marantz dv7600 mods
Apr 20, 2009 at 2:40 PM Thread Starter Post #1 of 16

Voodoochile

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Figured it's time to post up some details on the light mods to my Marantz DV7600. This is the same source I had at the NYC meet recently; it has PSU, coupling, and chassis damping mods at that time. This weekend I reclocked it at long last.

Short history: Used to own a NAD C541i; got a Toshi 3960 to try out some modding on; picked up the Marantz DV7600 universal player; acquired an Electrocompaniet ECD1 DAC; sold the 3600; sold the C541i; reluctantly sold the ECD1. Footnote: I loved the ECD1, did not wish to part with it, miss it, etc. It was not the end-all DAC, but it sounded beautiful. Hated to see it go. I used to run the DV7600 directly to my amp for SACD, and fed the SPDIF to the ECD1 for redbook.

Now I've had the DV7600 since new, and while it's always been a nice sounding piece, and certainly very flexible WRT formats, the sound was a bit on the heavy side. Nice bass, clean highs, but the highs were a little overshadowed by the plush low end. Not a function of the Senns, as it was consistent with Grado and AKG as well. The DV7600 shares much componentry with the ECD1, which is good. They both use the same DAC, they both utilize a discrete transistor output stage using the same transistors. The details between the two are what separates them, though. The ECD1 has a much better PSU and better coupling, amongst other things- that drive the cost of the ECD1 up, along with it's performance.

The DV7600 uses the Cirrus CS4398 DAC, CS494003 DSP, "HDAM" discrete transistor output stage. The PSU, while switchmode, uses hexfreds before the transformer and high speed soft recovery rectifiers in the audio output PSU. It has a separate PSU channel for audio, transport, and video boards, and includes line filtering of the mains. The discrete output stage is built with Toshiba 2SK369 jfets for the first stage, and complimentary output with Toshiba 2SK170 and 2SJ74 pairs... times six channels. If that rings a bell, look at the Gilmore Dynamic design. It's not the same, but it's very nice for a commercial design. Yes, there are also muting transistors, no there are no integrated op-amps. FWIW. It is certainly interesting to see so many discrete transistors in a contemporary consumer product.

Pics are terrible, but I was afraid if I waited until I got better ones, it would be another month. Overall picture of the DV7600, with some areas highlighted for reference:
overall.jpg

Section A is the PSU, B is the DAC and audio board, C is the new clock board. In between A and B is the digital output board, below B is the video output board. It's a pretty full chassis. Most of the chassis has been damped with dynamat. It's heavier near the PSU, and the transport frame is also damped. It should be noted that Marantz added foam blocks to the transport that couple it against the cover, and also includes a dense foam block between the SMPS transformer and the side of the chassis. It's a minor effort on their part, but better than nothing. I added 400 square inches total- about 2/3 of that is on the top and bottom chassis plates.

Section 1 of the psu:
psu1.jpg

Replaced the generic main filter cap with a Black Gate VK series cap. I'll admit I did this because I had the cap on hand, and the value and pitch were correct for the unit. Note the mains filter Marantz included on the board.

Sections 2 and 3 of the psu:
psu2_3.jpg

In section 2 you see the pre-reg filter caps for the audio segment of the PSU. Replaced the stock generic 330uF caps with a pair of 470uF Cerafines. Although it's hard to see behind the larger rectifiers, I also bypassed the smaller rectifiers for this segment with .01uF polypropylene caps (small green boxes). I was going to replace the rectifiers, but those from Marantz are already very fast and quiet, so no need.
In section 3, the two caps to the rear are the post-reg filter caps. I replaced the stock 47uF generics with 33uF Black Gates, bypassed with non-polar Black Gate 0.1uF NX HiQ caps. The audio PSU ripple and noise was low already, but it was reduced by almost 40% versus stock.

