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Mighty McIntosh

Help Needed: Klipschorns with Harsh Distortion

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Posted (edited)

UPDATE as of August 1, 2020 — WHAT'S WORKED SO FAR:

 

  • I have replaced both crossovers, care of Bob Crites. Instant improvement, but still didn't sound right.
  • Then I switched from the 4 ohm taps to the 8 ohm, which changed the sound utterly (see my June 27th post).
  • I have just ordered some sound absorption panels for the ceiling (12 square feet, to start), and some Nicetown Sound Absorbing Curtains (the ones with inner felt lining). I'll report on the effectiveness of these after I install and test them.

 

___________________

 

[ORIGINAL POST:]

 

I have been given a pair of 1976 Khorns by my father. I can tell that they will sound out of this world, especially (I hope) paired with my McIntosh 240 (also from dad, 45 years ago). But initially, upon setting them up, the high and possibly the middle frequencies are washy, messy, and shrill -- painful to hear (at least at loud-but-not-harmful volume). The Khorns are replacing my Heresies, which had none of these problems with the same configuration (same components and inputs).

 

I've done a little reading on this forum, particularly here:

and here:

...and these posts have helped me suspect a few issues with my set up. (Also, see pics.)

 

  • My room is small: 15'x10', with a 7'-6" ceiling and four windows. No option to change rooms. ("SWMBO" and I have a small house, causing me almost to say No, thank you, to the offer of free Khorns. Then I slapped myself and said, Yes, thank you, O mighty father; I will make it work.)
  • There are plenty of reflective surfaces: hardwood floor, plaster walls, windows, a few hanging framed (mix of glass and plexiglass) posters.
  • There is hardly any unobstructed wall space. Can't help this, as this is my home office, and I work in it professionally (nowadays full-time).
  • The Mc240 is right next to the right Khorn (with restricted options to move it). Next to the Mc240 is the tube preamp, a Counterpoint SA 3.1 (actually paid my own money for it, used).
    • I don't understand any of the technical specifications that Chris A cites in his discussion on different amps with Khorns. I do understand what a reverb effect is. But details elude me: Is the Mc240 Class A or Class Z? High or low output impedance? Is its "first watt power" more than, less than, or equal to 1 watt?...
  • If the "Com" speaker terminal on the Mc240 (manual says "Com" = Common) corresponds to the black Khorn terminal, then I got the polarities right.
  • I am currently using the 4 ohm terminals, and haven't yet tried 8 or 16.
  • As you can see in one of the photos, the left Khorn is currently cornered between a wall to the left, and a steam radiator to the right (you can see it peeking out). I will remedy this by removing the radiator. I also plan on sealing the Khorns into their corners with closed-cell foam.
  • Funds are limited. High effectiveness-value-to-lowest-cost ratio needed.

 

I would love some suggestions. My goals are modest. I'm already happy with the bass extension, and I can tell that if I remove the radiator, it will deepen, and I have faith that sealing the corners will tighten the bass. If I can eliminate the audible distortion and get as much detail as the Heresies gave, I will be ecstatic. I've read about remedies such as wrapping the upper horns in (something...?), and/or adding sound diffusing or absorbing panels in specific places, that can help clean up the sound, but I don't know what materials these remedies would involve. I'm handy with a screwdriver and wire strippers, but my skills end there. (I've dabbled with hammer and nails, and even used a staple gun once!)

 

Good karma in advance to any who can give aid to this worthy cause.

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Edited by Mighty McIntosh
Updates on Progress
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  • Unlikely, but, the Heresies might not have revealed as much midrange distortion (different horn).  Try some other recordings.
  • Discuss with @Chris A  and @BEC
  • Treat the room
  • Change the capacitors (or have someone like Bob Crites [BEC] change them for you}.  Critesspeakers.com
  • If you work at a desk, put a soft blotter on it, or, better yet, cover the top of the desk with absorbent material, leaving it hard only where your computer sits (to not block the ventilation intakes).
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You have a bigger room and better setup than I do. Those babies should sound spectacular.

I would seriously consider adding as much sound-deadening to the room as you can.

Just my 2 cents.

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Just a lark but, do you know that your McIntosh is up to spec?  (could the distortion be up the food chain from the speaker??)

