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Measurable frequency response?

post #1 of 7
Thread Starter 
Are there any components/cables that cause a measurable, consistent change in the frequency response of a speaker/headphone? For example, will switching to a tube amp from solid state make some of the frequencies less/more pronounced?

I can't remember ever seeing a frequency response graph for anything other than a speaker or headphone. If amps, sources, cables etc make any real difference in the sound, then I would certainly like to see some frequency response graphs where two components were the only variable and the change in frequency response was illustrated to demonstrate differences.

I'm aware that components transmit frequencies; they don't respond to frequencies. But according to most audiophiles, components make a difference in the sound so the frequencies sent to the headphones/speakers should change in a measurable fashion.
post #2 of 7
CD drives : no difference
DACs :

Solid state oversampling CD player DACs : flat within 0.5 dB in bass and medium. Treble attenuation depends on the DAC.

Examples :

Yamaha CDX-860 CD player to Sony DTC55ES DAT deck :



Zoom in the highest frequencies :


Sony DTC55ES DAT deck to Marian Marc 2 soundcard :



Basic computer soundcards : can be more erratic.

Example : Soundblaster 64 PCI to Sony DTC55ES DAT deck :



Non-oversampling DACs have a treble roll-off :



See discussion here : http://www.head-fi.org/forums/f133/u...9/#post5263769

Tube DACs may also have some trouble in their frequency response. I have no info about this.

Amplifiers

Quite flat too, but less than CD players.

An interesting example can be seen in http://www.soundandvisionmag.com/ass...rInterface.pdf

Figure 2 : tube amp vs transistor amp on a difficult load. The transistor amp stays within +0 / -1 dB, while the tube amp is within +1 / -2 dB.

Figure 3 : same amplifiers on an easy load. They are both within 0 / +1 dB.

A different example : headphone outputs

White / green : Arcam Diva A85 integrated amplifier with headphone output
Blue / pink : Marian Marc 2 soundcard output

Flat curves : unplugged
Unflat curves : with Sennheiser HD600

post #3 of 7
Interconnects

Here are a bunch of frequency response measurments of interconnects. They were done with the Yamaha cdx-860 CD player as a source, and the Sony DTC55ES deck as a measurment device.

The only significant difference in frequency response is a treble roll off of 0.02 dB at 20 kHz, introduced by a 5 meters standard extention cord. All other interconnects have a completely flat response within +/- 0.02 dB, silver-plated or not.

Original article (in French) : homecinema-fr.com • Afficher le sujet - Résultats du test en aveugle - câbles de modulation

The standard interconnects were measured three times : twice in a row first, then once more after all other measurment had been performed, in order to check for consistency in the measurment chain.

Then all measurments done with other interconnects than the standard ones were analyzed in comparison with the standard ones. The frequency responses below are the difference with the standard interconnect. The treble spikes should not be taken into account because the signal was dropping into noise at these frequencies, and the spikes might just be random differences in noise.

Difference between the first and last measurment with standard interconnects :



Any similar difference in other comparisons must be discarded as not being caused by the interconnects, since here, a given interconnect is compared to itself.

Difference between standard and...

Home-made interconnect made of cheap ACR cable :



Audioquest Diamondback (137 € ) :



DIY by Ogobert :



Another DIY by Ogobert, unshielded :



Home-made RG 179 :



Standard interconnect itself, plus a five meters-long female-male standard extention :



Taralabs RCS Reference generation 2 (560 € ) :

post #4 of 7
Speaker cables

The response of speaker cables depends on the output impedance of the amplifier and on the input impedance of the speakers.

I measured the difference between the spectral content of the signal at the output of the amplifier, thus at the input of the cable, and at the input of the speaker, thus at the output of the cable.
Amplifier : Arcam Diva A85
Speaker : Dynaudio Gemini, "Maison du Haut-Parleur" version. Nominal impedance : 4 Ohms.

QED speaker cable (unknown model, probably Qudos), 4.5 meters. Result : up to -0.2 dB above 8 kHz

Same cable, but 6.5 meters long. Result : up to -0.3 dB above 8 kHz

Acome A2 (Shielded monstrous 12mm2 solid core copper ! ), 4 meters long. Result :
up to +0.15 dB between 3 and 8 kHz, and up to -0.2 dB above 8 kHz.

Complete report : http://www.hydrogenaudio.org/forums/...0&#entry135916

Another recording was made by Lucpes, with extremely low impedance speakers : Infinity Reference standard II.
Comparison of spectral content between 2xCAT5 cables per polarity (4x8 wires/speaker) versus thicker 'lamp' cord, 3 meters long. Result :
+2 dB above 10 kHz for the lamp cord !

Original post (Spectral analysis three posts below) : http://www.hydrogenaudio.org/forums/...1&#entry148461
post #5 of 7
post #6 of 7

I wish I had read this stuff two weeks ago.....

I wish I had read this stuff two weeks ago.....

Quote:
Originally Posted by Pio2001 View Post
Interconnects

Here are a bunch of frequency response measurments of interconnects. They were done with the Yamaha cdx-860 CD player as a source, and the Sony DTC55ES deck as a measurment device.

The only significant difference in frequency response is a treble roll off of 0.02 dB at 20 kHz, introduced by a 5 meters standard extention cord. All other interconnects have a completely flat response within +/- 0.02 dB, silver-plated or not.

Original article (in French) : homecinema-fr.com • Afficher le sujet - Résultats du test en aveugle - câbles de modulation

The standard interconnects were measured three times : twice in a row first, then once more after all other measurment had been performed, in order to check for consistency in the measurment chain.

Then all measurments done with other interconnects than the standard ones were analyzed in comparison with the standard ones. The frequency responses below are the difference with the standard interconnect. The treble spikes should not be taken into account because the signal was dropping into noise at these frequencies, and the spikes might just be random differences in noise.

Difference between the first and last measurment with standard interconnects :



Any similar difference in other comparisons must be discarded as not being caused by the interconnects, since here, a given interconnect is compared to itself.

Difference between standard and...

Home-made interconnect made of cheap ACR cable :



Audioquest Diamondback (137 € ) :



DIY by Ogobert :



Another DIY by Ogobert, unshielded :



Home-made RG 179 :



Standard interconnect itself, plus a five meters-long female-male standard extention :



Taralabs RCS Reference generation 2 (560 € ) :

post #7 of 7
Here is a simulation of the frequency response of a 6x4x3 meters closed room with rigid walls, little damped, for a perfectly linear source from 0 Hz.

Taken from Earl Geddes book (quoted from Le punch, le slam, la frappe, le foot-tapping, toussa... - Page 3 ).

We can see variations in the +/- 10 db range, and they do not disappear at medium frequencies.
LL
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