Jump to content
The Klipsch Audio Community
rplace

Basic Speaker Design Question

Recommended Posts

To start out with I know next to nothing about volts, ohms, resistance, parallel, series, etc. so give the the layman's explanation please. 

 

I'm playing around with my first crack at dual woofers. They are 15 inches each and say 8ohms 300 watts max on the back. The little bit I do know centers around how to wire them up....series vs parallel. Note at this point I'm only concerned with the woofers and they have their own amp(s). 2-way system, separate amps for HF and LF. 

 

Back in my tube amp days when the speaker itself did not change but the amp had 4/8/16 ohm taps and somebody asked which should I use the answer always seemed to be try it and see which you like best. In my current situation the solid state amp has only one way to hook up the speakers, but I can change the speakers from parallel to series. I have in fact tried both and seemed to like parallel better, but in not too long things started to sound a bit distorted, so I quickly switched back to series.

 

I'm slightly confused in the picture below that the amplifier shows 8 Ohms in both. From memory I thought by changing the speaker's from say 8 to 4, the amp was able to "give" more power but it had to work "harder" to do it. So you typically needed a more powerful amp for lower Ohm speakers. I also though it was that amp that was seeing either 4 or 8 Ohms due to the wiring of the speakers. Is the picture wrong or my understanding of what is going on?

 

Since I liked the parallel wiring better, my though was to by a second identical amp and run them each in bridged mode and wiring in parallel. What, if anything, is wrong with that line of thinking?

 

Amp's info:

power output:

  • 215 watts x 2 at 8 ohms
  • 350 watts x 2 at 4 ohms
  • 550 watts x 2 at 2 ohms
  • 700 watts x 1 at 8 ohms in bridged mode
  • 1100 watts x 1 at 4 ohms in bridged mode

 

 

 

series_parallel_speakers.jpg.524e2f6b326d87ffd57a02a4c616f8a4.jpg

Share this post


Link to post
Share on other sites
13 minutes ago, rplace said:

To start 

Since I liked the parallel wiring better, my though was to by a second identical amp and run them each in bridged mode and wiring in parallel. What, if anything, is wrong with that line of thinking?

 

If you're talking about using two amps to connect to both woofers at the same time, that's when kaboom happens. 

Share this post


Link to post
Share on other sites
13 minutes ago, wuzzzer said:

 

If you're talking about using two amps to connect to both woofers at the same time, that's when kaboom happens. 

 

Not very helpful. I'm looking for some understanding. Some context. The why.

 

To be clear we are in 2021 so I think we all get the stereo part. That means two physical wooden boxes with "things" that make noise inside. One on the right and one one the left. I'm talking about one physical speaker. So lets just call it the right speaker. Forget the HF for the time being it is all sorted out with its own amp. Now we are down to one speaker (the right) and only the LF. That leaves two 15" woofers for that single right speaker. Make sense?

 

One amp, to one speaker's LF only. That LF happens to be dual 15" woofers. 

Share this post


Link to post
Share on other sites
42 minutes ago, rplace said:

Since I liked the parallel wiring better, my though was to by a second identical amp and run them each in bridged mode and wiring in parallel. What, if anything, is wrong with that line of thinking?

 

I know less than you do so take this with appropriate tonnage of salt....

 

If I understand you, you have two woofer/drivers.  Instead of a single amp powering them both at same time, you are thinking about buying another amp and bridging it so each driver has 700 watts available to it?

 

What instead of buying another amp, you simply take the "right channel" of your amp to driver "1" and your "left" channel of the same amp to your driver "2" and run the amp (if available) in mono so each driver gets same signal??

 

Might be easier to try and see if you like it, save some costs, space, wiring blah blah blah.

 

Now, you can perhaps replace that single amp with "Joe Monster" amp that has appropriate power rather than bridging it.

 

Though I'm pretty sure the above would work, I realize it still might not be what you want to do.

 

I kicked myself after I buried my Danley behind the fireplace.  It has two drivers and I'm using a single amp.  That said I'm only using one channel of the K2.  After I got it all buttoned down, it dawned on me that I could have run a second wire and used both channels as I described above.  I could still bridge it but frankly, there's no need.....the single channel will rattle enough of the windows.

 

(my comments might be an example of keeping your mouth closed so you don't prove your ignorance to everyone!)

 

  • Thanks 1

Share this post


Link to post
Share on other sites

You could do that or just pick up a more powerful amp that is 4 ohm stable that can handle the load of 4 large drivers.

 

I had a pair of Carver a400x's running bridged mode on a pair of Klipsch pro subs and they sounded ok, swapped them both out for a single Samson pro amp at 1100x2 @ 4 ohms and they sounded significantly better.

  • Thanks 2

Share this post


Link to post
Share on other sites

I think in the case of dual driver bass bins if you're going to run a pair of amps (one for each bin) it would probably be better to use both channels in stereo one for each woofer; less strain on the amp and double the damping factor. 