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I'm no crossover network expert but you would probably benefit from either rebuilt or new ones.

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for  the wiring of the speakers --------what size  gauge are these -------too thin would not be very good for the highs-mids and may lead these in the  screeching  issue , second thing would to use the 8 ohms terminals and on the preamp , lower the level of the treble controls until the sound is more pleasant ( if there is a tone control ) ----finally , verify the crossover to make sure all screws are tight  and replace only the capacitors , with newer ones ,  ----------there are settings on the crossover , you can lower these   by 1 tap  -for 3dl less on the tweeter -

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Come on guys, the presenting complaints are "the high and possibly the middle frequencies are washy, messy, and shrill -- painful to hear" 

 

Unless the guy is exaggerating, Do you really think this is wiring, crossover rebuild, capacitors? For instance, capacitors that built up a series resistance are going to decrease the energy in the high frequencies, That decrease would hardly be described as sounding "shrill".

 

Look at the big issues. Is it on both sides (both cabinets)? Has a test tone been run through it to determine whether it is woofer, squawker, or tweeter? Playing music (of some unspecified type) is really a rotten test signal. There are much better ways to diagnose. Personally, I would make sure that none of the drivers have been damaged. 

 

I hope this guy gets it solved without doing the "obligatory let's put new caps in the crossover". I am not unsympathetic, the OP has not been very articulate in what the exact problem is. 

 

Good luck,

-Tom

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Those caps are done...

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  • Haha 1

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20 minutes ago, Schu said:

Those caps are done...

rusty - corroded --  definitely to be gutted

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57 minutes ago, PrestonTom said:

 I would make sure that none of the drivers have been damaged.

second on that

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Looks like the K-Horn is not all the way in the corner due to the radiator being in the way? If that's true, you will not get the right sound out of the speaker. The K-Horns MUST be tight in the corners for best results. Another option would be to enclose the backs, then you can get by without being tightly sealed in the corners. Those crossovers need to be rebuilt or replaced also.

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On 6/13/2020 at 3:42 PM, codewritinfool said:

You have a bigger room and better setup than I do. Those babies should sound spectacular.

I would seriously consider adding as much sound-deadening to the room as you can.

Just my 2 cents.

 

Well, not as much as you can, but:

Thick Carpet

Absorption at the first reflection points along the wall & on the ceiling https://www.gikacoustics.com/early-reflection-points/

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Posted (edited)

Thank you all for your responses -- very helpful, particularly suggestion to contact Bob Crites, and the link to https://www.gikacoustics.com/early-reflection-points/.

 

The caps were indeed "done." I have replaced the crossovers (Crites, type AA). Much better just doing that. Below I will paste in my listening notes of each individual speaker with the old crossovers; most of those problems are now gone. I have yet to do a second extensive listening test, but the one thing I'm still noticing is over-resonant ear-piercing highs, especially on violins and flutes, less so on piano (I listen mostly to classical).

 

The speakers are still not sealed in the corners. Pipe insulation arrived just today, and radiator will be removed next Friday. I'm wondering how improvement in low freq might affect high freqs.

 

My current suspect List for piercing HF:

  • Exaggerated highs due to bass frequencies not yet being optimized with corner-sealing; i.e. highs might improve by default when bass is more focused?
  • Room problems: low ceiling, early reflections
  • Unwrapped squawkers & tweeters
  • Possible reverb with Mc240 Amp?
  • Other suspect(s) that I don't know about yet, but you might?

After I get the Khorns properly in their corners, what do you think would make the most/easiest progress toward alleviating piercing violin highs?

 

Here are my listening notes for the Khorns with old crossovers. Like I said, most of the following problems have vanished with the replacements from Bob Crites.

 

All descriptions will be impressionistic, based on my years of listening to mostly classical and a little jazz. Though I’m 59, with a some age-appropriate hearing deterioration (at 4k: 3db, 6k: 4db, & 8k: 2db), my ears are well trained in listening to music, and still good enough to easily choose a pair of Music Hall Marimbas over the price-equivalent Cambridge speakers for my second system.

