MCS 3245 q-u-e-s-t-i-o-n-s-?

I'm watching an MCS 3245 on shopgoodwill, locally. What is a decent price to pick one of these up?

I personally wouldn't go overboard, especially if it's never been recapped. Also, if it drops a channel, it'll probably be a sticky pot, lever, or button. The level meters can be problematic too. I've yet to hear a 3253 or 3275, so it might be a step down from your 3253. I need to double-check between mine, but I *think* the 3245 has a flatter/compressed "2D" stereo effect vs. a 3233 which sounds more dynamic while the 3245 seems to have a quieter noise floor though. I will say though at lower volume (like between 1 and 5 watts roughly) on both 100% stock 3233 and 3245, where I had one amp running a left channel and other amp running a right channel, both getting the same signal, and powering identical cabs with tone defeat on, I couldn't tell which was which. Not until higher volume with tone boards on did it become more distinct. I will say the 3245 doesn't seem to appear as much as other units, so a fully cherry unit might be harder to come by.


@Hifirob2 How did you get the FCC ID number listings? When I was looking several years ago, I had no luck with them, and mostly only able to find current listings of modern stuff. Also, do you have a list of what was Arvin, what's Capetronic, etc.?
 
Capetronic. Very interesting. Also wasn't aware of them. The 3233 is a very basic preamp, tone control, and power amp compared to the 3245 or above. It only uses resistors in the constant current sources which has far more noise, distortion, and slower slew rate than a pair of diodes or another transistor setting the voltage. I have studied amp design and seen back to back comparisons which show exactly how different current sources effect noise, distortion, and harmonics. Resistors are not the way to go, although in certain cases could add some even order harmonics which some people seem to prefer. Even order harmonics are what give tube amps their "warm" sound. Most amps inherently have odd harmonics do to tripling circuits in power amps.
 
@Hifirob2 How did you get the FCC ID number listings? When I was looking several years ago, I had no luck with them, and mostly only able to find current listings of modern stuff. Also, do you have a list of what was Arvin, what's Capetronic, etc.?

I just was looking at ebay listings for MCS (because I have no life), and I saw the 3228 listing with Technics plastered all over it. I looked at the photos of the rear, and there was the FCC number. A few MCS pieces have that, but you don't see it often. Capetronic is ANV9UD, and NEC is A3D9MD. I'm not sure what Arvin's number is. Also, most all NEC made gear sold in the US will have a "720" on the back near the box with all the rest of the info. Sometimes the 720 is followed by one or two random letters, but the 720 tells you it came out of NEC's Tokyo, Japan factory.

I don't have a list of what's what, but from what I can tell, nearly all of the Taiwan stuff from 1977 thru at least 1986 was one or the other - with most being Capetronic (from the code on the service manuals). This includes receivers, cassette and 8-track decks, and other pieces from Penney's that wasn't MCS - like some of the all-in-ones. Sears also used Arvin a lot. If the Sears model number starts with 132, it is from Arvin.

I know both Arvin & Capetronic were capable of making high quality stuff, so I can't say which was better. That so many pieces from either maker are still working all these years later speaks to their quality. But put on a pair of good headphones, and do some critical listening, and I prefer the NEC made pieces by a wide margin. Most of the Taiwan models seemed to have noise or hiss in the backround that bothers me.
 
@Hifirob2 It's a 3228? Tried looking and can't find any listings or any info.

Yeah, the 3233 (out of 3 I've had) all had the hiss and some noise when no audio was present that gets affected by where the tone pots are set and if the filters are used. Need to take the 3245 out of storage to confirm, but don't remember it being nearly as noisy. Cut teeth on a 3233 so the hiss isn't as bothersome.

@Racingh11 That's interesting you mention the slew rate. I've noticed some amplifiers "respond" very quickly to sounds, while other do no not. So that's the "slew rate" then? Can the slew rate (speaking in general, no amp specifically) be altered with tighter, modern resistors?

