Harshness in Mission 752 and 753 Loudspeakers
Sirchtelbo
have commiserated about the harshness they have experienced with these
loudspeakers. I am posting this because after three years of optimizing the
rest of my system and still experiencing problems with my Mission 752s, I have
found a solution that works for me.
After many trials of using various felt surrounds, removing the tweeter
screens, weighing down the speakers, trying various spiking and blu-taking
arrangements, alone and in combination--often ameliorating the problem but
never coming up with a treble that matched the 752s marvelous midrange, I have
found that the following actions, by themselves, completely solve the problem
and result in a far cleaner, detailed, extended and yet more relaxed and
coherent-sounding loudspeaker than I would have believed possible. I can now
listen to these speakers in my fairly bright-sounding room for hour upon
pleasurable hour with no listening fatigue.
I take no credit for these ideas--rather I gleaned them from the writings of
Harvey Rosenberg and others on various lists, and just applied them to the
Missions.
1. Move the crossover outboard of the speaker cabinet.
2. Replace the stock capacitors and resistors with equivalent high-quality
Hovland (tweeter) and Solen (woofer) capacitors and Caddock resistors.
A good friend, who is both an electrical engineer and formerly a successful
U.S. speaker and phono cartridge designer, eyeballed the new crossovers and the
generic parted-out components, then listened and pronounced the results
excellent. He further recommended replacing the stock ferrite-core inductor in
the woofer crossover with an equivalent air-core inductor, which will be less
likely to saturate and distort at high power levels. I am currently attempting
to obtain the inductor inductance and resistance values from Mission.
I believe owners of the old 752s will be pleased, and I imagine these changes
would work well for 753 owners as well, at least in the tweeter crossover.
Certainly, for me, these speakers have moved from an excercise in
approach/avoidance to the point where I can't see myself giving them up for the
forseeable future.
To bad Mission didn't make a "signature" edition.
John Woodgate
<sirch...@aol.com> inimitably wrote:
>1. Move the crossover outboard of the speaker cabinet.
>
>2. Replace the stock capacitors and resistors with equivalent high-quality
>Hovland (tweeter) and Solen (woofer) capacitors and Caddock resistors.
I would advise caution. There seems no obvious reason why these changes
should affect the reported 'harshness', which AIUI is usually blamed on
the tweeter itself. Of course, there *could* be a design fault. Maybe
the woofer magnet is too close to the ferrite-cored inductor. (;-)
--
Regards, John Woodgate, OOO - Own Opinions Only.
Phone +44 (0)1268 747839 Fax +44 (0)1268 777124.
Did you hear about the hungry genetic engineer who made a pig of himself?
Sirchtelbo
dramatic as they were.
I made the modifications in stages, first putting the crossovers outboard, then
replacing the capacitors and resistors. Moving the crossover outside did
indeed rid the speaker of much of its harshness, so there may be something to
what you say about a magnetic interaction.
However, some harshness remained on such high frequency transients as, for
example, plucked steel guitar strings. Replacing the crossover components
ridded the speaker of the above effect and also banished a pronounced silvery
smear in the treble that I had attributed to the tweeter itself.
The psychoacoustic effect seems to be that instead of, at some level,
ignoring/overlooking/compensating for distortions in the higher frequencies by
concentrating on the midrange and bass, I now find myself listening deeply into
the music, seeking out and revelling in the clarity and detail of plucked
strings, shimmering guitars, eerily realistic vocal sibilants, etc.
It may be serendipitous, but the improvement is equivalent to replacing the
loudspeaker with a much better model--it's that pronounced. And the parts only
cost about "one hundred English pounds!" Go figure.
Regards,
Chris Noblet
John Woodgate
<sirch...@aol.com> inimitably wrote:
>The psychoacoustic effect seems to be that instead of, at some level,
>ignoring/overlooking/compensating for distortions in the higher frequencies by
>concentrating on the midrange and bass, I now find myself listening deeply into
>the music, seeking out and revelling in the clarity and detail of plucked
>strings, shimmering guitars, eerily realistic vocal sibilants, etc.
That is consistent with a reduction in high-frequency intermodulation
distortion. This is interesting. What sort of capacitors were they that
you took out? Electrolytic? I've never disassembled a Mission, so I
don't know what they used. And were the resistors wirewound types?
I would suspect that good quality 'normal' components would produce the
same effects, without the cost of the 'exotics' that you used. But the
configuration might be such that one or more components is super-
critical.
I'd like to get my hands on an unmodified one to do some measurements.
Sirchtelbo
distortion. This is interesting. What sort of capacitors were they that
you took out? >>
All the resistors and capacitors were labeled "MicroPride"
<<Electrolytic?>>
The woofer crossover capacitor is a light metallic blue cylinder about an inch
long, 3/8-inch diameter (about 1/8 the volume of the cap with which I replaced
it), wires protruding from each end. The cap in the tweeter crossover is
potted with some yellowish epoxy-type material into a white ceramic box. It
is even tinier in comparison with its replacement (not that size matters, of
course...)
<<I've never disassembled a Mission, so I
don't know what they used. And were the resistors wirewound types?>>
Just like the cap in the tweeter crossover, they were Potted with yellow glue
into little white ceramic boxes.
<<I would suspect that good quality 'normal' components would produce the
same effects, without the cost of the 'exotics' that you used. But the
configuration might be such that one or more components is super-
critical.
I'd like to get my hands on an unmodified one to do some measurements.>>
I'd be glad to send you the clipped-out components, except for the air-core
inductor in the tweeter circuit, which I'm continuing to use.
