Modding my XTC :)

[gbsmusic]

Thanks Greg . That would be great indeed to become a part of Reinhold's gang, but I doubt He'd like my ideas, since they are actually quite opposite to his view on the XTC amp . He's darkened its tone and I am bringing it back to Marshall territory, with XTC "Setneck Edition" as a result .

After doing mods described above I'll record clips comparing my friend's stock XTC and my amp, using same tubes and similar settings. I am curious about the results myself .

Regards, Andy

I would love to hear the difference!!

 

[Setneck]

So, the mods are done . I changed Treble pot to linear and lowered Presence pots value to 10k. Those changes have a huge impact on amp's response. Both preamp's and poweramp's high frequencies seem to appear earlier and are more present than before. "Blanket effect" is gone completely .

Second mod was Depth/Resonance control. In place of 1M R62 resistor I installed 1M linear pot, connected to a 3-way dpdt switch, where 4n7 and 2n2 are soldered. So, I have 3 resonance caps available, those two and stock 470pF. As for now, I like 4n7 best, but even stock 470pF cap, after changing the pots sound interesting. Finally, I have full control on the bottom of the amp. Depth/Resonance control is definitely the most missing part of XTC amp.

Third mod was preamp's 1st stage mod. Some time ago I changed stock 820R//.68uF combo to 1k5//1uF. But now i decided to install a 2-way dpdt switch to have them both available. But I must say that with two above mods I started to like stock 1st gain stage values again .

Fourth mod was replacing R43 Structure resistor with .47uF ERO/Roederstein cap, in case if I'd need additional gain boost. Previously I had .68uF cap here, but it added too much bottom after engaging Structure switch. .47uF adds necessary gain kick without that flubbyness. The difference is obviously subtle, but noticeable for me.

So, it seems that it's it, as far as easy mods are concerned. Having done those mods, plus the mods done before (TAD/Mojo Dijon tone caps, 2n2 1st CC cap, 22n PI output caps, 2k7//1.5uF 2nd gain stage value) I hope that I' won;t be lost in the mix in my band anymore

In a few days I'll record some clips, comparing my modded XTC with a stock one, using the same cab, tubes and similar settings.

Many thanks to Marvel (http://www.marvelamps.com) for doing all those mods .

Some pics:

Regards, Andy

 

[gbsmusic]

This may have been explained but what is the new Marvel Mod and how is it diferent? Thanks.

 

[Setneck]

Thanks jb34_56, I just love that amp, it is great unit, but I decided to tune it a bit. Glad You fixed Your problem with =C='s, you simply can't go wrong with those tubes. I used Siemens/RFT's for a while, those are also great, but =C='s sound to my ear more complex. So during latest recording sessions of my band I switched back to =C='s.

There won't be another Marvel Mod, he's really busy making his own amps. I even had to wait for doing last mods a few months. The mod we've done to the 1st stage may be done in MM way though:
- remove white C4 .68uF MMK Rifa cap and R6 820R resistor from the pcb
- solder 820R bypassed by 0.68uF cap and 1K5 resistor bypassed by 1uF cap to the both sides of dpdt switch
- solder two wires to the mod: one wire to the center tap of a switch and second to the joined ends of the resistors
- than solder the wires to the pcb in place of R6 resistor

1K5//1uF combo gives more upper mid boost, so makes the tone brighter (more in-front), because there are less bass freqs coming out of an input stage.

Regards, Andy

 

[Setneck]

Hi!

I did short clip of my modded XTC. According to the mods, I have also removed C40 Excursion 470pF cap from the pcb and put it on the switch. So now "DEPTH" pot with the switch in "0" position is simply nfb adjustment. Which is the thing I like better than with the cap. During the recording the pot was dimed, so like in "L" position, but without the res cap.

https://www.soundclick.com/player/single ... 70472&q=hi

Here are the schems with mods marked red:





Regards, Andy

 

[Killcrop]

Seems like a lot of effort and money to go after the tones you seem to prefer on that amp. I listened to all the sound clips you posted. Why not just get a Mesa or a 5150?

Don't take offense. I'm not trying to be a dick or anything but those tones are exactly hard to come by, and for way cheaper than what a 101b costs plus mods. I guess its a free country and all.

 

[Setneck]

No offence at all Mate . Well, lots of effort, but not so much money, my tech isn't to expensive . And believe me, the tweaking process was fun itself.

You see, I just love that amp, its feel and way it responds. It sounds great itself and I wouldn't mess with it if it was my bedroom amp. But it's my main stage amp and stock it was hidden in the mix. So I had to "fine-tune" its sound, not losing Bogner flavour. We have reworked it with my tech to combine both worlds: Bogner world and my needs. You see, Esctasy is basically redesigned JMP 1959, so the idea was simple - to bring my amp slightly back to JMP territory (2nd gain stage cathode resistance, PI output caps, -fb mods). All mods were done to remove unnecessary lows, which caused "blanket effect". Now it's completely gone, although the essential thing for that was replacing dirty Treble pot with linear one (stock it's log pot).

