Twin Servo 15's - 1st play

[Alaric]

Hi Guys,

Just had a quick play with my dual Servo 15's and here are some pics...

Mic-sc - Simple Mic & Sound Card Cal - Its EM8000 with Sharc110 preamp, the cards internal Realtek HDA on my MSI board

Left - Green b4, Red after

Right - Blue b4, Purple After

Both - Red B4 (filters defeated), Blue After

This is all just accepting the REW filter settings, so cuts only....Also its bypassiing my Amp as i can't think of a way of inputing via the amp, save the 6chanel bypass, which kinda defeats the object. The subs are at 1/4 vol on the plate, the amp is at -10db for the sub output, but both it and REW was calibrated for 75db on my SPL meter (RS), so that should work, although as such the PC vol was at 25% to get the -10db loss that my amp does .... I probably want to re-calibrate to 75db as i guess the BFD's cuts will lower the overall volume.

cya,
Lee

[brucek]

Also its bypassiing my Amp as i can't think of a way of inputing via the amp

Simply feed the AUX or CD input of your receiver........

Dual Servo-15's - yikes. I have just one and it rattles everything in the room........

brucek

[Alaric]

Hi Bruce,

CD or aux...I guess i would just get stereo, but since thats being fed through the same system settings and DD/DTS it should work. I even have a dual adaptor which means i can feed the same signal into L/R as i don't know if REW outputs on both chanels ??

So what do you think of the graphs...There seems a couple of nasty dips for my taste and REW's auto settings seem to make things more bumpy, although at a more reasonable average.

I obviously have tonnes of headroom being at 1/4vol and -10db down on the amp....Can i heavily cut those humps, say bring cut everything down to 64db and then increase the whole range back up ???

Dual servo's (the orig paradigm 15a's)....Yeah, why not. The amp has dual outputs so i should get some bass stearing (?), i have the space doing nothing and the second one was cheap(ish)...Its a little scratched but behind the screen, who cares ! The room is also a fair size (17'x11') so i figure its better to have two with loads of headroom than one being heavily pushed....I've also read a few articles that recomend multiple subs...I'll have to try and re-find them !

Ta,
Lee

[brucek]

even have a dual adaptor which means i can feed the same signal into L/R as i don't know if REW outputs on both chanels ??

Yeah, REW outputs the same mono signal on the right and left channel of the soundcard. Some people use a 'Y'-adapter at the receiver input and some use two cables from REW - same result. You set your receiver to stereo and set your crossover that you like and the sub out will be bass managed......

You normally have to manually play with the REW recommended filters and also add some of your own creation to get the results you like.

Can i heavily cut those humps, say bring cut everything down to 64db and then increase the whole range back up ???

Yeah, some people reduce the entire level down to the level of the dips and then add wholesale gain at the subwoofer itself to compensate, as long as you don't run out of signal. I would start with reducing the peaks and see how it looks. Your response looks pretty good though. Some small dips can go un-noticed when you listen. Resonant peaks usually stand out like sore thumbs.
I'd like to see the results with the crossover in place and also the target shown on the graph...

brucek

[Alaric]

Hi There,

Heres the article

http://www.onhometheater.com/features/20040801.htm

And the White paper it links to...

Basicaly it says that with one sub you can get ideal listening for a single position, but for more than just a single sweet spot you need more subs, upto a max of four. Idealy placed in the corners, but two in the mid position (back and front) is almost as good, for a 'normal' room.

cya,
Lee

[Alaric]

Hi Bruce,

The crossover is fixed at 90Hz on the Yamaha AX1.....IIRC the Z9 which i hope to upgrade to soon (when someone will sell me one) has an 80hz THX style crossover

The target is not selectable on the graph that gives comparisons, ie before/after....I think its only available for the current measurement, otherwise i'd have left it on.

I'll post some more later when i get a chance to measure again !

Ta,
Lee

[brucek]

but for more than just a single sweet spot you need more subs, upto a max of four.

hehe, good luck with that.....

