The AVP (D+M anyway..) that has the lowest THD+N measured so far seems to be a Denon AVR!!

[AcuDefTechGuy]

Here is Arcam’s response re: voltage, “First graphic – the ASR results are broadly correct in terms of distortion at these settings. ASR set the audio output to be 4V rms for a full scale digital input (0dBFS), so requiring a volume setting of 78, whereas the design output is intended to be less - around 2V rms – to match Arcam power amplifiers (volume 72 or 73). The AV40 uses a number of analogue multiplexers to route its signals internally and their distortion increases with signal level. There is a multiplexer on the L/R channels after the volume control and while this does not overload at 4V rms it does exhibit more distortion including a trace of high order harmonics. This is what he saw and in normal usage at around 2V maximum output this does not occur.”

I noticed that Arcam did not mention the difference in voltage between RCA vs XLR.

Are they saying that RCA and XLR have the same voltage in the Arcam?

Maybe @gene can elaborate as well since Gene talked about the 2V vs 4V in the Yamaha CX-A5200.

Maybe this preamp voltage varies depending on whether the unit has FULLY Balanced XLR vs Unbalanced XLR?

Most XLR's are Unbalanced. So perhaps only Truly Balanced XLR's have DOUBLE the Voltage as RCA and Unbalanced XLR's have the SAME voltage as the RCA?

Another thing I've noticed is that some amps have higher Gain for the XLR than for the RCA. For example, the Parasound A52+ UNBALANCED amp manual says the Volume for the XLR Input is 6dB HIGHER than the RCA Inputs.

However, on my FULLY BALANCED ATI amps (AT2005, AT3005), the RCA Input is actually LOUDER in volume than the XLR Input! The RCA has a Gain of 34dB and the XLR has a Gain of 28dB, also a Difference of 6dB, but the OPPOSITE of Parasound!

So the Parasound XLR is 6dB Louder than RCA, but the ATI RCA is 6dB Louder than XLR!

 

[HTNut1975]

I noticed that Arcam did not mention the difference in voltage between RCA vs XLR.

Are they saying that RCA and XLR have the same voltage in the Arcam?

Maybe @gene can elaborate as well since Gene talked about the 2V vs 4V in the Yamaha CX-A5200.

Maybe this preamp voltage varies depending on whether the unit has FULLY Balanced XLR vs Unbalanced XLR?

Most XLR's are Unbalanced. So perhaps only Truly Balanced XLR's have DOUBLE the Voltage as RCA and Unbalanced XLR's have the SAME voltage as the RCA?

I "think" that's what they're saying--either that or that the RCA is closer to 1V (which might make sense, since the JBL sister multichannel amp is rated at 800mV sensitivity (or something of the like).

I could email JBL support to find out (it was my unit that was tested). In the article I posted above (the review article discussing the AV860), it states that the output is consumer and not pro or something of the like. It gives me the impression that this architecture simply wasn't designed to do that (but what do I know?). I would love to hear Gene's feedback. Again, this is in no way a criticism of Amir or his testing methodology. I am just wondering whether to expect the same SINAD deficiency (as if I would be able to perceive it--I have my doubts). I'm also not entirely convinced that the Denon 8500 would perform any better driving my amp than the JBL with respect to SINAD. I have an NAD M28 and the spec sheet states that it is 1.3V sensitivity. Would that mean that it would require roughly 2.6 V to reach its maximum power on a balanced connection? If so, wouldn't that mean that this JBL processor wouldn't get close to 4 volts output?

 

[AcuDefTechGuy]

I "think" that's what they're saying--either that or that the RCA is closer to 1V (which might make sense, since the JBL sister multichannel amp is rated at 800mV sensitivity (or something of the like).

I could email JBL support to find out (it was my unit that was tested).

I would email JBL and ask if the Voltage is the SAME for both RCA and XLR outputs.

Ask them if RCA 2V = XLR 4V on the Arcam, or is the RCA 2V = XLR 2V on the Arcam.

 

[HTNut1975]

I would email JBL and ask if the Voltage is the SAME for both RCA and XLR outputs.

Ask them if RCA 2V = XLR 4V on the Arcam, or is the RCA 2V = XLR 2V on the Arcam.

