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Old 3rd November 2011, 05:26 PM   #1
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Default BEWARE!

I, like most DIY audio members, like to hear good sounds and that usually means modding equipment to our liking. Everyone has different Idea as to what is "Great Sound". That I believe is our personnel choice. I have modded a Marantz 67SE, Aracam Alpha 5, Nakamichi Player 4, and a Magnavox CDB-630. Some to Destruction, by my own doings. I decided to choose my next victim, and after reading "Reviews" picked an Adcom GCD-700. Of course, price was an issue, but it was universally praised as an excellent sounding unit. It was also touted as a "quality unit". Bought one that had some tracking issues, Taking a chance(seller completely honest, not a factor in my discovery). What I found was quite a shock! I received the unit and immediately took off the cover to dig into the laser unit(maybe adjustment). The box indicated that it was built in Japan, but immediately it was obvious to an experience DIY it was made in China. Sure enough, the name plate confirmed it. Many of the large caps had spewed out on the horrible constructed circuit board. Parts were not only of inferior quality, but not place in alignment, and had unequal length leads. Some parts where against the board others with half inch lead lengths. The player had 2, I repeat, two regulators. It had been repaired in the past, one capacitor of much greater quality. I recognized this unit. I pulled out my unmodified, working, Denon DCM-260, exactly the same mechanism, frame chassis, and even the power transformer. I was SHOCK to see a $200 unit with the same basic chassis as a $1000(?) unit. The denon parts where laid out even, aligned, with normal positioning found on most units. None of the parts had failed yet. Both units are from the mid 90's. How did this unit get such rave reviews? Does this prove that quality(including parts) don't make the difference between MID FI and HI FI. I didn't even find a medium review anywhere on the Adcom. Just as a side note, all the Philips chip/mech units are still working some 26 years old, all my Sony units have failed at least once.
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File Type: jpg Adcom GCD-700.jpg (660.2 KB, 957 views)
File Type: jpg denon DCM-260.jpg (603.9 KB, 908 views)
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Old 4th November 2011, 02:25 AM   #2
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For me Phillips and Denon are the only brands that I want to see... Exactly because of construction quality.
The "fancy" brands don't have their own factories, they just order the same parts from the same manufacturers as everybody else.
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Old 4th November 2011, 02:53 AM   #3
qusp is offline qusp  Australia
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so the 1000 dollar adcom is a copy of a 200 dollar denon?
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Old 4th November 2011, 03:45 AM   #4
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Quote:
Originally Posted by optimationman View Post
I decided to choose my next victim, and after reading "Reviews" picked an Adcom GCD-700. Of course, price was an issue, but it was universally praised as an excellent sounding unit. It was also touted as a "quality unit". .... I was SHOCK to see a $200 unit with the same basic chassis as a $1000(?) unit. ... How did this unit get such rave reviews? Does this prove that quality(including parts) don't make the difference between MID FI and HI FI. I didn't even find a medium review anywhere on the Adcom.
LOL - proof (as if it were needed) that the reviewers either talk through an orifice not located in the region of their face AND/OR that they are as suseptible as anyone to a flashy exterior and a marketing spin.

Audiophools the world over should consider this in the context of cables, "audio quality" capacitors or semi-conductors etc etc.
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Old 4th November 2011, 04:37 AM   #5
Luke is offline Luke  New Zealand
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but the electronics are different, surely that could make all the diff in the world?
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Old 4th November 2011, 10:31 AM   #6
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In my experience Denon uses good capacitors too...
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Old 4th November 2011, 11:49 AM   #7
kvholio is offline kvholio  Netherlands
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The electronics in the ADCOM appear to be completely different from the Denon, this could explain sonic differences.
I'm not too surprised they're both using the same transport, maybe ADCOM didn't want to spend the $$$ in developing their own transport.

Quote:
Originally Posted by SoNic_real_one View Post
In my experience Denon uses good capacitors too...
In a Denon DCD-1560 i bought ~2 years ago, all caps were fine,
except for two powersupply-caps that were located very close to the small heatsinks used by the powersupply-regulators.
Roughly estimated working-temperature would be 50-60 degrees Celsius.
They showed no visual signs of failure, but looking at the powerlines on a scope showed a lot of hf-crap so i replaced them.
Voila, the hf-crap was gone,and sound-quality notably improved.
Since it sounds fine to my ears and appears to be well engineered, i've done no modifications to it.
Maybe i'll fit those regulators with larger heatsinks to avoid premature failure of the caps in the future.

Regards,

Klaas
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Old 4th November 2011, 08:24 PM   #8
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If you replace the OpAmps in that DCD-1560 with something else better, you will have a very nice player.
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Old 5th November 2011, 02:05 PM   #9
kvholio is offline kvholio  Netherlands
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Yes, it sounds tempting to swap the NE5532's for something better.
Opinions on the merits of swapping opamps in existing equipment seem to differ though.
Another option for a future upgrade would be adding an external DAC,
the Denon transport surely looks like it's built to last.

Best regards,

Klaas
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Old 5th November 2011, 02:56 PM   #10
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Well, swapping the opamps will convince you within seconds of the opposite. Opinions of others won't do you any good, it is your ears that will decide.

Even better and cheaper (which might appeal to you because you are Dutch too ) would be a new internal DAC. No need for SPDIF and less jitter.

Just throw in:

- an ES9023 with 2 x power supplies 3.3 V and proper decoupling. One 3.3 V reg for the chip, the other one for the 50 MHz XO.
- a low jitter clock for the mainboard of the player
- remove the muting transistors if it has those (I forgot). Only relevant if you reuse the original output RCA's.

It would be best to design a small drop-in PCB with the chip and regs on it. Make that 2 x ADP151 and feed those with the players 5 V, preferably a clean 5 V. No need for an output stage so you won't need new opamps at all. Total cost : less than 25 Euro excluding a low jitter clock. Personally I would replace all caps because of their age. They sure won't be in optimal shape after all those years. Also the heatsinks should be added ! There is no excuse making the same mistake as the manufacturer did for a second time.

Marvellous sound quality can be done cheap too nowadays as DAC chips don't cost as much as the older ones. They are way better than most older chips too.
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Last edited by jean-paul; 5th November 2011 at 03:14 PM.
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