Marantz SR7002

[KEW]

In the case of the Marantz, unless it has a severe limitation in its output devices the results should be electically near the same, and acoustically indistinguishable.

So if I follow correctly, even though Marantz advertises their receiver as having a discrete channel amp, the channels are not very discrete (since all channels draw their current from two shared capacitors and a single transformer)?

 

[Seth=L]

So if I follow correctly, even though Marantz advertises their receiver as having a discrete channel amp, the channels are not very discrete (since all channels draw their current from two shared capacitors and a single transformer)?

It has discrete output devices as apposed to integrated output devices commonly found on lower quality/cost components. Most power amplifiers are not entirely discrete either. The output channels are discrete, but they design is not modular with monoraul power supplies for each channel. Such a design in a receiver would have inherent problems with sustaining any substantial level of output.

 

[swspiers]

It has discrete output devices as apposed to integrated output devices commonly found on lower quality/cost components. Most power amplifiers are not entirely discrete either. The output channels are discrete, but they design is not modular with monoraul power supplies for each channel. Such a design in a receiver would have inherent problems with sustaining any substantial level of output.

It might not sustain ouptut, but it would be one heck of a toaster oven...

In all seriousness, I doubt I would every look for modular amps in an AVR. A Theta Dreadnaught ( my fantasy amp- just because) is something I would look for with modular design.

then again, why stop there? Parasound JC1 monoblocks all around

 

[lietuvis91]

I thought that bi-amping and bi-wiring were interchangeanle terms?!

What i am doing, is using the front channels and some multi-speaker channels to feed my 2 speakers. I hooked it up according to the manual, and fliped some switch on the back of the receiver to enable this function. The manual calls it bi-amping and says it feeds the highs and lows through separate channels.

I did a back to back comparison between bi-amped and not, and can definitely notice a difference in the clearity and quality of the highs and the lows. Bi amping just "woke" these speakers up. Also, i can clearly tell the receiver is running a good bit hotter when setup this way, so if nothing else, this seems like confitmation that it is working harder.

anyway, i'm not going back to non-bi-amped mode, there's a clear difference.

 

[bandphan]

I thought that bi-amping and bi-wiring were interchangeanle terms?!

What i am doing, is using the front channels and some multi-speaker channels to feed my 2 speakers. I hooked it up according to the manual, and fliped some switch on the back of the receiver to enable this function. The manual calls it bi-amping and says it feeds the highs and lows through separate channels.

I did a back to back comparison between bi-amped and not, and can definitely notice a difference in the clearity and quality of the highs and the lows. Bi amping just "woke" these speakers up. Also, i can clearly tell the receiver is running a good bit hotter when setup this way, so if nothing else, this seems like confitmation that it is working harder.

anyway, i'm not going back to non-bi-amped mode, there's a clear difference.

FWI, You are passive biamping, which has no benefit other than additional output. The "high and low" feeds(terminals) you are talking about still go threw the same crossover as if they were hooked up with a jumper That clear difference is just perceived.

 

[lietuvis91]

what do you mean by additional output?

my polk towers have 2 separete sets of hookups for this specific purpose to separate the feed of the highs/lows. I just can't imagine why speaker manufacturers would include the bi-amp option, in conjunction with receiver manufacturers, and that there would be no benefit. Why go through the trouble just so that poelpe think they "perceive" a difference? It does not make sense... plus my ears tell me otherwise...

 

[bandphan]

what do you mean by additional output?

In theory and with two channels, you supply the speakers with additional watts. Since these watts are coming from the same power supply, how much is debatable. Very few speakers are designed with passive bi amping in mind, very, very few. Bi amping with separate amps, and an active crossover, is where the benefit comes in.

 

[bandphan]

what do you mean by additional output?

my polk towers have 2 separete sets of hookups for this specific purpose to separate the feed of the highs/lows. I just can't imagine why speaker manufacturers would include the bi-amp option, in conjunction with receiver manufacturers, and that there would be no benefit. Why go through the trouble just so that poelpe think they "perceive" a difference? It does not make sense... plus my ears tell me otherwise...

again when you dont have it bi amped you use jumpers which sends the signal thru the same passive crossover.

edit: your polks so called "specific purpose" is more marketing. Just stop and think about it for a minute, thats all. Use the search feature here to find the countless threads that this discussed (in the speaker section also)

edit 2...done correct

 

[GranteedEV]

Since these watts are coming from the same power supply, how much is debatable.

Well, Marantz receivers seem to put out ~70% of their rated 2ch output into 5ch, All Channels Driven. Maybe giving it a slight boost (to 75%) into four "channels" it's probably safe to say that we're going from the 7002's rated 125 wpc to maybe 185wpc or so... although I'm not sure how receiver bi-amping really works. In my mind at least, running the same signal through two different amp channels and then combining it at the speaker would only increase THD

What he's probably perceiving is either

a) maybe improved headroom or control for a power hungry, low imedance speaker (not likely, these things are rated at 90 dB sensitivity and 8 ohms, which should be a cinch for an SR7002 and the additional wattage should only come to play as you approach or exceed levels...)
b) a slight 1 or 2 db volume increase (maybe by passively bi-amping, the gain changes... the ONLY way to properly do an A/B comparision of two methods or pieces of equipment is to make sure the sound pressure levels are perfectly matched with a meter.)
c) his receiver (SR7002) has some built-in digital active crossover that perfectly blends the polk m70 tweeter with the mids better than the polk's internal crossover, and the m70s have a removable jumper which lets you bi-amp properly.


