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Crixx

Heresy I distortion on 2nd harmonic

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Hello everybody, this is my first topic and I'm glad to partecipate at this forum. I'm owner of a fantastic pair of Heresy I (1976), with k-22 woofer, k55-V mid e k22. tweet. 

To improve the acoustic of my room, I record the frequency response of a single speaker with a calibrated microphone (i use REW). What I see  is an elevatate distorsion of 2nd order between 3000hz e 6000hz. You can see it the graph below. It is common in both the speaker. So I switch with another amplifier, but the problem persist. The measurement is near the speaker (70 cm), so i can  exclude the ambience problem. In the listening I perceive marked sibilant. I think that is a problem of my speakers, but perhaps it is a common situation in Heresy I. Has anyone tried to measure the distorsion?

Second, if the problem is finite to my speakers, which is the cause? 

In the capacitor of the crossover (It is a type D converted to Type E)?

In the gasket of the speaker?

I don't know. Can anyone help me?

Thank you in advance

distorsione_78cm.jpg

Edited by Crixx

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Well, first of all, second harmonic distortion is not even audible to the best ears until you have a few percent of it, and even then it doesn't sound like distortion at all. Most people can't tell anything until it is well above 5% and approaching 10%. So, measuring less than 0.15% is very good.

 

As far as hearing sibilance, you can check a few things.

 

Open the backs (and be careful because the crossover has connecting wires that feed to the back panel).

 

- first, confirm the polarity of the mid-horn and tweeter connections are reversed in polarity compared to the woofer... in the type "D" it was not like that (all the polarities were the same), but Klipsch noticed in testing a slight improvement with reversing the polarity of the mid and tweet connections with respect to the woofer. The Dope From Hope Vol 15 No 1 may 1, 1975 has the explanation and diagram. All Heresys with a serial number after 14N517 have this change and the new crossover is called the "E" type.

Since yours are D converted to E, this is just to verify the polarity was right (check both speakers).

 

- check and re-tighten all the screw connections on the terminal strip of the crossover

 

- unscrew the mid drivers from the mid horns to check the little gaskets. They look like the little rings you put in the end of a water hose to prevent leaking. If they are not cracked they are likely OK and don't even need to be removed. The driver is heavy, so be very careful not to cross-thread when taking it off or putting it back on. When you put the driver back on it should be "gentle firm tight", not screwed down very hard.

 

See if any of these things help. If not, it may be that the crossovers are just old and the caps have gone bad.

Visit this site and then call Bob Crites ( 479-967-1542  ) to find out what do do.

 

 

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Looks like the crossover point is 4500hz?  I'm not sure.  If so, then the distortion spans both the squawker and tweeter.  Either something is buzzing and needs to be tightened down or replaced like Pauln said above, or the crossover needs help.  If the crossover point is 6000hz, then it's probably localized to the squawker.

 

How long ago did it get converted from a type-D to a type-E?

 

Here's a nice article about replacing squawker gaskets:  https://steveneudaly.wordpress.com/2013/09/08/klipsch-heresy-type-e-capacitor-replacement/

 

I had a brand new K77 tweeter that was throwing distortion.  I carefully took it apart and reassembled everything.  Distortion was gone.  I think it was the bug screen vibrating.  Before and after pics below:

 

K-77-D left.png       K-77-D-left-repaired.png

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Thank you for yhe answers. 

Pauln unfortunately the distorsion is between 2 and 3,5% in the range 3500 4500 hz. It's true that the 2nd harmonic isn't very annoying, but probably is connected with the excess of sibilant. 

I reverse the polarity of the tweeter an mid no more than a month ago, but the problem there was even before with type- d wiring. 

I'm going to check all the screw and the condition of the gaskets.

Finally, I write to Bob Crites and he thought that it could be a crossoverr problem and probably he is right. But is the crossover point at 6000Hz, so I think that is a midrange problem. 

 

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If it's the same distortion on both speakers, and the crossover point is 6K, then my guess is either 1) the midrange gaskets are both old and need replacing, or 2) the crossovers are old or something got jacked up when the crossovers were converted from type-D to type-E.  Do you know when this was done and who did it?

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" distorsion is between 2 and 3,5% in the range 3500 4500 hz "

 

Try stuffing a sock in the tweeter.

 

If that fixes it, change to a type AA tweeter section.

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I don't own these speakers but, turning down the volume levels, using EQ in the upper midrange or a change in driver components are some things to try.

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I see, the worst case is at about 4.3KHz where the distortion attenuation is least, about -30dB... so just over 3%.

 

What are you using for a source?

 

 

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9 hours ago, pbphoto said:

If it's the same distortion on both speakers, and the crossover point is 6K, then my guess is either 1) the midrange gaskets are both old and need replacing, or 2) the crossovers are old or something got jacked up when the crossovers were converted from type-D to type-E.  Do you know when this was done and who did it?

I converted the crossoverit one month ago, but I had the same distortion even with type D. Change only the frequency response

 

8 hours ago, pauln said:

I see, the worst case is at about 4.3KHz where the distortion attenuation is least, about -30dB... so just over 3%.

 

What are you using for a source?

 

 

To misure the distortion I use an  audio card Emu1212m which has a vary good DA and AD conversion. 

Edited by Crixx

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On 1/17/2017 at 8:11 PM, djk said:

" distorsion is between 2 and 3,5% in the range 3500 4500 hz "

 

Try stuffing a sock in the tweeter.

 

If that fixes it, change to a type AA tweeter section.

 

There ya go!

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