Denon POA 6600 Thread

[Soundscape]

OK, so here is a thought.

If you are replacing IC502, and are installing an op-amp on/with an adapter board with exposed leads like the one that I have, Don't do it with your left hand while your right hand is grounded to the case.

Because when I did that (and yes, the amp was unplugged from the mains, I am not that stupid), I discharged something.
Through... ...me!
And from the amount of juice I am guessing that it was all 4 main filter caps (10,000µF x 4).

It was... ...uncomfortable(!)... ...and at the same time... ...breathtaking(!).

I can state with conviction that you do not want to do this.

,
James

Welcome to the filter cap dance club!

Glad you're ok man. Can we have a video next time though?

 

[djkcb]

Great thread with loads of info. I have two 6600 that i'm currently working on.

I plan to replace according to the list below. According to tips from bratwurst, these replacement components could work. What do you say? Previous owners have already replaced some transistors but I can't really tell if they work as intended. Considering replacing them all again.

Ref Number	Original part	Today replaced with.	Planning to replace
TR500 & TR501	2SK184C	Not replaced yet	to 2SK209-GR
TR523, TR510, TR508, TR504, TR505	2SA1321	F423	to KSA1381ESTU
TR525, TR522, TR509, TR506,TR507	2SC3334	BF422	to KSC3503DSTU
TR502 & TR503	2SC2705	JCC3	to KSC3503DSTU
IC501	NJM082DT	Not replaced yet	to OPA1642AIDR
IC502	M5218P	Not replaced yet	to OPA1656ID

Thanks in advance.

 

[Bratwurst7s]

Great thread with loads of info. I have two 6600 that i'm currently working on.

I plan to replace according to the list below. According to tips from bratwurst, these replacement components could work. What do you say? Previous owners have already replaced some transistors but I can't really tell if they work as intended. Considering replacing them all again.

Ref Number	Original part	Today replaced with.	Planning to replace
TR500 & TR501	2SK184C	Not replaced yet	to 2SK209-GR
TR523, TR510, TR508, TR504, TR505	2SA1321	F423	to KSA1381ESTU
TR525, TR522, TR509, TR506,TR507	2SC3334	BF422	to KSC3503DSTU
TR502 & TR503	2SC2705	JCC3	to KSC3503DSTU
IC501	NJM082DT	Not replaced yet	to OPA1642AIDR
IC502	M5218P	Not replaced yet	to OPA1656ID

Thanks in advance.

If you have not replaced TR500/501 and are still having problems then in my opinion they are highly suspect. I would replace them. The mounting method can be found earlier in this thread, post #44.

I have no experience with F423, BF422 or JCC3 so I can't make any useful comments regarding them but can state that the KSA1381ESTU/KSC3503DSTU have been working very well in my amps.

,
James

 

[djkcb]

If you have not replaced TR500/501 and are still having problems then in my opinion they are highly suspect. I would replace them. The mounting method can be found earlier in this thread, post #44.

I have no experience with F423, BF422 or JCC3 so I can't make any useful comments regarding them but can state that the KSA1381ESTU/KSC3503DSTU have been working very well in my amps.

,
James

Thanks man! Ok, great stuff. I will order them. Let you know how it goes for me.=)

 

[Malteser]

No problem, I'm happy to be able to help.
Good luck.

,
James

Many thanks again for your help James, this is the final result for my output board repairs/upgrades. Happily all fitted/soldered for £30 by a private school IT assistant to earn extra money (as schools assistants in UK do not get well paid).

 

[Bratwurst7s]

Many thanks again for your help James, this is the final result for my output board repairs/upgrades. Happily all fitted/soldered for £30 by a private school IT assistant to earn extra money (as schools assistants in UK do not get well paid).

Nice! I hope that you enjoy your amps as much as I am enjoying mine. They took a lot of work but it was worth it.

,
James

 

[djkcb]

Thanks man! Ok, great stuff. I will order them. Let you know how it goes for me.=)

@Bratwurst7s

Hello! Hope all is good. I’ve just finished replacing components on the main board and I’m still stuck in protection mode. As I’m an amateur I would appreciate some help. I’m reading +81v but not getting my -81v. Shouldn’t I be reading -81v from black and blue outputs from Power supply? I’m getting almost nothing?

