No, there isn't a soft start circuit. The in-rush current draw is enough to dim a light on the same breaker but doesn't seem bad enough to need soft start.
To get to the amp power supply takes a lot of disassembly. If you remove the back panel and work your way from there its a lot easier than trying to do it all from the top.
Not a chance.
Is there a way to re-use the volume control section also? 🙂
I.e. rca inputs ---> remote/volume control section ---> amp section.
When mine arrives I'll try and figure it out, but if anyone has any tips.... feel free to share. 🙂
I.e. rca inputs ---> remote/volume control section ---> amp section.
When mine arrives I'll try and figure it out, but if anyone has any tips.... feel free to share. 🙂
Well, after almost 8 hours of straight labor I have done a complete makeover to one of my moto's.
I started out by changing the over-current trip limit to allow for >4 ohm loads, then I replaced the 2.2uf electrolytic input caps with 3.3uf Jantzen MKP's.
Next I added another 10,000uf per rail to the supply. I took 2 caps from another moto supply board so they all match. I also changed out the 5v and 10v supply caps with Panasonic FC's and added some bypass caps to empty spots on the board.
The last and most difficult mod I did was replace the spring output terminals with binding posts. This took nearly 3 hours and 2 trips to the hardware store, not to mention extremely sore fingers. It wasn't fun at all.
Oh, I forgot I replaced the power cable with an IEC jack. Makes the unit look pro.😀
Here's a pic of the amp board with new input caps.....
http://i2.tinypic.com/2643q7s.jpg
Power supply board.....
http://i4.tinypic.com/2643r00.jpg
And lastly the back of the unit with binding posts and IEC jack.....
http://i2.tinypic.com/2643spi.jpg
I don't plan on doing this again any time soon; royal PITA.
I started out by changing the over-current trip limit to allow for >4 ohm loads, then I replaced the 2.2uf electrolytic input caps with 3.3uf Jantzen MKP's.
Next I added another 10,000uf per rail to the supply. I took 2 caps from another moto supply board so they all match. I also changed out the 5v and 10v supply caps with Panasonic FC's and added some bypass caps to empty spots on the board.
The last and most difficult mod I did was replace the spring output terminals with binding posts. This took nearly 3 hours and 2 trips to the hardware store, not to mention extremely sore fingers. It wasn't fun at all.
Oh, I forgot I replaced the power cable with an IEC jack. Makes the unit look pro.😀
Here's a pic of the amp board with new input caps.....
http://i2.tinypic.com/2643q7s.jpg
Power supply board.....
http://i4.tinypic.com/2643r00.jpg
And lastly the back of the unit with binding posts and IEC jack.....
http://i2.tinypic.com/2643spi.jpg
I don't plan on doing this again any time soon; royal PITA.
john65b said:
Let me make it through work tonight on my 2 hours of sleep and then come home and go into a coma for about 12 hours and then when I finally awake I'll try to pull myself together enough to answer that question.
Member
Joined 2003
Nice work! I am still shopping for one of these units myself, I think modifying one of these could make for an exiting project. I look forward to hearing what you think of your modified amp.
theAnonymous1,
It looks great! I think I may go with those caps also, they look like they mean business!
I pulled the hammer on moto #4. Two may end up for sale some day, the other two I'm keeping. I plan to modify the input caps on all four.
Thanks for the pics! Great job.
It looks great! I think I may go with those caps also, they look like they mean business!
I pulled the hammer on moto #4. Two may end up for sale some day, the other two I'm keeping. I plan to modify the input caps on all four.
Thanks for the pics! Great job.
DcibeL, You said "you were shopping for one of these units." This ebay seller is the place. I am very happy with all three, and one more is on the way. He is a great ebay seller, 100 percent positive feedback.
http://cgi.ebay.com/Motorola-DCP501...ryZ14981QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
http://cgi.ebay.com/Motorola-DCP501...ryZ14981QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
Member
Joined 2003
Well,
I've been running mine stock for about 2 weeks. I swear it's sounding better and better. Is it just me, or do these things really break in? The dcp501 is such a complex unit that any changes ought to average out. But I swear it seems to have smoothed and mellowed. My imagination?
Only problem is that I can't get the coax input working now. Wanted to test the digital input again. Gotta find out what's up.
I've been running mine stock for about 2 weeks. I swear it's sounding better and better. Is it just me, or do these things really break in? The dcp501 is such a complex unit that any changes ought to average out. But I swear it seems to have smoothed and mellowed. My imagination?
Only problem is that I can't get the coax input working now. Wanted to test the digital input again. Gotta find out what's up.
I agree, moto #1 has by far the most hours on it. I think it is sounding much better now, and that's from the moto DVD player! I also really think the chip is breaking in nicely, I think it will open up more, I opnly have about 40 hours on it.
I've been listening to my modded moto now for several days and I have to say it sounds damn good.
