Midrange advice

[hp1]

I think from memory that the the keltic and kaber mid range xover is not a band pass design ie there is no high pass section to it ,so it will not filter off the low information being fed to the unit .When they say its 118hz they mean that s the the midrange driver /cabinet ie system roll off starting point.
Try adding a 50 mfd non polar cap in series with the mid unit, that will prevent it excursing too much.

 

[S-Man]

If that’s the case, and it does seem likely based on the observations, then it’s a very poor design. It fails on the benefits Linn promote in their literature about going Aktiv.

When I reverse engineered my Ninka active crossovers they were also very simplistic in design.

 

[poppop]

Having just re-read your OP, I wonder if the active XO is doing its job correctly. If the mid-cone is moving that much, it would suggest that the low-pass section of the mid filter is not working (running wide open). Before you invest in a pair of ER15s, try running the Keltiks without the bass amps and see how low they go/sound.

Even when crossed that low, there should not be appreciable movement from the cone. One of my semi-active Ergo has the mid chiming in from 150Hz, and there is no visible movement from them.

The other possibility is a leaky mid-chamber, as David suggested. Running them without the bass amps going, and seeing whether they flap just as much, will narrow down one of the two scenarios.

James
As previous post, Im posting both off to Jez this morning. He says it is something he will check. So, at present I can do the test David suggested. I should have some time on Tuesday to have a fiddle!

 

[poppop]

Guys,
Thanks for all the feedback. Simplistically thought someone would suggest a "heavier duty" job - bung it in - and the games a good un!!
Clearly not that easy, so I will try all suggestions including the different driver suggested by James.
If Im still knocking seven bells out of it - Ill revert to the obvious answer and "Turn it Down a Bit"

 

[david ellwood]

If youre playing it that loud, you are listening from a great distance, or risking damaging your hearing.

Or you already did?

 

[poppop]

David
Yep, I do play certain genres very loud - bands as mentioned + some progressive trance. Im probably about 8m from the keltiks (sitting on Gaia 1's) (the keltiks, not me!) Toed in slightly - after much experimentation. The loudness bug was sorted for a while with a pair of active 15" Tannoy GRF's(?) built by "Speedtsteve" from PF. BUT this is where you will give up on me - they just didnt do it for me compared to the keltiks!!! I know, I must be deaf! Try Boris Brejcha "Angel in the Sky" as he usually features in the mix somewhere, and let me know if your mids pop out their sockets! LoL.

The last time I had my lugs checked was at Specsavers, when I was getting an eye test. Cant remember what they said but I do recall for someone fast approiaching 70 it wasnt too bad.

Steve

 

[poppop]

I indicated upthread that the klimax crossovers were off to Jez, for a "service"
He wondered if any of the speaker builders/designers on PF had any thoughts/comments on the following:

"I have figures that would seem to explain the lack of power handling from the mid unit...

Following figures are voltage gain and not acoustic power output from drive units. 0dB (ie unity gain) occurs at 832Hz and relative to that the output is +3dB @ 200Hz, +6dB @ 108Hz, +3dB @ 90Hz, 0dB @ 81Hz, -3dB @ 72Hz and -6dB @ 62Hz

So loads of output into the bass region going to the mid driver!"

I then of course said I have no idea what you are talking about!

"The figures mean that there is loads of bass going into the mid drivers in essence. Whilst there is more to it than this 0dB basically means flat ie no cut or boost so there is no reduction in what's going to the mid drivers even by 81Hz and it's only -3dB at 72Hz and there's a pretty large boost going on between around 90 and 200Hz maxing out at 108Hz (there's more to it than that and various ifs and buts {such as whether to call the natural gain of the unit x2 and therefore call this 0dB and then reference the other figures to this} but you get the jist I'm sure).

I guess I mean "strange design" more than anything else and one that seems to be just asking for the problems you are having."

Steve

 

[James]

Is the Klimax crossover(s) expressly configured for the Keltiks, or have they been modified? It is highly unusual to push a midrange driver to operate well into the midbass region. The Seas ER15RLY will handle it fine as a midbass driver in its own right, but it'd be getting a hard time at the volumes you seem to listen at. Can the crossover frequencies be adjusted by Jez?

 

[poppop]

James
Yep, the klimax crossover is specifically configured for keltiks.

"As the slopes look like they were meant to be like that and are all present and correct I have no reason to think they are actually faulty."

Ill ask Jez if they can be tweaked - but Im getting the feeling that any change/ "tweaking" may have results that are not ideal!

Cheers.

 

[S-Man]

The ER15 will have less SPL capability if it’s in a sealed box or a smaller than ideal ported box.

I’m not really surprised by this. My Stinkas had similar strange engineering, with +10 dB at 50 Hz provided by the electronic crossover .

I don’t really see the point of putting another mid range unit in with a little bit more X max. It’ll probably only get you another dB or two of extra volume.

