RPS,

Thanks for the detailed information on parts and their part numbers. This will help me greatly as I decide how to proceed with the updates. After 42 years, I think a refresh is in order.

I'm humbled by your very generous offer to provide me with some great music to evaluate with the C9 in my system and room. This sounds like a great opportunity!
I'd be more than willing to review the music/sound and post the results here. I'm not exactly the best reviewer or writer but I think it would be fun and hopefully provide some insight to others who may be curious about the C9.
I will reach out after the holidays for sure. Thanks much!

Even though I can't set up my listening environment as the manual describes, I agree with you that one needs to try all the options on the C9 to hear what is best for their situation. With a reasonable amount of room treatment and a little work to tweak what you can with the room setup, I was able to achieve a really nice expansive soundstage that sounds very natural. It took the Decware sound to the next level. On some tracks it's a small improvement, but on others it's very obvious and very realistic. It just takes time to set the switches, listen for a while (hours/days/etc.) and then change the settings and rinse and repeat. It will be obvious at some point.

I'm also with you in the fact that it didn't take me long to hear the difference the C9 made. It was pretty much immediate, just like in your case. Maybe it's the treatment or the work I had already put in to get the speakers just right, but whatever it was, it was pretty obvious from the get-go. I'm just glad I was able to get a very big improvement even though my speaker placement couldn't be changed. (I wasn't expecting that since the manual stated multiple times 'to follow the speaker setup and listening seat exactly'.) Granted, I'm not getting the true 3D spatial sound, but I'm very, very pleased with the sound I'm getting.

Thanks for the link to the Carver video. It was humorous, cheesy, and insightful at the same time.

I too will be interested to see where this journey leads for you, JB, and I as well as any others who choose to hear what the C9 can do for their listening enjoyment.

JB,

Thanks for the pictures of the inside of your particular unit. Very interesting to see the differences in the layout.


Here's wishing you, JB, all the Decware family as well as the forumites a very Merry Christmas, New Year, and holiday season. Enjoy it y'all.

 It occurred to me that I could add a bit more information about the rebuild. Specifically, what drew me into this whole idea were the original RCA jacks used for the unit. Since they are recessed, it can be difficult to use just any interconnects. They must have skinny barrels or else they don't fit into the RCA jack. I didn't like that at all, and looked inside to see what could be done. It took a lot of experimentation to find RCA jacks that mount to the chassis and not the circuit board  itself. I ended up using Manley Labs RCA jacks and have done it that way for years. Well, since we are now inside the unit, it is a good time to take a look at the electrolytic capacitors seeing how they are 30+ years old. There are a total of 10, and it doesn't cost that much to just replace them with new and probably better caps. Of course that led to other stuff, namely the power supply. I realize that it is only needs to be tiny, but I was into replacing two of the 4136 chips with military models which happen to draw more current. FWIW, the 4136 Texas Instrument chips (there are 5) used in this unit have an unusual pinout, making the use of an adapter for other chips such as the 2134 which is a more modern version of quad amp. Yup, tried this out, with the help of a 'Brown Dog' adapter with pre-mounted with SMD chips from yes, the company named Brown Dog. This will set you back about $35 per chip replacement. Is it worth it? Not so much in my opinion, so I went with trying to find a better 4136 chip, and that is when I discovered the metal jacketed military chip that usually runs about $20 per chip if you can find them. I only have two left at this time. They sound slightly better than the originals, but hell, we are racing cars here so every little bit helps.
I have replaced numerous other components, but will tell you that each one in its own is not likely to make any difference either. From what I have gathered, replacing those two transistors is of little value since they don't amplify but just pass the signal through upon turn on just to eliminate the turn on thump.
I have tried just about anything that you can imagine, including using a battery power supply to using a separate power supply, to well, name it. Really. In the end this is where I have ended up. Like I said in the first post a rebuild of an existing unit sent to me runs around $125, and if I get the right price on eBay for a used unit, $250 is the selling price. As expected these units have become popular, and for a while people out there were selling them as reworked/tested/rebuilt/improved. This usually meant that the little red light cam on when plugged in and nothing more. If they did show the inside, I was immediately able to tell if they were ever taken apart or not. Maybe I will give up that secret later, depending on the interest of these units, and yes, they are truly worth having in a system. Many other brands have attempted in various ways to replicate this audio illusion and I have listened to a number of them. This unit by far and away the best.

