What next for this developing HT setup?

[KeithS]

I'm an electrical engineer and built some bookshelf speakers 30 years ago, but on the topic of HT acoustics and equipment I know enough to know that it isn't just a matter of engineering the specs.

I bought a Denon AVR-X6200 (9.2, 11.2 w/external amps), so I'd have something to grow onto. I began with stereo and was very impressed with this receivers sound with two speakers so I moved on. Now I'm using four speakers in a 4.0 arrangement using my four Infinity Overture 3 speakers. The O3 is a 20-22kHz stereo grade tower with 1 tweeter, two 5.5" midrange, and a 200W amplifier driving 4x6.5" woofers.

With 800W of base power driving 16 6.5 inch speakers this 4.0 setup is spectacular (on my HT newbie movie watching scale) having watched American Sniper, San Andreas, and a number of less noteworthy HD DD movies on a new 4K Samsung TV. I have a 14x16 carpeted theater room and listen at about, say 75-80dB (not terribly loud), but it still rattles objects on metal shelves in my workshop, below.

My question is, what next? CNet says I may not get much adding a center speaker since have very capable fronts. I already have decent low frequency power, but far as LF theater enjoyment goes I don't know how far improvement goes.

So, I could use some advice. Where am I likely to get the most improvement? Maybe the .1 (how about a 15" Dayton Titanic ported DIY?). Maybe a center speaker, but what should I use that will be on par with the quality of my O3s? Maybe neither and the most improvemnt can be had by adding two more surround speakers.

Comments?

 

[BoredSysAdmin]

the issue is front 3 speakers really should be perfect match - ie: for your excellent, but vintage speaker, you'd have to find a matching vintage center.
I'm not 100% sure, but I think that CC3 or Compositions Overture OVTR-1 should work, but don't take my word for it - I'm not an expert
http://www.ebay.com/itm/Infinity-Non-Powered-Center-Speaker-CC-3-type-332142-/271712150234?hash=item3f434e62da:g:cCYAAOSwnDxUkkvr
http://www.ebay.com/itm/Pair-Of-Infinity-Compositions-Overture-OVTR-1-Type-331252-Powered-Speakers-Nice-/262105351222?hash=item3d06b24436

But biggest change you need is as you guessed is sub(s) - It's not about rattling metal objects, but a) very low bass which modern movies are good at using very often and b) by not letting your other speakers play low bass - it allows them to play a bit cleaner. Your fancy Hi-End Denon auto room calibration should be able to tune it correctly.

As for specific: Well, PE modeled this sub in ported box:

• Vented Volume5.46 ft.³
• Vented F3 21 Hz

Nice, but possibly could model it for you with more info - specifically model for low Q and correct port volume/length

If DIY is not you thing and your room is fairly small - this sub should do the trick:
http://www.hsuresearch.com/products/vtf-2mk4.html

 

[KeithS]

I cannot post a reply. I am told I can't post email or links but the reply had none.

 

[KeithS]

Obviously I was able to post after waiting a while.

Yea, I tried using some old Sony K-Mart speakers in the center and promptly switched back in disgust - it was awful. There are Infinity O3s and parts around, but in short supply so sellers want top dollar. I'm thinking that the best center speaker may be an O3 speaker, crossover, and dialed back bass amp in a custom center speaker cabinet. Does that make sense?

PE (who is PE?) modeled which sub? The 15" Dayton Titanic Mk IV I mentioned?

No, no problem with DIY. It may be a kind of neurosis, but I think I need a science and electronics projects to be happy in life. On the other hand, we can't DIY everything, so prioritizing is necessary too. The priority for DIY is when you get a big improvement or much lower cost. In subs, it looks like DIY can cost you more.

