Whats on your amp workbench?

Amp tinkerers and people who aren't afraid of 700 volts or so in here....

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Jay
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Re: Whats on your amp workbench?

Post by Jay »

Slowy wrote: Wed Feb 16, 2022 4:53 am
Jay wrote: Tue Feb 15, 2022 8:54 pm
This (your amp):

AF image2.jpg
Actually, it's not. This is my amp.

IMGP0007.JPG
Correct, apologies. The other one is one that got serviced by RectifiedAmps. Same thing though, parts going in all directions with bare leads, etc.

Always have this mental picture of ladies in the Jansen workshop 'soddering' away and sniffing those lead fumes.
Neatness under the hood was not a requirement, speex of putting it together was.
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Re: Whats on your amp workbench?

Post by Anvil Amps Alan »

Jay wrote: Wed Feb 16, 2022 7:41 am
Slowy wrote: Wed Feb 16, 2022 4:53 am
Jay wrote: Tue Feb 15, 2022 8:54 pm
This (your amp):

AF image2.jpg
Actually, it's not. This is my amp.

IMGP0007.JPG
Correct, apologies. The other one is one that got serviced by RectifiedAmps. Same thing though, parts going in all directions with bare leads, etc.

Always have this mental picture of ladies in the Jansen workshop 'soddering' away and sniffing those lead fumes.
Neatness under the hood was not a requirement, speex of putting it together was.
I recognise the new caps and resistors and my labelling of the 4-8-16 ohm taps in black marker. This Amp ended up in UAE.
"Political correctness is a doctrine, fostered by a
delusional, illogical minority, and rabidly promoted by an
unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a turd by the clean end"

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Jay
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Re: Whats on your amp workbench?

Post by Jay »

Anvil Amps Alan wrote: Wed Feb 16, 2022 8:56 am
Jay wrote: Wed Feb 16, 2022 7:41 am
Slowy wrote: Wed Feb 16, 2022 4:53 am

Actually, it's not. This is my amp.

IMGP0007.JPG
Correct, apologies. The other one is one that got serviced by RectifiedAmps. Same thing though, parts going in all directions with bare leads, etc.

Always have this mental picture of ladies in the Jansen workshop 'soddering' away and sniffing those lead fumes.
Neatness under the hood was not a requirement, speex of putting it together was.
I recognise the new caps and resistors and my labelling of the 4-8-16 ohm taps in black marker. This Amp ended up in UAE.
I seem to do everything wrong. Yes, that was yours, ie the AF in the file name. Apologies.

Just hope I will recognise my ones when I look at them in a years time :roll:

The good thing is that with Slowy's, yours and other's help there are now two new Jansen 4/12 kicking around.

Now if only Slowy could get me in touch with this guy who has a 4/12 with reverb....
"I felt as if I'd been had. I'd read to the end what I wished I hadn't begun."

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Re: Whats on your amp workbench?

Post by Slowy »

Jay wrote: Wed Feb 16, 2022 9:39 am
Anvil Amps Alan wrote: Wed Feb 16, 2022 8:56 am
Jay wrote: Wed Feb 16, 2022 7:41 am

Correct, apologies. The other one is one that got serviced by RectifiedAmps. Same thing though, parts going in all directions with bare leads, etc.

Always have this mental picture of ladies in the Jansen workshop 'soddering' away and sniffing those lead fumes.
Neatness under the hood was not a requirement, speex of putting it together was.
I recognise the new caps and resistors and my labelling of the 4-8-16 ohm taps in black marker. This Amp ended up in UAE.
I seem to do everything wrong. Yes, that was yours, ie the AF in the file name. Apologies.

Just hope I will recognise my ones when I look at them in a years time :roll:

The good thing is that with Slowy's, yours and other's help there are now two new Jansen 4/12 kicking around.

Now if only Slowy could get me in touch with this guy who has a 4/12 with reverb....
You mean Ed Pausma?
"We were playing so loud that just one note on the guitar was sufficient".
Ritchie Blackmore.

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Re: Whats on your amp workbench?

