Seems to have worked this time. As you can see, there are some mods to the main amp. The first differential stage now has a proper current mirror and I left the emitter resistors in so I could keep the adjuster. The emitter resistors are now one tenth the size because the originals reduced the efficiency of the stage. Also note the constant current circuitry which now doesn't rely on the stability of the -18V supply. This includes a constant current in the second stage which improves the efficiency by a factor of 100. Make sure you use the LF411A as the servo since it's rated at 22V instead of 18 V as in the standard LF411. I kept the adjuster even though there is a servo so that the servo doesn't have to work too hard. Put a voltmeter on the op amp output and adjust the voltage to zero.
NAD 2200PE upgrading
- Thread starter streetwise
- Start date
I have been recapping and modding NAD 2200s for a while now- and wanted to give some details back to the AK community:
I have selected a number of mods from Pilots and others listings, and these seem to make the majority of difference:
C215-218- yes replacing the 2.2uf 50v with 470uf 50v makes quite a difference, "more bass" and better dynamics- nichicon PW
C111-114- I have not been able to find COG Ceramics to replace these- however I added 47uf 50v in parallel with each of these (across the 18v supply lines) and this again seemed to provide better dynamics - nichicon PW
I tried Pilots swapping of C109, C110 to 2.2uf 50v Wima- but ended up going back to Nichicon FG 10uf 50v- which gave more solid square wave response at frequencies below 100Hz
C107,C108- these were 820pf ceramics (circuit states 1000pf film)- so replaced these with WIMA 100pf 50v film
C203, C204- I tried a few versions (2.2uf Film, 10uf Film- both WIMA, Nichicon KL, Nichicon FG) and finally settled on ELNA SIMLIC II 10uf 50v- for me this kept the detail and was smoothest- also kept the LF square wave tidy.
I replaced the 2043DD IC's with LM49860- I had tried the OPA2134 (which is an IC I like), but again for me the LM49860 is better suited to the amp-perhaps as it is BJT as is the 2043DD
else I replaced all the other electros as follows:
Power supply- Nichicon PW same values
Power amp- all PW except c223, C224, C311, C312, C313,C314- all FG and C203,C204- ELNA Simlic II as mentioned
input amp- c109,c110 FG, C115,C116 Nichicon KA
plus the 47uf mentioned above
10000uf 80v with Nichicon or equivalent
the 10000uf 120v are unobtainable, and the 160V versions are both expensive and dont fit- so I have some 10000uf 125v sourced from China- which I plan to try, though part of me is worried they will explode- so as long as the original caps are within spec(which they are at present) I tend to leave them alone.
for me this is the best NAD mod yet- more bass, better dynamics and measures well, though there is some low frequency phase shift and roll off from about 50hz downwards-the LAB inputs less so as expected.
one thought is to bypass the 10k ufs with a film cap (1uf?)- but again I have not tried this as yet.
I have selected a number of mods from Pilots and others listings, and these seem to make the majority of difference:
C215-218- yes replacing the 2.2uf 50v with 470uf 50v makes quite a difference, "more bass" and better dynamics- nichicon PW
C111-114- I have not been able to find COG Ceramics to replace these- however I added 47uf 50v in parallel with each of these (across the 18v supply lines) and this again seemed to provide better dynamics - nichicon PW
I tried Pilots swapping of C109, C110 to 2.2uf 50v Wima- but ended up going back to Nichicon FG 10uf 50v- which gave more solid square wave response at frequencies below 100Hz
C107,C108- these were 820pf ceramics (circuit states 1000pf film)- so replaced these with WIMA 100pf 50v film
C203, C204- I tried a few versions (2.2uf Film, 10uf Film- both WIMA, Nichicon KL, Nichicon FG) and finally settled on ELNA SIMLIC II 10uf 50v- for me this kept the detail and was smoothest- also kept the LF square wave tidy.