I like your HSU speaker suggestion, a lot. I've been considering this exact sub and even had the HSU specifications page open on my desktop when I read your reply to my post. My apprehension has been that I don't want loud base, I want good quality authentic hi-fidelity sound with the option to make it loud if it suits me. I don't want to over-amp the base just for visceral thrills. I really like how this sub reaches down into the teens, but was worried that it would be too much with the O3s. Tonight I'm thinking the VTF-02mk4 will be my next purchase, but I only need a nudge to change my mind and go DIY.

-KeithS

 

[Swerd]

My question is, what next? CNet says I may not get much adding a center speaker since have very capable fronts. I already have decent low frequency power, but far as LF theater enjoyment goes I don't know how far improvement goes.

So, I could use some advice. Where am I likely to get the most improvement? Maybe the .1 (how about a 15" Dayton Titanic ported DIY?). Maybe a center speaker, but what should I use that will be on par with the quality of my O3s? Maybe neither and the most improvemnt can be had by adding two more surround speakers.

CNet is wrong about a center channel speaker. In my experience, a good center channel speaker is important for movies or TV, probably much more important than the rear channel speakers. Multi-channel formats usually have only the dialog in the center channel. A speaker that reproduces voices clearly without any added bass emphasis (low Q) that also has wide mid range dispersion, is important. Any good AV receiver, such as your Denon, also allows you to separately adjust each speaker level so you have complete control over hearing the dialog. Sometimes movies don't get this mix right, and changing only the master volume will never solve that problem.

Of course, all this depends not only on what speakers you have (I haven't heard the Infinity Overture 3), but also their placement relative to a TV screen, and where the listeners sit. Yes, if you sit directly in the center, the two left & right front speakers can create a "phantom" center channel, but as soon as you move off-center that can disappear.

I agree about BSA about a sub woofer, and despite the fact that your Infinity speakers probably don't lack bass, 6.5" speakers probably can't reach a low as a proper sub woofer. PE is Parts Express, the web site that sells DIY drivers such as their rather good house brand, Dayton.

 

[KeithS]

The advice I've received makes sense so, I've concluded that a center speaker is needed. My default path now is to watch Ebay and Craig's list until until I can find a 5th Infinity Compositions Overture 3 for this purpose. If I can find one with a beat up enclosure so much the better. I can remodel the enclosure to be suitable for horizontal mounting.

I've been toying with the idea of building a subwoofer based on a variety of sub-woofer drivers at Parts Express including the Dayton Audio Titanic Mk IV and UltraMax 12" or 15". I started playing with the simulations then ran across the SI HT18 started drilling down in to a design with it, then decided I might be going off the rails. I don't listen that loud and my room isn't that big. I've got a kitchen remodel to do, so maybe I should save some time an money and pick up the vtf-2 MK4, and if that's a huge improvement maybe another one in a few months. With the LF roll-off of the one-port configuration in the teens, this speaker seems very attractive. My biggest worry is that I'll like it and want more than the 250W continous output this speaker provides. My four O3's are specified at 200W and 3dB down at 20Hz, but the small speakers won't provide the SPL/Watt that a larger speaker or two would offer.

Indecision, indecision. So much to do, and I probably only have 2-3 decades left.

-KeithS

 

[Swerd]

The advice I've received makes sense so, I've concluded that a center speaker is needed. My default path now is to watch Ebay and Craig's list until until I can find a 5th Infinity Compositions Overture 3 for this purpose. If I can find one with a beat up enclosure so much the better. I can remodel the enclosure to be suitable for horizontal mounting.

Although matching all 3 front speakers is often advised for people buying new speakers, you aren't really limited to an exact match. As long as the center speaker does voices clearly (no added bass to overemphasize male voices) and has mid range dispersion as good as or better than your left & right speakers, you'll do well. I originally used old JBL speakers I had owned since the 1970s in my first 5 channel rig, and I found that NHT center channel speakers were excellent even though they were not a match for my left & right speakers. They actually out performed them in the mid range. You immediately noticed it when you used that cheap and under performing center channel speaker. It probably sounded muddy and muted compared to your O3s. But if a center speaker actually out performs the left & right (in the mid range) it isn't trouble at all.

