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Help with a speaker tweak

NewtonSheep

NewtonSheep

pfm Member
Hi, first of all I need to say that I don't understand electrical/electronics at all; plug it in, switch it on, listen - that's as complex as it gets :(

So, bearing that in mind...

I've just read this article http://www.10audio.com/gallo_ref3-1.htm and want to try out the resister tweak on my Ref 3.1's.

The problem is I can't source the Mills resistor in the U.K.

Can anyone point me at an equivalent component? I've looked at marlin, Farnell, etc, but don't understand the various properties :rolleyes:

TIA!
Steve
 
Rapid electronics are very good for small quants of parts

All you want is a power resistor of, say, 3-5w or more rating, and a range of reistances to try (if that link is to be believed)

Pick a few from here - cheap enough to try several.

https://www.rapidonline.com/Catalogue/Searches?query=wirewound

(nothing to magical about Mills, except some are 'low inductance (Ayrton-Perry) wound - which most reputable parts will also be; that said, in this application the potential inductance contributed by the resistor will be about 1/100 - 1/10000th of SFA to do with the result*.

*serious point: springing for 'low inductance' packages for LF crossover parts is daft when there's usually a couple of meters of speaker wire in the way, contributing at least a couple of microhenrys, and whatever inductor(s) are in the low-pass section of the crossover, contributing several thousand times as much.

The inductance of a resistor is fundamentally proportional to its length, at roughly 1nH/mm... 5 or 6 orders smaller than these things that dominate. Even for HF filters above 10Khz, the need is ..arguable (it's still two orders of magnitude below the speaker lead...) ;)
 
Thanks Martin. I didn't understand a word of it! :confused::D

Actually, the Gallo speaker doesn't use a crossover, so does what you say still apply?
 
I've just read the Galo marketing advert you have linked to and it's fair to say it is very partisan in its views, in other words - it's largelely bollocks! It's not entirely untrue but there are a whole lot of further related issues ignored or left unexplained.
 
YNWOAN said:
I've just read the Galo marketing advert you have linked to and it's fair to say it is very Parisian in its views, in other words - it's largelely bollocks! It's not entirely untie but there are a whole lot of issues ignored or left unexplained.
Click to expand...

I'm willing to give it a go for the price of a CD, but thanks for the technical input ;)
 
I agree with YNWOAN actually, but a couple of quid spent at Rapid to buy a few pairs of 3w power resistors in various values is harmless.
 
intothevoid said:
Actually, the Gallo speaker doesn't use a crossover, so does what you say still apply?
Click to expand...
Actually, it does.

Both of the dual midrange drivers and the tweeter of the Gallo Reference 3.1 are designed specifically for their respective roles in this particular speaker system. There is a single inductor for the woofer crossover and the low end of the midrange has a single crossover component for a smooth transition to the woofer. The tweeter uses a step-up/impedance matching transformer to increase its signal level and to reduce its characteristically high impedance. But there is no crossover between the midrange and the tweeter. This is the revolutionary genius of the Gallo Reference 3.1 loudspeaker.
Click to expand...
Don't confuse a filter with a crossover. One is cause; the other effect. The inductor on the woofer and the capacitor on the mid are electrical filters. They effect the crossover from LF to MF. Same thing goes for the MF/HF crossover. Except that the midrange uses the mechanical / voice-coil inductance to limit its upper range and the HF uses a transformer to effect the transition.
 
intothevoid said:
Hi, first of all I need to say that I don't understand electrical/electronics at all; plug it in, switch it on, listen - that's as complex as it gets :(

So, bearing that in mind...

I've just read this article http://www.10audio.com/gallo_ref3-1.htm and want to try out the resister tweak on my Ref 3.1's.

The problem is I can't source the Mills resistor in the U.K.

Can anyone point me at an equivalent component? I've looked at marlin, Farnell, etc, but don't understand the various properties :rolleyes:

TIA!
Steve
Click to expand...

I would ask your Gallo dealer, because that article seemed more froth than information. Are we saying that the speaker bass section has 2 sets of inputs and each is for a different voice coil on the bass driver? If one coil is driven by an amp, then the bass will be different and louder if 2 amps drive 2 coils. If you connect a resistor across an unused coil you will get a different sound again. Focal were flogging this idea back in the 1980s with their bass drivers. You MUST NOT connect a resistor across terminals which are being driven by an amp. Check with a dealer.
 
ok, thanks for your input guys. Maybe I'll give it a miss.

PS. I still don't understand a word of the technical explanations.
 
The way I read it, the 'sub in' inputs drive second voice coil on the bass units. Mad way of doing things, really...

Anyway - adding a (passive) resistance across this second VC - the 'sub in' terminals - will have a moderate effect on the bass response, by messing with the effective losses. It's a very crude way of manipulating the efficiency and damping of the bass unit - with more effect if you are using amps with high-ish output impedance, such as the valve amps in the linked article.

Amazing to see the article's author was using a powered amp here with zero input - imagining it would provide 'active damping', when a piece of wire to short the terminals out would have given the same effect, for free.

Summary: lousy, crude and wasteful tone control.
 
I wish I understood what any of this meant :(

What really puzzles me is why connecting the two terminals together has any affect at all given there's no input signal.

Pandora. Box. Open.
 
it seems the speaker has two voice coils on the same former.
Use an amp, push current through the voice-coil immersed in the speakers magnetic field - the coil moves, and with it the speaker cone = sound out.

But the unconnected second voice coil attached to this cone is also being moved through the driver's magnetic field, so it works like a generator - a voltage will appear across its terminals.

Connect those terminals together with a wire link, or a resistor, and the amplifier has to do more work - because the second voice coil is now acting like a brake on the speaker cone's movement. Changing the resistor value changes the added braking. It will be none when open (unconnected), least effect for a high value resistor (little current flow) to most when you use a very low value resistor, a wire link - or a powered amplifier with no applied signal like the article! And essentially that's why the article noted such a config gave 'lean' /'taught' bass.

Any help?
 
Martin has nailed it.

Why would you drive a car with a foot partially on the brakes?
 
martin clark said:
I agree with YNWOAN actually, but a couple of quid spent at Rapid to buy a few pairs of 3w power resistors in various values is harmless.
Click to expand...

Cheers Martin :). However, as you say, it's an easy experiment and only costs a few pounds; the writers logic seems flawed to me but harmless to try. As others have already stated, the required resistors can be bought in the UK, HiFi Collective are easy to deal with.

On second thoughts I wouldn't do it. I don't know that Galo model very well and it does sound like it has an unusual dual voicecoil arrangement that is seperately wired to external connectors.

Edit: ignore the above negative comment as I somehow failed to notice that the OP owns the very Galo speakers discussed. As Martin says, an easy and cheap thing to try and nothing lost.
 
Actually I have heard them on a couple of occasions - not my first choice (as if that matters), but very compact footprint and a fairly bold/clear sound as I recall. If it's what you have , why not push it as far as possible?


- isn't that why we're all here ; )
 
James said:
Why would you drive a car with a foot partially on the brakes?
Click to expand...


to stretch an a analogy grossly - because you have FWD and a big turbo? had my fill of overboosted Saabs, and a judicious dab of brakes was a useful skill to get them to turn-in smartly ;)

[size=-2] or just rotate on the spot until you learned moderation ...![/size]
 
martin clark said:
to stretch an a analogy grossly - because you have FWD and a big turbo? had my fill of overboosted Saabs, and a judicious dab of brakes was a useful skill to get them to turn-in smartly ;)

[size=-2] or just rotate on the spot until you learned moderation ...![/size]
Click to expand...
If only you could apply the brake resistors at will. ;)
 
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