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Confusing SE and balanced features of Topping A50s vs new L50

JanesJr1

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I am confused by the balanced and SE features of Topping's A50s and L50 headphone amps. I'm trying to pick one or the other to use with both very-low-impedance headphones and active speakers with balanced inputs. I'm thinking of Topping b/c of high current and power for low impedance HP, and price/value.

The L50 has a SE amplifier, according to Topping, and passes through pre-amp signals from DAC directly to external active speakers or amplifier (i.e. no pre-amp function). The A50s, unlike the L50, has a balanced amp, which also controls a pre-amp function, and has SE inputs. So here are my questions:

1. The L50 has a SE amplifier, yet has an XLR headphone output circuit. Does that mean that there is no doubling of the power to the headphones, but rather just a mechanism to pre-empt ground loops?

2. The L50 has a pass-through line-in/line-out for non-headphone outputs. But it also accepts balanced inputs. Does that mean that balanced inputs are no longer balanced when passed to an external device (non-headphone)? Or (showing my technical naivete, perhaps) is the pass-through somehow transparent enough to maintain balance from external input to amp output?

3. Since the A50s has RCA output connectors for non-headphone devices, there must be no way to use the A50s in balanced mode with active speakers, despite the balanced amplifier circuit ... am I right? (Topping doesn't explicitly say anywhere that balanced mode applies only to headphones with the A50s.)

4. With the L50, due to the pass-through, I assume the volume knob doesn't work with the pass-through signal, as it would with the headphone output. I guess that means that to control a powered speaker with, say, a PC's streaming input signal, the volume control for the whole system could only be the PC's volume control or an external DAC, if there is one?

And I assume the A50s, by contrast, could be the volume control for the whole system. (Or the DAC could if it has a volume knob.)

5. I know this has to be a hokey thought, but there's no way to use a 4.4mm balanced output to drive an active speaker in balanced mode, is there?

6. Topping's literature doesn't explain this all very well, except to hint that the L50's pass-through feature makes it somehow advantaged to use with active speakers ... Although elsewhere, Topping says the A50s (with SE outputs to active speakers but with a pre-amp function) is just dandy to use with active speakers. What's the deciding factor?
 

mugbot

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Reviews:

These should provide guidance on the max power output into low impedance headphones at least. Looks to me like the A50s has it by a hair, but it's likely both would be more than sufficient. Don't get too caught up in balanced vs single ended. Power is power.
 
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JanesJr1

JanesJr1

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Yes, I'm looking at these models because of those reviews. Originally, all I wanted was to be sure of enough power for 16 ohm DCA headphones, and it seemed to me to be simple enough to get balanced connections as an efficient way to get some headroom. Then I got confused by the different versions of "balanced" with Topping and thought I should know more... either because it makes a difference -- or just because I'll learn something about digital audio, which is my weak point.

And Amir always warns of ground loop problems, although I've never been burned by that problem and sort of take it on faith.

Bottom line, I kind of like the A50s to get good power into the headphones, and am less worried about balanced circuits on the input or pre-amp side. But what do I really know? So I'm asking. Thank you for your advice!
 

mugbot

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For further information I have a pair of DCA A2 Noire's and they are easily powered by my RME ADI-2 DAC. Both of these amps provide way more power than that, so you'll be totally fine power wise with either choice.
 

pvehling

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Does the L50 RCA input only output to RCA since it's a passthrough? So it won't be able to have RCA in -> Balanced out?
 

majingotan

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Yes, I'm looking at these models because of those reviews. Originally, all I wanted was to be sure of enough power for 16 ohm DCA headphones, and it seemed to me to be simple enough to get balanced connections as an efficient way to get some headroom. Then I got confused by the different versions of "balanced" with Topping and thought I should know more... either because it makes a difference -- or just because I'll learn something about digital audio, which is my weak point.

And Amir always warns of ground loop problems, although I've never been burned by that problem and sort of take it on faith.

Bottom line, I kind of like the A50s to get good power into the headphones, and am less worried about balanced circuits on the input or pre-amp side. But what do I really know? So I'm asking. Thank you for your advice!

L50 is already overkill for a 16 ohm DCA Aeons. 7 volts and 3.5W is ear bleeding loud except for maybe Susvara (even that is arguable)

PS: I'm going to schiitr in a few hours to demo the Aeon 2's again out of my DAP (3V max without load, and would most likely be less than 1.5 volts when there's a 16 ohm load guesstimate). I'm already predicting that I won't even be reaching 1V RMS (2/3rd of max volume of my DAP) out of the Aeons before the volume feels very unconfortable for a few seconds
 
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JanesJr1

JanesJr1

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L50 is already overkill for a 16 ohm DCA Aeons. 7 volts and 3.5W is ear bleeding loud except for maybe Susvara (even that is arguable)

PS: I'm going to schiitr in a few hours to demo the Aeon 2's again out of my DAP (3V max without load, and would most likely be less than 1.5 volts when there's a 16 ohm load guesstimate). I'm already predicting that I won't even be reaching 1V RMS (2/3rd of max volume of my DAP) out of the Aeons before the volume feels very unconfortable for a few seconds
Hi Majingotan. That post of mine is pretty old, i've had the A50s for 6 months or so, and agree with you that they have more than enough power for the current-hungry DCA phones, especially since I have balanced cables. If I'd done the math, I probably wouldn't have upgraded from my JDS Labs Atom amp, which also drives them fine SE. But now that I've got the A50s, it's also a nice amp.

