#124 Questions

[Smitty]

The carling-style with both lugs on top works well in that location.

[Bombacaototal]

The carling-style with both lugs on top works well in that location.

Thanks Smitty, mine is actually a carling as well. Do you have the part number of the item you mentioned by any chance?

[Smitty]

https://www.tubesandmore.com/products/s ... older-lugs

[norburybrook]

The carling-style with both lugs on top works well in that location.

Thanks Smitty, mine is actually a carling as well. Do you have the part number of the item you mentioned by any chance?

Or in the UK, Mike is a member here too


https://modulusamplification.com/Carlin ... 75378.aspx


M

[Bombacaototal]

Great! Many thanks Smitty and Marcus

[Bombacaototal]

...

[Bombacaototal]

Thanks for the suggestions regarding the mains switch. Indeed much better like this.

Now which lug is the middle lug (2) and which is the outermost lug (3)?

[pompeiisneaks]

Not sure I understand your question.

the mains switch I see has two lugs. Order of connection doesn't matter as it's only an 'on/off' type SPST switch. Therefore you can only have on or off, and your power comes into the switch and out the other side, no matter which side you choose.

Or are you referring to the impedance selector switch I see there? I think the lug order from what I see is 1 (switched/active now) is left, 2 is second from left, 3 is third from left and the last lug on the right is common.

Is that what you're asking?

~Phil

[Bombacaototal]

Not sure I understand your question.

the mains switch I see has two lugs. Order of connection doesn't matter as it's only an 'on/off' type SPST switch. Therefore you can only have on or off, and your power comes into the switch and out the other side, no matter which side you choose.

Or are you referring to the impedance selector switch I see there? I think the lug order from what I see is 1 (switched/active now) is left, 2 is second from left, 3 is third from left and the last lug on the right is common.

Is that what you're asking?

~Phil

Thanks Phil, that clarifies. I always thought there was an IN and an OUT on those switches. But good to know it doesn’t matter. Many thanks

[Bombacaototal]

I usually like Wirewound resistors for my dropping resistors but I use Metal Oxide on the rectifier board.

On one of my amps I was struggling with the bias range and decided to drop the rectifier resistor for a better range, and given I had a spare WW of the value I wanted I fitted it there. Any reasons for swapping them to MO?

[Bombacaototal]

Quick question for those who built amps with reverb. I just finished a SSS 004 like amp. Originally I had a ground loop on the reverb and by replacing the pan grounding from output (red) to input (black) the ground loop was gone. With the pan outside of the head the amp os super quiet. The pan is mounted to a thick wooden platform and inside a sleeve. The donor head cabinet is the Two Rock Custom Reverb Signature from 2017. Whenever I add the reverb pan inside the head I am picking up a fair amount of noise. I tried both 180 degrees positions and the quietest is with the return (red) furthest from the transformers. But still there is a considerable amount of noise compared to the pan outside of the chassis.

I also tried a few different reverb pans

I am using 100W classic tone transformers with the vintage mounting OT. Below a pic of the pan placement and distance to transformers. I tried adding a copper foil in between the trannies and the pan but no avail. Any tips?

[rootz]

I had my latest amp in a head shell for some time, but can’t remember that I had a hum from nearby PS components like you do.

Some questions. Is that reverb pan grounded in some way? Does the hum get less when you place a jumper between the amp chassis and the pan? Does the hum get less when you put a metal cover over the underside of the pan (make it a closed box; ground the plate)? Is the hum 60 cycle? Any difference when you replace the shielded cable to the reverb by something different?

[pompeiisneaks]

It can be very tricky eliminating hum with a reverb pan in a head unit. I had to put a bit of cardboard on the top of the pan, and rotate it at slightly off of perfectly level in the bottom of the head so that it wouldn't hum. This was in a reeves space cowboy, with amazing sounding reverb, but that hum... ugh. Even then, it still hummed but was way lower level and not really noticeable when played.

~Phil

[Mark]

Wouldn't mu-metal do the trick?

I suspect it would be quite expensive though. Would aluminium work as as shielding?

[Bombacaototal]

I had my latest amp in a head shell for some time, but can’t remember that I had a hum from nearby PS components like you do.

Some questions. Is that reverb pan grounded in some way? Does the hum get less when you place a jumper between the amp chassis and the pan? Does the hum get less when you put a metal cover over the underside of the pan (make it a closed box; ground the plate)? Is the hum 60 cycle? Any difference when you replace the shielded cable to the reverb by something different?

The reverb pan itself is grounded on the input (black). As mentioned on the previous post it was originally on the return side but I had to move it due to the ground loop.

It made no difference by adding an alligator clip in the pan and chassis. I tried a different rca cable too

Attached a recording of the hum and a pic of how I have the pan sitting on a wood bar and the sleeve and the copper foil I used between the pan and the transformers