AC15HW - heater wire trouble shoot

[mel_jr]

Hi,
I'm new to amp building and have been working on modifying an AC15HW - replaced caps, transformer, choke and some resistors. I had the amp sounding quite nice, and decided for the fun of it to replace stock tube socket for V3 with Belton socket.

In the process of the replacement I miswired heater wire to pin 8 instead of pin 9. When I fired up the amp no sound, recognized my mistake, moved heater wire to pin 9. Fired up the amp again and this time sound, but not the nice sound I had thought I had been hearing.I have good ears so I trust something is not right. AT least that is what I think I hear....

*** UPDATE : changed back to the original stock ceramic socket and the amp sounds great again. So this rules out damaged components etc. But I wish I knew why this happened... ***

So I have some questions for you experienced amp builders. In general, how sensitive are components to heat from soldering, or miswiring? During several stages of modding this amp I have resoldered a component and it seems the sound of the amp changes. So what should I expect? are tube amp components ultra sensitive to solder joints, overheated components etc?

Also, is there a way to hook the amp to a scope to see the signal, so that I can see if the picture of the amp changes from mod to mod (so that I can have something other than ears to compare to)?

Thanks in advance,
mel-jr

[andyfromdenver]

Hi. I'm new here so I'll give some background.
Have built about 10 amps and done numerous other projects.
Teach a simple champ or deluxe class locally, and have been studying amps pretty hard for 2.5 years, a mere drop in the bucket for some, but that's where I'm at. I also apprenticed for a super popular tech for a year learning repair and am working on "somewhat" original designs now. (Those with experience will understand sometimes it's really an idea/ stage shuffle and tweaks).
Imo, you are not building, you are "modding" with a very expensive platform.
Why have you changed out so many parts?

That amp sounds totally on the money straight out of the box, and I know from hearing an original 60's vox. (Ok it's sans vibrato but...)

I just don't understand. Anyway, to answer your questions.
Tube circuits can be very forgiving to SOME mistakes.
If you are new to soldering you should heat sink your soldering joints.
You can cook the parts. Especially the carbon comp plate resistors they threw in there.
Yes you can hook it up to a scope and for instance see if you've biased it differently etc. will a scope show if you've swapped say and orange drop for a Mallory 150, no, no it won't.


I highly recommend a cool DIY project like stuff a vibro champ in a crappy $50 fender or something like that and leave that nice amp alone.

That is all and you can hate me if you like.

[rooster]

mel - If you installed a new Belton socket correctly, there would be no audible difference. Always remember this: electricity and an electrical circuit is logical, it's not a living entity trying to out think you. Further, if you experience a hiccup or what might seem like a momentary flaw in a circuit, chances are 99.99 percent assured that the hiccup will happen again. Which is to say, find the problem and fix it.

I think Andy gave you some good advice. I would also add to this that changing a socket in your particular amp - that was performing properly - would be like changing the hubcaps on your car expecting to add some horse power. Don't waste your time.