The Amp Garage

I suggest you do some yoga. Even scarce, good vibes are contagious. If this is directed at me, I do yoga, (and meditation). But i see my blathering may have been misconstrued. I was just considering the impact on my situation and realized it will affect more than amp construction. For many of us I'...

elections have consequences As does everything. There are wars over trade. There's an old saying that warns of breaking another man's ricebowl. The current attempt to realign the trade balance between the two largest economies will shake the net and have far reaching, and many unforseen consequence...

Mikante wrote: ↑Sat Jun 07, 2025 1:08 am Yes, exactly, how can i calculate the size of the shelf port?
The diameter of the vent is 4 inches in the drawing.

It might be time to purchase speaker cab design software.

The 800 series cabs have a shelf port. The two supports make it look like 3 separate chambers.

Multiple small caps definitely is the way to go.
I don't use 22uF as cathode resistors. I use 2uF to 5uF.
How much low end do you need?

Just another reason to avoid electrolytics where space permits. Unless you manufacture on a large scale on thin margins.. I agree. It just might be possible to replace them all. I typed in a lot of stuff, and realized that its better as a separate post. See the thread on the Immortal Amplifier. I n...

RG. So what’s the deal with non polarized electrolytics ? Polar electros oxidize one of two foils, the other being left bare. The bare aluminum foil serves only to make good contact to all of the electrolyte, which is the actual conductor on one side of the oxide. The oxidized foil is the other con...

Roe wrote: ↑Tue May 27, 2025 6:04 am

TUBEDUDE wrote: ↑Mon May 26, 2025 10:53 am It seems to me the bias circuit should be grounded with the power amp ground, not the preamp.

yes, with the screens: https://valvewizard.co.uk/Grounding.pdfv

Yes, as i stated above.

didit wrote: ↑Mon May 26, 2025 7:49 pm Hello --

Try mu-metal.

..

It works well, but is expensive, and if cut or bent it requires annealing to keep it's effectiveness. I would think steel would work better than aluminum. At any rate he solved it, and cheaply.

The cathodes of the power tubes, or the ground side of the cathode resistors in the case of cathode bias. This should also include the center tap.and the negative sides of the power tube plate and screen grid filter caps. On some builds, if you also include the P.I. filter, you reduce noise better t...

Very nice clean build, as usual with your builds! Yeah, not every great sounding build is also bedroom friendly. How's the baseline hum? I've never worked on a Liverpool, does the original have the O.T. and power xfmr on top of each other? It looks like Ken had real estate to spare. Just curious. I...

It seems to me the bias circuit should be grounded with the power amp ground, not the preamp. And where is the power amp ground? It should be on a bolt to the chassis near the power transformer, with the power tube plate and screen supply caps negative terminals. But you want it to be connected to ...

It seems to me the bias circuit should be grounded with the power amp ground, not the preamp.

Very nice clean build, as usual with your builds! Yeah, not every great sounding build is also bedroom friendly.
How's the baseline hum? I've never worked on a Liverpool, does the original have the O.T. and power xfmr on top of each other? It looks like Ken had real estate to spare. Just curious.

Cost is king. In the battle of degraded lifespan vs. expense the bean counters usually win.