Difference between different Hypex NCore models and input buffers?

[Koeitje]

So I've come to the conclusion that I want to buy a Hypex NCore amplifier somewhere this year, but the difference between models is driving me nuts. There are so many options out there.

What I've gathered so far is that the NC400 DIY kit is probably the best performing one of the bunch. I'm also looking at the NC500's, but I think there are mono and stereo (502?) boards. Seems that a stereo board wouldn't be as great and I would also prefer mono blocks.

Apart from the amplifier board there also seem to be a difference in input buffers. What do these do? My gut feeling says the standard Hypex one is probably one of the best anyway.

 

[March Audio]

There are a number of fancy buffers out there but nothing I have seen actually beats the performance of the top end op amps from the likes of TI. In fact some "discrete" buffers have quite poor performance. They all cost significantly more.

This is why March Audio doesn't indulge in this sort of marketing.

There are several threads here where Amir has tested swapping various op amps and buffers for esoteric ones if you want to know more.

However I note your comment about the standard Nc500 buffer from Hypex. Unfortunately that evaluation buffer from Hyoex is not recommended, as it is not what I call a "finished" circuit suitable for a final product. It's open wide bandwidth could cause problems.

As a general comment I would choose Purifi over the NC400.

 

[Koeitje]

Thanks forn

There are a number of fancy buffers out there but nothing I have seen actually beats the performance of the top end op amps from the likes of TI. In fact some "discrete" buffers have quite poor performance. They all cost significantly more.

This is why March Audio doesn't indulge in this sort of marketing.

There are several threads here where Amir has tested swapping various op amps and buffers for esoteric ones if you want to know more.

However I note your comment about the standard Nc500 buffer from Hypex. Unfortunately that evaluation buffer from Hyoex is not recommended, as it is not what I call a "finished" circuit suitable for a final product. It's open wide bandwidth could cause problems.

As a general comment I would choose Purifi over the NC400.

Thanks for the reply, but it seems like a Purifi setup would cost considerably more.

Can you also explain what these buffers do?

 

[dwkdnvr]

Thanks forn

Thanks for the reply, but it seems like a Purifi setup would cost considerably more.

Can you also explain what these buffers do?

A Purifi setup shouldn't be too much more than an NC400 build if you're going the DIY route, at least in the US. About $700 for the Purifi Eval kit, and ~$200 for the Hypex power supply. this is about $100 more than a stereo NC400 build, but less than NC400 monoblocks. This obviously assumes that the cost for a case is equivalent between the 2.

 

[March Audio]

Thanks forn

Thanks for the reply, but it seems like a Purifi setup would cost considerably more.

Can you also explain what these buffers do?

The buffer is used for two purposes. Raising the voltage from the source up to a level high enough to drive the amplfier module and raising the input impedance (the module is quite low).

A third purpose is to use the module to deliberatly change the sound, but if done this probably goes hand in hand with dodgy technical performance. Personally I don't want an effects box. I don't want an amplifier to change the sound, just make it louder without change.

 

[March Audio]

Just to clarify the difference between the Hypex modules you refer to.

There are a number of mudules suffixed MP which have integrated power supplies and buffers (not changeable) available in mono and stereo. Several power levels available. These work very well but sit below the NC400 in absolute performance. Then there is also the Nc500 which is just a mono amp module. You need to add power supply and buffer.

 

[AnLaoJin]

There are a number of fancy buffers out there but nothing I have seen actually beats the performance of the top end op amps from the likes of TI. In fact some "discrete" buffers have quite poor performance. They all cost significantly more.

This is why March Audio doesn't indulge in this sort of marketing.

There are several threads here where Amir has tested swapping various op amps and buffers for esoteric ones if you want to know more.

However I note your comment about the standard Nc500 buffer from Hypex. Unfortunately that evaluation buffer from Hyoex is not recommended, as it is not what I call a "finished" circuit suitable for a final product. It's open wide bandwidth could cause problems.

As a general comment I would choose Purifi over the NC400.

That's right. In my opinion, you are as cost-effective as Vera audio. But Nord Apollo is a bit of a loser

 

[AnLaoJin]

Just to clarify the difference between the Hypex modules you refer to.

There are a number of mudules suffixed MP which have integrated power supplies and buffers (not changeable) available in mono and stereo. Several power levels available. These work very well but sit below the NC400 in absolute performance. Then there is also the Nc500 which is just a mono amp module. You need to add power supply and buffer.

The two of them are like assembly plants. They sell cheap things with gorgeous and impractical parts at high prices. They are profiteers

 

[Dave H]

The two of them are like assembly plants. They sell cheap things with gorgeous and impractical parts at high prices. They are profiteers

They are some of the best preforming and sounding amplifiers money can buy. I wouldn't consider them as profiteers at all, their price is very reasonable considering the power and performance available from these amps.