Bass in a center speaker is not needed, in DVD & BluRay movies only dialog is in the center channel. As a result, a center channel speaker doesn't require a large cabinet, which can create trouble as it should be as near as possible to the TV screen. You might look for used Infinity or NHT center channel speakers. They often come as MTM designs with two 5.25" or 6.5" mid woofers and a 1" dome tweeter. They are closed cabinets – no port to worry about.

I've been toying with the idea of building a subwoofer based on a variety of sub-woofer drivers at Parts Express including the Dayton Audio Titanic Mk IV and UltraMax 12" or 15". I started playing with the simulations then ran across the SI HT18 started drilling down in to a design with it, then decided I might be going off the rails. I don't listen that loud and my room isn't that big. I've got a kitchen remodel to do, so maybe I should save some time an money and pick up the vtf-2 MK4, and if that's a huge improvement maybe another one in a few months. With the LF roll-off of the one-port configuration in the teens, this speaker seems very attractive. My biggest worry is that I'll like it and want more than the 250W continous output this speaker provides. My four O3's are specified at 200W and 3dB down at 20Hz, but the small speakers won't provide the SPL/Watt that a larger speaker or two would offer.

If those Infinity O3s can really provide an F3 at 20 Hz, that is better than many sub woofers. In all honesty, it isn't terribly expensive ($500-600 DIY) to get a 12" sub with an F3 of 25 Hz, but you will double that cost to get a true F3 of 20 Hz.

 

[KeithS]

Swerd, you are giving me exactly the sort of direction I was hoping for.

I looked at two Infinity center speakers in the $150 range (new), which people on audio sites hated. Amazon's top rated is the $119 Polk audio CS10, which other reviewers pan.

Top-ten-reviews rated the Yamaha NS-C310 very highly but for reasons that don't matter to me, such as a high frequency roll-off of 45kHz. None of my media have sampling faster than 44kHz, which means they can't reproduce anything over 22kHz and I can't hear anything whatsoever above 18kHz, anyway. Also, just out of curiosity, is it an oxymoron to say "2.5 inch woofer"?

I inherited two pair of O3s from my dad who passed away about a year ago. I knew they sold for $2200/pair and had high expectations, but three of them sounded absolutely terrible. Because one seemed good I investigated and found:
1) One tweeter was blown from each pair (this turns out to be common with O3s)
2) Both tweeters in one pair were low quality substitutes that sounded pretty bad,
3) In one the crossover connections for the tweeter and a mid-range were swapped.

The speaker with the swapped connections sounded horribly shrill and the X displacement of the missconnected mid-range was obviously much less than the other. Someone tried to fix the shrill over-amped tweeter by stuffing both mid-range speakers with damping. I concluded that my dad, who played classical music at modest volumes, did not get either set of speakers new.

Incidentally, I have a suspicion that the many O3 owners with blow tweeters may be the victims of an Infinity manufacturing quality control failure. The crossover connectors are polarity keyed but interchangable with labels HF and MF which are blurry enough to look the same. There is an Infinity service bulletin that calls to replace a blown 50V series capacitor (C5) in the highpass filter feeding the tweeter with an identical 100V part. Both the blown tweeter and blown capacitor would be likely to occur with the connections swapped as I found them.

I have a good quality microphone with calibration data and sufficient BW. I'm interested to see if the O3s actually achieve the 20Hz 3dB rolloff Infinity claims. I could be wrong, but from what I've seen this would be remarkable as an efficient flat response down to 20Hz isn't easy to achieve even using 12"-15 sub-woofers.

