My electronic knowledge is limited so this might be a basic question ...
The attached section of circuit diagram is one channel of the output stage of a NAD 5420 CDP.
Q202 and Q204 are both NE5532 dual opamps but as you can see Q202 is using only pins 5,6 & 7 while Q204 is using pins 1,2,3, 4 & 8.
It appears to me that only half of each of these dual opamps is being used. Is this correct?
Secondly, Q202 appears not to be using the V+ & V- power supply connections. Are they omitted by convention or if not, what's the role of this opamp?
I ask these questions because I had been planning to replace the NE5532 opamps in my CDP with a set of Burson's discrete component dual opamps but it doesn't look logical to just replace both [or all 4] of the NE5532s with 4 x dual Burson opamps.
parrot
The attached section of circuit diagram is one channel of the output stage of a NAD 5420 CDP.
Q202 and Q204 are both NE5532 dual opamps but as you can see Q202 is using only pins 5,6 & 7 while Q204 is using pins 1,2,3, 4 & 8.
It appears to me that only half of each of these dual opamps is being used. Is this correct?
Secondly, Q202 appears not to be using the V+ & V- power supply connections. Are they omitted by convention or if not, what's the role of this opamp?
I ask these questions because I had been planning to replace the NE5532 opamps in my CDP with a set of Burson's discrete component dual opamps but it doesn't look logical to just replace both [or all 4] of the NE5532s with 4 x dual Burson opamps.
parrot
Attachments
parrot said:Yes, there's logic behind that suggestion but the other side uses a completely separate pair and that's clear from the full circuit diagram [as well as by looking inside the box ].
parrot
Really? Can you post a complete schematic of all the audio stages and/or the PCB track layout. I can't believe that half of dual opamp part would be wasted in a commercial design, when a single opamp part could be used.
parrot said:
If it is as it appears to be, what's happening with opamps Q201 & Q202, which don't seem to have a power supply?
Q202 and Q204 are both in the same chip ( the dual NE5532), so pin 4 an 8 are the supply pins common to both channels.
The same happens with Q201/203.
In any doubt, consult the NE5532 data sheet...
parrot said:
I've checked the data sheet, the complete parts list and looked in the box and there are four [4] chips.
parrot
4 chips, because there are 2 for each channel, but what I have told you in my previous post ( #11 ), totally apply ...
Going crosseyed looking at that . They are 5532,s not 5534 in the player. Pin 5 does not look connected on the layout.
Edit, If they are 5532 then there are 8 individual OpAmps in there, the filter for the player shows 4. So how are they connected. The image is not really clear enough.
Edit, If they are 5532 then there are 8 individual OpAmps in there, the filter for the player shows 4. So how are they connected. The image is not really clear enough.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
- Home
- Amplifiers
- Chip Amps
- NAD 5420 CDP opamps