How can I make my 50 watt sound more like AC/DC?

[Spodeeodee]

Currently my 50 watt is built to the 68 specs as found in the instructions, with the exception of a 100pf bright cap. It has the regular sozo caps and allen bradley CC's. It's playing through a B cab w/ four g12H's. I'll usually play a Les Paul or SG, both with 57 classics in the bridge. Tubes are the JJ's that come with the kit. Oh, and I'll ususally use the bright channel hi input, and occaisonally the low input.

I think it's great as-is, but I'd like to get a little closer to an Angus tone. I dont want a dead-ringer imitation by any means...but closer to that ballpark. Right now my only gripes would be that the bright channel can sound too bright (ALMOST too thin, but not quite), even with the 100pf cap, particularly at higher volumes like 7 or so. Compression also sets in fairly quickly, at 4-5 on the volume.

I've been thinking of changing the spec to be essentially a SS rectified JTM50 too lose some of the 68 spec's agression. From what I've read about JTM50's, that might be more towords what I'm looking for. Or, may just start changing bits one at a time until I find something I like. Maybe start with a shared cathode? To sum it up, the 68 spec seems more VH and Yngwie to my ears, whereas I'm looking for more Angus and Cream type tones.

Just wanted to run it by you fellas before I warm up the soldering iron.


Currently...

[mwm523]

Before you change it, I would suggest you play with your volume and eq settings a bit more. Specifically, turn it down a bit and then adjust your eq. The 50 watter I built did a pretty convincing AC/DC tone with the bright channel volume down around 4 - 5. A lot of people play AC/DC with too much dirt... Their tone is really pretty clean, just a bit of crunch on it, especially back in the '70s.

[Spodeeodee]

Before you change it, I would suggest you play with your volume and eq settings a bit more. Specifically, turn it down a bit and then adjust your eq. The 50 watter I built did a pretty convincing AC/DC tone with the bright channel volume down around 4 - 5. A lot of people play AC/DC with too much dirt... Their tone is really pretty clean, just a bit of crunch on it, especially back in the '70s.

Yeah I hear you. It does a good job with presence 0, bass 3, mid 3-4, treble 5, vol 4-5. But there's still a harshness to it. The thing is it's just a little too harsh...just a tad but enough for me to notice. Maybe I should kick up the NFB? It's got a 47k on the output jack.

[Frankie Sixxxgun]

I know it's not the answer you're looking for, but try changing the pickups in the guitar. I find '57 Classics to be a little too harsh when looking for that Angus-type tone. Try something weaker, like a Duncan Seth Lover. '57 Classics just have that harsh top end on 'em.

[Spodeeodee]

I know it's not the answer you're looking for, but try changing the pickups in the guitar. I find '57 Classics to be a little too harsh when looking for that Angus-type tone. Try something weaker, like a Duncan Seth Lover. '57 Classics just have that harsh top end on 'em.

Thanks for the advice Frankie, but I'm quite fond of the 57 classics. Interesting that you find the top end harsh, as I usually hear people say they're a little on the dull side. Funny how we all hear things differently!

[Frankie Sixxxgun]

I know it's not the answer you're looking for, but try changing the pickups in the guitar. I find '57 Classics to be a little too harsh when looking for that Angus-type tone. Try something weaker, like a Duncan Seth Lover. '57 Classics just have that harsh top end on 'em.

Thanks for the advice Frankie, but I'm quite fond of the 57 classics. Interesting that you find the top end harsh, as I usually hear people say they're a little on the dull side. Funny how we all hear things differently!

Isn't it? I tried some '57 Classics and Duncan 59's and didn't care for 'em. Ended up with some Duncan Seth Lovers and they do it just right for me, at least in my Les Paul.

[OnTheFritz]

Try removing the bright cap altogether (lift a leg), so at lower volumes it's not in the equation.
Also try removing the V2A cathode cap, that adds a lot of aggression.
Just a couple suggestions, and simple enough.
Make sure you have some decent preamp tubes in there as well.

[Spodeeodee]

Try removing the bright cap altogether (lift a leg), so at lower volumes it's not in the equation.
Also try removing the V2A cathode cap, that adds a lot of aggression.
Just a couple suggestions, and simple enough.
Make sure you have some decent preamp tubes in there as well.

Is that the .68uf cap?

[OnTheFritz]

Yes, sorry I wasn't more specific!
I see in your pic you have the resistor *piggybacked* on the cap, so you'd have to have another full length resistor to try this.
If you do, just save this as an *assembly* when you remove it, so you can easily put it back if you wish.
I've got a few *assemblies* kicking around with different resistor and cap values via experimentation. (that was just a side note)

[Roe]

besides getting t-tops, you could remove the .68uf. reduce the screens to 32uf and even experiment with the 250pf/56k tone stack and shared cathode. Also try replacing AB CCs with carbon films

[neikeel]

All the above suggestions are good.

I had some harshness/fizz on my main 50watter. I tried all combinations of tone stack, different input resistors (settled on carbon film). Different valves and bright caps.

Eventually I changed the V1b bypass cap to a Mustard (from WIMA polystyrene) I went to a Mullard CV4004 (M8137) in the PI and a 500pF bright cap. I used a Mullard ECC83 in V1 and V2. I run my preamp voltages higher than the kit as I use a single 8k2 dropper in the B+ line (after the PI)

With PPIMV high and both volumes no higher than 4 or 5 with them patched running into a quad of G12Hs you can get 'that' sound. Interestingly I find an SD antiquity in the bridge better than 57s, Burstbuckers, or 59s for texture and crispness.

[Roe]

You'll need a low output A5 humbucker for angus, preferably a t-top or a pat #. these pups also works well for EC's SG sound

[Spodeeodee]

Thanks for the input. I've always been curious about trying an A5 magnet, but maybe we can keep this thread more specific to the amp.

In other words, if I had t-tops in my SG, what could I do to get the AMP closer to that sound?

[Roe]

angus has used all kinds of 60s and 70s marshalls. which angus tone are you going for?

[Frankie Sixxxgun]

Thanks for the input. I've always been curious about trying an A5 magnet, but maybe we can keep this thread more specific to the amp.

In other words, if I had t-tops in my SG, what could I do to get the AMP closer to that sound?

I thought 57 Classics use an A5 magnet.

Anyway, I just finished modding the B+ voltage to my preamp in my 50 watter, and it definitely gets more open and Angus-like after doing so. It took a lot of the aggressive sound out of the amp, and, for lack of better works, made it more open and old school sounding.

Next to the bias pot there's a 10k resistor chained to an 8.2k resistor in a straight line. Just alligator clip past the 10k resistor to try it. If you like it, like I did, just pull the resistor and jump it with a piece of bus wire.