I definitely don't have golden ears, my restored O3s sound better to me than anything I've owned previously - maybe better than anything I've actually listened to. I tried using two 6 Ohm Sony SSD-302s (very cheap) individually and connected in series at 12 Ohms and I hate the sound at the Audyessy calibrated levels and if I turn them down. Their sound is thin and tinny and detracts from the setup, which sounds better without them. I don't want to buy a center speaker and get the same result, but I live in rural Maine where the nearest reasonably large audio store is a 45 minute drive. I could use some the some recommendations from people who can recognize good sound.

-Keith

 

[Swerd]

Keith - I'm glad my opinions make sense for your situation . Because you are far away from any audio store, buying direct from Amazon or a manufacturer is probably your best option. They should have a reasonable return policy (30 days?). You mentioned some Infinity and a Polk center speaker available at Amazon. I'm not familiar with either of those, but those prices suggest they might not be good enough for you. Remember that both Infinity and Polk are not the companies they once were. Both have been sold and are under completely different management.

I do know from experience that NHT makes excellent sounding, modestly priced, products, that are known for their overall neutral sound, neither bass heavy, nor too bright. I had owned an NHT SuperCenter, which is the equivalent to the SuperCenter 2.1 that now sells new for $200. It's easy to dismiss those two 4.5" woofers as too small to take seriously, they only go down to 85 Hz for a reason, they are meant to only work for human voices. This also gives them the advantage of being small. They are honestly rated at 86 dB sensitivity which may be less sensitive than your Infinity speakers, but AVRs can deal with that.

NHT now sells Internet Direct. Amazon also carries them at the same prices. NHT is in California, so check to see whose shipping costs might be better for you.

Your experience with the blown tweeters and swapped connections on those Infinity O3s is interesting. I don't know of many tweeters that can survive long when fed mid range signals. Were you able to find replacement tweeters for them?

I have a good quality microphone with calibration data and sufficient BW. I'm interested to see if the O3s actually achieve the 20Hz 3dB rolloff Infinity claims. I could be wrong, but from what I've seen this would be remarkable as an efficient flat response down to 20Hz isn't easy to achieve even using 12"-15 sub-woofers.

It is difficult to get meaningful frequency response measurements of loud speakers for the frequencies below roughly 200 to 250 Hz. Those wavelengths are in the same ball park as your room dimensions. 100 Hz has a wavelength of about 11 feet (speed of sound is 1125 feet/second), 50 Hz is 22 feet, etc. As a result, direct sound from the speaker can arrive at a measuring microphone at nearly the same time as sound reflected from walls, ceiling and floor, but out of phase with each other. If you move the speaker or the microphone by a few inches, you can significantly change the measured frequency response curve.

So don't be surprised by or shocked at your results. That's why anechoic rooms are used.

 

[KeithS]

Remember that both Infinity and Polk are not the companies they once were. Both have been sold and are under completely different management.

Harmon Kardon too. H-K used to be top rated due to the engineering, but plain looking and lacking the flashy illuminated displays of the competition.

In part because I live in the middle of nowhere, I am a very active Amazon Prime member. I used to live in San Diego and sometimes miss the commercialism and availability of just about everything, but rural living and rural people are much better company and politically they think for themselves.

I do know from experience that NHT makes excellent sounding, modestly priced, products, that are known for their overall neutral sound, neither bass heavy, nor too bright. I had owned an NHT SuperCenter, which is the equivalent to the SuperCenter 2.1 that now sells new for $200.

I had not heard of NHT before this, but have not been active in audio. I will look into them.

It's easy to dismiss those two 4.5" woofers as too small to take seriously, they only go down to 85 Hz for a reason, they are meant to only work for human voices. This also gives them the advantage of being small. They are honestly rated at 86 dB sensitivity which may be less sensitive than your Infinity speakers, but AVRs can deal with that.

NHT now sells Internet Direct. Amazon also carries them at the same prices. NHT is in California, so check to see whose shipping costs might be better for you.