Done! I’ll see what they say.

 

[PENG]

I attach the paper I refer to on this post.

I read that paper iirc someone linked it on ASR way back. Let's consider the following:

- The paper claimed the AV40 was rated 2 V XLR, their manual says 1 V unbalanced, 2 V balanced, so that's true.
- It also mentioned the output was designed to match their power amps, so I took downloaded the manual of their P49 power amp that is rated 200 W,, 8 Ohm, and the specs say:

Arcam - P49(Discontinued) - Power amplifier

Arcam’s P49 power amplifier represents the pinnacle of Arcam’s audio engineering. We set out to incorporate everything we have learnt i...

www.arcam.co.uk

"Continuous power output, per channel, 8Ω

• Both channels driven, 8Ω,20Hz-20kHz, 0.2% THD - 200W
• Single, 4Ω, at 1kHz - 400W

Inputs

• Nominal sensitivity for 200W / 8Ω - 1.15V (RCA), 2.3V (XLR)
• Input impedance - 10kΩ
• Frequency response 20Hz-20kHz +/- 0.05dB
• Signal/noise ratio (Awtd) 50W / 8Ω - 110dB"

So you can see that it is almost true, 2.3 V vs 2.0 V is 15%, but you can see that while it is almost true, that really wouldn't not allow any head room.

Denon, and Marantz, rated their pre-out 1.2 V, unbalanced of course, see specs below from the AV8805's manual. I used Marantz as example only because then you can see the unbalanced/balanced outputs:

So you can see that while D+M also specified 1.2 V/2.4 V, similar to Arcam's 1.0 V/2.0, yet the Denon X8500H's SINAD peaked at 104 dB at 1.45 V but have almost no degradation at 2 V.

So based on Arcam's specs, they have a valid argument about the test voltage of 2 V unbalance, 4 V balanced being too high for their design. However, if you don't want your power choice limited to Arcam's, for example if you want to use ATI's power amp. As ADTG mentioned, the gain of the ATI amps (the class AB ones) are typically 28 dB and you would need about 1.6 V unbalanced to drive their 200 W amps to their rated output. Or even if you prefer Arcam's power amp, you may want to some healthy headroom, say at least 2-3 dB for peaks, then I would suggest you avoid Arcam's preamps.

Now, take a look of what they said in that paper.

Below is the part that I thought was a little sad to read:

First of all, Amir used similar setup to measure several Denon, Marantz and Yamaha devices and they didn't suffer (or as much) in SINAD due to the grounding scheme.

Secondly, if Arcam knows, and obviously they do, that under some conditions there would such a ground loop that would result in higher noises, why didn't they do something to prevent it from happening? It really isn't that hard to do, there would be some cost involved, but at their price point, they should do it without any second thoughts.

Anyway, I am not going to do a point by point on their paper, suffice to say I would accept most of their explanation and believe if used carefully, the AV40 can do a good job for sure. I do wish Amir and Arcam would work out the difference, but some reason it didn't happen with Arcam's despite the fact that Amir's company is a dealer of Harman, that acquired Arcam in 2017.

For peace of mind though, even if its price is the same as the Denon, I would not pay the same for less. Less, in terms of a little bit worse in measured performance and the ability to choose from a wider range of power amps, as well as less in terms of headroom.

 

[HTNut1975]

I read that paper iirc someone linked it on ASR way back. Let's consider the following:

- The paper claimed the AV40 was rated 2 V XLR, their manual says 1 V unbalanced, 2 V balanced, so that's true.
- It also mentioned the output was designed to match their power amps, so I took downloaded the manual of their P49 power amp that is rated 200 W,, 8 Ohm, and the specs say:

I have a gazillion questions, but I don't want to waste too much of your time. It looks like Arcam's concurrently released multichannel amp (the PA720) has an input sensitivity of 800mv (and the PA240 mimics the P49 you noted). It is not clear at all to me that there is a wider range of power amps for the Denon rather than the JBL. It may be that the JBL outperforms the Denon the closer you get to its rated spec (I don't know for sure.)

