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Repairing/modifying Heresy II's


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Come on Carl. I know ya wanna. ;)

I mean comment on "motor boating" :)

 

 

I'd rather motor boat than comment on motor boating.

 

 

What djk says makes sense but why would it only do it with the Heresys and not the other speakers he tried on the amp? (EDIT, addressed in post 19 and I missed it).

Edited by CECAA850
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"The distortion comes out very loud and distinct in waves--something on the order of 5 hissing thumps per second."

 

Replace all the electrolytics in the 50 year old McIntoshSo((

from 1967-1973ld from 1967-1973Sold from 1967-1973Sold fro

(the sound is called motorboating)

 

https://en.wikipedia.org/wiki/Motorboating_%28electronics%29

 

The 1700 was made from 1967~1973.

 

Excellent info; Thanks!

 

That makes the speakers look like babies!  I don't think the McIntosh is the issue--it sounds fine with other speakers.

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At low volumes there isn't quite enough bass, and once you crank it up to about a medium volume, they get an awful distortion and vibration.

 

Heresy's have little bass compared to some of their siblings but they shouldn't sound distorted.  Can you better describe what you're hearing?  Is it both speakers?  have you tried the speakers with different electronics?

 

 

It's a very loud, vibrating distortion.  When you begin to turn up the volume, there is no distortion at all, but the bass does seem to be a bit weak.  With regards to power, the Mac-1700 puts out 40 watts per channel.  When the dial starts to approach 50% up, the bass breaks down into a thumpy distortion.  The distortion comes out very loud and distinct in waves--something on the order of 5 hissing thumps per second.  Originally I thought the issue was only one speaker, but the same effect hits both of them--just not in unison.  What's interesting is that if you then turn the volume down, the vibration and distortion continues, lower than the volume it was at when it started.  It seems that once the harmonic causes it to start vibrating, it wants to continue.  As you continue decreasing the volume, it eventually goes away.

 

I haven't tried the Heresies in another amp, but I have tried other speakers in the Mac, and they work fine.

 

 

Speakers just can't behave like that on their own.  So I would not worry about them.  It has to be the amp feeding them that signal.

 

Could it be that the amp is microphonic and the HII are mechanically coupled to the amp in the cabinet?

 

Another issue:  I don't know if the HII uses a low impedance woofer (4 ohms) which the amp might not like.  It could explain why other speakers work okay.

 

Edit: Bob Crites reports that the bass driver voice coil resistance is pretty much the same from the H to H11.  So I'm wrong.

 

I like djk's reference to motorboating.  The one time I heard it, it was like a purring.  But I do think that overall the amp is going to weird oscillations.  It might eventually hurt the speakers.  So be careful.

 

WMcD

 

 

Interesting.  The Mac says it will automatically handle either 4 or 8 ohm speakers.

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1985 was the switchover year between the Heresy I and II... Pictures would confirm, but the Heresy I has the woofer and horns screwed to the back of the motorboard from inside the cabinet. And the back of the cabinet is removable and screwed down.

Heresy II has a fixed, non-removable back and the woofer and horns are screwed onto the front of the motorboard.

 

 

 

pull the mid horns and make sure the drivers are snugly attached to the horn then have a good look inside and make sure that nothing is out of order. Also check the woofer dust caps that they are secure that the glue joint is solid all the way around. Not likely by start crossing things off the list and you will get there.

 

 

Be sure all screws are tight on all the drivers and terminal cup to start with.

 

It sounds like the consensus is that it's either the amp or something loose in the speaker that was creating a harmonic.

 

I think it's the second.  I started checking the speakers last night and discovered something obvious.  The speaker wire was attached to the speakers with banana plugs pushed into the back of the binding posts, but the caps on the binding posts weren't tightly screwed down.  I screwed them down tight, and the problem might be resolved now.

 

I say "might" because some people were sleeping in the house when I did this, and I couldn't crank up the speakers all the way.  They sounded great up to the medium volume I was able to go.

 

I'll test it more tonight, and will return and report with photos.

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"The distortion comes out very loud and distinct in waves--something on the order of 5 hissing thumps per second."

 

Replace all the electrolytics in the 50 year old McIntoshSo((

from 1967-1973ld from 1967-1973Sold from 1967-1973Sold fro

(the sound is called motorboating)

 

https://en.wikipedia.org/wiki/Motorboating_%28electronics%29

 

The 1700 was made from 1967~1973.

