The Amp Garage

Thanks for the suggestions. I'll give the 100pF cap on the amp volume control a go and report back when it's done. I'm basically looking for two things with my amp (an Amp Maker WF-55 kit): 1) Less volume. I've addressed this by changing the 12AX7 for a 12AY7 and it worked well, but I still rarely h...

This is all brilliant information, thank you so much. I'm coming from an audio engineering perspective (been a full time mastering engineer since 2011), so defining the correct terms is important to me. Electrical engineering, well I'm just a beginner, so thank you guys for helping me grok this stuf...

Quick question: Does a so called "Bright Cap" on a volume control (whether it be in the guitar, or the preamp input volume control on a simple amp like a 5F1) actually boost highs, or does it really act as a HPF and rip out lows, leaving the highs alone? I am guessing the latter, but I keep seeing i...

Thanks so much Martin! I knew I could rely on this place for some clear and experienced answers. So, it seems that most of my fears are ungrounded. I think the key penny that hadn't dropped for me was this: The signal voltage becomes relatively larger with respect to all of the other voltages, reduc...

Hi all, Something that I've been wondering about recently that I don't fully understand, but know I'll get a good answer here! The kit maker for my 5F1 clone sent me info on how to add a Wattage Reduction Switch to my amp, that goes from 4w (standard) to 2w or 0.4w. This apparently cuts the loudness...

Thank you for the in-depth answer Martin. It's a darkish sounding amp anyway, so I'd hate to lose any more high end. I'll try and hunt down the pull switched pot.

3) The online TSC shows that with the pot at minimum you have maximum attenuation of frequencies, and with the pot at maximum you essentially have it bypassed/zero attenuation. I'd like it to be the opposite way round. i.e. pot at minimum = no effect, pot at maximum = most effect. Is this possible, ...

2) Where exactly in the amp schematic would it be wisest to fit this pot? (See schematic in original post). Between the C1 coupling cap and the Volume control VR1, or directly after VR1? Or later in the circuit directly after the C2 coupling cap before the power stage?

1) The online TSC shows that with the pot at 10, nothing happens, it's like NOT having the EQ in the circuit. Will this actually be the case? What would the insertion loss of those components likely be, either in level, or frequency response? I ask because RR also shows a version with a switched pot...

I want to add this fairly simple looking Framus Mid (and slight Bass) Scoop EQ control to my 5F1 clone. It should allow a bit more of a Blackface sound, and because I do a lot of Funk strumming recently, it'd be great to be able to rip out some low end and mids. Here is my amp schematic: Schematic.p...

Thanks once again Martin, I'll order the 33k!

2 x 15k resistors in parallel will give me that, right? Literally just solder them next to each other using the same solder connections? Can't find 7.5k resistors on the Tube Town site.

martin manning wrote: ↑Wed Oct 18, 2023 12:24 pmI would say 7k5, which is about 5x the cathode resistor value on the triode the NFB is going to. If you go lower, you will be moving its bias point significantly.

Thank you. I might just give that a go!

It's working! Thanks to you both for hand holding me through this (I'm a total newbie). I don't know what was going on at first (stray solder whisker or something?), but after wiggling the solder connections all is working as expected. I get the nice clean tone with the pot at lowest, and a bit more...

OK I wiggled all the solder connections I had made/unsoldered/resoldered and took readings again. Now with lug 1 and Ground I'm getting from around 3 ohm to 9.3kOhm when turning the pot. Can I ask what should it be reading?