AVR as pre/pro vs pre/pro, XLR vs single ended, and compatibility with high current amplifier(s)

[HSWJR]

Scooped up a Denon AVR-X3600H for $999 for my HT setup after reading in-depth reviews, watching Gene on You Tube, etc. and was convinced that it suited my application well... until I re-visited my intended use a little more thoroughly. The available literature shows my intended Front L-R-C amp wanting high voltage to feed them (4V; they are Krell amps, specifically, the KAV-250a/3, which is "Class A/B" per Krell, plenty of power, demands voltage, and they also exhibit a +6B more gain when using XLR as opposed to single ended (RCA) connections. The Amp will only be 6 feet from Pre-pro or AVR, so the normal reason of cable length is not a factor, but the 6 db probably will be, albeit not as much as the voltage needs. The Owners Manual of the Krell Amplifier states: "Krell recommends using balanced interconnect cables. Balanced interconnect cables not only can minimize sonic loss but are also immune to induced noise, especially with installations using long cables. Balanced connections have 6 dB more gain than single ended connections. When level matching is critical, keep this gain value in mind." Neither the 3600 nor the 3700 have balanced outputs, so even though they (amazingly) spec better than the Marantz 7705 when you use them as a pre-pro (the 3600 by re-assigning the amps, the 3700 if you "shut the amps out" of the equation), because the Krell wants tons of juice and XLRs, I am thinking that I may need to reconsider the 7705 in spite of the better specs of either of the Denon AVRs. Being that the 3600 is unopened and I am within the return window for another week, I was going to substitute the 3700 for the 3600 as the 3700 had a better "shut off" for the internal amplifiers making it more akin to a true "pre-amp/processor" (if what I read was correct, and since I do not intend to use any of the internal amps for any reason whatsoever, the 3700 looked like a better fit. Again, not my situation due to the powers demand/gain required by the Krell amps... so I think I'd be better of with the Marantz 7705... or am I wrong?

 

[warnerwh]

According to the specs for your amp in the manual: https://www.manualslib.com/manual/90319/Krell-Industries-Three-Channel-Power-Amplifier-Kav-250a-3.html?page=34#manual the input sensitivity is 2.15 volts with 26.4 db of gain. I assume these specs are for a single ended (rca) connection. You'll be fine with the 3700 using the rca connections if you use preamp mode.

 

[HSWJR]

Nice! Nothing like saving $800 over the AV7705. I assume that is what you would choose? The 3600 spec'd better than the 7705, so I assume the 3700 will be the same, or dang close. I don't want buyer's remorse, and really $800 is not a big deal to me if there is anything to be gained. If not, then great. I was a bit concerned with using two big 5 channel Marantz amps (the MM7055's, I will use two), plus the KAV (250w x3) , plus an SACD, plus the Panasonic DP-UB9000P-K, and maybe even a turntable and turntable pre, plus some subs... it all adds up to a huge potential for noise (lol- the bad kind) and I assume the XLRs of the 7705 would help with that... but if there is no real possibility of there being any difference between the two insofar as induced noise goes, the the 3700 gets it, right? Any thoughts on that?

 

[warnerwh]

You can read a good and thorough review of the 3700 here: https://www.audiosciencereview.com/forum/index.php?threads/denon-avr-x3700h-avr-review.15031/page-34#post-640036

 

[HSWJR]

Thanks for the advice, especially letting me know that the Denon (either of them) will drive the KAV channels to their full potential. 26.4db gain is plenty I suppose, although I wish I could predict whether I will be dealing with unwanted noise with all these components, because if so I will kick myself for being penny-wise and ignoring the Krell playbook regarding XLRs having less noise not to mention +6db gain. Seems like the 3700 has better and more advanced processing and better specs than the 7705 (newer chips/features), and of course $1200 is better than $1800. I hope someone who has a comparable setup (high power XLR capable amps plus a budget friendly pre/pro or AVR) chimes in, or maybe someone with hands-on experience with the 7705 and either the 3700 or 3600 running as a pre/pro only... if not, those be the breaks as it were. Thanks again for the insight. At least that question (gain) is out of the way. Marantz may not survive with the competition Denon is bringing. I don't know how or if the parent corp (SU) keeps things amicable amongst the children... maybe healthy competition keeps them all from getting complacent.

