The Amp Garage

By putting an attenuator on a setting that expects a load, and not hooking up a load, you're presenting a higher impedance to the amp, which puts a bit of strain on the output transformer and output tubes. As you've observed, doing this isn't an instant death sentence, but it's not good for the amp....

Cool amp, looks as heavy as my old PS300.

The UL connection keeps the screen voltage lower than the plate voltage, which is much kinder to the screens than the typical fixed screen supply.

I have something similar that'd I've used in my shop forever. The main differences between the two are that I don't have the noval socket or adjustable cathode resistor, and I'm using a tapped Hammond OT, so I have three output jacks "Lo Z, Med Z, Hi Z" :) I also have bypass switches for the second ...

Very late to the thread, but I really think the shield was originally to keep the output tube heat away from the can caps, which were in close proximity and were not hi-temperature spec electrolytics. It also helped guide the hot air around the output tubes up and through the top vent in the cabine...

The brand of transformers is the only link between the two. Partridge, like all transformer manufacturers, routinely made custom transformers to spec for amp manufacturers.

Cool amp, btw.

Sorry, I missed this thread Q - any good quality transformers with appropriate specs should work fine. The circuit and the stiff power supply are the elements most responsible for the Hiwatt sound, imo.

I've read that JJ 6V6 tubes are closer to 6L6 in internal construction. This would explain why they bias a bit different than NOS 6V6. This is also likely why they seem to handle higher plate voltages than true 6V6 tubes.

I like the TADs for current manufacturer.

LOUDthud wrote: ↑Tue Mar 07, 2023 8:12 am An experienced PCB designer would design with oversized holes/pads to make repair easier.

As if "repairability" is on any modern mass manufacturer's radar.

https://www.mouser.com/c/?q=xicon%201w%20resistor

You can buy one for $0.20 (and pay $12 for shipping, sigh).

Note the KOA/Speer ones are ~47mm (< 2") long, per the datasheet. The Xicon (Tyco) 1W carbon films are inexpensive and work well, are only a bit larger than the old 1/2 watts, and are longer that the new 1/2 watts (~60mm). They are also available in a wide range of values. This latter is becoming mo...

In the UK, the live wire is brown, the neutral wire is blue, and the ground wire is green/yellow.

The live wire on a US socket is the longer blade, or top left when looking at the socket with the ground hole on the bottom. The other blade is neutral.

Andy has a good point. A lot more stressed output tubes fail via screen grid vs. any other mode. It just cost money to reduce the screen voltage significantly (particularly before the advent of HV FETs) - this is the main reason why traditional designs don't do this.

I'm not quite sure what you're asking. :) To my ears, 6V6s sound like mini-6L6s. I quite like them, and use them in all my more recent 20-ish watt builds (and once even in a 4x 30-ish watt design). They are typically run at voltages in excess of what the old data sheets recommend. They are similar i...

A constant current source (CCS) does it's best to keep the current flowing through itself constant (as the name implies :)). This means it appears as a very high impedance looking "in" and therefore it will allow the voltage across itself to change almost like an open circuit. An ideal LTP design wo...

dragonbat13 wrote: ↑Mon Jan 30, 2023 11:51 pm Not wanting to use carbon comp at all. Carbon film if not metal film.

Sorry, my bad.