Hello everyone, 🙂
I’m currently training as a cabinetmaker, and I’m working on a project to build a Leslie/Doppola speaker inspired by Dürer’s Solid (https://en.wikipedia.org/wiki/Polyhedron_of_Dürer). I also plan to design an electric guitar to match this amp. This post focuses primarily on the technical/electronic aspect of the amp (the guitar being a separate project). My goal is to create a Doppler-effect amp for electric guitar.
After some research, I’ve encountered a few dilemmas:
For now, I think a simplified version, like the Doppola or a design with a single speaker and rotating baffle, would be the most coherent, although the original Leslie cabinets are legendary… 😍
Thank you in advance for your advice and suggestions. I’m open to any resources or feedback on similar projects!
P.S. I’m French, so I apologize in advance if I make any mistakes in English!
I’m currently training as a cabinetmaker, and I’m working on a project to build a Leslie/Doppola speaker inspired by Dürer’s Solid (https://en.wikipedia.org/wiki/Polyhedron_of_Dürer). I also plan to design an electric guitar to match this amp. This post focuses primarily on the technical/electronic aspect of the amp (the guitar being a separate project). My goal is to create a Doppler-effect amp for electric guitar.
After some research, I’ve encountered a few dilemmas:
- Should I go for 1 or 2 speakers in my amp? Would this improve the sound quality?
- Should I faithfully replicate a Leslie cabinet, or consider a simplified design that might be less expensive and easier to build?
- What would be the best setup for guitar? Should I be inspired by David Gilmour’s Doppola, or go with a single-speaker configuration and rotating baffle? It seems to me that the Doppola has a less pronounced effect compared to the Leslie cabinet.
- Where can I find all the parts needed for this project? (My idea is to start with a tube DIY amp kit that I can assemble myself.)
- Where can I find schematics or plans for similar projects? Or even other specialized forums for this kind of project, perhaps?
For now, I think a simplified version, like the Doppola or a design with a single speaker and rotating baffle, would be the most coherent, although the original Leslie cabinets are legendary… 😍
Thank you in advance for your advice and suggestions. I’m open to any resources or feedback on similar projects!
P.S. I’m French, so I apologize in advance if I make any mistakes in English!
If you want to rotate the driver itself, the electrical contacts are a challenge. It's not rocket science but you have to avoid drop outs of the contact and you have to deal with the wear. To avoid that and to test if it's what you are expecting, you could use a trick: Don't rotate the driver, but instead mount it on the top of the box and use a sewage tube with a 87,5° bend (there are no 90° because they always need to have a downwards slope) on the front of the driver and just rotate it instead. That's a lot easier and can be mechanically much smaller. That way you won't have any wear on the contacts.
Instead of a typical guitar speaker you can also use a big full range driver or mount a horn driver co-axial on top of the guitar- or smaller FR-driver with high spl. The Ciare CH250 comes to my mind or the Eminence LEGEND B102 (both 10") or as 12" the B&C 320K/C-8A or the Beyma 12GA50. The Fane Sovereign 12-250 TC is also a excellent choice and not very expensive but is probably too flat in the response, but if you don't like it, you could use it as a HiFi speaker.
Thanks for your reply!
So, according to you, should I abandon the idea of using David Gilmour’s Doppola technique because it's too difficult to maintain? The rotating box would indeed be an interesting and simpler option to implement, but do you think the sound quality would be lower? Should I go for a configuration with 2 speakers (one for bass and one for treble like in the Leslie), or is that unnecessary for a guitar amp?
The 2-speaker setup is more technical due to the frequency crossover and the differences in rotation speed between the bass speaker and the tweeter. Also, fitting two speakers into an amp shaped like Dürer’s solid is a challenge! But if the sound quality improvement and the stereo effect are really worth it, maybe I’m willing to go in that direction.
Also I have already explored the option of using a full-range/coaxial speaker. If I understand correctly, this would allow me to have a more defined and wider sound with just one speaker, right?
From my research, the issue with this option seems to be that the low frequencies and high frequencies would be projected in the same rotating box with a single rotation speed. Since the Doppler effect doesn't affect low and high frequencies in the same way, wouldn't this create a clarity issue in the sound? This is why Leslie cabinets have two separate rotating elements with two distinct speeds.
Maybe the option of using a single rotating box with a full-range/coaxial speaker would be more than enough in terms of quality. Opting for a Leslie-style configuration might not be necessary and could be overly complex.
