Sanyo dcx3000k - anyone familiar with?

[jdmack]

I picked up a Sanyo dcx3000k today because it was only $15.00, and one of the settings was "SQ Logic." If it had just said "SQ," then I probably would have passed.

Anyway, the thing powers up, and it will pass through a 2-channel phono signal, but that's it. There are two 4-channel outputs - "Playback" and "Record." Neither of the playback outputs work, and only the fronts of the record outputs work. And the front signal doesn't change no matter if the amp is set to "SQ Logic," "Matrix" or "2 Channel." So, should I...

A. Toss it in a landfill?
B. Take it to a thrift Store?
C. Perform an easy fix offered by someone who has one of these and knows what the problem is?

J. D.

 

[Richo]

Hi there jdmack,

I picked up a sanyo dcx3100k (almost identical looking) a few weeks back fairly cheap from feebay. So far I'm fairly impressed with the matrix setting on the decoder and using stereo source for decoding. I'm hearing solid rear separation on certain tracks which leads me to beleive its at least a 1/2 logic decoder.

My best guess for chrono is that the amp dates from 75 or 76.

Have a look on the back of the amp for a 2 channel or 4 channel selector switch. Mine would not put out on 4 channels until the switch was thrown. Seems to kick in separate circuit boards for the 4 channel stuff.

cheers, Richo.

 

[watsontr]

Howdy Richo and all...
Although Sanyo doesn't seem to be a brand beloved by Quadraphiles, I've had a DCX-3100K since June 1977 and I've always thought it was pretty cool and has also provided sterling service. I also have a DCX-6100K that I use as my main system in conjunction with a few RTRs (Sansui, Otari, AKAI, Teac), a Technics RS B505 cassette deck and a Zensonic Z340. The Zensonic is locally badged MT1389 DVD player with DTS encoding to its own analogue outputs. I use this to play DTS encoded quad recordings. Still looking for a Q8 though!

Hi there jdmack,
Have a look on the back of the amp for a 2 channel or 4 channel selector switch. Mine would not put out on 4 channels until the switch was thrown. Seems to kick in separate circuit boards for the 4 channel stuff.
cheers, Richo.

From memory this is the switch that will series-up the two each of the four amps for stereo for increased output power. Best not switched when the amp is switched on I'd imagine! Enjoy the quad
Regards
Tom

 

[Richo]

watsontr: thankyou for sharing that info ! You are the only person I've managed to find that knows anything at all about the sanyo units. I am completely at a loss to find any documentation whatsoever on either my 3100k or anything in the sanyo line from the same era. Sanyo themselves don't want to know about it (I gave up after 4 emails).

I'm afraid I have many questions for you !

Would you have any specs / info / pix / etc you could share ? I was unaware sanyo made anything bugger than the 3500k. I am quite intrigued by the 6100k you have... was that one the TOTL for the sanyo quad receivers of the day ?

I'm looking for another receiver with more balls for my main system, would like to use my 3100k in a smaller room. The 3100 is fine for normal listening levels but seriously runs out of puff when you turn the wick right up to "everyone's gone out and I've got the house to myself" levels ! (I have 4 x big 80's 3-way floorstander speakers to keep honest)


I'd also like to pick your thoughts on the decoders, especially the matrix setting. How do they compare with the more popular quad decoders for separation from stereo?

Does the SQ setting on your 3100k do much for rear channel separation? (mine doesn't seem to have a patch on the matrix setting for stereo source decoding)

Does the 3100k require a separate CD4 demodulator or have one built in?

Cheers mate,

Richo.

p.s. are you on the nsw east coast ?

 

[watsontr]

Would you have any specs / info / pix / etc you could share ? I was unaware sanyo made anything bugger than the 3500k. I am quite intrigued by the 6100k you have... was that one the TOTL for the sanyo quad receivers of the day ?

If you go to

http://users.tpg.com.au/watsontr/Sanyo/

I've added a couple of pages from the user manual. Pretty simple stuff but it tells you that you need a demodulator and that is what they expect you will use in the Aux input. I'm not sure what specs are available but I'll have a look. I am hoping to get one of those fancy new demodulators so I can then try out some of those CD-4s that I have too! I have a JVC 4dd-10 but that just makes a horrible noise.

