When I actually listen to the D2608 and the SB26CDC side by side, the SB26CDC tweeter is a clear winner!
I feel confident that Joe can iron out the the lumps and bumps in the SB tweeter's response
It will be well worth the effort
All the best
Steve
I feel confident that Joe can iron out the the lumps and bumps in the SB tweeter's response
It will be well worth the effort
All the best
Steve
Okay,
You want a drop in exchangeable replacement for the existing form factor tweeter.
Interesting how the absence of the phase plug causes the notching at ~9kHz. You might consider adding a phase plug to the wave-guide.
Another what if to consider: adding a waveguide may also cause an increase in distortion. Adding the waveguide narrows the coverage angle at the crossover frequency; air pressure increases and air velocity also increases. The thermodynamics of +/- air compression and veloicty is not linear. This is a major contributor to the distortion signature of Compression Drivers. (2nd HD, 3rd HD and IMD)
Thanks DT
DT,
Is the notch happening because of the lack of the tweeter phase shield or more likely because that Joe's WG (wave guide) is not suitable for the SB26CDC tweeter?
IIRC Joe removed the phase shield (PS) to achieve a better mechanical fit with his WG; The Augerpro WG has both PS and no PS option, and looking at the FR curve for both, it does not indicate that the removal of the PS results in a drop in the 9KHz region for those WGs.
Is the notch happening because of the lack of the tweeter phase shield or more likely because that Joe's WG (wave guide) is not suitable for the SB26CDC tweeter?
IIRC Joe removed the phase shield (PS) to achieve a better mechanical fit with his WG; The Augerpro WG has both PS and no PS option, and looking at the FR curve for both, it does not indicate that the removal of the PS results in a drop in the 9KHz region for those WGs.
Joe's waveguide has a 10 year history of being perfectly fine.
What I think could possibly going on is that in this case at ~ 9000Hz the wave length and the diameter of the waveguide throat are such that sound from one side of the tweeter diaphragm and the other side (or center) of the diaphragm add up like 1 + (-1) and cancel or null out each other (out of phase with each other). The same thing happens in a compression driver without a phase plug.
There is nothing magic about 9000 Hz. That happens to be where the stars line up for this waveguide and tweeter diaphragm pair.
Thanks DT
DT,
Interesting hypothesis.
Joe,
You mentioned modifying the existing Elsinore wave guides - any thoughts on mods to accommodate the SB26CDC with phase shield in place?
Interesting hypothesis.
Joe,
You mentioned modifying the existing Elsinore wave guides - any thoughts on mods to accommodate the SB26CDC with phase shield in place?
The 9KHz null is created by the fact that the waveguide does not get in far enough. The problem is an improper fit in the throat, it was after all designed for a very different tweeter. But the key is that the diameter is right, but the profile of the 'shoulder' is, for want of a better word, to fat to get in far enough.
I have sent samples to Steve 'smort1' and we are going to shave some of the shoulder and make it a sharper profile. This should get the throat of the waveguide right inside and no more gap. It will then be sent back to me and see/measure what result we have. But the phase thingy has to go, it is the only way to get rid of that gap.
But I keep coming back to the issues of lower sensitivity and lower Z of the SB26CDC, how will that work out when used in the Elsinores?
At least I have figured out some things, I have sorted out the low passes (2) of the "NBAC" driver and it looks like the result is a crossover around 3.3KHz (this is what it predicts, but it should be reasonably close and tweakable) and the low bass has a 3mH series inductor, the midbass has 0.68mH series inductor, followed by an LCR to ground 0.39mH/4R7/1.2uF. This gives us the combined, all four drivers at 2m and 15° off axis:
Other than tweaking the 0.68uF, this should hopefully also work with the SB26CDC. The LCR, the R value can be further tweaked, but the LC values look good.
The next two graphs is for those of you who are likely to be interested.
