Here's a rare opportunity to acquire a set of Oleg Rullit Aero field coil 10" drivers and potentially (if you pick up) some cool bruce edgar back horn enclosures.
These drivers are an entirely different animal than Rullit drivers with vintage paper cones. If you look on that famous auction site, you will see that Oleg lists permanent magnet versions of these Aero drivers at over $4000.
The field coils are powered by 150V and I will include a regulated, linear Lambda power supply.
Also included are a pair of absolutely incredible solid walnut "waveguides" for the Rullits. These really worked a charm with my back loaded horns, giving a boost to the low mids in a way that mated with the natural roll off of the back horns. These were built by a Swiss furniture maker and are things of beauty. You can seem them in the picture of the Rullit in the back horn by the piano.
I'm asking $1750 for the drivers, power supply and solid walnut waveguides.
I'll ship the drivers + power supply + "waveguides" anywhere in the world, but the cabinets are free for pick up with the drivers.
The condition on the drivers and front horns is very good/excellent. The power supply works fine but is an old surplus item (it is, however, worlds better than the cheap switching supplies often used to power field coils these days)
For local pick up with the drivers, I'm also offering a choice of enclosures free. These are not graded for condition, but I would say they are "fair". Note that the purchase price is for the drivers and front horns for them; you get the enclosures if you can pick 'em up and get them out of my garage.
The first is a set of Bruce Edgar designed back horns built out of a very curved laminate of wood and fiberglass. They are very heavy and you will need to pick them up. The JMLC horns in the picture are neither included nor available. The pain on them is automotive high gloss, but it was applied by yours me, so it is only so so. Another sanding and coat...
I've also used these horns with Lowthers and Voxativs + adapters. They work great, and they are configured so you can take the top off and access the throat and back chamber to make adjustments.
The second is a simple 50L plywood box, which is nicely finished on the sides in walnut veneer. You can't see the sides in the picture.
These later boxes aren't really worth anything, but you can have them.
The Edgar back horns are very special, but you have to pick them up.
Please reach out with any questions.
These drivers are an entirely different animal than Rullit drivers with vintage paper cones. If you look on that famous auction site, you will see that Oleg lists permanent magnet versions of these Aero drivers at over $4000.
The field coils are powered by 150V and I will include a regulated, linear Lambda power supply.
Also included are a pair of absolutely incredible solid walnut "waveguides" for the Rullits. These really worked a charm with my back loaded horns, giving a boost to the low mids in a way that mated with the natural roll off of the back horns. These were built by a Swiss furniture maker and are things of beauty. You can seem them in the picture of the Rullit in the back horn by the piano.
I'm asking $1750 for the drivers, power supply and solid walnut waveguides.
I'll ship the drivers + power supply + "waveguides" anywhere in the world, but the cabinets are free for pick up with the drivers.
The condition on the drivers and front horns is very good/excellent. The power supply works fine but is an old surplus item (it is, however, worlds better than the cheap switching supplies often used to power field coils these days)
For local pick up with the drivers, I'm also offering a choice of enclosures free. These are not graded for condition, but I would say they are "fair". Note that the purchase price is for the drivers and front horns for them; you get the enclosures if you can pick 'em up and get them out of my garage.
The first is a set of Bruce Edgar designed back horns built out of a very curved laminate of wood and fiberglass. They are very heavy and you will need to pick them up. The JMLC horns in the picture are neither included nor available. The pain on them is automotive high gloss, but it was applied by yours me, so it is only so so. Another sanding and coat...
I've also used these horns with Lowthers and Voxativs + adapters. They work great, and they are configured so you can take the top off and access the throat and back chamber to make adjustments.
The second is a simple 50L plywood box, which is nicely finished on the sides in walnut veneer. You can't see the sides in the picture.
These later boxes aren't really worth anything, but you can have them.
The Edgar back horns are very special, but you have to pick them up.
Please reach out with any questions.
Attachments
Rullit vs. Lowther vs. Voxativ
Hello,
These drivers are sold, but since there are so few reports on Rullit drivers, I can offer some commentary. I've owned Lowthers and used them in a variety of enclosures. I've heard Voxativs at length and think they are basically better Lowthers in typical Lowther applications (I'm not sure they are better in front horns used at more limited bandwidth, but that's a different story). Voxativs sounded better in the upper mid/low treble, and I suspect mechanical q that is more suited toward "typical lowther" enclosures.
