[dukeamps]

Hi

I am using resistors ... did you place the diodes between center tap of the PT and ground (so CT gets "removed" from ground)? Or do you place them - as some people advice - between B+ and anodes?

Regards, Dietmar

Hi Dietmar, I'm still waiting for them to come in the post. The amp that I have posted here has a Trainwreck express power transformer in it, & that has already a lower b+, say a normal jmp 50w have 440v on pin 4 of the power tubes & that amp has 390v. Check your voltage on pin 4 of your power tubes & see what that measures.

I'm still trying to figure out where to put these zener diodes, I have read the negative side of the bridge rectifier to ground works. I have also read that with resistors you can get to much sag.

Cheers

Nigel
 

[Stone]

Hi

Tried lowering B+ with resistors and it was working quiet well, but I have to say that I only lowered B+ of the triodes and not of the EL34; at plates of the power amp section I can measure about 420 volts ... I think lowering to 390 will give that extra crunch while biasing a little too hot.

Unfortunately I cannot make any recordings which will be of a good quality, because I can record with my camcorder only and even if I connect a Sennheiser mic to it, it just distorts the sound.

I will try to make some recording with "room sound" - maybe it lowers the input level.

At least I raised B+ again to its original specs I noticed nearly no change, so this seems to have a major effect on power tubes.

Regards, Stone

[dukeamps]

Hi

Tried lowering B+ with resistors and it was working quiet well, but I have to say that I only lowered B+ of the triodes and not of the EL34; at plates of the power amp section I can measure about 420 volts ... I think lowering to 390 will give that extra crunch while biasing a little too hot.

Unfortunately I cannot make any recordings which will be of a good quality, because I can record with my camcorder only and even if I connect a Sennheiser mic to it, it just distorts the sound.

I will try to make some recording with "room sound" - maybe it lowers the input level.

At least I raised B+ again to its original specs I noticed nearly no change, so this seems to have a major effect on power tubes.

Regards, Stone

Hi stone, Have you tried this mod? It would be nice to hear how your amps sounds. I think you have to lower both the power & preamp tubes to get that crunch. On the power transformer i have used, i have 3 taps 240v= 385v, 230v= 400v, & 220v= 415, the 240v with 385v on the plates sounds the best.

Cheers

nigel

[Stone]

Hi Nigel

Surprisingly I did some recordings with "room sound" which come close to what you will hear live .... have a look at http://mirror.stones-amp-inn.de/evh.mpg and let me know. You will see me bright caps switching with switches on the back of the amp btw.

The cab is loaded with V30s and Craaft Speaker, which give a little smoother top - a little bit contrary to the sound being hunted. The guitar is a selfmade Strat, as shown on TT Forum meeting in September, loaded with a GFS Fat PAT at bridge and a Rockinger Blade Screamer at neck - the neck itself is a Warmoth one (boatneck), full scalloped.

The aspect ratio of the video does not fit (must be 16:9, not 4:3), but I think you won't hear the difference Just kidding. And no, it is not my kitchen, but my amp cooking room




Regards, Stone

[dukeamps]

Hi Nigel

Surprisingly I did some recordings with "room sound" which come close to what you will hear live .... have a look at http://mirror.stones-amp-inn.de/evh.mpg and let me know. You will see me bright caps switching with switches on the back of the amp btw.

The cab is loaded with V30s and Craaft Speaker, which give a little smoother top - a little bit contrary to the sound being hunted. The guitar is a selfmade Strat, as shown on TT Forum meeting in September, loaded with a GFS Fat PAT at bridge and a Rockinger Blade Screamer at neck - the neck itself is a Warmoth one (boatneck), full scalloped.

The aspect ratio of the video does not fit (must be 16:9, not 4:3), but I think you won't hear the difference Just kidding. And no, it is not my kitchen, but my amp cooking room




Regards, Stone

Hi stone, sounds like you have a nice crunch going on there, What are the specs on the amp?

cheers

Nigel

[Stone]

Thanks, Nigel.

Yes, it sounds like crunch, which is a little bit richer or even fatter than usual, but the cam adds a little bit of compression to it and eats a little bit of the bite on top of the sound, but not that much as expected. Maybe the cam is much closer to the sound than my own impression and the effect is based on the Craaft speakers - which I play them for ...