I did not read the Arcam paper as saying that the balanced outs were designed for exactly 2V and nothing more--I read it as an approximation (around 2V rms). Please correct me if I am wrong, but my belief is that that means it is designed to handle (approximately) 2v continuously (I'm assuming that means without stop?). This would seem to indicate room for peaks, no? (Or, I don't fully understand the concept.) From the JBL spec sheet, it states that the "nominal" preamp is rated at 1V RMS/2V RMS with a max of 5V RMS/10V RMS. The JBL doesn't clip until a pretty high voltage, but it may begin to reduce in SINAD when you approach twice its intended nominal 2v rms, right?

You mentioned that the Denon is rated for 1.2v, but its peak performance was at 1.45v and it had little degradation up to 2v. I don't know how the Arcam/JBL would measure with unbalanced outs. I can assume the performance would be identical, but I don't know (I asked Amir to measure that, but he didn't--it would've been interesting because wouldn't the unbalanced out be grounded to the chassis?).

2v is approximately 68 percent of the Denon's rated 1.2. Suppose we had measured the JBL at 68 percent more than its rated output. What would that be? 3.36 volts? Wouldn't that put the JBL around the Denon's SINAD? But if we approached JBL's rated spec, wouldn't the SINAD go up even more?

 

[PENG]

It is not clear at all to me that there is a wider range of power amps for the Denon rather than the JBL. It may be that the JBL outperforms the Denon the closer you get to its rated spec (I don't know for sure.)

You are not alone, but I don't think Amir said that at all so where did you get that from? Amir did say "..While you do lose performance above 3.4 volts, it is not too bad up to some 8 volts which should let you drive very low gain amplifiers."

He also said something similar about Denon, "..Per requests, I turned up the volume so that we could go beyond 4 volts to see the response there for external amplifiers that are much less sensitive (green). "

Note: that the green curves shows 4.4 volts @ 92 dB SINAD for the Denon vs the JBL's 8.045 volts @ 91.747 dB SINAD, and remember, 4.4 volts unbalanced would be like 8.8 volts balanced, for many power amps that accept both.

I did not read the Arcam paper as saying that the balanced outs were designed for exactly 2V and nothing more--I read it as an approximation (around 2V rms).

If they said about 2 V that's great, sorry I misread then.... You can see that in the manual it does says 2 V for balanced, and I read the manual first so I guess it was my expectation bias.

Please correct me if I am wrong, but my belief is that that means it is designed to handle (approximately) 2v continuously (I'm assuming that means without stop?). This would seem to indicate room for peaks, no? (Or, I don't fully understand the concept.) From the JBL spec sheet, it states that the "nominal" preamp is rated at 1V RMS/2V RMS with a max of 5V RMS/10V RMS. The JBL doesn't clip until a pretty high voltage, but it may begin to reduce in SINAD when you approach twice its intended nominal 2v rms, right?

I thought I read that somewhere before, but for some reason I couldn't find it from the manual. The issue then is, if the output is actually 1 V/2 V "rated" but max 5 V/ 10 v "max", then it isn't different than that of Denon's, in fact a little better because Denon's "max" would have been about 4.4 to 4.5 V on the same basis. Yet the Denon managed 92 dB at 4.4 V as noted above earlier. So either way, you'll be the judge.

You mentioned that the Denon is rated for 1.2v, but its peak performance was at 1.45v and it had little degradation up to 2v. I don't know how the Arcam/JBL would measure with unbalanced outs. I can assume the performance would be identical, but I don't know (I asked Amir to measure that, but he didn't--it would've been interesting because wouldn't the unbalanced out be grounded to the chassis?).

What I mentioned was exactly what was shown in Amir's graphs. I don't know if the Arcam would do better with unbalanced either, my educated guess is that it would be about the same, say within 2 to 3 dB if different but I am guessing.

2v is approximately 68 percent of the Denon's rated 1.2. Suppose we had measured the JBL at 68 percent more than its rated output. What would that be? 3.36 volts? Wouldn't that put the JBL around the Denon's SINAD? But if we approached JBL's rated spec, wouldn't the SINAD go up even more?

