Sub Woofer

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JohnG
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#1 Sub Woofer

Post by JohnG »

My first post beyond my introduction to the forum, here goes.

I have many wishes when it comes to speakers I want to experiment with, Stacked Quads as I own 50% of that set up.
I also want to start the investigation and collection of drivers to build a 3 way open baffle speaker. I would like to begin collecting towards the end of 2017, learning a bit more about drivers throughout the year.
In the short term and maybe the longterm I am using a Tannoy Mercury 2.5, stolen from my sons bedroom along with his Cambridge Audio 540 Azur.
I have developed what I believe is a synergy between my single monoblock 845 power amp and these components, I am really enjoying the performance
and it is as enjoyable a listen as anything I heard at Scalford Show recently.
I am scratching my head at the separation and imaging. I can't wait to go full stereo.
There is a obvious weakness in the speakers bass department, and as a simple attempt at a fix, I am thinking of adding a sub woofer to work with these speakers. The monoblock speaker cable terminals are sharing a Black/Red wire from each speaker. The RCA Socket has a "Y" splitter socket.
This is the set up I refer to as Faux Stereo.
Is there any knowledge of a very affordable sub woofer with a decent performance,that would lend itself to my temporary set up, I could experiment with to help the bass department ?

John
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IslandPink
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#2 Re: Sub Woofer

Post by IslandPink »

I suppose a few questions would help set the scene for options :
Does it have to be commercial involving no self-build ?
Does it have to be compact or can it be big - ie. a big sealed box or a big OB bass 'helper' ?
Does it have to look nice ( ie. suitable for front room with wife ) or can it be an ugly prototype of a thing lik ein my house ?
My own suggestions will not be much about commercial subs, more about types of DIY concepts aimed more at performance than convenience !
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chris661
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#3 Re: Sub Woofer

Post by chris661 »

A quick and easy way to get bass on an open baffle is just to throw an Eminence Alpha-15 a side at it. They're not my favourite woofer, but they're very convenient to use in that regard.

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#4 Re: Sub Woofer

Post by IslandPink »

Q's a bit high on the Alpha though isn't it Chris ? - bit loose ?
I know James didn't recommend them.
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#5 Re: Sub Woofer

Post by chris661 »

The high Qts gives a bump in output at resonance, and brings with it a slight tendency to ring there.
The bump means that it counter-acts the bass rolloff inherent in dipole systems, though, and gives a response that's roughly flat from 40Hz up to the first dipole peak (which an inductor can knock down handily - sized to be -3dB around 150Hz IIRC).

As I said, it's a cheap and easy way to get bass on an open-baffle system. I can't comment much on the sound of the thing since it's been a while since I heard anything with them in, and when I did it was Owston (Ali's OBs), where the room wreaks havoc on most systems.
The tiny magnets and limited excursion aren't for me, that's for sure. I'd rather have something with a very powerful motor and EQ the resulting bass rolloff.
I believe I've also heard the Beta-15 drivers, which feature a more sensibly-sized motor. IIRC, those were on the end of a valve amp (Nick's 211 maybe) so that might've added an ohm or two output impedance which would push the Q up on that one, too. I do remember preferring the Beta-15 drivers over the Alpha-15s, but they were in different systems with different amps, crossovers, room positions, etc, so it's difficult to draw any solid conclusions on the matter.

Chris
SimonC
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#6 Re: Sub Woofer

Post by SimonC »

IslandPink wrote: Wed Mar 29, 2017 11:18 am Q's a bit high on the Alpha though isn't it Chris ? - bit loose ?
I know James didn't recommend them.
Martin King has a well sorted OB design for the Alpha where he exploits the high Q as Chris describes. He gives a nice write up of the whole design process and why he selected the alpha. Its paired to an FE103, but it should work just fine in its own right as a bass helper.

http://www.quarter-wave.com/OBs/OB_Design.pdf
http://www.quarter-wave.com/OBs/OB_Design_Part_2.pdf

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#7 Re: Sub Woofer

Post by cressy »

Id look at pc speaker systems, i had a creative soundworks setup a few years back that had a small sub and some little satellites, the sub wasnt bad at all for what it was. You may find some second hand bargains in that area. Jbl do some nice ones
JohnG
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#8 Re: Sub Woofer

Post by JohnG »

Thank you for your replies and the encouragement.

