50 Watt Tone Questions

Dax · Post by **Dax** » Wed Jun 22, 2005 8:13 pm

Has anyone used .1 Output Coupling Caps with the '69 circuit? I am having trouble with extreme highs and mids on my '76 50 Watt 1987. I can't turn the Presence, Middle or treble past 4 without the amp becoming shrill. She sounds great with controls at about 3 with the bass on 5, But I was told runnung the tones below 4 or 5 was kind of putting a strnglehold on the tone and character of my amp. I am using a .022 1st to 2nd stage coupling cap, no bright caps on the lead channel and a 47K NFB to the 8 ohm tap. I put a 100PF cap across the top of the coupling caps (Replacing the 47pf) which seemed to work great with the 6CA7's, but not my JJ E34L's. I realized the 6CA7's just didn't do it for me. They are Cheap EH's. Any advice. What about the 500pf treble cap, what would putting in a 250pf do? What about the slope? Would a 56k give me more range in the mids and highs?

Dax

Billy Batz · Post by **Billy Batz** » Wed Jun 22, 2005 8:43 pm

Messing around in the tone stack is the last place I suggest to do things like what your looking for. Maybe not last but not first. I think .1 in the PI is not only doable, I couldnt play a 69 circuit without it. Much too biting for me. Also you can raise the value of the crossover cap on the PI plates and just put a resistance in series with it so it doesnt totally cut the treble out. That way you have a sort of treble peaking thing right at the end of the signal chain. Better yet make that resistance in series a variable resistor (like with a pot). The only thing that could beef up or kill brightness after that is makes of products (like OTs and tubes and speakers) which works but as a more global solution the PI couplers are about the last place in any amp where you can tweak the tone with components other then a conjunctive filter but thats not for 100W amps. You could attenuate highs earlier in the chain or add bass but to me the farther back in the signal chain you do that on a Marshall the more likely you are to muddy and rumble things up or kill harmonics and cut. You dont want to do either because it should be able to cut and get good harmonic complexity without being too harsh.

Dax · Post by **Dax** » Wed Jun 22, 2005 10:20 pm

So changing the treble cap to a 250pf is not a good idea? Amp sounds great, but i run with presence at 3, Bass at 5, Mid at 3 and treble at 3. Volume full out. I have noticed that the Normal channel sounds pretty good, maybe I'll use it and play around a while.

Flames1950 · Post by **Flames1950** » Thu Jun 23, 2005 12:19 am

Although with humbuckers I can almost tolerate the bright channel on my split-cathode amps (usually presence about 5, bass 6, mids 2 and treble at 4 and you gotta dime the volume) I much prefer the Normal channel on a split cathode right now. Run it like an old Marshall -- dime it all except the bass on 2, 3 max. Fat and rich and squawky.
If you insist on using the Bright channel I think the mid control is the biggest offender -- you crank it up expecting to fatten your sound, but it works the upper mids so much that you get even more brightness. Drop that mid control down and see if you can't get back some of your treble knob's range. It still doesn't give me that god-awful scooped mid sound, the amp EQ just doesn't work that specifically, so don't panic thinking you'll sound like the "...And Justice For All" album.........

Necrovore · Post by **Necrovore** » Thu Jun 23, 2005 12:24 am

That album's guitar tone sucked balls.

Hazy · Post by **Hazy** » Thu Jun 23, 2005 12:30 am

Flames1950 wrote:I much prefer the Normal channel on a split cathode right now. Run it like an old Marshall -- dime it all except the bass on 2, 3 max. Fat and rich and squawky.

We had a thread about the Bright/Normal channels about a week ago...I haven't used the bright channel since on my '78 or my JTM45 clone. Flames, I've been doing just like you said, dime the works except for the bass, it's at about 2. Sometimes I back the treble to 8; otherwise, all 10s.

Much better than the bright channel...I was amazed.

Flames1950 · Post by **Flames1950** » Thu Jun 23, 2005 12:55 am

Hazy wrote:
Flames1950 wrote:I much prefer the Normal channel on a split cathode right now. Run it like an old Marshall -- dime it all except the bass on 2, 3 max. Fat and rich and squawky.
We had a thread about the Bright/Normal channels about a week ago...I haven't used the bright channel since on my '78 or my JTM45 clone. Flames, I've been doing just like you said, dime the works except for the bass, it's at about 2. Sometimes I back the treble to 8; otherwise, all 10s.

Much better than the bright channel...I was amazed.

I'm surprised at how much closer I can get with the Normal channel to those nasally squawky LP/Marshall sound found on 60's albums like Jeff Beck Group stuff. To think I ignored that channel for so long because when you plug in witht the tone controls set for the Bright channel it sounds dull and lifeless.

Dax · Post by **Dax** » Thu Jun 23, 2005 1:00 am

i see that the trble cap on the '68 is a 250. I may try it, and the .1 couplers

Flames1950 · Post by **Flames1950** » Thu Jun 23, 2005 8:26 am

The 250pF treble cap goes along with the 56K resistor though; not sure how it sounds to lower that cap's value with the same 33K slope resistor (someone kick in that link to the Duncan tone stack generator?)
Try just undoing one end of the treble cap and then clip another 500pF in series with the original to make it less of a pain in the ass to go back to stock if you need to (although this was the ex-2204 that now has a Metro board anyway, right? Not a big deal trying the other cap in that case.)

Billy Batz · Post by **Billy Batz** » Thu Jun 23, 2005 9:49 am

It only cuts out upper mids. Not really frequencies that make the amp sound harsh all that much. If you go down to 250 youll notice a bit of a scoop and a bit less gain. Thats kind of a mod on its own. Switching to high values of treble cap is like a gain/mid boost.

Flames1950 · Post by **Flames1950** » Thu Jun 23, 2005 12:24 pm

Where are you hiding lately Dan? You're pretty sparse visiting the last few days. I thought you were gonna catch me when I had no Internet down in Tejas.....

Billy Batz · Post by **Billy Batz** » Thu Jun 23, 2005 2:49 pm

Man Im so swamped with work. I still check the posts in the morning and evening but I honestly am too tired to even think about some of this stuff sometimes

Im gonna try and go back to teaching music at a local music academy. Then I could probably drop much of the contracting work Ive been on.

Flames1950 · Post by **Flames1950** » Thu Jun 23, 2005 3:38 pm

Yeah, I've had to do last minute repairs to my house before the buyers' bank will close, and trying to get packed -- sometimes all the time I have is five minutes here and five minutes there until 11:00 PM when I can barely think straight. Just gotta get through the next couple weeks and the move will be over......

Post by **VelvetGeorge** » Thu Jun 23, 2005 3:39 pm

Just in time for the JTM 45 kits!

George

Flames1950 · Post by **Flames1950** » Fri Jun 24, 2005 12:21 am

VelvetGeorge wrote:Just in time for the JTM 45 kits!

George

Oh baby, no shit!!!!!