Starting an amp building project ('90 Kelly).

[Dyolfknip]

Hello guys!

I'm starting to build my own TW clone and wanted to ask some questions about the parts used in original units because I try to be accurate as possible. I have found already some mallory 150's capacitators and wanted to know if these are the same that Ken used (component values does match)? Also I would like to know what kind of resistors did he use? Brand of the pots & jacks? What kind of 12AX7 tubes? And last what kind of wiring did the wizard use to craft these amazing amps?

I'm planning to use Hammond transformers on my clone. Is 25W enough? I've been told that it should be enough for 50W guitar amp.

So if you have the knowlege I need to complete my clone I would be very happy i you could share your knowledge.

P.S. I have also Siemens EL34 NOS tubes wich are only siemens EL34 tubes i found (some siemens tubes can be seen on Francesca) are these possibly the correct ones?

[KennedyBlvd]

Trying to get it exactly right on the first try is a great way to start a project you'll never finish.

Cut yourself some slack on the details, get it up and running then make changes on your second try.

[Elcabong]

You should do some reading on the forum and you will find bits of information; look at the schematics and available photos. There is no such thing as an official parts list to build an exact clone of the Trainwreck; this is an ongoing process and there is still many things to learn.

Regarding the transfo. , you do not mention a part number but 25W is low. I bought my OT from Moose and it is rated at 35 w. I will use an Hammond 272JX for my PT.

[ODwan]

You should do some reading on the forum and you will find bits of information; look at the schematics and available photos. There is no such thing as an official parts list to build an exact clone of the Trainwreck; this is an ongoing process and there is still many things to learn.

Regarding the transfo. , you do not mention a part number but 25W is low. I bought my OT from Moose and it is rated at 35 w. I will use an Hammond 272JX for my PT.

The JX PT is ok. Plenty of juice there. I got good results using 1645 (5200 primary) and 1650H (6600 primary) OTs.
Have fun!
Timo

[Elcabong]

The JX PT is ok. Plenty of juice there. I got good results using 1645 (5200 primary) and 1650H (6600 primary) OTs.
Have fun!
Timo

Happy to hear that! Is it easy for you to get Hammond xfos in Germany?

[Custom 100]

Maybe check out the Hammond 1650G as well:

1650G
35 Watts
6,600 ct
200 ma.
3.5/8/16/250/500

Seems kinda like the Stancor output doesn't it? Just a thought. Good luck with the build

[ODwan]

Happy to hear that! Is it easy for you to get Hammond xfos in Germany?

Yes it is. http://www.tube-town.de is an official dealer. They offer good service and the tubeamp building forum in germany.

Timo

[Dyolfknip]

Thanks guys for the advice!

I have studied all the info (at least all that I could get. Also the pics found on forum) of this amp and asked just to be sure. I try to be accurate as i can because i know this guy who builds clones of vintage amps and therefore i got easy acces to these parts. I truly think that I never fihinsh with this clone because there is always some tweaking to be done. Or are you guys perfectly happy with your clones? Hmm. Maybe I am a perfectionist (is it spelled like that?)?

BTW. I think i'm going to use carbon film resistors & Hammond 1645 and custom made PSU.

[Humbucker]

As a newbie, I'm starting a Kelly project - actually, FOUR projects, as my friends caught early on.
We've ordered most parts and added a fan in each just to be safe. Also, the only engineer involved suggested a (switching jack activated) dummy load to prevent blow-out if someone forgets to connect a speaker cab.

We are using Uraltone TV5 (280V, more on www.uraltone.com) and Hammond 1620 transformers. The vague idea is to get a sort of LoVo sound with EL34:s.

However, I'm curious about this 1K 25W resistor. The aforementioned engineer says he doesn't fully understand the whole thing. He says it sucks everything there is to suck - here, I beg to differ.

Ken Fischer may not be a square but I think he understands tone as we mortals appreciate it. To settle this, would somebody tell me what this 25-watter does in there?

Any other advice - on Bumblebee question, perhaps? Throwing myself at your mercy...

[Elcabong]

However, I'm curious about this 1K 25W resistor. The aforementioned engineer says he doesn't fully understand the whole thing. He says it sucks everything there is to suck - here, I beg to differ.

This is a rather vague statement, for the less.

I am no expert but I would say that this resistor lowers the screen supply voltage. It also forms a pi filter with the preceeding and following capacitors. What is unusual is the relatively low value and high required wattage.

[Humbucker]

This "unusualness" made me write in the first place. 25 watts: I suspect - as a layman, as I'm not an engineer - it heats up like hell.
Would any othe value do or must it be just this: 25 watts, 1 kilo-ohm?

Pray tell me.

[doctord02]

I'd say stick with 1 k, 25 watts. It's part of the design and definitely effects how the amp behaves.

It will get pretty warm.

[Elcabong]

This "unusualness" made me write in the first place. 25 watts: I suspect - as a layman, as I'm not an engineer - it heats up like hell.
Would any othe value do or must it be just this: 25 watts, 1 kilo-ohm?

Pray tell me.

I do not have a working Trainwreck in front of me but I have seen voltage drops of 15 volts across the resistor on some schematic. If we take the rating of the PT at 300ma, we need to dissipate 4.5 watts. If you can find something at 10 watts or parallel 2 2k/5w resistors, it should be ok. But yes they will get hot. A larger wattage gives a better safety margin.

[Bear]

Check Moose's post, 2nd on this page, and other discussion:
http://maximoaudio.com/forum/viewtopic. ... 4&start=15

Bear

[UR12]

I'd say stick with 1 k, 25 watts. It's part of the design and definitely effects how the amp behaves.

It will get pretty warm.

I was reading Nik's post regarding his prototype express build. He mentioned that he didn't have a 20w and used a 10w. His remark was "Hot!!" http://maximoaudio.com/forum/viewtopic.php?t=512

So it would appear that something bigger than a 10w was needed here. I guess 25 w would be the next logical step up in rating to keep the temp down.

Having said that if you look at the schematic, the resistor is placed between two caps forming a "pi" type RC filter. It is also between the B+1 and B+2 points. B+1 connects to the CT of the OT and is feeding power to the power tubes and none of the current flowing through the Output Tubes flows through this resistor. Current flowing through the 25w resistor is going to the screen supply and the preamp tubes, and of course charging the filter caps. Unfortunatly my Express is loaned out for a gig Thursday night and I don't have it here to check voltages. It would be interesting to see how much current is actually going through this resistor with the amp cranked to 35 watts output and when I get my amp back this weekend I will measure it. I wonder also how much current flows through the 25w resistor when you turn the amp on and all of those caps are charging up. hmmmmmm