20th Anniversary XTC Details?!?!?

I know the circuit has some cap types and values changed but does anyone have specifics? IE C17 changed from ___ to ___. Any inside gut shots as well?

Bogner has redone the amp quite a lot. Here are some basic data.

First of all, 1st and 3rd coupling caps (C1 & C14) values has been changed to 10nF (101B - 4.7nF) and to 2.2nF (101B - 22nF). Doing that he let lows coming earlier into the circuit (more n's in CC - more bass going thru) and cut them out after the last gain stage (remember that the last stage is present only in Red).

He also increased 2nd stage's grid stopper from 500K to 1M and added 330K voltage divider resistor before that, with added 2nF cap before added 1M grid stopper. 101B's 499K grid stopper resistor bypassed by 470pF cap (R112//C112) became a treble-peaker like in 1959/2203.

Also 470pF bypass cap from 3rd stage's grid stopper has been removed

The 2nd cathode was changed from 2.38K to 2.7K (bypass cap remained 1.5uF tantalum), also Structure circuit was removed. Bogner also removed cold gain stage, changing 3rd stage's cathode from 10K to 2.7K, bypassing it also with .47uF electrolytic cap.

4th cathode 1K is now bypassed with switchable 1uF marked Vintage/Modern (the switched is placed where Structure switch in 101B is)

Plexi Mode values has been changed from 499K//470pF to 2.2M//100pF

B1 & B2 was reworked from 470pF|4.7nF to 150pF|1nF (more highs)

I think that NFB circuit and Excursion was changed, but I don't know the values. Poweramp filtering is in Classic values.

Also read those topics:
viewtopic.php?f=59&t=71083
viewtopic.php?f=59&t=114618

Regards, Andy

Andy,

Thanks for the info! That is a great help. Basically I'm tinkering with a '96 101B and may try some mods to get closer to a 20th as well.

Thanks again, Rob

You're welcome Rob.

Actually it might be difficult to mod the 101B to 20th Ann specs. You'd have to rework the whole amp, not only preamp but the poweramp too (different filtering, nfb circuit).

If You want more open tone You may try some of my mods:
- 1st stage: 1.5K//1uF - NOS MKT1813 bypass cap
- 2nd stage: 2.7K//1.5uF - NOS MKT1813 bypass cap (this stage is the same as in Classic/20th Ann)
- Structure R43: 12K - giving 2.2K overall resistance in 2nd stage if needed (C2 removed) - actually You may remove Structure circuit totally
- all dirty CC's and dirty tone caps changed to TAD/Mojo Dijon film-to-foil caps (partially similar to 20th Ann where TAD's and Sozo's were used)
- 1st dirty CC: .0022uF
- PI output caps: .022uF (Mallory 150)

In this thread: viewtopic.php?f=59&t=116020 You'll find some samples and caps descriptions.

Regards, Andy

Hey Andy,

i would like to ask you if there have been different revisions of the XTC20th 6L6 amp and which what are the differences (nir esp. in components but in tone)? I would like to buy a used one, but want to be sure that its a newer revision. I´ve heard that some newer Sozo caps were being installed from end of spring 2014. Is this true?

This past spring ('14) the newest generation of Sozos started getting used. Charley says that the whole team liked the new ones better.

I just finally sold a 20th XTC 6l6 after having it listed on and off for 2 months, great amp that I had for a little over 2 yrs. But honestly if you buy the amp for the blue channel as many people do and prefer it, do yourself a big, big favor and stick with a regular el34 101b. Way better imho.

sjk":3v287n59 said:

I just finally sold a 20th XTC 6l6 after having it listed on and off for 2 months, great amp that I had for a little over 2 yrs. But honestly if you buy the amp for the blue channel as many people do and prefer it, do yourself a big, big favor and stick with a regular el34 101b. Way better imho.

Click to expand...

Got you. Thanks. Will think about it.
What do you play now?

SJK, you are probably right for most. I find myself at 10:00 on the gain for both Blue and Red on the 101b and that is the why the Blue and Red on the 20th were great for me, as that is right in that amp's wheelhouse.

Went with the EL34 version of the 20th.

Never selling it.

Ever.

sjk":2r2c6kq8 said:

I just finally sold a 20th XTC 6l6 after having it listed on and off for 2 months, great amp that I had for a little over 2 yrs. But honestly if you buy the amp for the blue channel as many people do and prefer it, do yourself a big, big favor and stick with a regular el34 101b. Way better imho.

Click to expand...

Plus 1000% still a little bitter selling my 101b to buy the 20 th so I could lose more money when I sold it to buy back my 101b

I have 2004 101b. I bought 20th 6L6 ver.
20th has better loop (perfectly transparent), much nicer clean channel and boost on it just make it louder and not changing the sound (as it should be). More gain that sings and sings and sings! is nice end even and just beautiful. I think Excursion switches are tuned differently unless they just react this way on the new preamp - all is nicely tuned though.
20th unfortunately does not have the same CHARACTER on the 2 & 3 channel. It is different amp. It is Bogner but different. I send it back. I like 101B more although clean and loop is ''much worse'' than on 20th. I would ask Rainhold to build 101B with 20th clean channel and loop and two master volumes. It would be just PERFECT.

I wonder how 20th EL34 ver compares with 101b?