Raal Ribbon Headphones - SRH1A
Jul 9, 2019 at 7:15 AM Post #1,351 of 7,750
A cautionary tale for those using an AHB2 who may be thinking about adding an LA4 or HPA4 - I had been looking for a preamp to move away from digital volume control and to incorporate my turntable back into my system, and naturally tried a Benchmark preamp, the LA4. Unfortunately in my system I’m noticing a big drop off in sound quality and musical enjoyment with the LA4 as opposed to digital volume control. The LA4 introduced a good deal of brightness and I notice how much smoother music sounds with digital volume control. I just bought Benchmark’s xlr cables to see if these might help resolve the issue - don’t have high hopes but it’s worth a shot before I try to return or sell.

If anyone knows of a high quality solution where digital volume control can be effected through a discrete device with a volume knob and remote please let me know, I have searched but not been able to find one.
 
Jul 9, 2019 at 10:05 AM Post #1,352 of 7,750
A cautionary tale for those using an AHB2 who may be thinking about adding an LA4 or HPA4
Thanks for reporting your findings!

That‘s precisely what I‘m planning to do as well - SR1a is going to arrive here tomorrow, AHB2 on Friday. I currently have a Schiit Freya S and a single Vidar here waiting, so will try the AHB2 both with the Freya S and with a purely passive preamp which I have around (can‘t go direct from my DAC as the Meitner MA1 V2 doesn‘t have a volume control), until the HPA4 arrives later that month when it becomes available.

I was tempted to instantly say that your LA4+AHB2 combo sounds brighter because the LA4 removes all the deterioration the DAC‘s digital volume control caused, but that‘s certainly besides the point. I assume you have set the Sensitivity switch on the AHB2 to the Low setting at 22 dBu when connecting in the LA4? Can only imagine that the difference in output level (the DAC likely has some 4Vrms while the LA4 outputs 20Vrms) makes some difference...

Will have to wait some more weeks unfortunately until my HPA4 arrives and I can give more meaningful input and correlating observations.
 
Jul 9, 2019 at 10:11 AM Post #1,353 of 7,750
Thanks for reporting your findings!

I was tempted to instantly say that your LA4+AHB2 combo sounds brighter because the LA4 removes all the deterioration the DAC‘s digital volume control caused, but that‘s certainly besides the point. I assume you have set the Sensitivity switch on the AHB2 to the Low setting at 22 dBu when connecting in the LA4? Can only imagine that the difference in output level (the DAC likely has some 4Vrms while the LA4 outputs 20Vrms) makes some difference...

Indeed my experience with some DACs is digital volume control can cause a smoother/softer sound. So depending on one's perspective that can be a good thing or not. That said I did not try the LA/HPA4 as a preamp in my system. But I will try one eventually.
 
Jul 9, 2019 at 11:35 AM Post #1,355 of 7,750
I was tempted to instantly say that your LA4+AHB2 combo sounds brighter because the LA4 removes all the deterioration the DAC‘s digital volume control caused, but that‘s certainly besides the point. I assume you have set the Sensitivity switch on the AHB2 to the Low setting at 22 dBu when connecting in the LA4? Can only imagine that the difference in output level (the DAC likely has some 4Vrms while the LA4 outputs 20Vrms) makes some difference..

I am actually using digital volume control through Roon with “Device” selected - not sure if the actual modulation is being done in my ISO Regen, Singxer SU6, or Denafrips Terminator, which does not have built-in volume control.

The interesting thing is that when I select a high dynamic range album that lets me compare (1) dac direct to amp with fixed volume (no digital volume control used) versus (2) dac to preamp with 0 gain, I still get improved sound quality going direct compared to using a preamp. In fact my perceptions of the differences are the same as when I am comparing digital volume control in a direct setup vs a preamp. This tells me that it’s not the digital volume control which is introducing smoothness, it’s the preamp which is introducing harshness. Perhaps the only other explanation could be differences in impedances however I am within the recommended ratios online for connecting a dac directly to an amp - I think I remember no less than 100:1.

Although there appears to be healthy debate online regarding digital volume control vs preamps, with more agreement toward the preamp side, in my rig and with my ears digital is winning out big time.

Yes, am using 22dbu in AHB2 when connected to the LA4 preamp but notice the difference regardless of amp setting.
 
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Jul 9, 2019 at 1:09 PM Post #1,356 of 7,750
I am actually using digital volume control through Roon with “Device” selected - not sure if the actual modulation is being done in my ISO Regen, Singxer SU6, or Denafrips Terminator, which does not have built-in volume control.

