Bi-Amping and a sub

fliphandywork

He lives!!!
Heres my question concern:

I am seriously considering running a bi-amp setup with two 9090DB's. I already have a Martin Logan Grotto sub that would hook up to the setup via rca cables. If the preamp has two sets of inputs's... left and right, where do I hook up the sub? If I use a y adapter on one of the channels wouldn't that only send that channels frequencys to the sub?

Please help!
 
Not sure what you are wanting to do here. The Grotto sub has LFE (Low Frequency Effects) input, RCA input, and speaker-level input, and of course it's own amplifier. So I'm not sure where the bi-amping comes into play here, or why you need two receivers to accomplish this.

Running a sub with a standard L&R stereo setup usually isn't considered biamping. If you have L&R speakers that allow biampng (and if that's your goal), the high-end of each will require much, much less power than the lower end, and a whole 'nother receiver is way overkill. A decent 40W/ch amp, such as a stand-alone amp or an integrated with pre-out/main-in jacks will be plenty for the upper end with 99% of the speakers out there. If you want to stick with Sansui gear, then maybe Beatlefred will chime in with some info on a small Sansui integrated with preout/main-in jacks (and if the small integrated's don't have 'em, they can be added...) Even here, with biamping, you need some sort of active crossover between the preamp and the amps.
 
What I want to do is as follows:

My B&W DM604 allow for biwiring-biamping. I want to biamp them. The confusing part for me is where the sub would be physically hooked up. If the preamp has two sets of inputs then they would both be used. One by the left amp and one by the right amp. So that brings me back to my question. Where does the sub get plugged into?

Now active crossover? What does a home active crossover look like? Where can I get one?

Is the advantage that great with biamping?

Oh yeah! Chiefs and Colts this Sunday... whos going to win?
 
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If the Chief's defense can get their head out, then KC might pull it off.:D

Let's start with basics... The individual drivers in your speaker cabinet are designed to amplify specific frequencies. The woofer probably can't reproduce frequencies above 3K very well, the midrange probably has a response from 1.5K to 5 or 6K, and the tweeter probably takes over at 6 or 7K.

Although feeding the high frequencies to the woofer won't hurt anything, it's best to filter them out. However, the inverse is not true with the mid and tweeter. A watt or so of 100Hz music to the midrange or tweeter will cause it to expire in a rapid fashon. So the low frequencies must be filtered out.

Now...driving the speakers as they come out of the box from the manufacturer and simply connecting them to a receiver, you are using the filtering network built into the speakers...the crossover. Because it contains no active components (only capacitors, resistors, and inductors), it is referred to as a 'passive' crossover. It's job is to filter the incoming full-range audio signal to the various driver components in the cabinet.

Biamping is another method of filtering. Instead of having passive components filter the signal, active components (opamps, transistors, etc) do the filtering. I believe if the B&W's allow biamping, then the passive filter network stays in place between the mid driver and the tweeter.

Do some reading here.

In your case...with a midrange and a tweeter on the upper end, perhaps a little more power than I had first recommended might be in order. Perhaps a nice AU-517 or a AU-717 would work well.

The subwoofer has its own crossover, and high-level inputs that could be connected to the speaker terminals of the 9090DB, or it also has RCA inputs, which could be connected to the pre-out of the 9090DB with a 'Y' cable. Because the sub might be placed some distance from the rest of the components, I'd use the high-level inputs...connecting them to the power output of the 9090DB. Small 20ga speaker wire would be fine here, as the sub does not pull any real current from the high level inputs.

(BTW, the 9090DB puts all the speaker outputs in series, which means that you can't connect the B&W's to the 'A' speaker connector, and the sub to the 'B' connector...you'd have to find a way to tap the signal, or just use a small 22ga wire and sneak it into the 'A' connector along with the wire running to the B&W's).
 
Good info, EW. I believe though, the question asked was: if a preamp with two outputs (Sansui CA-3000 or CA-2000) is connected to two 9090DB's that are switched into their power amp sections, and one 9090DB drives the left speaker and the other 9090DB drives the right speaker, and w/o the use of any external crossover devices, where in this configuration would a subwoofer be connected to? (though the point may be raised if a subwoofer is actually needed in this arrangement at the risk of it being "overkill")

Some more info:

http://www.audioasylum.com/audio/general/messages/57210.html


B/F
 
How you read that much into his original post I'm still trying to figure out...but of that's what he meant, then I'm wondering what the second 9090 is for. I mean...with two 9090's, there are four amp channels...so what are the other two channels for?? The 9090 is NOT bridgable...so clue me in here.

If you...fliphandywork...were going to use one channel each of a 9090 for the mids and tweets in a biamp setup, those channels would be loafing half the time. Like I said...65-85W would be more than enough for the mids and tweets.