  • Thanks 1

Share this post


Link to post
Share on other sites
35 minutes ago, rplace said:

 

Not very helpful. I'm looking for some understanding. Some context. The why.

 

Sorry, the way you phrased the question seemed like you were going to use two amps bridged to connect to two woofers and then connect the woofers to each other at the same time. 

Share this post


Link to post
Share on other sites
9 minutes ago, jjptkd said:

I think in the case of dual driver bass bins if you're going to run a pair of amps (one for each bin) it would probably be better to use both channels in stereo one for each woofer; less strain on the amp and double the damping factor. 

 

Interesting. I had not thought of that. How does it work? From the single speakers standpoint do I just run Amp 1 Channel 1 to one, single, woofer then Amp1 Channel 2 to the OTHER single woofer in the same physical speaker box?

 

for the full picture I have all balanced connections from preamp to Xilica 8080 to amp(s). Having trouble seeing in my minds eye how I get say the right LF signal into Amp 1's channel 1 and channel 2 without splitting that single Right out into two via a wye cable or the like. I'm not sure I have enough line out's on the Xilica to map the right LF signal to two distinct outputs. Am I making sense?

Share this post


Link to post
Share on other sites
1 hour ago, rplace said:

Back in my tube amp days when the speaker itself did not change but the amp had 4/8/16 ohm taps and somebody asked which should I use the answer always seemed to be try it and see which you like best. 

This is a separate issue having to do with tube-type amplifiers (and certain SS amps --like those made by McIntosh with output transformers)--and not related to the load itself: the impedance of the drivers in series or parallel. 

 

Tubes have an issue with matching output impedance with the load input impedance in order to provide maximum power transfer to the load (acoustic drivers)--because they have very limited output power capabilities (as compared to power transistors) and the fact that their output impedances are very high as compared to typical transistor amplifiers. 

 

1 hour ago, rplace said:

I'm slightly confused in the picture below that the amplifier shows 8 Ohms in both. From memory I thought by changing the speaker's from say 8 to 4, the amp was able to "give" more power but it had to work "harder" to do it. So you typically needed a more powerful amp for lower Ohm speakers. I also though it was that amp that was seeing either 4 or 8 Ohms due to the wiring of the speakers. Is the picture wrong or my understanding of what is going on?

This is essentially correct: tube and transistor amplifiers are both much more limited in terms of the voltage output they can provide vs. the current output they can provide.  (It's the product of current x voltage that determines the quantity we call "power".)

 

Reducing the load impedance via parallel wiring of drivers and use of lower impedance drivers themselves (4 ohms vs. 8 ohms or even 16 ohms) allows the amplifiers to shine with their greatly increased current output capabilities at lower voltages--right up to the point that they go unstable (like the load is shorted across the amplifier terminals).  So you have to be very careful with very low input impedance drivers-.  Generally, it's advised that you stay above 4 ohms impedance. 

 

Most tube amplifiers REALLY don't like to run without a load (infinite impedance) or zero impedance (a shorted output).  They need controlled load characteristics. 

 

1 hour ago, rplace said:

Since I liked the parallel wiring better, my though was to by a second identical amp and run them each in bridged mode and wiring in parallel. What, if anything, is wrong with that line of thinking?

No, you probably need to bi-amp the amplifiers to the woofers in order to keep them from seeing a de-stabilizing load (overrunning, that is, since woofers have moving mass).  It's the "reactance" of the load that destroys the amplifiers, once the total load impedance is above a certain value. 

 

So you should probably just wire each woofer to a separate amplifier rather than strapping their outputs and running in parallel.  You'll get better performance, and greater amplifier safety margins.

 

Chris

  • Like 1

Share this post


Link to post
Share on other sites
41 minutes ago, Chris A said:

No, you probably need to bi-amp the amplifiers to the woofers in order to keep them from seeing an de-stabilizing load (overrunning, that is, since woofers have moving mass).  It's the "reactance" of the load that destroys the amplifiers, once the total load impedance is above a certain value. 

 

So you should probably just wire each woofer to a separate amplifier rather than strapping their outputs and running in parallel.  You'll get better performance, and greater amplifier safety margins.

 

Thanks Chris, as usual. Is that the same thing @jjptkd was saying in a different way? That is 2 speakers, two woofers each. Two amps 2 channels each so:

Amp1/Channel1 to Speaker1 Woofer 1

Amp1/Channel2 to Speaker 1 Woofer 2

Amp2/Channel1 to Speaker 2 Woofer 1

Amp2/Channel2 to Speaker 2 Woofer 2

 

That all makes sense if it is better for the amp to not be running in Bridged mode for some reason (resistance, current, what have you) I don't fully understand. But I can't see how to easily get, say, the right LF single output to Amp1 Channel 1 and Channel 2 in my pea-brain.