Section 4 and 5 of the output board:
output4_5.jpg

Section 5 is simply where I tapped the +/-8vdc for the add-on clock.
Section 4 shows the output coupling caps. Stock had 330uF generic caps. The rearmost pair are for the L/R channels. I tried several different caps and combinations here, including various polypro caps, nonpolar electros, polystyrene, PIO, and various combinations thereof. Cerafine 300uF caps were a clear improvement, and when bypassed with 1uF Auricaps, sounded better than anything else. I had high hopes for no electrolytics, or at least non-polars. The bass suffers without big electrolytics in this circuit, and there is too much offset to go without anything. My amp has no blocking caps.

This is the point the unit was at when it went to the NYC meet. The coupling caps made the most notable/audible difference, cleaning up the high end nicely while maintaining a good low end presence. The damping also seemed to tighten things up somewhat. It's been a pretty smooth running machine anyway, but it's really dead quiet now.

The final tweak (final for now anyway) was to reclock it. I've heard that this is the single best tweak for most players. In a CDP with opamp output, swapping the cheap op-amp with a nice one is a very good tweak, and is very inexpensive to change, so in that realm, I'd say that the OPA swap would be the best first tweak. This machine already had a very nice discrete output stage. There are a lot of choices out there, including Guido Tent's clock, the LC clock, the Hagclock, and a few others. I've built the Hagerman Cornet 2 phonostage already, and have a lot of respect for Jim Hagerman and his design philosophy. He's a pretty no-nonsense guy from an engineering standpoint and the gear stands up very well to scrutiny. Just look at his Bugle phono stage for example. It's difficult to top at 5 times the price. And the Trumpet stage is evidently stellar- I will never know, though! I love the Cornet 2. Finally, the Hagclock was the least expensive of the lot. The output form looks clean and stable, and it includes on-board super regulators.
clock6_C.jpg

Section 6 shows where the crystal and clock in/out caps were removed and the original from the Hagerman oscillator feeds in. It's a twisted pair line, which is fine for such a short run of less than 3".
Board C is the hagclock itself, mounted under the audio output board, right off the end of the video processor board.

I had to re-solder the oscillator feed into the hole where the original crystal's leg was mounted, rather than off the smd cap's pad, then it came right up. This player uses a somewhat odd 12.288MHz clock, and Jim was nice enough to build it with that custom frequency. Typically I have bought the board only from him, but in this case, the cost of parts+board was nearly the same as buying it built- so that was the simple way to go.

I checked the output on my frequency counter, and it was right on the money out beyond four decimal places. Looked at the output on the scope and it was beautiful. Considerably more stable than the original oscillator provided, on both axis. There appeared to be a fair amount of jitter, and some ringing on the original clock, which is no surprise. This and almost all CD players use a Pierce oscillator, which works- but that's about it. It's not especially precise, and while everything will function with jitter, in this application jitter can cause all sorts of issues. Manufacturers implement the Pierce oscillator because it uses only four or five cheap parts. Big surprise there, I know. I'm not going to dive deep into a discussion of jitter here, but suffice it to say that jitter is not your friend, and most players have it.

Here is a final picture of the overall output stage, just because it find it interesting to see:
hdam.jpg

Output caps and muting networks on the left, then the 2SK170/2SJ74 output transistors, then the 2SK369 input transistors and their bypass caps, on the far right the three chips are the DACs. It's a lot of JFETS for sure. Marantz added a nice metal shield below the PCB over the entire output stage, shielding it from the video board below. That was a task to remove to gain access to the legs of the original output caps. I was sure to replace it when finished.

I did also try taking the output from prior to the muting transistors, but the noise when operating any of the transport controls was not subtle, and the SQ improvement was not apparent. So those are still in-circuit. I may upgrade the output jacks if I decide to leave the coupling as it is now.

I'll submit a separate thread on more detailed listening impressions; this one was to focus more on the tweaking and modding. But it is a lot nicer sounding. The recoupling made a very nice improvement, and reclocking it really seems to have cleaned it up even further. The bass is not stronger, but it gives you the impression that it is because it is tighter and somewhat faster now. Some tracks show nice evidence of this. The high end is what was most improved. The placement of instruments is clearer now, and more subtle details are apparent. It seems to have a cleaner sound, but not analytical per se. It's still very lively and involving. I'm looking forward to further listening, and will report back after that time.