Under dimbulb and I charges up and turns of as it should. So it seemes ok.

Edit removing CN13 gets me out of protection mode. Any ideas?

Removing CN12 also gets me out.

 

[Bratwurst7s]

@Bratwurst7s

Hello! Hope all is good. I’ve just finished replacing components on the main board and I’m still stuck in protection mode. As I’m an amateur I would appreciate some help. I’m reading +81v but not getting my -81v. Shouldn’t I be reading -81v from black and blue outputs from Power supply? I’m getting almost nothing?

Under dimbulb and I charges up and turns of as it should. So it seemes ok.

Edit removing CN13 gets me out of protection mode. Any ideas?

Removing CN12 also gets me out.

Have you checked the fuse for minus 80v? There is a separate fuse for the plus and minus 80v.

 

[djkcb]

E

@Bratwurst7s

Hello! Hope all is good. I’ve just finished replacing components on the main board and I’m still stuck in protection mode. As I’m an amateur I would appreciate some help. I’m reading +81v but not getting my -81v. Shouldn’t I be reading -81v from black and blue outputs from Power supply? I’m getting almost nothing?

Under dimbulb and I charges up and turns of as it should. So it seemes ok.

Edit removing CN13 gets me out of protection mode. Any ideas?

Have you checked the fuse for minus 80v? There is a separate fuse for the plus and minus 80v.

Thanks. Yes i must have missed checking that fuse now replaced and now my bulb lights up like crazy. Humm i have tested and testet but i must be missions something

 

[djkcb]

Have you checked the fuse for minus 80v? There is a separate fuse for the plus and minus 80v.

Making progress. Now come out of protection mode but light bulb does not go off completely and it seems to become brighter and brighter over time. Seemes to be some heat generating quickly. Any ideas?

Not getting right voltages eather had some smoke coming from part in area at tr512. I pulled it again and reading good but many it is bad.

I’m having another look at both 512 and 511 tomorrow

 

[Bratwurst7s]

Are TR511/512 original? Did you replace D509?

I was skeptical about using the MJE15032G/MJE1533G as replacements for 511/512 but they are working perfectly.

These amps are very complex and the truth is that they are a good bit over my head when it comes to understanding them.

Oh, put your meter minus lead on the ground ring at the lower left corner of the main amp board and check your voltages with the plus lead.

 

[Bratwurst7s]

Thanks. Yes i must have missed checking that fuse now replaced and now my bulb lights up like crazy. Humm i have tested and testet but i must be missions something

I missed that I had a bad fuse in my second amp and made a lot of mistakes trying to figure out what was happening. I felt really dumb after that.

 

[djkcb]

I missed that I had a bad fuse in my second amp and made a lot of mistakes trying to figure out what was happening. I felt really dumb after that.

For me it’s easy to miss stuff.

 

[djkcb]

Are TR511/512 original? Did you replace D509?

I was skeptical about using the MJE15032G/MJE1533G as replacements for 511/512 but they are working perfectly.

These amps are very complex and the truth is that they are a good bit over my head when it comes to understanding them.

Oh, put your meter minus lead on the ground ring at the lower left corner of the main amp board and check your voltages with the plus lead.

I have replaced all except tr521 and 524 and the ones above, that are original. I will order replacements I thing. Just going to check once again. They are acting weird in circuit, specially 512.

 

[AK Builder]

I have searched this site as well as others and have a question I have not been able to find an answer to - at least not a definitive one. I have come across statements saying the POA 6600 is a better version than the 6600A. As this seems by rights the most definitive (and recent) Denon 6600/6600A monoblock discussion - does anyone have any thoughts on choosing one over the other as I expect I'll buy a pair of one or the other at some point soon. I'm currently using a Denon POA 2400A via a Nakamichi CA-5 preamp to drive four Polk Monitor 10 speakers and it does beautifully. I get the sense the "A" designation in the Denons means mid-production improvements so I'm surprised to hear that the 6600A may not be as desirable as the 6600. Any thoughts from people running these amps would be much appreciated.