The specs are rather easy ... I reversed your setup in a way and changed some values: 1st 100k:10k|220µF, 2nd 100k:2k7|.68µF, 3rd 100k:3k3|220µF. In between the stages I am using 500pF bright caps and the usual voltage dividers, but the "upper resistor" acting as grid stopper.

2nd anode is bypassed by a 500pF cap, but I am not sure, if this too much and I think I will give 250pF down to 50pF a try; also I added a cap to anode/grid of first stage, 100pF value, but this seems to be too high, too.

Tone stack is stock. 33k and 500pF, 25k pot for mids. Setting is gain 4, treb 5, mid 10, bass 5, pres 5, mv to around three and a half (log 1M pot).

B+ must be rather high, as I removed my "lowering" resistors.

Regards, Stone

[dukeamps]

Hi stone, i have tried the 10k on v1 & found that you lose too much gain. The 220ufs are they not too high? Try the shield trick on the input cable see what you think of it. Here's how its done again, your shield cable has an outer core that usually goes to ground, just put that on the anode of the first tube & don't connect the other side to anything, it takes so much noise away.  Here's a pic, its not the best  but you can see how its done. http://picasaweb.google.com/Stratocaster64/Plexi02?authkey=Gv1sRgCNi9_dnO2oj2Vw#5354732783598173362 these are pics from a Tim Caswell modded amp.
I have actually tried this mod & it sounds very good. Have to do some recordings next week.

Cheers

Nigel

[Stone]

Hi Nigel

Actually I did not use any shielded cable within the amp (will give it a try) as I did in all the others, because it was stock before starting to modify it. The 10k reduces gain, that 's true, but taken as v1 it acts like a booster in front of the treble channel of an 1959 (also I did not use the 2n2 coupling cap of that channel).

On the other hand side the 3k3 on 3rd triode does also reduce the gain a bit, but I think it makes the crunch sound even harder than using a 1k or 820 ohms resistor and the next stage is the cathode follower.

The 220µF are a choice of what I had to hand, because one of the #34 specs I found stated 330µF. You can go down to 100µF, which will give you the same bass response - I think the 330µF are related to the original 330µF | 820 ohms cathode of a 1959.

Has been a long time ago I was on the run for Eds sound, but now it was more a product by random

I was seeking for #34 mod schem and found those different specs for it - tried the first one and found that it comes close to what is called "brown sound". And as I said, Ed himself altered his sound during the albums, so - to my opinion - it is hard to speak of "that brown sound" ...

Most people refer to VH-I as brown sound, which comes close to your modification and sound example. I do prefer the later albums and songs, where the sound became more crunchy and less saturated.

Hard to explain ... "mean street", "somebody get me doctor", "Romeos delight" and "girl gone bad" are my favorite songs. And most of the times I was seeking for Eds sound I referred to those songs.

Let 's  see where this journey takes me

Regards, Stone

[dukeamps]

Hi stone, really like that evh tone, I was just listening to the songs on youtube. I have also seen that sche with the 330uf, I don't believe that, I think that’s what Tim Caswell said to confuse everyone, but I could be wrong

If you try that mod post a clip to compare it with mine.

Cheers

Nigel

[Stone]

Hi Nigel

I think I will stay with that fat crunch at least, but I will give your mod a try (maybe without lowering B+) and see if I can make a recording next days.

Regards, Stone

[dukeamps]

Hi Nigel

I think I will stay with that fat crunch at least, but I will give your mod a try (maybe without lowering B+) and see if I can make a recording next days.

Regards, Stone

Hi stone, sounds good:) I have also that mod in my other 50w amp without lowering the b+ & it has a real good rock tone.

It would be nice to hear how yours sounds too.

Cheers

Nigel

Ps it could be that with the higher b+ the 1000pf bright cap is too much.

[Stone]

Hi Nigel

Done ... but it is loud as hell - it was before, but this must be hell²  The sound is too loud as that I can make any recordings / videos with an appropiate quality - will try this next days with a power soak / brake. 

