I'll give my two cents on this issue since it is my major gripe with this otherwise very good preamp.

1. The whole idea of dvd-a/sacd bass management (redirecting bass) works well if you have satellites and a single sub. If you have full range speakers (which I do on all except center) BM is not needed! Nor should it be wanted.

2. I recently added another sub for "stereo subs". The best thing I ever did for my system. The subs are fed L/R line levels and also the LFE mono. In all situations (except 6ch input) all speakers play full range and the subs just augment the lowest bass for the fronts. With the current 950 BM setup you get the double bass with BM set to off and you get mono bass with BM set to on.

The mono bass is what I don't like. I don't think anyone would like it if their stereo only setup forced mono only bass from their speakers regardless of their speakers capabilities.


I don't agree. Every DVD-A I have puts very limited bass to the center and surrounds. As I said my center won't play deep bass but they don't seem to be trying to. I don't think the producers are channeling that much bass to the centers or surrounds and even if they did the speakers just won't reproduce it.


I again disagree. I have three subs and it was much easier to balance the bass response in the room because multiple subs help fill in each others peaks and valleys.

It just bothers me that the inputs used for DVD-A/SACD force you into a certain configuration. These two formats are currently my highest quality sources and the 950 is putting me into a box with the forced mono bass summing.

I would like SH to please describe how he handles this BM issue (or lack of) with his stereo subs if he even uses the 6ch inputs.

Keta- I hear ya , but I would have some questions. You say you have full range speakers. -3 dB point is 20 Hz? *And*, you have tested that with a calibrated microphone and a software package something like ETF so that you know that you are only getting direct, and not reflected (bass augmented) sound? I know that a lot of manufacturers put forth the claim that they have "useable" output down to 20 Hz, but that is something like - 10 dB, not - 3dB. -3 dB at 20 Hz speakers do exist, but they are rare and do cost some denaro.

Even if you do have full range speakers, crossing them over *will* help them sound even better because driving low freqs is not easy. (I bet BoB and SH can phrase this better than I can. Better dynamic range in the the midrange.)



Ahhh, but you are balancing the valleys of 1 channel with the peaks from another? That's not right. The goal should be flat response with *each* sub, and not with all three going. Otherwise for example, you're filling in the valleys from say the left channel speaker with bass from the right channel. That's different content!

The best rule of thumb I ever came across for multiple subs? Stack them all in the same place. Whether it's a corner, or along a wall.

Then there's the question of sure, they can reproduce 90 db at 20Hz (1 watt or so) but what happens when a reference level or higher (say 100 watt) signal gets sent out - can they really reproduce a 110 db note at 20Hz? Pretty unlikely.

As for stacking subs, lots of folks like it, but I don't. My personal best results have been (1) corners of a symetrical room and (2) a horizontal line array. Maybe this is what Kevin means by 'along a wall'?

YMMV.

Charlie

DITTO! I don't own a 950 and it offers alot to make me want one, but this just may a deal breaker for me. 5.1 direct should be just that, DIRECT, no summed bass, no nutin'.
Has anyone investigated what it would take to modify a 950 to defeat the summed bass? I'd hate to break an otherwise great warranty to fix a design flaw (IMHO), but if it is possible to modify then I might consider a purchase. Now there is the missing LFE on DTS-ES. I really wanna like this pre-pro but it's getting more difficult the more I read about some of these quirks. Hey, no product is perfect but these seem to be pretty basic issues (at least they are with me).


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Tekdredger

[This message has been edited by Keta (edited March 06, 2003).]

[This message has been edited by Keta (edited March 06, 2003).]

what anyone 'thinks' producers are doing with sacd/dvd-a doesn't negate the fact that they are formats that are capable of 6 full range channels. i own several sacd discs that contain full range surround tracks and several others that have unfiltered kick drum in the center channel (and my sacd library doesn't put a dent in the list of available software). at low enough volumes, this won't hurt the speakers, but the information on those tracks isn't being reproduced when BM is switched 'off', if there were no double bass, that is. at ref level, the center speaker, in most cases, will clack or be damaged. in any case, who knows what is yet to come with both formats?

as far as 20hz capable floor standers, i've never heard one. in fact, most subwoofers don't display useful spl at that freq or below. how is it that a subwoofer can augment a full range speaker?

if you're attempting to make, say, 4-ways out of your front left and right 3-way speakers by splitting those 2 channels through 2 subwoofers, that, by itself has nothing to do with bass management. also, if the 2 subs are not each equidistant from the listening position with the front speakers, you have phase problems.

though i agree that multiple subs are easier to place in a given room, 'place' is the key word. they can't be placed just anywhere. the point i tried to make, is that the 5 satellites cannot be moved around the room, rather, their placement is very critical to a successful surround soundfield. placement of a sub is not the same as placement of a full range satellite. 5 'full range' satellites cause phase anomalies...period. we've tested and verified this fact.

which discs do you believe contain 'stereo' bass information? maybe i could benefit from an explanation of 3 subs and how they deliver stereo bass when summed with LFE (this is no sort of loaded question, i really would like to learn more about your setup).

the point of my previous post was in answer to a question from a self proclaimed novice and the subject of the thread is the 950's analog BM and connection of sacd/dvd-a players to the 950, not a list of the 950's shortcomings. i remember being absolutely cross-eyed at the whole BM situation...industry-wide...not just the 950. a simple 'place to start' is required. i found it in this forum and appreciated it very much.

SH is waiting for a uni player that suits him.

