The new budget speaker king?

Zilch · Jan 29, 2008

More Data:

Woofer parameters, measured, one sample:

Re = 7.16 Ohms
Fs = 67.31 Hz
Qes = 0.71
Qms = 2.4
Qts = 0.55
Le = 0.59 mH

Box tuning Fb = 73.76 Hz (as Fm).

Surprisingly, the box is well sealed; I tested with stethoscope and 30 Hz sine tone. Turns out that both drivers have sealing gaskets attached.

Tweeter and woofer impedance curves, below.

Zmod crossover:

Parts list:

L1 = 255-250 Inductor, 18ga, 1.0 mH, $7.67
L2 = 255-036 Inductor, 20 ga, 0.5 mH, $3.88
C1 = 027-560 Capacitor, MPP, 6.8 uF, $4.37
C2 = 027-552 Capacitor, MPP, 4.7 uF, $3.67
R1 = 004-3 Resistor, NI, 3 Ohms, $1.25
R2 = 004-20 Resistor, NI, 20 Ohms, $1.25

Total per speaker using Solen caps = $22.09
Using Dayton caps = $18.71

The 1" black fiberglass insulation is used by sheet metal fabricators for damping HVAC plenums. I have specs on it somewhere. It's convenient because it has a glueable backing, and I use it routinely for minis. I paid $5 for a 4' x 6' sheet yesterday, and used about $0.25 worth.

1.5" port plugs were $2.69 apiece in my local gourmet ACE Hardware plumbing department.

When Ray gets back, y'all might convince him to sweeten this. There remains a bit of rising response in the woofer, which could be flattened with an additional step compensation or broadband notch filter, bringing up the LF response a couple of dB.... :thmbsp:

Edit: Added off-axis response with bonus 1/4" nearfield low-frequency measurement. The port is plugged.

Finally, the tweeter actually playing as one doesn't much like the stock grilles @ 5kHz. Leave them off if you can hear that on-axis notch, or make new ones without the tracery in the tweeter region.

O.K., I'm really, really done now....

:

archie2 · Jan 29, 2008

Nice job Zilch. And thanks for all that info. and work. Suddenly my bargain $15.00 speakers may cost $55.00 minimum. :scratch2: Is it worth it? No. But I may do a partial Zilch mod. Haven't decided which part yet. I pulled out an old pair of Pioneer Centrex speakers I was going to chuck just for comparison. They are about twice the size of the Presidians. The Centrex"s win hands down. The biggest attraction to the Presidians is their sound stage, that might be worth preserving.
Thanks again Zilch.

Zilch · Jan 30, 2008

archie2 said:
I may do a partial Zilch mod. Haven't decided which part yet.

Shut that woofer up in the VHF, perhaps with just a lowpass inductor on it in addition to your cap on the tweeter, i.e., single-pole.... :dunno:

80sKid · Jan 30, 2008

I'd be very curious as to how the freq resp would be affected (in an presididan without xover mods) by stuffing the cabinet with lots of polyfil/fiberfil/holofil. Would that tame the cabinet and high freq of the woofer for less money. Obviously it wouldn't be as effective. But would it be at least effective enough to be a poorman's tweak for this speaker?

Are there even cheaper crossover parts than the Daytons? Would they be really awful or just a notch below in sound quality?

Zilch · Jan 30, 2008

You'll not dampen the woofer's HF response with stuffing. It's coming from the cone, dome, and/or surround. Adding the initial insulation made no difference in the HF response; it's not spurious resonances or reflections, rather, is intentional in the design.

There are cheaper capacitors, but non-polar electrolytics such as were used in the originals are an unacceptable compromise, in my view.

Getting the inductor cost down is tough short of winding one's own, which can certainly be done.

These sold for $40, from which perspective it's really a $15 upgrade.

[Running Tang Band 28-847SD Neodymium tweeters in them now, and looking for my kick-ass JBL 115H-1 woofers....

: ]

archie2 · Jan 30, 2008

Zilch said:
Shut that woofer up in the VHF, perhaps with just a lowpass inductor on it in addition to your cap on the tweeter, i.e., single-pole....

That's what I was thinking of doing. I've ordered 3.3uF caps and will scrounge around for the inductor, perhaps brace the box as well although I did note you said it was tight.

x_25 · Jan 30, 2008

Thanks Zilch, I will have to look into these (although I already ordered the 3uf caps, oh well)

Zilch said:
Getting the inductor cost down is tough short of winding one's own, which can certainly be done.

Can you point me in a direction where I could find how to do this? I am not beyond spending an hour or two winding wire to save a couple bucks.

archie2 · Jan 30, 2008

x_25 said:
Thanks Zilch, I will have to look into these (although I already ordered the 3uf caps, oh well)

Can you point me in a direction where I could find how to do this? I am not beyond spending an hour or two winding wire to save a couple bucks.

http://www.colomar.com/Shavano/inductor_info.html
A 1 mH choke needs around 23M of wire at 1.00mm diameter. Try your local automotive supplier and ask them to cut some off their large spool for you. Or try Radio Shack. You can wind around small diameter plastic pipe.

x_25 · Jan 30, 2008

archie2 said:
http://www.colomar.com/Shavano/inductor_info.html
A 1 mH choke needs around 23M of wire at 1.00mm diameter. Try your local automotive supplier and ask them to cut some off their large spool for you. Or try Radio Shack. You can wind around small diameter plastic pipe.

