The Steel Guitar Forum

Help,
I hope you guys, who have used a 9002 TubeWorks RealTube2 can help me.
I just received a brand new RealTube2 w/steel-mod. To test it, I'm using a Nash400 and the preamp only. I plugged my guitar into the preamp. Then I came out of the pre-amp on the "Line (0dbm) A mono" just like the instructions said, into the back of the Nash where it sais poweramp in. (Just like peavey said. I have a horrible low frequency hum on channel 2 (the clean channel) only??
Now if I use the "INST -20dbm" line out on the preamp. I do not get a hum.
Does everyone elses do this on the 0dbm line??
The instructions say use 0dm for power amps, and -20dbm to plug into the front of a combo amp.

Help, Help before I send this thing back to Arizona to have them check this out.

Thanks to all.


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Jason (Slyde) Ory
Cullman, AL
Franklin D-10

If both the preamp and the amp have grounded AC cords you will get hum. Try a ground lift adaptor on the preamp AC cord, if it is a 120VAC plug-in unit (I assume it is, due to the plate voltage requirements). The guitar cord that connects the preamp to the Nashville is grounding the two units together and this will produce ground loop hum, lifting ground at the preamp gives it a ground path throught the Nashville 400 only. Ideally you need a one to one transformer interface to isolate the chassis grounds, thus allowing the units to be properly grounded with their respective AC cords.
I checked the specs on the Nashville 400, power amp input. It is rated 0 dBV, 1 volt RMS and 22 K ohms input impedance. This should be a good voltage and impedance match for your unit. This is an unbalanced input (signal path used shield for signal transfer), hence the hum problem. I could not find that the output of the Tubeworks product was unbalanced (Tip, sleeve) or balanced (tip, ring, sleeve)in their online manual. If it is a balanced output, a cord can be made/bought to solve the ground problem. Tranformer isolation and proper ground seperation should cure this in the long run, too.<FONT SIZE=1 COLOR="#8e236b"><p align=CENTER>[This message was edited by Ken Fox on 05 December 2002 at 08:22 PM.]</p></FONT><FONT SIZE=1 COLOR="#8e236b"><p align=CENTER>[This message was edited by Ken Fox on 05 December 2002 at 08:23 PM.]</p></FONT>

Jason, I have been using the Tube Works Blue Tube II for several years and I alway come out of it from the -20 dBm instrument out jacks and never had a hum problem using
Peavey DPC 1000 or Stewart power amps. I don't have enough tech knowledge to know which is correct but that is what always worked for me.
Jerry<FONT SIZE=1 COLOR="#8e236b"><p align=CENTER>[This message was edited by Jerry Roller on 05 December 2002 at 09:33 PM.]</p></FONT>

Ken, the output is unbalanced. I worked on one of these for a friend a few months ago. It was distorting real bad, a change of tube didn't help, e-mails to TubeWorks didn't help(in fact, they're about the most UNCOOPERATIVE people I've ever dealt with)-but a couple of turns on the little trimpot gain pot did the trick. It's right next to the tube, which I don't think even DOES anything.
And, BTW, Fox is a good dude to deal with! He knows his stuff, and doesn't mind sharing. I was gonna put this in a separate post, but this is a perfect opportunity. Thanks, Ken,I can't wait to get the Deluxe Reverb up and running!

If is unbalanced, then ground loop hum will occur for sure! That may not be the only problem that is there, but one to eliminate easily with a two to three wire adaptor on the AC cord! If the hum is still there after a ground lift, then time to get it returned/repaired under warranty.
Thanks for the kind words, Steve. How is that Deluxe Revefb coming along?
<FONT SIZE=1 COLOR="#8e236b"><p align=CENTER>[This message was edited by Ken Fox on 06 December 2002 at 07:50 PM.]</p></FONT>

Thanks for all of your help guys. Looks like everyone is using the -20dbm. Here are some more interesting facts. I was testing this preamp on my session400TLD and Nashville 400 because I have been waiting on my boogie power amp to come in.
Now, this is very, very interesting. My rig now consists of the Tubeworks pre-amp, a Peavey Tubefex and now this Boogie power amp. Well my tubefex and old profex2 always had a nasty hum with the peavey amps.
Check this out. Now with the boogie amp, I longer have that nasty profex or tubefex hum.
Now unless both of my Peavey amps were messed up, and I do not think they are. Just dumping my peavey amps have given me a wonderful clear sound. No hums or noise at all. Hmm??? Some how the peavey amps were creating noise that should not have been there? Thanks again guys. THis forum is wonderful.



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Jason (Slyde) Ory
Cullman, AL
Franklin D-10