Edingdale GT, the ultimate Edingdale? Probably

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izzy wizzy
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#61 Re: Edingdale GT, the ultimate Edingdale? Probably

Post by izzy wizzy »

How is that very ordinary ali box in any way related to that beautiful creation after it? Doesn't seem possible. Great work! Or shoddy, depending on your veiwpoint.

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Greg
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#62 Re: Edingdale GT, the ultimate Edingdale? Probably

Post by Greg »

What a difference! Rounded corners look so good. I presume you sleeved it with other wood before veneering?
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#63 Re: Edingdale GT, the ultimate Edingdale? Probably

Post by Toppsy »

Yes Greg, the entire aluminium box was skinned in 4mm plywood glued to the case with impact adhesive. I found it important though to first roughen up the surface of the aluminium to form a 'key' for the glue. Once the ply panels are glued into place and the sanded I used a 3/8" round-over bit in my router to give the box a similar look to the speakers. The whole was then skinned in the oak flexi-veneer.

I like this flexi-veneer as it comes on a 8' x 4' sheet and has a resin impregnated paper backing. This backing prevents any shrinkage or stretching of the veneer when apply water based glues such as aliphatic resin wood glue or white PVA glue which is applied to both the veneer backing and the plywood case. The glue is left to dry and then the veneer is ironed on with a normal domestic iron set to around cotton heat setting. A single coat of acrylic matt varnish does the finishing touch.

Here is a set of 4mm ply panels ready to glue to the bare aluminium chassis: Image
little eddy
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#64 Re: Edingdale GT, the ultimate Edingdale? Probably

Post by little eddy »

Greg wrote: Sat Apr 27, 2019 9:06 pm What a difference! Rounded corners look so good.
Must admit, I liked the look of the Norge speakers in one of the earlier posts.
TD-125/RB250/MC25FL & 'Snail' phono, NAS/SBT with CS4398 DAC, 41MP pre & MoFo Power, still messing with OBs.
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#65 Re: Edingdale GT, the ultimate Edingdale? Probably

Post by Toppsy »

little eddy wrote: Sun Apr 28, 2019 9:09 am
Greg wrote: Sat Apr 27, 2019 9:06 pm What a difference! Rounded corners look so good.
Must admit, I liked the look of the Norge speakers in one of the earlier posts.
Eddy, the problem with those speakers, which are full on elliptical cabinets, is that they are a right pain to make. Unless one has access to professional full workshop manufacturing processes the only way someone like me can make such a speaker is using the trans-lam construction method. This is very wastage on sheet wood and requires access to a flat bed industrial router to machine the individual lamination frames. The resulting speakers are very heavy as a result and also sheet wood (be it ply, mdf or chipboard) is not always exactly to thickness. The laminations only have to be a fraction of a mm undersized or oversized for the finished cabinets to be either up to 12mm (or more) over or under length. I have a set of CAD plans should you wish to make a set the Norge cabinets?

Back to the Edingdale GT'; Yesterday I finished the second of the external XO boxes and they are both now hooked up to the speakers. As expected this has made no difference in the performance or the sound of the speakers. To be honest it is my considered opinion external XO'ers have no acoustic benefits over the XO being installed inside the cabinets, but it was a useful exercise. Others may have a different opinion and are convinced they can hear a definite improvement in sound quality installing the XO external the speakers.

Here are the finished external Xo'ers: Image
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#66 Re: Edingdale GT, the ultimate Edingdale? Probably

Post by Mike H »

Oh my word!

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#67 Re: Edingdale GT, the ultimate Edingdale? Probably

Post by gninnam »

Mike H wrote: Wed May 01, 2019 7:09 pm Oh my word!

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#68 Re: Edingdale GT, the ultimate Edingdale? Probably

Post by Scottmoose »

Not had any audio time for a couple of weeks, but finally (!) managed to get over to Colin's yesterday -and many thanks to both Linn and himself for the hospitality.

Although it wasn't the main purpose of my going over (which was to take some measurements of The Things currently taking shape), I did take the opportunity of making a few final and very belated measurements of the Edingdale GTs. For the sake of (purely historical now) interest, they're attached below.

Frequency responses are at 2m, quasi-anechoic using short sine sweep with individually calibrated measurement microphone. Gating was set at a slightly unforgiving 3ms. Upper plot has limited 1/48octave smoothing applied, so below about 400Hz you can still see the effects of room modes / reflections etc. quite easily. The lower is same data, smoothed 1/6 octave, which is roughly analogous to what the human brain does, so this is closer what is heard in practice. As a quick explanatory note, ignore the absolute levels: for the sake of saving our ears (not a joke: you don't want to listen to a series of short sine sweeps at over 90dB if you can avoid it), these were taken at a lower drive level and I haven't bothered normalising the absolute value to the usual 1m/2.83v conditions as the response itself doesn't change, just the relative level. For reference, the speaker's nominal is 92dB under those 1m/2.83v conditions.