4krow,

Thanks for all the details and information regarding the C9. Very informative and nice pics as well. I am considering getting my unit refreshed and updated, especially the RCA's. This is very intriguing.

Don't get too excited about the first photo with rack handles. I am still trying to convince the guy who makes these new front panels with handles to make more of them. And of course, they aren't cheap at nearly $100 extra, but you have to admit they are pretty (and accurate logo and lettering too).
You will notice that I didn't change out the transformer in that unit either. It was enough cost to my customer that he chose the front panel but not a new transformer. These days, I am not so flexible and so a new transformer is automatic with the rebuild price.

Donnie I found these which I think attempt with some success to explain the device:

https://www.highfidelityreview.com/carver-c9.html

http://www.magneticmadness.com/2017/02/carver-c-9-sonic-hologram-generator.html

Donnie,

My understanding is that the Carver C9 attempts to eliminate or minimize inter-aural crosstalk. It tries to prevent your left ear from hearing sounds from the right speaker that it shouldn't be hearing and vice versa. It basically sends an additional signal (along with the left speaker's normal signal) to cancel out sounds from the right speaker that would confuse the brain. I think like an inverted phase of that signal. I don't understand the technical details, but it does more than just that and there are delay considerations as well. It does not add echo or anything like that, in fact, it's what it takes away (inter-aural crosstalk) in terms of correcting what stereo should actually sound like. It tries to restore the reality in live and real-life music and sounds. Normal stereo can sound really good but the C9 brings it more into true perspective. When your left ear hears an instrument from the left speaker, it is also potentially hearing it from the right speaker as well (depending on the recording) but a few milliseconds later. This confuses the brain a little but the C9 will counter that particular signal and allow you to hear it in the proper context. You still get the phantom center channel (when it's there) and it also allows you to hear the various instruments/voices coming from the various locations while still maintaining proper reverberation as it moves through the room. It brings the instruments into focus in their own space and creates an even more convincingly wide soundstage. I hope I'm making sense here, so someone please correct me if I'm wrong or I'm missing important information.

The thing is, if you read the manual, it highlights the fact that you MUST follow the setup exactly or you won't benefit from the full effect that the C9 has to offer. It wants you to pull the speakers out and close together (maybe no more than 5' apart center cone to center cone) with precise distance to the listener, etc. Doing this is supposed to give you a fantastic 3D sound stage in all its glory. (if it's in the recording.... Classical music doesn't lend itself so much to this though)

Because of my room and setup, I am unable to conform to the 'correct' arrangement described in the manual. I am however able to get a great effect from the C9 regardless. (to my surprise actually) I thought without the ability to setup the speakers and listening chair just so, I would not benefit much from the C9. I couldn't have been more wrong. I don't get the 3D sound all around me, or things behind me, or sounds circling around my head, but I get a very realistic and expansive soundstage. It brings the great Decware sound to the next level for me. I don't know if others would get the same results without moving their speakers or putting in at least some modest room treatment, but if you have your room as good as it can sound in stereo, then I'm willing to bet you would benefit to a good degree with the C9. Maybe it's my unique room, acoustics, setup, I don't know, but I'm really liking what I'm hearing.

I hope this helps and doesn't confuse anyone.

4krow,

Please take a look on page 5 starting at reply #239. It attempts to show the circumvented fuse, the iffy soldering to the spare receptacle, and the current state of the transformer. Reply #241 shows the full board (albeit at a distance). If you would like more or different pictures just let me know.

It also looks like the 4 large yellow caps have been replaced at some point, but I don't know for sure. Looking at the latest schematic for the latest Rev (F) it shows that two caps should be 16V and two should be 25V. It looks like all 4 of those yellow caps are 16V. Maybe it's because my unit (#606) being part of the original builds only called for 16V. Just wanted to point that out in case it matters.