Need advice for rear surround speakers


  #1  
Old 01-28-03, 05:10 PM
stanky1
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Need advice for rear surround speakers

I am looking to complete my home theater system by adding the rear speakers. The surround receiver is a Teac AG-V8500. The surround output power (0.5% THD, 1 kHz, 8 ohms) is 50 watts each for the rear speakers

As I understand it, rear speakers supply less than 10% of the sound. Therefore, it doesn't seem to make sense to spend a bundle on rear speakers, right?

Am I wasting my money to buy something like Polk Audio RC551? Any recommendations or minimum specs?
 
  #2  
Old 01-29-03, 04:20 AM
RickJ6956
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The original Prologic systems limited the bandwidth of the rear channel to 4kHz. There wasn't any real need for full-range speakers. But today's 5.1 and 7.1 discrete systems are full-range, so the better the rear speakers, the better the overall sound.

The Polks may be overkill. IMO, a good mid-line pair of two-ways with a 5" or 6" woofer will do it. If you hang 'em from the ceiling, hang 'em upside down (with the tweeter on the bottom).
 
  #3  
Old 01-29-03, 09:16 PM
stanky1
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I was thinking of a flush mount in-ceiling speaker. Do you have any recommendations?
 
  #4  
Old 01-31-03, 07:43 AM
RickJ6956
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I never liked the ceiling-mount speakers. Even the two-way concentrics sound cheesy. When I was installing, I preferred to use cabinet-style speakers that fit between the structural members in the ceiling. Cover with a custom grille fabric that matches the paint. Added benefit: You can aim the cabinets toward the listening position.
 
  #5  
Old 02-02-03, 01:36 PM
dnewma04
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Originally posted by RickJ6956

The Polks may be overkill. IMO, a good mid-line pair of two-ways with a 5" or 6" woofer will do it. If you hang 'em from the ceiling, hang 'em upside down (with the tweeter on the bottom).
I agree that the polks may be overkill, but I disagree with putting them upside down. First of all, the difference would be inaudible to most and second, having a tweeter under a mid tends to shift the phase upwards. Of course, that's probably making too much of a generalization, because there are certain crossovers that will counteract that. The simplest way I can put it is if you see a speaker with an angled baffle, the intention is to lineup the voice coils of the drivers on the vertical plane because if the front of the speakers are aligned, the phasing is generally tilted down.

Anyway, I'm rambling.

There are a couple of good choices if you are considering in walls and want to keep a tight budget. I would check into the Dayton in-walls from www.partsexpress.com . They sound a great deal better than I expected (I only heard the 6.5" two-ways) for a set of speakers that cost 40.00 a pair on sale. If you can afford to upgrade to the 8" three way version, I would recommend it.

Another option at the PE site is the BR-1. From all reports, it outperforms drivers many times its price. The only downfall is it is a kit.

Good luck!
 
  #6  
Old 02-02-03, 04:59 PM
stanky1
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Thanks for your help. The BR-1's don't appear to be an in-wall speaker. I don't think that I could mount a cabinet-style speaker in the ceiling and have it look very good. So I need to stick with the ones designed for in-ceiling placement.

What do you think of the DLS C-series 2-way (part #300-036) for $60/pair?

By the way, how do I tell if my receiver uses the old ProLogic vs newer 5.1 or 7.1? I bought it around 1997.
 
  #7  
Old 02-02-03, 07:40 PM
dnewma04
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Sorry, forgot to specify that the BR-1 was a cabinet style speaker.

THe DLS in-wall you mentioned was the Dayton in wall I had mentioned. For 60.00 a pair, you will not find a better sounding in-wall speaker.

If your receiver is from 97, it will be Dolby Pro-Logic.
 
  #8  
Old 02-03-03, 09:14 AM
RickJ6956
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I don't understand your use of the term "phasing". Please elaborate for me ...

dnewma04 wrote:

... I disagree with putting them upside down...
... the difference would be inaudible to most ...
Hi-frequency sound tends to travel in a straight line. The tweeters should therefore be mounted as close to ear level as possible. In a home with 7.5 or 8-foot ceilings it can make a huge difference on rear speakers. (This assumes that the speakers will be angled toward the listening position.) Also, placing the woofers up next to the ceiling can increase bass response by 1.5 to 3dB.

... having a tweeter under a mid tends to shift the phase upwards...
... there are certain crossovers that will counteract that...
There is no mid driver in a two-way speaker. Even then, I don't understand how phase has anything to do with it. All multi-driver cabinets have phase issues at or near the crossover points. The passive crossover is as guilty as the box design. Indeed, without phase cancellation, there would be no crossover points.

The simplest way I can put it is if you see a speaker with an angled baffle, the intention is to lineup the voice coils of the drivers on the vertical plane because if the front of the speakers are aligned ...
This is called time alignment, and its purpose is to make sure that the sound from each driver leaves the cabinet at the same time. It may have an affect on the sound quality of the speaker, but it does not seriously affect the angle of projection.