The four nulls you can see in the upper plot is individual floor-bounce cancellation for the midbass units, which average out, when you apply a slightly more 'real world' condition, to a somewhat smoother overall condition than you'd get with a single unit. You see something similar, albeit to a greater extent, with line arrays. Overall, notwithstanding the usual room-effects on the low end which sans lots of room treatment you can't do a whole lot about with a passive loudspeaker, the Edingdale GT is +/- roughly 2.5dB from tuning to 20KHz.

Upper impedance plot is the GT as-is. It's essentially a featherweight load compared to many. Aside from the usual twin vented box peaks, it doesn't vary by more than 3ohms over the audio range, and electrical phase angles are similarly benign.

Lower impedance plot is the GT with the input Zobels added. Which are more or less doing what they are supposed to, making the already easy load even more stable. The upper box peak is essentially flattened (the lower is irrelevant, but also suppressed), and it basically flat-lines across the rest of the range, staying within a +/- 1/2ohm tolerance, with one exception: in the 2-octave zone 400Hz - 1.6KHz, it dips relative to the average by 1ohm. That was the result of me over-specifying the resistance value in one of the Zobels; it's a simple correction by raising the value slightly, no other changes needed. The average works out a touch lower than stock, but being a near-flat-line it should be consistent in its behaviour with a wide range of amplifier output impedances.
Attachments
Edingdale GT.PNG
Edingdale GT.PNG (67.12 KiB) Viewed 6227 times
Edingdale GT stock imp.PNG
Edingdale GT stock imp.PNG (48.59 KiB) Viewed 6227 times
Edingdale GT imp filt.PNG
Edingdale GT imp filt.PNG (41.66 KiB) Viewed 6227 times
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#69 Re: Edingdale GT, the ultimate Edingdale? Probably

Post by Toppsy »

Scottmoose wrote: Mon Aug 29, 2022 3:05 pm
Upper impedance plot is the GT as-is. It's essentially a featherweight load compared to many. Aside from the usual twin vented box peaks, it doesn't vary by more than 3ohms over the audio range, and electrical phase angles are similarly benign.

Lower impedance plot is the GT with the input Zobels added. Which are more or less doing what they are supposed to, making the already easy load even more stable. The upper box peak is essentially flattened (the lower is irrelevant, but also suppressed), and it basically flat-lines across the rest of the range, staying within a +/- 1/2ohm tolerance, with one exception: in the 2-octave zone 400Hz - 1.6KHz, it dips relative to the average by 1ohm. That was the result of me over-specifying the resistance value in one of the Zobels; it's a simple correction by raising the value slightly, no other changes needed. The average works out a touch lower than stock but being a near-flat-line it should be consistent in its behaviour with a wide range of amplifier output impedances.
Last week Scott emailed me the resistor change he mentioned in the above post extract that I have highlighted in bold italic text.
As I am presently unable to proceed further with the Swansong speaker build whilst awaiting delivery of certain items, I decided to checkout my spares box and I found a couple the spec'd replacement resistors - Jantzen Supres 12-ohm 10W jobbies. Saturday last, I swapped these for the original smaller value resistors in the zobel circuit and then sat down for a listen. This has improved the sound and clarity of the upper midrange and was a very worthwhile change. Nice one Scott. :thumbleft:
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#70 Re: Edingdale GT, the ultimate Edingdale? Probably

Post by Scottmoose »

Ha! I thoughts as much. Glad it's worked out well. :) Just got back last night after an unexpectedly extended stay in the north, so should have 1st pass at that Thing filter completed later today if I can get my nose back to the grindstone. ;)
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#71 Re: Edingdale GT, the ultimate Edingdale? Probably

Post by Toppsy »

Just made up a couple the Zobel filters into some cases I have lying around for some time. These are for Alan who has a pair the Edingdale GT speakers and attended the recent Owston meet with his son Craig. Just need to hook them up to my speakers to check all is OK before I post them off.

Image

This has freed me up to breadboard the prototype passive filters for my new speakers, that I'll start this afternoon.
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#72 Re: Edingdale GT, the ultimate Edingdale? Probably

Post by Scottmoose »

You forgot the perspex lid and LEDs to light it all up like Blackpool illuminations. ;)

Nice job.
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