Express Builder? - Newbie Post

[lions den]

Hello everyone, i've been lurking for a while here ever since I purchased a TW Express build from a good friend. He mentioned that someone here at TAG built the amp for him, so I thought I would take a stab at posting some pics and see if anyone recognizes it....

First off, this amp has been my go-to amp from the day I picked it up, love the ability to go from clean to mean all with the guitar volume, and still maintain a great guitar tone even at high gain.

I've tried to pick up as much information around the technical aspects of building these amps, but I'm a rookie in this area But having fun learning something new everyday.

Only issues so far have been the input jack was not shorting so when I unplugged the guitar it made an incredible humming noise. I did notice that both speaker jacks appear to be shorting type and wired in parallel, is that correct? Any advantage to having it wired this way as opposed to just the first speaker jack?

Also noticed a set of resistors in parallel right before the bias pot, that looks different from the builder guide that Ron W. put together (great document by the way), and is measuring around 22K total instead of the 47K I have seen documented. Any concerns or reasons there?

Currently running Mullard EL34's, Tungsram NOS in V1, russian made 7025 in V2, enjoying the tones quite a bit. Would like to try EI in the preamp, and maybe Siemens in the power section at some point.

Hope this link works ok to some pics, may need safari browser to view them, and I'll try to get some in the body of this thread as well.

Thanks to everyone on this board for their willingness to share information about these great amps. I'm looking forward to learning a lot more.
thanks,
sean

http://gallery.me.com/sean.joplin/100119

[Zippy]

Also noticed a set of resistors in parallel right before the bias pot, that looks different from the builder guide that Ron W. put together (great document by the way), and is measuring around 22K total instead of the 47K I have seen documented. Any concerns or reasons there?

That was likely to adjust the bias voltage range. Are you getting the correct bias voltage? If so, you're golden.

[lions den]

Zippy,
Yep no problems biasing to 40mA for the EL34's, I have not tried 6V6's as of yet.

thanks for the quick response,
sean

[Cliff Schecht]

Did it come with a Trainwreck logo put on it?

[lions den]

Yes, the only changes I have made are tubes. Logo and everything else are exactly how I received it.

[lions den]

Other question, I notice the amp has a grid resistor in V2. From reading looks like this is to tame parasitic oscillations in the tube, help reject RF on the input, or act as a high frequency roll off. But most documentation mentioned it's usually on V1. Any experience with the grid resistor in this model and why it might be on V2?
thanks,
sean

[amplifiednation]

the speaker jacks are wired in parallel but only the outside jack should be shorting. you will always have something plugged into the first jack if the amp is on, so there is no point in having it short to ground.

40mA?

[Lonely Raven]

I was hoping it was one of mine...but I solder better than that.

That said, it looks like someone tried to keep it pretty close to original.

[lions den]

40mA for a reading at one of the EL34's. That's not a good bias setting or should it be stated a different way?
Thanks
Sean

[amplifiednation]

KF said that 30mA was the magic number. It's different for every amp though--and I am no expert on bias. I think that was the "magic number" consistently using the transformers he had designed for the Express. Using the transformers that we use, that number might be different, but that is where my Express is currently set.

I'm trying to learn the "right way" to bias. I've been drinking from the amp-knowledge fire hose so it hasn't really sunken in yet. I would double check, maybe one of the guru's will jump in.

How loud is that amp?? I figured out if I attenuate about -12dB I can actually play it. Haha

Your build looks really good though. welcome to the forum

[lions den]

Taylor, thanks for the welcome message.

I had not read the magic 30mA number before. I'll play around between 30mA-40mA and see what changes.

Yes the amp is LOUD. I end up using a HO attenuator, it works well sonically and allows me to go with a wet/dry setup for effects via the line out.

sean

[amplifiednation]

Thats cool. I just powered mine up last weekend so it's new to me too and i'm learning how to use it. It's a BEAST of an amp. I was very surprised to find the cleans to be so rich. Ken did a really good job of designing the amp.

Be careful with the bias, if yours is set up differently than mine you might end up too hot and you'll have some expensive tubes red plating.

tried it with an EV 12 today with an open back and it didn't have the bass of my basketweave 412, I have been turning tubes like crazy.

[LabelBob]

Paul Ruby is your man for an Express, I have one and as soon as you fire it up you know...yep, that's the tone man, my Alessandro Red Bone hangs right with it but with a more refined voice.

Express is Sonny Corleone if you will
Red Bone is Michael

[lions den]

I normally end up playing through a Marshall 4X12 with 25 watters in it. Pushes a lot of air and the speakers are well broken in so it takes a bit of the edge off. Have tried with some alnicos and didn't care for them, the celestion G12H-30's are my second choice.
sean

[lions den]

Taylor, so the output jacks I'll call first one and second one. First one being first in line from the OT and what I normally plug the cabinet into, and second jack is the one in parallel with jack #1 and normally does not have anything plugged in.

Should it be jack 1 or 2 that is shorting? I thought jack 1 as when nothing is plugged in it puts a short across the OT and when something is plugged in the OT sees that load. If #2 is shorting doesn't that put a short across the OT in both cases where a cab is plugged in or not since it's hard wired in parallel with the first jack?

Sorry for the basic 101 question as I want to make sure I get it right.
Thanks
Sean