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Old 25th November 2013, 09:40 AM   #21
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With a 5" mid/woofer, you won't get get any appreciable bass. Maybe that is what you want but I don't think I would ever be satisfied with anything that won't go a bit loud when you might like it.

My first build was a project speaker in a now defunct Australian electronics hobby magazine; a tow way with 8" and 1" Vifa's, now both obsolete. While I liked them, it wasn't until I made one active that I found something much better. When I converted them to three way actives, I found a really good system.

With many good drivers around, together with DSP such as the miniDSP and class D amps, a reasonably low cost and good set of speakers is not all that difficult to achieve, even for a first time builder, more so with an engineering background.

Abs (listening to Harry Manx right now)
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Old 25th November 2013, 10:02 AM   #22
sreten is offline sreten  United Kingdom
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Quote:
Originally Posted by jReave View Post
My mistake - I forgot to calculate for 2 speakers. Doh.

Also hadn't heard about 2m=farfield SPL's before. That's helpful. Thanks sreten.
http://www.pispeakers.com/ssdm_99.pdf

Hi,

The above is a good read if your into that sort of thing.
Also covers the effect of directivity on near / far field.

rgds, sreten.
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Old 25th November 2013, 10:57 AM   #23
sreten is offline sreten  United Kingdom
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Hi,

FWIW whilst I can see the appeal of the ZD5 I'd say you'd
need some experience to know that they are the right
speakers for you. And whilst it has the best drivers at
reasonable cost Zaph had measured at the time, some
drivers do approach the Scanspeaks at lower cost.

In terms of a speaker design the ZD5 is a bit extreme,
rather than a consummate all rounder. Like I said
earlier using a 11L Vas driver in 14L for sealed and
25L vented is not ideal, your accepting compromise
just to use that little extra the 5" driver provides.

However pretty much, a good 6.5" driver is a better
choice that a 5" for an all round speaker, and far
more suitable for an up to 30L tall thin floorstander.

Note that PC's line of Totem clones started off with
the VIC-20, which used a Scanspeak 8545K and
in the TRS-80 design he basically suggests that
it really doesn't provide the extra performance to
justify its extra cost compared to other options.

The Amiga is high value. TBH at extra cost
I really like the look of the ZX Spectrum :
https://sites.google.com/site/undefinition/zx-spectrum

YMMV but I think its a less compromised design than
the ZD5 and a better allrounder. One thing for sure IMO
is it has what I would call a nice bass alignment, tight
and deep, with a room friendly rounded bass roll-off.

However the general idea of a planar tweeter really has to
appeal a lot as the Neo 3 is not a very high value tweeter.

Zaph|Audio

rgds, sreten.
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Last edited by sreten; 25th November 2013 at 11:05 AM.
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Old 25th November 2013, 08:48 PM   #24
tvrgeek is offline tvrgeek  United States
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It really worries me all these pretty expensive kits have square corner boxes. The difference with all 12 edges rounded is dramatic. Of course, that is something a new builder needs to test for themselves!
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Old 25th November 2013, 08:59 PM   #25
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Funny - the biggest thing concerning me if I decide to build the ZD5s - how to get a decent finish on those rounded corners.
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Old 25th November 2013, 11:09 PM   #26
sreten is offline sreten  United Kingdom
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Hi,

Rounding the corners can be applied to any design, and
really often only the three, front sides and top matter.

rgds, sreten.
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Old 26th November 2013, 12:08 AM   #27
qingcai is offline qingcai  United States
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very interesting , could you please list your cross over parametres?
watt of the resisters, and awg of the inductors.
thanks.
Quote:
Originally Posted by CHELMON01 View Post
Hello,

I am building a similar design (same drivers) but from Troels Gravesen, called Ellam XT.

Ellam-XT

Maybe you could check these. Crossover is simpler. Use cheaper component for the filter, Troels usually use usually very expensive components.

As a first project, I would recommand something cheaper.

For instance in french forums (HCFR) you have a few hitmaker which maybe are not discussed here :

DA990 (Peerless SDS134+Vifa DX25) :

Click the image to open in full size.

