Article: Taking The RAAL-requisite SR1a and SR1b Headphones to the Pinnacle

[The Computer Audiophile]

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[DuckToller]

Respect & Kudos to @mitchco!

[skatbelt]

Particularly interested in your findings with the dCS Lina Network DAC. Especially as a DAC/Streamer combination. Steve Huff in his review preferred the internal streamer of the Lina vs. going external via the Grimm Audio MU1! dCS has its stuff in order.

[yyz]

The new Tl-1b adapter gets you closer to the very best RAAL SR1a sound, which is with the RAAL VM-1a tube headphone amp. The TL-1b is extremely good and much better than the old RAAl adapter box. I use the TL-1b with a CODA #16 and a modded PeachTree GAN1 (great amp). You can also run very long cable from the amp to the TL-1b and then have a short headphone cable to the phones. My long wire is 25-foot and the headphone cable is 6-foot. All these cables are from RAAL so I know they will work for the intended purpose.

 

I have Mitch's filters but do not use them with the VM-1a. I used to use them with my old adapter box. I will consider them again with the CODA#16 and the PeachTree.

 

A nice DAC/streamer combo with the SR1a or CA-1a is the Lumin X1 DAC/Streamer. I am in the process of upgrading that DAC and streamer to the Playback Designs Dream DAC and PBD Stream-IF streamer. The Stream-IF is the best streamer I have owned. A bit better than the Sonore OpticalRendu and Lumin X1 (both used fibre). Though I am not even using the very best part of the Streamer-IF, the fibre optical Plink. The SPDIF to my Benchmark DAC3B is amazing via the Stream-IF.

[adornoWest]

@mitchco, why is the FR of the SR1a so much different from the SR1b above 3k? My understanding is that these two headphones only have minor differences like the grille and a bit of silver wire.

[adornoWest]

11 hours ago, adornoWest said:

@mitchco, why is the FR of the SR1a so much different from the SR1b above 3k? My understanding is that these two headphones only have minor differences like the grille and a bit of silver wire.

 

Mitch answered here

[mitchco]

12 hours ago, adornoWest said:

@mitchco, why is the FR of the SR1a so much different from the SR1b above 3k? My understanding is that these two headphones only have minor differences like the grille and a bit of silver wire.

 

Just to complete the answer here: The SR1a was measured with open baffle compensation in the circuit, so it is not going to look the same as the raw response I measured without the baffle step in the SR1b. So the attached graph is what is added to the SR1a raw measurement versus without open baffle comp of SR1b. If I “convolve” the SR1b measurement with the open baffle compensation, it comes within 1 dB of the original measurement I made of the SR1a’s two years ago. Says a lot about the quality of engineering and manufacturing of the drivers from Raal. Also, the horizontal scale is different in the two measurement charts. So not exactly an apples-to-apples comparison.

[cfisher]

Chris, thanks so much for writing about Mitch's new filters. It's hard to believe that there was more clarity and detail to wring out of the SR1a. That is undoubtedly the best $50 I have ever spent on my stereo. Thanks, Mitch, for keeping at it!

[The Computer Audiophile]

3 minutes ago, cfisher said:

Chris, thanks so much for writing about Mitch's new filters. It's hard to believe that there was more clarity and detail to wring out of the SR1a. That is undoubtedly the best $50 I have ever spent on my stereo. Thanks, Mitch, for keeping at it!

Isn’t it just crazy? Crazy cool that $50 can get you an upgrade larger than some that cost $50,000. 

[cfisher]

1 minute ago, The Computer Audiophile said:

Isn’t it just crazy? Crazy cool that $50 can get you an upgrade larger than some that cost $50,000. 

 

Without question, it is a component-level upgrade. Being, by profession, on the frugal side of Hi-Fi, I really appreciate it. 

[cfisher]

Chris, you are using the filters in Roon despite the apparent tap bug? Have you compared how the filters sound in Roon and HQPlayer?

[AudioDoctor]

Is it possible to use the filters in HQP along with the DCS Equipment?

[The Computer Audiophile]

12 hours ago, AudioDoctor said:

Is it possible to use the filters in HQP along with the DCS Equipment?

Yes

[The Computer Audiophile]

14 hours ago, cfisher said:

Chris, you are using the filters in Roon despite the apparent tap bug? Have you compared how the filters sound in Roon and HQPlayer?

Yeah, still doing it with Roon despite the bug. I need to get HQP 5 and test. 

[cfisher]

Just now, The Computer Audiophile said:

Yeah, still doing it with Roon despite the bug. I need to get HQP 5 and test. 

