HTPC audio Bi-wire(amp?) or not

H

Hades16x

2[H]4U
2FA
Joined
Sep 24, 2003
Messages
3,979
So I'm rearranging my room to better my movie watching enjoyment. For Christmas I replaced my Onkyo TSXR 705, with a 707. With my new room orientation, I have the ability to expand to 7.1. Most of my movies are blu-ray disks(PS3), but for simplicity sake I've ripped them all to .mkv's for my HTPC.

Enough with the chatter, here are the choices:

A) Bi-wire my front speakers
B) Don't bi-wire and go for 7.1

Please keep in mind that I use my HTPC for music also while entertaining.
The receiver uses the Surround Back L/R(Zone2) for the bi-amp mode, so I cannot do both 7.1 and bi-amp simultaneously.

I realize I switched up bi-amp/wire throughout my question. I'm not quite sure how the Onkyo does it. It is to my knowledge the a true bi-amp is done with two separate amplifiers, but through my searches on the interwebz, the Zone 2 has a separate amplifiers, so I guess it's more similar to bi-amp rather than bi-wire.

Any input on what would be better?

BTW my front speakers are Polk Monitor 70's and my rears are Monitor 40s.

Thanks,
Michael
 
Don't biwire or biamp. Neither are very useful. The only real reason to biamp when dealing with a passive crossover is if you have smaller amps and need more power to the speakers. Biamping is only really useful with active crossovers (a crossover before the amps).
 
Cloud15x said:
So I'm rearranging my room to better my movie watching enjoyment. For Christmas I replaced my Onkyo TSXR 705, with a 707. With my new room orientation, I have the ability to expand to 7.1. Most of my movies are blu-ray disks(PS3), but for simplicity sake I've ripped them all to .mkv's for my HTPC.

Enough with the chatter, here are the choices:

A) Bi-wire my front speakers
B) Don't bi-wire and go for 7.1

Please keep in mind that I use my HTPC for music also while entertaining.
The receiver uses the Surround Back L/R(Zone2) for the bi-amp mode, so I cannot do both 7.1 and bi-amp simultaneously.

I realize I switched up bi-amp/wire throughout my question. I'm not quite sure how the Onkyo does it. It is to my knowledge the a true bi-amp is done with two separate amplifiers, but through my searches on the interwebz, the Zone 2 has a separate amplifiers, so I guess it's more similar to bi-amp rather than bi-wire.

Any input on what would be better?

BTW my front speakers are Polk Monitor 70's and my rears are Monitor 40s.

Thanks,
Michael
Click to expand...


It wont make a difference if you bi-wire. I bi-wired my Monitor 60's and while there is a slight difference its not enough to make me do it again. Since my setup wont allow 7.1 right now it doesnt matter. When I move this upcoming August I will be doing 7.1 w/ CS1 center, 60's in the front, R50's for sides and Monitor 40's for the surrounds and a SVS PB12+ su.

It is still a bi-wire (I have an Integra reciever which is just high end Onkyo). You just use different channels of the same amp/powersupply. As you stated you need 2 diff amps to be bi-amped. I would say if you do bi-amp go with a Emotiva 3 channel amp for your fronts/center. Your surrounds in a 5.1 or 7.1 setup dont draw that much power
 
Last edited:
Amplifying the tweeter and midwoofer drive signals separately effectively lets you bypass the speaker's crossover circuit. If it was a substantial limiting factor and if the "external crossover" is a substantial improvement over the internal circuit, then you can see improvements.

Very often, people just hook it up because it's there without paying much attention to what's actually happening. This means that many "it does nothing" responses could be because there wasn't a large quality difference between the internal crossover and whatever they tried to amp it with...or for that matter, someone left the bridge connectors attached.
 
ashmedai said:
Amplifying the tweeter and midwoofer drive signals separately effectively lets you bypass the speaker's crossover circuit. If it was a substantial limiting factor and if the "external crossover" is a substantial improvement over the internal circuit, then you can see improvements.

