Help with some Aiwa speakers please - UK Vintage Radio Repair and Restoration Discussion Forum

kirstyd · 14th Apr 2018, 9:23 pm

I saved these from being skipped today. They are Bi wired. Two leads coming from the back, one to the bass unit one to the tweeter. There is some sort of crude crossover unit in the lead to the tweeter [when i say crossover unit there's only one component on it as you can see in the photo] What i want to know is can i just connect the two leads together and use them.

mark_in_manc · 14th Apr 2018, 9:37 pm

You might be able to - but below resonance, the tweeter is stiffness controlled. I have seen the stiffness of such a suspension fail when hit with wideband audio, and the tweeter buckled in time with the bass beat! It would be safer to put a (non-polarised) capacitor in series with the tweeter, which will work like a simple first-order hi-pass filter. I could derive (crappy memory, so I can't just remember) an equation for the pass band for you, but use the largest non-polarised cap in your bits box and see what happens.

The thing will have weird directivity where bass and treble units both work around the de-facto cross-over freq, and it will get weirder as the bass unit 'breaks up' (vibrates not-as-a-solid-piston) at higher frequencies still, but who cares?

(Not me - but then I used to work in the field, which makes me like the shoemaker who can't be ****d to fix the holes in his boots

).

If it bugs you, you could even wind an air-cored inductor to put in series with the LF unit, which will roll it off for you. Or really go for it and look up the equations for Linkwitz-Riley 2nd-order cross-over networks - a cap and an inductor on each and every drive unit.

kirstyd · 14th Apr 2018, 9:43 pm

Thank you Mark for that in depth explanation .I will give it a go when my head stops hurting

Edward Huggins · 15th Apr 2018, 10:18 am

The OP's last photo does just shows one lead coming forn the rear of the enclosure which does not suggest "Bi-Wired" which would be unlikely in a speaker of this class.
A good general purpose tweeter filter (high-pass) capacitor is a 2.2 uf which approximately crosses over at around 3,500 c.p.s. Japanese Music Centre speakers were always a weak point, so do no expect too much from these.

paulsherwin · 15th Apr 2018, 11:09 am

Music centre speakers don't usually have a proper crossover. The woofer is directly connected to the signal, and the tweeter is connected via a non polarised capacitor of around 2uF (the really cheap ones just use a polarised electrolytic). These will be reasonable workshop or bedroom speakers, but as Edward suggests you shouldn't expect breathtaking performance.

I wouldn't bother fitting a proper crossover to them unless you want to experiment or you have something suitable going spare.

ms660 · 15th Apr 2018, 11:58 am

That component looks like a 2 ohm 5 watt wire wound to me.

Lawrence.

roffe · 15th Apr 2018, 7:24 pm

According to these manuals the speakers are meant to be used in a satellite system.
https://www.manualslib.com/manual/72...87.html?page=2
p 1-2
https://www.***********/document/163.../Aiwa-Nsx-Sz80
p4

kirstyd · 15th Apr 2018, 7:38 pm

the speakers were part of the usual cheap system [two tape decks /CD player and radio oh yes and the usual handful of flashing lights .I dont expect fantastic sound from them i just dont want to damage them or whatever i connect them to .Here is a photo of the back .The blue wire goes directly to the bass unit while the other lead goes to the tweeter via the little circuit board

mhennessy · 15th Apr 2018, 8:14 pm

You will need to add (at the very least) a capacitor in series with the tweeter. Start with 4u7 - ideally non-polarised, but anything would do for testing purposes.

If you omit the cap, the tweeter will get damaged as soon as you turn up the volume. Even quiet volumes might be enough to cause harm.

Try it and see. Vary the value of the cap. Once you've found a value that sounds OK to you, mount it inside the box and re-wire things so you've only got one pair of wire emerging from the back.

Originally, the unit will have contained 4 amplifiers - one for each drive unit. There would have been a crossover implemented using low power electronics. Without seeing a service manual there's no way to predict how complicated this was, but as components that are dealing with small line-level signals are cheap, it's possible that it might have been really quite elaborate. Or not...

This approach - the so-called "active crossover" - is used by many professional speakers at all price points, and carries a certain cachet as a result. Hence here, it would have been done primarily for marketing reasons. I remember when these started appearing - some of them sounded really quite reasonable. It's surprising how good a cheap and nasty set of drive units can be made to sound with a bit of well-judged equalisation.

andrewn · 18th Apr 2018, 8:54 pm

I was given a pair of Aiwa speakers that had a similar bi-wire system. It has a wire for the woofer and spring clip terminals for the "surround" which is three tweeters pointing at different angles. The woofer is 8ohm and the tweeters are 16ohm. I simply wired them up in parallel to use with my own amp and it works fine. Although I don't have the exact hifi, I have a similar Aiwa unit that has mating connectors marked main and surround. They are just connected together inside! Nothing more than a normal stereo output with unnecessary wiring.