Kevin - I would consider my speakers full range.
Front - NHT 2.5i biamplified with a spec of 29Hz -3db. Each front speaker is also augmented by it's own NHT SubTwoi with a spec of 21Hz -3db.
Rear - NHT 1.5 each high passed through it's own Polk PSW650 28Hz -3db.
I run these speakers this way because when bass is coming from front left, I want to hear it come from front left. I have read and heard people say that bass is omni directional and I don't believe it. Just listen to good old straight stereo with subs in stereo and while listening unhook one and you will notice the difference. With my set up I can also make the subs mono or stereo and stereo is far superior IMHO.

Exactly what I want, left from left, right from right. This is especially true when playing DVD-A/SACD where bass can be coming from anywhere. Example would be playing something multichannel and a bass guitarist playing at your rear left and only the +80 HZ coming from that speaker and the -80HZ coming from a single sub in front of you in an opposite corner. It seems people spend most of their money on speakers to try and get this great sound stage with depth and width and then try and squeeze an entire section of frequency into one box in a corner. I went a different route with my speakers and IMO the BM on the 6ch input really hurts the potential for DVD-A/SACD through those inputs.
As a side note concerning this 20Hz figure. My youth was spent listening to lots of rock way to loud and this showed me something while testing the frequency response of my setup. I was playing individual test tones using the SPL meter to get readings. My 9 year old daughter was sitting in the room with me wondering why I would sit there and listen to these stupid sounds. Anywho when I start off at 20Hz I cant hear the noise only the various items rattleing throughout the house. I could feel the bass but couldn't hear anything until 30Hz. The same was true on the upper end with 18kHz being my upper limit. I mention my daughter because she could everything (20-20k)even at low volumes. My point is now I don't care if my speakers will play 20Hz or 20kHz at 120db because I can't hear it, but what I can hear in between sounds good.
Don't forget STEREO subs, it's worth it. SVS should love me

bosso - I agree that full range can be sent through all six channels but my limited DVD-A collection has not shown that in most cases. I also 'think' that most of us are not listening to everything at reference levels at all times so feeding those not so "full range" speakers a frequency they can't produce doesn't hurt anything as long some discretion is used with the black knob.
Just a difference in the definition of a "full range speaker". I usually consider a speaker full range if it can produce healthy bass below 40Hz. Maybe if I explain the front sub setup it would help. My NHT subs need to be handled by a controller. Each sub has just an on/off and an RCA feeding the amp. The controller allows for line level as well as LFE inputs.(also speaker level) You can high pass through the controller but I don't, that is handled somewhere else. Anyway the controller allows you to adjust main volume(line level inputs) and LFE gain independently for mixing in the desired amount of LFE. Low pass for each is handled seperately. So I take the front L/R outputs from the 950 split them one going to the sub controller and the other going to seperate sub amps driving the lower sections of the main speakers. I listen to most things with front speakers set to large.The full range signal used by both the mains and the sub with the sub low passed at around 40Hz allowing it to "augment" the deepest bass as the mains start to drop off in repsonse. The rears each pass through their own sub which is high passed at 80Hz making each of them acting as "full range". The rears are being fed with speaker level inputs so if I were to activate the 950's BM I would essentially remove all bass from the rears. Each speaker is in close relation to it's sub so they act as an entire unit making placement easier to me.
As for specific stereo bass on any songs I will have to go through and check but again I 'think' there is stereo bass in most recordings, maybe not a lot of seperation but can notice it quite often. It's subtle but it's there.
I also consider myself a novice and am thankful for this forum. This forum IS the reason I bought the 950/770. I was not looking for a way to point out the 950 shortcomings but following the original posted question of the correct way to hook up a 47a and I think the BM issue needs addressed for this. I hope tekdredger buys the 950 and trys it out for himself. I think given everything he will be very pleased.

keta: thanx for the details. i understand now some things i could only guess before.

the solution to your dilemma with this setup is a simple one:

since, when you switch to 6 channel bypass, you are only using the 950's preamps section, you can take the player's analog sw output and run it into a separate preamp (you can use a mono mic preamp and they start at about $65, but i would use a better one. see behringer shark or art @ zzounds or use any preamp you might already have lying around). from there you can input it into your controller. switch the 950's BM to 'off'. since there is no longer anything plugged into the 950's sw output, there will be no double bass and the system will work as you want it to.

when you switch to a digital source, the question will be: does the analog output of the player get the lfe signal, or the digital connection, or both? if your player sends the lfe to both or the analog output, you're good to go with all formats.

as far as protection of your center speaker, use caution with sacd discs. some send serious bass to the center.

also, i highly recommend consulting KCB about phase issues. this is a very important tweak in a system like yours and kevin has it locked.

i appreciate your input.

Keta- Where do those specs come from? The manufacturer?

I'd have more faith in them if it's either from a Stereophile speaker review, or if you go to the louspeaker reviews here with the NRC logo, they also have comprehensive measurements:

www.audiovideoreviews.com

I used to lust after stereo subs too. But with the interference effects across the room, and the fact that bass below about 80 Hz is omnidirectional anyway (doesn't matter where you put the sub, the bass seems to come from "everywhere"), just makes them more hassle than they are worth IMO.

Oh yeah, if you *don't* think low freqs are omni-directional, play your favorite panning effect with low freqs and the crossover engaged. But turn off power completely to your high passed mains. I guarentee that you won't be able to tell where the bass is coming from. Turning off power to your mains eliminates the higher freq components that provide the "cues" with which you think you are hearing the directionality of the low freqs. THX didn't pick the 80 Hz crossover for nothing...

Here's the link to the analyzer software I use with my PC:

http://www.etfacoustic.com/

The demo is free. I heavily recommend it if you haven't done this kind of analysis for your room. It's an eye opener... I used to use a Radio Shack meter with a discrete test tone disc too. This is much faster. And because it's so much faster, you can do a lot more plots that *really* investigate what's going on in your room.


[This message has been edited by Kevin C Brown (edited March 07, 2003).]