Very often, people just hook it up because it's there without paying much attention to what's actually happening. This means that many "it does nothing" responses could be because there wasn't a large quality difference between the internal crossover and whatever they tried to amp it with...or for that matter, someone left the bridge connectors attached.
Click to expand...

Thing is, with regular passive speakers you can't bypass the internal crossover. You'll note that there's two binding posts, connected with a bridge. That means the crossover is past those binding posts (implemented as a high pass on one, a low pass on the other). So you can't bypass it. To do that, you'd have to open the speakers up and rip out the crossover circuit.

However after doing that, you'd then need to implement your own small signal crossover that you place before the amps, sending a full range signal to both would be a disaster. Also the crossover can't be arbitrary, if it is to sound good, it needs to mimic the design of the passive one you removed.

Converting passive speakers to active is technically possible, but a major task. Just removing the bridge and hooking up an amp to each set of binding posts does not do that. You still have the passive crossover in place, you've changed nothing other than increasing the total amount of amplification available to the speakers.
 
Yeah, unless someone bothered to put a transistor on the line to cut it if you're using both ports. In which case it becomes a design issue (the fault case would indeed act to mostly isolate the power draw of either half, which is relatively boring with efficient speakers and a good amp).
 
ashmedai said:
Yeah, unless someone bothered to put a transistor on the line to cut it if you're using both ports. In which case it becomes a design issue (the fault case would indeed act to mostly isolate the power draw of either half, which is relatively boring with efficient speakers and a good amp).
Click to expand...

I doubt you'd ever see that. You run the risk of someone biamping and not running a crossover (when you have a receiver biamp, it doesn't) and burning out the tweeter. More or less, biamping is worthless as an end user. If you bought active speakers, well then they have whatever amps they have. They'll be biamped if the maker wanted them to be. If you bought passive speakers, then don't biamp, it's a waste of money. Just use a single amp of sufficient power.
 
Sycraft said:
I doubt you'd ever see that. You run the risk of someone biamping and not running a crossover (when you have a receiver biamp, it doesn't) and burning out the tweeter. More or less, biamping is worthless as an end user. If you bought active speakers, well then they have whatever amps they have. They'll be biamped if the maker wanted them to be. If you bought passive speakers, then don't biamp, it's a waste of money. Just use a single amp of sufficient power.
Click to expand...

Hmm. Will a low-frequency signal actually damage the tweeter? If so, I wonder how well a simple high-pass filter would work...

Damn it, I need to get a good book on speaker design and audio electronics.

audio thug said:
Check out Lie No. 7 of Peter Aczel's article, "The Ten Biggest Lies in Audio".

http://www.theaudiocritic.com/downloads/article_1.pdf

It's an excellent read. Hopefully all newbies read it before they fall for snake oil (of which there is no shortage of in the audio world).
Click to expand...

Started scanning it, turns out the author is an idiot. That, or dishonest and serving an agenda - but I'll go for an idiot with minimal knowledge of electronics.

Didn't read much more than that, since there wasn't reason to after determining that the information was inaccurate. There are a lot of myths in audio...and others like burn-in that have enough gotchas that they might as well be. An article with a good overview would be useful to show around - unfortunately, this isn't the one.

As for the “tube sound,” there are
two possibilities: (1) It’s a figment of
the deluded audiophile’s imagination,
or (2) it’s a deliberate coloration introduced
by the manufacturer to appeal
to corrupted tastes, in which case a
solid-state design could easily mimic
the sound if the designer were perverse
enough to want it that way.
Click to expand...
 
Minimal knowledge of electronics? Have you read his reviews? Any piece of equipment he reviews undergoes a battery of objective measurements that I do not often see from any other audio publication. He knows what he is talking about. I wouldn't be surprised if he has an EE degree.

What about his stance on tubes do you find contentious?
 
audio thug said:
Minimal knowledge of electronics?
Click to expand...

If the guy can't figure out something that 10 minutes with an oscilloscope or spectrum analyzer would tell you...much less, ears to hear and some brief experimentation...

