Trek II and Leslie 142 question

[Analogaddict]

I just scored a Trek II UC-1A preamp, which I'd like to use with a Leslie 142. One thing I can't figure out is if the Trek supplies power for the Leslie. The Leslie is modded with a power cord of its' own and an on/off switch, and I would like to try and avoid setting fire to something by feeding it too much power. Does anybody know if the Trek alone will power the Leslie? If I connect the Trek and the Leslie power cable, will I blow the Leslie up?!

[MoodyBluesKeys]

Trek II preamp output connections - type of Leslie

 

Looks like connection should be to the "Group 3" output for a model 142 Leslie.

Note that this is for a STOCK 142. Would be best to remove the modifications before hookup.

[hazerkeys]

Moody is right on ... I have a 145 and just plug it into the group 4 connection - provides the all power, switching, etc - all good !! (run my clones in via the 1/4" and sounds great)

[WesG]

I agree. Separate power cord for a Leslie which was not designed that way is never a good idea, IMNSHO. Although at least the 6H are probably the mostly likely to "get away with it" since the DC ground is only used for B+ supply on pre-B2 organs, speed switching on some organs, and ground loops will go unnoticed due to the balanced signal.

 

Plugging into to two power supplies at once can definitely spell trouble. At least you will be much more likely to trip a GFCI. If the Leslie and Trek II box are wired up in different phases (or one outlet is wired out of phase) you will blow the breaker.

 

Wes

[OB Dave]

When you say the Leslie has been modded, do you mean the amp itself has been modified? The business end of a stock 122/142 amp should look something like this:

 

http://www.captain-foldback.com/Leslie_sub/decor/242_amp.jpg

 

Where does the power connection go? If the power is being supplied via a separate box that ultimately plugs into that round six pin connector on the right, you should be able to unplug that box and plug the Trek II into the amp. Otherwise, here be dragons.

 

A photo of your setup would be helpful.

[Analogaddict]

Thanks for all the answers! I'll take a look and some pictures tomorrow. Hopefully, it's the way Dave writes with a separate box - I won't take any chances since I have zero electrical knowledge.

[Analogaddict]

Photobucket seems to be down, but it's all up and running now. A friend with slightly more electrical knowledge helped me out, and it turns out there was a 110 -> 220 transformer installed in the Leslie, and the power went from there straight to the amp. The trek only controls speed and acts as interface... I tried it with my SK-1 and it sounds fantastic.

[Dana.]

http://img1.wikia.nocookie.net/__cb20070916150913/uncyclopedia/images/b/b6/Kirk.gif

 

KHAAAAAN!!!

[Analogaddict]

Sounds friggin' awsum.

http://i28.photobucket.com/albums/c213/analogaddict/Mobile%20Uploads/5244428C-F760-487B-8803-5B959D0E860B.jpg

 

http://i28.photobucket.com/albums/c213/analogaddict/Mobile%20Uploads/ADDFD6E9-6D8B-4502-AF9C-1540F775E4A3.jpg

 

 

http://i28.photobucket.com/albums/c213/analogaddict/D0045532-3234-4838-9935-ACDD62E459F9.jpg

[OB Dave]

Oh.... it took me awhile to figure out what was going on, but I think I get it.

 

Looks like you have a 240v Leslie but a 120v Trek II pedal. So the Trek II pedal is plugged into a 240-120v step down transformer, and then the extra transformer inside the Leslie steps everything back up to 240 volts to accommodate the 240v 122 amplifier.

 

It also looks like you have original Leslie-branded Tung-Sol power tubes, which are probably 40+ years old. The other three tubes will last decades, but the 6550s do wear out over time.

[MoodyBluesKeys]

But until the original Tung-Sol 6550's DO wear out, they are better than any current replacement. Today's "Tung-Sol" tubes are NOT the same. If you don't push the 142 real hard, they may last for years.

Example: I have a ham radio amplifier that uses three 811A tubes. Brand new Chinese made tubes best output I can get is about 375 watts with 100 watt drive. With three old stock RCA tubes from the 1960's I get 500 of the original rated 600 watts. Of course each of the oldies cost me more to buy a couple of years ago than 6 of the new ones.

 

Also keep the small tubes running as long as you can. Modern replacements are not as good.

 

[OB Dave]

Agreed. It depends on the design of the amp. In my experience Leslie amps are pretty rough on the 6550s. I have several old Leslie-branded Tung-Sols here, and they just don't have any oomph left in them. Very little gain before breakup. I keep them because they're cool to have around, but they're unusable as power tubes. As brittle as the new Tung-Sols sound, when you need new tubes you need new tubes. The now-out-of-production-but-still-generally-available Czech Tung Sols sound better than the new Chinese ones.

 

About ten years ago I bought two pairs of NOS Mil-Spec GE 6550As, made in the mid-1980s. Those are absolutely magnificent tubes. I regret not having bought up their entire inventory of them.

[MoodyBluesKeys]

Way back 50 or so years ago, I helped put the New Bern, NC TV station on the air. Just about all the equipment was tube, we had a RCA card-matic tube tester that was kept running all day testing tubes. The RCA 2" quad video tape machines used three groups of four 6550's in amplifiers to drive servo motors.

Like the Leslie, they were hard on tubes - even the GE and TungSol tubes of the day typically started showing loss after a few months.

 

I wish I had all of the "pulls" that we made from those video recorders.

I have a brand-new pair of RCA mil-spec replacements for the 6BQ5's in my Fender guitar amp (it has NOS 6Bq5's and 12AX7's in it now). Definitely makes a difference.

 

Baldwin used four 6L6GB tubes in their amps, but only ran the amp at 40 watts. Not unusual to check a 20 or more year old amp and find the tubes still close to full rating. Leslie did push their amp harder.

 

I was in electronic service when the first wave of foreign made tubes came about. I do regret not picking up some US made and just keeping them around. When I first started getting Russian made tubes (Sovtek) in white boxes, I was careful not to tell customers just where the tubes were made - many of my customers would not have been pleased.

 

I still remember tubes fondly - products could actually be repaired with common tools.

 

[Analogaddict]

Tubes still appear from time to time. I have a couple of old tubes salvaged from an old radio and from my grandparents' basement. My grandfather never threw anything away, including the NOS Mullard AU7 running in my Leslie 3300 today.