Dunlavy SC IV A harsh high frequency


I have owned my SC IVA for many years. I replace the blown tweeters at least once a year. I know the original set were carefully matched at the factory but I can not duplicate the tecniques which John used in his shop to optimize response. The speakers sound glassy and I wonder if this is as a result of tweeters I have installed but would have been rejected by John. I have done a lot of work with room treatment,changing source, components, etc...
Are there any recommendations for fixing this issue?
Replace the Vifa tweeters with more expensive ones?
Thanks
shumi
You may want to think about having your crossovers rebuilt.
Your Dunlavy's may be 15 years old. Capacitors generally have a ten year life cycle.
So depending on use, they may need replacing.
BTW, the SC IVA is on my "Top 5" favorite speakers list!
UNless there is a known defect with the tweeters, blowing them once a year would seem, (IMO) an indication that your amp is underpowered for your needs and that you are driving it into clipping, which will fry the tweeters pretty quickly.
What kind of SPL levels do you listen at? Are you concerned to any degree about retaining your hearing? If you are harming your ears, the "glassy" sound could be associated with hearing loss. Hopefully not, but if you already have tinnitus, you may want to reconsider what you are doing, besides simply replacing tweeters.

Hopefully I'm wrong about your situation.

OTOH, if the problem is not hearing loss, there is a figurative world of difference between cheap and high quality drivers. You admit it yourself when you state the manufacturer would not accept the tweeters you are using. You are likely hearing that qualitative difference. One can attain harsh sound quite cheaply.
Swampwalker makes a very good observation :-) especially with a first order crossover design like the Dunlavy where the crossover offers very little protection for the tweeter as far a power handling goes.

Dweller, I don't think Dunlavy used Electrolytic capacitors in at least the tweeter section of the crossover, I would assume that he used polypropylene capacitors which have a much longer lifespan than the 10 years you mention. Below is a link to a informative description on a XO modification the the speaker

Dunlavy X0 Modification

Best of Luck

Peter
I ended up using the Seas Excel T25CF-001 tweeter. It spec'd out to be a perfect match to the stock tweeter.
I switched out the original tweeters to the Seas Excel after reading about Jade's modifications. I'm glad I did.

BTW: I've never blown a tweeter. If you're replacing them once a year something's not right.
Thanks for the responses guys. I am indeed concerned about my hearing. I have done a lot of bird hunting and I fear my right ear may have some damage. I need to have it checked for sure. I also listen to concert videos at 80dBs. My right front speaker blows a tweeter more than once a year. I have loved these speakers for many years but it may be time to let them go. My 9.4 system is made up of:
2 SCIVA s front LR
1 HRCC center
4 SCIII rear and LR surrounds
2 SCIs for front wides LR
I agree with Rja. Something is definitely not right if you are blowing tweeters at that rate. I have just about every speaker model John ever designed and most of the units have worked perfectly for many years without replacing a thing. I have a special attachment for the SC-IVs. I hope you can find a solution without feeling the need to replace them. I have an HT set up very similar to yours and find the synergy of an all Dunlavy system to be amazing. I am curious about your electronics??
Agree with Rja and Brauser about blowing tweeters; I had Duntech Princesses (another Dunlavy design very similar to the SC IVs) for 12 years and never blew any drivers, and I played them plenty loud. I also would like to know what electronics you're using.
All speakers are driven by Theta dreadnaught II amps.2x5 channels.
I also owned Dunlavy SC-4s, for 18 years. Never once blew a driver.
I have blown my woofers through a DC pulse, but never heard of blowing tweeters. Something must be sending a high frequency burst or you have an intermittent short, but I doubt that. You might want to post a question about how your tweeters could be blowing here on Audiogon and get feedback from more than Dunlavy fans.