The great speaker wire debate rolls on...

Moderator: JackD201

Postby Guest » Wed Nov 09, 2005 5:52 pm

audiophileman2002 wrote:All I'm saying is that cables are tested not just with a simple LCR meter. There are other test instruments involved like an oscilloscope, signal generator, etc. Other influences cannot be quantified by the LCR but can be seen in a scope. There would be differences. As to filtering in the pre-amp and power amp (specially the mighty 3 watt) you have limitations specially the no feedback pre-amps and power amps. That is why you have the SET which is single ended.
If one is a believer in the ordinary zip cords fine, if one is a believer in the high end ones that is also fine. After all we all live in free countries and pretty much can do what we want. Right? The most important issue is we use what we are happy with? Or shall I say one is happy on what one can hear.


Agree that being happy with your cable is utmost. For wire testing, it is actually overkill to use an oscilloscope or a signal generator. The representation I did of the wire is:

a resistor in series with an inductor connected to a cap going into the opposite wire.

Since, the components are passive, a good LCR meter would do as I am testing vs frequency. Pls check the specs of the Agilent 4284A before you rule it out. I am acutely aware of what test instruments to use otherwise, I will be out of a job.

I am not prejudging you or anybody but I don't believe that you studied or experimented the material you discussed. My sincerest apologies if I have offended you.

Would like to recommend that you read the Art of Electronics by Horowitz and Hill specially on the filters section. The book Electronic Circuits by John D. Ryder is also good. Read on Ch 12 - Feedback. And, download a free version of Symetrix. You can run your simulations here and see for yourself what actual circuit will behave. BTW, we use this software at the Advanced Engineering dept. I can share with you some of the libraries we have developped.
Guest
 

Postby rascal101 » Wed Nov 09, 2005 6:10 pm

audiophileman2002 wrote:All I'm saying is that cables are tested not just with a simple LCR meter. There are other test instruments involved like an oscilloscope, signal generator, etc. Other influences cannot be quantified by the LCR but can be seen in a scope. There would be differences. As to filtering in the pre-amp and power amp (specially the mighty 3 watt) you have limitations specially the no feedback pre-amps and power amps. That is why you have the SET which is single ended.
If one is a believer in the ordinary zip cords fine, if one is a believer in the high end ones that is also fine. After all we all live in free countries and pretty much can do what we want. Right? The most important issue is we use what we are happy with? Or shall I say one is happy on what one can hear.


Agree that being happy with your cable is utmost. For wire testing, it is actually overkill to use an oscilloscope or a signal generator. The representation I did of the wire is:

a resistor in series with an inductor connected to a cap going into the opposite wire.

Since, the components are passive, a good LCR meter would do as I am testing vs frequency. Pls check the specs of the Agilent 4284A before you rule it out.

I am not prejudging you or anybody but I don't believe that have been thorough in your study or experimentation of the material you discussed.

Would like to recommend that you read the "Art of Electronics" by Horowitz and Hill specially on the filters section. The book "Electronic Circuits" by John D. Ryder, read on Ch 12 - Feedback. For vacuum tubes, the "Analysis and Design of Electronic Circuits" by PM Chirlian has a good discussion in amplifier classes (for tubes). Also you may want to download a free version of Symetrix. You can run your simulations here and see for yourself what actual circuit will behave.
rascal101
Citizen
Citizen
 
Posts: 685
Joined: Mon May 30, 2005 5:05 pm

Postby rascal101 » Thu Nov 10, 2005 12:52 pm

Sirs,

I would just like to point out that a constant current to an inductive load (speaker) is a recipe for a light bulb. Pls remember that an inductor stores current and needs to be able to discharge it. In a constant current scenario there is no discharge as such, current will be converted to heat, heat to light and after some time ... lights out. If the speaker inductance is extremely low it will definitely be a bulb but since it is in a few mH ...

Also, pls remember that the vacuum tube amplifier is transformer coupled at the output stage. As such, the transformer cannot be a constant current source nor will it tolerate a constant current source.

BTW, a DC motor has a constant voltage source but the current to the motor varies with time.

I hope this clears things.

Thank you.