 

[lovinthehd]

The advantage of a balanced connection in terms of noise rejection is just in terms of rejection of noise incurred for that particular connection, it's not a sponge to clear up other issues. With the sensitivity level of the Krell you may come up a bit short of full power without clipping using the Denon, but I wouldn't particularly worry about it in terms of lost wattage output (maybe @PENG will be kind enough to offer his opinion and calculation skills).

 

[HSWJR]

Very cool. If he does, great. Jedi, sure you don't sell Denons? lol JUST KIDDING. The help I got here has been AMAZING and much appreciated. EIther will liekly be awesome (especially considering the one I am using now is a 20 year old Krell HTS which was awesome back then but cumbersome and not really adequate in any way other than sound quality since about 2005 or so. I might be able to get $150 for it if I am lucky lol).

 

[lovinthehd]

Very cool. If he does, great. Jedi, sure you don't sell Denons? lol JUST KIDDING. The help I got here has been AMAZING and much appreciated. EIther will liekly be awesome (especially considering the one I am using now is a 20 year old Krell HTS which was awesome back then but cumbersome and not really adequate in any way other than sound quality since about 2005 or so. I might be able to get $150 for it if I am lucky lol).

I use a couple and find them a good value....but you already bought it I thought? May as well give it a shot in any case if you did. Good luck!

 

[HSWJR]

3600 is unopened and headed back... for replacement with 3700 or Marantz 7705 is my guess. I guess I will have time to decide as I need to finish the barn door project to keep the 4 legged demons out of my AV room lol. The Krell HTS is going one way or another.

 

[PENG]

Thanks for the advice, especially letting me know that the Denon (either of them) will drive the KAV channels to their full potential. 26.4db gain is plenty I suppose, although I wish I could predict whether I will be dealing with unwanted noise with all these components, because if so I will kick myself for being penny-wise and ignoring the Krell playbook regarding XLRs having less noise not to mention +6db gain. Seems like the 3700 has better and more advanced processing and better specs than the 7705 (newer chips/features), and of course $1200 is better than $1800. I hope someone who has a comparable setup (high power XLR capable amps plus a budget friendly pre/pro or AVR) chimes in, or maybe someone with hands-on experience with the 7705 and either the 3700 or 3600 running as a pre/pro only... if not, those be the breaks as it were. Thanks again for the insight. At least that question (gain) is out of the way. Marantz may not survive with the competition Denon is bringing. I don't know how or if the parent corp (SU) keeps things amicable amongst the children... maybe healthy competition keeps them all from getting complacent.

The 3700 has more processing features but the chip set that affects sound quality related specs without DSP has not changed, same as the 3600 and the 7705, 8805.

Per HD, I just did some calculations for you:

- At 2 V pre out, the Krell amp would be driven to output 218.3 W, or 436.6 W into 4 Ohms.
- At that level, the 3600's center channel measured 74.548 dB SINAD, 100.352 dB for the left channel.
- The 7705 measured 74.55 dB at 3.955 V (XLR), that would be 1.9775 V (RCA).
- The Krell 250a/3's output voltage is 49 Vrms.
- To drive the Krell to its theoretical maximum output (49 V, 300 W into 8 Ohm), the 3600 needs to output 2.34 Vrms.
- At 2.34 Vrms pre out level, the X3600H was not measured, but based the shape of the curve, it would be reasonable to assume about 72 dB SINAD, or 0.025% THD+N

So you can see that even if you drive the Krell to its maximum output (that's 300 W into 8 Ohm or 600 W into 4 Ohm, the 3600 will still not be the weak link, and the Krell would be clipping like crazy at that point already, with THD+N > 1% for sure.

The AVR-X3600H measured better than AV7705 in just about (AV7705 did 1 dB better in linearity) every single test done on the ASR bench. It does not mean you can hear a difference between the two, but I see no audio advantage buying the outgoing AV7705 especially if you have use for the power amps in the AVR-X3600H.

I also consider $800 not a big deal if buyer's remorse is a concern. If it is my money, I would wait for the AV7707 (I would skip the 7706) and see if by then Marantz would let the SR8015's better HDAMs trickle down to the lower models. As it is now, it would appear the 8015 is the only one that measured as good as the Denon AVRs, likely because of the HDAM (Marantz silly game in my opinion, the best upgrade would be to cancel them) upgrade.