Maybe due to something I changed, by the 3233 I use on and off seems to respond fairly quickly. Quicker than either Realistic unit 2280/2600 I own, and almost as fast as the 3125 (though the 3125 has a better overall clarity). And for whatever reason, it sounds really expansive vs. other amps in my sig when using the same speakers/headphones. Granted, every film/electrolytic on tone, amp boards was touched and is has super through main caps, and is noisy @idle, but when playing something like rock music on speakers or modern recordings/shows via the PC through a dac, it projects the sound out the speakers as if the cabs grew a couple a feet in height and the stereo effect is very pronounced. Lots of depth, especially in the sweet spot.
 
Billy Dio - Under "vintage stereo receivers", the description in the title is:

"MCS Modular Component Systems 693-3228 Vintage Stereo Receiver Tested (Technics)"

*should be 683-3228, but oh well.....(no affiliation)

The 3228 was a late 1982 model, but doesn't appear in any of my MCS catalogs. A lot of the lower end models came and went quietly. I don't remember ever seeing it on the store shelves back in the day. Maybe it was available through the catalog dept.?
 
OK, found it. They were definitely trying to compete with the look of the Technics units of the time with the slim silver case and sliding controls. My mom had a silver Technics SA-110 (20wpc) from around the same year, and they used those 1/4 twist terminals on the back and completely different tuning wheel. That 3228 looks like it's a low-end NEC or something.
 
There is a formula to figure out what the slew rate needs to be to keep up with a certain frequency at a certain voltage. Most good amps will exceed required specs by a good margin, but could be what plagues the less expensive models. Transinternodulation (TIM) is also a good indication of whether an amp has good sonic ability. It uses a different set of signals than THD or IM distortion tests. Soundcraftsmen put a lot of emphasis on that since their amps had little or unmeasurable TIM. Soundcraftsmen also has slew rates greater than 50v/uS stereo or 100v/uS bridged, it far exceeds required slew to achieve high frequency at full output. Most amps are much less than 50v/uS. As far as modification goes, the 3233 or 3235 could be upgraded by calculating what voltage the resistors set the base of the constant current transistors to and subtract .6v and divide that voltage by the emitter resistor value to find the current of the constant current source. Then replace the base to emitter resistor with a pair of diodes in series and divide .6v by the circuit amperage found in previous step and that should give you the resistance of the new emitter resistor and replace that. The purpose of this is the diodes always keep the base-emitter voltage the same and therefore the current steady, even if rail voltage fluctuates. Resistors setting the base voltage fluctuate with changing supply voltage and let current changes and noise in the circuit as well as slowing things down.

Update: This modification will not work on a 3233 or 3235 as noted in later post, but will work on a 3230 constant current sources Q219 and Q220.
 
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Differential stage voltage matters too. I don't remember the technical term for it, but I think of it as "voltage resolution". Where you want the voltage swing to be as much as possible so every detail in the music makes considerable change in the signal at a given current. Also keeps it farther above the noise floor and improves the S/N ratio. Soundcraftsmen class H amps actually run the diff stage at +/-91v even when the power rails are running at +/-63v. At higher output it all runs off the +/-93v rails. This gives the amp high clarity and slew rate. Many of the MCS units regulate the differential stage at 12v even if the output stage has 33 or 38v. So in essence, one covers a much larger range and has a greater voltage resolution or capability for sonic detail than the other.
 
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There is a formula to figure out what the slew rate needs to be to keep up with a certain frequency at a certain voltage. Most good amps will exceed required specs by a good margin, but could be what plagues the less expensive models. Transinternodulation (TIM) is also a good indication of whether an amp has good sonic ability. It uses a different set of signals than THD or IM distortion tests. Soundcraftsmen put a lot of emphasis on that since their amps had little or unmeasurable TIM. Soundcraftsmen also has slew rates greater than 50v/uS stereo or 100v/uS bridged, it far exceeds required slew to achieve high frequency at full output. Most amps are much less than 50v/uS. As far as modification goes, the 3233 or 3235 could be upgraded by calculating what voltage the resistors set the base of the constant current transistors to and subtract .6v and divide that voltage by the emitter resistor value to find the current of the constant current source. Then replace the base to emitter resistor with a pair of diodes in series and divide .6v by the circuit amperage found in previous step and that should give you the resistance of the new emitter resistor and replace that. The purpose of this is the diodes always keep the base-emitter voltage the same and therefore the current steady, even if rail voltage fluctuates. Resistors setting the base voltage fluctuate with changing supply voltage and let current changes and noise in the circuit as well as slowing things down.
OK, I just looked at the schematics for the 3233 and it's not quite as simple to mod as I thought. I hadn't noticed before, but it appears that this amp doesn't have a constant current source(for voltage stage, uses zener for current in differential stage) and relies on resistor and other transistors set by resistance to set voltage amp stage current. You would almost have to add a transistor for constant current source to the circuits where resistors R515 and R516 are. A resistor may also have to be added to the emitter of Q505,Q506. The way it is now as voltage increases, amperage increases through R515,R516 losing voltage that could power the driver stage. But the interesting thing is caps C508,C509 that feed output to the back side of R515,R516 and increase the voltage seen at the drivers. Maybe this is why @Billy Dio says it comes alive?... It is like some positive local feedback loop to the voltage stage to increase slew rate and a negative feedback loop to the differential stage to keep distortion in check. Very cool for a simple 8 transistor amp!
 