You can just look at the graphs:
JBL SDP-55
AVR-X6700H

JBL: .........................................................at 3.4 V balanced, SINAD is 95.57 dB
Denon AVR-X6700H: ..............................at 2.0 V, unbalanced, SINAD is 100.5 dB (just eyeballing)

I used the graph for the X6700H because he plotted it for up to effectively 4.5 V, @ about 80 dB SINAD. He only plotted the AVR-X8500H for up to 2 V.

Now, my turn to ask you a question, why are you shifting between the JBL and the Arcam? Are we sure the two are exactly the same, just wearing different badges? I think they are but just want to be sure.

 

[PENG]

I just remember something, @RichB would tell you more about the importance of the first watt performance, that would mean for preamps, we may need to pay attention to the performance, such as SINAD at below 0.1 volts.

From the two graphs, you can see that at about 0.5 volt, the Denon AVR-X6700H has better than 95 dB SINAD vs the JBL's approx. 83 dB. That's a whopping 12 dB difference !! The same performance gap seems to sustain more or less as the output approaches 0 volt.

 

[HTNut1975]

@PENG I am not sure whether the JBL and Arcam is identical (probably not, but not dramatically different). I know they have different DAC’s. I made reference to the Arcam paper in part because most of the architecture seem to be the same between the two.

I asked about the voltage difference in comparing the Denon at 68 percent higher than its rated spec because from the Arcam paper, the AV40 was measured at 113 SINAD at around 2V. Now, what I don’t know is how much does the -1 dBFS makes (see their discussion on pp. 2 and 3). Maybe this is a combination of the voltage plus noise floor/ground loop explanation that brings about that measurement.

 

[HTNut1975]

From the two graphs, you can see that at about 0.5 volt, the Denon AVR-X6700H has better than 95 dB SINAD vs the JBL's approx. 83 dB. That's a whopping 12 dB difference !! The same performance gap seems to sustain more or less as the output approaches 0 volt.

Would the higher noise floor be an explanation for this? There’s about a 15 to 16 dB difference from Amir’s test to Arcam’s.

 

[PENG]

I noticed that Arcam did not mention the difference in voltage between RCA vs XLR.

Are they saying that RCA and XLR have the same voltage in the Arcam?

Maybe @gene can elaborate as well since Gene talked about the 2V vs 4V in the Yamaha CX-A5200.

Maybe this preamp voltage varies depending on whether the unit has FULLY Balanced XLR vs Unbalanced XLR?



Another thing I've noticed is that some amps have higher Gain for the XLR than for the RCA. For example, the Parasound A52+ UNBALANCED amp manual says the Volume for the XLR Input is 6dB HIGHER than the RCA Inputs.



So the Parasound XLR is 6dB Louder than RCA, but the ATI RCA is 6dB Louder than XLR!

I don't know what's going on here. It it so strange that just about everything you said in your post#78 was correct but in this post you seem to be saying something very different.

As you pointed out, Gene did talk about the 2 V vs 4 V, that is 2 V for unbalanced and 4 V for balanced, period!! It has nothing to do with fully balanced or balanced. The Arcam AV40 or the JBL SDP-55 are not fully balanced, and their specs also stated 1 V RCA/unbalanced, 2 V XLR/balanced. Always a 1:2 relationship.

Most XLR's are Unbalanced. So perhaps only Truly Balanced XLR's have DOUBLE the Voltage as RCA and Unbalanced XLR's have the SAME voltage as the RCA?

No! All XLR are used for balanced, unless/except if the XLRs are derived from those RCA to XLR converters/connectors, then it won't be balanced for the obvious reason. I supposed you meant to say most balanced amps are not fully balanced from end to end, that is, from the first input stage to the final output stage. That is most likely true, but the output voltage ratio of 1:2, RCA/unbalanced to XLR/balanced still applies whether the preamp is fully balanced or not. You don't expect the CX-A5000 series to be end to end fully balanced right? Yet as you know they XLR output rated voltage is still 2X that of the RCA output voltage.

However, on my FULLY BALANCED ATI amps (AT2005, AT3005), the RCA Input is actually LOUDER in volume than the XLR Input! The RCA has a Gain of 34dB and the XLR has a Gain of 28dB, also a Difference of 6dB, but the OPPOSITE of Parasound!