I can drive the DCA's even with 2 dongles, the Hidizs S9 Pro and the E1DA 9038s G3 (using the balanced output). i've read reviews of the DCA headphones claiming deeper, cleaner bass with really highly-powered amps and I don't believe it. The max SPL changes with more power, and you do need a separate amp or very powerful dongle, but I think the rest is doubtful if you've got a decent, middle-of-the-road amp.

What is "schittr"? Is that a Schitt joke-name for their home office or something?

Oh, and by the way, good luck with the new phones!
 

majingotan

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Schiitr is Schiit’s actual retail store where you can demo every lineup they have BTW. They’ve got a couple of demo headphones but you go there to purchase amps and DACs only

Regards to amping it up, I do not find a difference in their lineup except for the tube amp, Mjolnir 2 where there’s tube distortion injected across all frequencies (probably a case where Aeons bass appear punchier and having more meat to the timbre from bass all the way to treble, a definite byproduct of tubes, and also more harmonic reverberations across the board) All of their amps are able to power the Aeon 2 without issues.

For my DAP, at roughly 2/3rd of max 110/150, I’m already hitting uncomfortably loud volumes by ear and it’s confirmed with my rough phone volume measurement. I confirm with my empirical testing that Aeons sound the same except for super weak dongles and deliberate injection of harmonic distortion from tube amp.

C138E419-CF5B-4A81-B15A-2A83EF681294.png
 
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JanesJr1

JanesJr1

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Schiitr is Schiit’s actual retail store where you can demo every lineup they have BTW. They’ve got a couple of demo headphones but you go there to purchase amps and DACs only

Regards to amping it up, I do not find a difference in their lineup except for the tube amp, Mjolnir 2 where there’s tube distortion injected across all frequencies (probably a case where Aeons bass appear punchier and having more meat to the timbre from bass all the way to treble, a definite byproduct of tubes, and also more harmonic reverberations across the board) All of their amps are able to power the Aeon 2 without issues.

For my DAP, at roughly 2/3rd of max 110/150, I’m already hitting uncomfortably loud volumes by ear and it’s confirmed with my rough phone volume measurement. I confirm with my empirical testing that Aeons sound the same except for super weak dongles and deliberate injection of harmonic distortion from tube amp.

View attachment 217428
Wow! A fast, concise test of my question, and you put an interesting spin on it with the tube amp ...
 
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JanesJr1

JanesJr1

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Schiitr is Schiit’s actual retail store where you can demo every lineup they have BTW. They’ve got a couple of demo headphones but you go there to purchase amps and DACs only

Regards to amping it up, I do not find a difference in their lineup except for the tube amp, Mjolnir 2 where there’s tube distortion injected across all frequencies (probably a case where Aeons bass appear punchier and having more meat to the timbre from bass all the way to treble, a definite byproduct of tubes, and also more harmonic reverberations across the board) All of their amps are able to power the Aeon 2 without issues.

For my DAP, at roughly 2/3rd of max 110/150, I’m already hitting uncomfortably loud volumes by ear and it’s confirmed with my rough phone volume measurement. I confirm with my empirical testing that Aeons sound the same except for super weak dongles and deliberate injection of harmonic distortion from tube amp.

View attachment 217428
Check out another ASR member's take on the headphone / SPL question at https://audiosciencereview.com/foru...er-with-more-juice-current.35600/post-1243441
 

majingotan

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Wow! A fast, concise test of my question, and you put an interesting spin on it with the tube amp ...

Check out another ASR member's take on the headphone / SPL question at https://audiosciencereview.com/foru...er-with-more-juice-current.35600/post-1243441

Agreed! Loudness will be perceived as better of course. I was roughly measuring each amp with pink noise to roughly 75 dB before I sighted A/B them. I'm not keen on subjective flowery descriptions so I'll just come up with analogy for that tube sound: it's similar to turning on "dolby headphone" DSP effect (just the harmonic richness of tone plus surround sound effect that I hear when I used to play DVDs with Dolby headphones through cyberlink powerDVD, Mjolnir 2 sounded similarly close to that hopefully you get the idea. It's IMO not truly an FR eq effect since competent tube amps are linear in frequency response anyways).
 
