Which EQ / room correction for me

dazed&confused

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I am interested in trying out an EQ or room correction device, having just ordered a BK XLS400DF subwoofer which I will be using for stereo use at high level (speaker level) as well as for movie and for multichannel music using the low level LFE connection.

Whichever EQ/ room correction device I try, ideally it will work both for stereo use and for AV use because my current AV receiver has no EQ/correction itself and because I am interested in replacing my AV receiver with an Audiolab 8200AP or similar, which also has no room correction.

I am thinking that I might be forced to try an EQ/correction device which works only for the subwoofer, not for the stereo speakers as well, because of my particular set up. However, I would prefer to try a device that would also work for the stereo speakers because I am thinking of changing my current stereo speakers (which have a specified frequency response down to 45Hz) for a pair with a frequency response down to about 30Hz.

In my set up the subwoofer will always remain in the same location in the room but - weird I know - I move my front stereo speakers around the room depending on whether people are sat just on one couch or on two couches and, in the case of just the one couch, whether it is for “everyday listening” or for “critical listening”. Thus, if I were to try an EQ/correction device that worked for the front stereo speakers as well as for the subwoofer then it would have to have memories for at least three different basic, initial calibrations using the microphone – not just for different post-calibration “house curves” such as “neighbours at home” and “neighbours not home”, etc.

My equipment set up regarding the signal path is as follows. In stereo use the AV receiver is switched off because my sources (currently an analogue out from a universal disk player and an analogue out from a DAC) go straight into my Townshend Allegri “Passive Preamplifier”, which goes to Cyrus power amps, and the BK XLS400 subwoofer will be connected at speaker level using the Neutric connection. For movies and multichannel music my AV receiver pre-outs are bypassed through the Townshend Allegri (set at 0Db attenuation) into the Cyrus power amps and the same BK XLS400 subwoofer will be connected at line level to the LFE out from the AV receiver. The Allegri preamp has RCA outputs only (no balanced outputs) and my current Cyrus power amps have RCA inputs only.

I would like to try an Anti Mode Dual Core, which I am told has four memories which can be used for different basic, initial calibrations. However, from what I can tell, one needs to use the balanced outputs of the Anti Mode Dual Core in order to apply it both to the stereo speakers and to a subwoofer and, even then, I can’t see how one would also connect the LFE output from the AV receiver through the Anti Mode into the same sub.

Could anyone tell me how the Anti Mode Dual Core would fit into my system and operate as required? Any suggestions for an alternative EQ/correction device? Perhaps I would need two separate devices, one for AV and one for stereo? Or perhaps there is a simple, multi-channel preamp/processor that is similar to the Audiolab 8200AP but with built in EQ/correction, which would work in tandem with something like the Anti Mode Dual Core connected separately for stereo use?

Or maybe I wouldn’t even have a notable benefit from EQ/room correction applied to frequencies of 30Hz and above?


Additional information -

My room is about 5.2m long by 3.4m wide by 2.3m high, with the front speakers firing across the width of the room and occupying up to just over half of the length of the room. The remaining part of the room has a dining table small dining table and chairs. I would describe the room as cluttered since I have also squeezed in two couches, an armchair, a couple of large cabinets, and book shelving. In other words, there are many “randomly placed” solid and semi sold surfaces at varying angles. The floor is engineered wood on top of thick underlay on concrete scree but I have made some use of rugs and I have curtains as well as venetian blinds on the two windows. In addition to a standard door on the long wall with the speakers, behind the dining table the end wall has 1.4m wide sliding doors opening into the kitchen.

Many thanks for your input,

David.
 
You have a complicated setup! A block diagram of your system would probably help :D

I have to ask though..... why do you move the speakers around?
 
Hi Matt

Thanks for your reply

Just think of it as the simple, common set up of an AV amp's pre-outs going through the "AV bypass" of a stereo amp. I guess there might be a complication by having two connections into the sub woofer but this is also common I believe. I'm afraid I don't know how to put a diagram on here.

The main reason I move the speakers is that the two couches are set at about 110 degrees of each other, and the best compromise is to have the speakers equidistant of the apex, firing toward the point at which the two couches meet. Most of the time there is just one or two of us (sat on the one couch) so I just fire the speakers directly at that couch. In this set up, if people were on the other couch then they would be right at the edge of the sound field.

