Understanding John Dunlavy's Crossover Designs Crown Prince

[Remlab]

Great Dunlavy interview..Loudspeaker designer John Dunlavy: By the Numbers... | Stereophile.com
Dunlavy SC-1 measurements.. Dunlavy Audio Labs SC-I loudspeaker Measurements | Stereophile.com
Notice the inexpensive vifa tweeter's response at 1.2 khz. Ouch! I owned these, and both tweeters blew..

[xjr100]

Originally Posted by Zero Cool

I'm not trying to change anything. just duplicate the crossover boards with different parts. same exact values, different branded parts.

I suggest the following in your crossover upgrade:

1) I'd leave all coil "as it is", but maybe leave the place on new board if you decide in future to use foil coils.
2) L2 and L5 coils are used in networks for correction of freq.response, so their exact values is important (both - inductance and resistance)
3) C15 and C3 exact value is required as in (2) - but both of them making 1.504uF, so you can replace it with one 1.5uF capacitor
4) C7 and C10 also makes 1.504uF, so you can replace it with one 1.5uF capacitor
5) C6, C8, C9: replace them to 8.2+6.8+1uF
6) C4: 50uF - this should be exact value as stated in (2). For example 47+1.5+1.5
7) C1,C13,C14: 24.5uF -> 22+22+0.47 (or 20+20+2.2+2.2)
8) C2, C11, C12: I'd leave it as it is 20+10+10
9) C5, C16, C17, C18: 70uF -> 33+27+10
10) all resistors -> MOX 10W

What kind of parts to use:
If price no object, I'd use best possible caps for (5), (6) and (7) - I suggest you to try there Auricap XO.
for C3, C4, C15 quality is not so important, you can use something like Mundorf MCap250.
For (4): you can use Auricap XO, or also try inexpensive Electrolytics like Mundorf BG ("plain" - new name ECAP70)- you need to listen what is better. Not always expensive cap is better.
For Bass section I suggest MCap400, but MCap250 also will be fine and You can try here also Electrolytics - as what I've noticed that in some constructions replasing electrolytics to plypropilene in bass can make it more exact, but a bit "dry". Here you need to try and listen.

[Zero Cool]

well things are on hold. I have all new inductors and MOX resistors and got hung up on capacitors.

I was extended and offer from someone in the high end cap industry for some special caps and thats what started this whole project in motion and well you know...sometimes people say things just to make themselves look better and when you call them up to collect...they turn around and say "oh, i guess you were serious about that??" and the deal vaporizes!

So things are on hold until I can get an alternate affordable solution worked out...

In the meantime. the refoamed woofers work great. and I have been enjoying them as is with various amps, my Zen Lights mainly, various soundcraftsmens, my Atma Prototype, Audio Research VS60, my old HK 330C, even a little Dayton sonic t-amp!

[Soundtrackmixer]

Originally Posted by studiotech

This is really interesting me now. I visited a famous mastering studio last month and took my usual demo material. I felt that the presentation was rather soft on the top end and very compressed sounding for such a large system. It was Dunlavy SC-V's and SC-IVs in a 5.1 set-up. I'm wondering if those crossovers are chock full of electrolytic caps too. Performance was poor enough that I wondered if he had a compressor mistakenly plugged in the monitoring chain somewhere. I really struggled to find something complimentary to say after the visit.

Greg

I own 7 SC-V(along with two of his TSW-V tower subs), and compressed and soft are not words I would use to describe the sound of this speaker. I have the Bryston 28B SST2 monoblocks in front of each speaker, and dynamics I assure you are not an issue here.

[Remlab]

Originally Posted by Soundtrackmixer

I own 7 SC-V(along with two of his TSW-V tower subs), and compressed and soft are not words I would use to describe the sound of this speaker. I have the Bryston 28B SST2 monoblocks in front of each speaker, and dynamics I assure you are not an issue here.

All of the dunlavy speakers are basically an SC-1 with progressively larger woofers in each model. They all used the same inexpensive Vifa mids and tweets crossed over at the same point. That's why I showed the SC-1 measurements. So you can see how they all operate at that particular crossover point. An inexpensive tweeter ($28) http://www.parts-express.com/pdf/264-1022s.pdf that is only down 6db at 1.2 khz is going to distort and compress no matter how big the woofers are. Also, as Zaph stated, the Vifa 5.25" mineral filled polypropylene mids http://www.parts-express.com/pdf/297-302.pdf (Used in almost all Dunlavy models) "Are not low distortion drivers". They were used because of the very smooth, predictable rolloff characteristic..

[Soundtrackmixer]

Originally Posted by Remlab

All of the dunlavy speakers are basically an SC-1 with progressively larger woofers in each model.