Enceinte 2 voies haute-fidélité | alexaudio

I have made one of these. Cost +/-130€ (110£)

There is also a floor standing version of these (crossover is different):

Gavroche :

Click the image to open in full size.

Gavroche DX - Just DIY It !

Another project which have much success is Prima (Scanspeak 18w4434+D2608 91300) cost +/- 280€ (230£):

Click the image to open in full size.

Prima - Just DIY It !

You can adress your questions to the designers of these, they speak English. Troels Gravesen also answer Emails.

For DA990 and Prima, there is a French site which folow the kits and they can also do it for you :
speaker-kits wil audio - WilAudio

I also do my shopping there or at Europe-audio (NL).
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Old 26th November 2013, 07:04 AM   #28
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Quote:
Originally Posted by IanT1967 View Post
Funny - the biggest thing concerning me if I decide to build the ZD5s - how to get a decent finish on those rounded corners.
No hope. If you make rounded corners, you must paint them. Veneering round cornesr is beyond our skill as far as you have to use the same sheet to cover side and faceplate.

That is also why you should consider a "cheap" design. You have to learn a bit before doing a 800€ design. You must learn to work with the rooter. Maybe you will have to make the equipment to make circles with the rooter yourself. After that, you will have to learn to have a descent finish just with paint. And if you want you can give veneering a try.

The little design I gave you "DA990" is really very clever and was developped by a professionnal (Recital Audio who sells speaker from 5000€ to 20000€.



Quote:
Originally Posted by qingcai
very interesting , could you please list your cross over parametres?
watt of the resisters, and awg of the inductors.
thanks.
You mean for the Ellam XT device from Troels Gravesen?

Everything is listed there.

I just ordered ordinary capacitors poly there are no big values there.

For coils, the important one is the 1.2mH. I used non ferite cored 1 mm (3$) but you could try a air core 1.6mm (20$).

The tricky one is the 3 mH which could be expensive. But for this usage anything can do. You just have to be sure that the internal resister of coils+ the serial resister give a total of 9.2 ohms. I took a cored one 0.63mm + 8.2 ohm serial resister (nothing more is needed there.)

Interesting thing also for this design is that you can upgrade to a 3 way with the same drivers :

Ellam-FLEX-3W


For DA990 and Prima designs, refer to the BOM of Wilaudio.com (the site works also in English), BOM there were approved by designers.
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Old 26th November 2013, 08:46 AM   #29
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Quote:
The little design I gave you "DA990" is really very clever and was developped by a professionnal (Recital Audio who sells speaker from 5000€ to 20000€.
I wouldn't build a speaker with a crossover at 990Hz that's using a conventional tweeter. The DX25 can sustain a 2KHz LR4 crossover but not a full octave lower without limiting SPL or increasing distortion. See here: Zaph|Audio

The reasoning that the designer put for the crossover point is ridiculous (my rough translation): between 500Hz and 1KHz the frequency response of the Peerless rise from 83dB to 86.5dB (+3.5dB), and this rise could be a problem for the tonal balance if not taken into account. Unfortunately a conventional crossover is not able to solve this problem <snip>.

Frankly, this is the baffle step effect and can be simply compensated by using an appropriate coil. See for example here: Zaph|Audio specifically the transfer function graph: http://www.zaphaudio.com/audio-speak...erfunction.gif

Ralf
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Old 26th November 2013, 09:15 AM   #30
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This is not my design. I can just say that it work very well and that we have built more than fifty of these and everybody is happy with them. Nobody seems to have burn a tweeter yet.

The cross over point is very low. In the floorstanding device "Gavroche" (other designer), they took the crossover point higher (1800hz) and they seem to keep the same overal quality and tonal balance. Anyway, the limitation of this speaker is the woofer in term of power.

Distorsion seems low and not comming frow the tweeter :

Click the image to open in full size.

The floorstanding device was first developped with the XT25 which is better on the paper but was far less good in real.

I will not discuss further the technical aspects of this speaker. Just say it is a realy good one and we are a lot to say so.
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