Someone who claims "all tube coloration is your imagination or the manufacturer trying to deceive you" either has no idea what they're talking about, or has some reason to want to deceive you themselves. You can even take the same amp and put one set of tubes in to get minimal coloration, then another to get strong coloration. What is it if not an electronic property of the tube you changed out, black magic?
 
Coloration as in the presence of 2nd-order harmonic distortion (never mind the fact that it is 'pleasing' to the ear)? I'm not an electrical engineer, so bear with me. Why is it a good thing? Don't you think that distortion is an enemy to high fidelity?

Solid state amps can power transducers without audible distortion, at lower cost, more reliability, and more efficiency. What exactly makes tube amps worth it?
 
Some types of distortion are bad, some can be good. Distortion is what distinguishes real instruments in the hands of human players from a simple computer-synthesized recording of the same sequence of notes. Tubes often also have a strong time-dependent component which can be interesting.

SS does many things better or more easily than tubes, and they can be smaller, waste less energy as heat, don't require heating to work, have simpler power requirements, are cheaper, are easier to manufacture in bulk...which is why people run around with iPods using transistors instead of vacuum tubes. But the two things are not identical, and anyone that says they are either has no clue what they're talking about or is lying. I prefer to believe people are just ignorant since it's no sin not to know any given thing - everyone is at that point at some time.
 
You make good points. But at the risk of delving into a philosophical argument, don't you think that any kind of 'distortion' is best decided IN the recording, and amplifier stages should be left alone with the goal of just amplification?

For example, I believe that frequency shaping with a tone control (or other hardware/software device) to user preference is just fine, but I don't think that this should be the job of an ideal amplifier.

What about the rest of his article? Do you believe in the effectiveness of cables, CD treatment, power conditioners, or to get to the matter at hand, biwiring?
 
ashmedai said:
Hmm. Will a low-frequency signal actually damage the tweeter? If so, I wonder how well a simple high-pass filter would work...
Click to expand...

Easily. It isn't the frequency that does the damage though, it's the power. Our audio signals contain much, MUCH more bass than treble. This is a combination of two things:

1) You have to more more air to generate the bigass bass waves, as such it takes more power to produce equal SPL.

2) Humans hear treble much better than bass. You can look at the graph that is generally referenced for this kind of thing but what you can see is that for bass ot sound equally loud, it often has to be 30dB or more than the treble.

Ok well this means that you send a whole lot more power to bass drivers. Now the reason this becomes a problem with a tweeter is because it doesn't have a lot of wire, nor a lot of heat dissipation capability. You send a ton of power to it, it'll melt the voice coil and screw up the tweeter.

This is why driving an amp to hard clipping kills tweeters. High harmonic distortion implies lots of high order harmonics implies lots of power to the tweeter.

Yes, a high pass filter would solve the problem nicely. That is, in fact, what a crossover is on a two way speaker. A high pass filter is placed on the tweeter, a lowpass filter is placed on the woofer. They are balanced such that the drivers don't hit resonant frequencies and the change is smooth.

So you can biamp passive speakers no problem, the crossover remains in place and protects the drivers. However you gain little to nothing from it. If you want to rip out the crossover, well then you need to implement your own. You can design one with small signal stuff like opamps, or you can implement one in a DSP like this. However you'd better have one, and if you want it to sound good, it has to match the drivers and enclosure and such properly. Just amping the drivers and feeding them all a full range signal will sound like crap, and will zorch your tweeters.

Loudspeaker design isn't all that easy. If you want to toy with it, it can be a neat project and there are lots of resources including calculators and the like. However, do it by purchasing cheap drivers and building your own. Don't take apart expensive speakers and figure that you can hook things up to make them better, at least until you know what you are doing.

If you aren't big on electronics (and woodworking to an extent) better to just buy the speakers you want. Home theater ones are almost always passive, studio ones are almost always active. Most active ones are bi or tri amped as appropriate. If you want good, far field, 3-way, active monitors, you can check out Genelec.
 
Sycraft said:
It isn't the frequency that does the damage though, it's the power.
Click to expand...