I have heard that this machine is available for pretty low cash these days, and I encourage anyone to pick one up. It's really very nice out of the box, playing both CD and SACD. It's got a great output stage, and with a few caps and an inexpensive clock upgrade makes a pretty formidable 1-box source. It also makes a very solid transport with an outboard DAC, but it's a waste of a pretty sweet discrete output stage.

For reference, here are some posts on the aforementioned Toshiba 3960 and NAD C541i machines and their tweaking.
 
Jul 27, 2009 at 5:10 AM Post #2 of 16

dBel84

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Thanks for pointing me in the right direction Voodoochile, somehow missed this when you originally posted the details.

I am looking at reclocking my universal player for redbook and there are a few mods here that make good sense to try ..dB
 
Jul 27, 2009 at 10:48 AM Post #3 of 16

Voodoochile

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No problem, thanks for checking it out.
I have only one tip- try to find a schematic. I had a heck of a time finding one for my player, but finally did. Nice to have all the values in place without using a magnifying glass and mirrors, as well as the circuit and pinouts.
 
Oct 27, 2009 at 3:11 AM Post #4 of 16

Non-original

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Dear Voodoochile,

Thank you for your excellent description of your mods to your DV7600. I have just scored a bargain on a barely-used example. I have ordered the HagClock from Jim and am going to begin collecting some caps to try some of your other mods. I'm curious to know if your unit is still in the same state of modification as described in your post, or have you made any additional revisions? I would agree with your description of the sound of this unit when stock. Overall it's quite good for a production player, but the upper bass is a bit full compared to the mids and treble, and the treble lacks air. I'm hopeful that the new clock and some higher quality caps will make this good player even better. I found the service manual at HiFiEngine.com (I had to register but the manual was free). Thanks again for sharing your mods and for any additional tips you may be able to offer.

Yours in appreciation,

Non-original
 
Nov 2, 2009 at 12:54 PM Post #5 of 16

Voodoochile

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Regarding the caps, I tried several caps I had on hand, and the cerafines sounded the best of those I had on hand which would fit. I did have some black gates, but the value was smaller than the cerafines, and the bass seemed to be rolled off somewhat. In all cases, the addition of the film bypass (auricap in this case) helped to sweeten it up. In fact, the stock cap bypassed with the auricap might have sounded the same, but I did not try it. I would suggest you try that first, would be easier!

As for further changes, I did take off the plastic puck feet and replace them with some EAR isodamp rubber feet I had on hand from Michael Percy. They are considerably softer than your typical rubber/vinyl feet. There is much chassis damping as well, in addition to the transport damping. I think I have gone as far as I can go with the DAC in this player, short of implementing transformers. Not having room to do that, I would pick a different player if I wanted to go that far.

Good luck with your mods, I am looking forward to the pictures!
 
Jun 3, 2010 at 5:49 PM Post #6 of 16

brave357

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I see you have great knowledge of the dv7600. I have one that will not read a sacd,dvd or cd. It would randomly read them, but not anymore. any suggestions on what to check? I have already cleaned the lens with optical cleaner. no go. any subjection is welcomed.
 
Jun 14, 2010 at 1:47 AM Post #7 of 16

sam77aus

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Hi, I have a Marantz DV7600 which I mainly use to play SACDs and I'm very interested in trying your mods, especially the reclock.
My question is will the reclock improve the performance when playing SACDs, is the clock used in the processing of DSD as well as PCM?
 
Thanks
Sam (from Australia)
 
Jun 15, 2010 at 8:29 AM Post #8 of 16

Voodoochile

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I do believe that all processing in this deck is referenced from the one master clock. I like the machine pretty well right now. The clock seems to have really tightened it up some. It was already pretty smooth, but a bit laid back.
 
While I did a few other mods, and added plenty of chassis damping, the clock alone is a pretty nice upgrade, and quite reasonable.
 
