trinityamps.com

After thinking about this off and on yesterday I realized that I was not a total NOOB. Well I am a NOOB but my mind was not out the window.

I know that both ways have been done and they both work but if your goal of cascading is to have a really 'high gain' preamp and still have a flexible tone stack and master volume then here are my thoughts on it.

If you cascade the TMB into the normal channel, with only a double pole double throw switch, you basically have only two options for taking the signal from the TMB. You could take the signal after VR1, the TMB gain, but then you are throwing away the second stage and tone stack so that is no good. Or you could take the signal after VR7, the master volume. Now if you do that and you do not have an attenuator, then you are basically going to be using the normal channel gain as your master volume which means you are not fully utilizing that gain stage (unless you like things really loud). Even if you had an attenuator and could crank the normal gain, the problem is that your tone stack becomes a fancy 3 knob tone control for your 'overdrive' and your final tone shaping is done with the normal channel tone control which is just not as good as a full tone stack.

Now if you cascade the normal into the TMB, then you will have the normal tone as your 'overdrive' tone, you can crank both channel gains and you still have the tone stack for final tone shaping. Then you can set the master volume to a comfortable listening level and enjoy full cascaded high gain bliss.

If it is just a matter of convenience of what channel you plug your guitar into most. Just go get a patch cable, plug into the normal channel and jumper the inputs. When you are not using the cascade or the normal channel then just turn the normal gain down. If you really do not want to jumper the channels then I can draw you a schematic using a triple pole double throw switch that will inject the normal channel in between V1a and V2 but the switch would need to go on the back of the amp and makes wiring a bit more tricky.

With that said, each of you now owe me a sound clip.

And as ROCKSTAH once said 'Go do some pushups'.

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Les

http://www.soundclick.com/unimind

I knew that and couldn't understand why you seemed to be running yourself down so much.


We have done it this way before, and it's actually quite OK. The TMB channel's volume control, then becomes an additional Gain control, and then the Normal channel's volume control becomes the overall master volume before the PI. I don't see how that means you're not fully utilising anything....


To some extent that is true, and that's what I was getting at before. It means that the tonal range of the TMB stack becomes somewhat limited by the frequency response of the Normal preamp stage. So that has to be set fairly carefully, not to have too much bass, but to still allow some usable control range. When you're using a lot of gain, you have to restrict the bass so the tine doesn't get mushy, and to me it appears you've already taken care of that in your mods. The TMB tone controls do still work just the same, and the Normal channel tone control then allows you to trim the top end to suit.


Yes, we're on the same lines here.


You're confusing me here. Patching channels together doesn't make anything cascaded....

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Great tones come in small glass jars!

With the channels jumpered you guitar signal is live at both noraml and TMB inputs so you wont have to keep unplugging your guitar from the TMB input and into the normal input when you want to run cascaded. Just that matter of convenience thing.

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Les

http://www.soundclick.com/unimind

I am going to try as soon as my kit arrives. Now i ordered a V6 kit, how much do you all think that is going to complicate matters?

I was thinking I would run the 6v6's mostly in the normal channel, for some clean sounds. Then use the El84's for the TMB with the all the brown mods

I don't think there should be any problems. The only difference in the power section will be the 220Ks for the grid references and the 50uf for the bypass caps. I think they should work with both tube sets but better to have Phil weigh in on that.

Are you going to build it stock first and then apply the brown mods so we can hear a before and after?

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Les

http://www.soundclick.com/unimind

I could do that perhaps. I also happen to have a stock plexi model sitting right here. I built it for a friend , and I'm still waiting on the head cab. I can tell you that while it sounds very very good in its own right, it sounds drastically different from yours. My guitar is also different, and my playing style is also. I have never had an amp like these. I have played Fenders my whole life, used tube screamer type pedals for overdrive. I have a few Fender amps, and one Dumble clone, lately I have just had an itch for a Marshall style amp, and to learn some of the styles that go along with these tones. My days of Jazz snobbery are beginning to wane, I am feeling a strong urge to Rock !!

Our brother has come out of darkness and seen the light!!!

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Great tones come in small glass jars!

I am starting to think that the key to my brown sound is in my speaker cabinet. When I first played this amp after I built it the sound was there. http://www.unimind.us/TrinityPlexi1.mp3
In that clip the amp was the stock Plexi circuit except for 33K on the tone stack slope and 220K/5.6K on the el84 grids. Yesterday I put the stock 470K/8.2K on the grids and there was barely any difference in the sound. The 8.2K grid stoppers actually smoothed out the extreme high end frequencies so I have left those in. The 470K grid references maybe reduced the gain very slightly but otherwise had no effect so I returned those to 220K. The rest of the mods in this thread are all related to the preamp voicing and I think they are key to getting a good brown high gain tone but the part that makes my amp have that "seriously brown sound" or "sick brown sound", as some have described it, I think is the combination of the amp voicing PLUS the Peavey speakers I have.
I guess we will need to wait until someone tries this circuit with other speakers and see what the result is.

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Les

http://www.soundclick.com/unimind

I agree. I don't think the speaker on its own would make your amp sound brown. However I guess it may help smooth off some high end to make the overall effect browner. I wonder if your PV speakers are anything like the Celestion Lead 80 - http://professional.celestion.com/guita ... l.asp?ID=8 Do you have any PV specs to compare against? I think your mods do help to make the amp browner in gain and voicing, and even more so, when you go cascaded.


Are you really sure about that?? Everyone else who has tried out 220k vs 470k grid reference resistors in the power amp has found less gain and later breakup with the 220ks. That's one of the reasons Vox amps have a later breakup than the Marshall 18W. The theory books will also tell you the same. In any case for fixed-biased operation the grid reference resistors can't be higher than 330k IIRC.

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Great tones come in small glass jars!

No. I am not sure. I think I was just trying to hear something but I was mainly listening to the sick nasally compressed brown sound and it really had no effect on that.

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Les

http://www.soundclick.com/unimind

I would also expect more of the compressed brown vibe with cathode-bias, rather than fixed-bias.

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Great tones come in small glass jars!

I found this: http://www.loudspeakersplus.com/product ... N-SP-1225/ I have the 4 ohm version from 1978 but that is the speaker I have.
Edit: I notice that this speaker has a lower freq response than any Celestion. Usable freq. range: 60 Hz ~ 4 kHz
Here is some more info http://www.peavey.com/media/pdf/manuals ... series.pdf

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Les

http://www.soundclick.com/unimind

That's why the Lead 80 came to my mind, as it has more upper end roll-off than most Celestions. Eminence's Cannabis Rex might also be a suitable alternative.

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Great tones come in small glass jars!

Updated Layout added with R10 @ 100K

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Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

Stephen, I have been following this thread but I have lost track of which version of which mod. you have decided on. Can you point me to the schematic that relates to the layout above?
Thanks
Stew

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Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

coco, in the layout, V2B cathode resistor R10 still says 56K. It should be 100K. It is correct in the schematic. Otherwise everything else looks good.

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Les

http://www.soundclick.com/unimind

fixed & re-posted

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Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

If any of you guys were wondering, I know I said I was gonna build out my V6 with the brown mods, and I did. I'm not sure if it was my speakers, my guitar, or simply just me, but I did not get the same results as Unimind got. I think it very well could simply be a playing style thing. I just dont have many EVH licks up my sleeve. I played it with the brown mods for a day, and it went back to stock plexi values. Now with the 6v6's and Stephens original plexi values, I can make the amp sing like a bird, it was just too much gain for me the other way. Sorry fellas.... Now I'm on a quest to make it louder, the journey never ends......