PDA

View Full Version : [Help Needed] Dual-Amping



bakerbob
09-05-2011, 12:39 AM
I'm a neophyte and I know I'm a neophyte. I've been blessed with enough time and money to buy some equipment and experiment a little. My good stereo and the home theater has all Polk speakers... That's how I got acquainted with this forum.

Right now 2 Boston Acoustics CS-226 are connected to an Onkyo M-501 power amp that is connected to an Onkyo TX-8555 receiver's pre-out RCA sockets.

I just ordered another M-501... I want to connect a Y cable to each of the RCA sockets on the receiver. Then send just the left signal to one of the power amps and send just the right signal to the other amp. Then connect just one speaker to each of the amps.

The speakers are rated for 250 WPC the amps are 150 WPC I saw this configuration on-line (see attachment) and was hoping it would boost the power going to the speakers without doing any damage to anything, this may just be a "project" stereo but I don't want to damage equipment or cause a fire.
http://www.wired4sound.net.au/public_html/bi_wiring.pdf

Thank you
Gary

dcmartinpc
09-05-2011, 12:50 AM
First off, Welcome to Club Polk! Glad to have you here! There is nothing wrong with being a beginner. We were all beginners at some point.

I am not sure how this really gains you anything since you cannot bridge the M-501 that I am aware of... Someone please correct me if I am wrong. Since the CS-226 are not biampable, an active crossover before the amps isnt even an option.

Did I misunderstand what you are trying to do? You can't just connect both sets of speakers wire to the same binding posts. It is very important that you do not do this. You could damage the amplifier.

Again welcome. Plenty of helpful people here! If I shot way over your head, I am sorry. Please let me know if I did and I can try to explain a little further.

Don

bakerbob
09-05-2011, 01:09 AM
Thank you for getting back. The schematic I attached is about what I want to do... except where it says preamp that's where the receiver would be.
In the article (wired4sound link) it said that this configuration would yield more power to the speakers since one amp and one speaker would be devoted to the left and one speaker and one amp would be devoted to the right.
To me it sounds logical that 1 amp on each side would produce more power than a single amp's power being split for left and right.
But I don't know anything... yet :)

dcmartinpc
09-05-2011, 01:23 AM
Sorry I missed that diagram the first time!


Do your speakers have two sets of speaker terminals? When I looked them up, I only saw one... That configuration does definitely supply more power to the speakers, but to do it right, you need to add an active crossover in between the pre amp and the amplifiers. Again, I don't think those speakers are bi-ampable based on what I am finding.

Don

bakerbob
09-05-2011, 02:13 AM
OK... Please be patient.

The article I read made several distinctions dual amping is different than bi-wiring and different from bi-amping and he mentioned several other configurations... all of which I only have the vaguest understanding.

I attached a picture of what I think, you think that I am trying to do. I can see where this would work (bi-amping)... But it also looks like what I want to try (dual-amping) would work also.

Why would my speakers need 2 sets of binding posts and why would I need the crossover. I may possibly too ignorant to have this conversation. What would an "Active Crossover" look like... I have the pre-amp (Onkyo P-301) that was built for these amps... would it have an Active Crossover function?

20hz
09-05-2011, 05:12 AM
OK... Please be patient.

The article I read made several distinctions dual amping is different than bi-wiring and different from bi-amping and he mentioned several other configurations... all of which I only have the vaguest understanding.

I attached a picture of what I think, you think that I am trying to do. I can see where this would work (bi-amping)... But it also looks like what I want to try (dual-amping) would work also.

Why would my speakers need 2 sets of binding posts and why would I need the crossover. I may possibly too ignorant to have this conversation. What would an "Active Crossover" look like... I have the pre-amp (Onkyo P-301) that was built for these amps... would it have an Active Crossover function?

I use a active elecronic crossover a Energy EAC with that I run one amp to my smaller speakers (polk monitor 5's) and a bigger amp to drive my subs .On the Energy EAC it has volume for each amp and a selectable crossover point for them to operate on , for example I can adjust it so the subs work at 70 hertz and down and the smaller polks only operate at 70 hetz and up , this way the signal going that way wont get bass to destroy my polks plus ALL levels and frequencys are adjustable .

chindman
09-05-2011, 07:58 AM
OK... Please be patient.

Why would my speakers need 2 sets of binding posts and why would I need the crossover. I may possibly too ignorant to have this conversation. What would an "Active Crossover" look like... I have the pre-amp (Onkyo P-301) that was built for these amps... would it have an Active Crossover function?

The diagram you posted answers your own question. It shows separate signal paths to the low and high frequecy drivers of each speaker. If your speakers do not have these separated inputs then you cannot do anything be it bi-amping, dual amping or anything else(IMHO bi-wiring should be reserved for people that are bi-polar because it will accomplis nothing sonically significant).The telltale sign that separable paths exist is that you have 4 binding posts (not 2!) on the speaker.

If you have the separable inputs then you are good to go with one of these schemes depending upon whether the separate inputs can also bypass the internal driver specific crossover components(good for dual-amping w low level crossover filtering) or not (bi-amping using the speaker driver networks separately) . W/o the separable inputs then you will have to create them by doing surgery on the speakers or look for another project. Most dual input speakers allow separation of the high pass and lopass networks but do not bypass them i.e they are bi-ampable. Improved power output derives from the higher impedances seen by the amplifier at frequencies that are not being used by the particular driver it serves.

