The Amp Garage

So, I'm going over the layout verifying the NFB circuit and lo and behold, the 390 ohm resistor after the NFB resistor was bypassed with a 22uf electrolytic for some reason. Removed the cap and all is good in OTS land. Can you explain why someone would do this? The resistor is near the cathode (kin...

Looks good, I like your amps. You have a unique building style.

What's happening with the front panel?

Love those tube cut outs!

Are those inserts in them?



EDIT: Just saw another thread where you said that was a mistake. lol! I like em

I like the heater wiring, neat and no close to the other tube elements/wires! Just how Merlin describes it in his preamp book.

What's BC style? Is that the guy who only does right angles?

Looks like you didn't flip that bolt

Thanks Martin. I'm calculating 6.8dB drop with the split load output, should be quite noticeable. A unrelated question while I have you here... Merlin says center biasing is -2V in his book, where the grid curves only go to -4. The datasheets I look at show curves that go to -5V. In reality is cente...

Scenario: Split plate load common cathode gain stage. The resistor going to B+ is 56K the resistor going to plate is 47K. Lets say the gain (A) of the stage is 100. The output comes from either the plate or the node connecting both resistors. The output feeds a 0.01uF cap with a 1M resistor to groun...

Missing ground?

CFs are generally used before fx loops to achieve a low impedance drive, thereby mitigating signal degradation. However, a tone stack generally has a high impedance output, so you may wish to review such an arrangement as part of the design rationale. Good point I was planning on using a simple sin...

Ah perfect, that is exactly what I was going to try.

What was before the 5879? How did this design work out for you?

One question about the morth control, why did you connect it back to the cathode and not the grid? Don't understand your comment about buffering the triode mode...

Gross!
Did it get fried by the filament circuit?

roberto wrote:Take a look at the attached file: split load and frequency shaping.

Very interesting stuff

How are you calculating the corner frequency for 2nd and 3rd cases?

Working on a design that has a 5879 pentode in it. This tube has a plate resistance of ~2M. This translates to a very high output impedance compared to a standard 12AX7. As a result having a tone section after the pentode does not make a whole lot of sense. After the 5879 pentode there is a effects ...

I use a Delta Pro 12A with a #124 amp. Works ok, it's a little on the dull side compared to a EVM like everyone says. I have a Tonker and Swamp thing in an oversized 212 (ala RFs). It's again a ok combo, a little on the harsh size. If I did it again I'd say save your money and get the real deal (EVM...

It is very clean though and does include all the goodies.