The interesting thing is that when I select a high dynamic range album that lets me compare (1) dac direct to amp with fixed volume (no digital volume control used) versus (2) dac to preamp with 0 gain, I still get improved sound quality going direct compared to using a preamp. In fact my perceptions of the differences are the same as when I am comparing digital volume control in a direct setup vs a preamp. This tells me that it’s not the digital volume control which is introducing smoothness, it’s the preamp which is introducing harshness. Perhaps the only other explanation could be differences in impedances however I am within the recommended ratios online for connecting a dac directly to an amp - I think I remember no less than 100:1.

Although there appears to be healthy debate online regarding digital volume control vs preamps, with more agreement toward the preamp side, in my rig and with my ears digital is winning out big time.

Yes, am using 22dbu in AHB2 when connected to the LA4 preamp but notice the difference regardless of amp setting.
In my speaker system I was running a Bricasti M1SE to my Bricasti M28 monoblocks before upgrading the the Bircasti M21. The M1SE has a digital volume control and Bricasti recommended to have the volume always between 0 to -16db. if it goes below -16db since the volume control is done in the digital domain they say it starts affecting resolution because it starts eliminating bits.
I adjusted the balanced output of the M1SE to always keep the volume within that range and found out the the sound was more dynamic and with better resolution going direct than using am analog pre-amp in the middle.
 
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Jul 9, 2019 at 1:20 PM Post #1,357 of 7,750
A cautionary tale for those using an AHB2 who may be thinking about adding an LA4 or HPA4 - I had been looking for a preamp to move away from digital volume control and to incorporate my turntable back into my system, and naturally tried a Benchmark preamp, the LA4. Unfortunately in my system I’m noticing a big drop off in sound quality and musical enjoyment with the LA4 as opposed to digital volume control. The LA4 introduced a good deal of brightness and I notice how much smoother music sounds with digital volume control. I just bought Benchmark’s xlr cables to see if these might help resolve the issue - don’t have high hopes but it’s worth a shot before I try to return or sell.

If anyone knows of a high quality solution where digital volume control can be effected through a discrete device with a volume knob and remote please let me know, I have searched but not been able to find one.

What's the input voltage on the LA4? Preamps can be sensitive to input loads. I liked the LA4 when I tried it as part of an AHB2 stack - but YMMV, of course.
 
Jul 9, 2019 at 6:02 PM Post #1,358 of 7,750
What's the input voltage on the LA4? Preamps can be sensitive to input loads. I liked the LA4 when I tried it as part of an AHB2 stack - but YMMV, of course.

According to their manual, input voltage at unity gain is +24 dbu via balanced so about 12vrms. However my Terminator xlr output is 4 volts; maybe that’s where the issue is? I’ll see if unbalanced is better; LA4’s input is 2vrms.
 
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Jul 10, 2019 at 5:31 AM Post #1,359 of 7,750
I just came from the Abyss booth, where I had decided that the 1266 TC will be my next upgrade, when I ran into the Heddphone stand.
I was impressed enough by the prototype, that I decided to postpone my Abyss 1266 TC purchase and instead am planning now to wait until the last quarter of 2019, when these HP will become available.
If they hold their sonic promises, it could save me several thousand dollars, when compared to the price of the Abyss.
Please PM me when you have fully auditioned the Hedd and compared it to the TC, Susvara and SR1a. Thanks
 
Jul 10, 2019 at 6:26 AM Post #1,361 of 7,750
Has anyone yet with a Susvara, PHI TC, SR1a experience heard the new HEDDPhone by the German company using a ribbon driver. Now that would be a very interesting comparison.

has been said and confirmed by the CEO of Raal Aleksander that the Heddphone does not have the sr1a driver,
no electrical specifications in common, ohm, sensitivity or other, the sr1a without its box does not work and needs 100 watts!
 
Jul 10, 2019 at 8:12 AM Post #1,363 of 7,750
A special thanks to @sean888 of SLT Technologies for making sure that i recieved the version with all the problems ironed out. It really was worth the wait.

@Aleksandar R. is there a revision history available to review somewhere?
 
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Jul 10, 2019 at 8:21 AM Post #1,364 of 7,750
Finally recieved my SR1a yesterday. The soud, driven by my Vidar monoblocks, is just sublime. You really have to try it to belive it.

A special thanks to @sean888 of SLT Technologies for answering my newbie questions. Really learned alot through our conversations.
Do need an interface box between SR1a and the power amp? Can you elaborate on what “problems” were ironed out? Also, do you know anything about the HEDDphone AMT headphones by a company called HEDD and how they compare to the SR1a and other planars?
So many new TOTL cans to try Susvara, PHI TC, SR1a and now HEDD.
 
Jul 10, 2019 at 8:29 AM Post #1,365 of 7,750
Sorry for the error in my earlier remarks about "problems", which was not what I meant. I was actually waiting for the version with the nice RAAL-requisite decals on the Pelican case + the softer headphone cables, which I just received. Just my poor English, apologies, my bad!
 

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