I replaced the 2043DD IC's with LM49860- I had tried the OPA2134 (which is an IC I like), but again for me the LM49860 is better suited to the amp-perhaps as it is BJT as is the 2043DD
else I replaced all the other electros as follows:
Power supply- Nichicon PW same values
Power amp- all PW except c223, C224, C311, C312, C313,C314- all FG and C203,C204- ELNA Simlic II as mentioned
input amp- c109,c110 FG, C115,C116 Nichicon KA
plus the 47uf mentioned above
10000uf 80v with Nichicon or equivalent
the 10000uf 120v are unobtainable, and the 160V versions are both expensive and dont fit- so I have some 10000uf 125v sourced from China- which I plan to try, though part of me is worried they will explode- so as long as the original caps are within spec(which they are at present) I tend to leave them alone.
for me this is the best NAD mod yet- more bass, better dynamics and measures well, though there is some low frequency phase shift and roll off from about 50hz downwards-the LAB inputs less so as expected.
one thought is to bypass the 10k ufs with a film cap (1uf?)- but again I have not tried this as yet.
Hi Peter,
Digging up your post in this old thread, or is it digging up this old thread with your post in it? I have a 2200, two 2700s and a 2600 I want to start work on, and I had a couple of questions :
C111-114, any particular COG ceramic? Mouser has this Vishay / Sprague one 75-2C20COG103J050B
C107-108, did you mean to say you replaced them with 1000pF WIMA films? Your post above said 100pF.
Replacing the 2043 op-amps, what's an LM49860? Mouser has an LME49860 but it's surface mount only.
Lee.
HI LEE
Yes I did find COG ceramics and opted for KEMET -80-C330C103J5G for C111-114.
well spotted typo- yes replaced these with 1000pf WIMA
The OPamps- yes the LME49860 are now surface mount only- so I will now be using LME49720NA which are DIP
also for C215-218 try using the Nichicon HE variants, as they are lower impedance then the PW
I am also going to replace the 10k 120v with 10k 100v (125v surge) as every amp I have measured seems to have the 95v rail at about 90v- depending on mains voltage
Another useful thing to do is to replace the 79M18 and 78M18 with new versions- I have done this on a number of preamps and it does appear to lower the residual noise
finally I am considering replacing C301-304 (4.7uf 100v) with larger caps to see if that makes an appreciable difference
hope this assists
Peter
Yes I did find COG ceramics and opted for KEMET -80-C330C103J5G for C111-114.
well spotted typo- yes replaced these with 1000pf WIMA
The OPamps- yes the LME49860 are now surface mount only- so I will now be using LME49720NA which are DIP
also for C215-218 try using the Nichicon HE variants, as they are lower impedance then the PW
I am also going to replace the 10k 120v with 10k 100v (125v surge) as every amp I have measured seems to have the 95v rail at about 90v- depending on mains voltage
Another useful thing to do is to replace the 79M18 and 78M18 with new versions- I have done this on a number of preamps and it does appear to lower the residual noise
finally I am considering replacing C301-304 (4.7uf 100v) with larger caps to see if that makes an appreciable difference
hope this assists
Peter
bill114
Active Member
I recently got a super clean 2600A to replace a 2400 as my main amp. It did need the relay replacement - these drop in. A couple of the mounting holes need to be enlarged slightly. I did it with a drill and small drill bit (carefully!)
http://www.newark.com/imo-precision-controls/srku-1ct-sl-24vdc/relay-automotive-spdt-14vdc-45a/dp/74R1551?ost=SRKU-1CT-SL-24VDC&ddkey=http:en-US/Element14_US/search
You'll need to change the relay coil load resistor as the new relay coil resistance is different from the original. As I recall you'll need a 240 ohm 2w resistor.
Here's a you tube video for the same repair on a 2200 which, from what I can see is the same amp without level controls.