Unless your amplifier is underpowered for your speakers, room dimensions and acoustics, the main advantage of biamping, dual amping etc. is not to get more power to the speakers, it is to get better response by isolating each driver from the electrical loading consequences of the other driver being driven in the same circuit. Depending upon the speaker consruction and crossover network this can reduce distortion and improve transient response, but generally performs best in the first sketch of the article you referenced with the low level cross over so each power amp only "sees" the frequencies appropriate to the driver it services and thus delivers more usable output. This provides real power gain, but is not trivial to implement well because you need to know the crossover characteristics of the speakers you are driving and should be able bypass the internal networks of the speaker to get best advantage. If you cannot bypass then the lopass cuttoff needs to be well above the speakers internal crossover frequency and the highpass cuttoff well below it abd that is not a crossover filter.

dcmartinpc
09-05-2011, 10:06 AM
The diagram you posted answers your own question. It shows separate signal paths to the low and high frequecy drivers of each speaker. If your speakers do not have these separated inputs then you cannot do anything be it bi-amping, dual amping or anything else(IMHO bi-wiring should be reserved for people that are bi-polar because it will accomplis nothing sonically significant).The telltale sign that separable paths exist is that you have 4 binding posts (not 2!) on the speaker.

If you have the separable inputs then you are good to go with one of these schemes depending upon whether the separate inputs can also bypass the internal driver specific crossover components(good for dual-amping w low level crossover filtering) or not (bi-amping using the speaker driver networks separately) . W/o the separable inputs then you will have to create them by doing surgery on the speakers or look for another project. Most dual input speakers allow separation of the high pass and lopass networks but do not bypass them i.e they are bi-ampable. Improved power output derives from the higher impedances seen by the amplifier at frequencies that are not being used by the particular driver it serves.

Unless your amplifier is underpowered for your speakers, room dimensions and acoustics, the main advantage of biamping, dual amping etc. is not to get more power to the speakers, it is to get better response by isolating each driver from the electrical loading consequences of the other driver being driven in the same circuit. Depending upon the speaker consruction and crossover network this can reduce distortion and improve transient response, but generally performs best in the first sketch of the article you referenced with the low level cross over so each power amp only "sees" the frequencies appropriate to the driver it services and thus delivers more usable output. This provides real power gain, but is not trivial to implement well because you need to know the crossover characteristics of the speakers you are driving and should be able bypass the internal networks of the speaker to get best advantage. If you cannot bypass then the lopass cuttoff needs to be well above the speakers internal crossover frequency and the highpass cuttoff well below it abd that is not a crossover filter.

First off, Welcome to Club Polk, and Excellent first post!!! Jumping right in! I was too tired last night to give the explanation, but you did an excellent job.

This is what I was trying to communicate last night :biggrin:

Don

bakerbob
09-05-2011, 05:49 PM
Thank you very much for the reply, I can see that you weren't just blowing me off, you took some time to read what I wrote at try to respond, and your response will probably be very helpful to other members of the forum.

But I didn't understand much of it.
Nobody has warned me that I would damage equipment or start a fire (my original concerns) so I guess I'll do a trial and error thing later this week.

I am understanding that drawing a little better... I see now that it does call for 4 terminals... Maybe I'll end up buying some second hand Monitor 70's from eBay, or whatever Bostons equivalent is.
The prints I read at work are different... My bad.
I think I'll wire up the amps to the receiver.
I suspect that when I touch the speaker wires to the terminals that are physically on the left of one the amps I will get a strong signal (a weak signal from the other). Then I will connect the other speaker to the terminals that are physically on the other side of the other amp. It is my thought that is configuration will be safe and yield more power to the speakers.

People have mentioned "Crossovers" and I have done a little research and think I have a basic understanding... They kinda' look like a subwoofer... dials and switches among them are volume control and Hz control. I see that they sell them at both Amazon and Parts Express... When I get some more money a crossover will probably be the next thing I experiment with.

Once again thanks for all the help!
Gary

The good news is that I have been using the first amp (at low volume) all weekend and it seems to be safe and working well :)

reeltrouble1
09-05-2011, 07:21 PM
hello baker....hehehehe..welcome to the land of C is for Cookie!!! C is for Cookie!!! Sometimes the passion boils over and the terms get thrown around without understanding your at the start of things.....

do your speakers have a total of four connecting posts on each one...say a set mounted directly above another set? If so yes you can bi-amp them. If there are any wires or metal pieces connecting the two sets of posts take those off or you can damage your speakers and gear.

have fun.

RT1

RT1

tonyb
09-05-2011, 10:31 PM
I've got to mark this day, write it down,store it in the safe.

Ted made a post.....I can understand !! WOOHOO......:tongue::biggrin:

reeltrouble1
09-05-2011, 11:29 PM
yea, well, I sure don't want anyone to get used to it......you can go wire to wire yet at the end it all comes down to the wire.

RT1

20hz
09-10-2011, 03:07 PM
Thank you very much for the reply, I can see that you weren't just blowing me off, you took some time to read what I wrote at try to respond, and your response will probably be very helpful to other members of the forum.

But I didn't understand much of it.
Nobody has warned me that I would damage equipment or start a fire (my original concerns) so I guess I'll do a trial and error thing later this week.
People have mentioned "Crossovers" and I have done a little research and think I have a basic understanding... They kinda' look like a subwoofer... dials and switches among them are volume control and Hz control. I see that they sell them at both Amazon and Parts Express... When I get some more money a crossover will probably be the next thing I experiment with.

Once again thanks for all the help!
Gary

The good news is that I have been using the first amp (at low volume) all weekend and it seems to be safe and working well :)

Before I got my energy crossover I used a mtx car crossover (at home) with a "wall wort" power suppley it works fine and its a fun experament just be sure you are confidant and understand the wiring .
What kind of amp did you choose for your first amp ?
IF YOU ARE NOT DONT TRY IT .

F1nut
09-11-2011, 10:51 PM
Rather than adding a second amp, I suggest you replace that receiver with a real pre amp, preferably tubed. You will thank me later.