the word 'thin' at all when playing my amp, so I don't think it should sound thin at all. I don't know.

Good luck!!!!!

I'm going to try and snap a picture of the impedance control as I didn't get a good one when I was outside. My voltages were all +/- 10% which I feel is acceptable correct?

[LJay942]

Photobucket album now has pictures of impedance switch wiring.

[MBD115]

+ - 10% should be good. I think the wall voltage can effect those reading. Once I posted the heater voltage on an amp I was working on and someone replied and told me what my wall voltage was. And he was right.

I guess I would then start at Step1 again and trace all the wiring and closely inspect all the solder joints. I would also check through with my ohms meter to make certain. A lengthy process I'm sure.

I've had bad preamp tubes in the past that reduced my output volume. I had a bad PI tube that popped and quit making sound all together. I have read that output tubes can reduce in volume and bet brittle/thin sounding. I'm not sure about the rectifier tube and what it might do if bad/weak/etc.

Again, I wish you well and hope you get it figured out. I know I can't be of much help to ya.

[LJay942]

I tried moving the preamp tubes around still with no luck.

Those tubes sure do look pretty glowing in the dark though.

[MBD115]

If you voltages all checked out right then that should be normal.

The impedance switch looks good to me.

Your 2x12 cab is wired ?ohms, and you have the switch set properly to match it. Correct?

I agree with the above poster also.. My 45 is 'as loud as shit' too.

[LJay942]

If you voltages all checked out right then that should be normal.

The impedance switch looks good to me.

Your 2x12 cab is wired ?ohms, and you have the switch set properly to match it. Correct?

I agree with the above poster also.. My 45 is 'as loud as shit' too.

I have a Geezer Sound Company 2x12 w/ Celestion Greenbacks. It has two mono jacks the cab is wired for 8 ohms (no switch) I have had this cab for quite some time and am almost 110% positive the cabinet is not the culprit.

Thanks,

[MBD115]

I was only hoping you were using the right impedance switch setting for your cab, as it appears you are using the 8ohm setting which seems correct.

Again, I don't know.

Good luck

[LJay942]

I was only hoping you were using the right impedance switch setting for your cab, as it appears you are using the 8ohm setting which seems correct.

I just gave your other post a quick read through. After reading that... To me... if the amp is sounding thin and running at a reduced output volume then the problem might be the OT. I hope this is not the case!!!!! But I do fear that now.

Again, I don't know.

Good luck

Could the transformer come DOA? I don't think I have done anything to make it blow..

I always had the cabinet hooked up to the head with a speaker cable.

Really hoping that the Output Transformer is not the culprit.

[myfoot]

Has it played loud before or did it just start doing it? What kind of tubes? Have you re-checked the bias? Cold bias could cause this ( someone else just went thru this ) Resistor values look correct ; the ones a lot of folks including myself screw up look to be right.

[LJay942]

Has it played loud before or did it just start doing it? What kind of tubes? Have you re-checked the bias? Cold bias could cause this ( someone else just went thru this ) Resistor values look correct ; the ones a lot of folks including myself screw up look to be right.

I have triple checked all the components. bias is set at 42.6 (V4) and 42.8 (V5) as per the manual. Resistor values were triple checked and confirmed with multimeter. I also rang out all the leads running to and from the turret board.

I'm trying the best I can on my end of things. Name things to check and I'll rattle off values

Tubes are as follows

3x JJ 12AX7
2x JJ KT66
1x JJ GZ34

[myfoot]

Have any other preamp tubes to check with each socket? Could be a bad tube. They can be bad right out of the box.