Hales Revelation 3 Crossover Help

what kind of problem are you having? 

I took my speakers to a fellow to have the tweeters rebuilt, while they were there he ordered new crossover caps.  Evidently they are now incorrectly rewired and there is a lack of midrange and dramatically lowered output.  Don't know if both were worked on at once and somehow got incorrectly repaired.  At this point I have paid more than I originally purchased the speakers for and now they sound worse than when I sent them in.  He is willing to try and make them right, but I fear without a schematic it's going down a troubling path. 

Hahahaha. Hahahhaah. Hahahhaa.

I’m laughing because I may be the only person on earth who knows what happened, because most modern speaker designers have never seen it.

What he probably did was swap out electrolytics for film (a good thing) that were parallel to the woofer. As a result, he lowered the ESR without compensating with the appropriate resistor.
If they are gone, measure the speaker impedance and compare to the Stereophile measurements. You’ll see a gnarly dip. Add R until that goes away.

If you can do neither, add R in 0.5 Ohm increments. Usually you want around a total of 1.5 to 2 Ohms (existing resistor + ESR).

You owe me a bottle of tequila.

Best,

E

PS - Based on the STereophile measurements here:

https://www.stereophile.com/content/hales-revelation-three-loudspeaker-measurements

That speaker is already very difficult to drive. Even small variations can perturb it further. Also, because it’s such a difficult speaker, I would have done a complete analysis first, to see if there are opportunities to improve the impedance curve while maintaining the frequency response. Old Gensis / Infinity speakers notoriously benefit from this type of work.

Erik_Squires
Would this explain why he said they measured out at 3 ohms when he was done?  Thought they were 4ohm nominal?

This speaker uses 4th order crossovers with all film on top. The concept that Erik is referring to should not happen with smaller tweeter caps when only tweeter caps are replaced.
There have been at least 2 other threads where the ESR issue was raised.... I say at least, because on 2 occasions, I received private messages from the ops looking for help to work through the problems. Each issue was different. First Verify that the correct replacement diaphragm was used also If the diaphragms got to hot putting them in, that can make the changes that you are referring to. I don’t drink, how about a hamburger.

According to the impedance curve posted, these speakers used a 4 ohm woofer and most likely a 6 ohm mid and tweeter. The woofer at one point drops to below 3 ohms, this is most likely why you are reading a 3 ohm dcr. Nominal means no more than average impedance over its operating range.
Also,  the method that Erik is referring to,  you would add the appropriate resistor to the tweeter only (wherever the caps were replaced)

I appreciate the responses!  I informed the person that worked on them so that he can read through your thoughtful answers.   Unfortunately, I have zero skills as far as speaker repair.  Originally I tool them in because the tweeters were getting increasingly harsh sounding and he confirmed that the ferrofluid had began to fail and was solidified.  
I am unsure exactly what capacitors were replaced.   I can build a house or fix just about any outboard boat motor out there but knew better than to attempt messing around with the Hales.  
He is a knowledgeable person with a good reputation.  We're just trying to get through my issue so I can back to listening and not thinking about speakers and systems. 

This speaker uses 4th order crossovers with all film on top. The concept that Erik is referring to should not happen with smaller tweeter caps when only tweeter caps are replaced.

Pretty much true, though I could imagine if a zobel or notch filter was employed it might.


I was referring to the general use in a low pass filter. Ideally you'd use something like DATS to measure the speaker impedance and that of the components that were removed. That would give you a definitive answer.



Best,

E