Help with Dunlavy SC-IV signature

@cerberus79,  good that you got to the bottom of the problem, even after no longer owning the speakers.

I enjoyed a pair of Duntech Princess speakers for 19 years and would like to clarify a few points here.

John Dunlavy began his speaker business, Duntech, in Texas before moving it to Australia.  That company continues in business under other ownership.

His Duntech models were high quality in design, components, and build.  John believed in time and phase coherency and based his designs on that.  But my Princesses were rated at 90 dB which may have misguided some.  The manual recommended at least 200 wpc "for musical enjoyment" and I found that to be true.   The best match I found was with VTL 300 monos, and later Parasound JC-1 mono amps.

At one point John returned to the US to begin building a new Duntech model.  My assumption was his concern over the high shipping costs from OZ because of size and weight, so a model built in the US could be more competitive.  However it was not a sales success and John separated from Duntech to begin another company, Dunlavy Audio Labs (DAL), located in Colorado Springs.  There he designed and began building a new line of speakers, based upon their sibling Duntech models.  These were the SC series mentioned here by others.  The DAL speakers became highly successful for both home and studio applications.  So I'm not surprised that your buyer found inappropriate crossover modifications to be the culprit for the poor performance.  John's engineering prowess led to the crossover designs which were critical to the sonic success all of his models. 

When John's health began failing he sold DAL, but the continuation of the brand was not successful and the company closed after about a year.  For those with adequate space and appropriate components I believe both Duntech and DAL models can provide great musical satisfaction, when found used in good condition.

@cerberus79 Somebody messing with the crossovers would explain a lot of things. John and team measured every single raw driver and entered all the measurements into a computer, computer-selected a set of matched drivers to build a pair of speakers, then tweaked every crossover in real-time to get the measurements he wanted, that were within a certain tolerance of his reference. Every single completed speaker, even within a matched pair, has slightly different values for the crossover components.

The reason I have two pairs of SC-V is because the first pair I bought showed up with dead tweeters and mids. The seller claimed they were fine when he put them into storage a year earlier, but didn't test them before he built a crate and shipped them to me from East Bridgewater, MA to Cedar Rapids, IA. He refunded me money to cover the cost of replacement drivers from Madisound, but obviously they weren't matched like they were from DAL. They sounded great when I got them going again, even better than my SC-IVs, but it always bothered me that they weren't matched like when they left the factory. I never did figure out the cause of the dead drivers; they all measured open, but didn't smell like voice coils were burnt. 

Another pair of SC-Vs showed up on eBay about 1-1/2 years later for a really good price, I figured if I didn't buy them I'd kick myself for years to come, and talked myself into buying them. I rented a cargo van from Enterprise and made the drive from Cedar Rapids to Irvington, NY to pick them up from mastering engineer Joe DiGiorgi. I'm extremely happy with them, and they'll be the last pair of speakers I ever need. Surprisingly, despite the replacement drivers in the 1st pair, both pairs sound very close, the main difference being slightly better imaging on the 2nd pair. JD changed from dome mids to cone mids during production, somewhere around serial number 150 from what I've found by looking at every available pic of SC-Vs I can find on the internet, and I suspect that has more to do with the slightly improved imaging than the replacement drivers. My first pair are 117-A/B, second pair are 198-A/B. 

 

Duntech/DAL crossovers -  The crossover board on my Duntech Princess was accessed by a removable panel on the back of the cabinet.  Once opened the board could be slid out since mounted on drawer rollers.

A friend of mine with design background was curious to see that crossover so I opened it up for him.  He exclaimed, "All it needs is a transformer and it would be as complex as an amplifier."  I don't have an electronics background but that board was stuffed with parts and looked complex to me!