What you seem to be saying has more bearing on phase-aligning an array of speakers, like we see at concerts. Individual cabinets are stacked or grouped in such a way as to direct the sound to where it does the most good. For example, stacking 12" mid cabinets (pro sound reinforcement systems) decreases the vertical dispersion angle and allows the array to be aimed directly at the audience with little "bleed" into the ceiling or floor.


... because if the front of the speakers are aligned, the phasing is generally tilted down.
I don't understand your use of the term. In a standard two-way speaker, phase issues have very little bearing on projection angle. But even if it did, the speaker doesn't care if it's rightside up, upside down or sideways. It is firing into a 3-dimensional space regardless of its orientation -- with the same variance in projection angle. (That's why it's important to listen to the system when you aim the speakers.)

Phase is a result of the interactions of time and frequency on two or more waveforms. Now, phase problems in the speakers can cause cancellations in the sound field, but there is so much going on in the average living-room acoustic environment that the speakers are the least of our worries.

It seems that sound design has as many methods as there are people who listen to speakers. Physics aside, "good sound" is all opinion. I'd like to hear more from you. Good discussion.

-- RJ
 
  #9  
Old 02-03-03, 11:17 AM
dnewma04
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Hello Rick!

I don't have a lot of time to respond right now since I am at work, but I will respond when i get home tonight.



It seems like it could be an interesting discussion and I agree with most of your points.
 
  #10  
Old 02-04-03, 05:00 AM
dnewma04
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Originally posted by RickJ6956
I don't understand your use of the term "phasing". Please elaborate for me ...
What I was actually referring to, but trying to find a more simplistic term, was the zero delay plane.

[quote]
Hi-frequency sound tends to travel in a straight line. The tweeters should therefore be mounted as close to ear level as possible. In a home with 7.5 or 8-foot ceilings it can make a huge difference on rear speakers. (This assumes that the speakers will be angled toward the listening position.) Also, placing the woofers up next to the ceiling can increase bass response by 1.5 to 3dB. [quote]

If they are going to be angled, the matter of a few inches of change in the position of the tweeter would be marginal. I agree that you can get a boost in bass, but again, you will likely see close to the same amount of boost if the mid is 5" away from the wall.

There is no mid driver in a two-way speaker.
Semantics. When I say mid, i mean a driver that covers the midbass to midrange freq. It could be called a woofer in a two way, but that is really irrelevant.

This is called time alignment, and its purpose is to make sure that the sound from each driver leaves the cabinet at the same time. It may have an affect on the sound quality of the speaker, but it does not seriously affect the angle of projection.
It's sort of a subjective thing (SQ) so it's hard to place a value on it, but with even order crossovers, the ZDP will be at an angle perpendicular to the vertical plane between the voice coils. It could be argued that the difference would be insignificant.
[quote]
What you seem to be saying has more bearing on phase-aligning an array of speakers, like we see at concerts. Individual cabinets are stacked or grouped in such a way as to direct the sound to where it does the most good. For example, stacking 12" mid cabinets (pro sound reinforcement systems) decreases the vertical dispersion angle and allows the array to be aimed directly at the audience with little "bleed" into the ceiling or floor.[quote]

Not really what I was getting at, but what you are describing is very common in HT and does have some very good advantages.

In a standard two-way speaker, phase issues have very little bearing on projection angle. But even if it did, the speaker doesn't care if it's rightside up, upside down or sideways. It is firing into a 3-dimensional space regardless of its orientation -- with the same variance in projection angle. (That's why it's important to listen to the system when you aim the speakers.)
Again, when going for optimum alignments, it one could argue it does matter. Even crossovers will affect the output at certain angles. Odd order butterworth crossovers will cause + 15 degrees or - 15 degrees tilt of the radiation pattern, depending on the order and polarity.
Phase is a result of the interactions of time and frequency on two or more waveforms.
I can't disagree there.
Now, phase problems in the speakers can cause cancellations in the sound field, but there is so much going on in the average living-room acoustic environment that the speakers are the least of our worries.
I couldn't agree more. A perfectly flat anechoic response quickly goes to hell in most any listening environment. And with my initial response I was thinking of that when I recommend to align them with the tweeter on top. Everything is a trade off, and in my estimation, the probable radiation tilt would be what I would shoot for over the additional bass boost the mid would get. In a perfect world, he would be using dipolar rear speakers which would eliminate most of our disagreements.

It seems that sound design has as many methods as there are people who listen to speakers. Physics aside, "good sound" is all opinion. I'd like to hear more from you. Good discussion.

-- RJ
Again, I agree completely and look forward to your response. I'm no golden ear audiophool, but I do love to experiment with things. I have been doing DIY audio projects for years. Some good, some bad, most of the recent projects have been focused more on the unusual.

 
 

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