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Old 31st January 2006, 08:50 PM   #1
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Default Adding stereo subs - best method of integration.

Hello

I have decided to add stereo subs to my system - nothing too devastating, I'm not after daft SPL or anything like that but after using my HT sub (sealed isobaric using 12s) with my main speakers for a bit, I do prefer the results

However, the HT sub is for HT and isn't usually connected to the main system plus it doesn't do the reproduction any favours IMO - it just isn't a musical sounding sub... Great for explosions and stuff - even dance music at a push but not anything with texture IYSWIM.

So.. Stereo subs seems like the way to go - I can build them but really wanted any thoughts on the best way to integrate them. I don't want a passive system, partly because I don't want to spend the half a million pounds on the components necessary to build a passive 4th order 80Hz crossover... and partly because I'd like to be able to set the cut off frequency based on how they actually sound in the room without swapping out expensive bits and pieces.

I have a choice of a gainclone, a Kenwood KA 5020 or a 60w @ 8 ohms PA amp to run them unless there is a better solution, I have an unused out channel on the preamp so that's all taken care of.

I guess I need an active low pass filter but don't know what's about - I did look for a 2 driver (L+R) plate amp with built in crossover but they all seem to be for a single driver (summed stereo?)

What's out there in terms of a 24db active low pass that I can use? I don't mind building it from a kit but anything paper based is possibly beyond me TBH. I looked at the ESP site and project 9 seems suitable but it's a bare PCB and I'm not experienced enough to work out all the component values and all that.

Is there a plate amp with built in LPF that'll run L+R subs?

I have an active crossover that used to live in the car which did exactly what I would need to do - is it worth experimenting with that or using a similar type of car sub active LPF?

Any ideas welcome
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Old 31st January 2006, 09:17 PM   #2
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You say you've got pre-out from your amp, but do you have power in?

You really want an active crossover to cut the frequencies to your main speakers. This may also improve their performance by releiving them of low end reproduction.

What are you're main speakers?

I'm about to finalise my crossover design (once I've managed to measure my responses) I can send you my spreadsheet to calc 4th order crossover components. I haven't done the linkwitz transform yet but there is a spreadsheet on ESP site. Can you follow a schematic and layout on strip board ?

I might even volunteer to build you a crossover as I'm doing one anyway (and it gives me a chance to try out 2 different crossover frequencies).
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Old 31st January 2006, 09:27 PM   #3
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On the other hand, my opinion is just based on what I'm doing at the moment.

You may be able to match the natural roll-off of your mains with a LP filter on the subs. That's not something I know about.
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Old 31st January 2006, 09:29 PM   #4
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I won't debate on your choice to make stereo subs rather than one good one, but I will say that using gainclones to power them will be no good. In fact probably all of those amp choices aren't really going to cut the mustard for a proper sub.

It would be helpful if you gave details of your main speakers.

As for the filters etc, take a bit of time on the ESP site, it's all there and loads of total beginners have built successful systems from the articles and projects there, and there is a help forum.

Alternatively one of the plate amps from CPC would probably do the whole job.
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Old 1st February 2006, 12:35 AM   #5
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In your situation I'd go for a cheapy pro amp to drive them, and look for a second hand analogue pro crossover to do the lowpass. Maybe use it to do a high pass on your mains too. Other option is to buy 2 plate amps, 1 for each sub.

Good prices for new pro gear here:

http://www.thomann.de/gruppe-PAAP-3....ad94951c8f4101

Though I've never shopped there.


You're kind of limited for drivers here in the UK. Can look at peerless xls from wilmslow or bk electronics, or try the Lab12 from pro audio parts. Can also look at pro drivers though they don't go as deep as 'home subwoofer' type drivers.

http://member.newsguy.com/~stigerik/almighty/

pro based sub.

If you go the esp route I have a fully assembled and working power supply board (p05) with 'wall wart' power supply for sale.

