Cornford Roadhouse whistling

[richard]

Posted this on the Cornford site. Wondered what your thoughts are ?

Rehearsed tonight using my Roadhouse 30 combo and took a short break. Started playing a song and when I kicked in the boost I started getting a high pitched whistling noise. I'm guessing pre-amp tube. What do you think ?

Which tube should I replace ?

Cheers, Richie

[Dmoney]

sounds like it.
In my experience it is usually V1 in the preamp.
If you are careful and you have the gain set to a reasonable level with no guitar plugged in, tapping the glass of the preamp valve with a chopstick or something gently is an alright indicator. A badly microphonic valve will make a loud 'ping' noise. High gain amps will generally make a noise if you do this test.

[mikestraw]

I think I will go with you. You should try and replace the pre-amp tube itself.

[richard]

Put in 3 new JJ valves today. Fitted the chassis back in - no sound. Took chassis back out, wiggled the new valves, plugged guitar in - all fine. Screwed the chassis back in - no sound. Chassis out again, another wiggle, sound back but then went again. Tried old pre-amp tubes and I think there might have been an intermittent connection with V2. Made sure it was firmly seated, put amp back together testing after every screw. Seems to be fine now.

Thoughts ?

[Dmoney]

I'd suggest a visual inspection to make sure nothing is being shorted or push about somehow when you fasten the chassis back in the shell.

If any of the valves have poor connections you should be able to gently wiggle the valve while playing to test it. Might be dirt in the socket, poor pin tension, a wire that isn't soldered at all or has a poor joint. Is it a PCB or point to point thing? Not that is matters much. Incidently, how much support have you had from cornford about it? Just wondering.

[richard]

I think maybe there was a bit of gunk in the V2 base but I'm not sure. Couldn't find my contact spray so I just blew in it and pushed the valve in and out a few times. Seems to be okay - I've moved it about a few times and then turned it on and it hasn't stopped working again. It's a PCB amp.

I e-mailed Wally at Cornford USA a couple of times and he replied very promptly but there's only so much you can do from the other side of the pond. I asked how things are with Cornford and he said 'Doing Good'. Although it's a PCB amp it's a very simple one - single channel with a boost, only six controls so hopefully it shouldn't be too hard for a tech to sort out if it comes to that.