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Old 31st March 2010, 10:38 AM   #1
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Default Subwoofer to Aleph-X

Hi,
Last year I’ve build Aleph-X based on KK boards, amplifiers runs fantastic. They are driving B&W CM1 speakers…I was thinking of adding a B&W ASW-610 subwoofer connected as is described at the attached picture. I’ve choose this type of connection, because I have a manual volume control on my DIY Aleph P1.7.
I’m interested, should be a problem, and what is the allowed maximum length of the cables???
Thank you at advance,
Toni
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Old 31st March 2010, 11:12 AM   #2
Mfly is offline Mfly  Netherlands
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Should give you no problems at all. The 'high level' input of most subwoofers has such a high impedance it does not notably influence the behaviour of the rest of your system. With a nice cable, length can easily be a couple of meters, probably even 10 meters or more.
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Old 1st April 2010, 09:42 AM   #3
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Hi,

you can´t connect an Aleph-X directly to a subwoofer because:

1.On startup you have a lot of DC on the outputs
2.You would short your -Outputs (it´s a bridged amp remember)

The only practical sollution is to conect the subwoofer to the preamp via an Y-adapter.

William (who had the same problem with his REL woofer)
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Old 1st April 2010, 10:00 AM   #4
Mfly is offline Mfly  Netherlands
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Quote:
Originally Posted by wuffwaff View Post
Hi,

you can´t connect an Aleph-X directly to a subwoofer because:

1.On startup you have a lot of DC on the outputs
2.You would short your -Outputs (it´s a bridged amp remember)

The only practical sollution is to conect the subwoofer to the preamp via an Y-adapter.

William (who had the same problem with his REL woofer)
Sorry, didn't realize that it indeed takes a while for the Aleph's to stabilize.

Point 1 could be solved, but I cannot come up with a very elegant solution at the moment.
Is there a way of taking half the signal referenced to ground to avoid shorting?

Don't shoot me if I'm asking stupid questions :-), quite the noob here.

Last edited by Mfly; 1st April 2010 at 10:05 AM.
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Old 1st April 2010, 10:31 AM   #5
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Thank you Mfly and William,
William just one remark…
1. On startup I have max 200mV witch is going down to around 80-90mV
2. How can I short my outputs….”ground” connection’s on subwoofer are not in contact, they are separate
About third solution….I drive my Aleph-X balanced from Aleph P1.7… So is it possible to feed the subwoofer taking only “+” from XLR connector (from both channels)????
Thank you very much,
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Old 1st April 2010, 03:15 PM   #6
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Hi,

absolute DC (referenced to ground) is much higher than 200mV. Most have around 5-10V on startup.
Are you sure the ground input are not connected? If not, and if they have an input cap you could connect the Aleph-X.
Taking only half the signal is possible but it is quite distorted at high levels.

William
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Old 11th June 2011, 02:04 PM   #7
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Bit late, but thought I'd chime in anyway.
I own an ASW610. I made a nice deal on it. But in retrospect I'd like to have saved up a bit more to buy something really decent. It's an okay sub for the money, but not spectacular. Sure, it can rattle my windows easily, it plays reasonably loud AND deep, and it looks okay. But when I picked it up in the store after paying, I was unpleasantly suprprised: it weighs next to nothing!! It turns out it's made of 100mm fiberboard, not even MDF! And I doubt is't braced internally. The cabinet vibrates quite noticably when the unit is pushed hard. The driver itself seems to be rather light too, which implies a small motor structure.

The resulting sound is nice, when it's not pushed too hard. But you can fairly easily locate where the sub it situated - not just because I know where I set it up I guess that has something to do with added higher harmonics distortion due to the cabinet vibrating. I Use it with Dynaudio audience 122's, the sub filling in everything below 40Hz. The dynaudio's are ported, the ASW610 is sealed. This results in a different sound at and below the x-over region. Not a huge issue, but I keep thinking that it doesn't integrate very well. And that sucks.

When my warranty expires, I'd like to try to see what happens when I build everything into a thick, heavy and well braced MDF of Plywood box, with a separate subframe for the amplifier. Maybe even swap the standard driver for a Peerless XLS10 or similar if it all works well.

Just my €0,02
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Old 11th June 2011, 03:51 PM   #8
qusp is offline qusp  Australia
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Quote:
Originally Posted by tonistefanovski View Post
Thank you Mfly and William,
William just one remark…
1. On startup I have max 200mV witch is going down to around 80-90mV
2. How can I short my outputs….”ground” connection’s on subwoofer are not in contact, they are separate
About third solution….I drive my Aleph-X balanced from Aleph P1.7… So is it possible to feed the subwoofer taking only “+” from XLR connector (from both channels)????
Thank you very much,
I think you misunderstand what hes trying to say. hes saying that since your sub amp is single ended, if you connect the aleph X directly to the sub amp as per your diagram, you will be shorting the Aleph X's inverting output to ground; which is not good. You need to either use only the non-inverting output and ground, or convert the balanced output to single ended before connecting and you will need to use caps, or some other method to remove DC offset. We are talking about absolute DC offset here (across the output and ground), not relative offset across the outputs.
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Old 13th January 2013, 06:12 PM   #9
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Default Subwoofer output for Aleph-X

Hi,

i finally managed to make a subwoofer output for my Aleph-X. Until now I got some signal from my BOSOZ via an y-adapter from one half of the balanced signal. This was fed into a REL 305 subwoofer (low level input)

This signal was 12dB down on the preamp signal causing problems when used with amps having more than 20dB of gain and very efficient speakers. This always kept me switching cables when comparing different amps.

So I came up with a simple solution using a INA134PA fed of the power amps power supply and taking the balanced signal from the amps output.
I've attenuated this by a bit over 6dB so it can follow the amps output until the latter clips. It is now fed into the high level input (100k input impedance) of the subwoofer with different inputs for left and right channels.

Input is 15k, 12k, 2µ2,
regulators 78L18, 79L18 with 470µF-25V caps
one INA134AP and some perf board

My main supply is around 22V, if you have a lower supply voltage the regulators must be changed and you need less attenuation at the input.

Works fine.

William
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File Type: jpg sub-out-2.jpg (34.6 KB, 52 views)
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