Finally finished my TWreck Version A4!

[ricks57custom]

Hi all,
I just that everyone who helped answer my questions. I've got to shout it out to you guys because most people don't care or know about these amps. I'm going to post clips and pics very soon but I wanted to give my first impressions and ask a couple of new questions from you guys.

After a few wiring tweaks (suggested by a good friend who is far more expereinced than me) and replacing a faulty power tube that had me confused and pissed off, the amp was ready to try last night. I plugged it in to a 4X12 with greenbacks and proceeded to play. These were my first thoughts: Warm, responsive, good EQ parameters (unlike a Marshall), punchy and brash but not ice-picky, not too trebly. Overall, it felt like a blackface Bassman Head with a hair bit more gain. I installed that "easiest master mod" replacing the 1M resistor with a pot and didn't love the outcome. It didn't come alive until 5 or six and before that it was not giving up the power tube gain. By that time it's really loud! Also, even on 0 the volume bled through. I'm going to try a different master in there when I have a chance. Maybe the PPIMV.

I think it sounds great and it will take time to fully know what I want and don't want from the circuit, tweakwise. I was surprised that it didn't have a bit more gain. After listening to Loverockers clips, I expected more. I was wondering if there were tweaks to the circuit to add a bit more saturation. I don not have a 500/100pf swith and I'm wondering if that adds a bit of bite. Any suggestions about tweaks to Version A4 to give it more gain?

Overall, I am very happy with this build and can't believe I got it from schematic to reality. I am really happy that this site exists. Thanks for taking the time to read.

[loverocker]

Congrats! Though if I did any clips, I must've done them in my sleep! Because I've been trying on and off to get happy with an audio interface for weeks and still haven't managed it

Weird about not having enough gain for you, though? Compared to my BF Fender (an old Bandmaster) - my semi-Liverpool has a *lot* more gain. More also than a typical non-MV Marshall, too. I wonder if there's a wiring/soldering SNAFU holding your amp back?

[ricks57custom]

Loverocker,
Sorry, I meant Geetarpicker.

I have yet to really put it through it's paces and maybe the master I have in there is clipping some gain off the signal. I've gone through the layout several times and I'm pretty sure it's correct. But it may be that this version has less gain than others. Anyone have any thoughts about Version A4 opposed to Version A1b?

[Elcabong]

Congrats Ricks57custom.

The main differences between A4 and A1b are the 47K and 820R grid resistors on the first and second stages. Also the 150K plate resistor used on the second stage should translate to more gain, but the following grid leak resistor is smaller, 56K vs 150k for the A1b, probably compansating.

The PI and power amp are pretty much the same.

You could try to short out the grid resistors and see how the amp manage. What values have you used for the treble and bass pots?

[ricks57custom]

Elcabong,
I was told that the 47k and 820 resistors don't actually affect the gain stage as much as stabilize oscillation (which I had none of). What's your take on them?

Also, do you think upping the grid leak resistor to .002 could make it growl a bit more? What about reducing the negative feedback resistor to 47k and running from the 8ohm tap? I was also told that lowering the second 2k7 cathode resistor a bit could add some gain.

BTW, my treble pot is 250kA and my bass is 250k. I've read about using a 1m for the bass but I don't feel like mine is missing low end.

I am going to disconnect the master and see if that's affecting the power tube distortion at all. Thanks for the comments.

Rick

[Elcabong]

Rick,

The reason I mentionned the 47k and the 820 was that they are not included in all versions. I am puzzled by the exact role of the 820, with such a low value; the designer probably wanted minimal impact.

I guess you meant upping the coupling cap to .002. This would mean some more bass response; you can give it a try.

Lowering the second stage resistor will increase the gain but will also affect the dynamics as the Q-point is lowered; the lower part of the signal will clip at some point.

Where can I listen to the Geetarpicker clip? Is he playing an A4 version?

One last thing. What type of guitar/pickup are you using?

[markd]

Also the 150K plate resistor used on the second stage should translate to more gain, but the following grid leak resistor is smaller, 56K vs 150k for the A1b, probably compansating.

Ricks57,
Like the man said, the grid resistor following the second gain stage is in parallel with the plate resistor of the second stage when figuring the gain of that stage. Also, as mentioned, your problem may be a wiring snafu. But if not, you could increase the gain of the preamp by increasing the value of that 56k grid leak resistor. Try a 100k first. That grid resistor could be as large as 1M, but I'm sure you will get enough gain without going that big.
That grid leak resistor also forms a high pass filter with the coupling cap just before it. Increasing the grid resistor value will shift the shoulder frequency of that filter down. So increasing the grid leak resistor's value will increase the low end without increasing the value of the coupling cap. So just try changing the value of one component at a time. You should get the gain you want, and more low end, by just adjusting the grid leak resistor to a higher value. If you want more low end after that increase the .001 coupling cap to .002.
hth, markd

[geetarpicker]

Geetarpicker here. My clips were done over a decade ago, with a real Express. 1st clip is a Les Paul > Express > 25 watter greenback 4x12. 2nd clip is a frankenstrat > Express > 30 watter blackback 4x12. Both clips have some Yamaha reverb (SPX900) added during mixdown, but no inline pedals were used. These are the only two I have uploaded, hopefully I'll get around to posting more soon.

Both clips have the amp volume around 1pm on the dial, with plenty of gain still left if needed. My Express has so much gain I rarely ever need to dime it. It actually sounds best around 12 to 2pm on the dial.

Congrats on getting your clone up and running!

http://www.starlaser.com/nicegear/burstsample1.mp3

http://www.starlaser.com/nicegear/wrecksample1.mp3

[Elcabong]

Thanks for the info, geetarpicker. I heard the clips before but did not know the author. The one with the Les Paul is really great! The playing and notes choice, the increasing intensity makes this one stands well over average.

[ricks57custom]

Thanks for the help guys. I'm going to disable the master and see where my gain is at before trying the changes. It may be something that simple. I will let you know my findings and report back with pics and soundfiles. I appreciate the help and suggestions.

Geetarpicker, that's a sound I'm trying to aspire to. Don't think I'll get there but it never hurts to think big.

[glasman]

Thanks for the help guys. I'm going to disable the master and see where my gain is at before trying the changes. It may be something that simple. I will let you know my findings and report back with pics and soundfiles. I appreciate the help and suggestions.

Geetarpicker, that's a sound I'm trying to aspire to. Don't think I'll get there but it never hurts to think big.

Rick,

I am getting ready to start a Wreck project. Would be fun to compare notes as we are in the same area (I am in Mesa). If interesting drop me a note at glasman@cox.net.

Thanks
Gary

[ricks57custom]

Got to really turn it up last night and see what it can do. WOW! It has BALLS! The master is really not very good. I couldn't get any power am distortion with it. I'm definitely putting in a Post Phase Master. It has good bottom end, glassy highs, very senstive EQ, and each guitar sounds like itself. That's what I think I like the most about it. I've got to post some clips and pics soon. I am very happy with my "knockoff".