Seaton Sound SubMersive1 - Page 267

Quote:

Originally Posted by craig john 

Reducing the size of the Y axis will have the effect of making the tracing "look" flatter. However, all the same information is contained in both graphs.
So, yeah, the compressed Y axis in the OmniMic graph will make the result "appear" smoother.

Oh yes - it's just an optical illusion. It does make it a little harder to compare an OM graph with a REW graph though.

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(Aside: I once peer-reviewed a paper on "pulsatile flow" from another perfusionist. He compared two blood oxygenators for their ability to transmit a pulsatile waveform. He used two different Y axis scales to demonstrate the comparison. A cursory glance made the two waveforms look very similar. A closer inspection showed they were entirely different. He had "stretched" the Y-axis on one of the oxygenators to make it look like it did a better job of transmitting the pulse wave than the it actually did. I caught the "error" and made him change the scale of the graphs so they were identical. The paper was eventually published, but his "conclusion" was also changed.   )

You can't take your eyes off them for a minute ;)

 

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Nonetheless, that OmniMic graph you posted earlier was a better response. On it, you were +/- 6 dB from 50 to 100 Hz. On the above graph, you're more like +/- 10 dB from 50 to 100 Hz. And the +/- 10 dB shows on both graphs, whether the Y axis is compressed or not.

Interestingly, the "shapes" of the curves are not that dissimilar:

Yes, it was definitely a better graph. That is what mystifies me. The only thing that has changed since the OM graph was made is that I added 3 of GIKs 242 absorbers - I can't imagine they have made the difference shown, but just in case, I removed them and measured again and the result was the same. Only thing that makes sense to me is that the OM and the REW mics are sufficiently different to cause the difference. 

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They both show a pretty smooth response below 50 Hz, the same bump between 50 and 60, a recession in the 60's, and another bump around 70. However, you are currently losing more from there to 100 Hz than you were before. (Of course, the top graph is speakers and subs; the bottom graph is just the subs, right?) Are you sure they are the same 1/24th octave smoothing? A graph that is lower resolution will "look" smoother than a higher resolution graph.

Craig

They are definitely both 1/24th smoothed. But that's a good point - the top graph is almost certainly speakers and subs - the bottom graph is subs only. For comparison here is the current setup with speakers and subs to make a direct comparison more sensible:

Still not as good as the OM graph but much more similar.

And here in the more 'squashed' OM format:

Quote:

Originally Posted by craig john 

Quote:

REW tells me that it can do this to the top trace with 7 filters in the Behringer:





We shall see

Yeah, I don't see the narrow steep nulls you had before. These look more like "recessions" than nulls. The Behringer may well help with that. How much boost does it suggest?

Craig

Here are the filters - I can probably do better than this when I do it 'for real' and perhaps get a better result and/or use fewer filters. I limited it to a max 6dB boost.

@KB:  Since you'll have all the gear out on Monday, I would be interested to see some OM vs. REW comparison graphs at similar resolution and graph scale.  Heck, for that matter I think you can even import the .frd file of the frequency response from OM right into REW for a direct comparison!  Also, if you are willing to get the OM mic out for some measurements, any chance you could check that issue I had here with respect to PLIIx and the OM test disc?  I suppose it would be better to post the details in the USB mic and REW thread for more relevance.

Quote:

Originally Posted by craig john 

Looking at the filters, the only ones that will help you are the ones below 100 Hz. The rest would be above your crossover and will have little effect, (the one at 106 might have some impact, but above that, the major portion of the sound will be coming from the speakers and the PEQ won't be applied to them.)

Anyway, good luck and have fun!

Craig

Excellent point thanks Craig. How about this then - 

And only four filters this time - result up 100Hz is almost identical to the earlier one:

I'm just playing around with it ATM.

Quote:

Originally Posted by jkasanic 

@KB:  Since you'll have all the gear out on Monday, I would be interested to see some OM vs. REW comparison graphs at similar resolution and graph scale.  Heck, for that matter I think you can even import the .frd file of the frequency response from OM right into REW for a direct comparison!  Also, if you are willing to get the OM mic out for some measurements, any chance you could check that issue I had here with respect to PLIIx and the OM test disc?  I suppose it would be better to post the details in the USB mic and REW thread for more relevance.

Hey Joe - sure. I am only planning to do the Audyssey calibration on Monday. But I can do the PLIIx test for you with the OM test disc. Which OM disc do you want me to use for the test - the original or the later one with the additional channel tests?

Later in the week I am planning to do some more REW work, so I can also double check with the OM setup for differences etc - good idea. 