 

[HSWJR]

If I did wait for the 7707, do you think we are talking about 6 months or maybe more? To mix it up a bit, last night my weary head got to thinking that I'd be better off just pulling the Krell KRC-3 (a 2 ch pre-amp) out and using the pre/pro instead, meaning the Krell FPB-200 Amp I was going to leave as dedicated 2 channel via the KRC would be re-purposed back into the HT system (driving Dunlavy SC-IVs... have I revealed my age better than any picture of gray hair might lol?) , and given that beast may need more juice from the pre, wouldn't that mitigate in favor of waiting for the 7707 even more (XLR outputs to the FPB = 6 db more gain?), or should that monster amp go back to a cage somewhere along with the oak twin towers? A lot to unpack, and no rush either. I can see myself just getting the 3700 as a place setter if the 7706 is a downgrade for me, and waiting for the 7707 if it will be 6 months or more. I was just curious how the increased demand of the FPB might change things up in the 7706 vs 3700 vs wait for 7707 conversation. If I am getting greedy with your time, tell me to go figure it out and I will laugh and thank you anyway for your measurements. So glad I found this forum.

 

[PENG]

If I did wait for the 7707, do you think we are talking about 6 months or maybe more? To mix it up a bit, last night my weary head got to thinking that I'd be better off just pulling the Krell KRC-3 (a 2 ch pre-amp) out and using the pre/pro instead, meaning the Krell FPB-200 Amp I was going to leave as dedicated 2 channel via the KRC would be re-purposed back into the HT system (driving Dunlavy SC-IVs... have I revealed my age better than any picture of gray hair might lol?) , and given that beast may need more juice from the pre, wouldn't that mitigate in favor of waiting for the 7707 even more (XLR outputs to the FPB = 6 db more gain?), or should that monster amp go back to a cage somewhere along with the oak twin towers? A lot to unpack, and no rush either. I can see myself just getting the 3700 as a place setter if the 7706 is a downgrade for me, and waiting for the 7707 if it will be 6 months or more. I was just curious how the increased demand of the FPB might change things up in the 7706 vs 3700 vs wait for 7707 conversation. If I am getting greedy with your time, tell me to go figure it out and I will laugh and thank you anyway for your measurements. So glad I found this forum.

I believe Krell amps were designed for audiophiles who likely believe in audio myths (to some extent) including the one that says higher distortions is worth it for the sake of less negative feedback being used. To me, it doesn't matter how much an amp weight, class (A, A/AB, AB), lower -ve feedback etc., it can't beat an amp that has much lower distortions and noise, all else being equal, but that's just me.

On the objective side, my calculations show even 2.5 V will push any of your Krell amps to their output limit so I am not sure why you want the 2X voltage the 7705's XLR offer. Its not even a headroom issue!!

So in my opinion, it is better to get the 3700 or even the 3600 to conserve cash, and then if the 7707 in fact measures as good or better than the Denons then pounce on it. On money no object issue, then all bets are off, but then you may as go for AVPs instead of AVRs and pseudo AVPs such as the Marantz 770X or even 880X.

If you still want XLR regardless, you may want to consider going with the 7706, or the Yamaha CX-A5200 at year end when their prices may drop significantly. It is true that the difference in SINAD between the Marantz and Denon seems huge, but a) most of the time the pre out output voltage would be below 1V, so for real world use, the difference would become much less, b) at near rated output of your Krell amps, the 7705's (likely the 7706 too) SINAD will be much higher, but as shown in my calculations, the distortions will still be much lower than that of the Krell power amps (based on their published specs), so I don't expect audible effects either. In fact, even if you have a perfectly transparent power amp, I highly doubt you can hear the difference between 70 dB SINAD and 95 dB SINAD, >90% of the time.

Just a cautionary note on XLR vs RCA in terms of pre amp output and power amp gain:

For some power amps, such as Marantz, Bryston, Anthem's and many more, if you use XLR input, the gain will be 6 dB lower, to maintain practically the same overall gain when paired with a preamp that has its XLR output 2X that of the RCA output. Krell's power amps, at least the models you have, do have the same gain XLR or not.

 

[PENG]

One thing to keep in mind, to match the major feature set (XLR inputs) of the AV7706, you should consider the AVR-X4700H, not the X3700H unless things like front hdmi port, Auro3D, larger display etc., are of no use to you.