As far as where to get the signal for the sub...same place I pointed out before in my last post.

All in all, I think you're trying to kludge too much stuff together to accomplish a fairly simple task. If you want to use a high-quality preamp, then start hunting for a high-quality amp or two to go with it. A pair of receivers used only for their amp sections is kind of a waste.
 
The reason that I thought I needed to use two 9090DB's in this setup is because everything that I read said to use identical amps. I was looking at vertical bi-amping so I think that is why it said to use identical. From the reading I have done what you are explaining is horizontal bi-amping. I think a au-717 would be a good fit. 85wpc.

The reason I would use a sub is because I already have one. To me there is no reason not to use it. I do occassiocally watch movies on this setup, so it really kicks in on occassions like that.

Does the preamp act as the active crossover?

Thanks for all the input guys.

Echowars... Nice diagram!
 
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There is nothing wrong with the preamp section of a properly functioning 9090DB...unless you just want to collect more gear and find a nice preamp. No, no preamp that I know has an active crossover built in. A dedicated external unit is required, such as this Behringer from Parts Express. The Behringer has a dedicated subwoofer output which would simplify connecting the sub...but might mean a long interconnect cable. Also, the Beheringer has only balanced XLR connectors, which would mean some adapters needed to use with consumer RCA jacks (not a huge deal).

Vertical biamping supposedly places less load on each amp, since only one channel has to handle the bass frequencies. I personally think it's hogwash...a properly designed amp will handle pretty much anything you throw at it. There is nothing wrong with doing it that way, but buying another 9090DB just to get a couple more amp channels is kinda bogus, and the 'theory' of the vertical thing assumes that there is some inherent flaw in your amp that requires the load be lightened by using one channel to amplify the highs. Maybe if you're running the thing at club levels constantly...I dunno.

Even a 517 has the capabilty to accelerate your mid and tweet through the rear listening wall...both the 517 and 717 were suggested because of the high quality and both have pre-out/main-in jacks (and also have very good preamp sections....so there's your preamp if you wanted it), but 65WPC is more than enough for the mids and highs...plus the 517 sells for a lot less than the 717. And I suggest a integrated instead of a stand-alone amp since a single amp of less than 100W at an affordable price will be hard to find.
 
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Thanks for all the info.

So I could use the existing preamp in the 9090DB as the only preamp in this setup? I was under the impression that I would have to have the following equipment:

Amp 1
Amp 2
Preamp
Tuner
Electronic Crossover

I want to have one central volume control.

That is all I know of. I would really appreciate it if you could list what I would actually need. As your far more knowledgable than I am about this stuff.

How do I get around the XLR inputs and outputs?

Thanks
 
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EW:

Flip's question and my explanation goes back to his post regarding the BA-5000/B&W speakers, perhaps you didnt read it:


Basically, you can either vertically biamp of horizontally biamp. As I mentioned before, you can do a search Online to read more info on it, pros & cons etc...

If you were to use two different amps to biamp, its preferable to use the higher wattage amp to drive the woofers of both speakers and the lower wattage amp drives the tweeter/midrange in both speakers. This would be an example of horizontal biamping.

If you were to use two amps that were identical, such as two 9090DB's, then in my opinion, vertical biamping is the preferred configuration. One 9090DB drives the left speaker, the other 9090DB drives the right speaker. The 9090DB is a receiver but its preamp/power amp section are separable, so switch both 9090DB's into power amp mode and then a Sansui preamp with two pairs of outputs would connect to each 9090DB. (otherwise, you'd have to adjust the volume two times- the 9090DB volume on the right spkr and the 9090DB volume on the left spkr, and turn them up equally so the volume coming from each speaker is the same and one isnt louder than the other, comprende'? The preamp with two pairs of Outs takes care of that problem nicely, one single volume control on the preamp controls the overall volume. If you use a preamp with only one pair of outputs, then you'd need to get a splitter cable to send the output signal of the preamp to each 9090DB. Not a big deal to do that, but a preamp with two outs is certainly a very useful feature- and now you have a good justification to treat yourself to buying a nice CA-2000 preamp on Ebay (as well as a 2nd 9090DB) :)

Note the difference between the two types of biamping. With horizontal, one amp has to do the work of driving the woofers in BOTH speakers. But with vertical, each amp just handles the woofer in the one speaker theyre driving

When you connect each amp to the speaker in VB, it can look tricky because your amp has a left & right channel BUT, the amp is only driving the one speaker, so... how to connect the amp's right channel terminals when its driving the left speaker and vice versa for the other amp's left terminals driving the right speaker??

The connection is made as follows:

9090DB Left channel + to Speaker Left woofer terminal. Then 9090DB left channel - to Speaker Left's right woofer terminal. Then 9090DB right channel + to Speaker left's tweeter/midrange terminal. Then 9090DB right channel - to Speaker left's right tweeter/midrange terminal.

