Gut and refurb old ss combo

[Greg_L]

Yesssss.

good job man!!! Nothing exploded. You win. Pretty excited to hear how this turned out!!!

Thanks. I'm back home now so I'm gonna bring the Assman into my man-room with me and just leave it on for an hour or so. I'll get some tones tomorrow.

[Lt. Bob]

I made this happen. This isn't a kit. I didn't buy it ready to assemble. I sourced each and every part and figured out a way to make it work.

that's flippin' awesome man ..... lol, you're so talented.
....... and I was the fucking first build I believe ...... that means the gRamp's gonna worth some bucks down the road once you're a famous amp-builder

[Greg_L]

that's flippin' awesome man ..... lol, you're so talented.
....... and I was the fucking first build I believe ...... that means the gRamp's gonna worth some bucks down the road once you're a famous amp-builder

Haha thanks. Sorry but no you weren't the first build. You were the third and fourth. I'd built my own Deluxe Reverb and a standalone reverb unit, which is essentially a Champ, before I did yours. I wouldn't have built you an amp without ever having done it before. I'm by no means an expert at all but I had to get a few under my belt before I felt comfortable enough to build one for someone else. You were my first "for someone else" amp though.


As for the Assman, it's been sitting on my floor idling fully cranked for about an hour now.


Don't call me out....I know it's not cranked in the pic. I took the pic before I dialed everything up.

But it's sitting here full power hooked to a cab. I can hear a faint hiss, which is normal in a wide open unshielded amp with everything dimed. But there's no extraneous unwanted noises. No hums or anything. No oscillation. No squeals pops or buzzes. And this room is electrically pretty noisy. And also I've got just a hodge-podge of random spare preamp tubes in it. I've got a TV on, computer on, lights on, all sorts of shit going and this amp is just sitting here being good. The bias has not budged. Rock solid. I'm super happy with it so far. The PPIMV works fucking great. I've done some mild low volume playing with it and it sounds really cool....really clean when you want it, really raunchy too. Cool amp. Serious tones hopefully this weekend.

[Lt. Bob]

Don't call me out....I know it's not cranked in the pic. I took the pic before I dialed everything up.

I was reaching for the keyboard!

[Greg_L]

Ooooh found a problem.

My power switch just shit the bed and released a spark show. Damn that was crazy. Glad it's still out on the floor. Dumb shit like this is why you can't trust anything in a new build.

I have another switch so no big deal.

[Lt. Bob]

is that one 'o' them LED lights for the jewel light?

[Greg_L]

is that one 'o' them LED lights for the jewel light?

Nah it's a regular bulb.

[Tadpui]

Ooooh found a problem.

My power switch just shit the bed and released a spark show. Damn that was crazy. Glad it's still out on the floor. Dumb shit like this is why you can't trust anything in a new build.

I have another switch so no big deal.

Do you think it was just a faulty switch, or a voltage/current issue in the amp? That's definitely a scary scenario, when your gear starts sparking!

[Greg_L]

Do you think it was just a faulty switch, or a voltage/current issue in the amp? That's definitely a scary scenario, when your gear starts sparking!

I think it's a faulty switch. It never did act quite right. Instead of being a solid *snap* when you switched it, it was kind of clunky. I noticed it before I even put it in but I gave it a try anyway.

[Greg_L]

Okay switch is fixed.

I had to run to Home Depot this morning to get toilet parts. The kids broke the flusher handle on their upstairs toilet. Anyway, I'm cruising through the aisles and it hit me....I need to cover those filter caps. I make a detour to the electrical section just to see if there's anything that could work. Some kind of box...an outlet box! I found one and took it home.

It's got all kinds of holes and notches and dents but fuck if I care. It'll work. And it's only 3 bucks.




The mounting tabs are threaded and they bend inward so I had to be super careful with my measuring and hole drilling. Nailed it though. These are it's mounting screws from the underside.


I gave it a quick and dirty paint job, and that's done. Capacitors are covered and it's very safe and secure. And it doesn't look too shitty.

[Lt. Bob]

I just absolutely love the freakin' junction box cap cover!