 

Yep, I think you nailed it.  I swapped the Heresy II's in my hi-fi system with the RF-52 II's in my home theatre system.  The Heresies were flawless hooked up to the Yamaha receiver, and the RF-52's fell apart connected to the Mac.

 

It's a little surprising though--from your article, motorboating is common with tube amps.  The Mac 1700 has tubes for the radio receiver, but the amp itself is solid state.  

 

The Heresies sound sweet and handled everything I threw at them with the Yamaha.  I turned the bass up all the way, turned the volume up all the way, and turned on some house music, and the speakers filled the room without a hint of a problem.

 

It looks like it's time to take the Mac to the repair shop.  Fortunately there are a couple of good ones in town.

 

Thank you guys--your help and insight was invaluable.  I'll keep in touch.

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If you're not one for working on stereos yourself, check out Audio Mart Service Center off 80th and Metcalf... Bench fee is $50 and he'll call you with an est before doing the work. He's generally pretty fair. I had him work on a few Yamaha's a while back and he did a good job. 

 

I've also checked out The Electronic Center off 79th and Metcalf (oddly enough) and would personally not recommend them.

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"The distortion comes out very loud and distinct in waves--something on the order of 5 hissing thumps per second."

Replace all the electrolytics in the 50 year old McIntoshSo((

from 1967-1973ld from 1967-1973Sold from 1967-1973Sold fro

(the sound is called motorboating)

https://en.wikipedia.org/wiki/Motorboating_%28electronics%29

The 1700 was made from 1967~1973.

Yep, I think you nailed it. I swapped the Heresy II's in my hi-fi system with the RF-52 II's in my home theatre system. The Heresies were flawless hooked up to the Yamaha receiver, and the RF-52's fell apart connected to the Mac.

It's a little surprising though--from your article, motorboating is common with tube amps. The Mac 1700 has tubes for the radio receiver, but the amp itself is solid state.

The Heresies sound sweet and handled everything I threw at them with the Yamaha. I turned the bass up all the way, turned the volume up all the way, and turned on some house music, and the speakers filled the room without a hint of a problem.

It looks like it's time to take the Mac to the repair shop. Fortunately there are a couple of good ones in town.

Thank you guys--your help and insight was invaluable. I'll keep in touch.

Really? The bass all the way up? Volume all the way up? How long do you expect them to survive?

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If you're not one for working on stereos yourself, check out Audio Mart Service Center off 80th and Metcalf... Bench fee is $50 and he'll call you with an est before doing the work. He's generally pretty fair. I had him work on a few Yamaha's a while back and he did a good job. 

 

I've also checked out The Electronic Center off 79th and Metcalf (oddly enough) and would personally not recommend them.

 

 

Thanks for the advice.  Any specific complains about the Electronic Center, or just a bad vibe from them?  I was planning on taking my Mac there--they seem to have a great reputation.

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"The distortion comes out very loud and distinct in waves--something on the order of 5 hissing thumps per second."

Replace all the electrolytics in the 50 year old McIntoshSo((

from 1967-1973ld from 1967-1973Sold from 1967-1973Sold fro

(the sound is called motorboating)

https://en.wikipedia.org/wiki/Motorboating_%28electronics%29

The 1700 was made from 1967~1973.

Yep, I think you nailed it. I swapped the Heresy II's in my hi-fi system with the RF-52 II's in my home theatre system. The Heresies were flawless hooked up to the Yamaha receiver, and the RF-52's fell apart connected to the Mac.

It's a little surprising though--from your article, motorboating is common with tube amps. The Mac 1700 has tubes for the radio receiver, but the amp itself is solid state.

The Heresies sound sweet and handled everything I threw at them with the Yamaha. I turned the bass up all the way, turned the volume up all the way, and turned on some house music, and the speakers filled the room without a hint of a problem.

It looks like it's time to take the Mac to the repair shop. Fortunately there are a couple of good ones in town.

Thank you guys--your help and insight was invaluable. I'll keep in touch.

Really? The bass all the way up? Volume all the way up? How long do you expect them to survive?

 

 

Well, it was just for a few minutes to see if I could replicate the issues I had when attached with the other amp.  The speakers seemed to have survived the test, and are now back in their home attached to the hi-fi where they can't be turned up very loud without the distortion.

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