But seriously, there's lots of debate on that subject. Some people have lots of luck with multiple subs, and the theory makes sense - just hard to pull off in reality sometimes.

A lot depends also on how wide a sweet spot you want. If you need a large area, I find that taking about eight different response sweeps at eight listening positions and then click the REW Average button creates a nice curve to create your filters with. Then everyone gets a decent response when the room is full. Then you can also have another BFD program for a single hot spot when you're doing critical listening.

The target is not selectable on the graph that gives comparisons,

You're right - my bad.

brucek

[Alaric]

Hi Bruce,

The room has two rows of seats, first row is a pair of lazyboy matinee cinema seats, One mine, one the wifes. We then have the second row of seats with 3 tilt up style cinema seats...I'm predominantly bothered with the front pair for ubersound as those are the most used...ie almost daily as we don't use a TV and just use the cinema instead.

I've just had another go with REW and i'm technicaly quite pleased

Before - Both subs (Red) as one trace, with target 764db 90Hz cutoff

Left - Left sub (yellowish) on its own, estimated corrected trace is dotted. The Target was brought low so as to attemt to equalise to a lower level, then boost the whole range

Right - Right sub (light blue) - Same as for Left

Left+right - Both together

Both b4+after - Both subs as one trace, before (red) and after (purple) with a 5.5db increase on the amp to bring things back to 75db average

All4 - All 4 measurements on one graph

Sub+Mains - A look at how the sub (corrected as above) and the rest of the speakers interact with Dolby PL (as its a two chanel source)...

20Khz - A quick sweep to 20Khz with 1/3 smoothing...As i have a set of rane equalisers to play with...A THX44 for the fronts and a SSE35 for the rears - but thats another day - Its listening time

cya,
Lee

[Alaric]

Hi There,

Just had a quick think and play with my data....I tried averaging the left and right sub traces and then compairing with the measurement of the two combined (dark blue)....spookily close !

[clubfoot]

Have you tried measuring at a different location,...say in front or behind the listening position?

[Alaric]

Hi There,


Just noticed three of the above graphs are incorrectly formated...How i managed that is anyones guess and hence looking at them they are a little odd.

I've had a day or so listening and there is certainly a difference (between my first equalisation and non), but i'm not sure its better. The bass is certainly fatter, but it seems a little wooly and masking....Its like the instruments are more equal and less distingusable.

Club - Nope. Just measured at my seating position. I really want to equalise for both the front seats, and also the reclined position, as to be honest we tend to be part reclined !

Cya,
Lee

[Alaric]

Hi There,

I just reloaded my data from the other day as i was going to re-post the graphs in the correct format as thats better for comparisons, however on reloading the colours are different, which then makes everything confusing !

Is there anyway in REW to change the trace colours manualy ? It would also be nice to rename the graphs on the left as ATM its just a date and time...This would be especialy handy for going back to the data a few months later. I'd also like to be able to add the Target trace onto the All Measured and Averaging pages if your interested in consumer tweaks John - Edit : It also seems the

Anyway. I've just done some comparitive measurements from the second seat. I didn't touch the PC's levels or my Sharks inputs and then set the volume so the sub cal was 75db again, so these should be close (for comparisons sake) to the above.

The two measument positions are Lee & Suzi, ie My seat and My wifes

Both Corrected Lee - Both Subs (blue) as one trace with the BFD filters set above engaged, at my seat

Both Corrected Suzi - Both Subs (Green)as one trace as above but for Suzi's seat

Both Corrected Together - The two above on one graph

Both Uncorrected Suzi - Both subs (purple) as one trace with the BFD defeated at Suzi's seat

Corrected-Uncorrected - A comparison of the uncorrected and corrected traces at Suzi's seat


I'm quite suprised that the corrected trace is quite similar for Suzi's seat as it is for mine, when the measurement is approx 2 foot closer to the wall and as such a lot more off axis from the speakers.

cya,
Lee