So, according to you, should I abandon the idea of using David Gilmour’s Doppola technique because it's too difficult to maintain? The rotating box would indeed be an interesting and simpler option to implement, but do you think the sound quality would be lower? Should I go for a configuration with 2 speakers (one for bass and one for treble like in the Leslie), or is that unnecessary for a guitar amp?
The 2-speaker setup is more technical due to the frequency crossover and the differences in rotation speed between the bass speaker and the tweeter. Also, fitting two speakers into an amp shaped like Dürer’s solid is a challenge! But if the sound quality improvement and the stereo effect are really worth it, maybe I’m willing to go in that direction.
Also I have already explored the option of using a full-range/coaxial speaker. If I understand correctly, this would allow me to have a more defined and wider sound with just one speaker, right?
From my research, the issue with this option seems to be that the low frequencies and high frequencies would be projected in the same rotating box with a single rotation speed. Since the Doppler effect doesn't affect low and high frequencies in the same way, wouldn't this create a clarity issue in the sound? This is why Leslie cabinets have two separate rotating elements with two distinct speeds.
Maybe the option of using a single rotating box with a full-range/coaxial speaker would be more than enough in terms of quality. Opting for a Leslie-style configuration might not be necessary and could be overly complex.
I think it's an issue to have it reliable. If you build it yourself and the construction is new, it probably fails when you actually need it working. If the speaker isn't rotating but the tube, the speaker can't fail because of the contacts, it can only fail to rotate the tube. It's not nice if the effect isn't working anymore but you can continue the gig or the practice session etc.
For a 2-speaker setup you don't need to build a 'HiFi-perfect' crossover. A capacitor in front of the smaller driver (or horn) is enough and you can easily change the loudness of the 2nd driver.
I thought with a full range speaker you only need one driver and be done since the effect is stronger the higher up you go frequency wise. And it's easy to build and cheaper too than two drivers. That way you can try if it behaves and sound like you wanted. And yes, a FR would give you more details and probably a better effect.
If you want to have the two speakers to 'rotate' (well, the tube bend instead), you could build the same thing for the tweeter as for the guitar/fullrange speaker. That allows you to control the speed of both independently.
For a 2-speaker setup you don't need to build a 'HiFi-perfect' crossover. A capacitor in front of the smaller driver (or horn) is enough and you can easily change the loudness of the 2nd driver.
I thought with a full range speaker you only need one driver and be done since the effect is stronger the higher up you go frequency wise. And it's easy to build and cheaper too than two drivers. That way you can try if it behaves and sound like you wanted. And yes, a FR would give you more details and probably a better effect.
If you want to have the two speakers to 'rotate' (well, the tube bend instead), you could build the same thing for the tweeter as for the guitar/fullrange speaker. That allows you to control the speed of both independently.
Alright, so the option of using a rotating tube with a fixed speaker seems to be the simplest and most reliable solution.
Having a fixed full-range speaker with a single rotating tube should give a satisfying result. I was just wondering if there could be interference between the low and high frequencies, considering that the Doppler effect, with a fixed rotation speed, would influence and affect frequencies differently between the lows and highs.
Should I try to find specific rotation speeds where both low and high frequencies are harmonious? Or maybe these "interferences" are minimal and could actually contribute to the aesthetic of the amplifier.
In the other case, if I wanted a "perfect" amp without Doppler effect interference between low and high frequencies, I would need to build a Leslie-style "horn" tweeter, which seems much more complex. Additionally, horn speaker parts are expensive, and I’m not sure if there’s a simpler design or alternative for a rotating high-frequency speaker. This path is probably too complicated to pursue...
Having a fixed full-range speaker with a single rotating tube should give a satisfying result. I was just wondering if there could be interference between the low and high frequencies, considering that the Doppler effect, with a fixed rotation speed, would influence and affect frequencies differently between the lows and highs.
Should I try to find specific rotation speeds where both low and high frequencies are harmonious? Or maybe these "interferences" are minimal and could actually contribute to the aesthetic of the amplifier.
In the other case, if I wanted a "perfect" amp without Doppler effect interference between low and high frequencies, I would need to build a Leslie-style "horn" tweeter, which seems much more complex. Additionally, horn speaker parts are expensive, and I’m not sure if there’s a simpler design or alternative for a rotating high-frequency speaker. This path is probably too complicated to pursue...
I think it would be best to just make the speed adjustable with a two pots and then put a switch in to alter between both adjusted speeds. That means you can adjust it at any time or just switch between them. Just find a motor control kit or circuit. To use the speaker without the effect, just switch the motor off.
The horn and driver will not be expensive, you can get both for 30-40€. From Thomann or TLHP, also TLHP etc. There are cheap horns too, I'd get them from eBay and then modify them to a bent or combine two to get a better balance.