 

Not to add too many wrinkles...but in the interest of full disclosure I saw a good deal and already bought the 2nd identical amp. So originally I had one, single amp (Crown XLS 1002 specs above in first post). Running Channel 1 to right speaker (dual 15" woofers) wired in series and Channel 2 to left speaker (dual 15" woofers) wired in series. Now I have two Crown XLS 1002 amps.

 

So buying a "bigger single amp" is not really in the cards. The hand I am dealt is 2 identical amps with the specs above and wondering what my best options is.

 

Maybe my expectations were a bit to high. I hastily bridged the two amps and rewired from Series to Parallel and honestly don't notice any difference. From memory, months back, when I had the single amp and experimented with series vs parallel I noticed  what I thought was quite a bit more authority in the low end.

 

Thoughts? 

Share this post


Link to post
Share on other sites

I went through something like this with the Jubilee bass bins. The McIntosh amps, 200w per channel x2 at 8 ohms,  I have are not capable of bridging with the two woofers in the bass bin so I asked Roy about running each woofer with a separate channel of the same amp. Not speaking for Roy on your question, he told me I had other issues and he did not recommend the 2 channel approach. Essentially 200w was plenty for the bass bin at home. I experimented with speaker position which did make it better. Chris A did help me with the DSP part. I was having lack of bass issues and was trying to use what I had to fix it - 2 of those Mac amps so trying to figure out how to bridge or use 2 channels on each bass bin. End result was speaker position and then adding a 1502.

 

is there a problem you are trying to fix?

  • Like 1

Share this post


Link to post
Share on other sites

Direct radiating woofers require considerably more power than if those same woofers are fully horn loaded.  The power needed by the dual 12" woofers in the Jubilee bass bins is much, much lower than if you were going to use them in direct radiating mode (about 15 dB watts more power for the same output SPL on-axis).  The Jubilee bass bin doesn't need that power, and in fact, providing amplifiers having too great an output power capability brings its own problems (noise, potential for destroying or significantly damaging the voice coils or annealing neodymium  magnet permanent fields, etc.).

 

The issue with bi-amping the woofers in parallel is that it implies that the amplifiers must be twins--just like the woofers--in order to keep the stereo imaging from wandering around due to differences between the amplifier transfer functions (SPL and phase response) and driver transfer functions.  If you strap the amplifiers together, you eliminate some of that tendency for the stereo image to wander, but you bring other issues--notably the amplifiers would need to be designed to be strapped (bridged mono operation).

 

Chris

Share this post


Link to post
Share on other sites
28 minutes ago, Ole Dollar said:

is there a problem you are trying to fix?

 

Not really. I think I suffer a bit from always thinking there is something better around the corner. Or what if this, maybe that, perhaps this and that.

 

Maybe it was just expectation bias but I did think I heard an improvement with the single amp and switching from series to parallel wiring. I also believe after 20 minutes or so I detected some distortion. That made me think that while the reduced load from 8 to 4 ohms let the amp shine a bit more it also made it work harder than it should driving 4 X 15" woofers. These are open baffle mind you so not efficient horn loaded bass. See picture below.

 

So I jumped to the conclusion that more is better and that two amps bridged over one amp driving two channels was a simple and relatively cheap thing to try. My thinking was that 215w@8 Ohms vs 1100@4 Ohms Bridged would be a fairly straight forward solution. 

 

rps20210219_140035.thumb.jpg.655b0a97e3daf6da74347ec05e007b51.jpg

  • Like 1

Share this post


Link to post
Share on other sites
1 minute ago, Chris A said:

The issue with bi-amping the woofers in parallel is that it implies that the amplifiers must be twins--just like the woofers--in order to keep the stereo imaging from wandering around due to differences between the amplifier transfer functions (SPL and phase response) and driver transfer functions.  If you strap the amplifiers together, you eliminate some of that tendency for the stereo image to wander, but you bring other issues--notably the amplifiers would need to be designed to be strapped (bridged mono operation).

 

The Crown XLS in question have clear marketing for bridging, provide an LCD menu system to set them up that way and mark the back speaker terminals for bridging. They seem to almost beg you to try it. I'm happy to go back to what I had and return the 2nd amp. Or try something besides bridging the two.

 

With 4 channels of identical amp power and 4 woofers it seems like 1 woofer per channel is the next logical test. I'm just unclear on how to make the single right output and single left output feed 2-channels in each amp. Is this worth perusing or should I just go back to 1 amp, 1 channel per dual woofers at 8 ohms? If for no other reason than to experiment I'd like to try one amp channel per woofer if that is reasonable.

Share this post


Link to post
Share on other sites
Just now, rplace said:

The Crown XLS in question have clear marketing for bridging, provide an LCD menu system to set them up that way and mark the back speaker terminals for bridging. They seem to almost beg you to try it.