These are the various and combined responses of the two pairs of "NBAC" drivers:
The Grey line is the same as the Red above. The Red here is the top two drivers, there is no 7KHz bump. So the 5R looks just right. The Green is the bottom drivers, the 4KHz suckout is purely acoustic effect that I take advantage of (one of my original ideas going back to Mk1). The rounded 7KHz peak is uncorrected here, that was my decision to leave it. Can I change my mind about that later? Maybe.
Next one speaks for itself, these are the crossover only with acoustic data:
Again Grey is the combined , Red is the MidBass and the Green is the Bass. You can see the effect on the LCR on the combined and Red responses, but you can see the absence on the Green Bass.
The bottom line is that I have the "NBAC" combinations well sorted, if adjustments are required for the SB26CDC, I am in a good position to adjust accordingly.
So I will be looking forward to get the modified waveguides back when Steve is able. Then we continue the story...
I have sent samples to Steve 'smort1' and we are going to shave some of the shoulder and make it a sharper profile. This should get the throat of the waveguide right inside and no more gap. It will then be sent back to me and see/measure what result we have. But the phase thingy has to go, it is the only way to get rid of that gap.
But I keep coming back to the issues of lower sensitivity and lower Z of the SB26CDC, how will that work out when used in the Elsinores?
At least I have figured out some things, I have sorted out the low passes (2) of the "NBAC" driver and it looks like the result is a crossover around 3.3KHz (this is what it predicts, but it should be reasonably close and tweakable) and the low bass has a 3mH series inductor, the midbass has 0.68mH series inductor, followed by an LCR to ground 0.39mH/4R7/1.2uF. This gives us the combined, all four drivers at 2m and 15° off axis:
Other than tweaking the 0.68uF, this should hopefully also work with the SB26CDC. The LCR, the R value can be further tweaked, but the LC values look good.
The next two graphs is for those of you who are likely to be interested.
These are the various and combined responses of the two pairs of "NBAC" drivers:
The Grey line is the same as the Red above. The Red here is the top two drivers, there is no 7KHz bump. So the 5R looks just right. The Green is the bottom drivers, the 4KHz suckout is purely acoustic effect that I take advantage of (one of my original ideas going back to Mk1). The rounded 7KHz peak is uncorrected here, that was my decision to leave it. Can I change my mind about that later? Maybe.
Next one speaks for itself, these are the crossover only with acoustic data:
Again Grey is the combined , Red is the MidBass and the Green is the Bass. You can see the effect on the LCR on the combined and Red responses, but you can see the absence on the Green Bass.
The bottom line is that I have the "NBAC" combinations well sorted, if adjustments are required for the SB26CDC, I am in a good position to adjust accordingly.
So I will be looking forward to get the modified waveguides back when Steve is able. Then we continue the story...
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Hello,
It wasn't me that spoke of "modding the Elsinore waveguide."
If I were to do some" modding" of the waveguide it would be in small increments.
First I would increase the diameter of the waveguide throat just enough to clear the structure of the phase thing on the SB tweeter.
Next step: (I did this step when I mocked up a Visaton WG 148 R and attached it to the SB tweeter.)
Roll up a ring of molding clay or blue tack stuff and squeez it between the waveguide and tweeter. It surprised me how well the parts stuck together and stayed put. The blue tack stuff pushed out a bit into the throat of the waveguide. I removed the excess blue tack from the waveguide throat with a made by me sort of putty knife tool made from a popsicle stick.
Edit: this filled the gap.
A bit more ambitious "modd" would be a completely new waveguide spun up on a lathe. Same thickness same diameter as before, it will be a bolt on aftermarket waveguide that will drop right into an existing enclosure. The current waveguide is a shallow cone with straight sides. Remember a flat tweeter has wide 180 degreeish coverage at the crossover frequency. The cone shape waveguide narrows the coverage angle and likely begins to cause reflections. If I was making a waveguide on a lathe I would think about putting a ellipse shape curve rather than the straight line slope of a cone.
When it comes down to it this is Joe's waveguide, after a lot of thought he will do what he likes best.
Thanks DT
DT,
Where did I say/imply that you suggested modding Joe's waveguide?