The horn and driver will not be expensive, you can get both for 30-40€. From Thomann or TLHP, also TLHP etc. There are cheap horns too, I'd get them from eBay and then modify them to a bent or combine two to get a better balance.
Alright, so the parts aren’t as expensive as I thought—I must have come across vintage parts... So, I should buy a driver speaker and then build/buy the rotating horn that is mounted with a ball bearing onto the driver speaker, if I understood correctly?
I found this item online: https://www.bborgan.com/products/leslie-plastic-horn-with-large-pulley?_pos=3&_sid=f4547d6a3&_ss=r (Is this what you call the "horn"?)
Do you know if there are complete DIY kits for this style of horn speaker with the rotating horn attached?
This is really interesting to study this!
After discussing this topic on a French forum, someone advised me to go with a version using just one speaker, as it would likely be simpler for a beginner, and I would never be able to match the quality of a real Leslie. I tend to think too "big" with some projects. Maybe a single-speaker configuration would still be easier and less frustrating for my project (allowing me to fully focus on the guitar design and Dürer solid). A two-speaker setup would probably be a time and energy drain for a sound quality that might not be significantly better than with just one speaker.
I found this item online: https://www.bborgan.com/products/leslie-plastic-horn-with-large-pulley?_pos=3&_sid=f4547d6a3&_ss=r (Is this what you call the "horn"?)
Do you know if there are complete DIY kits for this style of horn speaker with the rotating horn attached?
This is really interesting to study this!
After discussing this topic on a French forum, someone advised me to go with a version using just one speaker, as it would likely be simpler for a beginner, and I would never be able to match the quality of a real Leslie. I tend to think too "big" with some projects. Maybe a single-speaker configuration would still be easier and less frustrating for my project (allowing me to fully focus on the guitar design and Dürer solid). A two-speaker setup would probably be a time and energy drain for a sound quality that might not be significantly better than with just one speaker.
After deciding to go with a simplified version of the Leslie, I now need to define the main components to use. To recap, I’m also planning to build a guitar that will sonically and aesthetically match the amp, and I’ve opted for a Les Paul-style model.
I know that choosing the components is often a matter of personal taste, but I’m a bit lost and not really sure where to start. My goal is to go for a tube amp kit, as I’d like to achieve that warm tone that pairs well with a Les Paul (although I imagine the sound will also depend on the pickups). I’m thinking that a 12-inch speaker would be a good fit for this project.
As for the pickups and the amp, I’m still undecided. Obviously, I’ll be going with humbuckers (splittable or not?). I don’t plan on using this guitar for heavy metal tones. Since I also like funk, I’ll probably leave that to my Strat, so splittable pickups may not be necessary. The two main styles I want to explore are rock and jazz.
Regarding the amp, I’ve heard about the 5E3 Tweed Deluxe kit, which could be a nice option, but I haven’t formed a strong opinion on it yet. I’d love to hear your personal experiences and opinions to help me refine my choices and make my own decision.
And of course, I’m also looking for a motor for the rotating system of my Leslie! I’ll keep you posted!
Thanks in advance for your advice!
I know that choosing the components is often a matter of personal taste, but I’m a bit lost and not really sure where to start. My goal is to go for a tube amp kit, as I’d like to achieve that warm tone that pairs well with a Les Paul (although I imagine the sound will also depend on the pickups). I’m thinking that a 12-inch speaker would be a good fit for this project.
As for the pickups and the amp, I’m still undecided. Obviously, I’ll be going with humbuckers (splittable or not?). I don’t plan on using this guitar for heavy metal tones. Since I also like funk, I’ll probably leave that to my Strat, so splittable pickups may not be necessary. The two main styles I want to explore are rock and jazz.
Regarding the amp, I’ve heard about the 5E3 Tweed Deluxe kit, which could be a nice option, but I haven’t formed a strong opinion on it yet. I’d love to hear your personal experiences and opinions to help me refine my choices and make my own decision.
And of course, I’m also looking for a motor for the rotating system of my Leslie! I’ll keep you posted!
Thanks in advance for your advice!
Following with interest! One of the Leslie cabinets I've messed with had a Mercotac, that supplied a 6x9 mounted in the bass rotor. I would go the Leslie upper rotor route though for the reasons already posted.
https://mercotac.com/
https://mercotac.com/
Mercotacs are really cool!! But I wonder if it might still be too complex to implement since this is my first guitar amp project, and the two-speaker setup might also be too complicated.
