Planning to build a TW Express

[shipwreck]

Hello, I am new to this site, and fairly new to ampbuilding, having just completed my first working amp (a 5W Marshall-style amp from Ampmaker in UK). But already hooked.

I am thinking about ordering parts from rj guitars, who posts here. I am not going for a "vintage correct" Express, but I hope to capture some of the magical Trainwreck tone without going down the rabbit hole of hunting for obsolete parts, new old stock caps, transistors etc.

I am considering to build some sort of master volume (Lar-Mar PPIMV?), but rj guitars is suggesting that a built in attenuator is better. Has anyone compared the different methods of reducing volume for the TW Express circuit?

And there is so much info on this site that I need some help in sorting through it. Apart from the "Express build guide", what are the best sources/threads of information on this site or elsewhere? Good quality pictures will help me a lot.

And is solid core Teflon-insulated wire the best choice for most of the wiring apart from the heaters? Is there a good write up on lead dress techniques somewhere? How about soldering temperature? I have a soldering iron stations with adjustable temperature, but I am not always sure where to set it. Any good tools/techniques for avoiding overheating of components?

This is just some rambling questions, hopefully I can get more specific later on as I get ready to actually start building.

[Guy77]

Hi. In regards to the PPIMV master volume vs the attenuator (Airbrake). I tried both on my wreck build and they both sounded better than Lar Mar Type 3 master volume. I had a slight preference for the attentuator (Airbrake) over the PPIMV master volume.

In the end I felt you can't go wrong with either one , PPIMV or attenuator , they are both great sounding!
Just my 2 cents!

Cheers

Guy

[shipwreck]

OK, you don't like the "type 3" master volume? Why not? Does it sound a lot different than a "type 2"?

I liked this variant because it seems that it is the easiest one to remove from the circuit. I was thinking about wiring it with a push pull pot.




Questions (in case I should decide to go with the type 3" variant):

1. Should the master volume pot be connected to the ground buss like the rest of the pots (I assume yes)?

2. Do I need to use shielded wire between the pot and R16/R17?

[Doxie man]

That pic is just a standard cross line MV. Matchless uses that one on some of their models. It works but the Lar-Mar or TW type 2 PPIMV are much better. I pretty much always go with the Lar-Mar/type 2 when master volume is desired on my builds. It is (IMO) the best all around MV . Attenuators work well too and I like and use both.....situation depending

[RJ Guitars]

I am an advocate for the AirBrake style Attenuator because I think it keeps the tubes working hard while dialing down the volume. That is part of the magic in an Express. Lately I've been working at adding a built in attentuator circuit into my Wreck builds and so far I like it.

MV options are cheap to implement and simple to remove - try them all and see which one you like.

All of the mentioned methods for volume reduction work but I think the attenuator lets you take it down a little further before the magic fades. The magic does fade on all of them at some point but your ears are typically the only ones that you need to please. We don't all hear things the same... I kinda always thought Clapton could use some coaching on tone but somehow he sold more records than I did??

[M Fowler]

There is so much information on this site about tuning the Express that one has to spend hours going over it all. I have many times and still do.

1. Use shielded cable on input jack to 33k grid stopper on V1.

2. 820R resistor from wiper of the volume pot/shielded cable/ to V1 pin 2.

3. Use .0033 cap C8 see TAG TW Express Layout

4 Use 100k/100k not 100k/82k for on plates in PI

5.Either VVR or use a good attenuator.

Insulated input jack, no buss wire soldered to the pots, Filter caps for preamp ground near input jack. PI filter cap grounds with CT and other filter cap grounds near PT.

Watch the lead dress for the presence circuit it can be a real bugger.

[Mark]

Hi Mark

I'd have heard most of your advice apart from the 100K plate resistors in the PI stage and the quoted section. The earthing is a departure from Ken Fischer's layout, what experimenting did you do to improve upon Ken Fischer's layout?

Insulated input jack, no buss wire soldered to the pots, Filter caps for preamp ground near input jack. PI filter cap grounds with CT and other filter cap grounds near PT.

Thanks for your reply Mark.

[Mark]

Shipwreck with regard to teflon wire it is great in that the iron doesn't melt it, but it is difficult to cut (compared to PVC) which means you might cut into the wire itself and weaken it, the other thing is the teflon is very hard to bend into shape and it doesn't want to stay in the desired shape without a lot of help.

PVC is quite fiddly if you're new to soldering, but it does stay in shape and is easy to work with, till soldering. Have a think about what your needs are and buy the appropriate wire.

nd is solid core Teflon-insulated wire the best choice for most of the wiring apart from the heaters

[M Fowler]

Hi Mark

I'd have heard most of your advice apart from the 100K plate resistors in the PI stage and the quoted section. The earthing is a departure from Ken Fischer's layout, what experimenting did you do to improve upon Ken Fischer's layout?

Insulated input jack, no buss wire soldered to the pots, Filter caps for preamp ground near input jack. PI filter cap grounds with CT and other filter cap grounds near PT.

Thanks for your reply Mark.

Built several Express clones using traditional circuit including cap stack and TW grounding all as a real TW would have. The issue was ground buzz (checked cable, guitar, lights, line noise) solved with insulated input jack and have grounding near input jack not over by the cap stack. I also removed the PI filter cap grounding from preamp grounding. Presto no more annoying buzz when guitar plugged in either tele, strat or my usual a Les Paul with HB. The pots still had buss wire solderedd to back but used that as a anti-rotation option for the pots rather then as a potential ground loop source.

Mark

[Mark]

Thanks for your reply Mark, I will have to keep this in mind.

How loud was the buzz?
I assume this buzz was common to all your Express builds?

What did the two 100K plate resistors do?

[M Fowler]

The two 100k plate resistors was a suggestion I read years ago about getting the Express to play nice and quit annoying a person.

I did not notice a big difference but I did so many changes at once and did not write down an analysis of the process.

The buzz was not loud just noticeable and annoying. I knew I could rid my amps from this buzz by using a better grounding scheme.
Most of the guys I sell amps to gig and some record. I get very few recordings even though I ask for them, rat bastards.

Mark