I only commented "interesting hypothesis" to your post on the phase shield.
We already know that Joe is working on the mods (from his earlier post), and hence asked him the question directly, and he has replied sharing what he and smort1 are doing.
Where did I say/imply that you suggested modding Joe's waveguide?
I only commented "interesting hypothesis" to your post on the phase shield.
We already know that Joe is working on the mods (from his earlier post), and hence asked him the question directly, and he has replied sharing what he and smort1 are doing.
No worries DT, good discussion going on, and look forward to developments from Joe in the coming days.
I too am trying to keep with the latest swirls of post.
But I think we have reached some level of clarity now, about what we are going to do.
It is now up to Steve to do what he knows needs to be done. When I get waveguides back, I will of course post the measurement(s) and we can all compare.
But I think we have reached some level of clarity now, about what we are going to do.
It is now up to Steve to do what he knows needs to be done. When I get waveguides back, I will of course post the measurement(s) and we can all compare.
Considering the interest in the SB26CDC, some good views of the faceplate assembly and so forth - https://www.diyaudio.com/community/threads/sb26cdc-is-this-okay.400468/
Hello all,
it is done, the Elsinores are singing and I would like to tell you a little more of the whole story.
I had started my audio career with Gauder Akustik Vescova speakers (with Accuton ceramic drivers) combined with electronics rather on the fast, analytical side. Then I switched to Reference 3A La Suprema (full-range drivers with tweeter and woofer support) on Pass Labs and Classé Audio amplifiers and made myself comfortable in the warm, cozy corner. Then, with conversion to beryllium tweeters in my La Supremas, the liveliness returned somewhat and the desire for more drive and even more liveliness increased. I then continued to walk the fine line between warmth and analytics.
Fortunately, I hit the mark with the subsequent elaborate DIY of an Allen Wright RTP3D preamp and his DPA-300B monoblocs. They combine "Pace, Rhythm And Timing" with a pronounced naturalness, for which "warmth" starts to become the wrong, too one-dimensional term. The point had come when I also got the desire for further development in the above sense on the loudspeaker side. Now that Allen's concepts have gotten me this far, what could be more natural than to jump on Joe's Elsinore project?
So, then it was off to the terrain of wood construction, which was completely new to me. In my hometown Kiel, there is an open woodworking shop where my colleague and me rented space and were able to get at least the body of the cabinets up and running pretty quickly.
With the body in place, it was off to the living room at home. My patient wife I will probably remain eternally grateful that she has lovingly tolerated the weeks-long construction site on the carpet. The veneering, flush milling, sanding, oiling, sanding, oiling, etc. took a lot of time, but the balancing of the 40kg heavy sound furniture on the balcony and back for all the dusty work steps was a great fitness program for the back.
Now they are at their destination and could be heard for the first time on the weekend. The external crossover is only provisionally wired and it will soon get its own narrow stand housing. In the course of the next year, I will probably rebuild this again with my favorite components.
And what are the first impressions?
It was important to me that the speakers disappear completely and can no longer be located. The Reference 3A La Suprema already did that very, very well and I didn't want to compromise on that. The big relief after the first tones from the Elsinore: Wow, this works just as well. The space between the speakers is filled without a break, a nice stage builds up. The bass doesn't reach quite as deep, but is dynamic and fast. The mids were already fantastic with the Reference 3A due to the full range driver, but the Purifi drivers are in no way inferior. The treble bundles through the waveguides a bit more, which is good in my acoustically not optimally treated listening environment.
All in all, the Elsinores thrilled me right from the start. I actually got the hoped-for increase in sense of pleasure, dynamics and expressiveness. They harmonize perfectly with the virtues of the DPA-300B and RTP3D preamp. If I ultimately listened to a limited spectrum of favorite music with the Reference 3A, the Elsinore directly made me want to discover new music. They simply convey the musical variety more naturally and self-evidently, without becoming annoying. In retrospect, I noticed that the full-range drivers had imprinted their own sound signature, which did not always go well with every type of music, and that's how my favorite musical pieces emerged.
