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Adding a sub to a stereo amplifier


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HI all.

I have a stereo Setup (Denon DRA-375RD and Wharfedale Diamond 9.5) which i am relatively happy with for the time being (with the little one running around).

It is mainly used for music but is also plugged into the TV for when we watch movies. The room is around 20sqm

 

I was thinking of adding a smallish sub to compliment the system using high level inputs as the amp does not have a sub out.

 

What would people recommend for a sub $500 sub, i dont mind purchasing second hand as i will eventually do proper HT when the little one grows up a bit.

 

I would predominantly want it for music but also be able to perform when watching movies (that is more important than sounding good with movies and poor with music)

 

Cheers,

Luke 

 

Edited by thorpef1
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Velodyne, Krix, Focal etc and DIY designs on the net can done as well if you don’t need a certain appearance / pickup some good used subwoofer drivers and plate amp and build box.

 

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Thanks for that guys, i might keep an eye out on the classifieds here.

I was considering DIY, but it looks like it will cost just as much (or more) than buying one second hand- yes i may get better components but its looking to max out the budget of $500.

 

I also assume no issues using the high level inputs to wire it in?

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4 hours ago, thorpef1 said:

I also assume no issues using the high level inputs to wire it in?

Correct - no dramas with your Denon if using this connection method. High-level speaker inputs place an insignificant load on the amplifier (they are very high impedance) and your amp isn't a floating ground design. All good! :)

Edited by pete_mac
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Hi,

 

I’m using a REL T9i through high level inputs on my 2ch system. Works really well. Couldn’t live without it now. I also run my AVR into the .1 input for home theatre use so I’ve got the best of both worlds. 
 

Cheers. 

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8 minutes ago, thorpef1 said:

Thanks Pete.

 

Also, any chance you are the same pete-mac from OzFoz?

 

Yessir!! Ha - I thought your username looked familiar!  :)

Edited by pete_mac
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+1 for the RELs, with only an old Sansui sub for comparison. You can dial it down for music and up for movies. REL actually recommends you wire it up to your normal speaker connections using the Neutrik Speakon cable, so make sure that's included (or budget $80 to buy one).

Edited by David Walker
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On 29/06/2020 at 7:21 AM, thorpef1 said:

Thanks for that guys, i might keep an eye out on the classifieds here.

I was considering DIY, but it looks like it will cost just as much (or more) than buying one second hand- yes i may get better components but its looking to max out the budget of $500.

 

I also assume no issues using the high level inputs to wire it in?

DIY is still worth go such as $213  https://www.altronics.com.au/p/a2451-opus-one-180w-active-subwoofer-amplifier/ and occasional offerings on gumtree like quality Peerless xLs 12 subwoofers and similar for around $150 used, MDF cabinet $70 for materials from Bunnings or even less in gumtree. If you don’t need huge Xmax and earth shattering volumes there are many hifi woofers that give very detailed music performance such old venerable Kef 139 oval woofers, Focal Kevlar 10-12 inch, other Peerless 12 inch, several latest offerings from Dayton, Eton and Scanspeak etc from $50-300 used. Use an online speaker box volume design calculator to size the cabinet like WINISD.

 

Can even try transmission line cabinet designs with very good results if you have space for large cabinet.

Edited by Al.M
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On 29/06/2020 at 5:06 PM, Jhsg said:

Hi,

 

I’m using a REL T9i through high level inputs on my 2ch system. Works really well. Couldn’t live without it now. I also run my AVR into the .1 input for home theatre use so I’ve got the best of both worlds. 
 

Cheers. 

Not every subwoofer can be directly connected to 2 amplifiers at the same time. 

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Thanks guys.

I have set up some alerts for Rel, SVS and also Richter to see what pops up.

 

I have also come across the below busted JBL sub which isnt too far away.

Pending the amp is working fine, what sort of driver would be a good replacement for this amp and box volume (happy to fill the port if a sealed box is more appropraite:

https://www.gumtree.com.au/s-ad/hoxton-park/speakers/jbl-pb12-12-250-watt-down-firing-powered-subwoofer-need-repair-/1247742244 

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16 minutes ago, thorpef1 said:

Thanks guys.

I have set up some alerts for Rel, SVS and also Richter to see what pops up.

