another cunning plan

Dedicated to those large boxes at one end of the room
User avatar
IslandPink
Amstrad Tower of Power
Posts: 10041
Joined: Tue May 29, 2007 7:01 pm
Location: Denbigh, N.Wales

#31 Re: another cunning plan

Post by IslandPink »

Nice when a plan works out.

I hope your pole piece is prolonged forwards, just like in the Seas driver !
"Once you find out ... the Circumstances ; then you can go out"
User avatar
Toppsy
Shed dweller
Posts: 2400
Joined: Mon Jul 23, 2007 12:10 pm
Location: red rose country

#32 Re: another cunning plan

Post by Toppsy »

Nice one Ed,
Shows you haven't lost your touch when it comes to building and designing speakers. Build and finish is up to your usual high standard. Pleased the Fostex tweeters have worked out in the design.
Look forward to hearing these at Owston, should you be taking them.

What would be interesting here is how would the same driver combination and XO compare in sound in a conventional box cabinet of the same internal volume? This would tell just how significant (or not) the triangular shape has on the sound. Any takers?
.
User avatar
ed
retired
Posts: 5384
Joined: Thu Jun 21, 2007 4:01 pm
Location: yorkshire
Contact:

#33 Re: another cunning plan

Post by ed »

the only previous experience with the seas was in a vofo cabinet and I didn't like it at all. Dull, dull and even more dull. Not a very useful comparison because the vofo was 80 odd ltrs. I've had this pair on the shelf for more than 10 years and I remember at the time there were rumours that they only performed when sealed.

This is the major thing I've learned about measuring. Clio is very useful at levelling and finding gaps in the response, but when comparing:
The plot for the seas in a voigt pipe looks very much like the plot in the triangle cabinet but the perceived sound is chalk and cheese. Assuming that the drivers had the same characteristics in each design.

I'm going to pad the fostex down by 3db and see what that sounds like, and maybe bring the fostex in at 6.5k(3uf). whatever, I will leave the seas full range.

As for the finish, I'm truly disappointed, so haven't finished them yet. The micron thick top layer on the veneer restricts choices so I'm not sure what I'm going to do yet. The obvious choice would be veneer..but I'm also thinking rub down and be damned and apply some light mahogany spirit stain to whatever appears. The latter sounds like the avant garde approach and is probably the one I'm favouring at the moment. I'm thinking they might resemble a painted dog.

decisions decision...oh waily.
There's nowhere you can be that isn't where you're meant to be
User avatar
Dave the bass
Amstrad Tower of Power
Posts: 12273
Joined: Tue May 22, 2007 4:36 pm
Location: NW Kent, Darn Sarf innit.

#34 Re: another cunning plan

Post by Dave the bass »

ed wrote: Wed Jun 01, 2022 2:08 pm
seas-fostex.jpg
Phwooooar.

Tri-Shoddy!
"The fat bourgeois and his doppelganger"
User avatar
ed
retired
Posts: 5384
Joined: Thu Jun 21, 2007 4:01 pm
Location: yorkshire
Contact:

#35 Re: another cunning plan

Post by ed »

I spent some time yesterday investigating the "room modes" that I mentioned earlier.
I took the test rig into the garden to run a pseudo anechoic measurement(the sun was shining and the wind had disappeared, and asked the boids nicely to shut up).

anyway too many changes at once...with the speakers mounted 1m above ground and 3uf filter and padded 3db down the room modes disappeared. Result!, but the comparisons are of little value due to the change in environment.

I tested again, in room, but with the speakers raised 1m and there was significant change in the "room mode"...so I've learned something for sure, which I'd previously only guessed at.

onward...need some more poly caps.
There's nowhere you can be that isn't where you're meant to be
User avatar
ed
retired
Posts: 5384
Joined: Thu Jun 21, 2007 4:01 pm
Location: yorkshire
Contact:

#36 Re: another cunning plan

Post by ed »

more shenanigins..
I've now tried 3db padded with 2.47uf and 3uf
and unpadded at 2.47uf and3 uf
I'm not sure there is much more I can do with simple 1st order. On re-calibration the seas comes out at 94db and the fostex at 96 db so not much between them.
for the moment I've settled on 3uf(6.5khz) with no padding, which I'll live with for the next few weeks.
both.jpg
both.jpg (84.86 KiB) Viewed 6933 times
combined.jpg
combined.jpg (79.57 KiB) Viewed 6933 times
Initial feeling is that it's not my finest hour, both cosmetically and audially. A bit lacklustre. It's very difficult assessing box speakers when you're used to large electrostatics.
One thing I'm thinking a lot about at the mo is depth. Some may remember that back in the day I was chasing the acane art of 360 degree surround with stereo speakers. The example I used was Annie Lenox 'hurting time'. There is a thread somewhere. Well, try as I might I didn't discover it in the studio, but I did do a bit more work on depth. Depth is a lot more trixy that just relative spl on different instruments. So much for my recordings, but what about other general releases?

