I am planning to drop Hypex NC500 modules into a dead Haffler amp, using its power supply, case, and connectors. What is the minimal hookup? Do pins 25, 26 (Vaux- and Vaux+) need to be connected to +/- 15V to operate the module or is this optional? Can/should pin 11 (VDR) be left unconnected? Does pin 32 (Enable) need to be connected to ground? Thanks in advance!
You should read the Hypex data sheet for the NC500. It will tell you that you will need a floating Vdr, a positive supply referenced to the -64 volts that you use. You will also likely need some sort of opamp based gain stage that will provide a balanced and low impedance source for the inputs along with some gain, I have used the Tom Christianson board which is very good though there are others available. You can design your own, again based on the info in the datasheet. One word of warning. Do not let the Vdr supply start before the -64 volt rail is up and running, or stop after it has dropped. It'll damage the module(s). I'm pretty sure the Vaux is needed, both for the NC500 module itself, and also for the gain stage. BTW you can supply Vaux from regulators/filtering off the +/-64v supply but quality will be better with a totally separate supply for +/- Vaux, just likethe one you will need for the floating +Vdr (referenced to -64v).
John
John
Thank you John.
What exactly is this Vdr and is it mandatory?
Are the other connections I have shown in the schematic correct? E.g., continuously tying the feedbacks (FBH and FBC) to their respective speaker outputs?
Yes I was thinking of having a separate +/-15V supply for the preamp/gain stage.
Do you know whether the two speaker outputs (hot and cold) are floating? I.e., the "cold" isn't or shouldn't be connected to ground?
Thanks again for your help.
Coco
What exactly is this Vdr and is it mandatory?
Are the other connections I have shown in the schematic correct? E.g., continuously tying the feedbacks (FBH and FBC) to their respective speaker outputs?
Yes I was thinking of having a separate +/-15V supply for the preamp/gain stage.
Do you know whether the two speaker outputs (hot and cold) are floating? I.e., the "cold" isn't or shouldn't be connected to ground?
Thanks again for your help.
Coco
Just wanted to add that the additional +/-15V supply for the preamp/gain stage can also be used for the +/- Vaux.
Hi Coco,
The Vdr is indeed mandatory if you want the amp to make a sound. Between the voltage it produces and the -64v line sits the main power switching device and its driver circuit. I've measured mine and it uses circa 70mA. Your connections look good to me but to show the Vdr inputs put the +V Vdr to pin 11 and its negative input to pin 9. You could try taking the Feedback inputs to the speaker connections later on when all is working. Section 4.4 of the Hypex NC500 OEM datasheet explains that the speaker cold output "OUTC" should not be connected to Ground, i.e. they must be floating. Finally, I have recently built this amp up in its own chassis and noticed progressive improvements as I have separated out each of the linear feeds and regulated them well. Of course this takes up a lot more space but IMHO is worth it.
It strikes me from your questions that you may not have access to the OEM datasheet. I wouldn't proceed without it so if you don't have it message me your email address and I'll email you a copy.
John
The Vdr is indeed mandatory if you want the amp to make a sound. Between the voltage it produces and the -64v line sits the main power switching device and its driver circuit. I've measured mine and it uses circa 70mA. Your connections look good to me but to show the Vdr inputs put the +V Vdr to pin 11 and its negative input to pin 9. You could try taking the Feedback inputs to the speaker connections later on when all is working. Section 4.4 of the Hypex NC500 OEM datasheet explains that the speaker cold output "OUTC" should not be connected to Ground, i.e. they must be floating. Finally, I have recently built this amp up in its own chassis and noticed progressive improvements as I have separated out each of the linear feeds and regulated them well. Of course this takes up a lot more space but IMHO is worth it.
It strikes me from your questions that you may not have access to the OEM datasheet. I wouldn't proceed without it so if you don't have it message me your email address and I'll email you a copy.
John
Thanks again John,
Sorry about all the dumb questions. Still confused about the Vdr. Where is this voltage coming from -- a signal from some protection circuit? If a protection signal is not required, can one simply connect a constant voltage (or short) between pins 9 and 11 to enable the module?
Yes, please do email me (cococola9@gmail.com) the datasheet (although I may have this) and information about the opamp based gain stage that you mentioned. I did get a link (https://www.hypex.nl/media/c4/13/51/1738587870/NC500_OEM_02xx R11.pdf)
to a datasheet from the Ebay seller (https://www.ebay.com/itm/387556828888). This might be the same document that you refer to. The board is labelled as an NC400 (please see picture), but its format and pinout is apparently the same as the NC500. This one also has a thermistor or some other kind of temperature sensor with 2 wires connecting to a 2-pin socket. The more recent NC400 looks quite different (circular) and has a buffer and gain built in. Hopefully the pair of NC500's I bought are not fake! I will know more if I test them.
Thanks and best regards,
Coco
Sorry about all the dumb questions. Still confused about the Vdr. Where is this voltage coming from -- a signal from some protection circuit? If a protection signal is not required, can one simply connect a constant voltage (or short) between pins 9 and 11 to enable the module?
Yes, please do email me (cococola9@gmail.com) the datasheet (although I may have this) and information about the opamp based gain stage that you mentioned. I did get a link (https://www.hypex.nl/media/c4/13/51/1738587870/NC500_OEM_02xx R11.pdf)
to a datasheet from the Ebay seller (https://www.ebay.com/itm/387556828888). This might be the same document that you refer to. The board is labelled as an NC400 (please see picture), but its format and pinout is apparently the same as the NC500. This one also has a thermistor or some other kind of temperature sensor with 2 wires connecting to a 2-pin socket. The more recent NC400 looks quite different (circular) and has a buffer and gain built in. Hopefully the pair of NC500's I bought are not fake! I will know more if I test them.
Thanks and best regards,
Coco
That's the NAD licensed module for the M22.
The VDR voltage is a separate 12v supply for a driverstage. -12v(0) to -64v and +12v to +VDR.
https://www.manualslib.com/manual/1332020/Nad-M22.html?page=13#manual
The VDR voltage is a separate 12v supply for a driverstage. -12v(0) to -64v and +12v to +VDR.
https://www.manualslib.com/manual/1332020/Nad-M22.html?page=13#manual
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Thanks. So this is a single floating 12V supply (not a -12V to 0 to +12V split supply), with its negative connected to HV- and its positive end connected to the Vdr+ input? I am fairly confident this will be my last question!
That is correct. Vdr must be a totally separate supply, but it must be between 14 and 17 volts (not 12v) on the NC500. It also must be applied after HV- on startup and cease before it on shutdown. I'm pretty sure that allowing Vdr to go positive with respect to 0v damaged one of my first modules. A regulator board with an enable pin such as for a Lt3042/5is ideal in this role. I recommend the LDOVR.com LT3045 regs for this with a voltage divider off HV- setting the threshold for switch on on its enable pin.
Looks like you already have the correct data sheets.
John
Looks like you already have the correct data sheets.
John