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1972 Heresy question


MeloManiac

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I have a question about my 1972 Heresy speakers. Hope someone can help me.

Of late, one of the speakers produces a 'ziiing' sound when I listen to  a particular CD (with oud music ). When a particular note is played, there seems to be interference and a metallic 'ziiiing' sound is produced in the tweeter or squawker. Can't tell which one. It only affects one speaker, the other one is fine. For most of the other music that I listen to, the speaker is fine.

I opened the speakers and noticed two things:

The K-77 was covered with a yellowish corrosive powder (see pictures) which easily rubbed off, and it also had a loose screw (to fix to the wood panel).

 

I'm wondering if the diaphragm needs to be replaced, or if it is caused by something else, like a loose screw or perhaps the extremely dry weather which we have here right now...

Or perhaps a good clean would do the trick?

 

Help will be appreciated!

 

 

PSX_20220418_143029.jpg

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5 minutes ago, MeloManiac said:

Of late, one of the speakers produces a 'ziiing' sound when I listen to  a particular CD (with oud music ). When a particular note is played, there seems to be interference and a 'ziiiing' sound is produced in the tweeter or squawker. Can't tell which one. It only affects one speaker, the other one is fine. For most of the other music that I listen to, the speaker is fine.

Have you replaced the mid horn gaskets? Have you ensured all drivers are tightened down? If you can replicate the sound use a sock to cover the mid horn to isolate which driver is making the noise. 

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1 minute ago, jjptkd said:

Have you replaced the mid horn gaskets? Have you ensured all drivers are tightened down? If you can replicate the sound use a sock to cover the mid horn to isolate which driver is making the noise. 

Up to now, I haven't touched the horns (I did replace the caps of the crossovers). 

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23 minutes ago, MeloManiac said:

I must admit it sounds as if something loose is vibrating when a particular note is played.

That can and does happen. Sometimes it may just be something nearby that resonates. Try a tone generator and see if you can replicate the frequency. Or try the same song with a different source (something other than the CD). I've had source material produce some strange symptoms.

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CWOReilly is giving you good advice. I would check the freebies first. Back panel screwed in good and all drivers as well. The mid horn gasket gets hard over time and can make exactly that kind of noise. Something many overlook is a frequency generator. $50 bought a good used one for me off ebay and you can use them to check your cabinet and all components for buzz and rattle.

1 hour ago, CWOReilly said:

That can and does happen. Sometimes it may just be something nearby that resonates. Try a tone generator and see if you can replicate the frequency. Or try the same song with a different source (something other than the CD). I've had source material produce some strange symptoms.

Again great advice. I have some music that did just this until I gave up trying to fix or find a good copy and threw the junk out. He has covered every base for you and if all fails an ohm meter and your newly acquired frequency sweep generator will tell the tale on a bad diaphragm.

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19 minutes ago, Dave A said:

 Something many overlook is a frequency generator. $50 bought a good used one for me off ebay and you can use them to check your cabinet and all components for buzz and rattle.

 

I downloaded a free app called Signal Gen. It has been a time saver for sure.

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I'll check the gaskets this week. As I have checked all the rest, I hope this is to blame. I've noticed the screws are very tight and go deep into the wood, so those old gaskets must be very much compressed and they are 50 years old... 

 

This is one of the tracks where I hear the 'ziing' often, btw:

 

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5 hours ago, MeloManiac said:

I'll check the gaskets this week. As I have checked all the rest, I hope this is to blame. I've noticed the screws are very tight and go deep into the wood, so those old gaskets must be very much compressed and they are 50 years old... 

 

This is one of the tracks where I hear the 'ziing' often, btw:

 

That will certainly show weakness in most speakers and make nearby objects resonate. 

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10 hours ago, MeloManiac said:

 

 

I'm wondering if the diaphragm needs to be replaced,

verify the DCR of the bad sounding tweeter compared to the good tweeter ,  remove the screws , gently take out the magnet ,clean the Voice Coil gap  with air or  sticky tape ,   check the tiny leads and the solder .

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Have you tried swapping speaker channels? Left speaker to right channel, right speaker to left channel? This will tell you if it's the speaker, or something higher up in the chain (source, amp, etc). If it is in the speaker, try figuring out what driver/horn it's coming from, then swapping the driver from the working speaker to see if it's the driver. I also recommend loosening all of the terminal screws on the crossover, spraying a deoxing spray across them, and then tightening all the screws. Again, start with the free or near free steps.

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Dust and loose particles get into the drivers and resonate at certain frequencies. As already said take them apart and clean them out carefully. Inspect gaskets and treat them delicately also, you may just want to order new gaskets before doing this and just replace them as you have them apart.

 

Looking at the condition of the K77 the speakers have been in a very humid environment which grows that oxidation you see. The oxidation "powder" could even be getting into the driver and causing the buzz. I recently picked up a pair of 1975 Heresy's and was very worried about looking inside after I got them home but was very happy how clean and almost perfect all the parts were inside. I wouldn't stress out too much about yours, it's just going to take some time and a little money to get them all cleaned up and functioning good again but well worth it. I'd go ahead and do both speakers while your at it. Just worry about the mid and tweeter, you're not going to be able to clean out the K22 voice coil without removing the dust cap, it's not difficult to do but most are not up to the task of doing this on their own. I've saved many speakers from the trash by removing the dust cover and cleaning the voice coil out, somehow crap still gets in past the spider and dust cover.

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4 hours ago, dtr20 said:

Have you tried swapping speaker channels? Left speaker to right channel, right speaker to left channel? This will tell you if it's the speaker, or something higher up in the chain (source, amp, etc). If it is in the speaker, try figuring out what driver/horn it's coming from, then swapping the driver from the working speaker to see if it's the driver. I also recommend loosening all of the terminal screws on the crossover, spraying a deoxing spray across them, and then tightening all the screws. Again, start with the free or near free steps.

Yes, I did, and it is the same speaker giving the problem. Also different amps give the same problem. My SS Marantz more than my tube amp (which has more of a roll-off in high frequencies). Thank you for doing the suggestion.

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I would just get better tweeters from Crites and call it done. I dnt think you can get new diaphragms for those anymore...unless Crites has found a supplier. I would not buy them off ebay. 

Seal the back board with some thin door foam that will help all around the sound also. 

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6 hours ago, MeloManiac said:

Yes, I did, and it is the same speaker giving the problem. Also different amps give the same problem. My SS Marantz more than my tube amp (which has more of a roll-off in high frequencies). 

 Did you actually move the speakers or just swap the outputs at the amplifier? The reason I ask is I've seen cables I/C's cause problems so leaving everything the same and actually swapping speaker positions will isolate the noise to the speaker. Once that is determined time to isolate which driver is causing the noise. 

 

 If these speakers are keepers now might be the time to think about updating some of the drivers A55-g's are nice so are the B&C DE-120 tweeters. 

 

 

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13 hours ago, captainbeefheart said:

Dust and loose particles get into the drivers and resonate at certain frequencies. As already said take them apart and clean them out carefully. Inspect gaskets and treat them delicately also, you may just want to order new gaskets before doing this and just replace them as you have them apart.

 

Laughing about this. I had two buzzers that took forever to figure out. One was a bug screen that had fallen loose and in behind the dust cap. The other was a screw stuck on the woofer magnet.

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On 4/18/2022 at 8:28 AM, MeloManiac said:

The K-77 was covered with a yellowish corrosive powder (see pictures) which easily rubbed off

Could be zinc chromate. It is toxic and not used much anymore. It is/was an anti-corrosive coating used on many metals for protection. Not sure why one K-77 would have it and not the other.

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