I'm rambling now, but the gist is....some of the speakers I've built have proper depth and some are plain 2d, this one has minimum depth....correlation...I'm chasing it, even though it may be smoke.

I may have a time of just listening to the seas on it's own......

also, there is a definite phase issue between 10 and 12khz.
There's nowhere you can be that isn't where you're meant to be
chris661
Shed dweller
Posts: 2556
Joined: Mon Feb 22, 2010 7:29 am
Location: Sheffield

#37 Re: another cunning plan

Post by chris661 »

Ed,

As far as I can tell, "depth" can be attributed to two things while we're listening:

Ratios of direct-to-reverb sounds in the recording. Jennifer Warnes's cover of Bird on a Wire is a really good example here. Skip to 2.57. Lead vocal is front and centre, but the echoed lines are to the right a little, and have some reverb on them. More distant. There's a stark contrast between the snare drum and toms, too.
Classical recordings can be made or broken by this stuff - the percussion shouldn't sound "close", because that section is so far from the audience. If you want the percussion to be louder in the mix, you'd put a mic or two over there, but make sure that mic is feeding a reverb that closely matches the original room. That way, you can maintain the direct-to-reverb ratios as they should be, while adjusting level.

The rest, I'm afraid, is down to the off-axis response of the speakers, and room acoustics. The combination will tend to result in fixed "everything is close" or "everything is far/reverby". Dipole speakers illuminate a very different set of reflections to monopoles, and typical speakers aren't ideal monopoles, either.


My approach was to recognise that my speakers are quite far away and quite close to the side walls, so I used horns for the mid-high range to make sure they don't illuminate the side walls too much. A direct-radiating speaker would give me more side wall reflections, and a more "spacious" but less "pinpoint" image. It's all compromise.
If I sit closer to my speakers, I end up with the "headphones" sound which some people dislike about horns. Not enough of the room's own sound.


For your build, I'd look at BSC and crossing before that 3kHz peak. You'll lose some voltage sensitivity, but hopefully the tonal accuracy will make up for it.

Chris
User avatar
Scottmoose
Needs to get out more
Posts: 1802
Joined: Sat Sep 08, 2007 11:03 am
Contact:

#38 Re: another cunning plan

Post by Scottmoose »

Unfortunately this can be the issue with crossing high -as wavelengths gets shorter, the frequency / phase response is increasingly affected by offsets.

For whatever it's worth, looking at the response I'd tend to agree with Chris that you might want to look at crossing lower, and if you have a primary on the wideband, up the value a bit to reduce that rising midrange response as that can (can) sometimes affect perceived soundstaging as it swamps out some of the higher harmonic cues. Not invariable, but may be worth a gander. The drivers are good, the box is evidently doing what it's supposed to, so to my mind it's more a question of dialling it in to satisfaction.

One suggestion -takes a couple of minutes & 100% reversible. Try the old $0.99 tweak. Get a bit of BAF or similar, make a tiny ring out of it & wrap around the base of the whizzer between it & the main cone. That can sometimes clean things up by reducing some of the lower level (not always so low either come to think of it) phase-related interactions & cancellations between the main cone & the additional.
'"That'll do," comes the cry of the perfectionist down the ages.' (James May The Reassembler)
Website www.wodendesign.com
Community sites www.frugal-horn.com & www.frugal-phile.com
User avatar
ed
retired
Posts: 5384
Joined: Thu Jun 21, 2007 4:01 pm
Location: yorkshire
Contact:

#39 Re: another cunning plan

Post by ed »

chris661 wrote: Fri Jun 10, 2022 9:40 am Ed,

As far as I can tell, "depth" can be attributed to two things while we're listening:

Ratios of direct-to-reverb sounds in the recording.
thanks Chris, appreciate the thoughts.

from a studio perspective I've got 30+ years of playing with reverb and delay, some successful, but I can't say I've really come out with a hard and fast understanding that allows any procedure....

but I didn't really explain myself..

what I was getting at: I've probably 'designed'/built getting on for 2 dozen speakers, mostly full range. Considering a particular recording some of those speakers have had awesome depth(hairs stand up when you discover it), and some haven't. In my simplistic way I've thought it can only be the driver or the aligment or both. As far as alignment is concerned I have experimented with changing volumes in a given box(because thats easy) but never gone further than that. I think I'm guilty of believing it's above my pay grade and resigning myself to 'can't make a silk purse out of sow's ear', or 'can't polish a turd'

IME in my speakers, talking generally, the Fostex have satisfied me with depth, and the alpair's haven't, nor have the betsy's I've played with.