 

[Bratwurst7s]

I have searched this site as well as others and have a question I have not been able to find an answer to - at least not a definitive one. I have come across statements saying the POA 6600 is a better version than the 6600A. As this seems by rights the most definitive (and recent) Denon 6600/6600A monoblock discussion - does anyone have any thoughts on choosing one over the other as I expect I'll buy a pair of one or the other at some point soon. I'm currently using a Denon POA 2400A via a Nakamichi CA-5 preamp to drive four Polk Monitor 10 speakers and it does beautifully. I get the sense the "A" designation in the Denons means mid-production improvements so I'm surprised to hear that the 6600A may not be as desirable as the 6600. Any thoughts from people running these amps would be much appreciated.

Well, I wish that I could inform you concerning this but the POA 6600 is the only Denon amp that I have owned, used or listened to. Their CD players I can talk about.

It appears tho that the "A" models are considerably changed internally, and especially the switch to an opto-coupler bias control section. Perhaps it might be easier to repair than the non-A model, but again, I have not had my hands on one. The SM for the A is in the AK database btw, although it is a German version.

https://akdatabase.org/AKview/displayimage.php?pos=-3784

,
James

 

[AK Builder]

Well, I wish that I could inform you concerning this but the POA 6600 is the only Denon amp that I have owned, used or listened to. Their CD players I can talk about.

It appears tho that the "A" models are considerably changed internally, and especially the switch to an opto-coupler bias control section. Perhaps it might be easier to repair than the non-A model, but again, I have not had my hands on one. The SM for the A is in the AK database btw, although it is a German version.

https://akdatabase.org/AKview/displayimage.php?pos=-3784

,
James

Thanks for the link to the service manual. I try to reproduce decent hard copies of all the stuff I own. It will be interesting to see if someone else will be able to speak to a comparison between the two versions. It's been nagging at me for a while. Great thread btw. Although I'm not well versed in the repair work, I come from the trades and can appreciate the amount of knowledge and critical thinking skills that took place here to solve the problems -Ilya

 

[Bratwurst7s]

Thanks for the kind words Ilya.

It would be interesting to be able to compare them for sure, but not interesting enough for me to lay out the money for a pair.

The 6600's were a bit of an experiment for me. I was actually quite happy with my Yamaha MX-1 but really wanted to hear what some good monoblocks could do for me. I have owned and modded a lot of Denon 90's(+) cd players and liked them a lot, and liked the looks (inside) of the 6600's so decided to take a chance. First time in 40 years that I moved away from Yamaha amplifiers.

I would say that with the original op-amps the Denons sounded much on par with the MX-1 with the exception of a better sound stage. With the new Burr Brown op-amps they sound decidedly better. I will not willingly part with them now.

Sometime next year I will start working on my 3rd 6600 to have it as a backup.

,
James

 

[AK Builder]

Thanks for the kind words Ilya.

It would be interesting to be able to compare them for sure, but not interesting enough for me to lay out the money for a pair.

The 6600's were a bit of an experiment for me. I was actually quite happy with my Yamaha MX-1 but really wanted to hear what some good monoblocks could do for me. I have owned and modded a lot of Denon 90's(+) cd players and liked them a lot, and liked the looks (inside) of the 6600's so decided to take a chance. First time in 40 years that I moved away from Yamaha amplifiers.

I would say that with the original op-amps the Denons sounded much on par with the MX-1 with the exception of a better sound stage. With the new Burr Brown op-amps they sound decidedly better. I will not willingly part with them now.

Sometime next year I will start working on my 3rd 6600 to have it as a backup.

,
James

 

[AK Builder]

Well here's an update. After many loyal years, my POA 2400A finally needed service and in the interim I went ahead and scratched an itch and bought a pair of restored POA 6600A's. I was using the 2400A to drive a pair of Polk monitor 10A speakers rated at 6 ohms and a pair of Polk monitor 10 series 2 at rated at 8 ohms. The 2400A drove all 4 speakers just fine - although I admit I never pushed it hard. My question is....what can I expect if I use one of the monoblocks to drive the pair of 6 ohm speakers and the other monoblock to drive the pair of 8 ohm speakers? From what I can tell reading the owners manual, the 8 ohm pair should be fine. It's the 6 ohm pair that's running out of the amps specified impedance range of 8-16 ohms when running in A + B mode. Please correct me if I'm wrong, but I think the impedance running the two 6 ohm speakers in A + B mode is 3 ohms. Am I playing with fire here? I can't imagine I'm the only one driving two vintage speakers with one of these beasts. Any input on this is much appreciated. -Ilya