That's one of the best things I've ever seen!

[rayc]

NOICE

[Greg_L]

I just absolutely love the freakin' junction box cap cover!

That's one of the best things I've ever seen!

NOICE

It does the trick.

[JD01]

You finishing him off today?

[Greg_L]

You finishing him off today?

Almost. Let's nerd out for one more thing....

I'm pretty confident at this point that this amp is rock solid. My voltages are looking beautiful and it's working great so far so I wanna see what the actual output wattage is. Stock 6G6B Bassmans are about 40-ish watts. Let's get a measurement of what mine is doing.

So we need to inject a sine wave, measure the output in volts AC, convert that to vRMS, and then then do a little formula. My scope has a math function that will do the RMS conversion, but we can also do it with a calculator.

So first I'm gonna inject a 500hz/400mv sine wave into the Bass Channel input. I'm using the bass channel because it has one more gain stage than the normal channel. So here's my little signal generator set to a 500hz sine wave and 400mv output. 1Khz is the "industry standard" for testing equipment, but this is a guitar amp and 500hz usually works better. The 400mv amplitude is sort of an average output between what a single coil and humbucker would put out so we're hitting the tubes with a good approximation of a guitar signal.


So here's the setup...signal generator going into input 1 of the bass channel. The blue trace on the scope is the input signal at the first grid of the first tube. That's exactly what the signal generator is putting out. The input jack is a straight shot to that grid. The yellow trace is around back on the dummy load measuring the total output. The PPIMV is cranked full up. So what we do is turn up the channel volume and we see the yellow trace grow gigantic. We want to measure the maximum voltage we can get with the output (yellow) sine wave staying smooth and clean. That's max clean output. Once it starts to distort we've gone too far. So you turn it up until the sine wave starts to clip, then you back off until it just cleans up again. As you can see that's about 11:00 on the vol knob for this particular test.


So here's the screen. Blue trace is our input and it's measuring 400mv peak to peak just exactly as it should. The yellow trace is that same signal after passing through the amp. It's measuring right up to the 40v mark. We've gone from a puny 400mv to a massive full 40 volts AC. That's amplification. 100 times amplification. Actually it's just a hair shy of 40vac. We'll call it around 38 vac. Still, that's big amplification.


So now with this data we can do some calculations to get a general estimate of what the output wattage is.

Wattage = RMS voltage squared divided by the load resistance. We need to find the RMS value of our output voltage.
RMS voltage is peak voltage x .7071.
Our peak voltage is 38VAC, and we'll multiply that times .7071....and that is 26.869....we'll call that 27 VRMS.
So now with the wattage formula we put in our RMS voltage, which will be 27 x 27 / our dummy load, which is 16 ohms.
27x27 / 16 = 45.5 Watts.

The Tender Assman is a 45.5 Watt amp. And that's a long way to verify what we already pretty much knew.

[JD01]

Scanners gif etc.

[Tadpui]

Scanners gif etc.

LOL I'm right there with ya

[Greg_L]

Lol ok well unless something fails, the amp part is done. It's 45 watts.

Next will be the cab - tolex and grill cloth and speaker.

[Greg_L]

Wellllll......LOL

In light of new developments this amp will NOT be a combo. The amp chassis, now complete with gigantic transformers hanging off of it, seems to have developed a transformer-to-speaker interference problem.

I swear I checked for this. I guess I didn't quite do a good enough job at that. I knew it would be tight, and I clearly misjudged. But sure enough, I put a speaker in the cab, slid the chassis home, and the output transformer just barely touches the speaker cone.

I obviously can't have that, so I guess I'll be converting this into a head.

[Tadpui]

Doh! Maybe it'll be the next big thing in distortion, kind of like people slicing up their speaker cones with razor blades in the early 60s. The sound of a speaker cone rubbing up against an output transformer is bound to be the tone of the next generation!

That is a bummer though. Hopefully inspiration strikes and a good workaround comes to mind. But I bet that it'd still make just as awesome of a head as a combo. Combos are kind of a pain in the butt anyways.