 

I just tried with an evaluation version of HQP 5 (still on 3) and it didn't seem like Roon was corrupting the filter in any way. Obviously, don't want to get into a Roon vs. HQP discussion.

[Marcin_gps]

Chris, very nice composition ;)

[mitchco]

Hi @cfisher I agree. I listened to the SR-1b FIR filters in Roon's convolution engine, HQP, JRiver, and HLC. I could not hear a difference,

 

I wanted to take it a bit further and measure Roon's convolution engine to see if the filter is being corrupted in anyway,

The short answer is no.

 

I used REW to generate a "sweep" file that could be played in Roon. A 5 Hz to 22,050 Hz, 44.1 kHz sweep file was played in Roon with no convolution (or any other DSP) applied. I used BlackHole as a virtual loopback driver to route the output of Roon back into REW's input to be measured. This is a "control" test to see that we get the "expected" flat frequency and phase response:

 

 

Sure enough, perfectly flat frequency and phase response.

 

Next I loaded a "test" high resolution headphone FIR filter at 65,536 taps into Roon's convolution engine. I noted that while the sweep was playing Roon displayed the "bug" of 22K taps:

 

 

Of course, it should be displaying 65,536 taps or 66K in Roon speak. And the measurement:

 

 

I made the test headphone filter complex to test any inconsistencies. Lets compare using another convolver.

 

I setup a test where the output of Roon is going into BlackHole, but the output of BlackHole is going into the input of Hang Loose Convolver (HLC) and the output of HLC, using another virtual audio driver called Ground Control, routes the output back into the input of REW. I loaded HLC with a Dirac pulse 65,536 tap FIR filter, which is a "do nothing" FIR filter so we can see that again, as a control test, we get  the expected flat frequency and phase response:

 

 

Sure enough.

 

Now loading the same test FIR filter, we see HLC correctly reporting 65,536 taps:

 

 

And the measurement result:

 

 

Looks the same as Roon's convolver test. Lets make sure by overlaying the results. Frequency response:

 

 

Identical.

 

Phase response:

 

 

Identical.

 

Conclusion: While Roon may have a convolution bug of some sort, it is definitely not affecting or corrupting the frequency or phase response of these high resolution headphone FIR filters.

 

Back to listening to music.

 

[The Computer Audiophile]

1 hour ago, mitchco said:

Hi @cfisher I agree. I listened to the SR-1b FIR filters in Roon's convolution engine, HQP, JRiver, and HLC. I could not hear a difference,

 

I wanted to take it a bit further and measure Roon's convolution engine to see if the filter is being corrupted in anyway,

The short answer is no.

 

I used REW to generate a "sweep" file that could be played in Roon. A 5 Hz to 22,050 Hz, 44.1 kHz sweep file was played in Roon with no convolution (or any other DSP) applied. I used BlackHole as a virtual loopback driver to route the output of Roon back into REW's input to be measured. This is a "control" test to see that we get the "expected" flat frequency and phase response:

 

 

Sure enough, perfectly flat frequency and phase response.

 

Next I loaded a "test" high resolution headphone FIR filter at 65,536 taps into Roon's convolution engine. I noted that while the sweep was playing Roon displayed the "bug" of 22K taps:

 

 

Of course, it should be displaying 65,536 taps or 66K in Roon speak. And the measurement:

 

 

I made the test headphone filter complex to test any inconsistencies. Lets compare using another convolver.

 

I setup a test where the output of Roon is going into BlackHole, but the output of BlackHole is going into the input of Hang Loose Convolver (HLC) and the output of HLC, using another virtual audio driver called Ground Control, routes the output back into the input of REW. I loaded HLC with a Dirac pulse 65,536 tap FIR filter, which is a "do nothing" FIR filter so we can see that again, as a control test, we get  the expected flat frequency and phase response:

 

 

Sure enough.

 

Now loading the same test FIR filter, we see HLC correctly reporting 65,536 taps:

 

 

And the measurement result:

 

 

Looks the same as Roon's convolver test. Lets make sure by overlaying the results. Frequency response:

 

 

Identical.

 

Phase response:

 

 

Identical.

 

Conclusion: While Roon may have a convolution bug of some sort, it is definitely not affecting or corrupting the frequency or phase response of these high resolution headphone FIR filters.

 

Back to listening to music.

 

I’m glad my ears were right for once :~)

[cfisher]

@mitchco that is amazing. Thanks for taking the time to assuage our audio nervosa.

[Jacob]

Hi all.
I have a RAAL Sr-1a with Jotenhiem amp for sale .... PM if interested.
+972-54-9333389

[cfisher]

Jacob, hope you are ok. I'm catatonically refreshing my Haaretz feed here in the US. What are you replacing the RAALs with?