You then repeat this connection for the other 9090DB thats connected to the right speaker.

I imagine if you do a search Online, there will be diagrams of the connections which make it alot easier to visualize instead of writing it all out which I have nonetheles graciously done for you.

B/F
 
I read it thanks! I still didn't quite get it. But thanks for the info... appreciate it. I've read the pros and cons and so on and so forth... I wanted to input from someone here(it is a forum) that may have had first hand experience with bi-amping.
 
RE: the 4 amp channels - the first 9090DB's two channels go to 1.) the speaker's woofer section and 2.) the speaker's tweeter/midrange section. Ditto for the 9090DB #2 and the other speaker. This is based on a configuration that doesnt utilize any external crossover network which isnt mandatory in a very high quality speaker (and at the risk of sounding 'unhumble', an example of which is my Infinity Renaissance 90's - another knowledgeable Infinity owner had posted a while back in the Archived Messages here why an ext-Xover is not needed in the Ren 90's. With flip's speakers, maybe a different story, I dunno.. :)


As for whether Biamping will actually produce any significant improvements in sound quality, ---> :dunno: many say yes, many say no, many dont know. So, its up to every individual to decide for themselves and see if it makes any noticeable difference in their hi fi system. Perhaps its reasonable to say that Biamping would be more likely to provide a greater benefit in proportion to a listener's speakers and how inefficient they might be.

B/F
 
Of course you can use the 9090DB as a separate preamp and amp...and in the drawing I posted it is being used as such.

All you need is a crossover, two amp channels for the mids/tweeters, and some adapters.

The two inputs of the crossover have female connectors, so two of these would be needed for the input. The outputs of the crossover are male, so five of these are needed (two for each channel, and one for subwoofer out). The adapters I showed adapt to 1/4" female, so for each adapter, you would need one of these also.

All the adapters are of course because the crossover is intended for Pro gear, not home use. Doesn't mean it won't work fine, buy yeah, you'll have almost as much tied up in adapters as in the crossover itself.

Also, that Beheringer is about the cheapest on the market. Not to say that there is anything terribly wrong with it, but there are models out there that cost more than 10x as much...here is mine.


Edit: BF...I think what we need to know is the internal configuration of the B&W's. If they can be biamped, then I would assume that the only passive network left is for the mid/tweeter. If so, running the speaks without a active crossover will smoke those nice speakers in a hurry.
 
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Copy of message about Xovers I found in my 'ol email folder:



Fred,
I would try to avoid an external X-O because these only seem to worsen the sound of true high-end speakers. The internal passive networks in the renaissance are very well thought out filters: 24 dB / oct for the mid/tweeter, 18 dB/oct for the midrange/midbass coupler, and I believe 12 dB/oct for the midbass/woofer. These slopes and the relative phase shifts below the crossover frequencies appear to be carefully chosen by their engineers. I know from seeing the actual circuits that these are very high grade and not the cheap run of the mill filters used in typical speakers. Refer to the Manley article re: vertical bi-amping and in particular what is said about bypassing internal crossovers and using crossovers before the amps. There are a few speakers (i.e. Linn) which were designed for doing
this, however, their makers have set the crossover frequencies, their
depression at the crossover frequencies, and any phase adjustments. I believe one of the reasons that the renaissance image so well is their associated crossovers. I hope my opinion is of some help and please remember this is just my opinion.

Take care,

Bill
 
Originally posted by fliphandywork
I've read the pros and cons and so on and so forth... I wanted to input from someone here(it is a forum) that may have had first hand experience with bi-amping.
Did you read this: http://sound.westhost.com/bi-amp.htm

IMHO, there is no comparison between a passive network and an active one. And again BF, you bring up one email from one guy discussing biamping one particular speaker. I'm not going to argue the merits of biamping that particular speaker, since that is not the speaker in question. What he says may well hold true for that speaker, but it is not the norm.
 
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EW- Easy there, dawg. I wasnt the one who brought up anything. Nor was I under the impression there even was a debate going on. I simply replied to his question and mentioned some options to him regarding what he could do as far as using two Sansui's amps (receivers) connected with a preamp (Sansui or otherwise) having two pairs of output terminals. I also pointed out the multitude of available resources Online where he could find more information and come to his own conclusions.

If you reread the beginning part of the BA-5000/B&W post, I DID question why he felt the need to biamp and I also mentioned your name in a complimentary way pertaining to the 9090DB you are currently working on for him.

Sincerely,

B/F
 
Yes indeed B/F can appreciate a forum where B/F can decide to either be 'Good B/F' ----> :beerchug: or.......

'BAD B/F!'----> :whip:
 
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