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post #11 of 16 Old 09-10-15, 09:20 PM
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Re: Connect passive sub to 2.0 receiver using plate amp

If you can solder, you have 2 options:
The first option is a passive line-level XO (see attached). This will not yield a perfect response but even a textbook response will be multiplied by than the mains/sub's own rolloff and the room response at these frequencies. Also it is limited to 2nd order. Note that I did not bother to optimize since it needs to be optimized to your preamp's output impedance and power amp's input impedance. I just took typical values of 1k for output and 100k for input. This was done using LTspice (free). The circuit illustrate why you cannot use a 8 Ohms crossover (As Kal mentioned )

The second option is to build an active line-level crossover (like Kal was proposing). This one will have buffers between each stage and yield text book response at the power amp input, so you are free to use a plate amp or PA amp. A good example can be found here at http://sound.westhost.com/project09.htm (a 4th order is also available from there).
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post #12 of 16 Old 09-11-15, 06:57 AM
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Re: Connect passive sub to 2.0 receiver using plate amp

I realize the flow of the thread set me in DIY-mode. You can simply used a MiniDSP b/w pre- and power-amp if you do not want to bother... you GET the EQ as a bonus!
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post #13 of 16 Old 09-11-15, 08:25 AM Thread Starter
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Re: Connect passive sub to 2.0 receiver using plate amp

Ok, thanks again!

I'm not really that hugely experienced in soldering, I do if I need to but try to limit it to 'repairing' my amp by replacing stuff if it's broken. (as I will need to replace my 4050v modules...)

So if I understand it correctly, this

http://www.amazon.com/Hifonics-HFEQ-...rossover+2-way

I could simply put between my pre amp and amp for the sub and the other amp for the normal speakers. it's for cars but I guess a modified laptop power supply would do the trick? If I take an Inuke PA Amp, I have DSP there. Or can I get a crossover with DSP in it?

It would help if you could post some links or the product name of stuff I need. I know I need to have a crossover to do the high/low filtering, it should have 1 input and 2 outputs (or 2 inputs and 2 outputs) but i'm really getting confused

This is why I added below a diagram of what I think based on this information would be the setup. Help in finding the right side (passive sub) would be appreciated. I put all the boxes I need information on in Red.

Thanks!
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post #14 of 16 Old 09-11-15, 12:17 PM Thread Starter
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Re: Connect passive sub to 2.0 receiver using plate amp

actually I think I simply need a minidsp 2x4 and can connect any PA amp of my liking to it to power my subs...maybe I was over complicating things...only downside is that the minidsp is quite expensive, 160 euro.

Is there a cheap(er) alternative to the miniDSP? Except maybe for 'freeDSP', an open source initiative. Pity I live in Europe...

this for example:

http://www.ebay.com/itm/2-Channel-2-...item1c42fa4659

Last edited by bobdebouwer; 09-11-15 at 01:08 PM.
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post #15 of 16 Old 09-11-15, 09:43 PM
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Re: Connect passive sub to 2.0 receiver using plate amp

Quote:
bobdebouwer wrote: View Post
actually I think I simply need a minidsp 2x4 and can connect any PA amp of my liking to it to power my subs...maybe I was over complicating things...only downside is that the minidsp is quite expensive, 160 euro.

Is there a cheap(er) alternative to the miniDSP? Except maybe for 'freeDSP', an open source initiative. Pity I live in Europe...

this for example:

http://www.ebay.com/itm/2-Channel-2-...item1c42fa4659
This seems like what you want in therms of XO but doesn't come with a case at 75CAD. He is using quality op-amps but there is more to it.
The thing you linked on amazon is about 125CAD.
The MiniDSP 2x4 "in a box" is 105USD (see http://www.minidsp.com/products/mini...ox/minidsp-2x4). It has all the XO + EQ/DSP you need and you can switch from one setup to another as the music is playing. It has my vote!
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post #16 of 16 Old 09-12-15, 01:03 AM Thread Starter
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Re: Connect passive sub to 2.0 receiver using plate amp

Yeah, I have to say I totally agree with you!

I was a bit worried to buy a minidsp as I need to pay a lot of customs and VAT etc. when I buy this from hong kong, about 50 EUR extra.
There was a webshop in holland (100km away from me) selling it for 160 EUR (!!), one in germany for 120 (EUR) but strangely enough, I have actually found a French webshop, 'Audiophony.fr' where I can buy it for only 95 EUR! At this price it's an absolute no-brainer.

http://www.audiophonics.fr/fr/appare...ue-p-8270.html

I have been looking the web for a second hand amp, there are plenty of amps for sale which have +/- 500-1000W RMS for +/- 150 euro.

This would mean I can get a 1000W RMS system with the best DSP on the market for only 250 EUR. I can build the passive lilwrecker subwoofer (if I use the cheapest driver) for about 300 EUR which means 550 EUR for a 500W RMS sub extending to 18Hz -3db...
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