Quote:

Originally Posted by kbarnes701 

Quote:

Originally Posted by jkasanic 

@KB:  Since you'll have all the gear out on Monday, I would be interested to see some OM vs. REW comparison graphs at similar resolution and graph scale.  Heck, for that matter I think you can even import the .frd file of the frequency response from OM right into REW for a direct comparison!  Also, if you are willing to get the OM mic out for some measurements, any chance you could check that issue I had here with respect to PLIIx and the OM test disc?  I suppose it would be better to post the details in the USB mic and REW thread for more relevance.

Hey Joe - sure. I am only planning to do the Audyssey calibration on Monday. But I can do the PLIIx test for you with the OM test disc. Which OM disc do you want me to use for the test - the original or the later one with the additional channel tests?

 

Later in the week I am planning to do some more REW work, so I can also double check with the OM setup for differences etc - good idea. 

Keith, my issue was with the original OM test disc (track 2, monophonic short sine sweep).  I didn't keep OM long enough to get the new $20 test dvd!  Since using REW though, I can report no audible output coming from the surrounds in PLIIx mode.  No rush on the comparisons...just wanted to ask while you had the gear out.  It might be interesting to save the FRD files and import them into REW just to see how they compare to actual measurements.  If we wanted to get real tricky, since you don't have a 90 degree cal file, you could just use the OM mic in REW and take the same measurement in OM and REW.  That would eliminate another variable (the mic).  Anyway, thanks!

Quote:

Originally Posted by craig john 

How do you plan to connect the Behringer? I'm not completely familiar with it. Does it allow you to EQ the two subs separately or does it combine them and apply one set of filters to both? If it combines them, you'll lose the ability to set different Levels and Distances in the pre/pro. In fact, you might be better off running one subwoofer output to the Behringer and then running the subs as combined off the Behringer. When I had my SMS-1, that is how I did it.

OTOH, if it EQ's them separately, it will make the task much harder. The only response you *care* about it the combined response because that is the response you'll "hear." If you EQ each one individually to be flat and then combine them, you'll probably no longer be flat. So you'll need to set filters on one, but measure the response on the combination. Then set filters on the other, then measure the combination.

It's really fortunate that you so love taking these measurements.

Craig

$64,000 question Craig and the answer currently is IDK.  The Behringer is very flexible. It allows me to EQ the two subs separately creating separate filters for each, or to EQ them as a pair, with one filter set  (that is two channels on the Behringer with identical filters in each).

I am not sure I am understanding you correctly. Let me explain what I am thinking of doing. I am measuring the combined response of the subs and creating a graph of this in REW. I then use REW's EQ feature to make a filter set to apply to this combined response. I upload the filter set to the Behringer and it will create identical filters for Channel 1 (sub 1) and Channel 2 (sub 2).

The Sub outputs on the AVP will be connected Sub 1 to Ch 1 on the Behringer and Sub 2 to Ch 2 on the Behringer. The Behringer Ch 1 and Ch 2 outputs will be connected to Subs 1 and 2 respectively.

In this way, the AVR is still seeing two subs and outputting to two subs but it now has the Behringer 'in between'. 

I will still, AIUI, have the ability to change sub distances and levels individually for each sub. However, if I do this will it upset the FR determined by the filters already applied?  I know that the distance tweak, for example, makes a significant difference to the smoothness of my combined sub response, so losing the ability to set the distances individually would be a backward step. Similar for the levels. However, I was thinking that so long as the levels and distances are the same before EQing as they are afterwards, this will be 'neutral'. 

IOW, because I initially measured with the distances set to 11.6 and 9.6, and the levels set to (say) -7dB and -7dB, if I set these distances and levels in the AVP after applying the filters, will this not then be the same thing?

If the answer to that is 'no' then I would probably have to Y cord the subs and treat them as one.

Is my thinking correct on that?  HELP!! :)

In fact, I loathe taking the measurements believe it or not. My hobby is movies not graphs!  I see it as a necessary evil (but a useful one) :)

Quote:

Originally Posted by craig john 

Quote:

Originally Posted by kbarnes701 

Hi Craig,

The trims were all but identical anyway - within 0.5dB of each other IIRC. And even if I don't recall correctly, without checking, certainly no more than 1dB apart. But I take the point. I am definitely no longer calibrated  The bass is too loud (but it's kinda fun for a day or two - I don't do Audyssey cals and measurements over the weekend out of deference to Mrs Keith and her angel-like patience). On Monday I will run Audyssey (again!) and see what the trims are and do the divide/add thing to make them equal. It won't be too painful as I don't need to do a new calibration as such - just enough to discover the sub trim settings - as these are only measured from the first mic position at the MLP, I’ll just run the minimum number of positions, upload the result to the AVR, make a note of the trims, then reload the last full calibration, changing the trims to the new, correct, difference-split settings. Does that sound like a good plan to you?

Yup!

Quote:

Originally Posted by kbarnes701 

I should have gain-matched the subs ages ago TBH. No other way makes sense IMO when you have identical subs.