 

[Puska]

Audiophonics assembled Hypex NC400 mono blocks are excellent.

 

[formdissolve]

Is the stock Hypex NC500 OEM eval adapter really that bad? If it measures poorly enough to do an injustice to their amp boards, why even sell it? Would it be justifiable to get a Purifi kit with this buffer board, or would it be better to just bite the bullet and drop the extra $3-400 on other custom boards?

 

[March Audio]

Is the stock Hypex NC500 OEM eval adapter really that bad? If it measures poorly enough to do an injustice to their amp boards, why even sell it? Would it be justifiable to get a Purifi kit with this buffer board, or would it be better to just bite the bullet and drop the extra $3-400 on other custom boards?

It's is an evaluation board intended for use by designers that understand its design and limitations. It is not what I would call a finished design suitable for use in a product.

The problem is that it has no bandwidth limitation. There are no feedback caps and it's wide open. This can cause unpredictable performance and make it susceptible to issues such as general environmental RF and that coming out of dacs.

 

[formdissolve]

@March Audio makes sense now, I definitely read the briefing wrong. Thanks for the clarification.. I guess I'll have to spend a bit more now on better buffers!

 

[mrjktcvs]

The buffer is used for two purposes. Raising the voltage from the source up to a level high enough to drive the amplfier module and raising the input impedance (the module is quite low).

A third purpose is to use the module to deliberatly change the sound, but if done this probably goes hand in hand with dodgy technical performance. Personally I don't want an effects box. I don't want an amplifier to change the sound, just make it louder without change.

The input buffer's primary purpose is to present the optimal input impedance to your source

 

[March Audio]

The input buffer's primary purpose is to present the optimal input impedance to your source

Yes I said that.

.... And to raise the input signal level as any domestic standard source will not be high enough to drive the module to full output.

 

[john61ct]

Yes I said that.

.... And to raise the input signal level as any domestic standard source will not be high enough to drive the module to full output.

So can a buffer be dispensed with if an active preamp is used?

 

[March Audio]

So can a buffer be dispensed with if an active preamp is used?

If it's happy to drive a low impedance and can drive a high enough voltage, yes. However be aware the module would still lack input filtering so same caveats mentioned above apply.

 

[EB1000]

The buffer is used for two purposes. Raising the voltage from the source up to a level high enough to drive the amplfier module and raising the input impedance (the module is quite low).

A third purpose is to use the module to deliberatly change the sound, but if done this probably goes hand in hand with dodgy technical performance. Personally I don't want an effects box. I don't want an amplifier to change the sound, just make it louder without change.

Buffers by definition, do no raise the level. They only increase input impedance. The typical output impedance of a pre-amp is between 150 to 400 ohms. The typical input impedance of a class-d amp is about 7 to 12kOhms. Hence, no buffer is needed, as you won't lose more than a 0.25db

 

[March Audio]

Buffers by definition, do no raise the level. They only increase input impedance. The typical output impedance of a pre-amp is between 150 to 400 ohms. The typical input impedance of a class-d amp is about 7 to 12kOhms. Hence, no buffer is needed, as you won't lose more than a 0.25db

Oh FFS, pedantry .

An intermediate buffer amplifier IS required to raise the input voltage and input impedance for Hypex modules to a level suitable to drive them to full output with typical domestic level output DACs and pre-amps. Hypex even call it a "buffer".

NC500 module input impedance is 1.8 kohms. Hypex recommend no more than 50 ohms output Z from your source to achieve best performance. You also need to be careful without a buffer not to create inappropriate high pass filters if the source has output caps. You still require input filters for the module to avoid the possibility of intermodulation with the switching frequency and other negative effects.

The NC500 module on its own without an input buffer has a gain of 12.4dB. That would require an input of 12.7 volts rms to achieve full power output into 4 ohms.

 

[restorer-john]

The typical output impedance of a pre-amp is between 150 to 400 ohms. The typical input impedance of a class-d amp is about 7 to 12kOhms. Hence, no buffer is needed, as you won't lose more than a 0.25db

Typical HiFi preamplifiers have rated outputs (SE) of 1-1.5V for a 150mV input. Obviously, if you put in 2.0V you will swing some very high voltages out of the good ones. I've had preamps that would swing up to 35V prior to clipping and most in my collection will easily swing 10-15V, all with extremely low output impedances. My Accuphase is rated at 1 ohm on the SE (RCA) jacks and 600ohms (correct) on the balanced (300+300) and it will happily swing 12V RMS out the RCA jacks. But the volume pot is around a 3pm to do that.

The issue is "typical" domestic preamplifiers would be a poor match in terms of volume pot position/range with a 12.4dB gain power amp. The buffer IS required to bring these amplifiers to a more typical overall gain. It's not rocket science.