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Multi-Way Conventional loudspeakers with crossovers

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Old 17th October 2013, 06:35 PM   #11
tvrgeek is offline tvrgeek  United States
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Amiga: Notice his comments on the VIfa tweeter. Truth be had there. 2K second order electrical is still low for the Vifa's. 3K is more like it. ( My surrounds use the XT25 @ 3K 2nd order with RS150's. Still not quite high enough but I get away with it as surrounds)
Dayton kit: I don't know the woofer so I can't comment. If the crossover was below 2K, I would be skeptical.
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Old 17th October 2013, 07:11 PM   #12
sreten is offline sreten  United Kingdom
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Quote:
Originally Posted by tvrgeek View Post

An elliptic is anything with a Q of much over 1.2 or so. Higher then Chebyshev.
Hi,

No they not. They are defined by the fact the response in
stopband does not monotonically decrease it can rise.

The filter in Zaphs design is 1st order low pass followed
by a notch filter. Electrically it is Elliptical /Cauer, as the
response in the stopband rises above the notch.

Click the image to open in full size.

Electrical transfer functions of Zaph's crossover
Note the BSC and bump in the roll off around 15KHz.

It is used in Zaphs design to approximate 4th order
L/R acoustic around the x/o point and then null the
drivers peak. The acoustic result is quasi 4th L/R*,
away from the x/o point the roll off is not 4th L/R.

Zaphs design is a successful use of of 3rd order
Elliptical filter, and 3rd order is the minimum
order for an Elliptical filter, so quite frankly
you've no idea what you are talking about.

rgds, sreten.

* Slightly assymetrical to control vertical directivity.

It is pretty effective, raw drivers in the box :

Click the image to open in full size.

Adding the crossover (ignore sub 200Hz both graphs) :

Click the image to open in full size.

Impressive stuff with just 3 components on a difficult to use bass/mid.
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Last edited by sreten; 17th October 2013 at 07:37 PM.
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Old 17th October 2013, 07:20 PM   #13
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Quote:
Originally Posted by sreten View Post
Hi,

No they not. They are defined by the fact the response in
stopband does not monotonically decrease it can rise.

rgds, sreten.
it wouldn't matter s long as the stopband attenuation level is exceeded any small ripples aren't a big problem.

lilun
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Old 17th October 2013, 08:36 PM   #14
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Quote:
Originally Posted by tvrgeek View Post
Where's my files? Ah, Invalid file.
OK I will rename them .txt. After download rename correctly as frd and zma
Cool, thanks. Need the acoustic offset and baffle dimensions to play (or you could upload your PSD file).
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Old 18th October 2013, 05:16 PM   #15
sreten is offline sreten  United Kingdom
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Quote:
Originally Posted by lilun View Post
it wouldn't matter s long as the stopband attenuation
level is exceeded any small ripples aren't a big problem.

lilun
Hi,

Whether it matters or not has nothing to with the definition.
Used properly of course it doesn't matter, proper use.

rgds, sreten.
__________________
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When your only tool is a hammer, every problem looks like a nail - Abraham Maslow

Last edited by sreten; 18th October 2013 at 05:20 PM.
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Old 19th October 2013, 12:11 AM   #16
tvrgeek is offline tvrgeek  United States
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OK. lets bet a bit more precise even though it is totally irrelevant to a budget build.
The definition of an elliptical filter is that it has equal ripple in both stop and pass. WIKI has very good discussion if it. You can build one by cascading a Chebychev type one and type two filter, which means you have to have at least fourth order. The Q will be greater than one.

If you build one with caps and coils, you will not get the infinite notch in the stop band. You only see that with "perfect" active crossovers.

The Elliptical has the fastest initial rolloff of any analog filter. But it is still the same slope as all others in the same order. Only the knee is sharper. This does nothing to keep away from breakup modes two octaves higher. The steeper slope is what would help.

Now, back to a budget build. I would not build a baffle the way these were. The side ports preclude the large edge radius I favor and I have concluded offset tweeters are more trouble than they are worth on small baffles. I prefer regular polygon cabinets with rear ports and I like to cut the flange of the tweeters to get them closer to the woofer to improve horizontal off-axis. Things can be gained with irregular shapes, but they are not really relevant at this end of the scale.

Again, It would be great if someone wanted to run with a best under $200, F3 of 60 Hz, under 3/4 cubic foot build-off. I would be very disappointed if the talent on DIY could not better these. I probably could. This was an excersize with the SilverFute, a better than expected for the price cheap woofer. Don't expect more from it.

For every increase in dollar spent, does it allow it to be recovered elsewhere?
So, if you went third order and crept the crossover up to , maybe 1900, yes the tweeter would be happier, but where are you going to recover the cost of extra coils and caps?

Is there a cheaper tweeter that would work better? I seriously doubt it but maybe one for $ 2 bucks less could be found. This is a darn good driver for $20.

Can you find a poly cone that could be crossed higher giving more freedom in a tweeter? Maybe, but I find cheap poly cones sound very lifeless compared to cheap paper. The Silver Flute really has more solid bass than expected in a small-ish box with reasonable distortion. It has pretty darn smooth response in it's usable range. Can you beat it? Please do tell.

Could doping the cone help the breakup allowing a higher crossover at no cost?

Is changing to electro caps enough savings to buy better tweets, or to pay for a notch allowing higher crossover?

Can you save a buck by using one resistor in the pad?