@Scott
thanks for the input....I can see there might be mileage...but....

given the response of the Seas on it's own, I'm wondering if spending much time on a 2 way is a good return on investment. Considering the seas response above 10k and the little that adding the fostex brings to the party.....might 'simple is best' offer more reward for less work....

mmm

If you are at all intrigued and want to waste an hour of your time you're welcome(as always) to come and listen.
There's nowhere you can be that isn't where you're meant to be
User avatar
IslandPink
Amstrad Tower of Power
Posts: 10041
Joined: Tue May 29, 2007 7:01 pm
Location: Denbigh, N.Wales

#40 Re: another cunning plan

Post by IslandPink »

ed wrote: Fri Jun 10, 2022 9:06 am
also, there is a definite phase issue between 10 and 12khz.
That big drop around 10kHz is probably rotating the phase already by 7 to 8kH. Do you find any lack of top-end detail eg. on cymbals ?
What happens if you flip the phase of the tweeter ?
"Once you find out ... the Circumstances ; then you can go out"
User avatar
ed
retired
Posts: 5384
Joined: Thu Jun 21, 2007 4:01 pm
Location: yorkshire
Contact:

#41 Re: another cunning plan

Post by ed »

curses...I was all set to focus on lissnin...I'd dismantled the test rig....and was homing in on getting a 4uf poly...but falcon inform me that no orders under £12.50...well that's their loss....I will just have to add another 1uf to the current clump(they're £0.75 from the local chap).

I will take the xover down to 5 khz and swap the polarity on the tweeter as soon as....mem sahib says the fence is my priority at the mo...

before I do any of that I've just played my top-end test track....'under African skies'. The top end tizzes and shivers, there is no hint of shish. Further, the cow bell rhythm "bum bum bum te bum" right at the end is loud and clear.
There's nowhere you can be that isn't where you're meant to be
User avatar
Scottmoose
Needs to get out more
Posts: 1802
Joined: Sat Sep 08, 2007 11:03 am
Contact:

#42 Re: another cunning plan

Post by Scottmoose »

I've got a pair of brand-new 4.7uF MKPs sitting on my desk; if they're of any use to you Ed, you're more than welcome to them, they're neither use nor ornament just sitting here. I may have some 3.9uF values in my store, although it'll be Monday before I can get in there (they're closed at the weekends).

I'd love to hear the speakers whenever you've a few minutes to spare. :)
'"That'll do," comes the cry of the perfectionist down the ages.' (James May The Reassembler)
Website www.wodendesign.com
Community sites www.frugal-horn.com & www.frugal-phile.com
User avatar
ed
retired
Posts: 5384
Joined: Thu Jun 21, 2007 4:01 pm
Location: yorkshire
Contact:

#43 Re: another cunning plan

Post by ed »

I spent all afternoon yesterday lissnin. Mostly a classical station I've discovered 'davide of mimic'.
On the orchestral stoff there is depth...fingers crossed it's across the board...recording dependent of course.
They are growing on me, and, as usual, first impressions should be kept to oneself.
I will carry on with the 3uf and no padding to let the full picture sink in.
If you want to give me a ring next week Scott, any day is good so far, after 10 pref when the distractions have gone.

I'm beginning to smile, in spite of the ongoing fence
There's nowhere you can be that isn't where you're meant to be
User avatar
ed
retired
Posts: 5384
Joined: Thu Jun 21, 2007 4:01 pm
Location: yorkshire
Contact:

#44 Re: another cunning plan

Post by ed »

1 month on, much lissnin been done.

I'm very happy with the way these have worked their way into my list of successes.
My neighbour has gone away for a week and I've turned the wick up a couple of times. Way above my normal listening levels. One very obvious discovery is that they get a bit brighter when they are playing hard. Extremely revealing.

also gone back to the F6 which is much more rewarding with these than the class d. With the current front end(raspi+picoreplayer+topping E30) after about 1 hour the volume is noticeably louder. I imagine the temp coefficient of the mosfets. Perhaps time to check the bias after an hour, I haven't checked for about 5 years. I guess F6 is still my goto amp.

next week I have an agenda....to try the padding back in at louder volumes...and to try the 2A3 in place of the F6 at louder volumes, with and without the padding.

Also may try the F2 with only the seas connected.

That will be all my fiddling(tomfoolery) again for the next 10 years.
There's nowhere you can be that isn't where you're meant to be
User avatar
ed
retired
Posts: 5384
Joined: Thu Jun 21, 2007 4:01 pm
Location: yorkshire
Contact:

#45 Re: another cunning plan

Post by ed »

cunning plan update

For the last week I've been listening to the F2 with the fostex out of circuit...They sound revealing, smooth, and the bass is a bit thuddier.
Today I've been listening to the 2a3 with the fostex back in, much brighter and Tina Weymouth's voice suddenly became obvious and seperated on little creatures. I don't remember hearing her voice at all with the F2.

I remember back in the day saying to Steve Cresswell when he was trying to integrate a tweeter with an L-pad, 'it will only end in madness'. I should have taken my own advice. I've now got to try the 2a3 without the fostex because the psychology is rearing it's head and I maybe think the fostex is over the top at the moment....could it need padding down a bit more...or not...aaargggh waily waily
There's nowhere you can be that isn't where you're meant to be
Post Reply