Even for people on the best couch, with the speakers firing straight at them, in the "everyday listening position" one of the speakers is very close to a side wall and the front of the armchair protrudes slightly in front of the inside of this speaker. Hence, for the "critical listening" position, the armchair is moved to a different part of the room and the speaker is moved inwards from the side wall.
 
I'm going to take this speaker moving exercise as a given and consider the practical impact of that only (i.e. I find it hard to conceive of how that is worthwhile but it's your room/setup so go for it!).

How far do you move the speaker?
How careful are you at putting the speaker back into position?

The problem you have is that EQ is naturally EQing to a particular location, i.e if you move things around then the EQ you apply may no longer be valid. However, at bass frequencies, minor positional changes have little impact (as long as the distance you move is truly insignificant compared to the wavelength of the frequency you are EQing).

The other problem you have is that moving a speaker meaning changing the correct time alignment. If you get this wrong then you will reduce the quality of the transition from mains to/from sub. Again, small differences (say under a foot) are not critical, larger ones are.

I'll have another read of your actual setup in a bit.
 
Is this correct? solid line = AV, dotted line = stereo

Is this 5.1 or 2.1?

upload_2014-9-22_13-0-30.png


The 1st problem is that I don't know of any EQ devices that accept a high level input so the only way I can see to fit EQ into that picture *without changing the preamp/amp connections* is to put it between a single source and the preamp. You could do this with a big enough minidsp (miniDSP 10x10 Hd | MiniDSP if you really wanted to but I don't think it makes an awful lot of sense.

I think your choices boil down to

- replace the AVR with something that has EQ built in & bass manage everything (i.e. get rid of the high level sub connection) & stop routing things directly to the allegri
- don't EQ the music setup and put a basic antimode or minidsp 2x4 between the AVR & SW
- don't EQ the AV setup and put an antimode dual core or minidsp 2x4 between the allegri and the cyrus

No great choices as far as I can see.
 
Hi Matt

First of all, thank you so much for taking the trouble to do a diagram. Yes, you got it my signal path and set up exactly correct. For anyone else who is reading this thread and might be wondering, the connections between the Allegri preamp and the Cyrus power amp are one and the same - the lines in the diagram are just for illustration purposes to show the signal path; there are not actually separate leads for AV and stereo between pre and power . The same goes for the connections between the Cyrus and the main speakers.

Regarding my moving my main speakers to different positions, can you just take my word for it that this makes a HUGE differences to the quality of the sound stage? Perhaps I should also add that the plasma display is on a swing arm and varies position, such that the speakers need to be moved to be equidistant of the screen.

I'm not getting your argument that "if you move things around then the EQ you apply may no longer be valid" and that "moving a speaker means changing the correct time alignment, which will reduce the quality of the transition from mains to/from sub". This is precisely my reason for asking for an EQ device with separate memories for separate calibrations. Although I will move the speakers around I will always place them accurately so that, by selecting the appropriate memory for their position, they will always be in exactly the position that they were calibrated in.

Could you clarify whether or not the Mini DSP range of devices have separate memories for separate calibrations, like the Anti Mode Dual Core does?

Regarding "the 1st problem is that I don't know of any EQ devices that accept a high level input". I think my question about this has turned out to be a bit of a Red Herring. Having though about it some more, my clearer understanding now is that the sub woofer actually becomes an irrelevance to EQ when it is connected to the main speakers at speaker level. I'm thinking that if an Anti Mode Dual Core were being calibrated then it would just see the sub woofer as being part of full range speakers that happen go down to a very low frequency.

Something else which has since occurred to me is that, when I am using the LFE sub connection, the main speakers will be set to "small" and crossed over somewhere between 50Hz and 80Hz. Hence, for AV use it may be that I will only need EQ applied to the sub woofer, not to the main speakers as well.

I'm thinking of using your "don't EQ the AV set up" solution but instead of putting the Anti Mode between the Allegri and the Cyrus I could put it between the sources and the Allegri. I've not yet got around to splashing out on an expensive DAC and it may be that the one in the Dual Core will be good enough. My budget Arcam DAC can then be relegated to the bedroom.

The main speaker pre-outs from the AV receiver or processor could then go straight into the Allegri, in the same way that they do already. I could either invest in an AV receiver with its own equalisation using the high level input of the sub woofer or I could invest in a second, second-hand Anti mode to just equalise the LFE output - hence just a basic Anti Mode rather than a Dual Core.

Can anyone see any problems with this solution?
 
