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One for the Isobarik Experts

Richard

Agree with the direction you are going in . I would just take time out to check that your listening position really is right for both you and the measurements ! I spent a fair bit of time last year with REW and my 3-6 naxo scratching my head . I found that I could get a fair approximation of a house curve by trimming the pots on the naxo , but what sounded good to the ear and what looked good on a graph did not always align. By moving mic position along the couch and altering height I found major variations. Had to admit in the end that that both the room (5m x 5m x 2.5 m !!!) and where we wanted to sit when added were too much of an ask . Hope you fare better. A tip with the naxo -- I took photos on my phone of trim pot positions and saved the pic with a note -- this allowed me to go back and forth on trim postions and listen for my preferred sound .

It will get better and be worth it -- I'm now in a differnt room with an exaktbox and it sounds great . Using SOv2 on 40/60 flat v decay response preference with little tweaking of ideal v real speaker placement . FWIW -- not minded to use REW here to check as we are happy with where the Bricks are and if the sound is good , I'm not going to start measuring -- until I mod my Briks to split the bass feeds :rolleyes:

As a side note --any tips on where to source 4mm sockets for the cabinets ? I'd like to make the extra pair match as close as possible . [I have a late pair of DMS with the colour coded sockets]

Enjoying your updates and finding the REW shots useful --please keep posting.

:)
 
Good Evening All,

Got back home this afternoon and have been pressing on with the Exactbox as I'm aware it is 'on loan' and being away from home for 9 days with it lying there unused..........

At Neil's request I went back to basics and Tune Dem'd the speakers location. I used Khmer by Molvær and Inception Time Live by Hans Zimmer as test tracks. Having slid the speakers here there and everywhere i.e. anywhere from 25cm away from the 'front' wall to only 1.5mts between tweeter centrelines and in and out.

I don't know whether expectation bias was creeping in but they ended up where they started i.e. 6cm off the front wall and 75cm from the side walls.

I then started a sequence of REW frequency sweeps starting at 30% of the room length all the way back to 70% in 5cm increments, as requested by Neil - tiresome to say the least. Having said this it was most definitely of benefit and I have sent a whole host of files to Neil for him to look at.

My own interpretation of the data gathered so far is that GIK's suggestion of sitting at the 38% location isn't the best place to be sitting. The sweeps in a previous post show a peak at 36Hz and a dip at 150'ish Hz, both of these become less obvious as you move towards the centre of the room.

sFHSkkb.png


The above sweep is, as you can see, taken 2.51mtrs from the front wall and, IMHO, is a good place from which to move forward. If you take the 65dB line as ground zero you can SO the peaks at 80 and 95Hz and then we just need to adjust the filters to bring the mid and high levels down but I have no doubt Neil will tell me it isn't that simple..........

Have moved my chair to the 2.51mtr position and modified SO accordingly. I haven't done a comparative sweep yet but I have to say the whole thing sounded a deal better than it did with me sitting at 1.78mtrs.

The Exactbox certainly seems to be doing things the SNAXO wasn't but then there is a Klimax DS driving things as well.......

I'm away again on Thursday so don't know when the next session with Neil will be.

Regards

Richard
 
As a side note --any tips on where to source 4mm sockets for the cabinets ? I'd like to make the extra pair match as close as possible . [I have a late pair of DMS with the colour coded sockets]

This question has been asked before and I don't think anybody has had an answer, mine came from scrapping a pair of Brik's but they must have been available at one time as I can't see that Linn would have had them made (although I have nothing to back that suggestion up). I want to keep the four I have left in case I do go the final step of splitting the tweeters.

Regards

Richard
 
I’d normally suggest that 6cm is nowhere near enough space behind the speakers and 6” is more usual. But you’re not using standard bass units so I’m well out of my comfort zone.

I applaud your spirit of adventure!
 
I’d normally suggest that 6cm is nowhere near enough space behind the speakers and 6” is more usual. But you’re not using standard bass units so I’m well out of my comfort zone.

Interesting........ I wouldn't have thought the make of woofer would make any real difference but who knows.

Any other Brik owning fishies care to comment on their preferred distance off the wall???

Does the pfm collective 'hive' (sad Trekkie reference) mind have any recommendations for good quality 90° banana plug should I want to try getting closer to the wall?

I’d have given up by now;)

I would too if I didn't feel progress was still being made. If Neil would have come up here and done the leg work I'm doing on his behalf it would be costing me a small fortune. The work Neil is doing comes at a cost as these are 'one off' speakers and its highly unlikely he'd be able to benefit from being able to sell the filters to anybody else. I'm fine with that as I knew from the outset this wasn't going to be a simple 'cut and shut' job.

I need to get the old NAXO 2-4 boxed up and out the door and then I can start cutting up my two Gunstig mats......... then I'll find out if thomasasking off A.N.Other forum method of isolation works for me.

s0CYuRs.jpg


tFXxvQ7.jpg


It's liberated 43 4 x 4 'squares' and 6 small neodymium magnets (more are somewhere in the cut up bits....)

I'll be playing about with SO after lunch....... more unbridled fun!!!

Regards

Richard
 
Good Afternoon All,

Just back from the post office and about to start on playing with SO.