My money? Would be on choice B.

I just can't imagine why speaker manufacturers would include the bi-amp option, in conjunction with receiver manufacturers, and that there would be no benefit.

Were there jumpers that you removed on the polks?

Anyways, it's because there's so much snake oil out there that people don't know what to believe. Speaker and Electronics manufacturers just want to be able to advertise they too have a feature so they're not undersold. You really think that when you see 100,000 speaker hooked up by 5 feet of 4awg speaker hose, that the signal going to the speaker is going to improve? Even though the interior of the speaker probably uses an equal 5 feet of 14 awg speaker wire?

It's kinda like that. If people want to do something, manufacturers don't want complaints about how it's not an "option". Sometimes these "features" can even compromise the product... i was reading this site's review of the EMP e5ti and the first generation came with a dual binding post just like your polks... read the note:

http://www.audioholics.com/reviews/speakers/floorstanding/emp-tek-impression-e5tir/e5ti-build-quality

 

[KEW]

It might not sustain ouptut, but it would be one heck of a toaster oven...

In all seriousness, I doubt I would every look for modular amps in an AVR. A Theta Dreadnaught ( my fantasy amp- just because) is something I would look for with modular design.

then again, why stop there? Parasound JC1 monoblocks all around

I agree with you, but since Marantz claims "discrete channels", modular amps is what came to mind.
Certainly, I did not mean to imply that the Marantz is inferior to other mainstream receivers.

So, do virtually all mainstream receivers have discrete outputs? Or is Marantz really doing something a little better by having discrete outputs?

 

[KEW]

Sometimes these "features" can even compromise the product... i was reading this site's review of the EMP e5ti and the first generation came with a dual binding post just like your polks... read the note:

http://www.audioholics.com/reviews/speakers/floorstanding/emp-tek-impression-e5tir/e5ti-build-quality

Yikes! So the EMP's can get fried from "bi-amping"! What is causing this? is having two channels feeding the same speaker increasing the current?
Would this only apply to true modular amps?

 

[swspiers]

FWI, You are passive biamping, which has no benefit other than additional output. The "high and low" feeds(terminals) you are talking about still go threw the same crossover as if they were hooked up with a jumper That clear difference is just perceived.

I'm not going to claim that I fully grasp this concept as it's not a feature I look for. But from the manual:

A bi-amp connection is possible with speakers that
have two sets of inputs (for treble and bass).
This allows you to drive the treble and bass units
with separate channel amps, which enables better
sound quality. Connect the speakers as shown in the
fi gure. Set the SPEAKER C selector switch on the
rear panel to ON.
Notes:
• If incorrectly connected, a protective circuit in
the unit will trip and set the unit to standby. (The
STANDBY indicator will flash.) In such case,
recheck the connections between the speakers and
the unit.
• Turn power to the unit off before changing the
setting of the SPEAKER C selector switch.

Gawd, that is just so vague!

Anyway, my (limited) understanding is that there are two amplifiers now powering the speaker. Each set of posts 'filters' the appropriate frequency range to the corresponding driver: more power (actually, I believe it is current).

I am totally unsure how the benefit would be merely 'perceived'

For what it's worth, I'm pretty much a "straight wire with gain" guy when it comes to amplifiers. I doubt there are very many actual differences in amplifiers, assuming they are level matched and decent quality. Differences for me lie in total current output, noise, channel cross-talk, gain and type of feedback employed.

So- I'm not looking for debate. I just don't think I fully grasp how this is passive, and not truly affecting sound quality

 

[bandphan]

I'm not going to claim that I fully grasp this concept as it's not a feature I look for. But from the manual:

A bi-amp connection is possible with speakers that
have two sets of inputs (for treble and bass).
This allows you to drive the treble and bass units
with separate channel amps, which enables better
sound quality. Connect the speakers as shown in the
fi gure. Set the SPEAKER C selector switch on the
rear panel to ON.
Notes:
• If incorrectly connected, a protective circuit in
the unit will trip and set the unit to standby. (The
STANDBY indicator will flash.) In such case,
recheck the connections between the speakers and
the unit.
• Turn power to the unit off before changing the
setting of the SPEAKER C selector switch.

Gawd, that is just so vague!

Anyway, my (limited) understanding is that there are two amplifiers now powering the speaker. Each set of posts 'filters' the appropriate frequency range to the corresponding driver: more power (actually, I believe it is current).

