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Buckeye Amps: New US based Hypex multichannel amplifier builder, line-up announcement!

nstzya

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I'm using the Magnius for 2 purposes: (1) proper unbalanced to balanced conversion, and (2) set the "max volume."

I set an arbitrary max volume on the Magnius (based on wife and dog acceptance criteria) and leave it alone. I then use the Blue OS SW volume control to manage the volume below that preset maximum.

I decided to use the "Low Gain" setting on the Magnius. I experimented with both High/Low and felt that the added granularity (greater ability to fine tune the potentiometer setting) was meaningful. And, with the gain set on "High Gain," not only is it loud AF, it adds unnecessary risk when the wife occasionally decides to take matters (the volume knob) into her own hands.


Oh, I assumed that you used the preamp due to the relatively low sensitivity of the 502. Since the Bluesound as well as the Topping both max out at 2V and the sensitivity of the 502 is 2.38V (meaning that you need 2.38V to get max output from the amp), if you don't preamp you are not within the amps power envelope and not getting max performance or output.

The 502's have an input sensitivity of 2.35v and the 252's 1.66v

Why IS the 502 sensitivity so much lower than the 252's?
 

NTK

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Why IS the 502 sensitivity so much lower than the 252's?
The NC MP series amplifiers all have the same gain, which means, regardless of which model, when they are supplied the same input signal voltage, you'll get the same SPL if you use the same speakers. This is sometimes desirable for multi-channel use. Therefore, since the 502 is capable of higher maximum output, it will require a higher level input to drive it to maximum output.
 

Jdunk54nl

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The NC MP series amplifiers all have the same gain, which means, regardless of which model, when they are supplied the same input signal voltage, you'll get the same SPL if you use the same speakers. This is sometimes desirable for multi-channel use. Therefore, since the 502 is capable of higher maximum output, it will require a higher level input to drive it to maximum output.

So with that info, most people with AVR's that are buying these for multi channel, would actually be better off with the 252mp, since most max their clean output voltage around the 1.4v mark.

Unless you have a way upping the voltage out of your AVR before it gets to the amp.


Granted, a benefit for the 502 amps would be headroom, but that would never be reached with most avr's with their max clean output.
 

AdamG

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The NC MP series amplifiers all have the same gain, which means, regardless of which model, when they are supplied the same input signal voltage, you'll get the same SPL if you use the same speakers. This is sometimes desirable for multi-channel use. Therefore, since the 502 is capable of higher maximum output, it will require a higher level input to drive it to maximum output.

Excuse my lack of understanding here. I have a Denon 8500h and just hooked it up to the Buckeye 502. How do I discover if I have a gain match problem? I am also using an XPA-5. In total I have 9 channels driven by amps (4) on the XPA and (5) on the 502. Leaving the 3 height channels (6) being powered by the Denon. I did use the Custom amp assignment and set all AVR channels to None for all the Bed speakers.

This gets very confusing as I read different answers in different forms. I have learned to trust answers from this forum more than other sources. Thank you kindly for any assistance in clarifying this concern.
 

nstzya

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The NC MP series amplifiers all have the same gain, which means, regardless of which model, when they are supplied the same input signal voltage, you'll get the same SPL if you use the same speakers. This is sometimes desirable for multi-channel use. Therefore, since the 502 is capable of higher maximum output, it will require a higher level input to drive it to maximum output.

In addition to being able to achieve maximal output (otherwise you might just as well have bought a 252), isn’t it important to be above the amplifier sensitivity to keep S/N optimal?
 

NTK

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Excuse my lack of understanding here. I have a Denon 8500h and just hooked it up to the Buckeye 502. How do I discover if I have a gain match problem? I am also using an XPA-5. In total I have 9 channels driven by amps (4) on the XPA and (5) on the 502. Leaving the 3 height channels (6) being powered by the Denon. I did use the Custom amp assignment and set all AVR channels to None for all the Bed speakers.

This gets very confusing as I read different answers in different forms. I have learned to trust answers from this forum more than other sources. Thank you kindly for any assistance in clarifying this concern.
The NC502, for 4Ω loads, requires an input of 2.35 Vrms to drive to its rated output of 500 W. For 8Ω loads, it requires 2.7 Vrms to its rated output of 350 W.