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teal'c
Nuclear Cardiac Parent
bill114
Active Member
Looking at the data sheet for the LME49720NA, I noticed the supply voltage is listed as +/-17v. The schematic lists the supply voltage for the IC as +/-18v. Any issues here?
Would you be so kind to list me the capacitor brand and value upgrades for 1155 as well?
No particular brands. I just used whatever components I had to hand. As long as they are good quality it doesn't matter. What matters is the type of cap. Polycarbonate caps aren't available any more so use polypropylene. Polystyrene are hard to find these days (because of surface mounting) so use polypropylene instead.
Audiobro
Active Member
I just acquired a 2600 myself and have begun scouting out sources for caps. I have already run into a snag finding replacements for C411 and C412, these are 10000uf 120v. It looks like they are filtering 95v. Just wondering if anyone either knows if 100v will be a good replacement.
Finally found a forum about the 2200. My 2200PE has a DC thump when I shut the unit off...doesn't matter how I shut it off, via the power button or pulling the plug. It is on both sides.
What I did find interesting is that neither C415/416 (which are the 100V 0.1uf filter caps across the speak outputs) are factory installed. Could that be why I'm getting the thump? I was going to install the caps as listed on their service manual but in the mean time, I installed a switch to essentially turn off the speakers before I turn off the unit. I already replaced the protection relays due to loss of sound...
What I did find interesting is that neither C415/416 (which are the 100V 0.1uf filter caps across the speak outputs) are factory installed. Could that be why I'm getting the thump? I was going to install the caps as listed on their service manual but in the mean time, I installed a switch to essentially turn off the speakers before I turn off the unit. I already replaced the protection relays due to loss of sound...
I installed the caps...didn't help.
I did some more measuring and discovered a 75Vdc spike when I turn the unit off which makes my speakers thump/pop...where can I be getting a DC voltage from?
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Hi mohare
I am guessing the voltage comes form the power supply. Try measuring the output of the main amp boards and see if it is there, if so then measure the output of the input PCB and see if it is there as well- this will help diagnose where the spike is originating from. The other place to consider is the power switch
Peter
I am guessing the voltage comes form the power supply. Try measuring the output of the main amp boards and see if it is there, if so then measure the output of the input PCB and see if it is there as well- this will help diagnose where the spike is originating from. The other place to consider is the power switch
Peter
Hi
the 100v 125v surge SMH range form Nippon Chemicon work very well- they have additional pins, but small holes drilled in the PCB accomodate these for a tight and robust fit
mouser part number 661-EKSMH101VND103MA6
Peter
The schematic shows a protection relay. A thump may be caused by a slow release of the relay, maybe due to aged components.
The relay contacts can, over time, be permanently welded together or to a lesser extent "sticky" so the contacts don't release
at power down.
Suggest replace the speaker relay.
Thumps can be caused by an inbalance between the positive and negative power rails during powering down, one side decays
quicker than the other. A 75Vdc spike suggests one side has virtually turned off while the other is still charged, point being there
may be a problem.
First step, replace the relay, you could try measuring the resistance between the audio IN/OUT (amp powered off...)
Did thump occur on both channels?
Do not power down with speakers connected, your only doing damage...
@mbz you were right-on...though it wasn't the speaker relays (because I had already replaced those and it didn't help). It was the speaker protection IC (TA7317P). The voltages were off on a few of the pins. Long story short, the IC wasn't releasing the coils fast enough during power off (about a 1/2 second delay) and the thump would occur. I replaced the IC ($5) and now it works perfectly!
Also, to answer your question, the thump was on both channels, which led me to believe it had to be a common circuit on the unit considering there are completely independent signal/amplification paths on these units.
Also, to answer your question, the thump was on both channels, which led me to believe it had to be a common circuit on the unit considering there are completely independent signal/amplification paths on these units.
bill114
Active Member
Hey mohare
I'm wondering where you found the values of the voltages that should be present at the IC pins. The issue I'm having is with a 2400 which is similar.
I have the schematic but there's no voltage values on it