synergy.....Take #7

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It's awesome you guys can do that kind of stuff.

If you ever get bored and are looking for a new one to try....
here's the syn7 dimensions. (90x60 & 1.4" throat)

The straight sided wood horn primary is:
W=838mm
H=497mm
D=405mm

Adding the curved foamboard secondary takes it to:
W=1210mm
H=735mm
D=520mm

Not sure how to describe the curvature in a way you could use ??
Other than all the curvature takes place within the 50mm foamboard thickness. I guesstimated a tractrix like curve...
 
Two factors claimed to create horn distortions are Geddes' Higher Order Modes (HOM, search here) and the various factors in this classic article:
Factors Affecting Sonic Quality of Mid & HF Horns & Waveguides


The "towel mod" or equivalent is perhaps the most basic: the goal is to reduce the reflection and delay back into the horn. Putting a towel cowl around a fancy speaker is not to everyone's taste, but less horrific equivalents may be found :D

That's such a great classic article....every time i've read it, i glean a little more. Thx for pointing me back to it.

I'm not above a towel around the mouth....i literally could give the proverbial 'flying fornication'... as to how a speaker looks....:p
HOW DOES IT SOUND???? ;):D
 
Thanks for asking Rob :)

Yes, i found that putting a thin 1/32" sheet of rubber on all the flare mating surfaces, flare to wood horn, and flare to flare, has taken care of resonances.
I've been getting super transients on various builds for a long time, and they are there in spades on the syn7.
But i've never quite heard the subtleties/beauty in timbre I'm hearing.
So I'm really crazy happy with the syn7 right now.

Also, the last 10pr300 came in a week or so ago, so i finally have been able to do some stereo listening. Center imaging is clearly defined, so they seem to be good and consistent.

But I've already undone stereo and have a bms CD in one, and dcx464 in the other for comparison.

One set of measurements recently was to get sensitivities. (all at 2.83v 1m)
Mid: two 8 ohm 10pr300 in parallel...106.6dB
BMS HF 104.4dB VHF 104.9
B&C HF 106.7dB VHF 105.9 (the wind had picked up for these, they may be a little high)

Since all the coax CD section are 16 ohm and relatively under-driven power wise at 2.83v, it looks like available output will match well when driven harder.
Looking forward to distortion measurements.

About the only thing I don't like is when i added the 1/32" rubber, even that small amount spaced out the flare to flare joints in the corners by a thin 1/8".
I had to put some weather stripping in. Doesn't hurt anything other than looks a little, but just reminds me I'll not try foam flares again.
 
Hi Mark,

Which coax do you like the best - and why?

Thanks!

Best regards
Peter


Thanks for asking Rob :)

Yes, i found that putting a thin 1/32" sheet of rubber on all the flare mating surfaces, flare to wood horn, and flare to flare, has taken care of resonances.
I've been getting super transients on various builds for a long time, and they are there in spades on the syn7.
But i've never quite heard the subtleties/beauty in timbre I'm hearing.
So I'm really crazy happy with the syn7 right now.

Also, the last 10pr300 came in a week or so ago, so i finally have been able to do some stereo listening. Center imaging is clearly defined, so they seem to be good and consistent.

But I've already undone stereo and have a bms CD in one, and dcx464 in the other for comparison.

One set of measurements recently was to get sensitivities. (all at 2.83v 1m)
Mid: two 8 ohm 10pr300 in parallel...106.6dB
BMS HF 104.4dB VHF 104.9
B&C HF 106.7dB VHF 105.9 (the wind had picked up for these, they may be a little high)

Since all the coax CD section are 16 ohm and relatively under-driven power wise at 2.83v, it looks like available output will match well when driven harder.
Looking forward to distortion measurements.

About the only thing I don't like is when i added the 1/32" rubber, even that small amount spaced out the flare to flare joints in the corners by a thin 1/8".
I had to put some weather stripping in. Doesn't hurt anything other than looks a little, but just reminds me I'll not try foam flares again.
 
Cool, It's good to hear when projects on the forum are finished. Are you already planning the next one ? I know I seem to have a constantly increasing list of things I'd like to build 'just to hear how they sound'... :)

Rob.

Haha...yes, i'm dying to come up with the next project..
but i'm having a hard time thinking up anything i believe might be able to sound better...
never been in this situation before...can't say i really like it :( lol
 
Hi Mark,

Which coax do you like the best - and why?

