The Amp Garage

Yup, I find that a CLC filter is necessary for all single ended amps when using a speaker with any bass response at all. Using only a capacitor for B+ filtering makes too much ripple (hum). Some deluxe reverb chokes are only rated for 40ma. If I was going to drive this amp HARD I would opt for the l...

That's a real dilemma. Your 100k feedback resister made for good tone but allowed too much hum. Your 1k feedback resister cancelled the hum but caused sterile tone. Neither one sounds acceptable. It seems that you have to put the 100k back in there and find the cause of the hum. I vote for removing ...

My ears hear that you have far too much negative feedback and that makes your amp too sterile. 1k feedback resistor into 5k presence pot. Try setting your adjustable feedback resistor to it's other extreme (100k) and see how it sounds. 101k into that 5k pot would be about perfect.

"White to live and black to neutral ideally" NOT IN THE USA!

Mojo's way of describing the specs is confusing to me. I "think" they mean it is a 330-0-330 at 150 ma. If I were building with 6V6GT power tubes, I would not want any higher voltage or amperage than that. I will be curious to see what others think.

I love these builds cause I had so much fun with my first one-a Newcomb record player conversion. The beginning of an addiction. The heat issue and more gain issues are complicated to answer. The amp running too hot could result from modern line voltage being higher than when the power transformer w...

That 22k negative feedback resistor is to big to allow much negative feedback. You could get a cleaner sound (if you wish) bu using the 2.7k value from the vibrochamp or princeton reverb circuit.

My very unscientific opinion is that 22uf is sufficient. I used the CLC that you have adopted and found it gave me great hum rejection and 22uf gave me sufficient reservoir for a 5881 power tube. I have removed standby switches from my builds after reading assessments by real experts here. You may f...

https://el34world.com/Forum/index.php?topic=15254.0 The Kaligstro post in the above link shows the EC VibroChamp schematic which uses a 2.2k resistor with a 47 ohm tail resistor for the feedback circuit. The 27k value in the original circuit gives the proper amount of feedback when connecting direct...

The negative feedback plan needs more thought. Connecting it to V1b means that all of the reverb circuit is in the loop! V3b is a more logical connecting point but would require splitting the cathodes on V3 and adding a 47ohm tail like the Princeton Reverb has.

If the problem is reverb hum, consider moving the recovery pot to the traditional location after the recovery triode's coupling cap. I predict reducing the already tiny spring output will cause noise at low reverb settings.

Iron Works,
So simple! Why didn't I...?
Craig B

The sound of a cabinet is hugely subjective and related to room acoustics. If you haven't already experimented with this, try moving the cab and your ears around the room. Lower mids and bass are strengthened by reflecting off nearby walls or floor. Upper mids and treble are very directional. They l...

I built a similar amp (but "high power") with good success--eventually. I got a bit of unwanted distortion when using the VibroChamp trem circuit at maximum intensity. So I used the Vactrol-based trem developed by Sluckey and 2deaf. http://el34world.com/Forum/index.php?topic=24334.0 Their circuit pa...