The 6100 is I expect was possibly their TOTL or approaching it for the time. I don't have any specs on it. I bought it off ebay a few years ago as a complete functioning unit including speakers for $50. I do recall seeing something bigger but can't recall the details. It looks more like a furniture piece with the receiver/turntable built in to a similar sized enclosure as the main speakers. The surround speakers are somewhat smaller. The 3100 came as a stereo unit capable of being quad. The surround speakers were additional/optional. Also some units came with an Apan turntable instead of the standard Sanyo. I know mine had the Apan whereas my sister's had a Sanyo.

I'm looking for another receiver with more balls for my main system, would like to use my 3100k in a smaller room.

Thanks for the offer but I already have two of them plus a Technics, JVC and a Sharp. I'd probably want it still if you find that you have no use for it. So long as my wife's not listening that is!

I'd also like to pick your thoughts on the decoders, especially the matrix setting. How do they compare with the more popular quad decoders for separation from stereo?

I can't really help you much here mate as I've not had much in the way of alternates to compare. I expect that the 3100 and the 6100 would sound similar and that's what I use mostly. The 6100 does have an additional mode RM. I expect that the 2-2-4 is the same as the Matrix setting on the 3100 and the RM is a no name QS. I think it sounds pretty good though probably not to the level of the Sansuis and Tates I hear so much about on this list though I've never sighted one. That said, my quad vinyl sounds damn fine to me and things like the Tubular Bells box set CDs seem to decode OK.

p.s. are you on the nsw east coast ?

Yep. Probably about an hour south of you
Tom

 

[watsontr]

Richo
If you are interested there are a couple of photos at:

http://users.tpg.com.au/watsontr/Sanyo/01.JPG and
http://users.tpg.com.au/watsontr/Sanyo/02.JPG

that should give you some idea of what a 6100 looks like. Photos are a bit dodgy. I tried to find the SLR in my daughters room but that seems like a lost cause!
Regards
Tom

 

[Richo]

Tom, sorry for the confusion regarding my 3100, I meant that I was going to use it in another room after I find something with more oomph.

The user manual you uploaded was most welcome, thanks mate!

The pix of the 6100 surprised me a bit (thanks for them), I was expecting it to look more like the 3500. I think the individual level sliders are better than the rotary pots found on the 3XXX series too, you can see just where they're at with a quick glance from across the room, Nice!

Also interesting that there is an extra decoding option on the bigger brother. Which setting do you find works best on a stereo source?

An hour south of me ! Wow.. its a small world. I'm in Mt. Hutton, just south of charlestown.

What are the decoders like in your other amps? I read that sansui had an open book for matrix reference design available to any other manufacturer who wanted it as part of their push for QS supremacy. Really makes me wonder if there's some totally unknown gems out there with full logic variomatrix reference boards in them!

I also believe my 3100k has no blend resistors (or IC equivalent) in its circuitry. There are some tracks that will output to the front speakers only in parts of the one song, flick to 4 channel output in other parts and then to discrete voicing from the rears. When I find a higher wattage replacement I'm definitely pulling down the sanyo for a real good look inside at the boards / components. I reckon she's a real sleeper in the decoder dept but alas I have nothing to compare it too, only what I read on the net about others experience.

Cheers, Richo

 

[Led9]

I used a 3100K for a while before I got my Sansui. As I recall it didn't handle some CD sources very well. I would get a mild distortion even at low levels from certain CD's. Never a problem with vinyl LP's though. Don't know if this was just a problem with mine or if all are prone to that.

Rick

 

[watsontr]

The user manual you uploaded was most welcome, thanks mate!

Glad to be of assistance

I think the individual level sliders are better than the rotary pots found on the 3XXX series too, you can see just where they're at with a quick glance from across the room, Nice!

I think I prefer the 'master' volume control of the 3100 most of the time. I find the sliders a little fiddly at times. Could do with a service I expect

What are the decoders like in your other amps? I read that sansui had an open book for matrix reference design available to any other manufacturer who wanted it as part of their push for QS supremacy. Really makes me wonder if there's some totally unknown gems out there with full logic variomatrix reference boards in them!

It's been a while since I've tried them and they are stored at present so I can't really comment.

I also believe my 3100k has no blend resistors (or IC equivalent) in its circuitry. There are some tracks that will output to the front speakers only in parts of the one song, flick to 4 channel output in other parts and then to discrete voicing from the rears. When I find a higher wattage replacement I'm definitely pulling down the sanyo for a real good look inside at the boards / components. I reckon she's a real sleeper in the decoder dept but alas I have nothing to compare it too, only what I read on the net about others experience.