Regarding the tweeter: I don't miss the beryllium tweeter of the Reference 3A in any way, even though the change a few years ago was a revelation at that time. Detail and airiness are just as present with the Elsinores. In fact, I was skeptical at first that I would miss anything. But Joe is right, it really is worth listening to the tweeter in the Elsinores before judging.
Of course, it's difficult to completely block out the euphoria and pride in what we've created ourselves when it comes to making sound judgements. However, a nice sign for me was that our eight-year-old made himself comfortable in the sweet spot for the first time and listened devoutly to the currently playing album "Layers of Life" by the Emil Brandqvist Trio for surely half an hour.
Joe, I want to express my gratitude for this great project. You have created something extraordinary.
P.S.: The tea towel under the speaker is for easy movement, the Isoacoustics Gaia feet otherwise adhere immovably. Not a design feature forever...
it is done, the Elsinores are singing and I would like to tell you a little more of the whole story.
I had started my audio career with Gauder Akustik Vescova speakers (with Accuton ceramic drivers) combined with electronics rather on the fast, analytical side. Then I switched to Reference 3A La Suprema (full-range drivers with tweeter and woofer support) on Pass Labs and Classé Audio amplifiers and made myself comfortable in the warm, cozy corner. Then, with conversion to beryllium tweeters in my La Supremas, the liveliness returned somewhat and the desire for more drive and even more liveliness increased. I then continued to walk the fine line between warmth and analytics.
Fortunately, I hit the mark with the subsequent elaborate DIY of an Allen Wright RTP3D preamp and his DPA-300B monoblocs. They combine "Pace, Rhythm And Timing" with a pronounced naturalness, for which "warmth" starts to become the wrong, too one-dimensional term. The point had come when I also got the desire for further development in the above sense on the loudspeaker side. Now that Allen's concepts have gotten me this far, what could be more natural than to jump on Joe's Elsinore project?
So, then it was off to the terrain of wood construction, which was completely new to me. In my hometown Kiel, there is an open woodworking shop where my colleague and me rented space and were able to get at least the body of the cabinets up and running pretty quickly.
With the body in place, it was off to the living room at home. My patient wife I will probably remain eternally grateful that she has lovingly tolerated the weeks-long construction site on the carpet. The veneering, flush milling, sanding, oiling, sanding, oiling, etc. took a lot of time, but the balancing of the 40kg heavy sound furniture on the balcony and back for all the dusty work steps was a great fitness program for the back.
Now they are at their destination and could be heard for the first time on the weekend. The external crossover is only provisionally wired and it will soon get its own narrow stand housing. In the course of the next year, I will probably rebuild this again with my favorite components.
And what are the first impressions?
It was important to me that the speakers disappear completely and can no longer be located. The Reference 3A La Suprema already did that very, very well and I didn't want to compromise on that. The big relief after the first tones from the Elsinore: Wow, this works just as well. The space between the speakers is filled without a break, a nice stage builds up. The bass doesn't reach quite as deep, but is dynamic and fast. The mids were already fantastic with the Reference 3A due to the full range driver, but the Purifi drivers are in no way inferior. The treble bundles through the waveguides a bit more, which is good in my acoustically not optimally treated listening environment.
All in all, the Elsinores thrilled me right from the start. I actually got the hoped-for increase in sense of pleasure, dynamics and expressiveness. They harmonize perfectly with the virtues of the DPA-300B and RTP3D preamp. If I ultimately listened to a limited spectrum of favorite music with the Reference 3A, the Elsinore directly made me want to discover new music. They simply convey the musical variety more naturally and self-evidently, without becoming annoying. In retrospect, I noticed that the full-range drivers had imprinted their own sound signature, which did not always go well with every type of music, and that's how my favorite musical pieces emerged.
Regarding the tweeter: I don't miss the beryllium tweeter of the Reference 3A in any way, even though the change a few years ago was a revelation at that time. Detail and airiness are just as present with the Elsinores. In fact, I was skeptical at first that I would miss anything. But Joe is right, it really is worth listening to the tweeter in the Elsinores before judging.
