J12L w/Piezos: How to add "Bass Only" option

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nola50
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J12L w/Piezos: How to add "Bass Only" option

#1 Post by nola50 »

I'd like the option of running just the 12s without the crossover or piezos.

Should I add a (DPDT?) switch or just a separate jack for "Bass Ony"?

Thanxabunch!

Bruce Weldy
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Re: J12L w/Piezos: How to add "Bass Only" option

#2 Post by Bruce Weldy »

nola50 wrote: Tue Mar 15, 2022 8:08 am I'd like the option of running just the 12s without the crossover or piezos.

Should I add a (DPDT?) switch or just a separate jack for "Bass Ony"?

Thanxabunch!
Since all connections are parallel, you'll have to add a switch to keep the signal from going to the piezos.

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"A system with a few knobs set up by someone who knows what they are doing is always better than one with a lot of knobs set up by someone who doesn't."

tallevan
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Re: J12L w/Piezos: How to add "Bass Only" option

#3 Post by tallevan »

I think you would need a 3PDT switch.
In case you are not familiar with this, it's like three SPDT switches ganged together.

One "switch" would connect/disconnect the +ve line from the jack to high-pass filter.
The other two "switches" would bypass the low-pass filter at the +ve in and +ve out.

You couldn't dedicate a jack to "bass only" unless the jack had a lot of internal switches in it.

The wiring would depend on whether you wish to include the woofer low-pass filter when "turning off" the piezos.
If you want to leave the low pass filter in place, you only need a SPST switch to connect/disconnect the +ve line from the input jack to high-pass filter.

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Tom Smit
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Re: J12L w/Piezos: How to add "Bass Only" option

#4 Post by Tom Smit »

tallevan wrote: Tue Mar 15, 2022 8:27 am I think you would need a 3PDT switch.
In case you are not familiar with this, it's like three SPDT switches ganged together.

One "switch" would connect/disconnect the +ve line from the jack to high-pass filter.
The other two "switches" would bypass the low-pass filter at the +ve in and +ve out.

You couldn't dedicate a jack to "bass only" unless the jack had a lot of internal switches in it.

The wiring would depend on whether you wish to include the woofer low-pass filter when "turning off" the piezos.
If you want to leave the low pass filter in place, you only need a SPST switch to connect/disconnect the +ve line from the input jack to high-pass filter.
A DPDT switch, which operates the tweeters as Half-on/Off/All-on, works well, and gives one options. I have to figure out how to enable macros on my Ubuntu 20.04 in order to see the image that I had saved, of which I wanted to share. I searched in the forum and found the source but it has been removed.
TomS

nola50
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Re: J12L w/Piezos: How to add "Bass Only" option

#5 Post by nola50 »

I have a rough idea to use a DPDT switch. The center would be the signal from the jack. One direction goes to the crossover, the other goes directly to the speaker connection at the crossover output to the woofer.

Does that make sense?

Bruce Weldy
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Re: J12L w/Piezos: How to add "Bass Only" option

#6 Post by Bruce Weldy »

nola50 wrote: Tue Mar 15, 2022 10:40 pm I have a rough idea to use a DPDT switch. The center would be the signal from the jack. One direction goes to the crossover, the other goes directly to the speaker connection at the crossover output to the woofer.

Does that make sense?
I wouldn't do that. Because the speaker is still connected to the crossover too, you are sending the signal back upstream to the crossover even though you aren't using it. Personally, I'd leave the crossover in play all the time and just turn the piezos on and off. The low pass crossover actually enhances the mids - which is a good thing playing without the piezos. I used it in the Jack 15 that I built as a bass cab only.

6 - T39 3012LF
4 - OT12 2512
1 - T24
1 - SLA Pro
2 - XF210


"A system with a few knobs set up by someone who knows what they are doing is always better than one with a lot of knobs set up by someone who doesn't."

tallevan
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Re: J12L w/Piezos: How to add "Bass Only" option

#7 Post by tallevan »

Tom Smit wrote: Tue Mar 15, 2022 9:15 pm
tallevan wrote: Tue Mar 15, 2022 8:27 am I think you would need a 3PDT switch.
In case you are not familiar with this, it's like three SPDT switches ganged together.

One "switch" would connect/disconnect the +ve line from the jack to high-pass filter.
The other two "switches" would bypass the low-pass filter at the +ve in and +ve out.

You couldn't dedicate a jack to "bass only" unless the jack had a lot of internal switches in it.

The wiring would depend on whether you wish to include the woofer low-pass filter when "turning off" the piezos.
If you want to leave the low pass filter in place, you only need a SPST switch to connect/disconnect the +ve line from the input jack to high-pass filter.
A DPDT switch, which operates the tweeters as Half-on/Off/All-on, works well, and gives one options. I have to figure out how to enable macros on my Ubuntu 20.04 in order to see the image that I had saved, of which I wanted to share. I searched in the forum and found the source but it has been removed.
Tom refers to a DPDT on-off-on switch, I think.
As opposed to a common DPDT on-on switch.

That would work great how Tom describes if you want the piezos on/off/half-on AND the low pass filter to remain connected to the woofer.

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Tom Smit
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Re: J12L w/Piezos: How to add "Bass Only" option

#8 Post by Tom Smit »

I have been given a link, and here it is... viewtopic.php?f=14&t=19211
The tweets don't have to exactly half, but instead, have the upper 4 tweets as the half (and the remainder would be off). Then, the other two switch positions would be on, or off.
TomS

tallevan
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Re: J12L w/Piezos: How to add "Bass Only" option

#9 Post by tallevan »

Tom Smit wrote: Wed Mar 16, 2022 9:29 pm I have been given a link, and here it is... viewtopic.php?f=14&t=19211
The tweets don't have to exactly half, but instead, have the upper 4 tweets as the half (and the remainder would be off). Then, the other two switch positions would be on, or off.
That is a good link.

I see that the impedence of the tweeters would double in the half-on position, compared to the full-on position.
Is that not a problem? I suppose the high pass filter doesn't care much about the impedence of the tweeter array.

I also see that in that circuit the high and low pass filters remain in play no matter the position of the switch.
Is it not worth bypassing the filters when the tweeter array is full off?

I understand the low pass fiter remaining on with the tweeter array off might be fine, depending on your tastes.
But the high pass filter? Does it have so little effect on the woofer that leaving it in place makes no difference?

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Bill Fitzmaurice
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Re: J12L w/Piezos: How to add "Bass Only" option

#10 Post by Bill Fitzmaurice »

From the plans:
The low-pass filter on the woofer reduces impedance in the midrange to allow higher current flow, and therefore higher sensitivity from 1kHz to 2kHz... It’s used in all cab configurations, with tweeters or without. The increased output it gives below 2kHz is quite beneficial, while that lost above 2kHz is moot, as the dispersion angle above 2kHz is too narrow to be useful.

nola50
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Re: J12L w/Piezos: How to add "Bass Only" option

#11 Post by nola50 »

As per Bill, I'll turn off the tweeters and let it ride!

Thank you all for the comments. This forum is da bomb!

:hyper:

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