I think we have had this conversation before, this is very confusing because in the new ATI power amps manuals they no longer talk about the different gains for RCA and XLR, like they did in the manuals of the older AT2000 and AT3000 2 to 7 channel amps such as yours. Both can't be right (though anything is possible) so my guess is, there may something wrong with the newer manuals or there may be a new feature in their newer amps that automatically half the XLR input voltage while keeping the gain the same. I suggest you ask ATI for clarification on this important spec as it is very misleading. This is the case for some Outlaw amps too, may be the Monolith amps as well as all they say in the specs is, input sensitivity 1.6 V, without differentiating it for RCA/unbalanced or XLR/balanced.

The fact is, typically XLR balanced output of preamps will output 2X the voltage of RCA unbalance output so on the power amp side, they lower the gain by 6 dB for XLR input to offset the higher input voltage. This is so you can use either input, and they will be equally "loud".

What you described with you AT2005/3005 amp is exactly the same with the Parasound amp, not opposite. Except some Parasound, such as my Halo A21, has a toggle switch that selects input balanced or unbalanced. My Bryston 4B SST also has such a selector switch that changes the gain. So with the Bryston, it is possible that I can use balanced input but leave the selector switch for the input unbalanced position and it would then obviously be "louder" because it gets 2X the input voltage of the RCA/unbalanced. Conversely, if I use RCA unbalanced inputs but leave the selector in the input balanced position, then it will sound "quieter".

So it looks like your ATI amps do behave the same as typical amps with balanced inputs such as Marantz, Yamaha, Bryston, Parasound, and many more if not all. The ones in questions are the ATI amps made in recent years, probably just because they had some mistakes in the manuals, or they actually put in a circuitry to internally attenuate the XLR/balanced input voltage by half. I am not aware of any other power amps that have such feature. Again, we don't know, not without ATI confirming this one way or the other.

 

[PENG]

@PENG I am not sure whether the JBL and Arcam is identical (probably not, but not dramatically different). I know they have different DAC’s. I made reference to the Arcam paper in part because most of the architecture seem to be the same between the two.

I asked about the voltage difference in comparing the Denon at 68 percent higher than its rated spec because from the Arcam paper, the AV40 was measured at 113 SINAD at around 2V. Now, what I don’t know is how much does the -1 dBFS makes (see their discussion on pp. 2 and 3). Maybe this is a combination of the voltage plus noise floor/ground loop explanation that brings about that measurement.

I really don't want to read that paper again, but I did a text search just to make sure I didn't misread something else again. And I could not find any 113 dB SINAD at around 2 V. May be I still missed something??

All I could find for 2 V was 0.002% for the R channel, and that would be about -94 dB THD+N, or 94 dB SINAD. They got the higher number because of the way they hooked things up there was no ground loop related noise.

113 dB SINAD would put them way over the top on ASR's ranking chart assuming the way they measure truly reflect an apple to apple comparison, are you sure you read it right?

I just did another quick search for THD and found that they had 0.00099%, that's about 100 dB, at 1.92 V but that's XLR/balanced, so it needs to be compared with the Denon's SINAD at 0.96 V RCA/unbalanced.

Guys, you just have to remember, for apple to apple comparison, you have to apply the 1:2 voltage ratio for RCA/XLR. Regardless, that's 100 dB, not 113 dB so I still don't know where you read about the 113 dB. May be I missed something again, I did once, so it is possible..

 

[AcuDefTechGuy]

my Halo A21, has a toggle switch that selects input balanced or unbalanced. My Bryston 4B SST also has such a selector switch that changes the gain.

Actually all of my ATI amps I’ve owned also had the selector switch for “Balanced” and “Unbalanced“. I always used XLR and kept the switch to Balanced.

I'm always learning something new every day.

 

[HTNut1975]

@PENG , the 1.92V is the only measurement that is within the stated Arcam spec, which was what I was referencing when I said, "the AV40 was measured at 113 SINAD at around 2V." It is totally understandable why it wouldn't show up in a search because it isn't a part of the text! It is a part of the first measurement image. You can see the measurement, below:

This can be found on page 3.