14th Apr 2018, 9:23 pm	#1
kirstyd Heptode Join Date: Mar 2014 Location: Leeds, West Yorkshire, UK. Posts: 902	Help with some Aiwa speakers please I saved these from being skipped today. They are Bi wired. Two leads coming from the back, one to the bass unit one to the tweeter. There is some sort of crude crossover unit in the lead to the tweeter [when i say crossover unit there's only one component on it as you can see in the photo] What i want to know is can i just connect the two leads together and use them. Attached Thumbnails

14th Apr 2018, 9:37 pm	#2
mark_in_manc Octode Join Date: Nov 2011 Location: Manchester, UK. Posts: 1,875	Re: help with some Aiwa speakers please You might be able to - but below resonance, the tweeter is stiffness controlled. I have seen the stiffness of such a suspension fail when hit with wideband audio, and the tweeter buckled in time with the bass beat! It would be safer to put a (non-polarised) capacitor in series with the tweeter, which will work like a simple first-order hi-pass filter. I could derive (crappy memory, so I can't just remember) an equation for the pass band for you, but use the largest non-polarised cap in your bits box and see what happens. The thing will have weird directivity where bass and treble units both work around the de-facto cross-over freq, and it will get weirder as the bass unit 'breaks up' (vibrates not-as-a-solid-piston) at higher frequencies still, but who cares? (Not me - but then I used to work in the field, which makes me like the shoemaker who can't be ****d to fix the holes in his boots ). If it bugs you, you could even wind an air-cored inductor to put in series with the LF unit, which will roll it off for you. Or really go for it and look up the equations for Linkwitz-Riley 2nd-order cross-over networks - a cap and an inductor on each and every drive unit.

14th Apr 2018, 9:43 pm	#3
kirstyd Heptode Join Date: Mar 2014 Location: Leeds, West Yorkshire, UK. Posts: 902	Re: help with some Aiwa speakers please Thank you Mark for that in depth explanation .I will give it a go when my head stops hurting

15th Apr 2018, 10:18 am	#4
Edward Huggins Dekatron Join Date: Sep 2015 Location: Southwold, Suffolk, UK. Posts: 8,340	Re: help with some Aiwa speakers please The OP's last photo does just shows one lead coming forn the rear of the enclosure which does not suggest "Bi-Wired" which would be unlikely in a speaker of this class. A good general purpose tweeter filter (high-pass) capacitor is a 2.2 uf which approximately crosses over at around 3,500 c.p.s. Japanese Music Centre speakers were always a weak point, so do no expect too much from these. __________________ Edward.

15th Apr 2018, 11:09 am	#5
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,970	Re: Help with some Aiwa speakers please Music centre speakers don't usually have a proper crossover. The woofer is directly connected to the signal, and the tweeter is connected via a non polarised capacitor of around 2uF (the really cheap ones just use a polarised electrolytic). These will be reasonable workshop or bedroom speakers, but as Edward suggests you shouldn't expect breathtaking performance. I wouldn't bother fitting a proper crossover to them unless you want to experiment or you have something suitable going spare.

15th Apr 2018, 11:58 am	#6
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: Help with some Aiwa speakers please That component looks like a 2 ohm 5 watt wire wound to me. Lawrence.

15th Apr 2018, 7:24 pm	#7
roffe Hexode Join Date: Nov 2003 Location: Linkoping, Sweden Posts: 493	Re: Help with some Aiwa speakers please According to these manuals the speakers are meant to be used in a satellite system. https://www.manualslib.com/manual/72...87.html?page=2 p 1-2 https://www.***********/document/163.../Aiwa-Nsx-Sz80 p4

15th Apr 2018, 7:38 pm	#8
kirstyd Heptode Join Date: Mar 2014 Location: Leeds, West Yorkshire, UK. Posts: 902	Re: Help with some Aiwa speakers please the speakers were part of the usual cheap system [two tape decks /CD player and radio oh yes and the usual handful of flashing lights .I dont expect fantastic sound from them i just dont want to damage them or whatever i connect them to .Here is a photo of the back .The blue wire goes directly to the bass unit while the other lead goes to the tweeter via the little circuit board Attached Thumbnails

15th Apr 2018, 8:14 pm	#9
mhennessy Dekatron Join Date: Jul 2007 Location: Evesham, Worcestershire, UK. Posts: 4,244	Re: Help with some Aiwa speakers please You will need to add (at the very least) a capacitor in series with the tweeter. Start with 4u7 - ideally non-polarised, but anything would do for testing purposes. If you omit the cap, the tweeter will get damaged as soon as you turn up the volume. Even quiet volumes might be enough to cause harm. Try it and see. Vary the value of the cap. Once you've found a value that sounds OK to you, mount it inside the box and re-wire things so you've only got one pair of wire emerging from the back. Originally, the unit will have contained 4 amplifiers - one for each drive unit. There would have been a crossover implemented using low power electronics. Without seeing a service manual there's no way to predict how complicated this was, but as components that are dealing with small line-level signals are cheap, it's possible that it might have been really quite elaborate. Or not... This approach - the so-called "active crossover" - is used by many professional speakers at all price points, and carries a certain cachet as a result. Hence here, it would have been done primarily for marketing reasons. I remember when these started appearing - some of them sounded really quite reasonable. It's surprising how good a cheap and nasty set of drive units can be made to sound with a bit of well-judged equalisation.

18th Apr 2018, 8:54 pm	#10
andrewn Pentode Join Date: Aug 2008 Location: Taunton, Somerset, UK. Posts: 135	Re: Help with some Aiwa speakers please I was given a pair of Aiwa speakers that had a similar bi-wire system. It has a wire for the woofer and spring clip terminals for the "surround" which is three tweeters pointing at different angles. The woofer is 8ohm and the tweeters are 16ohm. I simply wired them up in parallel to use with my own amp and it works fine. Although I don't have the exact hifi, I have a similar Aiwa unit that has mating connectors marked main and surround. They are just connected together inside! Nothing more than a normal stereo output with unnecessary wiring.