Rullits just sound like very even, musical wide band drivers and I think sound totally different from Lowther; I don't even find much "family" resemblance. In a normal room at normal listening distances, you could put the Rullits in a nice box or OB and listen to music, with even response from 70hz-12K+, good inner detail, extension, scale and a nice ability to capture the drama of music. I had them in 50L aperiodic boxes in corners, similar to the way AN places their speakers, and they worked great. I could listen for a long time without wanting to leave my listening seat. The work on OBs too, kind of like 755As (which I also owned), but with more scale and dynamics and slightly more top end detail. With the horns corner loaded as shown, I got extension into the 60hz, and huge scale. I only augmented them with the JMLC treble horns because I was listening at 25 feet in that room and found the trebles dropped off. The JMLCs also made it possible to have a complete soundstage entirely in front of the speakers, projected outward, if that makes sense.
Some posts on line comparing Lowther and Rullit suggest that Lowthers are "more sensitive" than Rullit drivers. I don't agree, if you are considering FR from midbass to treble. I've gotten nice sounds out of Lowthers on their own, but only through equalization of some sort and this brings their sensitivity in line Rullit, which my guess is something like 92-94db.
Here's more on Lowthers, based only on my experience using them (just opinion, not doctrine!):
Typical Lowther "horns", with very undersized mouths vs. their length don't provide enough uniform gain to the 100-300hz range to offset the driver's midrange sensitivity; the peaks of an undamped line (like a hedlund horn) can make it seem like there is mid-bass but you can tell there are issues if you listen to music with a sustained foundation in the mid bass (not drum kits, whose transients are such that it is hard to hear sustained harmonics in them rather than focusing on the beat). You can load them in a corner to improve things, but I think mltls, a tqwp etc all require equalization of some sort to play orchestral music; they hit the low notes, but still manage to sound lean. In other words, without them, Lowthers can't generate adequate response in the 80-250hz range to compensate for the huge sensitivity peak in the midrange. A design like the edgar backhorn shown, which gives you real gain in that range to me is more natural but still not quit enough; but I like my orchestra music and my classical piano with real meat on the bones. That said, it is to me a real improvement; like a gigantic minimonitor without all the dynamic compression. Caveat: I don't really mind the passive eq circuits that people insert in their lowther MLTLs to get flat response at 100hz, but I'm also not dogmatic about FR drivers vs. multiway etc. I've enjoyed them all.
I never tried the Lowthers in a big compound horn, some big corner loaded mid bass horn for the rear wave and a front horn that linearized the upper end. I suspect if I had the room, this could work well.
Ultimately, my last Lowther implementation had them in more limited frequency range, used actively with Volt woofers and and active crossover. I thought I would add a horn tweeter for a ~100db sensitivity system, but never got to that. I just got tired of such a complex system and figured that it defeated the point of the "single driver" approach.
Happy listening
Hello,
These drivers are sold, but since there are so few reports on Rullit drivers, I can offer some commentary. I've owned Lowthers and used them in a variety of enclosures. I've heard Voxativs at length and think they are basically better Lowthers in typical Lowther applications (I'm not sure they are better in front horns used at more limited bandwidth, but that's a different story). Voxativs sounded better in the upper mid/low treble, and I suspect mechanical q that is more suited toward "typical lowther" enclosures.
Rullits just sound like very even, musical wide band drivers and I think sound totally different from Lowther; I don't even find much "family" resemblance. In a normal room at normal listening distances, you could put the Rullits in a nice box or OB and listen to music, with even response from 70hz-12K+, good inner detail, extension, scale and a nice ability to capture the drama of music. I had them in 50L aperiodic boxes in corners, similar to the way AN places their speakers, and they worked great. I could listen for a long time without wanting to leave my listening seat. The work on OBs too, kind of like 755As (which I also owned), but with more scale and dynamics and slightly more top end detail. With the horns corner loaded as shown, I got extension into the 60hz, and huge scale. I only augmented them with the JMLC treble horns because I was listening at 25 feet in that room and found the trebles dropped off. The JMLCs also made it possible to have a complete soundstage entirely in front of the speakers, projected outward, if that makes sense.