Left speaker (the one near the radiator):

  • I have yet to hear a violin sound on this speaker that is tolerable. Top end sounds like they have escaped from their smooth sphere and run wild: knife-like and harsh, they sound too high, because they’re not well contained (read on for what I mean by this). Especially in Brandenburg Concerto #2, when the trumpet and violin play their high notes together, they stop sounding like a trumpet and violin, which would sound contained, respectively, in their proper spheres of sound. Instead, they sound like an indistinct screech that hurts my ears, and would, if I were on the bridge of USS Enterprise, cause me to sink to my knees with my hands over my ears.
  • On Trevor Pinnock’s recent (excellent SQ) Brandenburgs, a solo violin sounds like its being played inside a metal lunch box.
  • Anonymous Four (an ethereal, female a cappella quartet, specializing in early music) sound like they’re singing through Radio Shack speakers. They were recorded in a resonant space, but I can’t hear the space, only the harsh mid and upper echo-tones of their voices. The space is flattened.
  • There are fuzzy edges to sustained notes, and pointillist spray in staccato notes (think Georges Seurat, when what we want is Rembrandt).
  • Clarinet (Mozart quintet) has no air, and some brassiness on its edges.
  • Bass in a recent recording of Brahms’ piano concertos is boomy, but I’m supposing that the speaker being away from one wall might be causing that.
  • Overall, sound from this speaker lacks body compared with the right-side speaker. Hard to tell if this is simply not being snug in its corner. The effect I’m hearing is not simply bass extension (which is reduced, compared to right speaker), but rather fullness.

Right Speaker (the one next to the Mc240):

  • Sounds “fuller” than left speaker.
  • Overall impression is that the sound is washy, indistinct.
  • There is a little more air with wind instruments.
  • On Trevor Pinnock’s recent Brandenburgs, the same solo violin (see above) sounds like its being played inside a church.
  • Anonymous Four’s a cappella sounds life like; can hear space around them. But the edges are frayed. They sound like they all have a cold. So the space in this recording sounds rough, unrefined. There is not a single bell-like tone in a recording of bell-clear vocalists.
  • High end is not as high as the left speaker, but there is some screechiness, with occasionally what sounds similar to feedback. When I cover the Mc240 with a cardboard box with a sweater thrown over it, this seems to improve, at least a bit.
  • Midrange edges sound jagged, and the insides of notes sound jangly.
  • High and mid frequencies sound like they’re spitting. Yeah: everything sounds like Daffy Duck conferring his lisp to every instrument.
  • Timpani on Brahms’ 1st piano concerto sounds a little muffled, like a bass drum with a blanket piled inside it.

So, I guess my overall impression is that the speakers, together, sound subpar: super-loud, all-over-the-place, messy, undetailed, mostly low-resolution, screechy behemoths with moments that betray out-of-this-world potential. My Heresies, with the same set up, sounded fantastic. (And now my living room TV sounds fantastic, because I moved them there.) The Heresies had terrific detail, great resolution, and passable bass, and I could listen to them for hours. Listening to the Klipschorns is a struggle from note one: immediate fatigue with, even recoiling from, the sound. As I’ve been writing this paragraph, a 4½-minute movement from Brandenburg #4 is really getting to me. I’ve lowered the volume, and it’s still hard to listen to: scratchy, making me react just a little like I do when fingernails scrape a chalkboard. The speakers sound no better at low volume.

Edited by Mighty McIntosh

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Wow, it's still a mystery to me!

 

I agree, a lack of bass balance can make mids and treble sound over emphasized.  Sealing the Khorns into the corners may well help.  Although it depends very heavily on the room, Klipschorns often show a dip at 60 Hz or 70 Hz, but recovers by the time it gets down to 48 Hz.  I often run mine with the bass control at + 6 dB.

 

I, too, listen mostly to classical music, and, occasionally jazz, and played in several orchestras.   I get a lot of detail, and love what the mid and high frequency response does with orchestra bells, triangles that float in space, the purity of the treble end of the piano, brass, etc.  To borrow from J Gordon Holt, the Khorns do, indeed, trigger my musical gestalt.   As to violins, they sound just right about 60% of the time, close to correct about another 20%, and too "steely" about 20% of the time.  My Pagannini set sounds incredibly good except for a single selection, V1, #1.  Did they fix whatever was wrong after the first selection?  Many times the gutty string sound is very detailed and very near what I used to hear in the orchestras (~~ 15' to 25' away), and also much like the sound of a violinist who performed for us in the room our sound system is in.    They always have been difficult to record; Leo De Gar Kulka thought so to the degree that when he finally heard them right (using the Colossus recording system) he had to yell out in the control room, "The strings! The strings!