Post by Jay »

I have no idea who has such amp but do recall you mentioning it. If the gentleman in question would be receptive to the idea of me cloning his amp, then it would be best to wait till I have my latest 4/12 completed in the blue tolexed cabinet. That way he can see with his own eyes that there are crazy people out there :wink:
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Re: Whats on your amp workbench?

Post by Jay »

Carefully visually checked my latest amp build... then powered it up without valves, measured relevant voltages, all good.

Then valves in and power up - no sparks, no smoke. Measured again and Bias Calculator shows that I am spot on 100% on plate dissipation :D

Plugged guitar in and all go. :D :D

Bit more testing to do and then it will go into its cabinet (ready for the next gearfest).
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Re: Whats on your amp workbench?

Post by MikeC »

Jay wrote: Wed Feb 23, 2022 7:24 pm Carefully visually checked my latest amp build... then powered it up without valves, measured relevant voltages, all good.

Then valves in and power up - no sparks, no smoke. Measured again and Bias Calculator shows that I am spot on 100% on plate dissipation :D

Plugged guitar in and all go. :D :D

Bit more testing to do and then it will go into its cabinet (ready for the next gearfest).
What amp is it?

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Re: Whats on your amp workbench?

Post by Jay »

Another Jansen 4/Twelve with gain and MV mods. Pics too come.
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Re: Whats on your amp workbench?

Post by Jay »

Well, big hum/noise to sort out...
While the first 4/12 I built is quiet as a mouse WITH all pots on 12, this one doesn't like that at all :oops:
"I felt as if I'd been had. I'd read to the end what I wished I hadn't begun."

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Re: Whats on your amp workbench?

Post by Bg »

Had the vibrolux on the workbench today, needed a new grille cloth. This is about the 2nd time I've replaced, if someone wants brown tweed grille cloth and I don't have any handy, I take it from my poor vibrolux! I have a shit load of grill cloth currently but sadly no tweed. Planning on picking a few yards up in the UK.

Had to do some remedial work, lots of loose nuts and bolts. At some stage I'll strip everything out and use some threadlock on all. I'll make a new chassis too at that stage, this was not the best.

Love this amp, it sounds perfect to me. Never to be sold :)

Best part was I finally bought an air stapler to do my car convertible hood, and this was such a pleasure to use on the grille - why didn't I buy one years ago? Manual stapling is tedious, painful and usually requires a hammer blow to seat the bloody things properly afterwards.

edit: the stapler was literally $35, like doh a no brainer...
So, is that low alcohol or no alcohol at all? mmmm, no alcohol, do you want to try it? Noooooooooo.

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Re: Whats on your amp workbench?

Post by Jake »

Picked up an old Peavey Classic 20 with some issues.
Valves aren't seating properly and I think one of the power valves is running too hot - did sound pretty nice when I could get the valves to stay still.
A couple of the larger resistors have visibly deteriorated and when tested with a multimeter they're off by about 20% each, but no other obvious components that I can see.
Plan of attack is discharge caps (just need to make a probe), retension the tube sockets, replace the dodgy resistors and see how it runs after that. Apparently this folded PCB design means that the jumper wires and ribbons are very prone to breaking, so will be aim to move it as little as possible.
Anything else I should look out for?
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Re: Whats on your amp workbench?

Post by sizzlingbadger »

The caps will probably discharge if you switch the amp on, but with it unplugged from the mains. You can check them all easily with the multimeter. I would try new power tubes too, if they were running hot then they could be the cause of the bad resistors.

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Re: Whats on your amp workbench?

Post by MikeC »

Measure the resistance across R21 in circuit (but NOT powered up). You should get a reading of 110 ohms or close.

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Re: Whats on your amp workbench?

Post by GrantB »

Classic 20’s are/were good sounding amps. Better than the 30 tone wise…something got lost on that pathway.
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Re: Whats on your amp workbench?

Post by Jake »

GrantB wrote: Mon Mar 28, 2022 6:52 pm Classic 20’s are/were good sounding amps. Better than the 30 tone wise…something got lost on that pathway.
Got it running a bit happier now, it does sound great! No clean headroom but nice tone even at low volume

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