Anyone knows the frequency response of the Stax L300 Limited edition?

[Florin Andrei]

- I assume you bought the L700 pads? Do you recommend them?

I have. I'm not sure.

Honestly, the original pads are not too bad. There is the question of the different measurements in the bass response with the different pads, but I can't speak with any confidence since I'm only testing with the L700 pads.

- What do you use for eq? I have ADI-2 DAC I could most likely use.

Equalizer APO. You can see some of the filters, and the whole frequency response curve, here:

For the corrections above 1 kHz, I use the lab measurements by oratory1990.

https://www.reddit.com/r/oratory1990/wiki/index

Below 100 Hz I am also guided by his measurements, but I deviate from his recommendations. My goal was to make Stax sound like Audeze below 100 Hz, and I've done it.

They have a slope of 12 dB / octave, descending into the low bass. With the original pads the slope begins at 74 Hz. With the L700 pads, the slope begins in the upper 40s.

The compensation for all that is the high-shelf filter with a 12 dB / octave slope in my screenshot - the one centered on 30 Hz. This works for the L700 pads. With the original pads you may have to push that frequency higher, but I have not tried that.

The first filter, high-pass at 10 Hz, is just there to avoid stressing the membrane too much if there's a lot of infrasound in the signal.

If you're only interested in fixing bass, then all you need is the stuff below 100 Hz.

- I have two amps at the moment for testing, the SRM-252S and SRM-353X limited. I have done a couple of tests with both and don't seem to hear any differences in sound. Which one would you recommend? Regarding listening volume, I seem to use the 252S between 9-10 o'clock levels, so that little thing seems to have enough power for me.

I've spent an afternoon comparing the 353X and the D10 and I could not hear any difference.

I am using the 353X now, but that's just because it has more power, and I need that extra power due to the very deep (20 dB) correction I've applied for bass.

 

[flipflop]

The first filter, high-pass at 10 Hz, is just there to avoid stressing the membrane too much if there's a lot of infrasound in the signal.

If you're only interested in fixing bass, then all you need is the stuff below 100 Hz.

I would advise against boosting anything below 20 Hz. L300 approach 100% THD @ 10 Hz @ 100 SPL: https://www.rtings.com/headphones/1-2/graph#747/2085

 

[Florin Andrei]

I would advise against boosting anything below 20 Hz. L300 approach 100% THD @ 10 Hz @ 100 SPL: https://www.rtings.com/headphones/1-2/graph#747/2085

This is a major point of disagreement between rtings.com and oratory1990.

Per the latter, distortion remains very low even at high levels at low frequencies. He's also mentioned it's hard to get good measurements in this regard, it requires a room that's sealed against external noise (which would be picked up by instruments as "distortion"), and that's really hard to do in the low frequencies. His initial measurements were wrong for this reason and he had to repeat them. The second round he was much more confident about, and he expressed surprise at the very low distortion numbers that popped on his instruments.

He works at a company that makes solid state transducers, I would imagine their labs are somewhat better than some random review site online.

Also, I do believe I have quite a bit of experience hearing overdriven speakers and headphones, based on previous experience and having many of these destroyed in my younger and more foolish years. I do not hear a single shred of distortion in my L300LTD even with the correction applied while listening at high volume (cathedral organ music playing some massive Earth-shaking instruments). I would definitely hear it long before it approaches 100%. But this is subjective so take it for what it's worth.

Super-happy about the deep correction I need to apply? Is this how things ought to be in an ideal world? No and no. But it does the job, and I do not perceive any downsides.

Give it a try, I think the results speak for themselves.

 

[flipflop]

Per the latter, distortion remains very low even at high levels at low frequencies. [...]. His initial measurements were wrong for this reason and he had to repeat them. The second round he was much more confident about, and he expressed surprise at the very low distortion numbers that popped on his instruments.

I wasn't aware oratory measured THD. Where did you get this information from?

Also, I do believe I have quite a bit of experience hearing overdriven speakers and headphones, based on previous experience and having many of these destroyed in my younger and more foolish years. I do not hear a single shred of distortion in my L300LTD even with the correction applied while listening at high volume (cathedral organ music playing some massive Earth-shaking instruments). I would definitely hear it long before it approaches 100%.

I'm mainly concerned about the well-being of the drivers and not so much audible issues.

 

[THW]

This is a major point of disagreement between rtings.com and oratory1990.

Per the latter, distortion remains very low even at high levels at low frequencies. He's also mentioned it's hard to get good measurements in this regard, it requires a room that's sealed against external noise (which would be picked up by instruments as "distortion"), and that's really hard to do in the low frequencies. His initial measurements were wrong for this reason and he had to repeat them. The second round he was much more confident about, and he expressed surprise at the very low distortion numbers that popped on his instruments.

