SB acoustics kits.

I've got the 8" driver from SBA coming along with the new ring radiator dome. I'm excited to read that the SBA 8" has a shorting ring in the motor. It should have good low end performance. It has high sensitivity as well.

Cool - I'm interested to see how that 8" measures. Any idea why that spike at 1khz on SB's measurements? I'm VERY curious to see if this could be used in a 2 way...

Zero the Hero wrote:Cool - I'm interested to see how that 8" measures. Any idea why that spike at 1khz on SB's measurements? I'm VERY curious to see if this could be used in a 2 way...

SBA drivers have very stiff cones. The spike at 1k is a cone breakup so I definitely wouldn't think that this driver is a good candidate for a 2 way unless you cross steep to something like a Heil AMT at 800hz.

Taming the top end of this driver should be no problem in a 3 way, which is how I intend to use it.

A 3 way with that 8 does sound cool. Question about that break up though; their measurements of the SB15 (5") show the same breakup at 1500 hz. Are you crossing the XT25 that low?

The SB 5 has a cone breakup at 8-10k. There is a slight energy storage dip at 1.7k or so but it doesn't necessitate a crossover Fc that low. There's other ways around it to get a flat frequency response but that info is proprietary.

The SB 5 is a great value. At this price there are going to be some things that aren't perfect, but then again you get a lot of the Scan Speak performance at 1/4 the cost. That extra performance often costs a lot more which is why I have the reference series for folks that just have to have "the best." Even in that series I pick drivers that show the best performance in their respective price categories.

An earlier post noted the fact that the slanted baffle may inhibit the selling of some of these designs. I want to concur on that point and ask if your basic slanted box could be modified to more resemble, for example, the large Usher speakers? I have been interested in your projects and am especially intrigued by the slanted three ways, but have felt that the look of the box doesn't live up to the likely quality of the drivers and overall design.

There are a number of slanted speakers that are intriguing, and I think some work on the aesthetics of the box might make the difference for your slanted baffle designs. I have built the Zaph L18 which is a great project, but for my next one, I want to take Troel's advice regarding the sound of three ways and give one a try for my next project.

Hi Bob,

I appreciate your feedback. It does seem like people want a unique box or something very simple for box design. The Duet10 is a pretty challenging build, but not for the experienced woodworker. It could be modified for a 2 box layout like the Ushers as long as the baffle layout remain similar.

Since I build, measure, tweak, and critically listen to each design... a lot of these proposed changes take time to perfect. I've also been thinking of doing a Duet10 in a 2 box cabinet, but the current speaker sounds so good I'll have to wait on that until some other things get finished. I could make some suggestions if you have a drawing of what you were thinking. You could do a Duet10 with a larger facet like the Avalon or Usher and the crossover wouldn't have to change much.

Thanks for the reply. It sounds like the only limitation is my own imagination and 1) maintaining the baffle angle, 2) the baffle dimensions and 3) the volume. I have a neighbor with a wood working shop and he has agreed to help me build the boxes.

My question now is more subjective, the m5w kit is an incredible deal, but this is a lot of work, and the cost of my time is very important, so how much of an improvement are the Duet designs, and as difficult as it may to be describe, what improvements do I get if I went from the m5w to the Duet 10 ss? The Accuton drivers sound great, but I think I would prefer some forgiveness of the recording so I can enjoy my old record collection with out the analytical detail.

Hi Bob,

Before I respond in more detail, could you tell me what you have in your system presently? This will help me gauge how much resolution your speakers will reveal from the source equipment. I recently upgraded to an Ayre amplifier and it opened a whole new world of detail on top of what I thought was very very good with Aragon equipment. So, if you want the ultimate, you go all out with Accuton. If you want a bit more forgiving, you can use the Duet10SS, and if you want 85-90 percent of the Duet10SS you can go with the M5W. People pay a lot of money for that last 10 percent improvement in resolution. People pay a lot of money for a 1 percent improvement as well. It just depends on your budget and priorities. Once we identify some of your favorite music and source equipment, as well as the amplification you are using, I can give you a better lay down of all the options.

Thank you for your interest in my designs,

Jed

My current system is a Rotel RSX 1056 receiver with a Cambridge CD player and Pro-Ject Expression turntable with a pair of Zaph L18 speakers. One nice thing about the Rotel is that I can use it as a pre-amp and output the front two channels to a stand alone amplifier, which makes upgrading easy. I eventually intend to upgrade to a discreet amplifier for the mains and move the L18's to surround duty.

I tend to be very hyper and cannot sit still long enough to appreciate a speaker with a narrow sweat spot--one reason I have not pursued a ribbon tweeter design. Good off-axis response is important. Also, I am looking for a speaker that creates a very holographic soundstage.

