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Author Topic: stratoKOSSter (KSC75 mod) Frequency Response and CSD Waterfall Plots  (Read 12387 times)

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stratocaster

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StratoKOSSter V2
« Reply #50 on: August 21, 2012, 09:01:29 AM »
StratoKOSSter V2

I have been using Koss KSC-35 drivers instead of KSC-75 drivers for the V2. While the midrange and lower frequencies remain pretty much as they were, the higher frequencies are a tad smoother and cleaner sounding than compared with the 75 drivers.

As for the damping, the foam should not fill the whole cup. If it presses against the drivers, the Stratos sound a little thin. When there is a kind of air cushion between drivers and foam, they perform best with the most balanced sound.
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Solderdude

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Re: stratoKOSSter (KSC75 mod) Frequency Response and CSD Waterfall Plots
« Reply #51 on: July 05, 2014, 08:47:02 PM »
Have measured some other stratocasters...



For those interested in the results they can be found here:
http://www.mediafire.com/view/6axk75y6svpu1x7/Stratocaster_woodies.pdf

It should be noted that they aren't finished 'products' and have been measured to see where they need more improvements.
For headphone tuning exclusively by ear the results are already quite good.
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spoony

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Re: stratoKOSSter (KSC75 mod) Frequency Response and CSD Waterfall Plots
« Reply #52 on: July 06, 2014, 01:27:47 AM »
Aside from the channel imbalance (fixable, I reckon), the T50RP + Alpha pads has terrific performance with almost no shelving, very impressive!

May I ask what kind of foam/felt sits in front of the Fostex drivers?, it seems to tame the 10 KHz peak to a good degree.
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Solderdude

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Re: stratoKOSSter (KSC75 mod) Frequency Response and CSD Waterfall Plots
« Reply #53 on: July 06, 2014, 08:25:54 AM »
In this particular case the secret ingredient isn't the foam in front of the driver but rather the damping behind it in conjunction with Dan's Alpha pads.



With and without foam...

A clue is found in the plot below.
I mounted an Alpha pad on my modified T50RP (just some damping in the cups and white medical felt in front and rear of the driver)



As you can see the Alpha pads are filling in the hole and remove the peak (but add that sharp dip)
Alpha pads are compared to SRH-940 velour pads in this case.

I can feel the next question popping up... How do the 940 pads compare to HM5 pads ?



there you are  :D
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stratocaster

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Re: stratoKOSSter (KSC75 mod) Frequency Response and CSD Waterfall Plots
« Reply #54 on: July 06, 2014, 01:54:35 PM »
I guess it is more than just the damping and the alpha pads, there are many variables that create the sound. The ebony T50RPs are different from the Kerelian birch T50s in so far as the internal cup dimensions are different (the ebony cups are significantly deeper), as well as the white damping paper behind the driver has been removed from the ebony drivers and replaced by T50RP damping paper. I tried the alpha pads and the same damping in the Karelian cups, yet the sound was significantly worse than with the ebony set.
There may be driver variances, damping material/amount differences, cup dimensions, cup materials, pads .... It is combination of all that and maybe a lot more that creates the result.  There is simply no standard modding approach, results and suggestions by others may help you or not. You have to work on each set of headphones/drivers more or less differently and trust your ears and/or measurements.
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Solderdude

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Re: stratoKOSSter (KSC75 mod) Frequency Response and CSD Waterfall Plots
« Reply #55 on: July 06, 2014, 03:39:07 PM »
Quote from: stratocaster on July 06, 2014, 01:54:35 PM
There is simply no standard modding approach, results and suggestions by others may help you or not. You have to work on each set of headphones/drivers more or less differently and trust your ears and/or measurements.

Judging from the results on the Alpha padded T50RP it appears you can get great results with mods even without the guidance of measurements.
These do make life of a modder easier when you are aiming for balance and flat frequency response.
Given that these mods were all mechanical/acoustical the results are excellent.

but to get back on topic:
Quote from: stratocaster on July 06, 2014, 01:54:35 PM
I have been using Koss KSC-35 drivers instead of KSC-75 drivers for the V2. While the midrange and lower frequencies remain pretty much as they were, the higher frequencies are a tad smoother and cleaner sounding than compared with the 75 drivers.
That's what my measurements (and ears) tell me as well.

green = KSC75 (old)
purple = KSC35 (old)
blue = PortaPro (recent)
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spoony

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Re: stratoKOSSter (KSC75 mod) Frequency Response and CSD Waterfall Plots
« Reply #56 on: July 06, 2014, 06:03:28 PM »
I think stratocaster reverted back to the KSC75 drivers in his latest builds.
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