Some posts on line comparing Lowther and Rullit suggest that Lowthers are "more sensitive" than Rullit drivers. I don't agree, if you are considering FR from midbass to treble. I've gotten nice sounds out of Lowthers on their own, but only through equalization of some sort and this brings their sensitivity in line Rullit, which my guess is something like 92-94db.
Here's more on Lowthers, based only on my experience using them (just opinion, not doctrine!):
Typical Lowther "horns", with very undersized mouths vs. their length don't provide enough uniform gain to the 100-300hz range to offset the driver's midrange sensitivity; the peaks of an undamped line (like a hedlund horn) can make it seem like there is mid-bass but you can tell there are issues if you listen to music with a sustained foundation in the mid bass (not drum kits, whose transients are such that it is hard to hear sustained harmonics in them rather than focusing on the beat). You can load them in a corner to improve things, but I think mltls, a tqwp etc all require equalization of some sort to play orchestral music; they hit the low notes, but still manage to sound lean. In other words, without them, Lowthers can't generate adequate response in the 80-250hz range to compensate for the huge sensitivity peak in the midrange. A design like the edgar backhorn shown, which gives you real gain in that range to me is more natural but still not quit enough; but I like my orchestra music and my classical piano with real meat on the bones. That said, it is to me a real improvement; like a gigantic minimonitor without all the dynamic compression. Caveat: I don't really mind the passive eq circuits that people insert in their lowther MLTLs to get flat response at 100hz, but I'm also not dogmatic about FR drivers vs. multiway etc. I've enjoyed them all.
I never tried the Lowthers in a big compound horn, some big corner loaded mid bass horn for the rear wave and a front horn that linearized the upper end. I suspect if I had the room, this could work well.
Ultimately, my last Lowther implementation had them in more limited frequency range, used actively with Volt woofers and and active crossover. I thought I would add a horn tweeter for a ~100db sensitivity system, but never got to that. I just got tired of such a complex system and figured that it defeated the point of the "single driver" approach.
Happy listening
Recommendations etc.
Hi,
Sure--first off, I have other Rullits and really like Oleg's drivers. They sound great and they are beautifully made. I'm only selling these to fund a different project that will involve Rullit drivers.
Rullit is not the only speaker I use (I have Altecs, monitors with Volt + Morel MDT33s and Shahinians too). Rullit fan, but not fanboy.
I've also had very good experiences with Oleg, although it is an unusual purchasing process and a buyer simply needs to accept that.
He first asks you about your musical tastes, then about your room. He also asks about how you might like to use them, and recommends horns or open baffles (though I had no trouble with a simple box). He also makes a woofer for an Onken box; these have a wood cone. Then he asks for a budget range (at least he did the first time I bought from him). He then sends you photos of the drivers a few weeks later, probably of the drivers in construction, with a few notes on operating points and sound. You pay and then get your drivers in another few weeks. You are purchasing his vision of great sound and hopefully that's aligned with what you like. There's very little information on application, but he will say what he tried and liked.
If you want measurements, and if you want to order your drivers by TS parameters, that is a 100% valid approach. Just look elsewhere. I do this too, but not from Oleg. There are plenty of great options if you want to spend 3-4K on woofers, tweeters and crossover parts from the market leaders like Scanspeak, Accuton etc. That's not Oleg's art and I will never understand why some forum comments imply that it should be. There's no law stating one must measure TS parameters, FR and distortion figures for your drivers and it doesn't make you a huckster if you don't! There's only one (simple) success factor for hifi: that the end user enjoy themselves.
I've used Rullit's in a bunch of different enclosures with Firstwatt F6 (pass made), 4p1L PSE, my own made 300B SE, my own made 2a3 SE. Different flavors, but all could keep me engaged in the music. Because the drivers are relatively easy to work with compared to Lowther or many multi-ways, you can try a lot of your own crazy ideas and actually listen to them for while. Narrow open baffle vs. wide and squat, closed box vs. vented vs. classical TL. Horns, OK! For me this is the coolest part about DIY. Build, listen, measure as possible and learn along the way.
This brings up a very cool thing about field coils: you can tweak the voltage to adjust the sound to an amp a bit. Even +/- 5% adjustments are clearly audible.
Hope this helps
Hi,
Sure--first off, I have other Rullits and really like Oleg's drivers. They sound great and they are beautifully made. I'm only selling these to fund a different project that will involve Rullit drivers.