 

[HSWJR]

"I believe Krell amps were designed for audiophiles who likely believe in audio myths (to some extent) including the one that says higher distortions is worth it for the sake of less negative feedback being used. To me, it doesn't matter how much an amp weight, class (A, A/AB, AB), lower -ve feedback etc., it can't beat an amp that has much lower distortions and noise..."

Amen brother. Had those things since the 1990's and while an improvement over Onkyo and NAD etc they are not a good value, nor were they then, for someone seeking musicality. I will say though, that the upper end Krells really shone at huge amounts of power like the FPB-600 could make, when paired with great speakers like the old Genesis Vs, they were in another league. My mistake was thinking the FPB-200s etc would be close. They aren't. I looked up the FPB-200 and discovered that it needs a little less signal strength (in voltage) from the preamp than the KAV-250a/3 which really surprised me. closer to 2v than the KAV surprisingly. It seems like I could move both the Krells out of the system and go with the two 7055s and a bridged 2 channel for teh center like a Proteon AA1150 I have somewhere... would you do that? My speakers are Dunalvy Audio Labs SC IVs whihc are rated at 91 sensitivity and 5 ohms nominal, but they dip down to 3 ohms too... I guess I could run them as "small" instead of large but that seems a bit strange given their size lol.

And thanks also for the insertion of the Yamaha etc into the discussion... I was about to get the Yamaha CX-A5200 instead of the Marantz but if I recall correctly it had a bugaboo as well, and one that Yamaha was not even going to attempt to fix this generation (from reading one of Gene's pieces). I can care less about 8K or game devices, so I hope that lets me enjoy some savings by getting an older model rather than a newer model of whichever I eventually go with- hence my interest in the 7705. Now I am not even considering the 7705, but if it were between the 7706 and the Yamaha 5200, which would you go with? I was almost sold on the 5200 as I have an 11 channel set-up. Also, when you said "you may as go for AVPs instead", which ones sub$3K have caught your eye lately? It would be really easy to justify the Yamaha if you think it beats the 7706, or perhaps an AVP as you mentioned. I like my SACDs and 2.1 channel listening, but it may just be that I have been running a fools errand with the Krells (I suspected as much when I went to hear a friend of mine's M. Levinson setup with Revel Ultima Gems but that rig made mine look affordable lol- and those were 1999 dollars), so I am getting a little excited about improving the fidelity of my "audio mediation sessions."

 

[PENG]

My mistake was thinking the FPB-200s etc would be close. They aren't. I looked up the FPB-200 and discovered that it needs a little less signal strength (in voltage) from the preamp than the KAV-250a/3 which really surprised me. closer to 2v than the KAV surprisingly.

You weren't wrong about them being close, in fact they have exactly the same gain, 26.4 dB. The KAV needs a little less input voltage only because it is rated only 200 W, 8 Ohm, vs the FPB-200's 250 W into 8 Ohm. With 1.92 V from the preamp, either amp will output about 200 W into 8 Ohm.

It seems like I could move both the Krells out of the system and go with the two 7055s and a bridged 2 channel for teh center like a Proteon AA1150 I have somewhere... would you do that? My speakers are Dunalvy Audio Labs SC IVs whihc are rated at 91 sensitivity and 5 ohms nominal, but they dip down to 3 ohms too... I guess I could run them as "small" instead of large but that seems a bit strange given their size lol.

Bridging a good power amp rated for 4 Ohm is okay for 8 ohm nominal speakers. If you do that with the Marantz MM7055 (assuming that's what you referred to), you risk damaging it and void the warranty.

And thanks also for the insertion of the Yamaha etc into the discussion... I was about to get the Yamaha CX-A5200 instead of the Marantz but if I recall correctly it had a bugaboo as well, and one that Yamaha was not even going to attempt to fix this generation (from reading one of Gene's pieces).

You are right, if you use XLR, you will get higher distortions though as Gene mentioned, the level would still be below the threshold of audibility, probably about the same as the AV7705 if I remember right. The CX-A5100 did not have that issue, but I doubt you can find one.

I can care less about 8K or game devices, so I hope that lets me enjoy some savings by getting an older model rather than a newer model of whichever I eventually go with- hence my interest in the 7705. Now I am not even considering the 7705, but if it were between the 7706 and the Yamaha 5200, which would you go with?

If I am in the situation you are in, and cannot wait, then I would just get the X3600H or X4500H and keep the savings in the bank while waiting things to shake out.

I was almost sold on the 5200 as I have an 11 channel set-up. Also, when you said "you may as go for AVPs instead", which ones sub$3K have caught your eye lately?