Regarding my moving my main speakers to different positions, can you just take my word for it that this makes a HUGE differences to the quality of the sound stage? Perhaps I should also add that the plasma display is on a swing arm and varies position, such that the speakers need to be moved to be equidistant of the screen.
for sure, that's why I said it's your room so do what you like :)

I'm not getting your argument that "if you move things around then the EQ you apply may no longer be valid" and that "moving a speaker means changing the correct time alignment, which will reduce the quality of the transition from mains to/from sub". This is precisely my reason for asking for an EQ device with separate memories for separate calibrations. Although I will move the speakers around I will always place them accurately so that, by selecting the appropriate memory for their position, they will always be in exactly the position that they were calibrated in.
it's a question of precision; how accurately do you put the speaker back in the same spot aiming in the same direction each time? minor discrepancies won't be an issue for bass eq. If you're careful then I doubt it will be a problem.

Could you clarify whether or not the Mini DSP range of devices have separate memories for separate calibrations, like the Anti Mode Dual Core does?
some of them do, the cheapest ones don't.

Regarding "the 1st problem is that I don't know of any EQ devices that accept a high level input". I think my question about this has turned out to be a bit of a Red Herring. Having though about it some more, my clearer understanding now is that the sub woofer actually becomes an irrelevance to EQ when it is connected to the main speakers at speaker level. I'm thinking that if an Anti Mode Dual Core were being calibrated then it would just see the sub woofer as being part of full range speakers that happen go down to a very low frequency.

Something else which has since occurred to me is that, when I am using the LFE sub connection, the main speakers will be set to "small" and crossed over somewhere between 50Hz and 80Hz. Hence, for AV use it may be that I will only need EQ applied to the sub woofer, not to the main speakers as well.

I'm thinking of using your "don't EQ the AV set up" solution but instead of putting the Anti Mode between the Allegri and the Cyrus I could put it between the sources and the Allegri. I've not yet got around to splashing out on an expensive DAC and it may be that the one in the Dual Core will be good enough. My budget Arcam DAC can then be relegated to the bedroom.

The main speaker pre-outs from the AV receiver or processor could then go straight into the Allegri, in the same way that they do already. I could either invest in an AV receiver with its own equalisation using the high level input of the sub woofer or I could invest in a second, second-hand Anti mode to just equalise the LFE output - hence just a basic Anti Mode rather than a Dual Core.

Can anyone see any problems with this solution?
EQ the LR line level feed will work just fine yes. For AV use though, you won't be EQ'ing the LFE channel or the centre/surrounds (if you have them, still not sure if this is 5.1 or 2.1). This is unlikely to sound v good. It's also not true to say that it is sufficient to EQing one side of the crossover.

Another option, v similar to the "get a new AVR option" admittedly but still, would be to move bass management into a sufficiently large minidsp & configure the AVR with all speakers set to large.

The fundamental question here is what is the point of the allegri here?. It seems quite pointless employing a "transparent" preamp (at least that is the marketing, I have no experience of the product) with a source connected directly to it, presumably to avoid the relatively "opaque" AVR, if you're then going to pass it through a device that then does an AD/DA to apply EQ. What source do you have connected to it?
 
The fundamental question here is what is the point of the allegri here?. It seems quite pointless employing a "transparent" preamp (at least that is the marketing, I have no experience of the product) with a source connected directly to it, presumably to avoid the relatively "opaque" AVR, if you're then going to pass it through a device that then does an AD/DA to apply EQ. What source do you have connected to it?

You seem to have misunderstood what I wrote Matt. My suggestion was to place the Anti mode Dual Core BEFORE the Allegri, not AFTER it. In this scenario I would be using the Dual Core just as a DAC with added DSP functioning for room correction - the preamp section of the Dual Core would either be bypassed (if it could be "£switched off") or it would be set at 0Db gain. Sources would be toshlink digital out from CD and USB digital out from music stored on computer. As I said, I would relegate my budget DAC to the bedroom and forget buying an expensive one.

The point of the Allegri would be twofold in this scenario: firstly it would allow me to bypass the AV front speaker pre-outs directly to my front speakers (via the power amps) without effectively going through two preamp stages or re-digitising - the Allegri set at 0Db gain is literally just a straight wire.