Rascal101
rascal101
Citizen
Citizen
 
Posts: 685
Joined: Mon May 30, 2005 5:05 pm

Postby s2kov » Tue Nov 15, 2005 4:58 pm

rascal101,

It would be better to test the frequency over gain response of the cable with constant input signal level. A Vector and Spectrum Analyzer that ranges from DC to 30KHz (and up) will do the job! :)
User avatar
s2kov
Citizen
Citizen
 
Posts: 697
Joined: Thu Sep 18, 2003 3:56 pm
Location: Ang Mo Kio

Postby rascal101 » Tue Nov 15, 2005 6:02 pm

We have a Spectrum Analyzer and it never crossed my mind that I should use it to test cables. About gain ... for a wire ... from DC to 30KHz do you think it will change? I will agree if we are testing the feedback loop for an amp or a switching power supply.

Wires ... wires ... wires ... don't know why it is a big deal. Just made a test to quantify R, L and C and see where it stands. With measurements in the picofarad (1 x 10^-12) and microhenry (1 x 10^-6) and milliohm (1 x 10^-3) is this really that big a deal.

For a peak to peak voltage signal of 40V and typical values seen during testing:

for resistor (100mohm) = 0.1ohm
for inductor (1uH): Xl = 2*pi*f*L = 2*pi*20000*1e-6 = 0.126ohm
for capacitor (500pF) : Xc = 1/(2*pi*f*C) = 1/(2*pi*20000*500e-12) = 15915.5ohm
for speaker (8ohm): Zspk = 8ohm

Z (capacitor, speaker) = Xc x Zspk / (Xc + Zspk) = 8*15915.5/(8+15915.5) = 7.996ohm

Voltage seen by the speaker = Vin x Z / (Z + resistor + Xl) = 40*7.996/(7.996+0.1+0.126)
= 38.9V

Further computation shows a loss of 2.75% on peak signal.

So for 1V peak to peak signal, speaker only sees 972.5mV or a loss of 27.5mV.

Pls note that these computations are at 20KHz. At 10KHz capacitance is higher as such we can expect higher voltage seen by speaker.

Based on above information and computation, parasitics hardly represents an issue that most of us need to deal with. My family and my neighbors hardly hear any difference.

Notes:
1. On the ordinary two wire the capacitance is much less than 500pF (check the specs of the Goertz or other exotic cable configurations)
2. The loss on the 4ohm speaker is double that of the 8ohm ~ 5%

Rascal101
rascal101
Citizen
Citizen
 
Posts: 685
Joined: Mon May 30, 2005 5:05 pm

Postby s2kov » Tue Nov 15, 2005 6:40 pm

Gain flatness across audio frequencies is what i mean. You're right with your computations. Still consider the actual performance of the cable if the specs were met, that is why i am suggesting the use of Spectrum Analyzer since this will actually sees the behaviour of the load being tested. :)
User avatar
s2kov
Citizen
Citizen
 
Posts: 697
Joined: Thu Sep 18, 2003 3:56 pm
Location: Ang Mo Kio

Postby rascal101 » Tue Nov 15, 2005 7:20 pm

Sir s2kov,

Don't know about bringing speakers to the office and setting it up. I wouldn't do it for wire testing. Tinatamad na ako. I would rather do this things in excel or on Simetrix (kung wires lang). You can simulate the speaker circuit and wire including their parasitics at Simetrix.

I want to move on amplifiers now. Have plans to build one as I've had work on the output stage. Also, want to work on further circuit enhancements to my cd player.

I'll get more thrill out of these exercises.

Rascal101
rascal101
Citizen
Citizen
 
Posts: 685
Joined: Mon May 30, 2005 5:05 pm

Postby s2kov » Tue Nov 15, 2005 11:26 pm

rascal101,

No problem bro! :) On my field of work, we don't rely on simulation since the program doesn't see the actual performance of the cable and only the Spectrum Analyzer can see and tell us how it is behave across frequency band! :)
User avatar
s2kov
Citizen
Citizen
 
Posts: 697
Joined: Thu Sep 18, 2003 3:56 pm
Location: Ang Mo Kio

Postby Guest » Wed Nov 16, 2005 10:20 am

s2kov,

1. Maganda siguro set-up niyo ng spectrum analyzer. Maraming trabaho kapag nag-set up ako ng ganito.
2. Dinadaan namin sa gain/phase analyzer ang pagsukat ng gain/phase response vs frequency.

Sample ng gain/phase plot. Iyung malabong litrato sa gitna ay ako kumukuha ng litrato :)
Image

Cheers,

Rascal101
Guest
 

Postby tony » Wed Nov 16, 2005 10:57 am

hmmm... why is my aiwa mini compo capable of reproducing pounding bass and crashing cymbals on a meter of gage22 dinky flatwire? i wonder why.....
User avatar
tony
Fanatic
Fanatic
 
Posts: 1882
Joined: Tue Jun 24, 2003 7:18 am
Location: Pasig City....