Thanks!

Best regards
Peter

Hi Peter,

i still can't lable one as best yet.
i got the dcx when deep in the throws of synergy explorations, and it's only this month when i finished two of the same synergy build.
Until then, i'd put the bms or the dcx in whatever prototype i was working on and just listen for a week or so, making impressions.
So no real head to head opportunities till recently...

That said, here's how i'd contrast impressions to date...

First, they are very similar sounding..which is a good thing imo !:)

The bms seems to have a little more sparkle in the VHF, but the dcx sometimes sounds a little brighter and clearer.
So I think the dcx's HF section is maybe a little better than the bms, and vice versa for the VHF sections.
This is with flat mag and phase response for both, using the same 500Hz linear phase LR96 dB/oct hp.

I can say though, that i like the bms xover point at 6.3kHz better than the dcx at 3.2kHz.
I keep individual volume controls on all driver sections, controlled by a master volume. Typically just for + 3dB adjustments for track tonality adjustment, and also loudness compensation.
With the bms, i often can just change the HF section's level a bit, since it reaches to 6.3k.
But with the dcx i always have to move both HF and VHF, which is a bit of a problem, because moving VHF down diminishes sparkle still further.
Maybe none of that matter to anybody else though...

It probably should be noted, that the bms gives no latitude in choosing xover freq....very narrow overlap.
Whereas the dcx has a nice wide range.
The dcx weighs 2lbs more and seems to have a much stronger magnet....really grabs tools and bolts haha

Hope that helped..will post further after more listening..apples to apples..side to side.
 
I thought I had remembered you saying ports out of the corners had worked for you. Thanks for replying with your experiences.

And yep, getting the port under the center on the cone, moved freq response up enough I haven't felt the need to reduce volume under the cone.

I'm very interested to see how the new Eminence works, too.
If CDs become better priced and can reach down into the dcx and bms low corner freq range, it seems like we will see a lot more builds skipping the smaller bridging mids.

Did you consider the BMS coaxials and if so what made you go with the B&C ?
 
So based on Mark’s experiences it sounds like either the B&C or the BMS coaxials would be a great choice. There are some enticing reports about the sound quality of the Eminence N314X-8, but I wonder about the crossover point; Eminence are saying 800hz or higher. Crossing at nearer to 500hz appears to make things easier with a MEH . . .

Interested in what others think.
 
I think for home use the eminence can be pushed down to 650 Hz with a steeper XO and that there is little difference in ease between 500 Hz and 650 Hz. Even an 800 Hz XO is not that hard although it may restrict you to 10" woofers plus subs, vs the15's you might use at a lower XO. The XO frequency doesn't really add to the difficulty unless you are using a 1" exit CD that requires an XO above 1 khz.

2-way CDs like Mark uses with such good results are more complex because of the additional XO but they may reward with a better top end. Its hard to say without actually trying both
 
Hi guys,

Yep, the bms or b&c both work great. I've used them interchangeably from 480-650Hz up, albeit with a relatively steep linear phase 96 dB/oct xover.....and at very high SPLs.
But as nc535 says, in a home environment, the eminence might work just fine too. Looking at its factory curve, i'd probably try to design for a 600Hz or higher xover, if using a 24 dB/oct or shallower order.

Don't have much of a clue about the AE Dipole 12, other than one potential issue that jumped out from a quick look.
It's huge x-max....that could be a problem in keeping clearance for the cone not to strike the horn.
I generally route in a ring into the horn for excursion clearance, with a depth at least equal to xmax. So that would take some really thick horn walls.

Or use a ring spacer to block out the driver.
But then that's a problem too, because of the need to minimize volume under the cone to get the high frequency extension needed to reach up to the CD.

Bottom line i guess, is that the driver may work fine, but will take some real engineering.
Because even if the xmax clearance issues are worked out, it's unclear (to me at least) how the necessarily longer port length will work out, or what port area will be needed to support the high displacement.
 
Even if you could get those AE drivers to work in an MEH it seems to me that that would be a waste of their capabilities. In the MEH you'll have no need for their wide bandwidth and huge Xmax. You're better off buying something much cheaper that will work fine in the MEH (and with much less work) and selling the AE drivers.
 
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