I bought a pair of scivs and both tweeters are blown. I did some internet searches and this appears to be a common issue with some of these speakers. Some people blow them and some don't. Most people think it is an issue with the crossover but I never read anything definitive. Obviously the last thing I want to do is start modifying a crossover that John dunlavy spent much time perfecting. So I am wondering if anyone has any more info on solving this problem? And where can I get replacement diaphragms for these vifa tweeters. I know these tweeters were perfectly matched when they were built so I guess I am going to have to hope for the best because I do not have the capability to match them. Any info or suggestions would be appreciated!
That is a special speaker because it uses a low order (electrically 1st order) xo for the tweeter to achieve a transient perfect and phase flat response that few speakers can achieve. Don't mess with the xo as it is what defines this speaker. Replace the tweeter with the specified original and make sure you don't over driver the speaker beyond its rated limit. Others with more knowledge on this speaker can chime in but from what I have heard and read - this is a great speaker and is a classic that was ahead of its time.
I have a couple of sets of Dunlavy speakers and I have yet to hear anything better - these are gems.
I did blow the tweeters a while back but I had purchased the same tweeters for another speaker project so I replaced the cone/coil but re-used the rest of the tweeter as these speakers are individually tweaked at the factory for very flat responses - so you will likely not be able to replicate exactly the FR of the old tweeter but for me it's close enough and I can't tell the difference, and keeping the old magnet/basket is about as good as you can get.
The tweeters can still be purchased at a reasonable price:
Vifa D27TG 35 06 1" Silk Dome Tweeters | eBay
Good luck!
I did blow the tweeters a while back but I had purchased the same tweeters for another speaker project so I replaced the cone/coil but re-used the rest of the tweeter as these speakers are individually tweaked at the factory for very flat responses - so you will likely not be able to replicate exactly the FR of the old tweeter but for me it's close enough and I can't tell the difference, and keeping the old magnet/basket is about as good as you can get.
The tweeters can still be purchased at a reasonable price:
Vifa D27TG 35 06 1" Silk Dome Tweeters | eBay
Good luck!
If that is the tweeter it is still available from PE for example:
Tymphany D27TG35-06 1" Silk Dome Tweeter
Tymphany D27TG35-06 1" Silk Dome Tweeter
Best thing is probably to just buy some spare drivers and/or diaphragm kits while they are still available, as others suggest. It was a fairly common tweeter in its day.
I guess the only other thing you can do is watch your volume levels. Though they are large, they're not party speakers. They are big for accuracy not spl, and intended for audiophiles and mastering houses.
It's possible you could add some extra ferrofluid to the tweets to improve power handling, but this will influence the response curve and hence the crossover. I don't remember if Dunlavy used ferrofluid or not, but somebody does.
I guess the only other thing you can do is watch your volume levels. Though they are large, they're not party speakers. They are big for accuracy not spl, and intended for audiophiles and mastering houses.
It's possible you could add some extra ferrofluid to the tweets to improve power handling, but this will influence the response curve and hence the crossover. I don't remember if Dunlavy used ferrofluid or not, but somebody does.
The Vifa's come stock with ferrofluid cooling already. They supposedly are 100W rated drivers which is quite high, but that may be assuming a high pass filter of 12dB/oct crossover whereas the Dunlavy uses a 6dB/oct crossover. Vifa's spec sheet states that they use the IEC 268-5 18.1 standard for power which is pink noise with 6dB crest factor from 40Hz to 5kHz with a 12dB/oct slope at either end (http://www.jblpro.com/pub/technote/spkpwfaq.pdf), but the spec sheet says 2.5kHz to 20kHz test signal was used with 12dB/oct filter. I don't know where the XO point is on the Dunlavy but if a 6dB/oct filter was used that would de-rate the max power by 4x (6dB) or 100W/4=25 watts rms sustained and 100W peak power?
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Dunlavy SC-IV Tweeter Crossover
I purchased a pair of SC-IV's in 1995. I have never blown a tweeter. When I heard that Dunlavy was going out of business in 2002, I took the speakers apart so that I could order spare Vifa drivers from Madisound. I also analyzed the crossover. The primary tweeter crossover is a first order (single 15 uF cap in series with a 1.3 ohm resistor). In parallel with this combination is a resonant circuit composed of a 0.092 mH inductor in series with a 1.5 uF cap. This resonant circuit introduces a +1 dB peak at 13 Khz.
