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Multi-Way Conventional loudspeakers with crossovers

6.5" 2 Way Monitor Idea
6.5" 2 Way Monitor Idea
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Old 7th December 2017, 11:51 PM   #1
Ugg10 is offline Ugg10  United Kingdom
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Default 6.5" 2 Way Monitor Idea

Some of you may have seen my first thread with some "strange/interesting" ideas on forming nautilus shells from fibreglass for speaker enclosures.

Anyway, having done more research, tried to listen to some very helpful comments and started to understand things a bit more I think I have a half sensible plan that I would welcome thoughts/comments etc. on. Please do RIA !!!

Drivers -

SB Satori MW16P-4 6.5" mid woofer 61/2" SATORI MW16P-4 :: SB Acoustics
SB 29RDC 29mm ring tweeter SB29RDC-C000-4 :: SB Acoustics
(these bust my 150 driver limit but only just)

The Satori has a great reputation for a flatish response, decent bass extension and driving well into the mid range. The Ring tweeter seems to do the opposite, stays flat to over 10khz bit extends below 1khz easily. So they should in theory integrate well.

For enclosure I really like the K&T NADA sealed enclosure, looks simple and stylish, good thick heavy front panel with chamfers and so eminently makable.

But on modelling with BoxSim this enclosure (27.5l Closed), with the drivers, the bass extension was just not there. So did a bit more looking into ports. Finally came across the dbdynamixaudio TL calculators and liked the look of a simple L slot design. I also came across the Focal Trio6 design that has a similar slot and have always liked PMC speakers which again are TL designs.

So, putting the driver data into BoxSim (via FP Graph Tracer), with the same enclosure external dimension as the NADA but with a 20l volume from the TL L Slot calculator I played around withthe port frequency and 35Hz seemed to give a good amount of bass extension but in a very controlled manner.

The aim is to eventually make thee into actives using the NAP200 clone boards plus 500VA toroidal and an active 2 way xover in each. In the mean time I will plan to use my Rotel RB850's in stereo mode with active 2 way xovers. I currently use the Rotels in bridge model with a pair of B&W CBM1SE's so looking for an upgrade on that setup as a benchmark.

As said before - all comments welcome as to whether I am on the right track for a mid size monitor with good bass extension and flat response ?

So here it is in picture format -

Nada Design from Madisound site

Click the image to open in full size.

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TL L slot enclosure dimensions (1.2" slot height, external sizes the same as NADA = 35hz port frequency)

Click the image to open in full size.

Box Sim output - enclose as above, SB 29RDC and MW16P-4 modelled, Xover active 24Db/octave at 2.5Khz (this does not seem to be too sensitive), Activ Xover used to offset to 90db baseline.

Looks nice and flat from 50hz upto 20Khz with a nice bass roll off.

Click the image to open in full size.

Driver data

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Old 8th December 2017, 08:55 AM   #2
Lojzek is offline Lojzek  Croatia
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20 litres vented volume tuned this way is exactly right for the good low end extension. Putting enclosures close to the corners will further reinforce bass and then you can consider stuffing the vents if you find it more to taste.
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Old 8th December 2017, 09:55 AM   #3
Ugg10 is offline Ugg10  United Kingdom
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Lojzek, thanks for the comment, glad I am on the right track The Satori MW16P is a very nice piece of kit and a lot easier to integrate than others I tried (RS180P, SPH-6M, SPH-175HQ). However it is significantly more expensive than these. May have another go with these other drivers again now the box design is pretty close and work with at least one configuration.

Also tried the Vifa XT25TG30 ring tweeter but the SB one seemed to work better and keeps the woofer and tweeter from the same stable.
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Old 8th December 2017, 05:17 PM   #4
Ugg10 is offline Ugg10  United Kingdom
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More searching found this from Arete Audio. 2 Way largish monitor with similar parameters to that which I am looking at. Great bit of work but what really stood out is the use of a Minidsp as active crossover and filter to get an almost flat response from quite a lumpy starting point.

https://areteaudio.files.wordpress.c...al-testing.pdf

So as a half way house for true active (i.e. amp with speaker) I have come up with a Monster Drive box idea (probably nothing new).

