122RV - which ports and louvres are "Stock 122"?

[Papus]

My 122RV was relieved of the RV components long ago in the distant past....
Which ports on the horn shelf are found on a "stock 122"?
On my 122RV, the left two circular ports are covered from below with some sort of layered paper or matting of some kind - is this stock?
The right two circular ports are wide open.
Similarly, the left RV louvres are blocked internally by a thin piece of wood, the right side is wide open.
There is audibly more dry woofer bleeding through on the right side of the cabinet, presumably via these circular ports and the RV louvres.
Lastly, what is the purpose of the diagonal cut-out on the woofer shelf?

[andyg]

The 122RV had one reverb speaker (though I have seen UK examples with two) so one set of louvres would be blocked off. If the reverb speaker has gone, then you should close off the louvres to prevent leakage from the woofer.

I've never seen those holes on the top shelf in any leslie, and they do look rather roughly cut. I'd block them off with wood to stop the obvious leakage that will occur.

Looks like a previous owner liked leakage! In the same way that some people disconnect the motors from the lower drum to get a straight low frequency sound. Each to their own, I think that's ghastly and can't listen to it for more than a few moments, however good the player!

Diagonal cut out - that's meant to be there on the 122/147 (my UK assembled 145 had one though it should not have!) and is, I believe, effectively a bass port. Someone here will know for sure.

[David Anderson]

I've seen the holes in the horn shelf. They are usually accompanied by boxes around the reverb speakers as in the 251. I agree: block them off.

[Goff]

The second set of holes on the left where the reverb amp would go looks unusual not unless your cab is not an RV but some other model like the 251 which has two 6x9's with accompanying black box enclosures.

My 122rv has just the one set (double holes) on the right and yes, the 6x9 reverb boxes enclose the holes on the right and yes a stock pad of wool filled paper is found to block off the holes even if there is a 6x9 speaker in use.

I took off the paper as it absorbs moisture and just put a wad of fiberfill and then a top layer of felt.

And yes I do have the original reverb system set up with just a single 6x9 with black box enclosure on the right and it all works. Not the best sounding but it's original.

I imagine the holes are there to mix some of the reverb sound from the 6x9's to enter the upper rotor cavity and get swished around by the movement of the rotor. With the black enclosures over the 6x9's at that spot, this is the only answer that makes sense as to why the holes as the woofer would be blocked off from the 6x9 enclosure so any leakage of the woofer would not be happening as much.

Your cab has the block-off panel on the left as does mine so strange if it was a 251 why is the block off panel on the left and not on the right?

Must be one of those 251 cabs sent out as an RV?

In your third photo I noticed the hole in the baffle where a cork would go to plug the hole for the wires going to and from from the stock reverb amp, just off from where the original reverb amp would sit.

There would also be a rectangle of aluminum foil stapled to the area above the reverb amp's location to act as a heat shield coming off the tubes on the amp from heating up the top of the Leslie.

But an RV's upper rotor cavity is taller than a 122 and not sure what a 251's upper rotor cavity height would be, but the RV I have is 6 1/4" from baffle to inner ceiling.

The RV's taller space height is what Gregg Allman liked about his RV cabs for the way the sound would come out of the taller cavity.

[Papus]

Wow, that's an overflowing font of valuable information! thanks.
My horn cavity is definitely taller than usual - the horn rotor simply lifts straight out, no need to drop the horn driver assembly from below. This is very handy for swapping between horns with/without deflectors.
Sounds like I need to block EVERY hole in the horn shelf and also the RV louvres on both sides - I'm not a fan of the dry woofer leakage.
But I am very glad to have the taller horn cavity - makes life easy with internal mic mounts and changing the horn rotor!

[Goff]

Yes, the horn just lifts up and clears the driver tube. When moving the Leslie for concerts I stretch a rubber band over the horn snagged to two small screws so in case a roadie decides to lay the Leslie on its side (it's inside a well made flight case) the horn won't slide off and crack.


Yes you can block off all the holes since you don't need them. Maybe put some gasket material, felt, thin rubber, so it doesn't vibrate up against the panels and is air-tight.

If you need to use the hole for wires get a cork from a hardware store and you can wedge that into the hole retaining the wires as that's how they did it at the factory.

[Papus]

Thanks Goff, great advice!
My Leslie is enjoying an easy life in my studio, it's not going anywhere anytime soon.
I will definitely sandwich a thin layer of dampening material between the cabinet and the wood covers for the holes....
I play my 122 very LOUD, it has thrown off quite a few sets of house keys and empty cans of beer from the top of the cabinet on a number of occasions with heavy bass riffing.
I doubt an actual V21 would have lasted long under my levels of abuse!

[Hamman]

"But an RV's upper rotor cavity is taller than a 122 and not sure what a 251's upper rotor cavity height would be, but the RV I have is 6 1/4" from baffle to inner ceiling."


Hmmmm...Never thought about this...nor have I ever owned an "RV" type Leslie. My 251's are exact in dimensions as my 122's as it pertains to the upper shelf clearence.
However, on a "RV" cabinet....did they just move the top shelf down to fit the reverb amp? Or, is the total height of the Leslie cabinet higher by the amount needed in the space for the reverb amp?

