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Old 12th July 2011, 06:28 PM   #1
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Default Acoustat 3- MK121C

Hi,
i have Acoustat 3, think that is the medalion model MK121C
i want to replace the capacitors and the voltage multiplier & if is possible to improve the xover.
this is the schematic i have, there is any thing that could be done better
thanks for your time
best regards
williams
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Old 12th July 2011, 08:11 PM   #2
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the caps in the multiplier? sure. NPO, high voltage type.

There is a suggested change to the level control wiring -think it has been posted, search?

The HV coupling caps are hard to beat. Also been discussed...

I got rid of the speaker fuse - you may not wish to defeat this.

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Old 12th July 2011, 08:34 PM   #3
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hi,
thanks bear,
what do you mean by control wiring, the rheostat for the highs?
i want to replace it by two resistors, do you know the best setting-values?
the 0.01uF/6KV i can get ceramic caps. are good for it?
williams
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Old 12th July 2011, 10:38 PM   #4
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Quote:
Originally Posted by Williams Audio View Post
the 0.01uF/6KV i can get ceramic caps. are good for it?
You might contact Moray James as he sells Polypropylene caps to replace the Acoustat Polyester caps with the proper AC voltage rating.

There are some more details about these capacitors in his posting here:
Acoustat 1+1 high sound level limits
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Old 13th July 2011, 02:06 PM   #5
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Yes, I meant the big "pot" for HF level setting.
There is another way to wire it, might be better...

The HV caps, if the ufd value is about the same, sure... higher voltage yields a longer life.
But the life stock is >20yrs now...

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Old 13th July 2011, 06:54 PM   #6
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If your interface was built (or upgraded) to the 'C' version, you have the latest and greatest configuration of the xover network. Replacing the variable resistor with fixed resistors is not a bad idea, esp. since the variable control is subject to corrosion. There is no 'correct' value - that's why it's variable. Find a setting you like, and then replace the two parts with 50-watt fixed resistors - it's just a voltage divider across the HF transformer. You might also consider changing out the 47-uF electrolytic to a polypropylene type - this is probably the most significant change you can make.

I doubt there is much (if any) sonic advantage to replacing the HV multiplier caps. Ceramic discs are a good choice here. I would leave those alone.

If your interface contains 0.01-uF 6kV polypropylene coupling caps (and they almost certainly do - that's all that Acoustat used in these interfaces) then you have the best type for the job. Unless you are having problems, I would leave those alone as well.
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Old 14th July 2011, 05:57 PM   #7
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With all due respects to AcoustatAnswerMan... btw do you have a super hero cape?

The HV ceramics are likely at the end of their useful life.
I've had to repair a fair number of interfaces whose caps got very leaky, and also may have caused the early demise of the HV diodes. So I would highly recommend the highest breakdown voltage NPO type HV ceramic caps you can find for that slot... the exact value is non critical as long as it is close to the original ufd value. So, imo, a good idea to replace them since it's inexpensive to do so. Just make sure the supply is off and bled down before proceeding.

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Old 14th July 2011, 06:40 PM   #8
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My intention in suggesting that the HV multiplier caps needn't be replaced was that there is no point in upgrading them to a different type of capacitor. Certainly, if there is any suspicion that they are failing, or if you just want to make sure, then there is no harm in replacing them with the same or similar type of capacitor.

As for the super hero cape, yes, I DO have one, with a big 'A' on it for Acoustat. I feel extremely priviledged to have worked with Jim Strickland at Acoustat, and get a lot of satisfaction from continuing to help Acoustat owners maintain their speakers. Very few speakers, ESL or otherwise, can boast of the continued good performance and reliability that Acoustats exhibit so many years after manufacture.

And thank YOU Bear, for your continued support and inspiration.
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Old 14th July 2011, 10:36 PM   #9
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Goody, glad you got the official cape!

Wonder which color you got?

I only have a junior AAM cape, myself... a little small when I put it on, but still...

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Old 15th July 2011, 09:46 AM   #10
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hi all,
For the connection of the panels, I have four pieces of ceramic 0.01uF 10KV, I think designed for use in high voltage & high freq, size 75x35x4 mm flat profile wrapped in yellow plastic film, can not clearly read the brand name,
Is better capa polypropylene then ceramics for application in acoustat?
ceramic sure better in higher frequencies, but here for this application I'm not sure
Best regards
Williams
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