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santa
10-08-2010, 08:07 AM
Hi,
I'm assembling a loudspeaker using the 2445 J as the midrange driver.
I am planning to use an electronic crossover for frequency division.
Upon initial connection to my amplifier I find that the once almost inaudible turn on thump is now alarmingly loud.

I'm considering either adding a capacitor in series with the driver, choosing a value that only attenuates below the crossover frequency of 700 hz or cobbling up a multi pole time delay relay to close the speaker circuits only after the thump has occurred.

What have others done when in my situation?

Thanks!

matsj
10-08-2010, 08:37 AM
Change amp and use a 47uF capacitor as protection.

mats

JBL 4645
10-08-2010, 11:21 AM
In what order are you turning everything ON?

If you turn ON the amps first and other electronics last it will produce a THUMP!

Turn ON electronic devices first and amps ON last! Also power down amps first, followed by the rest of the electronics.

hjames
10-08-2010, 12:42 PM
Hi,
I'm assembling a loudspeaker using the 2445 J as the midrange driver.
I am planning to use an electronic crossover for frequency division.
Upon initial connection to my amplifier I find that the once almost inaudible turn on thump is now alarmingly loud.

I'm considering either adding a capacitor in series with the driver, choosing a value that only attenuates below the crossover frequency of 700 hz or cobbling up a multi pole time delay relay to close the speaker circuits only after the thump has occurred.

What have others done when in my situation?

Thanks!
When I was setting up an Emotiva pre-Processor this spring (since returned), it had a switched 12 volt signal - so I got a Niles Dual AC switch that could be controlled by the processor's trigger voltage to turn my amps on and off ...

See http://www.amazon.com/gp/product/B00086IDDC/ref=oss_product
Seemed like a nice unit, but when I returned the processor , I returned the NILE unit too.


But I generally have my main system driven with a receiver, but I pull its (MAIN) preamp outs to feed a biamp system with 2 large power amps.

I got an Adcom Time Delay unit ... ACE-515 - Top unit in the photo below.
Its got a main power plug that goes in the wall outlet, and a "Sense control" plug that goes in the switched outlet of my receiver.
The reciever is plugged in the wall, the power amps go into switched outlets on the ACE-515. When I turn on the receiver, the ACE-515 see it turn on, and sends power to my
EQ and active crossover first, so they can power up. About 30 seconds later it allows the 2 power amps to power on, so there is no THUMP.

It works in reverse when I power the system down. Power amps go off and their power supply caps slowly empty, about 40 seconds or so later, it turns off the EQ and Crossover.
Again, no thump.

I got mine used for about $60 ... but there are lots of other things out there, I think one of the members here said there are even some kits to do that kind of thing.
47886

richluvsound
10-08-2010, 12:51 PM
Hi ,

I believe Furmann make a product to sync the powering up and down of your components . It has caught my interest .. it retails here around 120 pounds ,so I can only imagine it would be less expensive there in its country of origin... .

I cant find the details at the moment sorry . I know it was used by Widget at the hifi show he recently did .
Perhaps you might PM him for details .

Good luck, uF

santa
10-08-2010, 04:30 PM
I am currently using an Outlaw 990 HT pre/processor and the Outlaw 7125 power amp.
The 990 has a turn on lead that powers the amp up when you power up the processor.

It may be that the processor takes a while to "boot" due to the nature of the circuitry and the amp is coming on line slightly before the pre leading to the thump.

I'll have to investigate further when I have time this weekend.
And I agree, I need better electronics :o:

Thanks for the feedback and suggestions!

1audiohack
10-08-2010, 09:49 PM
If you leave the pre-amp on and cycle the amp off and on, that will tell you if it a sequence thing or the amp.

Sometimes it's a mixed bag, all my D45's transition on and off silently, the D75's bump about 10 seconds after shut down. As a consequence I have sequencers and protection caps where needed.



And I agree, I need better electronics :o:


There's an easy to fix for both issues. Have fun with what you have!

SMKSoundPro
10-09-2010, 12:51 PM
Here is the link. The info is very straight forward.
Scotty.