Reference connectors for splitting drivers this is from a pair of Isobariks up on a well known internet auction site at the moment;

oOezJTt.jpg


I also note a seller down Ayrshire way wanting £2250 for a pair of Brik's very much in need of some TLC......

Regards

Richard
 
Good Afternoon all (again),

Just completed a couple of sweeps at 2.46mtrs, one with and one without SO v1 straight out of the box i.e. no alterations.

eRq6PV3.png


EXZJsNw.png


As you can see the impact circa 65Hz is a little 'savage' to say the least. Next up will be following Neil's advice and halving what SO wants to do......

Regards

Richard
 
Richard , can you indulge me in an experiment.

Can you put the speakers 7” from the wall, 66” in between with no toe in and show us the sweep.
 
Richard , can you indulge me in an experiment.

Can you put the speakers 7” from the wall, 66” in between with no toe in and show us the sweep.

David,

Well as my wife has put off the horse pooh picking until tomorrow then yes I can. Do you mean 66" between the cabinets or tweeter centre lines??

By the way are't we metric nowadays?????;)

Regards

Richard
 
66” in between cabinets, sorry for the imperial

David,

It's OK. I've just posted you the REW files and a screen shot of what SO is doing. For the benefit of others;

PH4saMg.png


a2PgIEu.png


The circa 160Hz dip has 'gone' of that there is no doubt. I've now got to go and see what it 'sounds' like........

Regards

Richard
 
David,

Interesting to run a few 'tunes' through the speakers in this away from the wall position. The sound is OK BUT if you give it the PRAT test then it simply doesn't cut it to my ears.

The stage width and depth increase the closer you get the speakers to the wall and the sense of involvement with the music rises. Taking the Linn philosophy of if it sounds better then it is.

one I have where there's an interesting depth of field check with two microphones a man's voice a triangle and some maracas... I'll see if I can remember what it's called, its good fun too.

I think you must be thinking of the IsoTek 'The Ultimate System Set-Up Disc' as this has the maraca's test tracks?

Regards

Richard
 
I’ve been using my DMS Isobariks since 1984 when they were installed by the Sound Organisation of Borough Market.
It has the original straight cannon sockets the back of the speaker is 4.5” from the wall ?

Regards,

Martin
 
It was only an experiment to see how the response reacted. The final position the speakers want to be in is most unlikely to be arrived at by guesswork.

my personal experience is that they never need to be further than 8” away from the wall but never nearer than 4”. But literally a 1/4” can make all the difference.
 
David,

I've read, more than once, this mantra of moving the speakers large amounts at first then ever smaller and smaller amounts until some kind of nirvana is reached. I can't dispute it as I'm not technically qualified enough to do so but I do raise a somewhat quizzical eyebrow at the suggestion that most people, in blind testing, could tell if a speaker was moved 1cm from one test to another.

I went from 25cm off the front wall and the speakers being 1.2mtrs apart, back and forth and in and out. 'It' (i.e. depth and width) starts coming together at 10cm off the front wall and 85cm in from the side walls. I've stopped at 75cm (not very far from your 66" between speakers which would make it 73.2cm) from the side walls (I could go further but would then have to drag the hi-fi stack clear) as 'it' just sounds right.

There was a width of stage at the position you requested and some depth but, as far as I could tell, there was a deal more of both in the original position.

If somebody with that level of sound perception referred to in the first paragraph would like to take a trip to my humble abode to assist me.............

I'm now running Isoacoustic Mini's under the DS and the Exactbox and, for the hell of it, stuck all 6 amplifiers on Gunstig pads..................

Regards

Richard
 
I have to admit Richard I'd love to hear how your set up compares to my lil ole Tunebox Keltik setup. I have to say I've always had success with getting a sound I love quite easily with my kit, I don't find it too fussy.
Sometimes when we stray from the path so much especially with massive investment it's difficult to be objective. Maybe another pair of ears would be just what is needed.
David
 
I don't find it too fussy.

David,

I don't find mine that 'fussy' either. I don't necessarily want to be seen as challenging what is an 'established mantra' so as I'm happy with what I'm hearing 'as is' as I said above somewhere - 'if it ain't broke don't fix it'. Tune Dem'ing is, obviously performed in a room before any SO type treatment, so the room is going to influence you trying to determine the 'sweet spot'. It's almost the chicken and egg dilemma.

What I do know is that even at this interim stage the Exactbox does things the SNAXO doesn't.

The downside of all of this though is that the system becomes even more revealing of the source material. Khmer by Molvær is oft quoted with reference to its bass bits (amongst other virtues of that album), it doesn't even get that close to other tracks with 'real' bass e.g. Djuma Soundsystem or Trentemøller (not that I'm a particular fan of these but as tracks to find out what is happening in 'sub-woofer' territory they simply can't be beaten).

You are welcome to come by and have a listen if you're up this way........

Regards

Richard
 
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Have you acoustically measured with REW?
You can also try REW’s ‘room simulation’ feature, simply enter your room’s dimensions and virtually move your speakers and listening position, you are looking for the flattest ( less wiggly) response.
Keith
 
I find the waterfall plot most useful, it’s not always about getting the flattest response, but the one that excites the room least.
 


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