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Old 7th August 2013, 01:26 PM   #1
Eldam is offline Eldam  France
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Default about resistors type and inductance in passive filters

Hi,

Ceramic resistor are said to have more inductance : the current is reduced when the frequency grows. I ask myself if wze can hear it ? What is the effect : less transparency, smoother high if used in treble filter ?

When two ceramic resistors are in parralel then the inductance is reduced, it's for example in a powersupply like a pi filter maid with several resistors : less noisy, less termal noise too. That's what I read.

i have two ceramic resistor of 4 homs/10 w in parralel in series (so equal to 2 homs/2OW) at the beginning of a second order medium filter. Do (must?) have I to replace them by equivalent or is it possible to exchange with a single NON INDUCTIVE 2 homs/20 watts (or two 3.9 homs/10 Watts because i can't find 4 homs near my home!) to improve the sound quality (medium-woofer is aluminium cone).

For the treble I have a single ceramic resistor of 10 Homs // 1 uF mylar, in series at the beginning at the filter. tweeter is aluminium. Will I hear a difference if i change ceramic witrh a non inductive one ?

It is said to be icing on the cake, but I want to know if I can go wrong or not by changing resistors technology! I don't want to play with the valors of the filters but just tweak up with same values because resistors was broke during soldering new wires.

An experienced fellow wrote to me it can smooth, calm a little some brighness in the treble. Others said to me not change MKT ( but // with polystyren)caps with MKP because I have already transparency and a lake of flesh that MKP caps can't improve (can't be really more meatier)... so I am in the icing of icing on the cake with resistors.

Have you experienced such a thing ?

Last edited by Eldam; 7th August 2013 at 01:29 PM.
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Old 7th August 2013, 02:39 PM   #2
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Default Tunable Paralleling....

I have used multipled paralleled standard resistors (1W) in speaker networks.

Construction was resistors bridging 6.5mm spaced slots in two 0.7mm thick copper strips/busbars (3") long (most slots had 2 resistors fitted).
Another method would be to cut slots (or drill holes..or both) into the edges of two strips of pcb.....it would be much easier to solder/desolder !.

The theory was that this assembly should be very low series inductance, in addition to being relatively high power if needs be.
Another theory was that non WW type resistors might sound different, also values could be readily tuned by adding/deleting/changing individual resistors.
Paralleled capacitors can be done exactly the same way.

I mainly used these assemblies to fine tune the resistance and capacitance values of the Zobel networks - Wikipedia (scroll way down) directly across the terminals of each of the drivers in my 8" two ways.
The tweeter series coupling cap assembly was done in the same way.
I used multiple polypropylene capacitors, bridged with multiple polystyrene caps, including values of polystyrene as high as 1mF (military surplus store gold!)
There might have been a BP electrolytic in the bass driver zobel.

By this method I fine tuned the impedance of the loudspeaker to be flat/constant out to past 40kHz or so.
This tweak/engineering pays great sonic dividends in my experience.
The result was highs that went clean and past ones hearing limits, and bass that resonated a 6 unit apartment block...yup, seriously, and out of a pair 8" two ways 600mm above the floor on stands....ok I was just momentarily clipping a 150W/ch power amp.

So, yes by all means try non 5/10/20W ceramic/cement resistors.....I reckon they sound nicer, much nicer.
Ditto capacitors.

Dan.
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Old 7th August 2013, 02:54 PM   #3
DavidL is offline DavidL  United States
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Waste of time worrying about different resistors. The inductance of a wire wound resistor is so miniscule as to have no effect on the sound. I'd worry more about tuning the room the speakers are in, much larger differences just placing the speakers correctly and fixing room acoustics.
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Old 7th August 2013, 03:06 PM   #4
DavidL is offline DavidL  United States
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Quote:
Originally Posted by Max Headroom View Post
.

By this method I fine tuned the impedance of the loudspeaker to be flat/constant out to past 40kHz or so.
This tweak/engineering pays great sonic dividends in my experience.
The result was highs that went clean and past ones hearing limits, and bass that resonated a 6 unit apartment block...yup, seriously, and out of a pair 8" two ways 600mm above the floor on stands....ok I was just momentarily clipping a 150W/ch power amp.


Dan.
Sorry but if a tweeter is already responding past 20kHz then it's past your hearing ability.

Making the speaker impedance flat does help the sound only in that the amplifier now doesn't have to work as hard if it has a a constantly flat impedance to drive. If the amp wasn't clipping or struggling to begin with though, then it's not going to be a drastic affect on the sound. Perhaps making the bass impedance flat cured a problem you had and lets the amp deliver the power to drive them properly. Hard to say.

All Eldam wants to do is swap resistor types, I don't think it's worth his time.
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Old 7th August 2013, 04:28 PM   #5
Eldam is offline Eldam  France
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Thank you for the answers,

i think I have no problem with driving any impedance curve because my amp is a Chord SPM 1000B (200 W at 8 homs, the double at 4 homs) and the speakers have not a too low curve if I remember (nothing below 3 homs). I ask myself to go or not to nc400 but be scared by a too much tighty touch which is not to good with medium and treble but that's a future story !

In another way I read than good speaker designers prefer sometimes a resistor not only to adapt the speakers units between them but to help the speakers unit and the amp with the "elecromagnetic return" (don't know how you say in english sorry) between these two elements. here the designer was phil Jones with these 85 db Boston Lynfield 400L. These speakers was high end with theirs grand sisters Lynfield 500L (same with more bass) and Boston Acoustics never do better after...

I just talk about the medium (125 to 2500 Htz) and tweeter (the bass has no resistor in serie in the second order filter).

I have to change the resistors in the midrange filter because in one of them the resistors pads are broken. My question is the change of technology can be heard because in theory with cement the impedance is flater than Wirewound resistor then frequency grows. But I heard Non inductive Wirewound like M-resist Mundorf resistor are more transparent. In fact my speakers don't suffer of a lake of transparency and i ask if the growing up impedance with a non inductice WW is enough to change the sound like something harsher for example? Is better to change the cement resistor of the treble with non inductive too (if already changed in the medium filter) or it's no worth because I will never hear a difference ?

Is the low sensitivity of 85 db is important here with resistors in relation to a 95 db speakers if my amp can drive almost any charge like the Chord ?

thank you because I never try and only know theory here...
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Old 7th August 2013, 06:23 PM   #6
DavidL is offline DavidL  United States
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Daryl over at Parts Express, who's opinion I admire said "Non-inductive or not makes no difference in any resistor I have measured up to 20 watts and 100khz."

We are talking about inductance in the micro-henries. Again I state you are not going to hear any difference.
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Old 7th August 2013, 08:28 PM   #7
Eldam is offline Eldam  France
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thank you, it's clearer... so i'm going to buy the cheapest I can get from my local dealer : dayton cement less than 1 euro .
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Old 7th August 2013, 09:14 PM   #8
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Quote:
Originally Posted by DavidL View Post
Daryl over at Parts Express, who's opinion I admire said "Non-inductive or not makes no difference in any resistor I have measured up to 20 watts and 100khz."
I have, but Parts Express doesn't carry them.
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