Link: http://www.audioheritage.org/vbulletin/showthread.php?19613-2445-2380-2405-xover...HELP!&highlight=altec+protection+capacitor

SMKSoundPro
10-09-2010, 12:52 PM
use a 47uF capacitor as protection.

mats

+1000%

BMWCCA
10-10-2010, 10:41 AM
My main system uses DC300A-II and D150A-II and sometimes the turn-on pop scares me! I've twice ordered the Carvin power sequencer and twice had them damaged in shipping (rather stout aluminum front panel corner bent nearly 90. So I gave up. The brief time I had with them showed the panel lamps to be cheap plastic crap but the electronics inside and the sequencing process seemed to function as described at their bargain price.

Carvin AC120S currently on-sale for $149 (http://www.carvinguitars.com/products/single.php?product=AC120S&cid=61)
http://www.carvinguitars.com/images/products/ac120s.jpg47909

BTW: I still intend to move my PS-400 and PS-200 in-place of the D-series to gain the turn-on-delay feature of the PS amps. The occasional turn-off thump is so mild I only find it amusing.

lgvenable
10-10-2010, 02:30 PM
SMKSoundPro
well I'm a pretty good industrial chemist, but with speakers I'll have to admit I'm learning as I go. Even as we speak, I have my mid horns on the front left/right/center mono-tri-amps hooked up to a 2445J-2385 biradial horn. I haven't turned them all on yet, so I haven't heard a thump; but given I'll have 150W/2445J; I'm assuming it could be significant. I was going to do the active cross-overs on my AB Systems at 800HZ for LF>mids.

I'm hooking up a horn based system as I move away from my L100T system which I sold 4 weeks ago.

In the link you posted and this thread, it says alternately to hook up a 47uF cap "in series" and in your link "across the VC". So, asking a dumb question;), > do I place the cap across the inputs or in series with the positive (I'm assuming the conventional red input)??
see the jpeg I posted below> like this?


I'm assuming this digikey supplied -ELNA made cap will work:
604-1054-ND RFS-25V470MG3#5 CAP 47UF 25V ELECT AUDIO RAD

lgvenable
10-10-2010, 06:38 PM
is this the correct way to cap the compression driver in series?
47918

grumpy
10-10-2010, 07:01 PM
If that's an electrolytic, not something I'd recommend
for this purpose, you want to make sure it's non-polar
(not marked with + and - labelled ends), or use two
100uF normal electrolytics wired +\-\-\+ in series
(which gives you a non-polarized 50uF cap ... effectively)
I'd suggest a metallized foil 47uF (Mylar, polypropylene,
whatever ... pick your poison) ... or at least considering
that later.

The diagram is correct though (series connection).

lgvenable
10-10-2010, 07:16 PM
If that's an electrolytic,
yup it is as I have 100 laying around as I recap my BGW amps. What type am I looking for ? I'll acquire some from digikey w/your help.there were like multiple types when I went to their website. alumium (axial) ceramic, etc

It seems I might go ahead and pull the trigger on some 2360A Bi Radials + brackets I turned up to use for my front three channels; so I have time to wait on getting the caps too.;)

lgvenable
10-10-2010, 07:25 PM
I wish when we edit a post we could add a picture or attachment...
anyway like this ehh?

grumpy
10-10-2010, 08:23 PM
Yes, that would work, but might be improved upon
as both I, and Widget in another thread, have suggested.

SMKSoundPro
10-11-2010, 04:25 PM
This is what I used.
http://www.shopping.com/Dayton-DMPC-47-47uF-250V/AKCTZNIN9yp_D4Pd5Aql6g==/info

and as said by others, yes your diagram is correct.

santa
10-21-2010, 05:04 PM
Here is the link. The info is very straight forward.
Scotty.

Link: http://www.audioheritage.org/vbulletin/showthread.php?19613-2445-2380-2405-xover...HELP!&highlight=altec+protection+capacitor

This is just what I needed.
Thank you.

The amp is the source of the problem btw.