I hear what you are saying about the pursuit of that extra 10% improvement, so its hard to know which way to go. Overall, it is for that reason that I think the the SS design may be the way to go. My time in building the design is going to be a major component so I imagine this is why I would be happier with the better drivers. However, the price of the SB design is really tempting.

What is your opinion on the value of the crossover upgrades? I tend to be a believer in using the better components, but know that many are skeptical.

BobPM wrote:My current system is a Rotel RSX 1056 receiver with a Cambridge CD player and Pro-Ject Expression turntable with a pair of Zaph L18 speakers. One nice thing about the Rotel is that I can use it as a pre-amp and output the front two channels to a stand alone amplifier, which makes upgrading easy. I eventually intend to upgrade to a discreet amplifier for the mains and move the L18's to surround duty.

I tend to be very hyper and cannot sit still long enough to appreciate a speaker with a narrow sweat spot--one reason I have not pursued a ribbon tweeter design. Good off-axis response is important. Also, I am looking for a speaker that creates a very holographic soundstage.

I hear what you are saying about the pursuit of that extra 10% improvement, so its hard to know which way to go. Overall, it is for that reason that I think the the SS design may be the way to go. My time in building the design is going to be a major component so I imagine this is why I would be happier with the better drivers. However, the price of the SB design is really tempting.

What is your opinion on the value of the crossover upgrades? I tend to be a believer in using the better components, but know that many are skeptical.

Hi Bob,

You seem to be leaning towards the Duet10SS and I think it really is something special. The next decision you will have to make is whether or not the Excel version of the woofer is worth the added cost. Honestly the L26 is a stellar performer, but if you are the type of person that will look at the woofer and wonder "how much better is the Excel," you might as well get that woofer. The excel is slightly cleaner in the midrange but they have equal bass performance. The harmonic distortion profile of each of these woofers is documented in my tests section. There you can see that the L26 starts to lose out to the W26 by about 300hz where odd order distortion is slightly less for the W26.

Your comment about a holographic soundstage makes me think of my experience with the Accuton version with Scan Speak 26W woofer (Duet10A). Holographic was one word I used to describe these speakers to their eventual owner. He's very happy with them and you can see some of his comments in the Duet10 thread. The Accuton just does something very unique with the soundstage and the detail is just incredible. It's really hard to put into words. The Scan Speak version (Duet10ss) has a lot of detail as well and is very non fatiguing. For the Rotel reciever, I'm sure it is very good but you'll definitely want to go with a separate amplifier to extract all that these Duet10 speakers are capable of. Where the the Duet10ss might have a huge soundstage, the Duet10A creates a wrap around your head soundstage. They are that good. It very well could be the last speaker you own. If you go with the Duet10ss you'll have a speaker that competes with speakers in the 10-15k range. The Duet10A is more of a cost no object or go as far as you can go type of design.

As for caps I like to use Clarity caps in the reference line. All the caps in the signal path are Clarity caps. I think they are a good value and sound great. I also do not use any electrolytic capacitors in the reference line of speakers, even values over 100mfd! For the tweeter zobel I use a Solen cap and the rest are all Clarity cap. I also use low DCR coils and air core where it is needed most. So I'm a firm believer in parts quality for the crossover without going overboard. For example, I won't use a 12 gauge inductor on a tweeter circuit if the design calls for something like an 18 gauge. It makes no sense at all the use a low dcr coil in series with a resistor to net the required resistance in that part of the circuit. Therefore I let the dcr of the coil do most of the work where it is necessary. On the woofer circuit, low dcr is a must. We have several options there. Iron core inductors have tradeoffs because of their saturation effects, and they are not as nice sounding in the midrange as say a 14 guage air core. However the iron core will have lower dcr and extract more bass. I let the customer make that call and we discuss the tradeoffs.

So, in short I'm offering what I feel is a step up in sound quality as you spend more money with the Duet10. Some of the bang for the buck is lost as you spend more money, but that final ability to create the holographic soundstage is only obtainable with the best parts. How close you want to get to that point really depends on a lot of personal choices that only you can decide on, given the right information. If you have any more questions to make sure you are as informed as possible, just let me know and we'll try to get you where you want to be with your speakers.

Regards,

Jed

Clearwave wrote:

Zero the Hero wrote:Hey Jed,

Madisound showing SB29 in stock now, just in case you're interested....

Thanks for the heads up.... I'll likely order a pair next week to try out along with the 4" and 8" drivers.

Jed

Hello group...

While we're talking drivers, (besides that SB 8") I'm interested in how the 4" shakes out... looks like it might make a dandy small midrange, but haven't seen any tests on it yet...

The 4" does indeed look special but doesn't appear to have the copper sleeve in the motor... not that this the only way to make a great motor- SBA knows their stuff, but that is one of the reasons why I'm using the 5" driver for the M5W, and an upcoming 3 way with the SBA 8".