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NAD 216 THX - Make it sound better?
NAD 216 THX - Make it sound better?
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Old 10th August 2013, 10:46 PM   #11
ron1999 is offline ron1999  Israel
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Quote:
Originally Posted by Vrystaat View Post
Check this, Sakis gave me some info, he has seen this all. This is a great amp. Fix it, you will be a happy chappy. Nad 214 DC on output


thanks for the link - very useful information.
some expressions are not clear to me: (taken from the original link)

--- muting transistors in the input is something i disapprove and normally remove to all units - any chance to mark those on the schematics?
---Given the chance you may upgrade the main power banks to something bigger since the pcb may accommodate more but only thin and tall as far as i remember - i replaced two pairs of the original big caps (4700uF/80v) and replaced third pair with two 15000uF/100v
---Inspect IC 201 for soldering issues verify proper voltage there - just had it re soldered

---Input caps are also low quality .... some better and may be bigger cap there may be some improvement - any chance to mark those on the schematics?

---Tackle the protection relay to see for interrupt while in very low power mode if needed replace - how do i do that?

---Inspect input plugs often there you have soldering issues especially if input plugs/cables are big or heavy - inspected, they're fine

--last verify bias of the amplifier since the manufacturer of the amp ( depending on the serial number ) decided to decrease the bias on production to preserve some safety more while the designer on the service manual share some other opinion . Tune according to the schematic expect overall temperature to increase but just a bit .remember to warm up tune and verify more than once or twice if needed . - on my check list, will probably do it by end of tomorrow
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Old 11th August 2013, 06:28 AM   #12
Welcome is offline Welcome  France
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I think you imagined the improvement in sound, because they guy said he had improved it.

I think you are imagining another change now, that the guy said he turned it back to normal.

In reality, the amp most likely sounded exactly the same, all along. You can't make a few tweaks to improve the sound of an amplifier - you have to go with a different design altogether.
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Old 11th August 2013, 10:10 AM   #13
ron1999 is offline ron1999  Israel
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Quote:
Originally Posted by Welcome View Post
I think you imagined the improvement in sound, because they guy said he had improved it.

I think you are imagining another change now, that the guy said he turned it back to normal.

In reality, the amp most likely sounded exactly the same, all along. You can't make a few tweaks to improve the sound of an amplifier - you have to go with a different design altogether.
of course you can change the sound of an amp by performing a few tweaks, otherwise you'd be dropping the ground from under 99% of the discussions here
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Old 12th August 2013, 03:48 PM   #14
ron1999 is offline ron1999  Israel
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MAD 216 Inputs schematics
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File Type: jpg SP32-20130812-184533.jpg (177.1 KB, 388 views)
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Old 12th August 2013, 04:11 PM   #15
east electronics is offline east electronics  Greece
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Quote:
Originally Posted by JonSnell Electronic View Post
In "Stock" mode the response between 20 and 20kHZ is + or- 0.8DB worst case!
That is pretty flat so removing any filter/clipping/protection bits and pieces will make the amplifier non linear and possibly dangerous.
Can you be specific as to the difference in sound reproduction?
Any "Professional Engineer" that removes components or indeed changes the values without the authorisation by way of an official update from the manufacturer, requires re-training in my view.

Come on John this is so WRONG !!!

Removing filter/clipping/protection bits and pieces cannot and will not change the linearity of the amplifier .... On the other side one capacitor in the feedback chain will do that ( for example )

Removing filter/clipping/protection bits and pieces can and will change the safety margins of the amplifier ...only !

@ Ron
What you ask me to do is not easy since i have no idea what happened inside your amp anyway

As a generalization
--Higher capacitance on the power supply
--Higher capacitance on the secondary power supply better quality elkos there is a must
Bypass will also help in both stages need to be careful there and verify results with a scope
For the input stage :
Remove :
R101,R103,Q101,C103 R102,R104C102,Q102 these are the parts that mute the input Need to replace though C103-104 with 2.2ufd /63volt quite hard to find and i wouldn't recommend higher voltage than that ( exotic parts often behave as microphones due to physical size )
Then add 100pf in parallel with R105-106 do something like styroflex there anything but not ceramics
hardwire the input directly to C103 /104

Removing D101-103 and R109 110 will not only disable the soft clipping function but disconnect completely from the signal line

These are easy to do ... do it and listen and tell us what do you think ....

Kind regards
Sakis
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Last edited by east electronics; 12th August 2013 at 04:14 PM.
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Old 12th August 2013, 04:13 PM   #16
east electronics is offline east electronics  Greece
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as said in many other posts verify bias according to schematic in most of the cases is lower than designed or tuned wrong ( you may also try to increase it )
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Old 12th August 2013, 05:12 PM   #17
ron1999 is offline ron1999  Israel
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Sakis,
major thanks for the feedback

i will perfrom the changes tomorrow, after that i will re-calibrate bias and will listen to the amp again -
will be back for detail review of how that change sounds

BR


Ron.
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Old 13th August 2013, 06:04 PM   #18
ron1999 is offline ron1999  Israel
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ok,
so reports from today -
i check the bias -
it what pretty out of tune -
left was 22mV but right channel was 6mV
i tuned them both to 21mV (after i let the amp seat for 15 min while it was on)

but than the down side occur -
i tried to disconnect the soft clipping section:
i disconnected D101, D102, D103, D104 and also disconnected R109 and R110 (i did not took them out, but disconnect only one of the leg's each)

when i try to connect the amp again to check the bias - it will turn on now, but will only lit the red LED (like it has turned on, but will not come come out of protection or something)
should i expect this to happen?
did i get something wrong?
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Old 20th August 2013, 11:17 AM   #19
ron1999 is offline ron1999  Israel
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another update and further question:

1. working with bias level of 21mV led to a lot of heat while amplifier was on (practically -always) so bias rechecked and adjusted to 18mV

2. Any idea why removing the above components from the board caused the amp not to exit protection mode?
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Old 15th October 2017, 06:15 PM   #20
spiderman62 is offline spiderman62  Sweden
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I have bought recently a couple of this amps. 216 THX and open one of them for checking the caps since this is a simple way of making improvments. I was surprise to find out quite good Nichicon all the way on the power supply part of the amp.
I have measured them with quite good results. ERS = 0.11 and with good values close to what it should be originally. However I have found better caps (for replacing 4700 uF caps only) at Mouser electronics for incresing the capacitanse to 22 mF and decreasing ESR to. 0.03. No bad Elcos at all were found in these amps. Any one who knows if it was any improvement from early modells?
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