[David Anderson]

The 251 cabinet, including the horn compartment dimensions, is the same as a 122. The RV cabinets had a taller horn compartment (at the price of reducing the volume of the woofer enclosure) to accommodate the reverb amp. Since the secondary output channel of a 251 is on the main amplifier chassis, there was no need to change the horn compartment dimensions.

The earliest Leslie reverb cabinets were the 22R and 47R that appeared in 1960. They featured the taller horn compartment and all hole pre-drilled (plus side louvers) for the Hammond ETK reverb system that was available to retrofit reverb into Hammond Organs like the M-series spinets. In other words, they did not ship from Leslie with reverb; it was installed by the organ dealer or owner. According to Sal Azzarelli, relatively few ever actually had the reverb system installed.

In 1965 Leslie came out with their own similar reverb system with both V and RV cabinets. A 122V came from the factory ready for reverb, but without the reverb components installed. A 122RV (or 147RV) came with the full reverb system installed. Reverb cabinets also had steel shields on the lower slow motor to reduce hum pickup by the reverb tank.

I have worked on a 247RV with the whole system still intact.

[Papus]

Hmmmmm...... this makes me think my 122 started life as a 122V, as there is no sign of the reverb amp or speakers ever having been present - either that or the removal job was exceptionally tidy!

[Hamman]

The RV cabinets had a taller horn compartment (at the price of reducing the volume of the woofer enclosure) to accommodate the reverb amp.

Yep that's what I figured...thanks David!

[Goff]

I bought a complete vintage Leslie reverb system from Classic Hammonds as the RV's was missing when I bought it.

Fortunately Steven had all the accessories that came with the original RV system.

I wanted to restore the RV to a factory type set up. It had to be repaired though to get it to work but was in good condition overall.

The tubes are vintage originals. The kind with the radioactive elements.:o

And if you've never seen an RV's reverb amp in operation, there is a light show when the speaker is played as there is a light bulb used as a limiter device inside the amp so as you play organ through the speaker, the amp pulses with each key stroke producing a bright white light that increases in intensity depending on the volume sent to the speaker.



I wanted the circuit constant tone by having the reverb amp in the circuit.

And the tank had to be mounted under the 6x9 as being mounted on the factory position of the woofer back panel, introduced hum.

Both 122/147 and the RV Leslies are the same size overall.

Yes they did make the woofer cab smaller to get height for the reverb amp. The amp creates heat and would not survive inside the woofer cab nor is there space down by the lower rotor that would make any sense for repair issues to anything in the rotor cavity.



The back woofer panel is shorter than the 122's and at (21 7/16ths from top to bottom of the panel) will not fit anything but an RV cab.

There isn't a noticeable difference in low frequencies with the RV's smaller woofer cavity.
There is however an increase in the sound dispersion of the treble rotor. Which is what some who prefer this cab look for in this Leslie.

[Papus]

The horn compartment rear cover appears to be taken from a standard 122...... my RV's horn cover is the full height of the cavity..... but it's been removed since 1996 and never been put back on hahahahahaha

[David Anderson]

The Leslie RV reverb amp I worked on needed all new electrolytics in the front end as some had gone completely open-circuit, but when repaired, it put out 19 Watts clean, which is impressive for a 2 x 7189 amp.

[Goff]

The Leslie RV reverb amp I worked on needed all new electrolytics in the front end as some had gone completely open-circuit, but when repaired, it put out 19 Watts clean, which is impressive for a 2 x 7189 amp.

And those 7189 tubes are the ones with the radioactive material.

Should they break, hazmat suit time. :o

I bought an extra lamp bulb for the limiter but need to get stock of the 7189.

So far the amp has hung in there through numerous pro concerts.

If it happens to conk out, just have to bypass the 122's output direct to the xover which now goes to the reverb amp first in the chain

[David Anderson]

A 7189 is just a premium/uprated EL84 designed for higher plate voltages.

[Papus]

Suspicion confirmed!
Mine is a 122-V, never had the reverb amp or speakers fitted.

[Goff]

David Anderson commented
Yesterday, 09:31 PM
A 7189 is just a premium/uprated EL84 designed for higher plate voltages.

Yes I remember that now. The EL84's will not handle the circuit well and is needed to be pointed out for this amp.

And the price of the 7189 has gone up in the last several years.

[Goff]

Papus commented
Yesterday, 07:21 PM
The horn compartment rear cover appears to be taken from a standard 122...... my RV's horn cover is the full height of the cavity..... but it's been removed since 1996 and never been put back on hahahahahaha

Yes, my RV didn't come with covers so eBay to the rescue. Anything to keep the rotors protected. Was able to find a set (top/bottom).

The upper panel I received has the horse hair acoustic insulation on the inside.

The cover for the reverb tank access hole is a freebie key fob promo from Zildjian made from real cymbals, with a piece of rubber to act as a vibration gasket.


The original RV panels do cover more of the upper cavity.

Comparing the two covers you can see how much larger the RV's cavity is compared to the 122.

[Papus]

Found mine

[Goff]

Cool, hang onto that. You can't find them.

[Papus]

I'm happy to take precise measurements if anyone wants to fabricate their own.
It's pretty basic: rectangular straight edged piece of 12mm pine ply with two pilot holes and a semicircular cutout for the microphone.