I think the 15 uF cap. in the primary crossover circuit is much larger than the value recommended by Vifa (8.2 uF). Furthermore the Dunlavy crossover does not compensate for the fundamental tweeter resonance (I measured 800 Hz). As a consequence the response of the crossover network is down a mere 5 dB over the range 600 to 2000 Hz. No wonder the tweeters are blowing up!
I purchased a pair of SC-IV's in 1995. I have never blown a tweeter. When I heard that Dunlavy was going out of business in 2002, I took the speakers apart so that I could order spare Vifa drivers from Madisound. I also analyzed the crossover. The primary tweeter crossover is a first order (single 15 uF cap in series with a 1.3 ohm resistor). In parallel with this combination is a resonant circuit composed of a 0.092 mH inductor in series with a 1.5 uF cap. This resonant circuit introduces a +1 dB peak at 13 Khz.
I think the 15 uF cap. in the primary crossover circuit is much larger than the value recommended by Vifa (8.2 uF). Furthermore the Dunlavy crossover does not compensate for the fundamental tweeter resonance (I measured 800 Hz). As a consequence the response of the crossover network is down a mere 5 dB over the range 600 to 2000 Hz. No wonder the tweeters are blowing up!
I've had my Dunlavys (pair SC-IV/A, pair Aletha, SC-1 x 3 as surround speakers) for almost 20 years now. I do wonder if there are more current speakers that are noticeably better, or as some have done, replaced the drivers with more modern ones or swapped out the crossover components with higher quality equivalents to improve the original design.
Or even a DIY equivalent of the same design principles (drivers arranged in an array, time alignment, precise crossover tuning) using better drivers and a digital crossover would be an improvement.
Just thinking out loud....
Or even a DIY equivalent of the same design principles (drivers arranged in an array, time alignment, precise crossover tuning) using better drivers and a digital crossover would be an improvement.
Just thinking out loud....
Obviously you could swap in some fancier crossover components, but I would leave them alone if I were you. I believe the crossovers used decent Solen parts to begin with. If you really must hot rod them, consider replacing the resistors with good metal oxide types, and the highpass caps for the mids and tweeters. Keep in mind sometimes this sort of upgrade can throw off the subjective musicality and balance.
If you want to play with DIY, yeah, that's a better option. Leave the poor old Dunlavy speaks alone.... That's more or less how I - and many others - always build multiways. Digital crossover might be worth a try, or just get Madisound or someone else to design a good passive 1st order crossover for you. Drivers haven't improved that much, but full ranges have. Therefore it's a pretty good idea to use one of these new smooth fullrangers for a midrange. Try a Seas dome tweeter with low Fs, and a wideband woofer of your choice. That will give you enough BW for true first order.
FWIW I have found that I prefer WMT to WMTMW formats. The latter is more dramatic, but the former is more lifelike.
I agree to leave the Dunlavy's alone - they are becoming classics and also holding their value second hand.
Regarding WMT to WMTMW the one thing I think the larger Dunlavy's do really well is provide a vertical 'wall of sound' as well as the horizontal soundstage. Their presence in the room fills the room in a way I have not heard WMT speakers do. Perhaps it isn't the WMTMW arrangement but it is a Dunlavy characteristic I notice compared to other speakers.
When I get a reasonable amount of free time I will have a go to DIY a Dunlavy like speaker. I think his patents have expired? I have built a couple of FAST systems for computer audio and these have worked out well but are small compared to designing and a building a system that will improve on Dunlavy's implementation.
I do take the occasional opportunity to listen to new high end speakers and still amazed that there isn't anything better that I have heard (with perhaps the exception of the excellent MBL systems) although I know there is a personal bias and familiarity. I'm interested in what other Dunlavy customers have moved up to.
Regarding WMT to WMTMW the one thing I think the larger Dunlavy's do really well is provide a vertical 'wall of sound' as well as the horizontal soundstage. Their presence in the room fills the room in a way I have not heard WMT speakers do. Perhaps it isn't the WMTMW arrangement but it is a Dunlavy characteristic I notice compared to other speakers.
When I get a reasonable amount of free time I will have a go to DIY a Dunlavy like speaker. I think his patents have expired? I have built a couple of FAST systems for computer audio and these have worked out well but are small compared to designing and a building a system that will improve on Dunlavy's implementation.
I do take the occasional opportunity to listen to new high end speakers and still amazed that there isn't anything better that I have heard (with perhaps the exception of the excellent MBL systems) although I know there is a personal bias and familiarity. I'm interested in what other Dunlavy customers have moved up to.
