You could simply use two resistors per channel on the input as a voltage divider, but I have modified my nC400s to lower the gain by increasing the feedback - increasing the feedback theoretically also improves performance slightly. See https://www.hypex.nl/img/upload/doc/an_wp/AN_Voltage_gain_hypex_modules.pdf
1. 26 dB of gain is normal for a power amplifier, the Benchmark is actually the outlier in this regard (and its low gain is partially responsible for its somewhat misleading specs)...
2. At 26 dB, the amplifier will reach about 200 watts output into a typical 8 ohm load with a 2 volt input: so if one wants to be able to use all of the available power, and has a typical source with a 2 volt output source, the gain of 26 dB is just about right.
So these amps are not unusual or high gain in any way, they are about standard. If you only need around 1/4 of their available power, it sounds like your speakers are likely very efficient, or you do not play music anywhere near realistic levels.
you have a few options to lower the gain of the system with one of these amps:
Are you purchasing from a retailer like Nord? If so, they may be able to lower the gain of their input buffer for you, as it is based on opamps, this probably is simply done by the changing of a couple of resistors per channel, I would ask them about this, as this would probably be the best way (for performance) as lowering the gain in the input buffer might also lower the noise floor a bit.
Or, you could just attenuate the signal with some in line attenuators right at the amplifiers input: try a Google search for inline attenuators. These would just be a resistor pad placed at the amplifiers input.
2. At 26 dB, the amplifier will reach about 200 watts output into a typical 8 ohm load with a 2 volt input: so if one wants to be able to use all of the available power, and has a typical source with a 2 volt output source, the gain of 26 dB is just about right.
So these amps are not unusual or high gain in any way, they are about standard. If you only need around 1/4 of their available power, it sounds like your speakers are likely very efficient, or you do not play music anywhere near realistic levels.
you have a few options to lower the gain of the system with one of these amps:
Are you purchasing from a retailer like Nord? If so, they may be able to lower the gain of their input buffer for you, as it is based on opamps, this probably is simply done by the changing of a couple of resistors per channel, I would ask them about this, as this would probably be the best way (for performance) as lowering the gain in the input buffer might also lower the noise floor a bit.
Or, you could just attenuate the signal with some in line attenuators right at the amplifiers input: try a Google search for inline attenuators. These would just be a resistor pad placed at the amplifiers input.
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1/4 of the power is only 6 dB lower than full power.
See https://www.hypex.nl/img/upload/doc/an_wp/AN_Voltage_gain_hypex_modules.pdf that I posted above.
Hi - a big thanks to everyone who replied to my question.
You all confirmed that the gain of these amps is nothing unusual. Yet the problem is there - my speakers have 89db sensitivity IIRC - so yes, for such speakers the amp is too powerful or gain just too high.
You all confirmed that I can either use attenuators or request the vendor to lower the gain of the input buffer.
I will try out the inline attenuators as a first measure and contact the vendor once I know exactly the values I need or want. It is good that this will only require a new set of custom input buffers that I can probably easily then exchange myself. So not a big change to the amp after all.
I thank you all immensely!
limao
You all confirmed that the gain of these amps is nothing unusual. Yet the problem is there - my speakers have 89db sensitivity IIRC - so yes, for such speakers the amp is too powerful or gain just too high.
You all confirmed that I can either use attenuators or request the vendor to lower the gain of the input buffer.
I will try out the inline attenuators as a first measure and contact the vendor once I know exactly the values I need or want. It is good that this will only require a new set of custom input buffers that I can probably easily then exchange myself. So not a big change to the amp after all.
I thank you all immensely!
limao
One user wrote
"Most of the nc500’s buffers are questionable but may suit your preference"
May I ask why these would be questionable?
Isn't the input buffer specifically there to give the Hypex a custom sound?
The input buffers from Apollon and Nord seem quite similar, use the same opamps. Are these not good?
"Most of the nc500’s buffers are questionable but may suit your preference"
May I ask why these would be questionable?
Isn't the input buffer specifically there to give the Hypex a custom sound?
The input buffers from Apollon and Nord seem quite similar, use the same opamps. Are these not good?
I have a need for a powerful amp with a low distortion and a high damping factor. 2 ohm load. I've been in looking in to the Nord One SE NC1200DM Stereo Amp
Nord One SE NC1200DM Stereo Amp | nordacoustics
and the Apollon Audio NC1200SL
Hypex NC1200 Based Class D Amplifier Apollon Audio NC1200SL | Hypex Based Class D Digital Handbuilt Amplifiers Only Using Highest Quality Material
Both are of course based on the Hypex NC1200.
For similar power and sound quality, what other options do I have in a price range of 2 - 5k€?
I noticed these amps don't seem to have any cooling fans, how quickly will they overheat, when you drive them hard?
Nord One SE NC1200DM Stereo Amp | nordacoustics
and the Apollon Audio NC1200SL
Hypex NC1200 Based Class D Amplifier Apollon Audio NC1200SL | Hypex Based Class D Digital Handbuilt Amplifiers Only Using Highest Quality Material
Both are of course based on the Hypex NC1200.
For similar power and sound quality, what other options do I have in a price range of 2 - 5k€?
I noticed these amps don't seem to have any cooling fans, how quickly will they overheat, when you drive them hard?