Amir has tested the 8500H, and it has no problem putting out the standard single ended output level of 2 Vrms (which is what Denon's spec for its DAC output level). So, at worst, you can get 355 W @ 4Ω and 177 W @ 8Ω with your setup. (Your Emotiva has an input sensitivity of 1.5 Vrms, and thus is not a problem.)

I understanding this is far from ideal. The 25.5 dB gain of the Hypex NC MP is a bit low when driven by single ended inputs. The THX standard asks for 29 dB. Sorry.
 

NTK

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In addition to being able to achieve maximal output (otherwise you might just as well have bought a 252), isn’t it important to be above the amplifier sensitivity to keep S/N optimal?
The optimal is for the power amp to just have enough gain to drive to full output. More gain will reduce the S/N ratio, theoretically. But with a rated S/N ratio of 124 dB for the NC502, IMHO, sacrificing a few dB in SNR to get a few more dB in gain is a worthwhile tradeoff.
 

AdamG

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The NC502, for 4Ω loads, requires an input of 2.35 Vrms to drive to its rated output of 500 W. For 8Ω loads, it requires 2.7 Vrms to its rated output of 350 W.

Amir has tested the 8500H, and it has no problem putting out the standard single ended output level of 2 Vrms (which is what Denon's spec for its DAC output level). So, at worst, you can get 355 W @ 4Ω and 177 W @ 8Ω with your setup. (Your Emotiva has an input sensitivity of 1.5 Vrms, and thus is not a problem.)

I understanding this is far from ideal. The 25.5 dB gain of the Hypex NC MP is a bit low when driven by single ended inputs. The THX standard asks for 29 dB. Sorry.

Thank you very much for the reply and data. Not good news since I picked the 502 to drive ml 4ohm speakers. Is there any fix or solution that would help?

So the 502 ratings of 350w@8ohms and 500w@4ohm has been reduced to 177w and 355w respectively?
 
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NTK

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Thank you very much for the reply and data. Not good news since I picked the 502 to drive ml 4ohm speakers. Is there any fix or solution that would help?
You need to add just a little bit of gain in between the 8500H and the NC502. You can use headphone amps (e.g. JDS Labs Atom or Schiit Asgard or the many equivalents) for that purpose.

[Edit] Or you can just ignore this problem. I don't think it would be very noticeable.

[Edit]
So the 502 ratings of 350w@8ohms and 500w@4ohm has been reduced to 177w and 355w respectively?
Yes. It would be a 3 dB and 1.5 dB reduction in max SPL, respectively.
 
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amper42

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Thank you very much for the reply and data. Not good news since I picked the 502 to drive ml 4ohm speakers. Is there any fix or solution that would help?

So the 502 ratings of 350w@8ohms and 500w@4ohm has been reduced to 177w and 355w respectively?

If you are using an external amp with the Denon receiver for home theatre, I would suggest selecting an amp with 28-29dB gain. I found when I used my March P452 Purifi based stereo amplifier (26.5dB gain) that it would drive speakers significantly softer than speakers connected to my Monolith 7x200 amp. Audyssey was unable to properly match the volumes at all levels.

Either use pre-amp mode and all external amps from the same model/brand or go with amps in the 28-29db gain range. While the lower gain amps will work, they likely will not offer a good match with other higher gain amps at all levels in a Denon home theatre setup.
 

nstzya

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The optimal is for the power amp to just have enough gain to drive to full output. More gain will reduce the S/N ratio, theoretically. But with a rated S/N ratio of 124 dB for the NC502, IMHO, sacrificing a few dB in SNR to get a few more dB in gain is a worthwhile tradeoff.

To help illustrate and clarify, lets use the figures for the 502. Are you saying that a 2.7V input would be optimal?
 

NTK

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To help illustrate and clarify, lets use the figures for the 502. Are you saying that a 2.7V input would be optimal?
Yes. That would be theoretically optimal, but in real life it would be difficult to achieve a perfect match.

Please note that we are talking maximum output levels here. In 99.99+% of the time we should have less than 2.7 V input.
 

nstzya

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How about more than 2.7V? If one were to interject a headphone preamp to boost the 2V output, is there such thing as TOO much boost? 3V? 4V? (I realize that one would obviously then need to turn down the volume from the source).
 

NTK

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How about more than 2.7V? If one were to interject a headphone preamp to boost the 2V output, is there such thing as TOO much boost? 3V? 4V? (I realize that one would obviously then need to turn down the volume from the source).
Your last sentence (in parentheses) basically answered your question.