If I find a detailed internet post about building a DIY Leslie cabinet, maybe I could start this project with 2 speakers, but doing the research seems too complicated given my deadlines for this project.
If I find a detailed internet post about building a DIY Leslie cabinet, maybe I could start this project with 2 speakers, but doing the research seems too complicated given my deadlines for this project.
I figured out awhile back that the sound I was looking for was the upper rotor. The lower can be done decently with a simple automated eq of some kind, imho. The lows are not very directional, of course. I think there's a popular Leslie emulator that has a physical horn and electronically simulates the lower tremolo (forget the name atm). It might be useful to look for one of these used if within your budget - I know that's where I'm leaning for my own project. Will post back once I remember the details.
Edit: http://theatreorgans.com/hammond/faq/files/pro3review.html and https://www.msamps.com/pro-3xhttps://www.msamps.com/pro-3x but they are way pricey new. The horn, bearing assembly and driver (doesn't have to be the original - newer designs are way cheaper, more robust) should be in the $200 USD-ish range, depending upon buying used vs new. That leaves the motor, which is the part I haven't figured out yet myself.
The mercotac requires some kind of axle and wheel, and is definitely more complex/challenging vs a relatively simple bearing as used in the conventional Leslies 🙂
Edit: http://theatreorgans.com/hammond/faq/files/pro3review.html and https://www.msamps.com/pro-3xhttps://www.msamps.com/pro-3x but they are way pricey new. The horn, bearing assembly and driver (doesn't have to be the original - newer designs are way cheaper, more robust) should be in the $200 USD-ish range, depending upon buying used vs new. That leaves the motor, which is the part I haven't figured out yet myself.
The mercotac requires some kind of axle and wheel, and is definitely more complex/challenging vs a relatively simple bearing as used in the conventional Leslies 🙂
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It's a model I came across at the beginning of my research (Pro 3x), and it’s well-known. Indeed, with Leslie cabinets, the Doppler effect is mostly noticeable in the high frequencies, which is why the 'horn' is so important in Leslie speakers. Having this setup for my project would improve the quality. If I understood correctly, you’re considering buying a Pro-3x, which I would integrate into a new chassis for this project?
There’s also the Fender Vibratone, which is more like a 'guitar version' of the Leslie. I'm thinking of going with a 12-inch speaker and a Les Paul-style guitar because I’m aiming for a round, warm sound. With this configuration, maybe a horn isn’t really necessary?
Building a horn speaker in a rotating sphere with a Mercotac would be really cool, but unfortunately too complicated... 😕
There’s also the Fender Vibratone, which is more like a 'guitar version' of the Leslie. I'm thinking of going with a 12-inch speaker and a Les Paul-style guitar because I’m aiming for a round, warm sound. With this configuration, maybe a horn isn’t really necessary?
Building a horn speaker in a rotating sphere with a Mercotac would be really cool, but unfortunately too complicated... 😕
Yes, I was until I checked prices a short while ago; only if reasonably priced for a used unit to pull the components from. I have a need for a total of 3 horn assemblies, and I'm thinking it's cheaper and more flexible to do a DIY approach. I'll be doing a class D/dsp crossover and eq type of design, and one unit will be slaved (sorry for the word) from the output of a guitar amp (edit: this one may well be a simple crossover, pad and high cut all in the analog domain)
A Vibratone is cool too. It's a different type of vibe than a horn of course. You might be able to find a vintage/used unit that originally was in an organ. Don't know about availability in the EU/France, but there were a bunch of organs of the 60s/70s era that used them. Typically, they were a styrofoam rotating assembly that a 10"/12" sized speaker fired into (which you already likely have seen and know about 🙂 )
A Vibratone is cool too. It's a different type of vibe than a horn of course. You might be able to find a vintage/used unit that originally was in an organ. Don't know about availability in the EU/France, but there were a bunch of organs of the 60s/70s era that used them. Typically, they were a styrofoam rotating assembly that a 10"/12" sized speaker fired into (which you already likely have seen and know about 🙂 )
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Too late to edit my post (again...) but here's an example over on this side of the pond (Ebay search: rotary speaker):
https://www.ebay.com/itm/375689168343
There are lighter, smaller examples that use foam as the rotating baffle that appear as well. HTH
https://www.ebay.com/itm/375689168343
There are lighter, smaller examples that use foam as the rotating baffle that appear as well. HTH
I really love the idea of using a tube amp because of its organic, warm, and analog sound. This fits perfectly with the aesthetic I'm going for, inspired by sacred geometry and organic forms. The tube amp’s physicality and warmth align with the overall philosophy of my build, which is meant to reflect something natural and almost "alive." But maybe it’s to complicated for a beginner.
