Jump to content

Center speaker


mace

Recommended Posts

While technically not a two channel question... I was wondering how to hook up a center channel with an amp with only left and right out. Is this possible??

I've read here that PWK design several center channel speakers for his corner horns. Was this done with a two channel amp?

Thanks!

Mace

Link to comment
Share on other sites

Check the operating manual to see if it is Bridgeable. Bridging usually involves changing some switches or wiring method which combines the power outputs for L/R channels to a single channel use. If possible, the instructions would state which Left or Right channel RCA out is used for signal output. Should also state which combination of Left and Right +/- Terminals are used for single speaker connection as well.

If the amp in question is not Bridgeable, you will need one that can be.

Wes

------------------

KLIPSCH IS MUSICf>

My Systems f>s>c>

This message has been edited by ShapeShifter on 08-10-2002 at 08:08 PM

Link to comment
Share on other sites

I did it the easy way; I bought a Dynaco QD-2 passive 5-channel "decoder". You input L & R channels from your two-channel amp or receiver, and it puts out a summed center channel, two surround channels and an unprocessed front pair. All at speaker level. Works great, with no dsp artifacts.

------------------

JDM

Link to comment
Share on other sites

Boy I bet that puts out some real Audiophile sound quality Smile.gifSmile.gif

------------------

Nos.gif

HH Scott 299 Amp

HH Scott LT-110B Tuner

HH Scott P-87 Turn Table

JVC JL-F50 Turn Table

Sony CDP-CA7ES CD Drive

1985 Walnut Heresey I W/Layne Audio Woofers

KSW-15 Subs>c>

Link to comment
Share on other sites

The Dynaco QD is the cheap and pure way to go. I've used them for over 30 years. Just found a copy of the old DynaQuad demo record in mint condition in Florida a while back. Musically not overwhelming, but the FR separation is nearly as good as DD5.1, and FAR more musical given the lack of processing.

Still consider it a shame Dynaco didn't have the clout to line up the big boys. Unless you had big bucks to spend, the 4 channel systems of the first era sounded AWFUL. PingPong stereo X 4 with a load of noise and artifacts. It would have changed the history of audio significantly. As it is, a mere footnote...but a footnote easily experienced for those who want both purity and depth as well in their music.

As to your original questions, the current QD is also the safest and cheapest way to derive a center channel I know of. Just remember you need a speaker equal or more efficient than the LR's since there is no gain in the circuit.

Dave

Link to comment
Share on other sites

I don't have the diagram here. I use three Radio Shack 70 volt line transformers as adders.

The L and R amp outputs of the two amps go to the 8 ohm inputs of two transformers. The 70 volt secondary windings are put in series to add, they feed the 70 volt input to the third tranformer. Then the 8 or 16 ohm output of the third gives you Left plus Right.

It takes some messing around with the taps to get the level correct. Still, it gives a good result.

Note though, that for this to work well, the center channel speaker has to be close in sensitivity to the flanking units.

It does increase the load on the amp a bit, but I've not had a problem.

There is another scheme (similar in principle) in a paper by John Ergle (sp?) which required rewiring of the output transformers of a tube amp.

Gil

Link to comment
Share on other sites

Hey Gil...any easy circuit for summing L+R at line level? While the QD is great for the rear channels, I'd prefer to use an amp with gain for the center in order to better match levels.

Dave

------------------

David A. Mallett

Come taste muh' Klipsch!

This message has been edited by Mallett on 08-13-2002 at 09:45 AM

Link to comment
Share on other sites

David--

If you do a search on this forum with the subject "center channel" and limit the search to articles written by Al Klappenberger (careful with the spelling), you'll find several threads written last year on how to construct a derived center channel from a line level output.

It's VERY simple to make: 2 or 3 resistors (depending on the version), 5 RCA female terminals, and a small project box will do it.

In those threads, you'll find lots of comments on deriving a center channel from the L and R channels by people who haven't tried it or haven't heard it, most of whom are concerned that it would smear the sound and upset stereo imaging. The people who have had actual experience with it, however, swear by it.

Adding a mono center channel to improve stereo imaging sounds crazy at first, but the principle behind it is simple and logical. Let's say there are a left and a right microphone in front of any sound source. If you added a third microphone midway between the other 2 microphones, its output would be a discreet third channel that contains sounds from the center, the L, and the R sides of the stage. The discreet third channel would give you better image localization. A derived center channel that sums the L and R channels sounds has exactly the same information as a discreet third channel and would give you the same improved imaging.

Just keep the level of the center channel about 6dB below the output of the L and R speakers for the best stereo imaging.

The concept of using a center channel for improved stereo has an impressive pedigree. It was based on pioneering audio experiments done on the stereo effect by Bell labs in the 1930's and used by Paul Klipsch in his own work.

Link to comment
Share on other sites

Doesn't sound crazy to me. I've a Cornwall between my 'horns. As explained above in this thread, it is driven through a Dynaco QD-2 at the moment. It helps a lot in my less than optimum dimension room. However, since I've a couple of amps around doing nothing I thought it might be interesting to be able to vary the volume of the center up some. I can turn it down now, but the effect is just there at max since it is a no gain circuit. I would like to test the idea that the Corny is just about 3 db too far below the 'horns to make a perfect passive match.

In fact I've sort of suspected that PWK felt the same way.

Hopefully, I'll settle this with a La Scala in the center in the not too distant future. In theory, I'd prefer the center be passive. We "2 channel" types just like to keep it simple.

Thanks, Gil, for the Dope from Hope. Has everything there for what I was looking for.

Hardhead: I note you are in the Dallas area. Would you be interested in the Dallas Area Klipsch Forum? Its pretty informal and we met here last. Next meeting is pretty soon at Jeff Savages house and promises to be butt kicken. I'll add you to the email loop if you are interested.

Dave

Link to comment
Share on other sites

Hmmm... so if I hook up a third speaker to the B outputs of my amp and wire the third speaker such that it would be 'mono' then I should get this center channel (albeit, not at -6 dB) when running A+B mode?? Or, is that L-R wiring recommended (Hafler circuit). I don't want to invest in a QD thingy right now, I'm just curious and want to play around with what I have.

My amp is bridgable. But I assume if it is bridged then I can't use it for 2 channel (L & R) audio??

Thanks for the informative replies,

Mace

Link to comment
Share on other sites

  • 14 years later...
On 8/11/2002 at 2:35 PM, Malcolm said:

Read the info on the "Hafler circuit" here:

http://www.onhifi.com/askwes/ask0028.htm

 

Last night I tried a simple Hafler circuit (L+ to +, R+ to -) using a DLK 1 speaker I had lying around.  The DLK 1 is considerably less efficient than the Fortes (I'd guess 90dB-92dB/1w) and has considerably less impressive sound.  While I noted an expanded soundstage and a better sense of presence and separation, the sound quality in general took a nosedive with less clarity and more distortion.  I would love to see how a Heresy or Cornwall sounds in this layout: with a good third speaker I think this would make an enormous positive difference in the sound.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...