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Now I like these 3233 and 3235 models even more. It makes me wonder how good you can get one to sound. As far as resistors that Billy Dio mentioned, tighter tolerance probably wouldn't make much of a difference. But using metal film resistors for lower noise on an amp that really relies on resistors to control things, might make an improvement. And of course the best capacitors available which he said he replaced already. Maybe even use metal film caps for some of the electrolytics. Possibly find new transistors with lower noise and better performance figures. Possibly build a constant current source to replace the 12v zener and 12k resistor that feeds the differential stage tails or increase differential voltage to 20v zener and 20k resistor. And have one for each channel for better stereo separation. Or increase capacitor C516 on the current setup
 
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I gotta say, I really like hearing opinions from other MCS experts. The models I prefer are all from Japan (NEC made), BUT.....I have a 3222 that impresses the hell out of me. It's pretty much mint and has very low hours on - but it is a very well designed receiver that sounds way better than it should. It was from the very first generation of MCS gear (early 1977). I had a 1979 MCS 3212 in college that never (ever) let me down. It was replaced by a 3246 (NEC made) a few years later, and it was light-years better than the 3212.

I had a 3233 for a short time in 2008, and was not impressed with it. Sold it pronto. I have two 3245s that just sit (looking pretty). The 3222 gets used a lot through headphones. I had a 3260 that was a very good performer. Cheesy plastic switch covers and all. I sold it - no WOW factor. I have two 3253s that I'll never part with. So darn good for what they are. I have no desire for a 3275. The tuner and phono preamp in the 3275 are identical to the 3253, and the amp section is easily bested by the similar design in the MCS 3865 (in dual mono configuration). The 3125 is in a class all it's own - it has no right sounding so good - and I keep the EQ bypassed.

A lot of this comes down to Taiwan made units VS. Japan made units. A current ebay listing for a MCS 3228 got me digging again on Google, because the listing is adamant that Technics made it (and most MCS stuff). That angered me, because I know it isn't correct. Why mention it? Because this receiver was made in Taiwan, and lists it's FCC ID# on the back. A quick search reveals the true manufacturer as "Capetronic". I have been wanting to find this bit of info. out for years. I know that Arvin (ARV) made some of the Taiwan units - but not all. MCS service manuals list the manufacturer as a three letter code, and now all the "CPT" coded ones are answered. The MCS service manuals that list "ITO" as the manufacturer code are all really NEC products - not rebadges, but built by NEC to Penney's specs (like the 3845 integrated amp and 3125 receiver). That may be where the confusion of ITOH Radio making some MCS pieces comes into play. ITOH was probably used as a middle man for documentation of some models - but were not the actual manufacturer. Digging through my files, it seems Capetronic made a LOT of these Taiwan units - similar markings on the rear panel and the same serial number sticker and numbering sequences.
I just realized what it was that you said there. So now I'm back to thinking the Arvin units are just the Taiwan units with the red and black push button speaker terminals and the other Taiwan units with different back-board and screw terminals are something else which could be Capetronic? I thought they were different and then after the Arvin info, thought maybe the screw terminal models were earlier models before they made them a little fancier...
 