Various FS:esp boards/caps/resistors UK

cheers,

Rob
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Old 1st February 2006, 04:15 AM   #6
muhy3 is offline muhy3  Australia
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If you decide to implement an active crossover I would also add a high-pass filter to reduce excursion below usable frequency, and also just in case you have an XLS like me which seems to go weird when playing records... the high-pass at 17Hz solved all my problems.
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Old 1st February 2006, 07:53 AM   #7
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Thanks everyone

I do have line level inputs on the amps - I'm not sure what you mean by power in TBH.

The main speaker woofers are Seas L22RNX/P in a 60 litre ported box tuned to 26Hz and while the FR is fairly flat to 26Hz, they aren't really giving me what I'm after. Most music sounds OK but kettle drums can sometimes sound a bit anemic compared to when the sub is used.

I'd be interested to see the spreadsheet, cheers jimbo1968. I may be able to follow the diagram if it isn't too complicated. I have only ever built a PSU from a diagram ...

The ESP site does seem a little daunting to a beginner TBH - I don't want to end up with a load of components I can't put together and the soldering iron stuck in the wall Maybe I should bite the bullet and try one of the projects if there isn't anything more suitable (easier to implement)

I'll have a look at CPC plate amps later.

My HT sub runs from the PA amp ATM and works OK but I did wonder if any of the kit I have would be entirely suitable.

Thanks for the links Rob, I'll have a look at them when I get back from work.

Cheers, murhy3, rumble filter added to the ideas list.

Thanks again
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Old 1st February 2006, 05:25 PM   #8
ScottG is offline ScottG  United States
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Quote:
Originally posted by quickshift
Thanks everyone

I do have line level inputs on the amps - I'm not sure what you mean by power in TBH.

The main speaker woofers are Seas L22RNX/P in a 60 litre ported box tuned to 26Hz and while the FR is fairly flat to 26Hz, they aren't really giving me what I'm after. Most music sounds OK but kettle drums can sometimes sound a bit anemic compared to when the sub is used.

I'd be interested to see the spreadsheet, cheers jimbo1968. I may be able to follow the diagram if it isn't too complicated. I have only ever built a PSU from a diagram ...

The ESP site does seem a little daunting to a beginner TBH - I don't want to end up with a load of components I can't put together and the soldering iron stuck in the wall Maybe I should bite the bullet and try one of the projects if there isn't anything more suitable (easier to implement)

I'll have a look at CPC plate amps later.

My HT sub runs from the PA amp ATM and works OK but I did wonder if any of the kit I have would be entirely suitable.

Thanks for the links Rob, I'll have a look at them when I get back from work.

Cheers, murhy3, rumble filter added to the ideas list.

Thanks again

If your speakers extend that low (reasnably flat), then you won't need two subwoofers - just a decent high pass filter and good placement (and you'll still have stereo bass - just attenuated). One of the better placements for a mono sub is directly behind the listener's position - requiring a full variable phase adjustments (i.e. not just a switch). Such a placement provides greater tactil sensation.

See what I posted here:

Most Musical DIY sub?

(as Rob has mentioned, you could use two of these for stereo - but again with proper placement and phase adjustment it isn't neccesary)
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Old 2nd February 2006, 01:01 AM   #9
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Quote:
Originally posted by quickshift
I'd be interested to see the spreadsheet, cheers jimbo1968.
you'll have to allow forum emails, as it can't be uploaded in a message.

The equations and method are from the Filter One manual that you will need to read. Find it here:
http://www.delta-audio.com/Active%20filter%20one.htm
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Old 2nd February 2006, 09:38 AM   #10
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Quote:
Originally posted by jimbo1968


you'll have to allow forum emails, as it can't be uploaded in a message.

The equations and method are from the Filter One manual that you will need to read. Find it here:
http://www.delta-audio.com/Active%20filter%20one.htm
Thanks jimbo1968

I think forum emails are allowed, if not, my email address is m_i_k_e_s_g_7 (at) gmail (dot) com - without the underscores.
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