Of course, it's difficult to completely block out the euphoria and pride in what we've created ourselves when it comes to making sound judgements. However, a nice sign for me was that our eight-year-old made himself comfortable in the sweet spot for the first time and listened devoutly to the currently playing album "Layers of Life" by the Emil Brandqvist Trio for surely half an hour.
Joe, I want to express my gratitude for this great project. You have created something extraordinary.
P.S.: The tea towel under the speaker is for easy movement, the Isoacoustics Gaia feet otherwise adhere immovably. Not a design feature forever...
HenSch,
Congratulations on your successful build, the speakers look beautiful.
If I understand correctly, you are playing them with your tube amps now?
Congratulations on your successful build, the speakers look beautiful.
If I understand correctly, you are playing them with your tube amps now?
Thank you very much for your kind words!
Yes, they are played with the tube amps, push-pull 300B monos built on the DPA-300B from Allen Wright.
Yes, they are played with the tube amps, push-pull 300B monos built on the DPA-300B from Allen Wright.
HenSch,
Allen Wright 300B push pull mono-blocks should be a fine choice - what is the output power?
Allen Wright 300B push pull mono-blocks should be a fine choice - what is the output power?
I've biased the 300B quite low, having 24W dissipation per tube. This makes roughly 10...15W maximum output power I would guess. The Elsinores are quite sensitive, I could not drive the amps into clipping even at higher than even comfortable level.
That is not a bad idea. The amp should still go pretty loud into the ULD Elsinores. Have you found that to be the case?
Brian Gurr in Auckland, New Zealand, he also has a pair of DPA-300B and an RTP preamp too - he bought the kits and put it together himself, becoming well versed with the innards. Allen designed the DPA-150 afterwards and that was more powerful, but importantly even better sounding again. I was visiting Brian in 2016, about five and a half years after Allen's passing away, and Brian had heard the 150 when he visited Allen around 2009. Brian and I have the schematic of the 150 and only a handful of people have that schematic. Brian was wondering if I could help him design an amp like the 300B because he knew that I had done the earliest prototyping in an old Dynaco ST-70 EL-34 amplifier and that I could do an EL34 version. But I said that was not the way to go, that we should look at Allen's 150 design, but I was not going to copy his circuit, but that the key thing that Allen had done was to go "beyond triode." I immediately thought, we should call the amplifier "Beyond Triode" and we could make the point that Allen was the first one to go "Beyond Triode" in the 150. The downside is that the output tubes have >2 gain, but now has a much lower and stable impedance into the Primary of the output transformer. Brian did build some and also with my direction, made changes to the 300B as well. But the front-end has to have incredibly high gain. So I had to design a new front-end circuit. So this is what we are listening to now and it is a step above the 300B. But there is something that you could do to the 300B, just a Brian did to his. But you now need a preamp with gain, but your RTP should be able to cope with that.
I gather Thomas in Schaffhausen could make to a DPA-150 amplifier, but it would be incredibly expensive. How deep are your pockets?
Hi Joe,
the ULD Elsinores go really loud even with 10 watts, way beyond a comfortable or even bearable level. Although I can hear significantly louder with them before the room is overloaded, everything stays just clean, controlled and un-shouty even at high volumes.
Your insight into the further developments of Allen is highly interesting. I will keep with my DPA-300B for sure, having spent countless hours and quite some money into the build, going into the full with the careful choice of components and the external power supply design. I'm incredibly happy with the result and thus there's no itching for any change.
the ULD Elsinores go really loud even with 10 watts, way beyond a comfortable or even bearable level. Although I can hear significantly louder with them before the room is overloaded, everything stays just clean, controlled and un-shouty even at high volumes.
Your insight into the further developments of Allen is highly interesting. I will keep with my DPA-300B for sure, having spent countless hours and quite some money into the build, going into the full with the careful choice of components and the external power supply design. I'm incredibly happy with the result and thus there's no itching for any change.