Jun 15, 2010 at 8:40 AM Post #9 of 16

Voodoochile

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@brave 357- My knowledge is pretty fundamental on this, actually. I would check all the thin ribbon connections to be sure they are square and snug in their sockets, also look at grounding connections.
 
If the discs spin up, slow down, respin, and the head is seeking all over, it sounds like it could be getting a dirty timing signal, which could be due to poor ground reference or dirty connection ribbons. Or the lens, but it sounds like you tried to address that already. There are any number of things that could cause this, including physical alignment of the reader, unfortunately. I don't know how tight the tolerance window is for such settings, but it is evidently scant. None of the affordable machines are very durable, sadly.
 
Jul 13, 2010 at 1:21 AM Post #12 of 16

sam77aus

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Thanks for that info, I noticed you used 470uF Cerafines to replace the stock 330uF caps in the pre-reg of the power supply, is this because you found them to perform better than 330uF caps, would it make much difference if I used 330uF Cerafine caps? Also what brand of 0.01uF polypropylene capacitors did you use?
 
Thank You
Sam


 
Jul 13, 2010 at 6:34 AM Post #13 of 16

Voodoochile

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Yes, the 470uF Cerafines did lower the noise somewhat. I do not recall the measurement, but it was measureable with the meter, unamplified. I had both 330uF and 470uF Cerafines on hand, and was prepared to use either one. I tried the 470s first and noted the change, so left them. For the sake of clarity and fairness, it is possible that the Cerafines of the design value would have sounded even better, but I did not try them.
 
The film caps are Auricap.
 
Jan 4, 2011 at 2:37 AM Post #14 of 16

sam77aus

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Well I finally got the hagclock and all the parts I needed to attempt Voodoochile’s Marantz DV7600 mods. I found replacing the capacitors in the PSU was fairly easy and straight forward, though I forgot to order the .01uF polypropylene capacitors. Luckily I found some .018uF polyester film capacitors (mini yellow boxes) that I had stored away years ago so I used them instead.
 
I found soldering the capacitors in the audio section rather tricky because they are soldered in on top of and underneath the circuit board. Also because I listen to a lot of music in 5.1 surround sound I decided to replace the output capacitors for all audio channels except for the subwoofer. Connecting the hagclock itself was easier than I expected, the hardest part was identifying the correct capacitors to remove, once that was done all I had to do was mount the hagclock, tap the power supply and solder the wires in.
 
After that I screwed everything back together, hooked it back up to my amp, switched it on, popped a CD in and pressed play. Well after listening to a few tracks on my CD I was pleasantly surprised, there was definitely an improvement in clarity and detail, sounds seem to be more in focus now. So I can defiantly say that I’m happy with the results, it really is worth the time, effort and money spent.
 
 

 
Jul 29, 2013 at 7:59 PM Post #15 of 16

UncleAlbert

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I am also a DV7600 owner, recently purchased used on eBay. I was a little disappointed in the 1080i upscaling at first, but later realized that it depends on the DVD. Certain discs look absolutely gorgeous! No jaggedness and the colors are so juicy! Other discs are smudgy or harsh in the facial features. This unit was probably ahead of its time in its day, but the upscaling technology has improved since then. Also, compared to other players, I noticed very little digital noise. I paired this baby with a Marantz SR5300 receiver. Yeah, that's right... 6.1 and I love it! This newfangled 7.1 surround is a hoax perpetrated on the unsuspecting consumer. Very, very few movies have 7.1 surround and I think it ridiculous to have to install two side-wall speakers for an overrated, mostly-simulated effect. But with 6.1, you just add a third rear speaker dead-center and it generates a very effective 3-D enhancement to the standard 5.1 format. Anyway, back to the DV7600. The more I use, it the more that I'm gradually falling in love with it! I just ordered some Moody Blues SACD's and I can't wait to crank "Higher And Higher" and watch my cat leap off the couch! I don't have any real complaints about the sound but yeah, it's a bit "pillowy" in the highs. It could benefit from a little more definition.
 
Is there anyone on here who would be willing to do these mods for me? Or who could recommend someone in the NYC area that knows and appreciates this unit?
 

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