Line out opinions

[Leo_Gnardo]

Ideal line voltage of .775 vac achieved through 470/5k8.
I used 470ohm/10k pot divider off the speaker out with cap across v2 as Leo noted and it works great with no reduction in clarity.

YAY! For the record what size capacitor?

[RWood]

.047 Orange Drop
Tomorrow I'm gonna try .0047, .022, and .1 to satisfy my curiosity.

And this:

[rp]

Please report back on what you hear with the caps, I'm about to try adding the pot, but space is very tight and I'm using a small 16mm pot. It'll be hard for me to try different caps.

[Leo_Gnardo]

Please report back on what you hear with the caps, I'm about to try adding the pot, but space is very tight and I'm using a small 16mm pot. It'll be hard for me to try different caps.

Cap rating need be no more than your peak-to-peak speaker voltage, divided by your resistor ratio. If you have 100V rated film caps, should do with lots of safety margin. Big ol' 600V rated OD, not necessary.

I notice the "book" version has a bass-cutting cap in series with the resistor/pot. Not a bad idea if you find the output of the attenuator too "woofy." Bandlimiting: sometimes a great notion.

[rp]

This post finally got me to play around with the line out, I installed them in the past but just by rote and no pot, someone here or in the links suggested a bread board, great idea, makes a chore almost fun.

I had 470R/2.7K before sounded really nice into an other amp, like pops commented it's a very nice thing to add to a Champ, never tried a PA w/ the 5C1. Goal was to get more usable range out of it, I put a 8R/25W wirewound in the 5C1 with intent of trying it as a boost pedal.

1K pot/10K + 100R to ground as I don't want 'off' rather low-high. This set up hits the receiving amp pretty hard when all up, though I followed the math and it should be less than the 1.23V output for pro use. I need to go somewhere were I can make some noise to really see what's up, see if it works as an OD or if it just sounds like poop, then and maybe tweak the caps. For now seems a .1 input cap might be necessary, it is a bit woofy. The treble cut cap seems to take some of the naturalness away, was trying .022, and maybe the .1 in series is hurting some of the original tone too.

Thanks for the motivation Leo and all.

[martin manning]

Good stuff, rp. Be aware that if you have a NFB loop in the amp, you have some tiny amount of DC on the speaker hot, so the input cap is needed.

[rp]

Good stuff, rp. Be aware that if you have a NFB loop in the amp, you have some DC on the speaker hot, so the input cap is needed.

Important point, I came across no mention of this anywhere on any site. No NFB on this one but I have line outs on most of my other amps. I will have to crack them open and add the cap, now that qualifies as a chore. Not sure if the cap hinders tone, but some DC on an input can't help, and I don't want to be putting any DC into someone's mixer.

Just played more with the Champ as a boost into my 5C8 (cathode biased input) sounds pretty wicked for now, might go nasty ape sh#t flat out, still be fun to find out.

[martin manning]

Note I edited above... It's really tiny, so maybe there isn't any issue there. But you wouldn't wan't any thing getting back upstream either...

[pops]

If you are connecting to the speaker how do you get dc, wouldn't that stay on the tube side of the transformer? I have never used the cap and have put this in several amps with no problem except maybe over driving the input of a P.A.

[martin manning]

With a FB loop the speaker hot is typically connected to the PI tail, which has a positive DC voltage on it, maybe 10-12V. The voltage is divided down by the FB resistor and the load resistance in parallel with the OT secondary DCR, leaving a very small DC voltage. The division is so large that there is only about 500uV left, so it probably isn't an issue.

[pops]

You are right, i should drink more coffee before opening my fingers in the morning.

[rp]

Here it is installed in my 5C1. I got a nifty little 1KA pot from the local electronics place, probably a replacement part for something, had a 2" long thin plastic shaft, I cut it back and it's nicely low profile, as it should be for a little used feature, hard to move accidentally - very intentional looking.

Full up it hits my 5C8 clone, which is what I have handy, like a Mac truck. I did the math looking for around line level of .775V, hope I got it right. If anyone wants to check - Martin?

The final set up is, series resistor 10K, pot 1K with 100R to ground (so it reads 1.1K-100R) + I went with the .1 series cap and the .022 across the pot as the seemed helpful. The 5C1 has ~320V plate with 470R cathode resistor, ~15V bias, 8R OT. I did HBP's math from the Hoffman link and that 10K should be right for .775V.

[RWood]

Please report back on what you hear with the caps, I'm about to try adding the pot, but space is very tight and I'm using a small 16mm pot. It'll be hard for me to try different caps.

I breadboarded caps, 16mm B10k pot, and jack with wires out from chassis to test.

A .022uf 100v film cap worked out the best. It most closely reproduced the speaker sound. I liked the .0047 but it was different sound than the speaker.

The inline cap version was smooth, but middy and thin. The 5c3 nfb hits the grid of power tube after coupling cap so I didn't think it had dc so didn't measure before I closed it up. Is that correct?