Good point. Without testing, I'll take your assertion that it would pop like a 100mA fuse in a 20A socket.

audio thug said:
You make good points. But at the risk of delving into a philosophical argument, don't you think that any kind of 'distortion' is best decided IN the recording, and amplifier stages should be left alone with the goal of just amplification?
Click to expand...

Naively, yes. For your standard iPod user that doesn't bother to get rid of the stock earbuds because they're white and match the advertising, probably. For someone dipping into high grade home audio or who just wants and doesn't mind taking more control, no.

Distortion is lost data...if you tell the circuit to produce voltage v at time t, it will try to do so, with no knowledge of what part of what factors contributed how much to that value. If I have a relatively neutral recording, I can mix it to my taste or I can play it on different equipment and get numerous interesting but distinct results. If it is highly colored to begin with, my options are much more limited.

I very much like being able to listen to a song on one set of equipment, then again on equipment that gives me a different presentation. It's a bit like if two singers performed the same song - they can both be good, but different elements of either performance will stand out, and you can get more out of it than if you only ever listen to one interpretation.

audio thug said:
What about the rest of his article? Do you believe in the effectiveness of cables, CD treatment, power conditioners, or to get to the matter at hand, biwiring?
Click to expand...

Cables have an effect. In the ideal case, the effect should be zero, and if properly done it should approach a reasonable approximation of zero effect. Increasing cable length greatly increases the likelihood of this becoming a meaningful factor. BUT you do not need solid gold extra pure single-crystal cables produced in orbit while under a hard vacuum - WTF - all you need is decent wire of sufficient gauge for the job. 18 gauge is usually fine for shortish runs. I like to use 12 gauge which is still cheap and the overkill does no harm, it just makes it a better approximation of the ideal case. Audible difference between that and the time I had them hooked up using a cut-off extension cable? About zero. He is mostly accurate here but pushes it a little far - for one, sometimes cheap cables are some retarded thickness e.g. 28 gauge that you really shouldn't be using for speakers. You can get cables that do the job cheaply, but not all cheap cables are any good. There is also the issue of connector quality - cheap cables use cheap connectors, which will not last as well as a slightly more expensive and better chosen part. If you're not just using bare wire.

Don't know that I've ever heard of this CD treatment thing. If you can get a rip in EAC that checks out with high accuracy, that's all there is to reading a CD. The only treatment I might worry about is to clean it or try and compensate for scratches - which quite clearly can interfere with reading the data out. Once you have an accurate digital stream, it looks exactly like any other accurate copy of that same data.

Amplifiers which take AC power as input, and many which take power from a DC adapter rather than from batteries, include some degree of circuitry devoted to getting a reliable and clean supply of power. Depending on how well you want to do this and how noisy a source you need to deal with, this can easily run into thousands of dollars just to get the relevant parts. Transformers in particular are fucking expensive. There are ways to do this cheaply, and you make varying degrees of compromises. However, this guy is effectively claiming that ANY power handling circuit is as good as an ideal version - which is bullshit. Of course there are differences, otherwise we could get a first-year EE student to design one and then use that design for every power circuit ever. Additionally, it does help to have a slightly higher gauge cable for the power - your standard universal AC cable can be a little thin. A thicker gauge version will cost you all of about $4 off Monoprice. Does a power conditioner have an effect on your audio? It can, but it depends on the relative effectiveness of the built-in circuit versus the external conditioner, and it is almost always the last thing worth considering. See AMB's or Tangent's site for designs and relevant discussions here.

Regarding biwiring, he's wrong in a way that is potentially harmful. Biwiring doesn't do nothing. As anyone with any knowledge of basic circuit analysis at all should be able to tell you, it halves the resistance (one wire vs. two wires) - which should have been very low anyway, and therefore shouldn't do crap unless you were using wires that are too small for the length of run involved, in which case the intelligent thing to do would have been to buy a spool of lower-gauge speaker wire. It also creates a current loop, which is not particularly good. It may do nothing, or it may make your system do seriously weird shit. Regardless, you shouldn't do it - but again, he goes too far.

