Restoration: Miller & Kreisel Sound (M&K) SV-200B tower loudspeakers

If you're not familiar with this speaker model, you're not alone...because neither was I. These are in fact M&K SV-200B's, built in the mid 1980's. For those of you who need to catch up, here's some background info in a thread which was started when I first found these guys --> https://www.audiokarma.org/forums/showthread.php?t=519388

> Part 1 - plate amp rebuild <

As you can see from the previous thread, the electrolytic caps on the amps were in bad shape. Two fully corroded through legs on different caps, prevented the one amp from working properly. Using the Volkswoofers was a no go. So, this became a project and put on the back burner, since I had no extra funds for these at the time.

However, I did apply some Watco Rejuvenating Oil to the cabinets at that time, which made them look like new again. I also re-glued the foam padding down above the woofers, which was peeling off. Then for Christmas 2013, I had the 12" woofers re-foamed as a gift. Slowly but surely, this project was going to be finished. :yes:

Fast forward to last week, when I FINALLY ordered all new parts to rebuild the plate amps and power supplies of the Volkswoofer 2B portion of the speakers. The parts list included the following:

- Elna Silmic II electrolytic caps; throughout amp
- Nichicon Gold Tune (KG) Type-II electrolytic power supply caps; bumped up from 7200uF to 8200uF
- Vishay ceramic safety power supply caps
- Vishay zener diodes
- Vishay ultrafast rectifiers; upgraded from 1N4002 to UF4002
- Vishay/Dale 1% and 2% precision resistors; in place of all 5% resistors
- Texas Instruments op-amps; for the hell of it
- CTS volume pots
- Bournes trimmer pots; for crossover adjustment
- 16 gauge polarized AC power cables; non grounding
- gold plated female RCA inputs
- new fuses inside and out
- Cardas Quad Eutectic solder

Now, down to business. With the help from Ken Kreisel himself, who offered up the schematics, manuals and any other questions that might need answering (Thanks Ken!), I warmed up the Pace soldering station and prepared for battle.

First, I removed the plate amps and power supplies from each speaker, then disassembled one. On the first amp, I removed all the old parts that were to be replaced by new, leaving one amp together as a visual aid. Each board was scrubbed with a dry old toothbrush and sprayed off with DeoxIT D5 before the new parts were installed, along with all eletronic connections. I had a local tech and AK member DanO55 test the STK power amp modules for me, to make sure they were good, which they were (Thanks Dan!).














Next up was to replace the the RCA inputs, gain pots and power cables. (and clean the dust of those plates!)

Part 1 - continued

After that, I replaced the power supply caps for both, since they wouldn't take much time.










Then on to the main event, populating the amp PCB with new parts and soldering them into place. Here's one done, next to one with old parts still on...



...and finished boards.






Finally, joining the PCB's, amp modules and plates back together.

Part 1 - conclusion

Finished plate amps and power supplies, awaiting installation back into their enclosures. :thmbsp:




Old parts.




Electronics installed...speakers ready for testing (in which they passed with flying colors!).





Stay tuned for Part 2 - monitor crossover: new caps & resistors. Planning to tackle that in the upcoming weeks.

Now, time to get sucked back into the music... :beer:

Wowza - Very nice

Those look great. I never knew they made a tower like that.

Very nice, wish I had a chance to hear them before I left. Great reason to come for a visit.

Just curious... what r those surround speakers in the pic backround?

rotelrx503 said:

Just curious... what r those surround speakers in the pic backround?

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Those are Canton speakers...the 5.1 setup is called the 'Movie 150 QX'.

I bet they sound so dern good.

Speakerbox said:

I bet they sound so dern good.

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They really do, I'm impressed.

I've had some very nice speakers come through my domain and I have to say that these are up there with the best of them. I wish I hadn't put this project off for so long now. They're keepers. :yes:

what's the reason for the large foams?

Sonance'84 said:

They really do, I'm impressed.

I've had some very nice speakers come through my domain and I have to say that these are up there with the best of them. I wish I hadn't put this project off for so long now. They're keepers. :yes:

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Those are pretty cool, I have a set of Satellite 1 speakers with the sealed odd shaped Subs. I use them in a secondary system with Rotel preamp and power amp. I wouldn't mind a pair of those towers.

Speakerbox said:

what's the reason for the large foams?