If it were me, I would design a passive crossover for the mid to treble and use an active crossover between the mid and bass. However, that’s a very involved job and it certainly won’t sound like a Linn speaker when you’ve finished… Probably a lot better!

An easier route would be to do a digital crossover with mini DSP, or perhaps something like a Behringer digital crossover. You could start with textbook LR4 slopes and probably get results as good as Linn’s. Then add a bit of baffle step compensation to suit the speaker placement.

 

[poppop]

"However, that’s a very involved job and it certainly won’t sound like a Linn speaker when you’ve finished… Probably a lot better!" LoL.

Now come on S-Man, you can surely see from the foregoing that you are talking to an electronic numpty! Even I can see the irrecoverable damage I could cause trying this route.

There was a post a few months back on the Lejonklou forum from someone who had the power supply "serviced" and one or two other bits renewed on his Keltik Klimax and the entire sound of his crossover was transformed! Fingers crossed.

I totally trust Jez to send them back A1. Following that, the inescapable truth - TURN IT DOWN!

Steve

 

[S-Man]

Yes I can see all that.
All the servicing in the world will not solve your “Budgie” issue!

I can’t find it now, but there was a document Linn used to provide which listed the benefits of active. These included lower distortion and increased loudness capability… neither of which are achieved in this design☹ .

 

[Fatmarley]

Agree with S-man. Changing the driver isn't going to help. The quickest and easiest would be to try a passive high-pass filter.

 

[poppop]

FM - Ill talk to Jez about the suggestion.

Last check carried out today (the one that I can do!) - no movement of the midrange cone, in either speaker when giving the bass cone a good shove!

Steve

 

[James]

The ER15 will have less SPL capability if it’s in a sealed box or a smaller than ideal ported box.

I’m not really surprised by this. My Stinkas had similar strange engineering, with +10 dB at 50 Hz provided by the electronic crossover .

I don’t really see the point of putting another mid range unit in with a little bit more X max. It’ll probably only get you another dB or two of extra volume.

If it were me, I would design a passive crossover for the mid to treble and use an active crossover between the mid and bass. However, that’s a very involved job and it certainly won’t sound like a Linn speaker when you’ve finished… Probably a lot better!

An easier route would be to do a digital crossover with mini DSP, or perhaps something like a Behringer digital crossover. You could start with textbook LR4 slopes and probably get results as good as Linn’s. Then add a bit of baffle step compensation to suit the speaker placement.

I recall active Kabers were advertised by Linn to go down to 20Hz, whereas the passive version went down to 45 or 40Hz. I think it was also a 2.5-way design, whereupon both mid-woofers jointly performed bass duties but only the upper one did midrange.

What I'm struggling to understand is why Linn pushed the high-pass section of the Keltik mid filter so far down. The only explanation I can think of is the mid is being relied upon to provide baffle step compensation, when it is the woofer that should be shelved down. I have never seen a pair of Keltiks in the flesh, let alone hear them. But they apparently did not have a very good reception when they were launched. Linn fans much preferred 'Briks.

I agree that a complete (crossover) redesign is the way to go, but probably not entirely helpful for the OP in his situation.

P/S: I've never been comfortable attaching a power amplifier to a naked tweeter. Hence, my last Ergo design (E-X) features a 2-way active crossover to split LF from MF, and a 2-way passive crossover to split MF and HF.

 

[poppop]

All

Thought Id just give a final conclusion to this issue, as many of you had kindly offered help/assistance. I thought it may also be of interest to DIY'ers.
Summary of Jez's comments:

"All done. but one channel has a blown capacitor (literally blown in half! It's been that way for a long time I'll bet) on the mains input for interference suppression. They don't really do much as you can tell from it working perfectly without it but it needs to be all A1 so I'll be having a hunt around for one of the right type tomorrow (A special "Y2" class safety capacitor).

The channels were set a bit differently and the adjuster shafts are a "click fit" which can be moved 90 degree each way and then click into place (ie they can be giving the same response but 90 degrees rotated visually relative to the other unit...so you couldn't go by where the arrow pointed). I've set the second one to match the first frequency response wise and will pull off the adjusters on one and reseat them so the two units match up in terms of where the arrows point on the adjusters. I'll then set them to drop the mids 2dB relative to bass and treble by boosting the bass and treble 2dB... or as close as I can get as they adjust in discrete steps because those are not pots but digital encoders (I cleaned them anyway) which set a binary code to cmos multiplexed analogue switch chips, which then set the level in discrete steps... hmm... I'd have done it old skool if I'd designed it but there you go lol"

So me trying to set gains/frequency on Bass/Treble was not successful(!!) and as suggested upthread, Jez setting the Bass/Treble, meaning the mid is effectively 2dB down, has really helped. The overall sound balance is noticeably better.

The main reason for the crossovers going to Jez, was to have the power supplies serrviced. Hopefully now sorted for another 20 years of action which should see me shuffled off to the great blue yonder! All for the astoundingly fair price of £400!! I cant imagine what the cost would have been if sent to Linn.

Thank you.

Steve

 

[dspatterson]