Did he get any HD 600 THD measurements, per chance?

I may actually play with EQ for it some time if the THD is low enough at the low frequencies, while it is great overall out-of-the-box for me, I feel like it can do with a wee bit more sub-bass

 

[Florin Andrei]

I wasn't aware oratory measured THD. Where did you get this information from?

He was sending me real-time updates via Reddit PMs as he was measuring my cans.

I am going to post here a quote from one of his PMs, I think it's okay to do so without asking for permission, it's just lab stuff.

---
Right so I just measured it with an EQ to flatten the response below 300 Hz or so. Required ~22 dB of boost at 10 kHz. [pretty sure he meant 10 Hz]
I measured up to 94 dB @ 1 kHz, but saw no noteworthy distortion down to 20 Hz.
What I saw I assume was caused by the amplifier, not by the headphone (due to its dynamic behaviour). I assume what I measured was in fact crossover distortion (of the amplifier).
The earlier THD measurements must then have been showing the background noise of the noisier room that I used. I got the quiet lab today and, as I said, saw no distortion of the headphone (<0,1%).
---

I'm mainly concerned about the well-being of the drivers and not so much audible issues.

I guess I'll find out.

My younger son is playing some very explode-y video game every day, using the Stax with the corrections applied, and so far nothing bad has happened. I don't really expect problems, TBH.

Did he get any HD 600 THD measurements, per chance?

No idea.

 

[flipflop]

Did he get any HD 600 THD measurements, per chance?

I may actually play with EQ for it some time if the THD is low enough at the low frequencies, while it is great overall out-of-the-box for me, I feel like it can do with a wee bit more sub-bass

HD 600 THD measurements aren't exactly scarce:
https://www.innerfidelity.com/images/SennheiserHD600.pdf
https://www.0db.co.kr/files/attach/images/179/534/e46d7254cc18598190d90904f9906c85.png
https://www.rtings.com/headphones/1-2/graph#325/2085
https://lh3.googleusercontent.com/-...s1600/Sennheiser%2520HD600%2520-%2520thdl.png
https://lh3.googleusercontent.com/-...s1600/Sennheiser%2520HD600%2520-%2520thdr.png

 

[THW]

No idea.

Well shit, that sucks.

As for Rtings.com measurements... might be a bit off topic but their HD 800S measurements don’t seem particularly accurate, at least based on cursory cross-referencing

 

[THW]

HD 600 THD measurements aren't exactly scarce:
https://www.innerfidelity.com/images/SennheiserHD600.pdf
https://www.0db.co.kr/files/attach/images/179/534/e46d7254cc18598190d90904f9906c85.png
https://www.rtings.com/headphones/1-2/graph#325/2085
https://lh3.googleusercontent.com/-QIILEryT5UE/Vwvfbal0rfI/AAAAAAAADZ8/xFFx74r3c9Y/s1600/Sennheiser%2520HD600%2520-%2520thdl.png
https://lh3.googleusercontent.com/-uOD7cvma9dQ/Vwvfb_QUtAI/AAAAAAAADaA/e15_lwMnRqY/s1600/Sennheiser%2520HD600%2520-%2520thdr.png

Results seem fairly consistent unless I’m reading this wrongly, 2-5% THD is probably not completely ideal but not a total disaster either, at low frequencies our hearing sensitivity isn’t so good so I don’t think I should expect any serious problems with EQ should I attempt to apply EQ correction in that region

 

[soundwave76]

I have a 5 band eq in my ADI-2 DAC. Any advice on how I should configure those for best result? (options for each band are: Gain, Freq, Q-factor and fiter mode for bands 1 and 5; Peak mode, Shelf mode or High Pass / High Cut)

Thanks in advance for help!

 

[flipflop]

I have a 5 band eq in my ADI-2 DAC. Any advice on how I should configure those for best result? (options for each band are: Gain, Freq, Q-factor and fiter mode for bands 1 and 5; Peak mode, Shelf mode or High Pass / High Cut)

Thanks in advance for help!

oratory1990’s EQ preset uses 8 bands. The result looks like this:

I tried to replicate it using only 5 bands. Here is what it looks like:

Bands
Filter 1: Low shelf, 45 Hz, Gain 7.4 dB
Filter 2: Peak, 470 Hz, Gain 1.4 dB, Q 1.5
Filter 3: Peak, 1300 Hz, Gain -6.3 dB, Q 2
Filter 4: Peak, 3100 Hz, Gain 4.5 dB, Q 0.7
Filter 5: Peak, 5800 Hz, Gain -4.5 dB, Q 4

Preamp: -7.5 dB

 

[soundwave76]

THANK YOU! I will try these soon and report back how it sounds

 

[soundwave76]

All right... I set the ADI-2 eq to these parameters and I must say it sounds a lot better. The first reaction was that the sound is not 'hollow' anymore, especially on guitar tracks, like with Mark Knopfler / The Trawlerman's Song. Another observation was with Toto / Spanish Steps, where the bass is a LOT more deeper and punchier - maybe even a bit too much. Then again that song has an over emphasized bass imo...