Firstly I do not have a preferance for a Brand or a DIY attempt. The appearance does not matter in the initial stages, as for wife friendly, my darling, lovingly calls the esl 57 the " wash boards ". I think a Big OB will look great with a vase of flowers masking it.
I am old school HiFi World influenced, so i am happy to think outside the REL box if this is sensible.
I am thinking of this as a new challenge, and now the OB Sub has been mentioned, the project could become my first dip of my toes into a OB 3 way.
I can search out a alternative set of Bass drivers to the alphas, if this makes sense, for the future project, and utilise them on this system in the short term.
I am open to all recommendations and set up guidance. I think I should say at this stage a budget of no more than £300 will be a good beginning.
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Dr Bunsen Honeydew
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#9 Re: Sub Woofer

Post by Dr Bunsen Honeydew »

Why do people think sub woofers are a good idea, they are musically disastrous especially the REL ones. What ever you do not connect sub woofer to the speaker outputs of power amps, it is stupid and it blows up some amps. Real bass is musical, artificial bass is just hi-fi.
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andrew Ivimey
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#10 Re: Sub Woofer

Post by andrew Ivimey »

I'm going to think about that last sentence. It has immediate appeal.
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#11 Re: Sub Woofer

Post by IslandPink »

It's a delicate business putting some low bass to a set of ESL's but OB has a better chance than most methods. You could check out Jazzman's Ripole bass comments too :
http://www.audio-talk.co.uk/phpBB3/view ... f=4&t=5794
I just tried going into that thread and got a never-seen-before error message, though ... ?
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andrew Ivimey
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#12 Re: Sub Woofer

Post by andrew Ivimey »

How did you get past all that gobbledegook! ?
Philosophers have only interpreted the world - the point, however, is to change it. No it isn't ... maybe we should leave it alone for a while.
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#13 Re: Sub Woofer

Post by chris661 »

Dr Bunsen Honeydew wrote: Wed Mar 29, 2017 7:54 pm Why do people think sub woofers are a good idea, they are musically disastrous especially the REL ones. What ever you do not connect sub woofer to the speaker outputs of power amps, it is stupid and it blows up some amps. Real bass is musical, artificial bass is just hi-fi.
Subwoofers are an excellent idea.
They take the strain of producing the very bottom-end material away from the midrange drivers that have more important things to be doing.

Note that simply adding a sub to an existing system in the way you've described doesn't achieve this. You've got to implement a proper crossover, preferably before the amplifiers. That way, your nice valve amp isn't wasting headroom flapping the little midrange drivers around, so the critical bits of the system get a much easier life.
Connect a big solid-state amp to a large cone to produce the bottom-end stuff and off you go. You'll extend your bass response down an octave, and reduce distortion in the midrange. Tell me, how's that musically disastrous?

The other thing is that people often set their subs way too loud. A sub needs to be basically inaudible, until you switch it off.

Chris
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shane
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#14 Re: Sub Woofer

Post by shane »

andrew Ivimey wrote: Wed Mar 29, 2017 11:24 pm How did you get past all that gobbledegook! ?
I think this is where the link was supposed to go:

http://jazzman-esl-page.blogspot.co.uk/ ... y.html?m=1
The world looks so different after learning science. For example, trees are made of air, primarily. When they are burned, they go back to air, and in their flaming heat is released the flaming heat of the Sun which was bound in to convert air into tree.
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Toppsy
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#15 Re: Sub Woofer

Post by Toppsy »

chris661 wrote: Thu Mar 30, 2017 9:32 am
Dr Bunsen Honeydew wrote: Wed Mar 29, 2017 7:54 pm Why do people think sub woofers are a good idea, they are musically disastrous especially the REL ones. What ever you do not connect sub woofer to the speaker outputs of power amps, it is stupid and it blows up some amps. Real bass is musical, artificial bass is just hi-fi.
Subwoofers are an excellent idea.
They take the strain of producing the very bottom-end material away from the midrange drivers that have more important things to be doing.

Note that simply adding a sub to an existing system in the way you've described doesn't achieve this. You've got to implement a proper crossover, preferably before the amplifiers. That way, your nice valve amp isn't wasting headroom flapping the little midrange drivers around, so the critical bits of the system get a much easier life.
Connect a big solid-state amp to a large cone to produce the bottom-end stuff and off you go. You'll extend your bass response down an octave, and reduce distortion in the midrange. Tell me, how's that musically disastrous?

The other thing is that people often set their subs way too loud. A sub needs to be basically inaudible, until you switch it off.

Chris
I totally agree with you Chris. Unless ones speakers are designed to go down to a true 30Hz and are an easy load to drive then a sub can be most beneficial if used as you say. My own preference is to use two subs though rather than the generally recommended single sub-woofer speaker for a stereo set up.
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