Minimus 7 Loudspeakers - Measurements
- Thread starter Zilch
- Start date
skywave-rider
Slumming in Akihabara
skywave-rider
Slumming in Akihabara
Datasheet says the response issues are similar:
http://www.jblpro.com/pub/install/control/ctrl1.pdf
Even though they're starting out with a more sophisticated crossover:
http://www.jblproservice.com/pdf/Control Series/Control 1WH.pdf
[Obviously in need of major Zilchification, they are....
]
http://www.jblpro.com/pub/install/control/ctrl1.pdf
Even though they're starting out with a more sophisticated crossover:
http://www.jblproservice.com/pdf/Control Series/Control 1WH.pdf
[Obviously in need of major Zilchification, they are....
]
skywave-rider
Slumming in Akihabara
SK3 looks to be a woofer protection lamp?
Am I reading the schematic right...are they trying to coax more upper response from the woofer?
Sorry, OT.
Am I reading the schematic right...are they trying to coax more upper response from the woofer?
Sorry, OT.
Seems odd, but yes. The tweeter doesn't need it, apparently.
It's a low-Q (-6 dB) parallel notch filter @ 2.5 kHz.
We'd have to see the native response of the woofer to get why. Either the woofer is rolling off naturally there and it's a resonance peak they want to clean up, or they're running it full-range, essentially, doing the same.
They were $30 apiece in lots of 6 in the JBL Pro Tent Sale.... :thmbsp:
skywave-rider
Slumming in Akihabara
The C1s are probably worth a try for the low end alone, if they can be fixed.
ZM7s rule Lilliput.
ZM7s rule Lilliput.
skywave-rider
Slumming in Akihabara
I had to review this in Dickason (p. 185.):stupid:
So the RLC filter uses the low pass coil.
Dickason says the inductor DCR is significant in the actual depth of the notch, so I assume the lamp's resistance figures into this a great deal.
I should open it up b4 I give it back.
I don't know what the lamp DCR actually is when not lit, but it's liable to be small.
That's how it's operative for protection; current goes up, the filament heats up or illuminates, and the resistance goes high.
Tent Sale is closed for remodel now, but I'll inquire if we can still get the "deal...." :thmbsp:
Stereo now:
I've completed modding the second unit, and it's clear that flattening the response and mitigating the high-frequency excesses of the stock Minimus 7 has allowed what bass they produce to balance the overall response nicely; these are eminently listenable minis now. :thmbsp:
In the course of completing the second one, I learned the following:
1) It's not necessary to remove any but the yellow woofer (+) wire to complete the mod. The other driver connections remain at the stock locations.
2) Nor is it necessary to desolder all of the terminals, so long as the lower hole in each is exposed.
Here's the layout and wiring diagram I made while doing this one:
Notes:
http://audiokarma.org/forums/attachment.php?attachmentid=132322&d=1233206613
http://audiokarma.org/forums/attachment.php?attachmentid=132323&d=1233206613
a) A cable tie secures the 3-Ohm resistor to the stock aircore inductor.
b) A short piece of wire (blue) connects IN (-) to the junction of the 40-Ohm resistor and 4.7 uF capacitor, lower right.
c) All other connections are made using the respective component leads.
d) The large inductor lead and tweeter wires dress neatly through the center of the stock aircore.
e) A #4 solder lug installs on the existing plastic boss, upper right.
f) Drill the rear panel to mount the large inductor between the two bosses on the inside centerline using #4 machine screws from the outside.
g) Double-stick foam tape secures the two caps and bottom two resistors to the stock input terminal plate/cup. Epoxy and other glues are suitable alternates.
I've completed modding the second unit, and it's clear that flattening the response and mitigating the high-frequency excesses of the stock Minimus 7 has allowed what bass they produce to balance the overall response nicely; these are eminently listenable minis now. :thmbsp:
In the course of completing the second one, I learned the following:
1) It's not necessary to remove any but the yellow woofer (+) wire to complete the mod. The other driver connections remain at the stock locations.
2) Nor is it necessary to desolder all of the terminals, so long as the lower hole in each is exposed.
Here's the layout and wiring diagram I made while doing this one:
Notes:
http://audiokarma.org/forums/attachment.php?attachmentid=132322&d=1233206613
http://audiokarma.org/forums/attachment.php?attachmentid=132323&d=1233206613
a) A cable tie secures the 3-Ohm resistor to the stock aircore inductor.
b) A short piece of wire (blue) connects IN (-) to the junction of the 40-Ohm resistor and 4.7 uF capacitor, lower right.
c) All other connections are made using the respective component leads.
d) The large inductor lead and tweeter wires dress neatly through the center of the stock aircore.
e) A #4 solder lug installs on the existing plastic boss, upper right.
f) Drill the rear panel to mount the large inductor between the two bosses on the inside centerline using #4 machine screws from the outside.
g) Double-stick foam tape secures the two caps and bottom two resistors to the stock input terminal plate/cup. Epoxy and other glues are suitable alternates.
Attachments
The Canton "plus s" pics are gone already.These things look like little m7 ripoffs!
4-OHM. 40-70 WATTS.RANGE 45-30K HZ
maybe we could borrow some knowledge frome these babies?? They could have revised the design or just completely ripped them off, but they look almost identical to m7's
Does anybody have them to upload here?
Edit: Found some, below. That's the 12" "Plus C" sub.
So, there IS a sub. :yes:
Can we see some pics, please?
Attachments
Me, too.
Ain't it the truth- I can hardly afford to turn ON my computer to read this fantastic thread. It's held my interest ever since it started in the thread BEFORE this one.
Brian
skywave-rider
Slumming in Akihabara
Check the grilles on those! Model no.?
40-2039B
One's a little ratty, so they're gonna go JBL Monitor Blue here pretty quick.... :thmbsp:
I've had a few days to listen to these puppies and let me tell you this mod is amazing. Turns good office speakers into great office speakers. You guys have outdone yourself 
tylerdurden
Active Member
I finished my cabinet mod. I posted a discription and a link to photos here--
http://www.audiokarma.org/forums/showthread.php?t=75479&page=14a
I havnt received the parts for the xover that you guys designed here yet. I cant wait to get them and try it out in this larger cabinet. Hey Zilch. Is there anything you can think of that we could tweek that would help the crossover take better advantage of this larger cabinet? It is exactly 2 1/2 times the size of stock. I am concidering building a set that is ported. Thanks you!!
http://www.audiokarma.org/forums/showthread.php?t=75479&page=14a
I havnt received the parts for the xover that you guys designed here yet. I cant wait to get them and try it out in this larger cabinet. Hey Zilch. Is there anything you can think of that we could tweek that would help the crossover take better advantage of this larger cabinet? It is exactly 2 1/2 times the size of stock. I am concidering building a set that is ported. Thanks you!!
Your cabs came out beautifully!
My guess is that the larger box will improve the bass response somewhat, but not control the woofer excursion as well as the original, because the air spring is bigger, and thus more compliant.
Given that they later released a ported version, you may be all right with that, but we'd have to know the woofer T/S parameters and run the box sims to be sure. Others here may have more of an intuitive feel for this from experience than me; I go by the numbers, basically....