I don't know if I'm breaking any rules by mentioning this, but the amp in the link below will be ready for sales within some weeks. While it's based on NC500 and not NC1200, it does offer bridging option with more than 1200W in 8 ohm and has temperature controlled cooling fans. Measurements and more info will be published.
| Vera Audio |
Last time I checked, the Apollon web site listed a pair of NC1200 monoblocks with the new Premium cases and linear power supplies for the buffer and comparator. They are B-Stock as they have been used as demos, but they only have small scratches at the bottom, nothing otherwise visible once placed on a surface (if I have understood correctly). They are already burned in (of course) and discounted. Those should sound even better than normal NC1200 monos.
Roberto
Roberto
Hypex NC1200: Quality of the implementations | Audio Science Review (ASR) Forum
In the EU, Apollon, Rouge Audio and atm I do not like Nord stereo implementations of Hypex modules.
I did not know about Vera Audio, I take note. Inside pictures? Only a drawing, of NC500. Buffer boards? Without wiring.
| Vera Audio |
In the EU, Apollon, Rouge Audio and atm I do not like Nord stereo implementations of Hypex modules.
I did not know about Vera Audio, I take note. Inside pictures? Only a drawing, of NC500. Buffer boards? Without wiring.
| Vera Audio |
An externally hosted image should be here but it was not working when we last tested it.
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Oh yes, I didn't notice the Rouge Audio Alauda from Italy
ALAUDA DM-1200 | rougeaudiodesign
Thanks, but I would rather have one amplifier than two. However, it's nice that it has the fans. My experience is that they are usually needed, even with 90% efficiency. Only very big heat sinks would remove the need for those.
ALAUDA DM-1200 | rougeaudiodesign
Thanks, but I would rather have one amplifier than two. However, it's nice that it has the fans. My experience is that they are usually needed, even with 90% efficiency. Only very big heat sinks would remove the need for those.
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I think you guys are getting the wrong idea about the alternative input buffer boards for NC500. They are not using these to colour or create a house sound. The Hypex stock chip based op amp buffer certainly has a sound. The input boards from Hypex/Apollon use discrete op amps that are way more transparent. I use Sparko's versions in my bass amps for deeper bass and richer lower mids and Sonic Imagery versions in my Mid/Twt amps for detail and less forward top end. This is how they perform in my set up YMMV. I have also tried Burson V5, V6Vivid and V6Classic discrete devices. They all sound different, but are all better than the cheap and cheerful LM4562 in terms of improved detail and transparency. This is the goal of Nord/Apollon and the latest rev D boards from Nord take this a stage further using larger format discrete op amps normally found in studio gear. Not tried these yet, but there is a comparison of the two types on offer on hifi pig and I shall be upgrading my bass amps to the new Sparko's at some point for the "absolutely astonishing" bass. 
Nord NC500 Rev-D Input Buffer Board Upgrade | Hifi Pig
Nord NC500 Rev-D Input Buffer Board Upgrade | Hifi PigI think you guys are getting the wrong idea about the alternative input buffer boards for NC500. They are not using these to colour or create a house sound. The Hypex stock chip based op amp buffer certainly has a sound. The input boards from Hypex/Apollon use discrete op amps that are way more transparent. I use Sparko's versions in my bass amps for deeper bass and richer lower mids and Sonic Imagery versions in my Mid/Twt amps for detail and less forward top end. This is how they perform in my set up YMMV. I have also tried Burson V5, V6Vivid and V6Classic discrete devices. They all sound different, but are all better than the cheap and cheerful LM4562 in terms of improved detail and transparency. This is the goal of Nord/Apollon and the latest rev D boards from Nord take this a stage further using larger format discrete op amps normally found in studio gear. Not tried these yet, but there is a comparison of the two types on offer on hifi pig and I shall be upgrading my bass amps to the new Sparko's at some point for the "absolutely astonishing" bass.
Interesting. How do the Apollon discrete opamps compare to the discrete opamp circuitry of the nC400? What studio gear uses the "larger format discrete op amps" Nord uses?
I am using Nord, I think but am not certain, that Nord and Apollon used the same designer for their input buffer boards. They are similar size, have similar but not identical layout, use the same Sparko discrete regulators and have the same options of discrete op amps, from Sparko and Sonic Imagery available. I didn't think the op amps on the 400's were interchangeable and were LM4562 soldered to the board. Apollon offer the same op amp choices as Nord, including the Pro versions. Apollon also offer "Purifi" class D models as well as Hypex and Ice. Bruno Putzeys designed UcD and Ncore for Hypex, Purifi is his own company and these boards will be available to the DIY comunity. They measure very well according to Amir at ASR. The pin out on pro gear tends to be on the API footprint not dip 8, there is a list of compatible Pro gear for the Sparko Pro op amp here: Pro Discrete Op Amp - SparkoS Labs Inc.
They are indeed not interchangeable, but definitely not LM4562s - they are a discrete Hypex design.
Compatible means they can use sparko ones, but I am more curious to see a list of gear that actually uses them.
You'd have to trawl through the specs to find which, but the fact that they will fit means the gear is using API footprint so has something like it in there.
Checked the spec sheet, your right about NC400 having a discrete op amp, it must be part of the board SMD's as I can not see a stand alone device. The UcD was a soldered chip for sure.
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