Single box with analogue and Digital input, MiniDSP active crossover/filters, Master volume knob and 4 x NAP200 Clones with 500VA 2x 28-0-28 totoidal transformers.
The MiniDSP and MiniDigi cards can have a master volume knob attached, the MiniDigi can have a source switch added (2 x toslink and 2 x spdif) what I have not worked out is whether you can have the MiniDSP analogue input working and/or switchable with the MiniDigi digital inputs. Adda chrome Cast audio and you have a streaming 4x75w class AB poweramp with passive (digital) volume with DSP active crossover feeding the speaker.

Click the image to open in full size.

Adding up the possible costs for this (approx) -

MiniDSP - 100
MiniDigi - 75 (optional as I can use the Chromecast analogue output)
NAP200 clone boards - 40 (x4)
Toroidal transformers - 45 (x2)
Connectors and wires - 40
Case - 50
Total approx 600

Plus looking at around 4-500 for the speakers detailed above (Satori 6.5" + ring tweeter)

So close to 1000 all in.
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Old 8th December 2017, 07:41 PM   #5
Lojzek is offline Lojzek  Croatia
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Whenever I read MiniDSP product features I feel a bit confused in respect how and what is possible to do with it. I think that you ought to be able to do the things the way your schematic depicts. Maybe give some thought if 0.9 Vrms output swing will be enough to drive the output amps as intended.
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Old 8th December 2017, 07:54 PM   #6
Ugg10 is offline Ugg10  United Kingdom
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Thank again for the comments, looking at the balanced version of the minidsp 2x4, this has the option to go balanced or unbalanced depending on the input wire and 2v or 4v output depending on jumpers.

Page 24 https://www.minidsp.com/images/docum...r%20Manual.pdf

I guess as a stop gap I could use the minidsp with my Rotel power amps in stere mode, one for the LF and one for the HF.

Also the minidsp 2x4 HD has the digital input built into the card and is 2/4v output but is more expensive.

Last edited by Ugg10; 8th December 2017 at 07:56 PM.
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Old 10th December 2017, 02:40 PM   #7
Ugg10 is offline Ugg10  United Kingdom
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So, I am officially a pillock !

Revisited the Satori / 29RDC and found that I had traced the Satori incorrectly and when I put it through BoxSim again there was a significant reduction in the bass response i.e. sloped off from about 100hz.

So, revisited my 3 way monitor ideas and have come up with the following -

Dayton RSS210HF 8" woofer in small L slot vented enclosure (17.5l with 10mm slot giving a 25Hz port freq. with fairly heavy stuffing)
TB W4-1337SDF mid driver in own sealed compartment (6.3l but can easily be changed with light stuffing)
SB 21RDC ring tweeter again in own compartment (irrelevant I guess).

Put this through BoxSim and with a H460 x W300 x D350 enclosure and active 24db/octave crossover at 200hz and 2500hz and it gives a pretty flat frequency response with just the odd bobble in the low frequency between 100 and 250 hz.

Looks like a fairly do-able compact monitor with some mid range drivers. Will run either a minidsp or a pair of 3way active crossovers into three stereo amps (got 2 x Rotel RB950 for the mid/high and probably a Behringer A500 for the low).

All comments welcome.

Here's a few pics.

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Click the image to open in full size.

Last edited by Ugg10; 10th December 2017 at 02:51 PM.
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Old 10th December 2017, 03:03 PM   #8
Jim Griffin is offline Jim Griffin  United States
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You should read about Jeff Bagby's Kairos design which use similar Satori drivers. Well received and great sounding.

See the Meniscus Audio writeup on Jeff's design. Read also Jeff's pdf for details at:

Kairos Full Kit (Pair) - Meniscus Audio
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Old 10th December 2017, 04:30 PM   #9
dtaylo3 is offline dtaylo3  United States
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Look at kits on SBA web site.
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Old 10th December 2017, 04:49 PM   #10
Lojzek is offline Lojzek  Croatia
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I am more of an opinion that one should follow one's own instinct while feeling confident enough to produce one of a kind DIY product. The basic requirement of overlapping drivers is met, the XO will be active. Not many unknowns left to deal with. The midrange and tweeter position on a baffle is not optimal for the stereo image projection but that can be remedied by turning the enclosure 90 deg to the left.
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