I know this is the SubM thread but with all this talk about gain matching and Audyssey, I have a question.  If you have two identical subs then presumably setting the gain to the same level on each would imply they are gain matched?  Is the process of measuring them both at the same location and same SPL just more precise?  On a similar note, I have an older 2-ch McIntosh amp (MC2205) that I'm using to drive my L and R channels.  I have a somewhat newer vintage MC7205 5 ch amp that I use for center and surrounds in a 7.1 system.  When I set the gain controls on the L/R channels of the two channel amp prior to running XT32, I played test tones through each speaker and adjusted the gain on the L and R channels until the SPL at the MLP matched my non-adjustable C channel at the MLP (all prior to doing a calibration).  I'm now under the impression that what I actually did was to level match the L/R to the C?  Is the thought process the same with other speakers being driven with amps that have separate gain controls and should I be doing the same thing with my L/C/R (all are MK Sound S150 II's) as Craig John has spelled out here with respect to gain matching two identical subs?  In this case, since I can't control the center channel gain, would I start with it in the center of the room, play the test tone, measure SPL and then repeat for the L/R and adjust the gain of each until SPL's match the center?

Quote:

Originally Posted by craig john 

Your pre-Audyssey level-matching step combined with the level-matching done by Audyssey is all you need to do. Gain-matching is unnecessary for the speakers. Most of the time they're not carrying the same content anyway.

Craig

Thanks Craig!

Quote:

Originally Posted by craig john 

Like I said, I'm not that familiar with the Behringer. I wasn't aware it had that much connectivity and functionality. Sounds like your plan should work just fine.

Phew!  Thank heavens for that :)  I based it on Audyssey - I figured that if Audyssey created one set of filters for both subs, then it would be OK for me to do the same, preserving the same post-EQ/Audyssey options I have always had - ie independent setting of trims and distances.

The Behringer is an amazing unit for the cost (under $100). Not only does it fulfil its primary role of killing feedback at live events but it also has two independent channels, can create 12 filters for each channel, allows the channels to be independent of each other or 'coupled', has 10 presets where you can store up to 24 filters (12 per channel or 24 for one channel or 12 per two coupled channels), has a simple MIDI interface which allows it to work seamlessly with REW and a nice informative display panel. The 12 filters per channel are, of course, adjustable for frequency, bandwidth and gain. Having the 10 presets makes it easy to create up to 10 filter sets, via REW, for testing purposes, and easily switch between them while measuring the results. And of course, if you want to store different FR profiles for, say, movies and music, then you can recall them at the push of a button.

The only downside I can see, so far, is that the unit is pig-ugly, with a brushed aluminium fascia. But as mine is hidden in a closet, this matters not one bit.

All I have to do now is figure out how to use it ;)

Quote:

Originally Posted by Ashi777 

Submersive.jpg 136k .jpg file

Hi guys,

Sorry for interrupting in your discussion. I guess have a question of a fairly peculiar nature.

I have a black maple vaneer finish on my submersive, and I was wondering what the best way is to clean it. It attracts fingerprints fairly easily and its quite tough to get them off. (Don't get me wrong, it looks beautiful 99% f the time ) I use a very very damp cloth to clean it but it really doesnt seem very efficient. Any other effective way of cleaning it? I want to be as careful as possible so Ive stayed away from any sort of solution or cleaning agent.

And also, should I be concerned if the sub is sitting in direct sunlight? The amp gets somewhat warm on a sunny day, of course it is turned off. There is a kind of translucent curtain which stops any direct sunlight getting to it, but its still gets to it. Ive attached a picture to illustrate this.


I know this question may seem pretty silly, ridiculous even, But I want to make sure I am taking the best care of my Sumbersive as I can

Thanks for bearing with me!
Ash

Hi Ash,

I use spray polish on my black maple veneered Submersives - the one we get in the UK is called 'Pledge' but IDK if that is available where you live. It is just furniture polish in spray form. I spray a little onto a soft cloth and then just polish it into the surface. The stuff is made for wooden furniture so it ought to be great for a veneered Submersive.  I would avoid a damp cloth as water or damp could conceivably get into the veneer through any small, natural splits in the veneer - this could cause problems with the bonding agent (glue to me and you) and it could lose its grip over time. What you have to remember is that veneer is natural wood - just in a very, very thin, well, veneer :)  So treat it like you would any other natural wood. 

WRT to sunlight - as you probably know, natural wood left in sunlight will go darker over time. As black can't really go any darker, then the sunlight won't change the appearance of your sub. For those with paler veneers, they need to be careful that if the sub is in sunlight it is ALL in sunlight and not just one side for example. In the latter case, they will eventually end up with a 'two tone' finish. The sunlight itself shouldn’t harm the veneer unless it is very hot sunshine. That is best avoided because it can cause the natural wood to dry out and possibly split. The polish I suggested should help 'moisturise' the wood which should help prevent it drying out anyway.