Regards,
Chris Noblet
stevenc...@gmail.com
Brian Gaff
think the former?
Brian
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<stevenc...@gmail.com> wrote in message
news:312491b5-4c7e-4a4c...@googlegroups.com...
Trevor Wilson
> Hi, I've tried changing caps etc in my 752's but cannot see what value the cap in the hf side is! All it says is 65 k (I think) Could you say what they are please? Mission website just ignores mail!! Thanks!
>
guess. You could either measure it, or post a photo to the web.
HOWEVER, why do you imagine that swapping a cap will reduce/remove
"harshness" from a speaker?
Before you start doing anything to the speakers, you should:
* Describe the room, including furnishings. Is it a 'live' room?
* What sort of music are you playing? Are you playing the highest
quality source material you can find, or some old punk rock cassette
tale you found in a dumpster? The source material matters! Big time.
--
Trevor Wilson
www.rageaudio.com.au
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Phil Allison
--------------------
>
> **I'd guess that 65k suggests a 6.5uF cap. But that is very much a
> guess. You could either measure it, or post a photo to the web.
>
> HOWEVER, why do you imagine that swapping a cap will reduce/remove
> "harshness" from a speaker?
>
> Before you start doing anything to the speakers, you should:
>
> * Describe the room, including furnishings. Is it a 'live' room?
> * What sort of music are you playing? Are you playing the highest
> quality source material you can find, or some old punk rock cassette
> tale you found in a dumpster? The source material matters! Big time.
>
Almost all stories of "harsh sound" are the result of using bad recordings ( ie worn vinyl) and a bad ( ie reverberant) room.
The same system and speakers sound completely amazing to their owners when these two problems are fixed - it not that hard to do, at least temporarily.
I was once able to feed live sound from a microphone to a living room stereo system and the result was a level of sound quality never previously heard.
Fiddling about with expensive leads, fancy capacitors and magic devices is a fool's pastime which distracts from the real solution.
..... Phil
Dave Plowman (News)
> Almost all stories of "harsh sound" are the result of using bad
> recordings ( ie worn vinyl) and a bad ( ie reverberant) room.
--
*I'm not being rude. You're just insignificant
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To e-mail, change noise into sound.
Phil Allison
---------------------------
>
> Or fried drive units. ;-)
>
>
Not that either is one bit relevant.
Nor that the pommy cunt gives a fuck either.
Maggots have already eaten most of his tiny brain.
... Phil
Jim Lesurf
> In article <161ced97-f162-422f...@googlegroups.com>, Phil
> Allison <palli...@gmail.com> wrote:
> > Almost all stories of "harsh sound" are the result of using bad
> > recordings ( ie worn vinyl) and a bad ( ie reverberant) room.
> Or fried drive units. ;-)
Jim
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Dave Plowman (News)
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stevenc...@gmail.com
Phil Allison
----------------------------
> If it was more specific & stated what value it was I wouldn't need to
> ssk the question!
As to equipment mainly vinyl never played on out worse than an era turntable(best i could afford at the time, 40 years ago, fitted with SME3009 s2 imp with shure v15 3 cart marantz and various amps over the years:- goid enough?
>
>
** Well, I too used to be the proud owner of a V15-3 cart, until I invested in a Sony CDP101 in 1983.
Surprising to me and others, who visited my home, was that the massive leap change of technology did not produce a very great tonal difference.
That Shure cart, carefully set up and loaded with the correct R and C values was damn near flat.
The biggest & most obvious change was the silky, quite background that all tracks emerged from, compared to vinyl - plus super clean bass and bugger all distortion.
Google tells me your Mission speakers use silk dome tweeters, which are known for pleasing sound quality, unlike some metal dome types.
You do own a CD player ?
Try listening on good headphones - it may easily be that the same tracks sound pretty harsh on them to.
If so, they would exonerate your Mission 75xs.
... Phil
stevenc...@gmail.com
Trevor Wilson
> No, the 752 have metal dome tweeters! I'm considering going the route of going to "Willys hifi" who do an exchange system with silk domes for £90ish! I do have a cd player Marantz 6006 uk edit! I just prefer vinyl! I have some old Koss pro cans that do prove the harshness with the missions,i have a pair of Jbl l20ts that ive recapped +some newer Quad 12 l's (i rarely sell my old kit) but i just love the missions, but yhey are tiring for longer listens, cheers
>
excellent. Although I am unfamiliar with your speakers, I note that you
have declined to respond to my earlier questions. Answers to those
questions would allow us to assist you further.
stevenc...@gmail.com
József Vajda
> rest of my system and still experiencing problems with my Mission 752s, I have
> found a solution that works for me.
>
> After many trials of using various felt surrounds, removing the tweeter
> screens, weighing down the speakers, trying various spiking and blu-taking
> arrangements, alone and in combination--often ameliorating the problem but
> never coming up with a treble that matched the 752s marvelous midrange, I have
> found that the following actions, by themselves, completely solve the problem
> and result in a far cleaner, detailed, extended and yet more relaxed and
> coherent-sounding loudspeaker than I would have believed possible. I can now
> listen to these speakers in my fairly bright-sounding room for hour upon
> pleasurable hour with no listening fatigue.
>
> I take no credit for these ideas--rather I gleaned them from the writings of
> Harvey Rosenberg and others on various lists, and just applied them to the
> Missions.
>
>
> 2. Replace the stock capacitors and resistors with equivalent high-quality
> Hovland (tweeter) and Solen (woofer) capacitors and Caddock resistors.
>