You are incorrect here. The SC-1 has two mid/bass drivers, and a single tweeter. The SC-V has 2 12" bass drivers, 2 6.5" mid-bass drivers, 2 3" mids, and a single 1" tweeter. So it is not just progressively larger woofers that define the difference in his line of speakers, it was the additional of more(larger) drivers that cover smaller frequency ranges. This is important detail.

They all used the same inexpensive Vifa mids and tweets crossed over at the same point. That's why I showed the SC-1 measurements.

Unfortunately for your case, the SC-1 and the SC-V do not measure the exactly the same. As a matter of fact, the SC-1 and the SC-IV don't measure the same either. Secondly, my SC-V are the last ones he made, and he came back to my studio three times(at my expense) to change the crossovers and tweak the sound of the speakers. After these trips, the speaker sounded a lot better than they did when they first got to my studio.

So you can see how they all operate at that particular crossover point. An inexpensive tweeter ($28) http://www.parts-express.com/pdf/264-1022s.pdf that is only down 6db at 1.2 khz is going to distort and compress no matter how big the woofers are. Also, as Zaph stated, the Vifa 5.25" mineral filled polypropylene mids http://www.parts-express.com/pdf/297-302.pdf (Used in almost all Dunlavy models) "Are not low distortion drivers". They were used because of the very smooth, predictable rolloff characteristic..

Before purchasing my SC-V, I took a trip to DAL to give all of his SC line a listen. I watched as John measured quite a few drivers, and it was clear by the measurements why he picked the drivers he did. Based on that experience I learned that it is not how much the driver costs, but how they perform once they are loaded into the box. It is also noted that he updated the mids and tweeter later on, I can attest to that with my own set of speakers. He did that with the crossover as well, I can also attest to that.

I read the reviews of both the SC-1 and SC-IV. Neither review or its accompany measurements points to any distortion or compression from these drivers at their operating frequencies. As a matter of fact, at least on the SC-IV, its huge dynamics were mentioned in the review.

Just an excerpt from the SC-IVA review:

The SC-IV/A hasn't completely avoided sounding like a speaker, but, compared to the SC-IV—itself already low in speaker colorations—it sounds more like musical instruments and voices and less like an electromechanical contrivance.

The SC-IV/A's sound had tremendous coherence: despite being a complex multiple-driver system, it speaks with one voice. There is exceptional top-to-bottom integration, with no audible cues as to where in the range the different drivers take over. One visiting audiophile friend who was unfamiliar with the speakers said that if I hadn't taken off the grille to show him the drivers, he would have thought he was listening to a speaker with a single driver.

If there was any distortion like you mentioned, this would not be possible.

[Remlab]

I stand corrected. The v's are very different from the rest of the lineup.
I loved what my Dunlavy's did below 93db, but the tweeters did eventually give out. What tweeters did he update to?

[a.wayne]

Originally Posted by Zero Cool

I have no experience with LTspice so if someone wants to volunteer that would be great. I thought of using foil inductors but from everything i have read, and from what i have heard from people here and elsewhere that zero to little benefit is to be had from foil. just a lot of added cost. plus they have lower DCR so i figured that would just mess things up. I might use a foil in the woofer circuit only because finding 12ga air core inductors is hard to do, yet i can find them in foil, and on sale so that location might get a foil.

Becareful with foil inductors , completly different sonics due to there stable bandwidth linerarity. It's not as simple as swapping out value for value or matching Dcr , the voicing will be very different .....

[Soundtrackmixer]

Originally Posted by Remlab

I stand corrected. The v's are very different from the rest of the lineup.
I loved what my Dunlavy's did below 93db, but the tweeters did eventually give out. What tweeters did he update to?

I don't know what tweeter he finally settled on(never opened up the speaker), but I know it was different from the one first installed. So was the crossover once he finished tweaking.

One thing I love about John(and probably one of his biggest weaknesses as a businessman) was his almost compulsive nature at small detail in engineering, and in voicing his speakers. When he found an improvement to something, he would always come back to my studio and install and tweak it. As I said earlier, he came back to my studio four times before walking away from my SC-V - and then eventually getting too sick to return for good. When he told be that each SC-V spent 30hrs in the anechoic chamber, and being listened to and tweak, I was blow away. Makes it worth my investment to know this.

[Zero Cool]

Originally Posted by a.wayne

Becareful with foil inductors , completly different sonics due to there stable bandwidth linerarity. It's not as simple as swapping out value for value or matching Dcr , the voicing will be very different .....

I only went with foil for the woofers. that is subject to change however. for now they are on hold.

Dave