The amp won't be affected by sunshine. I am sure it gets a lot warmer when it is running hard ;)  I leave my amps on permanently - their design means that Mark's amps use barely any more current when left on than many models do when in standby. There is no downside to leaving an amp on. I have a two channel Class A amp in my music system that has been powered on for over 20 years with no harm. (I leave it on because until it has warmed up thoroughly it sounds harsh, and warm up can take 30 minutes or more, so I just leave it on and it is always ready). 

Quote:

Originally Posted by Ashi777 

 

Hey Kbarnes,

Thank you very much for your input.

The problem is I'm no expert on how natural wood works. The only time I've ever had an issue with natural wood is when I severely swelled up the toe of my cricket bat whilst playing on a wet pitch.

So I've always been super careful around wood since then.

I should be able to find a similar furniture polish. But now I am assured that I can use something like that on my sub.

Nice to hear that the sunlight won't be affecting my sub. That was the best spot I found for my sub.
By the way it sounds like you have a very very good amp there.

Thanks for the help Kbarnes!
Ash

It's good to see someone who cares enough to look after his gear.  The Class A amp is lovely - the only 'downside' to it is that it generates a lot of heat - but that's only a problem in the Summer.  As I live in England, that means it's only a problem for three or four days a year and I can live with that ;)  The rest of the year, we can turn down the heating in that room and the amp doubles as a room heater :)  I will never get rid of this amp while it is still working (and based on its history so far, it seems that that will be for ever). 

Yes, water will do that to a cricket bat if it gets into the grain. All it takes is a tiny split. 

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Originally Posted by Hudda 

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Originally Posted by kbarnes701 

I use spray polish on my black maple veneered Submersives - the one we get in the UK is called 'Pledge' but IDK if that is available where you live. It is just furniture polish in spray form. I spray a little onto a soft cloth and then just polish it into the surface. The stuff is made for wooden furniture so it ought to be great for a veneered Submersive.  I would avoid a damp cloth as water or damp could conceivably get into the veneer through any small, natural splits in the veneer - this could cause problems with the bonding agent (glue to me and you) and it could lose its grip over time. What you have to remember is that veneer is natural wood - just in a very, very thin, well, veneer   So treat it like you would any other natural wood. 

WRT to sunlight - as you probably know, natural wood left in sunlight will go darker over time. As black can't really go any darker, then the sunlight won't change the appearance of your sub. For those with paler veneers, they need to be careful that if the sub is in sunlight it is ALL in sunlight and not just one side for example. In the latter case, they will eventually end up with a 'two tone' finish. The sunlight itself shouldn’t harm the veneer unless it is very hot sunshine. That is best avoided because it can cause the natural wood to dry out and possibly split. The polish I suggested should help 'moisturise' the wood which should help prevent it drying out anyway.

I wouldn't use anything like Pledge. These oily polishes make things shiny but also build up into a goopy mess. Depending on the finish coating used, it can also rot the surface fibers of wood. Better to use something like a low-fingerprint inert wax once a year and then just buff it in between.

BTW, direct sunlight actually bleaches natural wood.

Chris

All I can say is I've been using Pledge on speakers for decades and never had a problem of any sort. Of course I don't use it every day and I apply it sparingly. Wax would be fine too of course. 

The colour change of the wood when exposed to light depends on the original colour. Dark woods tend to get lighter but light woods always get darker. Cherry gets really dark when exposed to sunlight. Cedar, redwood etc get lighter. The 'paler veneers' I mentioned will get darker if exposed to sunlight.

Quote:

Originally Posted by craig john 

I can't stand this constant bickering on the Submersive thread anymore. Damp cloth vs.Pledge vs. wax vs. dry cloth? What's next, GaryJ telling us to use Murphy's Oil Soap??? The BeeMan telling us to use bee's wax??? Where oh where will it end???

You guys should just do what we do... let the dust build up for a while and then invite the grandkids over. We have 3 Submerives and 3 grandkids, so each grandkid gets a Submersive. It's a game to see who makes the best design in the dust, with a little prize for the winner, usually a dish of ice cream or a $100 or something. It's great fun and the Submersives always look different afterwards.

There is no need to keep the Submersives clean... just let your grandkids do it. If you don't have grandkids, just just get puppies or kittens. Any small mammal will do.

Craig

LOL!!!  Brilliant! "Any small mammal" Hahahahahahaha. 

Quote:

Originally Posted by audioguy 

I originally used some very high quality furniture polish but noticed that the cleaning cloth got black on it (I have black oak Catalysts).

Mark told me to use NOTHING but clean dry cloth and dust the speakers. So that is what I have done.

Nothing is always good advice I think. But it can be difficult to remove fingermarks with it.. ;)