There is not much difference, I think: my 2204 sounds harder which must be because of higher B+ and maybe because of OT (which is a Drake / Marshall). I used a 250pF across second anode resistor which lowers the highs but not that much - even the fizzle is gone (47pF as PI anode cap).

It reacts much more to harmonics like the c, b played in "ain't talking" after the a, g chords.

Maybe I had a bad solder before because of its volume now, I have to look for it - it is not possible to play it for about half a minute On the other hand side, even if there are average voltages stated within the Marshall schematic, I got 60 volts more on the plates than stated (425 volts instead of 365) and I do not know why.

Hm ... I will have a closer look to the PT and its wiring.

Regards, Stone

[dukeamps]

Hi Nigel

Done ... but it is loud as hell - it was before, but this must be hell²  The sound is too loud as that I can make any recordings / videos with an appropiate quality - will try this next days with a power soak / brake. 

There is not much difference, I think: my 2204 sounds harder which must be because of higher B+ and maybe because of OT (which is a Drake / Marshall). I used a 250pF across second anode resistor which lowers the highs but not that much - even the fizzle is gone (47pF as PI anode cap).

It reacts much more to harmonics like the c, b played in "ain't talking" after the a, g chords.

Maybe I had a bad solder before because of its volume now, I have to look for it - it is not possible to play it for about half a minute On the other hand side, even if there are average voltages stated within the Marshall schematic, I got 60 volts more on the plates than stated (425 volts instead of 365) and I do not know why.

Hm ... I will have a closer look to the PT and its wiring.

Regards, Stone

Hi stone, yes with all that boosting it will blow your ears off Did you try the shield trick? also if you have too many highs put the 500pf on the first 100k plate resistor instead of the second. What bright cap did you use? How do you like that mod?

Cheers

Nigel

[Stone]

Hi Nigel

I will try it with a soak - I modded my 2203 to #39 specs and it has less volume; even with mv set to 2 (and it 's a log pot) you have the impression the amp is turned up to 10.

I am using a 470pF across the 470k which comes right before gain (gain is bypassed with 1nF) and left the 470k / 470k following voltage divider unpassed, only the 250pF across the 2nd anode. Cathodes are 2k7 || 680nF, 10k || 1µF, 820 || 680nF. All anode resistors are 100k.

I left the 100pF anode to cathode cap on the first stage and the mod is sounding very "versatile" to me - smooth highs with a little sparcle on it but without getting too thick, I would say ... I got the impression that the missing 470pF on the 470k voltage divider normally gives a certain amount of fizzle - but not sure about that.

How do I feel about that mod ... ? To be honest: it makes me love them Marshall beasts again I have been playing Marshalls for a long time and I think most of the newer ones are missing character, sounding too smooth etc. I always stick to the master volumes but at least I was unhappy with them because being too harsh and inflexible, that 's why I tried that #39 mod (and tweaked it later on).

I think I will give a try on next Monday while practicing with the band.

Regards, Stone

[dukeamps]

Hi Nigel

I will try it with a soak - I modded my 2203 to #39 specs and it has less volume; even with mv set to 2 (and it 's a log pot) you have the impression the amp is turned up to 10.

I am using a 470pF across the 470k which comes right before gain (gain is bypassed with 1nF) and left the 470k / 470k following voltage divider unpassed, only the 250pF across the 2nd anode. Cathodes are 2k7 || 680nF, 10k || 1µF, 820 || 680nF. All anode resistors are 100k.

I left the 100pF anode to cathode cap on the first stage and the mod is sounding very "versatile" to me - smooth highs with a little sparcle on it but without getting too thick, I would say ... I got the impression that the missing 470pF on the 470k voltage divider normally gives a certain amount of fizzle - but not sure about that.

How do I feel about that mod ... ? To be honest: it makes me love them Marshall beasts again I have been playing Marshalls for a long time and I think most of the newer ones are missing character, sounding too smooth etc. I always stick to the master volumes but at least I was unhappy with them because being too harsh and inflexible, that 's why I tried that #39 mod (and tweaked it later on).

I think I will give a try on next Monday while practicing with the band.

Regards, Stone

Hi stone, what type of mv are you using?

Nigel