Go forth all ye fine folks and do me better. In the mean time I have some bamboo cabinets to build and some MDF finishing techniques I am trying.
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Old 19th October 2013, 08:54 AM   #17
ODougbo is offline ODougbo  United States
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Oh I don't know, I thought they sounded like the King's Trumpets when I heard them, wish I could have kept them for a few days.

What about the next Dayton up the chain? I'm thinking they have more of the $100 tweeter sound. They supply them with truncated rings.

Have two of everything here, woofers, boxes, tweeters, let me know if there are any suggestions for designs.
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Old 19th October 2013, 11:12 AM   #18
tvrgeek is offline tvrgeek  United States
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OK, now you are going to make me put them in a box with my style of large radius baffle and see if I can tweak the top end a tad more. My budget won't hold up to a set of the Santori drivers just yet, so I'll play here a little. Do note, we have two designs now using the Santori's. Both by very experienced designers. (see the vendor section). It took over a year for them. It is going to take me quite a bit if time just to absorb all the info in the thread. Very good reading. This build was a few days. Budget in both time and cost.

I will mount the drivers on a baffle intended to manage diffraction better.
I will measure acoustic offset. I use an old Old Colony Lab "pulser" for this but it can be done with a PC and Zelscope.
I will provide new 1M plots in a quieter environment with consistent gate times.
I normally would not splice in the LF responce. It is too room sensitive anyway. Maybe I will try. SoundEasy allows doing a Hilbert Transform to generate the phase of a spliced plot. I understand it is a comfort factor for beginners to see something on the bottom end that looks normal rather than the artifacts of a gated MLS plot. It does not matter to crossover design.
I will set a measurement reference level that can be reproduced instead of "about a WATT"
Doping the cone to see if I can get a higher crossover by controlling the breakup is not a beginners technique but it is cheap. I will only include it if I can get stupid-lucky first time out. ( I have one extra woofer) You can trash a lot of speakers learning how, so budget it is not. Mess up only one pair, and you could have bought a much better drivers in the first place! ( like the Seas woven poly cones with no breakup problems, copper pole shunts etc. )
I will do a BOM to set a cost (sale prices and what is in the junk box are cheating) to enforce "do better cheaper"
I will assume any complex cabinet shapes, but if that means CNC work, it has to be included in the price. Anything I can do with a table saw can be done with a hand saw. It is just skill and time. If you want to build a dodecahedran, be my guest. I will build a PB box with a cardboard tube port. for impedance measurements.

I will finish off my cheapskate measurement lab guide. I got distracted building a new bathroom this summer. As LIMP can't do PayPal, I never bothered to buy it and just use my WooferTester for impedance measurements. It is a great tool, but not ultra cheap so it did not follow under cheapskate guide. LIMP does. SoundEasy does everything, but it is not beginners cheap either. Look for the post on the PSD-Lite thread. in a few days.

All the software costs about $25 and building a mic as Sigfried shows is maybe another $10. Maybe I'll even do the postal money order to get the LIMP license. Zelscope is about $12 bucks I think. There is NO EXCUSE not to measure! and simulation software is so cheap, there is no excuse not to model.

Time for coffee and get to working. I will not spend any more money for the next round than the first round cost. So don't expect exotic high order crossovers. IF using electro caps saves enough to go third order or add a notch, that is fair game. Hard line on the cost.

I just found out how I keep losing text on the screen. I am bumping the touch pad with the side of my thumb on my new laptop. It makes the curser bounce around. I use a real mouse, so I am going to cover it up.
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Old 19th October 2013, 11:42 AM   #19
tvrgeek is offline tvrgeek  United States
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Quote:
Originally Posted by ODougbo View Post
Oh I don't know, I thought they sounded like the King's Trumpets when I heard them, wish I could have kept them for a few days.

What about the next Dayton up the chain? I'm thinking they have more of the $100 tweeter sound. They supply them with truncated rings.

Have two of everything here, woofers, boxes, tweeters, let me know if there are any suggestions for designs.
Next Dayton is the same tweeter for $1 more to get a truncated frame. Next REAL step is $54 each vs. $19.45. Clearly out of scope for this game. Thread comments suggest it is a good tweeter. I am a Seas fan at that price.

To tame the top end just a little, Radius the top edge 3/4 inch and add a felt doughnut around the tweeter. You can't do much to the sides. In your room, move all the other speakers away so they don't give as many reflections. Rule of thumb is 1 meter in all directions. Of course, all our thumbs are different.
Maybe change the L-Pad to drop the tweeter a dB. I thought it started to suppress the mids a bit which is why I left it hot. Adding a counour filter is upping the cost. Not allowed unless it is recovered elsewhere.

Tweeter offset/horn loading. Nothing helps a tweeter like efficiency. Carving a horn is not easy. 3/4 roundover if it can line up with the surround having no gap may be an approach. Let me look at that. Of course, it will take some crossover tweaks that could imply cost. After the conventional rear ported box, that would be my next trick. I wasn't going to let that one out, but whatever.
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Old 19th October 2013, 12:49 PM   #20
tvrgeek is offline tvrgeek  United States
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Added up the total parts cost, every little bit, excluding tax and shipping
$280 a pair in painted cabinets. T&S are variables I can't control. Where I live, that is about another $50 total.

A $30 woofer and a $20 tweeter adds up really quick! Nothing here is exotic.
So, we have a baseline.
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