Changing the input caps made a night and day difference, as I expected it too.
I remember reading a few pages back about comments on the DVD player sound quality being not so great. I honestly have to say I can't tell any difference between using the built in DVD player or using my PC's CD-ROM through SPDIF optical in. They both sound great.😎
I've only been using the moto as a stereo amp as I only have 2 speakers, so I can't comment on how well the surround processing works.
I'm going to try something next that isn't a recommended practice. There is enough room on top of the transformer for another one to just barely fit. I'm going to parallel another transformer and see what kind of power I can get out of this thing, hopefully not setting anything on fire in the process.
The only other thing I would like to do is add more heatsink, but there just isn't any room.🙁
Changing the input caps made a night and day difference, as I expected it too.
I remember reading a few pages back about comments on the DVD player sound quality being not so great. I honestly have to say I can't tell any difference between using the built in DVD player or using my PC's CD-ROM through SPDIF optical in. They both sound great.😎
I've only been using the moto as a stereo amp as I only have 2 speakers, so I can't comment on how well the surround processing works.
I'm going to try something next that isn't a recommended practice. There is enough room on top of the transformer for another one to just barely fit. I'm going to parallel another transformer and see what kind of power I can get out of this thing, hopefully not setting anything on fire in the process.
The only other thing I would like to do is add more heatsink, but there just isn't any room.🙁
Has anybody figured out how the volume control works? Is it done via the DAC's or via a volume control chip? I'm interested in getting this receiver, but also want to mod it for 5 ch input.
I haven't taken the front of the unit apart to trace out the volume control, but the DSP board uses CS4391 DAC's which do digital volume control.
http://www.cirruslogic.com/en/pubs/proBulletin/cs4391pi.pdf
http://www.cirruslogic.com/en/pubs/proBulletin/cs4391pi.pdf
I just got mine and played around with it, just to make sure everything worked. It sounds REALLY nice! I even tried some 192kbs VBR mp3s (manual says to use 128kbs) and they sounded fine, ditto a CDR mix of Linda Ronstadt. I'm glad I saw this message!
Tom.
Tom.
Thanks for the report Anonymous1. Good to know that progress can be made.
I did a little critical listening today, too. Hooked up an AMP6 with Janzten input caps to the pre outs of the 501. Big difference! The owners of AMP6 and Charlize amps have nothing to worry about - yet.
The AMP6 was better in every way. Smoother, richer, more dynamic , better imaging. The Motorola sounded dull and flat by comparison. And that's using the 501 as preamp!
When using a passive preamp (just a 50K pot) the AMP6 sound was even better, the improvement was as big as from one power amp to the next. More lively, fuller, richer. I guess all the DSP and D/A conversion in the 501 is killing the fun.
So to my ears the 501 has along way to go. Not that it sounds bad - but compared to the AMP6 the 501 is kind of dull, lacking in musicality. Things really come alive on the AMP6.
But maybe going straight to the Motorola amp board thru good caps will bring the 501 up to the level of its little brother. More work to do!
Also listened to the analog vs. coax input. This time I thought the coax input wasn't bad, maybe better than the analog input. And it "should" be. No extra D/A-A/D conversion to go thru. Compared to the analog input, the coax input is wider and has more "bite." I don't know which is more accurate. The coax input does sound more detailed, more "air" and a wider sound stage, the analog input is smoother, maybe rolled off in the high end, images is more centered, not as wide. But it's hard to say which is the "real deal." I'll try some other amps to see if the "real sound" makes itself known.
Fun! 😀 😎 😀
I did a little critical listening today, too. Hooked up an AMP6 with Janzten input caps to the pre outs of the 501. Big difference! The owners of AMP6 and Charlize amps have nothing to worry about - yet.
The AMP6 was better in every way. Smoother, richer, more dynamic , better imaging. The Motorola sounded dull and flat by comparison. And that's using the 501 as preamp!
When using a passive preamp (just a 50K pot) the AMP6 sound was even better, the improvement was as big as from one power amp to the next. More lively, fuller, richer. I guess all the DSP and D/A conversion in the 501 is killing the fun.
So to my ears the 501 has along way to go. Not that it sounds bad - but compared to the AMP6 the 501 is kind of dull, lacking in musicality. Things really come alive on the AMP6.
But maybe going straight to the Motorola amp board thru good caps will bring the 501 up to the level of its little brother. More work to do!
Also listened to the analog vs. coax input. This time I thought the coax input wasn't bad, maybe better than the analog input. And it "should" be. No extra D/A-A/D conversion to go thru. Compared to the analog input, the coax input is wider and has more "bite." I don't know which is more accurate. The coax input does sound more detailed, more "air" and a wider sound stage, the analog input is smoother, maybe rolled off in the high end, images is more centered, not as wide. But it's hard to say which is the "real deal." I'll try some other amps to see if the "real sound" makes itself known.
Fun! 😀 😎 😀