I'm pretty certain that I have the scan of the schematic at home so I'll check it out tonight
Regards
Tom

 

[Doug G.]

I used a 3100K for a while before I got my Sansui. As I recall it didn't handle some CD sources very well. I would get a mild distortion even at low levels from certain CD's. Never a problem with vinyl LP's though. Don't know if this was just a problem with mine or if all are prone to that.

Rick

Hey guys, thanks for an interesting thread.

Rick, the distortion you heard may just be overload distortion. It's a sign of this if, as you say, the distortion is there even at low levels.

This is caused by the CD player outputting more signal than the amp. input can handle. CD players typically put out 2 volts and many older amps were not designed to take this much where the peaks may go higher than the max. allowed.

Hey, do you Aussie guys pronounce "solder" like we do in the States as "sodder" or like in Britain as "soul-der"? Hehe, just curious. Years ago where I worked, we had some instructional videos about how to solder and they were produced in London. We got a big kick out of their pronunciation.

Talk about easily amused huh?

Doug

 

[watsontr]

This is caused by the CD player outputting more signal than the amp. input can handle. CD players typically put out 2 volts and many older amps were not designed to take this much where the peaks may go higher than the max. allowed.

I had been thinking along the same lines myself. I do recall when CDs were first introduced there seemed to be a low level scare campaign alerting people that "high output" CD devices may harm their systems. I expect that this was agreed upon by all manufacturers of stereo equipment but I thought CDs sounded OK to me when connected to the Aux input of my amp. Never noticed the distortion, even though it was a 3100K, but I may have spent too much time standing in front of a couple of Marshalls amps.

Hey, do you Aussie guys pronounce "solder" like we do in the States as "sodder" or like in Britain as "soul-der"? Hehe, just curious.

Is this like very english Colin in the movie Love Actually when he meets the American girls in a bar? Hey Doug, can't you Americans see the 'L' in soLder or did you change the spelling of that too?
Tom in Australia, also easily amused

 

[Richo]

Tom: thanks mate, your thoughts and data have been invaluable to me !


Led9: Doug G is right! A quick fix would be to run an Eq between your cd source and the amp, knock a couple of dB's off the master gain / level control, works well, I just tried it out on my system. Its just a basic signal clipping problem with the first amp stage inputs. It should have no ill effects on your amp to run it into clipping either so don't worry. I know that sounds a bit radical but guitar amps run with massive amounts of clipping early in the signal chain to acheive distortion sounds. They also live for decades whilst doing it. Same basic electronic componentry.


Doug G : You are totally correct regarding input overload. I easily replicated the mild distortion just by adding 4dB of eq gain to my digial aux in (PC sound card) on the 3100k. Aussies pronounce solder "soul-der" ... man I had no idea you guys said it "sodder" ... that cracks me up ! Almost makes it sound like a cuss word... "SODDER!!"


I'm with Tom... also easily amused, also an Aussie !


Cheers, Richo.

 

[watsontr]

Aussies pronounce solder "soul-der" ... man I had no idea you guys said it "sodder" ... that cracks me up ! Almost makes it sound like a cuss word... "SODDER!!"

Same here! I am sure a deed by that name would have been illegal at the Catholic school I went to! Got a great snicker out of this reading at work today so thanks again Doug

Richo
The schematic I have of the 3100 is at

http://users.tpg.com.au/watsontr/Sanyo/Sanyo schematic.jpg

It's not in colour but it has that essential 70s flavour about it
Hope it helps
Regards
Tom

 

[Richo]

Oh thats just brilliant... thanks Tom, you rock!

I'll take it to work and output it on the A3 printer when I can, should be real easy to have a good look at it then.

 

[Doug G.]

Oh no! I completely forgot that "sod" is a cuss word! LOL! Oh, sod the abattoir!

I know, the "L" is silent! Ya that's it! On the east coast here it's pronounced "sodda".

Anyway, I ran into the overload distortion on my setup (all Heathkit amps with external decoders/demodulators and Advent stacks in all four corners) when I had my Technics CD changer (my son has it now and I just use the DVD player for CDs). There was just this slight irritating sound like record wear particularly in the back speakers. I finally discovered that if I turned down the input pots on the main amp into which the CD player was feeding, it eliminated the distortion.

EDIT: I forgot, Richo is correct about the overload not normally dangerous to the input circuitry. It COULD be if it were a gross overload like 100 volts er sumpthin' but a few millivolts over won't normally do anything but sound distorted.