 

Placing a highly absorbent pad where a yardstick placed flat on the front grille would touch the side wall, and reaching two feet farther into the room is recommended by some (see the post "Corner Horn Imaging" by @Chris A on this forum). image.png.c9e6db906cf42d996c33b2a49f7657dd.png

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On 6/13/2020 at 6:16 PM, PrestonTom said:

Come on guys, the presenting complaints are "the high and possibly the middle frequencies are washy, messy, and shrill -- painful to hear" 

 

Unless the guy is exaggerating, Do you really think this is wiring, crossover rebuild, capacitors? For instance, capacitors that built up a series resistance are going to decrease the energy in the high frequencies, That decrease would hardly be described as sounding "shrill".

 

Look at the big issues. Is it on both sides (both cabinets)? Has a test tone been run through it to determine whether it is woofer, squawker, or tweeter? Playing music (of some unspecified type) is really a rotten test signal. There are much better ways to diagnose. Personally, I would make sure that none of the drivers have been damaged. 

 

I hope this guy gets it solved without doing the "obligatory let's put new caps in the crossover". I am not unsympathetic, the OP has not been very articulate in what the exact problem is. 

 

Good luck,

-Tom

 

I agree with Tom's observations 100%. I'm not a tech, engineer, or golden ear, but I'll give my 2 cents anyway.

 

Look at the rust on the caps, coils, squawker magnets, etc. If the outside looks like that, what about corrosion inside the voice coils of the squawkers and tweeters?

I would ask Crites test those 4 drivers before chasing room treatments.

 

Secondly, I agree with Coytee regarding the McIntosh MC-240. It takes less power to get a painful sound out of Klipschorns than Heresy's, so you're listening to a fraction of the first watt coming out of the MC-240 with the Klipschorns, and it has to be squeaky clean. You're listening with a bigger lens that magnifies every imperfection in the signal. So even though the amp sounded fine with the Heresy's, it still could be contributing to the problems with the Klipschorns. Maybe a helpful forum member lives nearby and they could bring over a substitute amp to find out if that improves the sound.

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On 6/19/2020 at 3:01 PM, Mighty McIntosh said:

I have yet to do a second extensive listening test, but the one thing I'm still noticing is over-resonant ear-piercing highs, especially on violins and flutes, less so on piano (I listen mostly to classical).

In the room that you show that they're in presently, this isn't that far away from my Khorn clones in a 13'x11'x8' room--which have never sounded very good, especially with the type of music that you say that you listen to (the type of which comprises about 1/3 of my own music library). 

 

I personally don't believe that you're going to get the Khorns into good listening shape for your room anytime soon even with significant refreshing of passive crossover network components and even perhaps the drivers themselves.  I'm actually sorry to say it, but I've heard the same issues with Khorns for years (including the Khorn clones I own and have significantly altered now).  Even with tri-amping, time aligning, and replacement of the tweeters and midranges (drivers and horns), there is still an issue for me listening to them in the small room (even with ESS AMT-1s on top).  I don't listen to them in my computer room, in reality. 

 

I would recommend that you tidy these Khorns up and then place them on craigslist or ebay (setting a minimum acceptable bidding price of perhaps $1K). 

_______________________________________________________________________________________

 

Based on your listening preferences and my experience with Khorns trying to get them to sound good on classical recordings, I'd recommend replacing them with a fully horn-loaded pair of Jubilees (biamped with active crossover) or Danley Synergies (with passive crossovers and good for mono-amping)--something in the SH-60 to SH-96 range, or the equivalent molded "SM" series Synergy horns having 60 degrees or greater of horizontal coverage.  Anything that has good sound for solo violin and string orchestra will require loudspeakers having very low phase/group delay growth.  That really narrows down the list of fully horn-loaded loudspeaker models that can do the job.  I currently use Jubilees and a center K-402-MEH, all time-aligned with flattened SPL and phase response and the results are really outstanding in my main listening room (15.5'x40'x9').