Try it, then.  Just don't overdrive the woofers with too much power.  You can set a limiters in DSP-front-end amplifiers (like the XLS series) so you can prevent a lot of the issues of destroying the drivers.  The background noise levels might be a bit higher, though.

 

Chris

Share this post


Link to post
Share on other sites

While I do subscribe to the “Tim the tool man” approach - more power - I am courteous as to when you will drive the speakers with 2200 watts. I have done PA work for many years and have used 2000 watts to fill a large area which did not translate well to the home environment. 
 

On a side note I tried a Crown 1500, first version of amp, on the bass bins and was disappointed in the sound stage at home, very flat, same with main speakers in PA use. The 1500 does work well as a subwoofer amp and is powering the 1502 sub I have. 
 

Since you have the XLS 1002, third version of that amp, are you happy with the sound quality? 

Share this post


Link to post
Share on other sites

My $0.02, I know I am late to this. But to make sure it gets stated, the 8 ohms labeled on the amps in your first post is a red herring. Modern day SS amps have an output impedance of closer to 0 ohms than anywhere near 8 ohms. If you're going to buy/try 2 amps the way to get the most possible power is to run the speakers in parallel and bridge the amps output.

  • Like 1

Share this post


Link to post
Share on other sites
31 minutes ago, Chris A said:

Try it, then

 

I have. I'm probably not being clear. I started out asking the basic question in a hypothetical way. I should have started form the beginning saying I already have done the following.

  • 1 amp driving 2 speakers with dual 15" 8 Ohm drivers each wired in series
  • 1 amp driving 2 speakers with dual 15" 8ohm  drivers each wired in parallel (seemed "better" but questioned distortion after 20 minutes or so)
  • 2 amps each bridged, driving 1 speaker each wired in parallel (seemed like no difference from the 1 amp series experiment)

 

Prior to today I though my only option was to bridge. Similar to having mon-block amps, of which I have had several sets...but always tube based. In my mind it was one physical box (bridged) per speaker the only variable at that point was parallel or series.

 

It never dawned on me that I could have two stereo amps and use one amp channel per actual driver (to be painfully clear not bridging them but using each channel for each woofer). But if I do that I need, or I think I need, 4 balanced XLR wires (2 right and 2 left) one for each amp channel which in turn goes to each woofer (2 right and 2 left). How to do this? In the RCA wire days I'd have use a Wye cable, but my gut say don't do that with balanced connections.

 

All help appreciated. I'm probably making more complicated that necessary. Just tell me what to try next with 4 amp channels and 4 woofers. I'm on board with giving up on bridging the two amps.

Share this post


Link to post
Share on other sites
5 minutes ago, Ole Dollar said:

I am courteous as to when you will drive the speakers with 2200 watts

Never. I read somewhere that having amp power 2 times the max of the driver was a good general rule. The individual 15" 8 ohm driver are rated at 300W max. So since I already had one 1002 XLS and it was what it was. Buying a 2nd and bridging made sense at the time given my limited knowledge, sale price and knee jerk reaction to more is better....like Tim you mentioned. I was just trying to get above the 215w mark that it was in plain vanilla mode. I really didn't need anything more. Figured I could sell the extra amp if no difference but be better off in my mind for having at least tried.

 

6 minutes ago, Ole Dollar said:

Since you have the XLS 1002, third version of that amp, are you happy with the sound quality? 

 

I'm only using the Crown's for the LF. I've got Nelson Pass First Watt J2 for the HF. I'm VERY VERY happy with the FW J2 driving the HF sections of both speakers. I'm more than happy with the single Crown on the 4X 15"ers. I have a much more amazing sound stage than I ever did with Khorns. Mostly due to Chris's help, the 2-way active set up and getting phase/delay/etc. dialed in.

 

I'm really talking about that last 5% or less. I'm really just finding a reason to mess with things and try to learn a little in the process.

 

Appreciate the help from all.

 

14 minutes ago, babadono said:

If you're going to buy/try 2 amps the way to get the most possible power is to run the speakers in parallel and bridge the amps output.

 

That is what I thought given my limited knowledge. Two stereo amps acting like a "bigger" mono block pair. I though this was a way to go from an 8 ohm load to a 4 ohm load and not hurt the drivers or amp. I expected to need to turn the amp's gain control knobs down if I kept the same settings in Xilica. I did not. I actually did not notice any different "loudness" to my ears going form 8 ohm wiring single amp to 4 ohm wiring dual bridged amps. That seemed odd to me. However I've not actually measured the output yet.

  • Like 1

Share this post


Link to post
Share on other sites
20 minutes ago, rplace said:

I'm probably making more complicated that necessary.

 

Just get some MWM Grand's and call it a day... :ph34r2:

Share this post


Link to post
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...