Very cool. Thanks. Now the wire looks like bare copper but I am assuming it is actually insulated?

archie2 · Jan 30, 2008

x_25 said:
Very cool. Thanks. Now the wire looks like bare copper but I am assuming it is actually insulated?

It is enamel insulated. Do NOT use plastic insulated wire as the plastic will probably melt if the inductor heats up enough. I think you can use magnet wire. Look up Wheeler's formula for inductor values. If you have an old inductor lying around and can figure out the wire gage you might be able to reuse the wire with the correct number of turns as an air core inductor.

x_25 · Jan 30, 2008

archie2 said:
It is enamel insulated. Do NOT use plastic insulated wire as the plastic will probably melt if the inductor heats up enough. I think you can use magnet wire. Look up Wheeler's formula for inductor values. If you have an old inductor lying around and can figure out the wire gage you might be able to reuse the wire with the correct number of turns as an air core inductor.

Yeah, that is what I thought. I will have to go see if we have any in the garage (never know what you will find in there). I will have to look around and see if I have any old inductors around, I know I have some but I don't think I have any with that much wire in them.

Zilch · Jan 31, 2008

Heh, heh:

x_25 · Jan 31, 2008

Zilch said:
Heh, heh:

Over kill much?

My crossover caps just arrived so I will put those in later today and report back.

Robie · Jan 31, 2008

x_25 said:
Over kill much?

My crossover caps just arrived so I will put those in later today and report back.

X25, are you going to try them with the 3uF caps first? My 3uF caps arrived several days ago.

If I understand what Zilch has done, he's tweaked these pretty well. To replicate his efforts, we need to order different cap values and inductors for both the woofer and tweeter and perhaps a different tweeter entirely (Tang Band). He may also have dampened the cabinets with insulation and perhaps added a brace?

Sorry I'm slow on the uptake and thanks for a "dumbed down" explanation X25 or whomever.

Zilch, it has been very interesting to see how you approached the tweak. Changing a variable and then testing. Very methodical and confidence inspiring. Thanks.

Zilch · Jan 31, 2008

Robie said:
If I understand what Zilch has done, he's tweaked these pretty well. To replicate his efforts, we need to order different cap values and inductors for both the woofer and tweeter and perhaps a different tweeter entirely (Tang Band). He may also have dampened the cabinets with insulation and perhaps added a brace?

Yes, all but the brace. Not much room in there.

Somebody suggested these were MDF cabs; seems more like particle board to me.

Tang Band worked nicely with the same crossover, measured with the Presidian woofer, below. It sounds better, but doesn't have as good off-axis response as the original.

I had to enlarge the tweeter hole to fit that particular Tang Band in. Looks like there's similar smaller and cheaper ones in the PE catalog. At 4 kHz, I may be running the stock Presidian tweeter on the lower edge of its useful range.

When I threw the JBL woofer in there, I got 15 Hz lower bass. I think I found an even better JBL choice than 115H-1, which I'll try this weekend. They're sounding like credible speakers now, but there's nothing Presidian left except the boxes.... :dunno:

archie2 · Jan 31, 2008

"but there's nothing Presidian left except the boxes."

And with that, the new budget speaker king is dethroned.
It was a nice exercise but in the end, you get what you pay for.

Zilch · Jan 31, 2008

Well, the grilles still fit, too.

:

Same happened by others with Insignias; I've seen three or four of them, as I recall.

All of these endeavors afford insight into speaker design compromises as well as options for upgrade, and thus are worthwhile in my view.... :yes:

x_25 · Jan 31, 2008

Robie said:
X25, are you going to try them with the 3uF caps first? My 3uF caps arrived several days ago.

Yep, gonna throw the 3uf caps in there. Then when I get my hands on some wire I am going to wind some inductors. These are really just rear channel speakers for me so I just want to get a bit more highs out of them and then just leave them be. They are there until I find something better to replace them with (that is in my price range).

farr out · Jan 31, 2008

I had fun farting around with these speakers, but in the end they'll probably end up in the garage in the summer doing Cub game duty while I change the oil in my car for 4 hours :banana:

In the end, not a bad investment on my part, as I found it was really easy to change a cap in the x-over and make crappy speaks sound less crappy. But for critical listening I'll stick with my ESM-3's just as soon as I get the new surrounds and get them on.

archie2 · Feb 1, 2008

Zilch said:
Well, the grilles still fit, too. :

Same happened by others with Insignias; I've seen three or four of them, as I recall.

All of these endeavors afford insight into speaker design compromises as well as options for upgrade, and thus are worthwhile in my view.... :yes:

Very true, a nice worthwhile exercise but still, no longer budget speakers. Not even close.:ntwrthy:
Enjoyed your posts on this one Zilch. I learned something.

The new budget speaker king?

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