Secondly, with the Allegri connected I would have the Dual Core set at its optimum volume. This fits with advice given to me from the dealer from whom I purchased the Allegri. I was torn between spending my money on the Allegri or on an Antelope Zodiac Gold DAC, which is very highly regarded and, like the Dual Core, has a digitally implemented analogue volume preamp. The dealer assured me (I purchased on line) that the Allegri was superior to the preamp in the Zodiac and that a superior solution would be to run the Zodiac at full volume into the Allegri (although he wasn't trying to sell me a Zodiac as well as an Allegri).
Since then I have become interested in the idea, which you implied yourself in an earlier post, that room correction could offer more of an audible difference than a the difference between a £2500 DAC and a £500 DAC.

EQ the LR line level feed will work just fine yes. For AV use though, you won't be EQ'ing the LFE channel or the centre/surrounds (if you have them, still not sure if this is 5.1 or 2.1). This is unlikely to sound v good.

That's right - as I said, the AV would be kept entirely apart from the Dual Core. I did suggest that I could add a second hand Antimode 8033 to EQ just the sub via the LFE connection for AV duties, given that my main speakers would be crossed over at no less than about 60Hz. My AV system is 5.1 but I'm somewhat surprised that you say the it would not sound very good without also equalising the centre and the surrounds, as my understanding that EQ is only really effective for bass frequencies. Are we getting more into the realms of personal taste here? Or is it incorrect for me to think that a separately connected 8033 could EQ the LFE channel?


It's also not true to say that it is sufficient to EQing one side of the crossover.

I don't really understand what you're getting at with this point Matt. Could you explain please?


Another option, v similar to the "get a new AVR option" admittedly but still, would be to move bass management into a sufficiently large minidsp & configure the AVR with all speakers set to large.

By sufficiently large, I take it that you mean large as in number of channels the DSP has? Would a DSP used in this way have any advantage over an AV receiver such as the Marantz AV7008? How much would it cost including the software etc?
 
You seem to have misunderstood what I wrote Matt. My suggestion was to place the Anti mode Dual Core BEFORE the Allegri, not AFTER it. In this scenario I would be using the Dual Core just as a DAC with added DSP functioning for room correction - the preamp section of the Dual Core would either be bypassed (if it could be "£switched off") or it would be set at 0Db gain. Sources would be toshlink digital out from CD and USB digital out from music stored on computer. As I said, I would relegate my budget DAC to the bedroom and forget buying an expensive one.
I understood what you meant, I just didn't know what your sources were. I was working on the assumption that you had a high quality analogue source and were using the allegri basically as a volume control. Putting another AD/DA between that source and the allegri seems pointless to me but if you actually have a digital source then that's a completely different proposition.

I did suggest that I could add a second hand Antimode 8033 to EQ just the sub via the LFE connection for AV duties, given that my main speakers would be crossed over at no less than about 60Hz. My AV system is 5.1 but I'm somewhat surprised that you say the it would not sound very good without also equalising the centre and the surrounds, as my understanding that EQ is only really effective for bass frequencies. Are we getting more into the realms of personal taste here? Or is it incorrect for me to think that a separately connected 8033 could EQ the LFE channel?

I don't really understand what you're getting at with this point Matt. Could you explain please?
It's generally accepted that EQ can be successful below the transition frequency where the behaviour of the room is dominated by modal resonances, some of produce the same response across an entire listening position. As the frequency rises, such modal resonances get closer and closer together and get more and more sensitive to changes in position. Unless your run your sub with quite a high crossover (varies with the room but say >150Hz as a reasonable guesstimate) then both the sub and the main channels will be similarly affected and can be significantly improved by the appropriate use of EQ.

As to using 2 antimodes, it will certainly eq everything you want. How well they'll combine is another question. I don't know how similar the algorithm is in each device for example so it's feasible they would come up with different results. I imagine there are v few, if any, people doing that so it would be a case of trial and error.

By sufficiently large, I take it that you mean large as in number of channels the DSP has? Would a DSP used in this way have any advantage over an AV receiver such as the Marantz AV7008? How much would it cost including the software etc?
miniDSP 10x10 Hd | MiniDSP - about £420 inc a mic

a minidsp is completely under your control so you can do what you like with it.
an AVR typically has an automated room correction system of some description which you can't control at all (in the case of audyssey) or which gives some limited control (in the case of Anthem ARC).

You have to learn how to use the former, the latter is just press button and hope you like the results.

If you go for an audyssey equipped AVR then make sure it has XT32, anything less is a waste of time. The SR7008 does btw. Bear in mind that audyssey is all or nothing, i.e. all channels are equalised full range or they are not equalised at all.
 

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