Leslie 705 speaker rattle

[skippy]

G'day,

My Leslie 705 6"x9" Rotosonic speaker is getting tired and is starting to rattle and distort with any decent volume. The voice coil appears to move freely. It looks like the cone is getting soft and weak and is starting to distort when the volume is up. I have somewhat improved aging cones in the past by painting them with a solution of appr. 40% PVA wood glue and 60% water. But I really would like to replace the speaker with a fresh unit that can handle some punch. Any recommendations what to use and where to get it?

Thanks,
Skippy

[jimmywilliams]

First make sure the mercotac is good. If the speaker is the problem it is imeprative that you find an exact replacement - at least as far as weight is concerned. Otherwise the rotosonic drum will be off balance (I know from experience!). If you do need to use another 6x9 speaker of a differnt weight you will need to balance the roto drum accordingly. If you look in the drum you wil see that opposite the speaker there are pieces of metal bolted to the inside of the drum - that is the counterweight.

[kkeys]

Hi Skippy,

Re: mercotach
You could try this - worked for me for awhile. Pull the mercotach off the shaft end and shake it. I had distortion from one of mine on the slow speed.

[skippy]

Thanks Guys,

It is not the Mercotac. It is definitely a tired speaker cone. The distortion starts a higher volumes regardless of the rotor speed. These 6x9's just don’t cut it if you like to turn it up. I'm just looking for a 6x9 replacement that can handle the Leslie amp output at high volumes without complaining. I'm aware of drum balance implications. I planned to weigh the old and new speakers and place a lead weight on either the new speaker or the counter balance to make up the difference. Additionally I would suspend the drum vertically on it's axle to check for necessary fine tuning.

I have a set of 6x9 speakers out of a symmetric Conn pipe set. I wonder if they are suitable. Food for thought.

Skippy

[jimmywilliams]

The Conn pipe speakers are probably just as "robust" as the Leslie speakers! Maybe less so. I think the 6x9s in the later Rotosonic leslies were able to handle more power than the ones in the old Rotosonics I am more familiar with (like the 101, 102, etc.). Also I think the 6x9 in the 705 was 8 ohms, as opposed to 16 ohms in the older Rotosonics. I think you can still get car speakers in 6x9 size that are supposeddly designed to handle a lot of power but I can't vouch for frequency response. Also a lot of those are 4 ohms so maybe not a good idea. Wish I had something more solid for you...

[Hamman]

If you do opt for the "car" audio 6x9 either get a 2 way and disable the xover on the speaker itself and run full audio signal in just the 6x9 speaker portion (its woofer) eliminating the tweeter. Or better yet get a 3 way and just eliminate the tweeter on it so you would be just using the low and mid speakers of that 6x9. You would then have to redirect the tweeter highs back into the midrange though. The issue with car audio is their high freq. efficiency. Either one of those speakers I mention above would be to shrilly for that Leslie and would have to be dulled out a little. Or maybe you might like it.

[jdoc]

or put a spinet drum in like my 710 if it will fit, you will love it (unless you blow it up like I did LOL)

[skippy]

or put a spinet drum in like my 710 if it will fit, you will love it (unless you blow it up like I did LOL)

How did you blow your L710 baffle conversion? The L705 does not have a horn - just a Rotosonic and the usual stationary setup. But I use it with my Plumbers Horn which does the job admirably. And I'd like to keep it this way. Replacing the Rotosonic in a L710 with a baffle Leslie basically makes it a L720. Or almost a Solid State L122/147 etc.
But since I use both of my Leslies (L720 + L705) simultaneously with my C3 I just like the variety of sound I can produce by switching between them and the mixing of stationary and rotary channels (see attachment).
I think I'll start with re-enforcing the current Rotosonic 6x9 with my usual PVA glue solution. If this does not improve things I may try the car speaker solution.

Skippy

[jdoc]

I cooked the crossover and or the V21. I don't have access to it right now (long story) but the thing rocked when working. Balancing the rotosonic would be the issue, heavier magnet would require more counterweight and slower ramp up and long ramp down.
My Rotosonic was torn and worn anyways.