Rullit is not the only speaker I use (I have Altecs, monitors with Volt + Morel MDT33s and Shahinians too). Rullit fan, but not fanboy.
I've also had very good experiences with Oleg, although it is an unusual purchasing process and a buyer simply needs to accept that.
He first asks you about your musical tastes, then about your room. He also asks about how you might like to use them, and recommends horns or open baffles (though I had no trouble with a simple box). He also makes a woofer for an Onken box; these have a wood cone. Then he asks for a budget range (at least he did the first time I bought from him). He then sends you photos of the drivers a few weeks later, probably of the drivers in construction, with a few notes on operating points and sound. You pay and then get your drivers in another few weeks. You are purchasing his vision of great sound and hopefully that's aligned with what you like. There's very little information on application, but he will say what he tried and liked.
If you want measurements, and if you want to order your drivers by TS parameters, that is a 100% valid approach. Just look elsewhere. I do this too, but not from Oleg. There are plenty of great options if you want to spend 3-4K on woofers, tweeters and crossover parts from the market leaders like Scanspeak, Accuton etc. That's not Oleg's art and I will never understand why some forum comments imply that it should be. There's no law stating one must measure TS parameters, FR and distortion figures for your drivers and it doesn't make you a huckster if you don't! There's only one (simple) success factor for hifi: that the end user enjoy themselves.
I've used Rullit's in a bunch of different enclosures with Firstwatt F6 (pass made), 4p1L PSE, my own made 300B SE, my own made 2a3 SE. Different flavors, but all could keep me engaged in the music. Because the drivers are relatively easy to work with compared to Lowther or many multi-ways, you can try a lot of your own crazy ideas and actually listen to them for while. Narrow open baffle vs. wide and squat, closed box vs. vented vs. classical TL. Horns, OK! For me this is the coolest part about DIY. Build, listen, measure as possible and learn along the way.
This brings up a very cool thing about field coils: you can tweak the voltage to adjust the sound to an amp a bit. Even +/- 5% adjustments are clearly audible.
Hope this helps
Just to add, I have had a pair of Silver Aero 8 speakers in my room for a couple of months now. They were left by a friend who wanted me to build a power supply for them.
In a simple OB box they are to my mind remarkable for single drivers, with good output down to 30Hz in room (helped by the room a bit). The top end isn't too extended but to my ageing ears cymbals are proper cymbals, metallic and with the right overtones that I enjoy. More importantly once the PSU is dialled in they are just so engaging and completely easy, no Lowther shout, no papery sibilance, voices, woodwind, and piano are very well rendered albeit not 'neutral'. PSU voltage makes difference, I have found a more significant determinant which is the impedance of the PSU. For anyone playing with these and using a simple bench supply or a CRC with new caps, and finding the sound a bit uneven I recommend simply adding 1-3 ohm resistors after the output caps in line. Or use ancient High ESR caps instead if that's your gig. On my friends speakers it balances the sound.
I will be sorry to see them go. Whoever bought the OP's pair which are higher up the food chain has IMO nabbed a bargain.
In a simple OB box they are to my mind remarkable for single drivers, with good output down to 30Hz in room (helped by the room a bit). The top end isn't too extended but to my ageing ears cymbals are proper cymbals, metallic and with the right overtones that I enjoy. More importantly once the PSU is dialled in they are just so engaging and completely easy, no Lowther shout, no papery sibilance, voices, woodwind, and piano are very well rendered albeit not 'neutral'. PSU voltage makes difference, I have found a more significant determinant which is the impedance of the PSU. For anyone playing with these and using a simple bench supply or a CRC with new caps, and finding the sound a bit uneven I recommend simply adding 1-3 ohm resistors after the output caps in line. Or use ancient High ESR caps instead if that's your gig. On my friends speakers it balances the sound.
I will be sorry to see them go. Whoever bought the OP's pair which are higher up the food chain has IMO nabbed a bargain.
I just took a 2W carbon comp out of the box to see if impedance mattered, a 'what if' experiment.
I'd calculate the power loss through the resistor for your coils, give a >200% margin for safety, and choose a resistor or ten, they cost peanuts. Then listen, for me it was plain as anything.