Dean
Dunlavy used soft cone material and did a great job with time alignment and transient response given that constraint.
You mentioned whos doing the same with newer materials,
That would have to he Richard Vandersteen and his new carbon/balsa wood sandwich drivers including the tweeters!
You can forget Thiel now as its a different mind set
Nobody does time alignment today better than RV
Check out the model 7
Regards
David
Dunlavy used soft cone material and did a great job with time alignment and transient response given that constraint.
You mentioned whos doing the same with newer materials,
That would have to he Richard Vandersteen and his new carbon/balsa wood sandwich drivers including the tweeters!
You can forget Thiel now as its a different mind set
Nobody does time alignment today better than RV
Check out the model 7
Regards
David
This is interesting
AudiogoN Reviews: Dunlavy Audio Labs Dunlavy IVa crossover modification
I'm not so sure spending thousands on a couple of boutique caps is wise. Is there a real effect of vastly improved sound?
I notice that the term reduction in "graininess" is often used to describe unquantifiable improvements to sound quality after swapping out components so that the sound is now "smoother" or "glass like" or "fluid like" etc.
AudiogoN Reviews: Dunlavy Audio Labs Dunlavy IVa crossover modification
I'm not so sure spending thousands on a couple of boutique caps is wise. Is there a real effect of vastly improved sound?
I notice that the term reduction in "graininess" is often used to describe unquantifiable improvements to sound quality after swapping out components so that the sound is now "smoother" or "glass like" or "fluid like" etc.
Probably not wise in the case of Vifa tweeters. Dozens of dollars may be justifiable.
Cost and quality have some relation, but sometimes $$ boutique parts sound worse. If you're a beginner with money to burn, I suppose just throwing dollars at something is likely to yield some improvements, but it's hardly cost effective. I have heard 'audiophile' systems with $$$ caps that sounded horrible, and any difference in passive xover parts was completely masked by grainy amps, source, etc. But to address your question, yes, better caps can sound better. By better I mean clearer and less audible distortion. As with many things, you tend to pay 10x (or more) for that last 1% of performance. I encourage you to compare a fancy cap with some others as a highpass on a fancy tweeter sometime.
I'll tend splurge for ostensibly mid level caps like auricaps (et al) for tweeter highpasses, and be happy with better grade solen etc for the rest.
In the case of the Dunlavys in that article, I'd venture that the resistors made more difference. Wire wound resistors usually suck compared to metal oxide, IMHO of course.
The biggest cost probably was the inductors. Those things add up fast. I would have left them stock. Sometimes simple cheap aircores sound better than fancy foil chokes. Other times it's worth it. Ferrite core are always garbage.
At some point, it's a good idea to spend a lot of hours swapping parts in an out and listening. IMO this is the only way to get a real feel for what affects what. This being the full range forum though, I assume most of the people here want to avoid passive xovers and filters as much as possible anyway...
RE graininess: For me, it is synonymous with degree of resolution. The term was probably borrowed from photography. Should show up on distortion and CSD plots. (neither of which were reasonably available to DIY'ers until relatively recently)
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Thanks for the detailed response GregB. I have a very nice tweeter I can do comparisons with someday. The Heil AMT has enough resolving power to differentiate different caps. I have a $9 film in oil motor run industrial cap. Maybe compare to a mid grade Solen or Jantzen and an electrolytic. Might be fun.
Dunlavy SC IV and crossover
I have 20 year old Dunlavy SC IV speakers. Love them. I have not used them in a while.
Today, I noticed the midrange and tweeters of the right speaker were not working. Assuming it's a crossover problem or solder. I do not have the manual.
I am not sure how to access the inside of the speaker to even get a look. I can see screws covering a plate in the back where the speaker wires connect to the amp. And, on the front, I can see each speaker subcomponent screwed in. I hate to sound so naive. But, any help would be appreciated. Thanks.
I have 20 year old Dunlavy SC IV speakers. Love them. I have not used them in a while.
Today, I noticed the midrange and tweeters of the right speaker were not working. Assuming it's a crossover problem or solder. I do not have the manual.
I am not sure how to access the inside of the speaker to even get a look. I can see screws covering a plate in the back where the speaker wires connect to the amp. And, on the front, I can see each speaker subcomponent screwed in. I hate to sound so naive. But, any help would be appreciated. Thanks.
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