Click to expand...

I'm guessing they're some sort of diffraction tool. I've seen foam, felt and other materials used around tweeters and midrange drivers in many different ways, by many different companies.

On this speaker, the tweeter is flush mount with the cab, but the mid and woofer stick out about 2 inches or more and the foam is flush with them both.

I'm just as impressed with this cabinet design as I am with how great they sound. Honestly, the cabinet is what drew me to them in the first place...I knew they were designed this way for a reason and not just for aesthetics. Some serious time went into these.

13x24mancave said:

Those are pretty cool, I have a set of Satellite 1 speakers with the sealed odd shaped Subs. I use them in a secondary system with Rotel preamp and power amp. I wouldn't mind a pair of those towers.

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Right on! I love the look of those S-1's, especially if they have the wood veneer on the front baffle. The Peerless tweeters our speaker share are amazing...I wish I had two per tower!

I was using just the S-2B monitors by themselves for about 6 months while the Volkswoofers were out of the cabinets, but I supplemented the low frequencies with my home theater M&K MX-90. The sub was off to the side of the towers and pushed back a bit, I just left it where I had it setup for 5.1 surround. The combo sounded good and the monitors sounded promising...but nothing like the sound I'm now getting from the SV-200B's as a whole. I wasn't expecting the midrange to become so fleshed out and the width & depth of the soundstage to open up like it did. I think a lot of that has to do with the 12" woofers being on the same baffle as the monitors. Whatever the case may be, these speakers image like crazy now.

Wow wow wow!

I wonder if those towers play as loud as Sat1, I bet they do but I'm always surprised are how loud and full my set plays when asked to. My set has the black baffles.

13x24mancave said:

I wonder if those towers play as loud as Sat1, I bet they do but I'm always surprised are how loud and full my set plays when asked to. My set has the black baffles.

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I haven't heard the Sat-1's, but I'm guessing the S-2B's play just as loud. The only difference is the cabinets & mid drivers. I'm pretty sure they have the exact same specs...and I know the crossover is the same too, except my S-2B's have a handful more resistors.

I barely have to turn my amp up now that the speakers are working as a whole, but when called upon, they can be cranked up with no distortion.

Great work. I am glad to see you get these working.

Tony

Update

Just received my package of new capacitors and resistors for the monitor crossovers! Can't wait to get started, not sure when I'll have time this weekend though.

Parts include Mundorf E-Cap AC "plain" electrolytic caps, Vishay MKP-1837 bypass caps and Mundorf MOX non-inductive resistors.

Those are beautiful!

Great work on the crossovers as well! You'll enjoy them for years to come!

Glenn

Restoration: Miller & Kreisel Sound (M&K) SV-200B tower loudspeakers, cont'd

> Part 2 - monitor crossover rebuild <

I've been absolutely in love with these speakers since I got them working again as a whole back in November 2014. They sounded amazing, even with the 33 year old electrolytic caps in the upper section, the 2-way studio monitor (S-2B). I really couldn't get over how good they sounded with the lower octaves filled out by the Volkswoofer V-2B's. Listened to a lot of my favorite recordings over again and got a really good grasp on what these speakers could do.

Now, for the past 2 days I've been working on swapping in those new parts from the previous post into these crossovers. It was quite a challenge, as you can see there is virtually no room on the board for larger film caps. I went with Mundorf E-Cap "plain", which are slightly larger than their "raw" version of this NP electrolytic cap. While the "plain" are much larger than the original T.I. caps, they're still much smaller than most film caps of any significance, allowing me to fit them in with a little creativity. Two of the caps had to be paralleled to meet the required values. All caps were then bypassed with Vishay MKP 1837 film caps of 0.01uF. The Mundorf MOX resistors fit better than the original sand cast ones, so that helped a little. I did have to wire a pair in series to get a required value, which was a first for me, but no biggie. Also, the rotary knobs got a good cleaning with DeoxIt while I was in there. Oh, and RTV was used to secure caps together and to the board, so they don't vibrate around.

I had my work cut out for me with these, but it paid off when all said and done. I did the best I could with the space provided and nobody will see them anyways, except you guys! Check my post above to see the crossover with the stocks parts in for comparison.

Parts removed from one crossover...



Old parts next to their replacements, for size comparison...



and the completed crossover.