Crossover Help for Elkatone Horn Driver

[bcmatt]

So, I've had this Elkatone rotary speaker cabinet for a few years and would like it to be a little more optimal for guitar for as little cost as possible. Someone closing down a local studio gave it away. The amp/crossovers/leslie control was missing, but the drivers, horn and DC motor remained.

20231027_091932.jpg

I previously made a pedal that uses a pcb boards that vary the voltage to have 2 separate (dialed in with knobs on the pedal) speeds when fed from a 12VDC adapter. I previously slapped a couple .68uF parallel caps on the horn driver to try and protect it using a 1st order crossover. It doesn't sound great. It could be blown.. or it could just be needing a better designed crossover.
The bottom cab has 2x 8 ohm 12" ceramic Jensens pointed straight down to the floor with no rotation effect in this particular cab.. I currently wired them in series to 16 ohm but I see according to a random Elkatone schematic that perhaps it is meant to be 4 ohms for their crossover.

elkatone speakers.jpg

Using a crossover calculator, I'm guessing they were going for 2nd order at 600Hz:

Crossover guess.jpg

I could try to replicate that, but I'm really tempted to limit the highs as well and treat the horn driver as a mid driver in a 3-way (without actually adding the tweeter obviously). That way I could potentially swap in a cheap/similar spec mid-horn driver like this:

Miyako.jpg

Seriously, this is literally the only only mid-horn driver I can find anywhere for less than about $400, and it seems pretty ideal spec-wise.
I've heard that proper Leslie horn drivers were really limited in their top-end response and were mostly staying below 6kHz, so I was wondering if I could use that cheap Miyako driver that seems to be the right throat diameter and impedance:

Horn driver throat.jpg

So, then, would I do something like these specs to make this mid driver crossover?:

3-way crossover for mid.jpg

So, I would just need 8uF and .68uF caps as well as 6.6mH and .65mH inductors to build just the mid part of the crossover using caps 2 and 3 and inductors 2 and 3.
I have no experience with working with crossover designs, so any advice would be helpful.
Also, any idea what impedance the amp will see? I'm trying to make it an 8ohm amp load.

[bcmatt]

Did I post this in the wrong folder, or just the wrong forum altogether?
Here is a view of the inside of the bass cab:

20231030_170047.jpg

[Stevem]

I think your post is suffering from lack of interest since it’s kinda way off the normal beaten path for a guitar amp related site.

You would likely get a far better response by posing this question on a home audio related/ speaker building site.

[bcmatt]

I think your post is suffering from lack of interest since it’s kinda way off the normal beaten path for a guitar amp related site.

You would likely get a far better response by posing this question on a home audio related/ speaker building site.

OK, thanks. I thought maybe of those sorts of sites, but I felt like they would not get my desire to make it sound ok on guitar and safe to use with my d-style amps. But, you are right that this is outside our usual areas of interest. It was a pretty low priority project even for me, and I'm the one who has had this cab for the last 6 years or so.

[Phil_S]

FWIW, that itty bitty midrange is going to carry most of the guitar frequencies. I don't know much about this stuff, but it seems reasonable to conclude that is why guitarists don't use hifi speakers.
Some reading that might help to frame this: https://producerhive.com/music-producti ... eat-sheet/

[sluckey]

Old organ forums might have more info.

[bcmatt]

Well, my bag of different values of inductors came. I quickly built the stock crossover 12uF and 4.7mH (I used 4.5mH). It leaves the bottom cab full range and at 4 ohms, and the horn driver is paralleled with it's crossover to keep it above 600 ish Hz. The cap is what you would use for about 580Hz and the inductor is what you would use for about 800Hz, so somewhere in there.
Playing it sounds actually pretty decent. I don't think the driver is blown. I think it's just that I was using a simple first order crossover as a placeholder that was pretty aggressive.... so when we were hearing only really high frequencies, they were just the worst part of a distorted signal. I think with it's actual stock crossover, the horn driver still doesn't sound amazing with more distorted signals, but that seems to be the same character I hear with any guitar through leslie sound on youtube. It's similar to when you hear a b3 with a bit of overdrive coming through. A little bit of that flavour can be fun at times, but you mostly expect to hear it clean.
I think this thing is good to use now. It's finally quite useable.

20231109_094556.jpg

PS Am I supposed to take the plastic wrap off the inductor? The metal leads already come out of it on the bottom and were useable without taking the plastic off.

[Stevem]

Good to hear you got it to your liking!

[martin manning]

Am I supposed to take the plastic wrap off the inductor? The metal leads already come out of it on the bottom and were useable without taking the plastic off.

I'd leave it on.

[bcmatt]

Good to hear you got it to your liking!

Ya, it was simpler than I expected. I was a little over-prepared to try a lot of complicated solutions. Since I had to pay $20 shipping anyways, I had bout about 5 different inductor values to try all sorts of stuff....
But the Stock values with the stock horn driver seems fine.

[bcmatt]

Am I supposed to take the plastic wrap off the inductor? The metal leads already come out of it on the bottom and were useable without taking the plastic off.

I'd leave it on.

Thanks!