 

I have also come across the below busted JBL sub which isnt too far away.

Pending the amp is working fine, what sort of driver would be a good replacement for this amp and box volume (happy to fill the port if a sealed box is more appropraite:

https://www.gumtree.com.au/s-ad/hoxton-park/speakers/jbl-pb12-12-250-watt-down-firing-powered-subwoofer-need-repair-/1247742244 

By the time you ll try to fix it, it might be easier to get that one.

https://www.gumtree.com.au/s-ad/punchbowl/speakers/velodyne-impact-12-subwoofers/1251311942

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1 hour ago, thorpef1 said:

Pending the amp is working fine, what sort of driver would be a good replacement

The amplifier will contain specific EQ for the driver/box it was designed for......   so only the original driver will be a reliable replacement.

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1 hour ago, Irek said:

By the time you ll try to fix it, it might be easier to get that one.

https://www.gumtree.com.au/s-ad/punchbowl/speakers/velodyne-impact-12-subwoofers/1251311942

Good spot, as it is still a current model sub i may go and see how it sounds before i grab this one.

 

23 minutes ago, davewantsmoore said:

The amplifier will contain specific EQ for the driver/box it was designed for......   so only the original driver will be a reliable replacement.

That was the sort of information i was looking for, so sounds like buying older subs with dead drivers isnt an option

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3 hours ago, thorpef1 said:

so sounds like buying older subs with dead drivers isnt an option

Generally, yes.  It depends.

 

Most subwoofers have specific EQ applied to the driver, so that the combined response of the amp/driver/box is flat.

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4 hours ago, thorpef1 said:

Good spot, as it is still a current model sub i may go and see how it sounds before i grab this one.

 

That was the sort of information i was looking for, so sounds like buying older subs with dead drivers isnt an option

You may be able to get a driver that is close enough but the driver itself could be setting you back more than buying a working used sub. If you were going down the path of replacing a driver you would need to either do a 1 for 1 replacement of same  brand and model or run simulations with software to find a suitable replacement.

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The used JBL sub looks like about $800 rrp 2000 model with about 46L internal volume ported design. A repairer might be able to fix the woofer if it is burnt voice coil for maybe $120+ unless the problem is the amp unit then more. It’s really only worth about $50 in that condition with unknown repairs.

 

A Peerless 12 xls woofer is a possible replacement, most 12 inch hifi speaker woofers would be designed for a 75L+/- ported enclosure to get the desired low freq response unless the EQ in the subamp unit kicks it lower. There may be used specific or similar woofer replacements elsewhere on eBay etc. Note the JBL woofer is downfiring with thick roll surround to keep it in place vs other replacement woofers that may not be good for downfiring due to gravity pulling cone down in the long term.

 

A good place to look for possible replacement model woofers is download the free speaker design software WINISD http://www.linearteam.org which has a large data base for possibly 80-90% of woofers ever made and used by manufacturers. If you get the JBL look on the back of the woofer for make and model number. A smaller 8-10 inch woofer might cope given the 47L cabinet volume and retain similar low freq extension but a new panel would be needed to seal it.

 

Most of this too much trouble. There is a Gumtree Sony SAWM40 sub somewhere for $120 which I often recommend to people.

Edited by Al.M
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Thanks for that detailed response AI.M.

 

I don't mind playing around on WINISD (I remember building my car subwoofer years ago) but if it limits my options due to amp and volume it may be easier to find a working one. 

 

So I have bookmarked a few of the velodyne impact 12"

I have also come across the below two and wondering how these would go:

 

KEF psw4000

Focal chorus sw700s

 

What's the consensus on the velodyne vs kef vs focal?

 

I'm also keeping an eye out for a rel 

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7 hours ago, thorpef1 said:

Bump.

 

Whats the consensus on the below:

Velodyne Impact 12 

KEF PSW4000

Focal Chorus SW700S.

 

 

 

From what I've read (no personal experience) the SW700S is quite a tight and dry-sounding woofer, not a boomer. Great for music, and good for home theatre, but not necessarily an outright bruiser.

 

I've repaired KEF subwoofers in the past - the earlier 10" versions often suffered from age-related issues due to a compromised design, but the later models might have rectified this.

 

I have no personal experience with Velodynes.

 

 

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