I am totally unsure how the benefit would be merely 'perceived'

For what it's worth, I'm pretty much a "straight wire with gain" guy when it comes to amplifiers. I doubt there are very many actual differences in amplifiers, assuming they are level matched and decent quality. Differences for me lie in total current output, noise, channel cross-talk, gain and type of feedback employed.

So- I'm not looking for debate. I just don't think I fully grasp how this is passive, and not truly affecting sound quality

Just think about it, whether or not you are using separate amps in an AVR its a single power supply, so there is limitation 1. The next would be that the power divide is the same in the passive crossover, just being feed "possibly" more power(current), therefore it can not change the sound only* the output, the passive crossover can not change limitations as if the jumpers were in place and no bi amping was taking place. thats 2.
*Your point about THD is correct, that is another deterrent.

 

[GranteedEV]

Just think about it, whether or not you are using separate amps in an AVR its a single power supply, so there is limitation 1.

Well, in this case, while that's true, we are talking about a well built 7 channel receiver that's got a beefy power supply that's only trying to feed 4 channels. I think 90wpc is a safe assumption into 4 channels, which translates into ~180wpc into 2 "dual" channels or what-have-you.

Anyway, my (limited) understanding is that there are two amplifiers now powering the speaker. Each set of posts 'filters' the appropriate frequency range to the corresponding driver: more power (actually, I believe it is current).

I am totally unsure how the benefit would be merely 'perceived'

It's like this: there's

1) no active crossover splitting the signal before it arrives to the speaker IE each channel is sending a full range signal AFAIK. Even if either speaker channel is sending a certain frequency range (IE 35hz-1khz and 1khz to 20khz maybe), that's not the actual crossover. The speaker might be ideally crossed over at 3khZ with a 4th order slope - there's no way the amp would know this unless you manually separated the input signal before it ever got to the amplifier IE the real benefits of true bi-amping.

2) still a passive crossover in the speaker splitting the signal before it arrives to the drivers. The true benefit of bi-amping is that it lets you play around with crossover frequencies, slopes, etc until you find the best interaction between your drivers. Basically, if one amp channel sends a 1khz signal through a crossover that hi passes anything above 3khz to the tweeter, and low passes anything below that to the woofer, then it's going to the woofer again, which defeats the purpose of bi-amping in the first place. The only way to truly bi-amp is to take the passive crossover out of the equation entirely, which in turn would mean opening up your speaker and missing around quite a bit with the wiring AFAIK.

Considering those two things, we basically know that in order to get 90db of volume at 1 m, the polks require ~1w of power.

So in mode A, regular amplification, we send 1w of power in the signal to the speaker and it outputs 90db of SPL at 1 m.

in mode B, "passive-bi-amped", we send (.35)w @ 0.01% THD of power of high frequencies in the signal to the speaker through one amp channel, plus (.65)w @ 0.01% THD of power of low frequencies through another amp channel. Once it arrives at the speaker, the speaker VERY LIKELY really has no way of sending these separate signals to the drivers, and would just combine into 1w (although now our THD may be 0.015 or 0.02 or something because the two amps introduce different harmonic distortion), which becomes 90db of SPL out of the speaker.

So even if the latter mode is more capable of delivering power (to a max assumed output of maybe 185wpc[92.5 x 2] compared to 125wpc), at any reasonable output level, I'm just not seeing how there would be a perceivable difference of sound - unless of course, at a volume of say "-35db" Mode A is sending 1 w of power and mode B is sending 1.5 watts of total power, in which case, the percievable difference is because the two setups are not level matched.

Of course, at louder volumes that straddle its rated max specs, you could probably experience improved dynamics as a result of the extra headroom IE "more output". I don't see that as improved sound quality though, just "cleaner when louder"

 

[swspiers]

Hey Liet!

I hope you're still enjoying your new receiver!

I, for one, totally believe that your speakers sound better after bi-amping- regardless of the physics involved. I hope you don't have a sour taste after the lively debate, and information, we had a chance to glean from more educated posters.

I will qualify my belief though. I have learned over the past 2 years to take into account every variable that I'm aware of before I determine what affected what.

I can state, which is pretty much beyond (practical) dispute, that my system sounds better at this moment than I honestly thought possible. I cannot account for the difference moving from separates to the AVR. It could be as simple as the crossover @ 60 Hz. I'm pretty darn sure that Audyssey has a lot to do with it. But in the spirit of the axiom that one cannot prove a negative assertion, I can't rule out the possibility that there are magic pixies in the SR7002 that embue the exiting soundwaves with magic pixie dust either

I bought an AVR because my current system resides in a TV stand. It's a little impractical to have a near 100-pound monster amp running a modest 2-channel system. It offends my sense of 'synergy'. I never expected the quality to much, let alone exceed, what I had with the Parasound gear. It does.

In the end, the only reason I'm going to spend time trying to figure out EXACTLY what is going on is so that I can make smarter decisions in the future.

So yeah- bi-amp the heck out of those speakers, dude! Keep letting us know what you hear. Then we can all have fun figuring it out...