If we listen at a certain SPL, the power amp will output the same voltage (and current, since they are governed by Ohm's law). If the power amp has a fixed gain like the NC MP series, the input voltage to the power amp must remain the same. That means the DAC or preamp will output the same voltage to the power amp.

Now what if we have a really high max output preamp? Well, you'll just dial down the volume knob to reduce the preamp output voltage. There isn't that much downside to having a source that can give a higher than necessary output. The same can be said that there isn't a huge downside to having a power amp with a higher gain. (Of course this cannot be taken to extremes. Too much gain hurts S/N ratio.) In the old(er) days, sensitivities for power amps were usually about 1 V. The recent trend is to reduce the power amp gains (and therefore sensitivities) to boost the S/N ratio to win the specmanship war.
 

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You need to add just a little bit of gain in between the 8500H and the NC502. You can use headphone amps (e.g. JDS Labs Atom or Schiit Asgard or the many equivalents) for that purpose.

[Edit] Or you can just ignore this problem. I don't think it would be very noticeable.

[Edit]

Yes. It would be a 3 dB and 1.5 dB reduction in max SPL, respectively.

Hi NTK,

Firstly thank you so very much for sharing your incredible knowledge and time with us. Quite generous of you Sir.

I have a follow up question. The Denon 8500h uses Audyssey to level match each channel individually. How will this process affect this gain disparity, will it make it better, worse or no change?

Second part, the 8500 gives the user the ability to manually tweak each individual output channel gain setup after and before Audyssey Calibration. Following your calculated net 3 db deficit, could I use this adjustment to boost each individual channel powered by the Hypex by +3.0db to overcome this gain imbalance ?

I realize I may be grasping for straws here. Again, very much appreciate what you have added to the conversation.
 

nstzya

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Now to help me understand this whole sensitivity issue just a bit further. When we talk of an input of 2V being inadequate to drive an amplifier with 2.7V sensitivity to full power, etc... are we talking 2V RMS or 2V peak? If the DAC or Node 2i puts out greater than 2.7V peak, shouldn't that be enough? They are rated 2-2.1V RMS but put out near 3V peak. Or is sensitivity spec'd RMS?
 

NTK

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Hi NTK,

Firstly thank you so very much for sharing your incredible knowledge and time with us. Quite generous of you Sir.

I have a follow up question. The Denon 8500h uses Audyssey to level match each channel individually. How will this process affect this gain disparity, will it make it better, worse or no change?

Second part, the 8500 gives the user the ability to manually tweak each individual output channel gain setup after and before Audyssey Calibration. Following your calculated net 3 db deficit, could I use this adjustment to boost each individual channel powered by the Hypex by +3.0db to overcome this gain imbalance ?

I realize I may be grasping for straws here. Again, very much appreciate what you have added to the conversation.
I have no experience with Audyssey and don't know the details of how it works, so what I'm going to say is all conjecture.

Hypex's engineering decision to keep the same gain across the NC MP line, IMHO, isn't really that necessary. Most people with HT setups will have different speakers for their L&R, C, and surrounds (and heights). These speakers will have different sensitivities. So this already makes having the same amplifier gain quite worthless.

I guess what Audyssey would do in level matching is to pick the speaker that is softest during its measurement, and assign it with the highest gain. All other channel will have lower gains. The reason is that if the 8500H output to the softest speaker is not maxed out, the other ones won't. [In digital, the maximum output is well defined -- it is 1.0 (i.e. full scale in floating point numbers). Therefore the absolute max output level, regardless of which music or movie you are going to play, is also known in advance -- they cannot exceed 1.0.]

The max output level from your 8500H, assuming Denon gives no margin above its spec, is 2 Vrms. Manually changing the gain in Audyssey, I'd think, is not going to increase the max output voltage. Depending on how it is implemented in Audyssey, it may just result in digital clipping.
 

NTK

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Now to help me understand this whole sensitivity issue just a bit further. When we talk of an input of 2V being inadequate to drive an amplifier with 2.7V sensitivity to full power, etc... are we talking 2V RMS or 2V peak? If the DAC or Node 2i puts out greater than 2.7V peak, shouldn't that be enough? They are rated 2-2.1V RMS but put out near 3V peak. Or is sensitivity spec'd RMS?
The voltage spec is RMS. Or more specifically, Vrms of a single frequency sine wave, which is equal to Vpeak / sqrt(2).
 
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