None at the moment, unfortunately. In fact, even for 6 K, I can't think of any. At the price point of $5 to 7K there are a couple that comes with Dirac Live but I am confident in their reliability and may not be bug free yet at the moment. Even if those are not concerns, I would only consider them if I were much richer. I think I am going to stay with my cheap X4400H (replaced my AV8801) for a couple more years. By the way, today I spent some time listening to my HD tracks using the AV8801, and no matter how hard to try, I just don't think it sound any better/different than the X4400H (used as prepro).

[/QUOTE] It would be really easy to justify the Yamaha if you think it beats the 7706, or perhaps an AVP as you mentioned. I like my SACDs and 2.1 channel listening, but it may just be that I have been running a fools errand with the Krells (I suspected as much when I went to hear a friend of mine's M. Levinson setup with Revel Ultima Gems but that rig made mine look affordable lol- and those were 1999 dollars), so I am getting a little excited about improving the fidelity of my "audio mediation sessions."
[/QUOTE]

Going by the measurements the CX-A5100 should beat the 7705 (and the 06 assuming the audio performance would be the same). The CX-A5200 too, if you use RCAs.

 

[PENG]

I forgot to mention that the SC IVs really have good sensitivity so they are not really hard to drive. Impedance is low, but phase angles vs frequency looks very good. So pre out voltage is not as much an issue at all, because for those speakers, it is the power amp's current capability that is more important. Your Krell amps are excellent match for them in that sense. I would consider those truly high current amps.

 

[HSWJR]

I found a Yamaha CX-A5100 11.2-CH MusicCast Preamplifier for $2,299.00... ready to pull the trigger and call it good... as opposed to denon avr-x3700h? pretty sure peng's supply of patience has been taxed to its limit lol... Peng? Anyone?

 

[AcuDefTechGuy]

I vote for the CX-A5200 or CX-A5100.

 

[HSWJR]

CX-A5200 was the one with a strange issue that was not going to be addressed, right? Meaning the single ended performed better than the XLR in the L and/or R front (main) channels, right? The A5100 on the other hand did not exhibit that peculiarity if memory serves, or did I get them mixed up? I think it was something Gene encountered some time back (in the last year or two I think).

 

[MrBoat]

You weren't wrong about them being close, in fact they have exactly the same gain, 26.4 dB. The KAV needs a little less input voltage only because it is rated only 200 W, 8 Ohm, vs the FPB-200's 250 W into 8 Ohm. With 1.92 V from the preamp, either amp will output about 200 W into 8 Ohm.



Bridging a good power amp rated for 4 Ohm is okay for 8 ohm nominal speakers. If you do that with the Marantz MM7055 (assuming that's what you referred to), you risk damaging it and void the warranty.



You are right, if you use XLR, you will get higher distortions though as Gene mentioned, the level would still be below the threshold of audibility, probably about the same as the AV7705 if I remember right. The CX-A5100 did not have that issue, but I doubt you can find one.



If I am in the situation you are in, and cannot wait, then I would just get the X3600H or X4500H and keep the savings in the bank while waiting things to shake out.



None at the moment, unfortunately. In fact, even for 6 K, I can't think of any. At the price point of $5 to 7K there are a couple that comes with Dirac Live but I am confident in their reliability and may not be bug free yet at the moment. Even if those are not concerns, I would only consider them if I were much richer. I think I am going to stay with my cheap X4400H (replaced my AV8801) for a couple more years. By the way, today I spent some time listening to my HD tracks using the AV8801, and no matter how hard to try, I just don't think it sound any better/different than the X4400H (used as prepro).

It would be really easy to justify the Yamaha if you think it beats the 7706, or perhaps an AVP as you mentioned. I like my SACDs and 2.1 channel listening, but it may just be that I have been running a fools errand with the Krells (I suspected as much when I went to hear a friend of mine's M. Levinson setup with Revel Ultima Gems but that rig made mine look affordable lol- and those were 1999 dollars), so I am getting a little excited about improving the fidelity of my "audio mediation sessions."


Going by the measurements the CX-A5100 should beat the 7705 (and the 06 assuming the audio performance would be the same). The CX-A5200 too, if you use RCAs.

I had to add a like just for the thought and information in that post, not to mention the others. I sure hope you get paid for knowing all that about current AV products, and if not, you sure ought to be.