G'day, :^)
Doug

 

[Richo]

Haha @ Doug G ... thats the spirit! G'day is a national / universal greeting here


I too noticed the rear speaker distortion as the very first sign of clipping, especially in the higher frequency's. I wonder if as part of the decoding process the gain stage for the rear speakers is very slightly hotter then for the fronts or whether specific higher frequency bands are aggressively boosted for rear channel separation ? Interesting.

Your heathkit setup sounds awesome, are they tube amps?

Cheers, Richo.

 

[Doug G.]

My Heathkits are all the -29 series solid state amps (mainly because I built an AA-29 in March of '76) in various forms which were produced from about 1970 - 77. To me, they sound great! They're about 50 watts/channel. Each pair of Advents has its own amp.

I have 2 demodulators, A Technics SH-400 and a Panasonic SE-405. The SQ/QS decoder is a Sony SQD-2050 which sounds good to me. Plenty enough separation for a real quad experience.

I just realized that maybe I should have explained the "sod the abattoir" remark as being a Monty Python reference from the "Architect Sketch" as everybody might not know what the heck it meant and thought I was nuts or barmy or something and maybe I am but I think that's OK, right? :^)

Doug

 

[Richo]

Doug: I just scored a very interesting demod myself, its a rebadged jvc 4dd-5 (sharp optonica). Its not here yet but I'm keen to give it a whirl! Can you tell me a little about getting the most from your CD4 setup ? I know I'm going to need an elliptical needle and a good cart for starters and some kind of setup test record to configure the demod with. Is there a consensus on which test record is better ?

Your sony 2050 intrigues me... does yours suffer the dreaded "pumping" sound so many espouse or is that a myth or able to be tuned out ?

Monty python rock!


Tom: mate I looked over the schematic you posted and as far as I can tell all the decoder boards are not on it. There must be a supplementary diagram somewhere with outboard boards "a" through "d" on it somewhere. Now I am really intrigued.....

On the plus side:
- the 4 separate amp sections are clearly visible.
- the FM has 3 tuning gangs, AM has the obligatory 2, nothing special there but nothing crapola either.
- has world voltage, 120v - 240v
- the din plug on the back is for what looks like a stereo tape loop
- the 4 channel headphone amp looks quite exotic..

Now I'm really keen to pull the sanyo apart at the first available opportunity. Why would the demod board info not be on the schematic? ... hmmmmmmm?

Richo.

 

[jdmack]

Hi there jdmack,

I picked up a sanyo dcx3100k (almost identical looking)

<snip>

Have a look on the back of the amp for a 2 channel or 4 channel selector switch. Mine would not put out on 4 channels until the switch was thrown. Seems to kick in separate circuit boards for the 4 channel stuff.

I looked at the back of mine and did not find a 2 channel / 4 channel selector switch. So at least that much is different between the 3000 and the 3100.

J. D.

 

[Doug G.]

First, I want to apologize to J.D. for getting this thread off on a tangent (oh well, at least it stayed quad, right?)

Richo, to answer your questions:

I'm sure you meant to say that you will need a Shibata or similar stylus, not elliptical. Actually though, it really wouldn't matter what shape the stylus is as long as the response of the cartridge, as a whole, goes up to 45 -50 kHz. That's the most important spec. The response MUST be there to retrieve all of the modulated carriers. Also, the separation has to remain good up there too.

The rebadged JVC 4DD5 should be a good one if it's in good shape. Although you can adjust a CD-4 system without a set-up record, it is much easier to do it with one. I personally like the Harmon-Kardon record (it's the one with a black border on the cover with a large white square in the middle and small multi-colored squares within that) because there are vocal announcements right on the record to indicate what the following tone is for. Very easy and quick. Just adjust those back channels for minimum output with the correct signal.

I really like the SQD-2050 and don't hear any pumping at all. Very nice fidelity and separation.

The only thing with these (I have 2) is that Sony used a double sided board for the main one and there are places where the two sides are connected electrically through holes with hollow pins in them and soddered ( :^)) on each side. The soldering wasn't the greatest (or the pins used didn't have the best solderability) and, through time, these connections become intermittant resulting in channels cutting out and noise. I fixed both of mine just by resoldering this board on both sides. I checked all of the electrolytic capacitors in one of them and didn't find one bad one.

The best thing about the 2050s is that you can get them cheap because they don't have the rep. that, say, the Lafayettes or Tates do.

Back to the Sanyo. Is there any pumping audible in these? It must be at least partial logic if not full.

Doug