_______________________________________________________________________________________

 

Alternatively, you can give up the horn loading (...I wouldn't do this...) and go for a higher efficiency studio monitor design having flat phase--like a pair of JBL M2s, but these will be very expensive--much more expensive than stock Jubilees with a Xilica XP-4080 DSP crossover.  Direct radiating studio monitors aren't very exciting to listen to, mainly due to the very high levels of compression distortion and modulation distortion when playing classical music at realistic performance levels.

 

Chris

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13 hours ago, triceratops said:

Look at the rust on the caps, coils, squawker magnets, etc. If the outside looks like that, what about corrosion inside the voice coils of the squawkers and tweeters?

I would ask Crites test those 4 drivers before chasing room treatments.

 

Good logic. The squawker magnet on the other speaker (the one I didn't photograph from the rear) is even rustier. I will check in with Bob about this.

 

13 hours ago, triceratops said:

Secondly, it takes less power to get a painful sound out of Klipschorns than Heresy's, so you're listening to a fraction of the first watt coming out of the MC-240 with the Klipschorns, and it has to be squeaky clean. You're listening with a bigger lens that magnifies every imperfection in the signal. So even though the amp sounded fine with the Heresy's, it still could be contributing to the problems with the Klipschorns. Maybe a helpful forum member lives nearby and they could bring over a substitute amp to find out if that improves the sound.

 

The MC240 was serviced by Mike Urban at his Vintage HiFi Museum. Specifically:

Previous upgrades (power supply + signal path) by Analogique

Clean controls & switches thereby eliminating hum / buzz

Surface cleaning

Tubes tested

Add (4) NOS vintage GE 6L6GC tubes to replace incorrect & weak 5881WXT quad

Voltages check OK

Install correct fuse

Audio & functional testing

Power plus distortion tested (20Hz to 20KHz) = 50 watts!

Total Harmonic Distortion plus Noise (THD+N) @ 1%

And Mike's partner-in-tubes, Bob Pienkowski, serviced the Counterpoint pre-amp at the same time.

 

Nevertheless I like the idea of testing the Khorns with a different amp, which I have -- another tube amp (a good quality modern one) that I bought from the Vintage HiFi Museum.

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On 6/19/2020 at 4:01 PM, Mighty McIntosh said:

 

So, I guess my overall impression is that the speakers, together, sound subpar: super-loud, all-over-the-place, messy, undetailed, mostly low-resolution, screechy behemoths

ok  we'll get you an answer very quickly as to the Problem -now follow my reasoning

 

-  you say the Heresy sounds great ---ok ,,    you can go ahead and swap the  Midrange K55V and the K77  Tweeters from your Heresy Speakers if they are the Heresy 1  -----------into the Khorn , and swap the drivers from the khorn into the Heresy -

 

that will tell you 1)  if the mids and highs of the Khorn sound equally bad on the Heresy , or not -

 

and 2)  if the Khorn  sounds better with the Heresy mids and highs -----

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Yes, may as well try that other tube amp as it is Handy.

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2 hours ago, RandyH 000 said:

ok  we'll get you an answer very quickly as to the Problem -now follow my reasoning

 

-  you say the Heresy sounds great ---ok ,,    you can go ahead and swap the  Midrange K55V and the K77  Tweeters from your Heresy Speakers if they are the Heresy 1  -----------into the Khorn , and swap the drivers from the khorn into the Heresy -

 

that will tell you 1)  if the mids and highs of the Khorn sound equally bad on the Heresy , or not -

 

and 2)  if the Khorn  sounds better with the Heresy mids and highs -----

 

The small rubber washer that is between the midrange driver and the mid horn in both the Khorns and the Heresy I may be partially deteriorated.  They may fall apart or crumble a little when switching drivers.  Ask Bob Crites where to get new ones (you'll need 4).  He may have a supply. 

 

P.S., I had Khorns in a room with a floor plan of only 9' x 11' 4" but with a high ceiling.  They sounded wonderful from the one, narrow, sweet spot.  The room was very diffuse and also had a thick rug and a big slab of 4" anechoic wedge Sonex behind my head (that was only about 7" from the wall).  Of course, they sound better now, in my current big room.

 

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