Happy to discuss via PM [emoji4]
I'd calculate the power loss through the resistor for your coils, give a >200% margin for safety, and choose a resistor or ten, they cost peanuts. Then listen, for me it was plain as anything.
Happy to discuss via PM [emoji4]
rullit supply
My recommendation would be to look at the type of supply Thomas Meyer builds for FCs. Getting a transformer with taps ever 10-20V of the center point of a range you identify, build an LCR tube rectified supply. Wire the drivers in series so you can build a typical ~300V tube amp supply. With jumpers, you can change the voltage (just don't kill yourself in the process).
Its actually a good project to learn from as well.
Sounds stunning this way.
For just checking it out, a vintage regulated linear supply sounds good too. Way better than the bench supplies you see people using.
My recommendation would be to look at the type of supply Thomas Meyer builds for FCs. Getting a transformer with taps ever 10-20V of the center point of a range you identify, build an LCR tube rectified supply. Wire the drivers in series so you can build a typical ~300V tube amp supply. With jumpers, you can change the voltage (just don't kill yourself in the process).
Its actually a good project to learn from as well.
Sounds stunning this way.
For just checking it out, a vintage regulated linear supply sounds good too. Way better than the bench supplies you see people using.
Sounds good do you know where i would get some drawings for this type of supply.
My experience is different. I think CRCRC is quite adequate and much cheaper, valves totally unnecessary but pretty. I would not run the coils in series because there is a back-emf generated in the coils when playing, and putting them in series will risk some loss of channel separation. I separated out left and right coil supplies at the last smoothing stage, otherwise it is shared, seems to work fine.
Linear regulators are an adequate place to start but are often physically noisy.
I do agree with the stepped voltage option, and I suggest people investigate the effects of output impedance on the sound, you just might be surprised.
I would also caution that not all Rullit's FCs are designed for the same voltages, the Aero 8s will run at far over 100C at 140V, they ran at 95C and rising at 120V so I switched them off. These ones need about 70-80V.
YMMV, enjoy [emoji4]
Rullit supply
Here's a link to Thomas Mayer's supply on his blog:
VinylSavor: Field Coil Power Supply with Mercury Vapour Tubes
I have no POV on back EMF and channel separation, but wouldn't rule that out either.
I will strongly second the prior post on watching the temperatures and noting that each of these drivers runs at a different voltage.
My Aeros all run at ~150V and have been doing so for years almost non stop without any issues.
If the Lab series run at lower voltages, that needs to be observed carefully. Oleg provides a recommended voltage range.
Also note: if running in a horn with a back chamber (compression chamber etc.), heat management needs to be factored in.
Good luck
Here's a link to Thomas Mayer's supply on his blog:
VinylSavor: Field Coil Power Supply with Mercury Vapour Tubes
I have no POV on back EMF and channel separation, but wouldn't rule that out either.
I will strongly second the prior post on watching the temperatures and noting that each of these drivers runs at a different voltage.
My Aeros all run at ~150V and have been doing so for years almost non stop without any issues.
If the Lab series run at lower voltages, that needs to be observed carefully. Oleg provides a recommended voltage range.
Also note: if running in a horn with a back chamber (compression chamber etc.), heat management needs to be factored in.
Good luck
I am the owner of the field coils James is building the power supply for and just to say they are the silver lab not aero. I understand aero 8 run higher voltage. Oleg is vague about voltage to the point of not mentioning it when he replied to my email just recently but did say they should be run at no more than 60 degC
james soak tested them for 6 hours at 93v and the temperature was stable at 62C. I guess he uses one like I have laser radiation.
I use an IR thermometer and scan for max temp since it varies around the coil area. I think there's a a significant chance of overheating them if run at 120V. I found voltages and temperatures as follows:
V T
72 51C
83 55C
95 63C
Anyway I find the 83V position a good figure, music is punchier and shoutier at 95V, smoother at 72. Adding 2 ohms in series evens things out, but that's only my personal preference. The supply will have switchable voltage and switchable series resistors as well so Paul can dial it in to his taste.
V T
72 51C
83 55C
95 63C
Anyway I find the 83V position a good figure, music is punchier and shoutier at 95V, smoother at 72. Adding 2 ohms in series evens things out, but that's only my personal preference. The supply will have switchable voltage and switchable series resistors as well so Paul can dial it in to his taste.
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