Big part of the new sound was Mercury Magnetics transformers. I had to admit that especially output tranny brought more life into the amp. The cost of transformers was real money spent on modding, but it is worth every penny. Patrick and rest of the guys at MM did great job wounding custom OT for me, to the specs evaluated by my tech and reworked additionally by MM guys. You can even buy it now (it's called BOG-ECSTASY-O). Great piece of iron.

Why not Mesa or 5150? Both are great amps, but that's simply not my thing. Mesa is too stiff for me, I just don't feel that amp. While waiting for my Bogner to arrive I had a Tremoverb on loan, played couple of shows and didn't feel too comfortable. There's something in Mesa sound that my fingers doesn't like very much.

I also don't care for 5150 too, strange tones for me, the lows of the amp I tried were somewhat weird. In general I am not a fan of an amps which are reworked and tweaked Fender designs, with 22uF cathode bypass caps. Mesa's, Engl's - that's not my world.

Bogner is more liquid, more fluent, the notes are smooth, very soft, they just flow thru You. The feel of an amp is outstanding. This is simply my thing. I love this amp, especially now .

The only amp which inspired me since I have Bogner was Splawn Quickrod. Great amp, "rude" sound. I called him "scoundrel". I used it while waiting for MM transformers to produce. Played a few shows with it, sounded great, but I need three channels and I am not fancy messing with volume knob in my guitar to get crunch sound, I need separate channel for that. I even thought about buying QR and modyfiyng OD1 by replacing fixed dropping resistor with a pot, so it would act like second "Gain". But eventually went back to my beloved Ecstasy "Setneck Edition" .


Regards, Andy .

 

[Killcrop]

Well I hear you. I have a 101b with a Marvel Mod and KT88s. Pot, Kettle, Black.

 

[Ventura]

I just love my Bogners as is

 

[Setneck]

Lucky You Ventura . I like stock XTC as is too, but it doesn't fit my band mix. My modded amp sits there perfectly .

Regards, Andy

 

[_actual time_]

always fun to read your modding posts.

 

[Setneck]

Thanks Scott, glad that there's anyone beside me who likes that "matter" .

Regards, Andy

 

[flash6969]

My mods are designed to take away some (quite big I must say) amount of bottom, which may make an impression of taking away some chewiness and woodyness out of the overall tone also. But that Bogner flavour is definitely still there, the mods didn't make my XTC a different amp, but only a more "Marshall-esque" one.

I have a feeling that my mods have bigger impact on Red channel than a Blue, which - especially thanks to 22pF PI caps, 2.2nF CC1 cap and Mojo/TAD tone caps - is now only more close to classic JMP/JCM800 tone. But it still holds the XTC signature tone.

Regards, Andy

Some really interesting information & I'm keen to understand more about your comments- especially the "only a more "Marshall-esque" one." Don't take this the wrong way (Its an honest question) - if you want a more "Marshall-esque" tone why not buy a Marshall?

Thanks & keen to hear from you.

Cheers

 

[Setneck]

Some really interesting information & I'm keen to understand more about your comments- especially the "only a more "Marshall-esque" one." Don't take this the wrong way (Its an honest question) - if you want a more "Marshall-esque" tone why not buy a Marshall?

Well, good question . As I have said many times - I really like my amp in general. The problem was, that in my band mix stock XTC tone was hidden and blanketed. One may say - change the amp. I had a few Marshalls, still own one (6100), but I have always admired Bogner chewyness and liquidity. The feel of that amp is so unique, sometimes I had an impression that it was designed for my fingers . Other thing is that this amp is very solid and reliable. It is well designed, made from high quality materials. So, I decided to keep it and tune it.

As You may know, XTC is basically heavily tweaked JMP 1959, with added cold 10k gain stage for Red channel, as in JCM800. Reinhold's tweaks were to make that amp sounding darker. That is why it has 100nF PI output caps, 2,38k 2nd gain stage, 4.7nF 1st CC, that is why the Excursion circuit is designed certain way, that is why it has audio Treble pot. Of course, there are deeper tweaks and other Reinhold's ideas, but it is still tweaked JMP. My goal was to combine strong points of both XTC and JMP circuits. Wanted more cutting XTC, brighter and more aggressive. I was also analyzing Classic and 20th Ann circuits and tuning my amp step by step.

The essential changes were TAD/Mojo Dijon signal caps, 2k7 2nd gain stage, linear Treble pot and removed 470pF Excursion cap. So I finally ended up with an amp, which still holds Bogner tone and feel, with some "Marshall flavour", and is cutting on stage nicely, with more crunchy mids. So with the amp which is perfect for what I need .

And that is why not Marshall


Best Regards, Andy

 

[jamme61]

Some really interesting information & I'm keen to understand more about your comments- especially the "only a more "Marshall-esque" one." Don't take this the wrong way (Its an honest question) - if you want a more "Marshall-esque" tone why not buy a Marshall?