Postby s2kov » Wed Nov 16, 2005 7:40 pm

rascal101,

See, that's my point! :) Don't just rely on the simulation and specs. Still, the analyzer will tell you the performance of the cable! :)
User avatar
s2kov
Citizen
Citizen
 
Posts: 697
Joined: Thu Sep 18, 2003 3:56 pm
Location: Ang Mo Kio

Postby tony » Thu Nov 17, 2005 8:22 am

if i had a apectrum analyser, i would use it to find out the frequency response on amp circuits, cables are boring.
User avatar
tony
Fanatic
Fanatic
 
Posts: 1882
Joined: Tue Jun 24, 2003 7:18 am
Location: Pasig City....

Postby arnoldc » Thu Nov 17, 2005 8:48 am

tony, may alam kang facility who can do this for our products? THD, FR, etc. measurements?
arnoldc
Legend
Legend
 
Posts: 14118
Joined: Mon Jan 20, 2003 2:22 pm
Location: Makati

Postby Guest » Thu Nov 17, 2005 9:38 am

Sir joan2, s2kov, arnoldc,

Puwede ba tayo magkaroon ng pulong pulong para makabili tayo ng gain/phase analyzer? Laking tulong nito sa atin kung mayroon tayo nito. Kapag mag pa patest kasi baka lalong mas mahal. Tapos ilang beses mo rin naman gagawin iyung test dahil kailangan mo kunin iyung phase margin sa iba't ibang load at line voltage condition. Napansin ko rin na maraming members ang nagkakahilig mag experiment.

Anong say niyo?

Rascal101
Guest
 

Postby s2kov » Thu Nov 17, 2005 9:50 am

master tony,

That's what we're doing with my job although it is boring but calibration in the whole chain is very important to get accurate measurement across frequency band!:D When testing the amp, i have several test equipment i am using aside from spectrum analyzer (such as; scalar analyzer, power meter/sensor, sweep synthesizer, frequency counter). Those equipment were being used to amp ranges from 1Watt to 3KWatt and from Solid State to Travelling Wave Tube to Klystron Tube! :)
User avatar
s2kov
Citizen
Citizen
 
Posts: 697
Joined: Thu Sep 18, 2003 3:56 pm
Location: Ang Mo Kio

Postby diego » Thu Nov 17, 2005 9:54 am

presently using kenwood speaker wires and noticed that the wires are solid (a little less than the size of paper clips) . would this have a difference in sound as compared to wires with thin strands. tks
diego
Citizen
Citizen
 
Posts: 147
Joined: Tue Oct 12, 2004 11:33 am

Postby arnoldc » Thu Nov 17, 2005 9:55 am

andy, eh baka naman pwedeng ikaw na mag measure para sa amin? with compensation of course ;)
arnoldc
Legend
Legend
 
Posts: 14118
Joined: Mon Jan 20, 2003 2:22 pm
Location: Makati

Postby tony » Thu Nov 17, 2005 12:41 pm

oo nga andy, pwede ba tayo dyan?

of course there are diy sweep analysers i saw at popular electronics magazines, this is another option.

tubelab.com from diyaudio uses his pc to do measurements, have been trying to contact him but no luck so far.
User avatar
tony
Fanatic
Fanatic
 
Posts: 1882
Joined: Tue Jun 24, 2003 7:18 am
Location: Pasig City....

Postby tony » Thu Nov 17, 2005 12:46 pm

arnoldc wrote:tony, may alam kang facility who can do this for our products? THD, FR, etc. measurements?


i suspect Mr. Jose Marie Gonzales? of G records might have this lab.

i do not know how to get in touch with him.
User avatar
tony
Fanatic
Fanatic
 
Posts: 1882
Joined: Tue Jun 24, 2003 7:18 am
Location: Pasig City....

Postby s2kov » Thu Nov 17, 2005 3:28 pm

arnoldc,

I am not sure if i can do the measurement since those test equipment were based here in clark! I maybe help with other things on how to perform such tests in the amp!:)
User avatar
s2kov
Citizen
Citizen
 
Posts: 697
Joined: Thu Sep 18, 2003 3:56 pm
Location: Ang Mo Kio

PreviousNext

Return to Technical Archives

Who is online

Users browsing this forum: No registered users and 3 guests

cron