Leslie 122 questions...

[wurly76]

Hi there,

I'm new to the forum and after reading Jim's topic on tube choice for a Leslie, I thought I would ask a few questions about my recently acuired Leslie 122.

My setup at the moment is a Clavia Nord Electro (Hammond 'clone') plugged into a Leslie 122 which has been modified to accept a 1/4 inch jack input (see photos).

It sounds good, but I'm not sure that it's giving out it's full 40W when you turn it right up. I tried using a compressor unit that I had in the studio (Joe Meek VC3) as a pre-amp and this seems to help things, but I was wondering if anyone had any further thoughts or ideas?

the amp has been re-valved, and I checked out the speakers today... the top one is a Jensen and the 15 is EMI C15L? so i guess these may not be the original ones? They are a bit distorted around a couple of frequency's (mid-range ish) but not being an expert I wouldn't know if that was down to the amp or the condition of the speakers...

Also the amp only has one 12AU7 tube and in place of the other one, there is a connection to the Leslie Dividing Network... I guess this is a crossover? Can anyone explain why it only has the one 12AU7 valve? I thought the 122's had two?

Also what is that bolt on metal box on the left hand side of the amp!!!

thanks.

[Soul Stream]

I have no anwsers, except to say that's pretty freaky....one 12AU7 tube and that box on the side....never seen anything like it before. That said, these 122s get some pretty wild modifications over the years. My guess is that it has something to do with the footswitch being jammed in there. My advice would be to take just the amp (don't lug the whole thing down) to the local hammond repairman and ask him what's up....

Edited May 4, 2006 by Soul Stream

[Jim Alfredson]

Only one 12AU7 is used for the preamp (the one to the far right, if you're looking at the front of the amp). The other (on the far left) is used for switching the motor speeds. So the one that is still there is the correct one for the preamp. They might have put in some sort of solid state relay to switch the motors or they are just switching AC on and off (which works, but isn't exactly the best way to do it).

Those power tubes look like KT88s (EDIT: No, they look like 6550s. Nevermind!). I've heard some people like them, but I've never cared for them. I would try replacing them with a pair of good 6550 power tubes. I like the Electro-Harmonix.

One thing I've noticed with clonewheels is they rarely have enough output to adequately drive a Leslie amp. The signal of a Hammond is at a different impendence than a standard synth output. This usually means the synth (or clonewheel) won't have quite enough juice at the output to fully drive the Leslie and the volume will suffer. You might want to look into getting one of those preamps from Speakeasy Vintage. I've heard great things about them, but they are kind of expensive.

As far as distortion, it looks like you have the original V21 Jensen horn driver in there. These blow very easily. If you're hearing mid-range distortion, there's a good chance the horn is blown. The best replacement I've found is the one BT Productions sells. It's alnico, like the original Jensens, but it can handle 100watts instead of 40watts. I have one in my 21H and one in my 122 and I love them. They sound great. You'll have to get an adapter plate, which BT also sells, to mount the driver in the cabinet.

You could try putting a 12AT7 as the preamp tube as well. They have more gain than a 12AU7 but not quite as much as a 12AX7 (which usually just distorts like crazy... which can be cool in certain situations).

Hope this helps.

Edited May 4, 2006 by Jim Alfredson

[Soul Stream]

Hey Jim, what do you think that box is on the side?

[Jim Alfredson]

I'm not sure. It could be something to replace the motor switching. The only way to find out is to look underneath and trace the wiring and see what it's connected to. If it's connected to the outlets, then it's for the motors.

Also, I was right... there are KT88s... in the bottom picture!!! The top picture has 6550s. I knew I wasn't going crazy!

[Soul Stream]

I've never seen KT88s. What's the story on them?

[Jim Alfredson]

IIRC, KT88 are basically European tubes, in the same family as (and thus interchangeable with) 6550s but I think they bias differently than 6550s. Some people like them in Leslie amps, some don't. I personally feel that 6550s sound and perform better in a 122.

[wurly76]

Thanks for your help Jim.

The info about the tubes is interesting, I might try a pair of those 6550s and the 12AT7 for the pre...

Yeah, the output on the clavia is certainly not adequate to drive the Leslie amp, but since I wrote last, I have used a couple of different preamps in front of the Leslie amp and that seemed to give it much more punch. I tried a Peavey T-Raxx bass preamp which I found in the garage the other day... but I think it needs a service as it was making some weird rumbling noises every so often... then I tried a little Joe Meek VC3 (which is a vocal mic preamp?) which gave me much more gain, and some compression before going into the cab. Those speakeasy pedals are a bit expensive, and it's tricky trying to find someone who has one I can borrow in the UK... but I will perservere finding one to try.

I will look into the replacement horn though, as the cab does have a sort of 'buzzy' distorted sound around the midrange section. I tried listening to the top horn independantly to the bottom one by disconnecting the speaker wire, and it does sound like it may be blown.

anyway, I have a few more photos for you which may shed some light on the wiring route and the mystery box!

[wurly76]

Also, I was right... there are KT88s... in the bottom picture!!! The top picture has 6550s. I knew I wasn't going crazy!

[Jim Alfredson]

It appears that the mystery box contains two relays, for switching the motor speeds. That's a good way to do it, rather than just running straight AC and switching that (I've seend it done that way!) I would guess that whoever had this Leslie before you used it for guitar.

Some sort of preamp before the input to boost the gain is probably your best bet. Maybe something with a bit of EQ. I don't think you would need compression, but that's up to you.

Good luck!