Amazon - NHT SuperCenter 2.1 is $160, no tax, free shipping.
Specifications
System Type: 2-way acoustic suspension
Driver Complement: Two 4.5" woofers, 1" soft dome tweeter, video shielded
Crossover: 2.2KHz, 6dB/octave HP & 12dB/octave LP
Frequency Response: 85Hz - 25Hz, +/-3dB [sic. - probably s/b 25kHz]
Sensitivity: 86dB
Impedance: 8 ohms
Recommended Amplifier Power: 15W min., 150W max.

You are right, the sensitivity is a bit low. For my Denon AVR-X6200 (145W/2Ch, 8 Ohms, 20Hz-20kHz) I should probably use a midrange rated at 200W or more. The 2C and 3C handle power more in keeping with my amplifier's capability and running the center well below its max will probably sound better.

I wonder why the sensitivity is that low on this company's center speaker line. I don't know what goes into sensitivity. A 5dB difference is big, though it can be compensated by the speaker calibration.

Your experience with the blown tweeters and swapped connections on those Infinity O3s is interesting. I don't know of many tweeters that can survive long when fed mid range signals. Were you able to find replacement tweeters for them?

I found three new Infinity O3 neodymium tweeters that I paid through the nose for ($70/each). It was worth it. All three speakers sound exactly the same now and it is amazing. My father in law is visiting and is commenting on the sound of the music when he never paid any attention to it before.

It is difficult to get meaningful frequency response measurements of loud speakers for the frequencies below roughly 200 to 250 Hz. Those wavelengths are in the same ball park as your room dimensions. 100 Hz has a wavelength of about 11 feet (speed of sound is 1125 feet/second), 50 Hz is 22 feet, etc. As a result, direct sound from the speaker can arrive at a measuring microphone at nearly the same time as sound reflected from walls, ceiling and floor, but out of phase with each other. If you move the speaker or the microphone by a few inches, you can significantly change the measured frequency response curve.

I was planning to test outdoors to eliminate the reflected sound - one advantage of rural living is no neighboring houses or structures. I have three 100 foot AWG 10 extension cords so I should be able to get a half second of sound measurements before the reflected waves return.

So don't be surprised by or shocked at your results. That's why anechoic rooms are used.

I have access to an anechoic chamber used for radiated emissions testing, but I don't think I'll need it unless the weather gets too cold before I get around to testing.

-KeithS

 

[Swerd]

Good luck moving those large speakers outside .

I missed the $160 SuperCenter on Amazon. Not bad.

I had not heard of NHT before this, but have not been active in audio. I will look into them.

You are right, the sensitivity is a bit low. For my Denon AVR-X6200 (145W/2Ch, 8 Ohms, 20Hz-20kHz) I should probably use a midrange rated at 200W or more. The 2C and 3C handle power more in keeping with my amplifier's capability and running the center well below its max will probably sound better.

I wonder why the sensitivity is that low on this company's center speaker line. I don't know what goes into sensitivity. A 5dB difference is big, though it can be compensated by the speaker calibration.

Sensitivity is supposed to measured in a standard way, a test mike 1 meter away with 2.83 volts pink noise signal delivered to the speaker, but it is often exaggerated for marketing purposes. So it can be difficult to compare different brand speakers by sensitivity alone. I have a hard time believing any home speaker rated at more than 90 dB. I suspect that 86 dB for that NHT center speaker is more honest than most. When I owned mine, it was less sensitive than my left & right speakers, but after I adjusted the different channel levels, it was fine.

What matters more is how well the speaker disperses the dialog sound. Those small 4.5" mid woofers may be less sensitive, but their smaller diameter allows them to disperse mid range frequencies over a wider angle than larger diameter drivers. As a woofer produces sound at a wavelength similar to its diameter or smaller, it beams the sound over a much narrower angle. At their crossover frequency of 2200 Hz the wavelength is 0.5 feet. And because the crossover has a shallow roll off, 12 dB/octave low pass slope, those mid woofers will be audible an octave above the crossover point.

Good luck with your center speaker search. Let us know what you end up with.