Overall, thanks a lot @flipflop @FlorinM! Eq seems to do miracles also to these headp... correction, ear speakers

P.S. Here's a pic of the eq curve on ADI-2

 

[Florin Andrei]

The first reaction was that the sound is not 'hollow' anymore

There's a tall, broad hill around 1.2 ... 1.3k that gets squished by these presets. If uncorrected, it adds a "1930s telephone line" character to the sound which probably shouldn't be there. OTOH it's responsible for the supernatural vividness of voice reproduction on these phones.

I'm still not convinced that hill should be pushed down that hard (6 ... 7 dB) - voices are then shoved into the background. But I like the crisp sound of the EQed cans too. Decisions, decisions...

The bass should be raised far, far more than that. The recommendations in oratory1990's PDF do not achieve linear response below 100 Hz; he's a bit conservative in his recommendations when corrections are very deep, which makes sense.

If you use the L700 pads, it should be a low shelf filter, centered around 30 Hz, with a slope of 12 dB / octave (or Q factor of 0.7 if I'm not mistaken), with 20 dB of gain. That makes these cans sound like the LCD-2 below 100 Hz. There's no other way to make them work with ultra-deep bass drops in some electronica genres, or with the lowest notes played by big cathedral organs and the like.

With the original pads the center frequency of the low shelf should be raised to near 55 Hz or so (I have not tried this). Some experimentation would be needed anyway. It would help a lot if you could get your hands on a pair of big planars with linear bass response, as a reference.

Of course, that would push down the rest of the signal a lot. Hopefully your estat amp has a high enough power ceiling. I've switched from the D10 back to the 353X for this reason.

---

Alternatively, for bass you could use a high shelf with negative gain (same amount, just negative), and that would eliminate the need for a preamp filter to avoid clipping. If you look at the settings recommended by flipflop, the preamp matches the gain of the bass low shelf almost exactly. Do a high shelf instead, with negative gain, and the preamp can be removed.

Low shelf with positive gain and high shelf with negative gain are the same thing, just reflected in a horizontal mirror (flipped along the horizontal axis).

---

I'm a little jealous of y'all ADI-2 owners. That's a nifty toy that packs a lot of features. Take your corrections with your DAC, wherever it goes, that's neat.

 

[soundwave76]

Hey @flipflop , I just noticed the 'preamp: -7.5 dB' value which I missed when setting up the eq. What does this mean in my case? I can set the volume of ADI-2 line out to that value, but this is probably not what that means...?

 

[flipflop]

Hey @flipflop , I just noticed the 'preamp: -7.5 dB' value which I missed when setting up the eq. What does this mean in my case? I can set the volume of ADI-2 line out to that value, but this is probably not what that means...?

The preamp setting is to avoid clipping because the highest boost of the EQ is right above 7 dB. You can lower anything, regardless of the name, that prevents the output from going over 0 dBFS and it should fix the problem.

 

[soundwave76]

Hmm, so lowering the ADI-2 line out volume would thus do the trick? I will try that...

 

[Florin Andrei]

I'm not super familiar with the ADI-2, but perhaps it adjusts gain automatically?

Any EQ worth anything should do one of two things:
- adjust gain to compensate for overdrive
- clearly indicate you're overdriving the digital bus with your filters, and even tell you the amount in dB (this is what Equalizer APO does) so you can add a preamp filter in the chain and reduce the peak to 0 dB

 

[soundwave76]

^ this is a good point, ADI-2 is quite smart so it just might do that. I need to read the manual and/or ask this in the RME Forum. I am now using it with -7 dB volume just to see if I notice any differences. The SRM-252S amp is now at 10 o'clock volume, so seems to have enough power.

 

[soundwave76]

ADI-2 seems to indeed be smart about EQ and clipping. Seems I don't need to limit the line out volume. From the manual...

The ADI-2 DAC has an internal headroom of 24 dB. Extreme boosts with overlapping filters could cause an internal overload. Such an overload will be visible as it is displayed by the level meter below the EQ, as well as the channel’s level meter. Reducing the output volume will prevent any clipping as long as the headroom of 24 dB is not exceeded. In real-world operation that is always the case, the ADI-2 DAC will not distort internally.