However, this is also a competition piece, which means the setup will have to withstand transportation and possibly rough handling. That’s where the tube amp becomes a bit of a concern due to its fragility.
I'm considering a hybrid approach, maybe using a tube preamp for the warmth and then relying on more robust components like a Class D or solid-state power amp for durability. For the Leslie speaker part, I'll continue to explore how I can make the horn speaker. If it turns out to be too complex, I'll go with a Vibratone setup instead. For the horn option integrating a crossover to manage frequencies between the low-end driver and the horn.
Still debating whether to go full analog or incorporate DSP-based EQ and crossover for more control and precision. Maybe analog is much easier to set up and will have a more traditional sound? But the precision of digital DSP could also be great for achieving the most accurate and wide-ranging sound possible?
Do you have any component ideas in mind and websites where I could find DIY kits that match this approach?
Thanks again for your advice!
However, this is also a competition piece, which means the setup will have to withstand transportation and possibly rough handling. That’s where the tube amp becomes a bit of a concern due to its fragility.
I'm considering a hybrid approach, maybe using a tube preamp for the warmth and then relying on more robust components like a Class D or solid-state power amp for durability. For the Leslie speaker part, I'll continue to explore how I can make the horn speaker. If it turns out to be too complex, I'll go with a Vibratone setup instead. For the horn option integrating a crossover to manage frequencies between the low-end driver and the horn.
Still debating whether to go full analog or incorporate DSP-based EQ and crossover for more control and precision. Maybe analog is much easier to set up and will have a more traditional sound? But the precision of digital DSP could also be great for achieving the most accurate and wide-ranging sound possible?
Do you have any component ideas in mind and websites where I could find DIY kits that match this approach?
Thanks again for your advice!
I haven't got far with the actual end-game DSP system, but I'll probably go with a SBC approach. Maybe there's some help to be found in the Digital Source section here on DIYAudio? Not much help from me yet, sorry 🙂
a dual brush ring assembly is rated a 5kw. i would take a 4 ring assembly, for safety, check them out at aliX
Well, that is surely a good solution but requires a high precision mechanics. And that makes it expensive if you don't have access to a metal fabrication shop. Yes, that's the best technical solution but not the best for @Backel if he's not sure what he really wants. Aside from that, it's not relevant if it's capable of 5kW but if/how much noise it's making. Mind you, not necessarily mechanically but electrically. Power wise it doesn't matter but signal wise induction and HF interference are actually quite a sensitive matter.
Interesting subject I hadn't thought about in ages. Back in the latest sixties when I was a young teen, my Dad came home from a business trip with special gift for his piano playing kids -- 3 of us, but mostly me: a massive Yamaha electronic organ with dual keyboards, 100+ keys & 1.5 octave bass pedals. It had a huge ear-shaped flat styrofoam main speakers maybe 3.5 by 2.5', and a flat rectangular smaller speaker of the same type in a separate chamber on the right side. The smaller speaker spun via motor on its short axis, and its speed was infinitely variable for Leslie speaker effects from slow phasey wah-wah to really fast woop-woop. It was a lot of fun to play around with. I think my enthusiastic garage band figured out how to run electric guitars through the amp & wah-wah speaker in the organ.
A web search suggests it might have been an Electone E-3.
Anyway, this spinning speaker would be hard to replicate without some extensive mechanical design & fabrication resources. Can't think of any light flat speakers that be adopted. But the basic Leslie speaker effects shouldn't be hard to emulate: it's just a deflector in front of the speaker that spins at different speeds causing variable phase effects and reflections, right? I picture a 4- blade box fan with 2 opposite blades removed, positioned in front of a normal 12/15" instrument/pro driver, spinning at different speeds. The motor would probably need to be replaced with something a lot quieter than what's in a regular house fan + speed control, perhaps with foot pedal or switch? A precision DC motor, probably...
A web search suggests it might have been an Electone E-3.
Anyway, this spinning speaker would be hard to replicate without some extensive mechanical design & fabrication resources. Can't think of any light flat speakers that be adopted. But the basic Leslie speaker effects shouldn't be hard to emulate: it's just a deflector in front of the speaker that spins at different speeds causing variable phase effects and reflections, right? I picture a 4- blade box fan with 2 opposite blades removed, positioned in front of a normal 12/15" instrument/pro driver, spinning at different speeds. The motor would probably need to be replaced with something a lot quieter than what's in a regular house fan + speed control, perhaps with foot pedal or switch? A precision DC motor, probably...