Basically, this guy is like the people that tell you that taking a puff of marijuana will turn you into a terrorist. He makes some fairly good points but exaggerates to the point of inaccuracy in trying to support them, while on other points he's just wrong.
 
My threads gettin' blown up yo.

I guess I never would have thought to get all answers pointing to 7.1. No one stood up for bi-amping.

Now with that being said, can someone explain why two separate amplifiers must be used for bi-amping.

The Onkyo has 7 discrete amplifiers, one for each channel. I would assume the amplifier is also a band pass filter, although since there is a method of choosing "bi-amp" on the menu, this could be easily switched internally from a band pass to a discrete high and low pass filter.

Now, if I choose Bi-amp, in theory the woofer driving amplifier will be a low pass filter. What is the frequency cut off? Technically speaking Wc should be ~180hz right?

Any other EE's here should be able to agree with this. Besides getting a 2nd order derived from a single op-amp, when we(rarely) need a filter >2nd order, we cascade the filters. If we assume a simple Buttersworth filter design, the signal gain should be much more accurate to what we want. Less of a peak at Wo, and a steeper cutoff to Wc.

Same goes for the high pass.

If you cascade a low pass into a band pass, youll get something looking very similar to just passing it through a low pass.

So technically I see why bi-amping, even with a single amp should be possible, and theoretically better.

Now going on to what illgiveyoumortallity said:

What you said I can interpret two ways, and I take no offense to either.
A) bi-amping(wiring) is useless and Im not going to hear any difference in speaker XXX
B) or Monitor 70's arnt high quality enough speakers to notice the difference with the bi amp

Thanks,
Michael
 
If you take two amplifiers and put them in the same box, you still have two amplifiers (assuming you don't limit them meaningfully by feeding both off the same power cord / power filtering circuit / etc.).

Crossover frequencies are generally near 100Hz and 2.2kHz (sub-mid and mid-tweet respectively).

A bi-amp setup is something that's better in the ideal case but generally useless in practice. Speakers don't draw infinite energy, so there's usually not a reason to go one amp - one driver.
 
Crossover frequencies actually vary wildly. It depends on the size of the enclosure, the nature of the enclosure (sealed, vented, etc), the drivers chosen, the number of different drivers and so on.

For example my B&W 604s I used to have were 3 way speakers, meaning they have distinct woofers, mids, and tweeters. They were crossed at 450Hz, and at 4kHz. Because they were 3 way the tweeter could be crossed pretty high. Also, it was fairly necessary because it was a metal tweeter, which has a much higher resonant frequency.

My current MTS-01 speakers are different. They are only 2.5 way, so the only crossover point is at 2kHz. Their soft dome tweeter can handle a much lower crossover, and the lack of dedicated midrange makes it more desirable to send more high frequency to the tweeter. The woofers then have a bit of a different configuration. One is sent the full range signal from 2kHz on down, the other is lowpassed at around 200Hz and only helps play the lower bass ranges.

Also with the crossovers the slope is important, that is to say how fast one transitions to another. It is not immediate. They are commonly 2nd to 4th order, meaning 12dB-24dB per octave, but some speakers use first order crossovers, and some higher order. Also they can use different ones on different speakers, to compliment the speakers' natural rolloff.

Crossover design is an incredibly complex part of speaker design. There are no hard and fast rules, it depends on so many factors. Now these are, for the most part, empirical, you can calculate it based off of the T/S parameters of your drivers and the enclosure they are in.

Thus the reason they don't let you switch off the crossovers and try it implement your own. Most people would do it wrong.
 
bi-wiring and bi-amping is different.

That being said, I think you should go for 7.1. Your receiver is plenty powerful for those front speakers.
 
ashmedai said:
Yeah, by near, I don't mean +/- 10Hz.
Click to expand...

Well you have to remember that at low frequencies, small frequency changes matter a lot. Frequency is logarithmic. So the difference between 100Hz and 200Hz is an entire octave, whereas the difference between 10,000Hz and 10,100Hz is minor.
 
You must log in or register to reply here.
Back
Top