First Amp Build - TW Express Kit Results

[Winder]

Posting in case this might help someone. Decided my first full amp build would be a TW Express Clone (learning/tweaking on an 18W “Plexi” for about 6 months prior). Purchased a kit from RJ in August. First picture below is a gut shot of the build, completed in November. Note: I had to swap OT primary wires.

[img830]http://www.highorderpickups.com/Gear_Pa ... 20Done.jpg[/img]

First run sounded great … second and beyond were pretty bad (harsh, sterile, raspy). I’ve experienced this before, which is why I’m trying to learn about amps and how to fix such things. My whole rig went to $h@t about a year ago and I haven’t been able to enjoy it since. Really depressing. With this build, I think I’m on my way back.

Figured the issue here was parasitic oscillation. In the picture below, I rewired a few areas to more-or-less mimic Francesca (not 100%, but …). I was surprised that this brought the amp back to life (that in itself was a learning point). Even though I consider my original wiring fairly tight, it didn’t “sound” good. I rewired in phases, and rewiring V1 had the most impact – maybe all of it. That said, there was still a substantial amount of fizz … most noticeable through a 1x12 w/Scumback M75 … a bit less through a 4x12 w/G12-65 and half a 4x12 w/G12-H30 (I like the G12-65 best – these are circa 1980). All around though, high notes sounded a bit thin and “funny”.

[img896]http://www.highorderpickups.com/Gear_Pa ... Wiring.jpg[/img]

In the picture below, I added a 15K grid stopper to V1b and an 820 ohm to V1a … closest I had to “Ingrid” values, as near as I can tell. This is much better. The “funny” is all but gone from the high notes (might could be a tad richer) and the fizz is currently tolerable with the G12-65s and G12H-30s. The Scumback just seems to emphasize the fizz that’s there … odd, but maybe it provides the benchmark for “fizz-free” if I can achieve that (not sure I need to)? I plan to experiment a bit more with grid stoppers.

[img896]http://www.highorderpickups.com/Gear_Pa ... oppers.jpg[/img]

I will say that, current fizz aside; this is shaping into one of the best sounding amps I’ve ever played through. Overall, the amp is pretty righteous for what I’m after which is classic rock to VH-1 tone. Don’t play clean too much, but it seems fine there. I just purchased an Apogee Duet, so I hope to learn how to capture decent clips within the range of my limited playing skills.

I would recommend the RJ kit. It came complete, and with quality components. I believe the parasitics can crop up in any build and are not specific to this or any kit – the amp is quiet and I can dime it without any other issues. With the tweaks noted above, my vintage Marshalls and other amps may start to gather a lot of dust.

FWIW. YMMV. Etc. Here are a couple of additional pictures. For obvious reasons, I probably won’t hang here. I will answer PMs and would be happy to try to help anyone to the degree that I can, based on my limited experience thus far.


[img896]http://www.highorderpickups.com/Gear_Pa ... Supply.jpg[/img]

[img896]http://www.highorderpickups.com/Gear_Pa ... 0Wired.jpg[/img]

[Colossal]

Beautiful build! Very clean.

[Richie]

That is a super neat clean build I see you reversed the plate wires on V1. from the first pic.
And the chassis can be different and depending on which one you use,or what you are going after. A close clone or one that does not have to be exact.
Some you may have to drill for the bottom plate you use. Some have board mounting holes,some don't,some have transformer holes some don't. And the reason is, people may use something different, and want to make their own mounting holes. Others are predrilled for certain boards etc. I still think a good feature for the express is to add the bias pot,and test points. Then you don't have to remove the amp chassis from the cab, and remove the bottom plate etc. Changing a set of tubes and rebias just takes a few mins.

[M Fowler]

Well executed build I'm impressed with your neatness.

[roberto]

Really impressive! Neat and clean.
Good job!

[Mark]

Beautiful build, excellent workmanship. Regarding parasitic oscillations in the amp. Prior to putting the 820 ohm resistor in, how did the volume control operate, were there any strange noises from it?

While many pictures show Ken Fischer didn't use shielded cable for the wiper, I've found the wiper connection to be very sensitive and in some cases more sensitive than the input.

[Winder]

Mark,

I don't recall any strange noises from the volume pot. Originally, I had a shielded cable here. After experimenting a bit over the last few days, I'll probably go back to that. Thanks.

[Mark]

Check out how Dave Funk uses shielded cable in this Liverpool amp. The shielding of the cable is soldered to the plate of the triode affected and the signal wire goes to the 820 ohm resistor and not the grid connection of the valve. I've tried it and it does work, it doesn't seem to effect the tone of the amp and it is suppose to kill high frequency oscillation.

https://tubeamparchive.com/download/file.php?id=27366

BTW make sure you use heat shrink to stop people touching the shield if you do use this idea.

[RJ Guitars]

Winder, Nice amp build and thanks for the kind words. You've work quality looks great. Plus, you've done yourself a favor to keep everything tidy. That is one area where this amp tends to punish folks if they don't get things just right.

I always try to encourage folks to think of my offerings as parts packages rather than kits... a kit might imply it comes with instructions or tech help. I generally allow for a bit of DIY left to accommodate the individual preferences of each builder. I don't mind giving away what I know but there are many more informed experts above what I can offer. This forum is really the brain trust for putting together a good Wreck build.

Thanks for sharing the build info and the great photos. Each time one of these is posted up we all gain a little more understanding of these amps.

[Zippy]

I always try to encourage folks to think of my offerings as parts packages rather than kits... a kit might imply it comes with instructions or tech help. I generally allow for a bit of DIY left to accommodate the individual preferences of each builder. I don't mind giving away what I know but there are many more informed experts above what I can offer. This forum is really the brain trust for putting together a good Wreck build.

Don't sell yourself short, RJ. If Ceriatone qualifies as a kit, your Box o' High Quality Parts certainly surpasses the accepted standard.

A rose by any other name...

All the best to you and yours in the new year,

George