Perhaps we should request an MCS forum and start laying out what is known about the brand and each model in a more organized fashion.
 
I just realized what it was that you said there. So now I'm back to thinking the Arvin units are just the Taiwan units with the red and black push button speaker terminals and the other Taiwan units with different back-board and screw terminals are something else which could be Capetronic? I thought they were different and then after the Arvin info, thought maybe the screw terminal models were earlier models before they made them a little fancier...

There were so many models coming out in the late 70s, that going by the speaker jacks to determine the manufacturer, may not work all the time. Your best bet is to find the service manual and get the three letter code near the upper right hand corner. That will be the best way to get an accurate answer.

For example, the MCS 3230 was from Arvin. The 3227 was from Capetronic and was 25 wpc. The 3228 mentioned above was also Capetronic - but the SM states it is only 5 wpc (at 10% THD) and only weighs 10 lbs. That would make it the lowest powered MCS receiver that I've come across.

The 3330 and 3331 8-track decks were Capetronic, and judging by their design, I'd venture that most of the 1st and 2nd generation MCS units (from Taiwan) were from Capetronic - including my old 3212, my current 3222 and 3550, and even the 3233. Lots of similarities inside and out. I would need to see the SM for the 3233 and 3245 to be certain.
 
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There were only 5 models that used those particular speaker terminals; the 3207, 3230, 3233, 3235, 3245. Considering I never saw any other brand that uses those terminals, the 3233 and 3235 are the same but run at 33v vs 38v, and the 3235 shares a tuner lens and design styling with the 3245, The 3207 has a rear panel like the 3230 and the same push buttons on the front as the 3235 and 3245. I'd say it's safe to say they were all made by the same company.
 
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@Hifirob2 , I do not have any FCC numbers on the two I have sitting out at the moment, but do you know anything about the "code no." stickers on the back? I have a 3245-10 with a code sticker C912 and a 3233-20 with C807 on it right next to the service model number sticker.
 
I also just noticed the 3233 and 3245 have the same UL listing number of 459E and the 3230 is 652G if that means anything. Also just ordered the OEM service manual photocopy. So we shall know who made it soon enough. :)
 
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@Hifirob2 , I do not have any FCC numbers on the two I have sitting out at the moment, but do you know anything about the "code no." stickers on the back? I have a 3245-10 with a code sticker C912 and a 3233-20 with C807 on it right next to the service model number sticker.

Those are the date code - when it was manufactured. The 3245-10 (version two) was made December of 1979, and the 3233-20 (version three) was made in July of 1978.

I just found a picture of the front page of the SM for the 3207. There is ink covering part of the code, but it looks to me to be Arvin. So that fits with the others - since the 3207 (13.5 wpc) is the spitting image of the 3230 - but uses different speaker jacks (ugh). The 3223 was Capetronic, so that lines up with them using those screw terminals on early models. My JCPenney 3012 & 3112 receivers (not MCS branded) use the screw terminals and were Capetronic made, according to the SM.

Without the FCC codes, the SM will answer these questions.
 
Thanks Rob, and you're right the speaker jacks are different, although still push style and no screws. I have to say this has been fun trying to figure out the history of this company with everyone. It reminds me of classic car culture, except fewer people participating and fewer resources available. Would be nice if there was a magazine dedicated to classic gear and featured company history, reviews, repair articles, write-ups on reader's stereo of the month, etc. I'm really not into the current publications of super elite priced stereos or all the techy stuff with mp3, bluetooth, and processors.
 
I haven't been able to find any service manuals for MCS stuff that wasn't a direct clone of an NEC item.
 
I haven't been able to find any service manuals for MCS stuff that wasn't a direct clone of an NEC item.
The only direct NEC clones are the 3249 and 3260. You can find info for MCS stereos in old Sams Photofact manuals for sale on ebay or other sites, or you can order scanned prints or downloads of Photofacts or OEM manuals here, https://www.samswebsite.com/ . I usually use that website to find which manual the info is in and try to find an original somewhere before I order a reprint. They usually come to $35, so they are not cheap. Original manuals can often be found for $20. If anyone wants a copy of the 3233, let me know. I bought the 3233-00 and 3233-10 and I cannot find a difference between the two.
 
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