And I understand what you mean with the 1:2 ratio (with respect to balanced and unbalanced connection)--I believe we were only discussing whether the Arcam was an odd duck. I say that because if their spec is that 2V RMS for XLR rather than 4V, then that might lend some evidence to the hypothesis (that it is unorthodox). But you... You actually go and look at the spec sheet! So, we have confirmation (thanks to you) that the balanced spec "nominal RMS" power for balanced out is 2V.

With respect to comparing it to the Denon's .96V, that would be fine (and it would also be within Denon's spec).

 

[HTNut1975]

@PENG

Actually, I think I may be reading that wrong (above), but I don't know. I'm not editing the post, above, so you can at least see where I got the number. I probably should find a lot of "how to read measurements 101" material!

 

[AcuDefTechGuy]

All XLR are used for balanced...I supposed you meant to say most balanced amps are not fully balanced from end to end, that is, from the first input stage to the final output stage...You don't expect the CX-A5000 series to be end to end fully balanced right?

Yeah, I definitely have a few things to learn about this Balanced business.

Another confusing fact: Both the Yamaha CX-A5200 Pre-pro and RX-A3080 Receiver have both Balanced INPUTS and Balanced OUTPUTS.

I guess some people might think this is "Balanced Input to Balanced Output".

But I guess the Balanced Inputs are converted to SINGLE-ENDED or Unbalanced Signals after the Input Stage and then converted back to Balanced at the Output Stage? That's why it's not FULLY Balanced all the way from Input to Output.

Either way, the RX-A3080 might be one of the first AVRs to have both Balanced Inputs (Stereo) and Balanced Outputs (Front L/R). Again, some people might confuse this with "Fully Balanced from Input to Output".

 

[Gmoney]

@PENG

Actually, I think I may be reading that wrong (above), but I don't know. I'm not editing the post, above, so you can at least see where I got the number. I probably should find a lot of "how to read measurements 101" material!

lol... Remember "Slew" rate is very important. Low Negative "feedback" isn't Check out Bruno P's Article on "Feedback" as for "Dampening factor" only one "Meatball" I know of on AH says it's not talked about on AH.

 

[HTNut1975]

lol... Remember "Slew" rate is very important. Low Negative "feedback" isn't Check out Bruno P's Article on "Feedback" as for "Dampening factor" only one "Meatball" I know of on AH says it's not talked about on AH.

lol. Ok, I’m going to try and be as transparent as I can. Here’s how I read part of your post:

Remember "htuzr" rate is very important. Kpt jrnusgre "feedback" isn't Check out Bruno P's Article on "Feedback" as for "Sjgkdggjg hrggjs" [I know him! I’ve listened to him and get the general idea that he is one of the pioneer’s in current amp tech! I just bought a Purifi multichannel... but not because I understand the engineering or theory behind it.]. I left “feedback” unencrypted because I think I know at least an instance of what feedback can be—when a live mic makes a feedback tone or something of the like?

 

[PENG]

Actually all of my ATI amps I’ve owned also had the selector switch for “Balanced” and “Unbalanced“. I always used XLR and kept the switch to Balanced.

I'm always learning something new every day.

Below are the source of confusion, please just focus on the "Gain" spec, and you can see the inconsistencies in the 3 specifications. If you look at your AT3005's manual, turn to the spec page, you will have the 4th version.

Common ATI, as a reputable leading power amplifier manufacturer, pleas get you act together and make your specs clear!! So please email them and let us know what they have to say. Thank you in advance.

http://www.ati-amp.com/manuals/ATIBrochure.pdf

https://www.ati-amp.com/manuals/ATIpowerampspecs.pdf

http://www.ati-amp.com/manuals/at4000manual.pdf

 

[PENG]

@PENG

Actually, I think I may be reading that wrong (above), but I don't know. I'm not editing the post, above, so you can at least see where I got the number. I probably should find a lot of "how to read measurements 101" material!

Oh, yes, I can see how you read it wrong now. It is indeed wrong, but you clearly know now. Thank you for clarifying it. Any more questions, please feel free, you probably know by now if I don't know or unsure about the answer, I will just say so.. I am just an engineer who happens to know quite a bit of math applicable to EE theories, but I am not an hifi audio amplifier designer. I mainly specialized and experienced in power, control and automation. Audio electronics, speakers etc., are just my hobbies.