Well, good question . As I have said many times - I really like my amp in general. The problem was, that in my band mix stock XTC tone was hidden and blanketed. One may say - change the amp. I had a few Marshalls, still own one (6100), but I have always admired Bogner chewyness and liquidity. The feel of that amp is so unique, sometimes I had an impression that it was designed for my fingers . Other thing is that this amp is very solid and reliable. It is well designed, made from high quality materials. So, I decided to keep it and tune it.

As You may know, XTC is basically heavily tweaked JMP 1959, with added cold 10k gain stage for Red channel, as in JCM800. Reinhold's tweaks were to make that amp sounding darker. That is why it has 100nF PI output caps, 2,38k 2nd gain stage, 4.7nF 1st CC, that is why the Excursion circuit is designed certain way, that is why it has audio Treble pot. Of course, there are deeper tweaks and other Reinhold's ideas, but it is still tweaked JMP. My goal was to combine strong points of both XTC and JMP circuits. Wanted more cutting XTC, brighter and more aggressive. I was also analyzing Classic and 20th Ann circuits and tuning my amp step by step.

The essential changes were TAD/Mojo Dijon signal caps, 2k7 2nd gain stage, linear Treble pot and removed 470pF Excursion cap. So I finally ended up with an amp, which still holds Bogner tone and feel, with some "Marshall flavour", and is cutting on stage nicely, with more crunchy mids. So with the amp which is perfect for what I need .

And that is why not Marshall

Agree 1000% thanks for all the info you have posted.

 

[Setneck]

Agree 1000% thanks for all the info you have posted. It's helped me and I'm sure a lot of other guys out there.

No problem Mate, always glad to help Bogner brothers . So anyone, always feel free to ask any questions .

Regards, Andy

 

[Setneck]

Modding is more than addiction, it's like bad habit . Further mods done in Marvel Amps HQ:

- raised back 1st CC to 4.4nF, soldering 2.2nF cap in parallel with present 2.2nF. The sound became a bit more beefy, not losing clarity. 2.2nF sounded too dry
- installed modified PTP Marvel Mod, where in "Cameron" voicing 1uF cap was replaced with .68uF. Slight boost in gain was a goal, but 1uF cap was bringing too much lows. .68uF is just right. That is a modification invented by Brent from Bogner Amp Forum
- installed 4th gain stage cathode bypass mod with a switchable 1uF and .68uF caps. I did it "just in case", to use it mainly in studio. That mod is especially great for boosting Blue Channel or Plexi Mode (don't like it with Red, where redesigned Cameron shines better)

NOS MKT1813 & MKT1822 ERO/Roederstein caps was used exclusively for bypass purposes, TAD/Mojo Dijon mustard clone was used for additional coupling.

Few pics:











Regards, Andy

 

[_actual time_]

installed modified PTP Marvel Mod, where in "Cameron" voicing 1uF cap was replaced with .68uF. Slight boost in gain was a goal, but 1uF cap was bringing too much lows. .68uF is just right. That is a modification invented by Brent from Bogner Amp Forum

cool. that is next on my list. i've got the MKT cap and will build a little circuit board, like Marvel's.

installed 4th gain stage cathode bypass mod with a switchable 1uF and .68uF caps. I did it "just in case", to use it mainly in studio. That mod is especially great for boosting Blue Channel or Plexi Mode (don't like it with Red, where redesigned Cameron shines better)

let us know what you think, on your second try with this R19 mod. i like it on Blue, mostly unboosted Blue. i also like it on unboosted Red, for a different sound than just boosted Red. but yes, R19 + boosted Red for me is too much.

i think "just in case" is exactly the way to say it--it's a different choice, for people like me who need too many choices.

cool pics! you removed the FX send level knob, just so you could put in more mod switches?

 

[Setneck]

let us know what you think, on your second try with this R19 mod. i like it on Blue, mostly unboosted Blue. i also like it on unboosted Red, for a different sound than just boosted Red. but yes, R19 + boosted Red for me is too much.

I must admit that I like it very much with my modded amp. Stock it wasn't satysfying, as there was too much compressing lows in the tone. Now my Blue with last stage boosted with .68uF cap truly sounds like hot-rodded JMP - which basically my Blue channel became after the mods done to 2nd gain stage, PI output caps, tone caps and nfb circuit.

Currently I have my Bogner at home and play only Blue R19 boosted. Insane classic Marshall tones, Bogner flavoured .

i think "just in case" is exactly the way to say it--it's a different choice, for people like me who need too many choices.

Same with me, I won't use R19 mod on stage but it is cool to have that option for studio purposes.

cool pics! you removed the FX send level knob, just so you could put in more mod switches?

I have removed Line Out Level Control for R19 mod as I don't use this feature.

 

[pedal builder]

What would you say is the most effective/useful mod you have done aside from the recap.