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JanesJr1

JanesJr1

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Agreed! Loudness will be perceived as better of course. I was roughly measuring each amp with pink noise to roughly 75 dB before I sighted A/B them. I'm not keen on subjective flowery descriptions so I'll just come up with analogy for that tube sound: it's similar to turning on "dolby headphone" DSP effect (just the harmonic richness of tone plus surround sound effect that I hear when I used to play DVDs with Dolby headphones through cyberlink powerDVD, Mjolnir 2 sounded similarly close to that hopefully you get the idea. It's IMO not truly an FR eq effect since competent tube amps are linear in frequency response anyways).
I've always avoided signal distortions like dolby or delay. No necessary reason, just abstract loyalty to "straight wire with gain". Back in the 80's and 90's, I did set up surround sound, but only by wiring the speakers as originally proposed by David Hafler, so as to channel out-of-phase ambience signal from the original recording venue to the surround speakers. It didn't add anything to the clean signal, just fed the out-of-phase portion of it to the rear speakers, with a distinct volume control. It actually worked perfectly well, setting up a muti-channel/surround ambience without modifying the original signal or blurring the front stereo image. You never were conscious of it unless you turned it off, and the ambience collapsed ... nice!

But when you talk about Dolby DSP effects, I've never heard what they sound like. I also avoided tubes as coloration, just on principle. I don't know that I was right; it would be helpful to have had wider experience. I just couldn't bring myself to spend anything on solutions that could modify, color or add to the original recording.
 

majingotan

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I've always avoided signal distortions like dolby or delay. No necessary reason, just abstract loyalty to "straight wire with gain". Back in the 80's and 90's, I did set up surround sound, but only by wiring the speakers as originally proposed by David Hafler, so as to channel out-of-phase ambience signal from the original recording venue to the surround speakers. It didn't add anything to the clean signal, just fed the out-of-phase portion of it to the rear speakers, with a distinct volume control. It actually worked perfectly well, setting up a muti-channel/surround ambience without modifying the original signal or blurring the front stereo image. You never were conscious of it unless you turned it off, and the ambience collapsed ... nice!

But when you talk about Dolby DSP effects, I've never heard what they sound like. I also avoided tubes as coloration, just on principle. I don't know that I was right; it would be helpful to have had wider experience. I just couldn't bring myself to spend anything on solutions that could modify, color or add to the original recording.

Both L50, A50s and dongles are essentially wire with gain as long as SINAD at 50mV or higher is greater than for me 80 dB SINAD due to masking audibility. You can test distortion yourself using this https://www.audiosciencereview.com/...t-audibility-of-distortions.10163/post-277173

IMO, I do think you're currently suffering with "audio nervosa" (in objective area at least) with having a balanced setup. I reiterate those don't matter at all unless your amp is a true balanced in and balanced out and was never converted to SE in any stage (yes the are amps that use op-amp to convert the balanced to SE and it goes back to balanced with an op-amp splitter, e.g. the L50). A50s doesn't qualify since it only has SE in and not balanced. (I suspect it uses op-amp splitter right after SE in to convert it to balanced)

1. The L50 has a SE amplifier, yet has an XLR headphone output circuit. Does that mean that there is no doubling of the power to the headphones, but rather just a mechanism to pre-empt ground loops?

There's doubling of power due to op-amp splitting for balanced out. As for ground loops, I don't think the L50 can reject that or any of the true fully balanced amp since the balanced connections reject outside interference only from cable and not from a ground loop within the system (the ground loop will act as signal rather than noise in this case)

2. The L50 has a pass-through line-in/line-out for non-headphone outputs. But it also accepts balanced inputs. Does that mean that balanced inputs are no longer balanced when passed to an external device (non-headphone)? Or (showing my technical naivete, perhaps) is the pass-through somehow transparent enough to maintain balance from external input to amp output?

The pass through is definitely pass through since it only goes through the circuit as passive (the node for the headphone out amplification circuitry is turned-off) on both balanced and unbalanced ports. You cannot convert the balanced to se and vice versa unless there are op-amp splitters along the signal path on the passthrough node. Ask Topping, but their page says SE to SE and TRS to TRS only so most likely it's a true passthrough signal only rather than having an op-amp to perform the conversions

3. Since the A50s has RCA output connectors for non-headphone devices, there must be no way to use the A50s in balanced mode with active speakers, despite the balanced amplifier circuit ... am I right? (Topping doesn't explicitly say anywhere that balanced mode applies only to headphones with the A50s.)

Nope. RCA is SE as it only has a ground and signal unlike TRS or XLR or 4.4mm

4. With the L50, due to the pass-through, I assume the volume knob doesn't work with the pass-through signal, as it would with the headphone output. I guess that means that to control a powered speaker with, say, a PC's streaming input signal, the volume control for the whole system could only be the PC's volume control or an external DAC, if there is one?

Correct. You would need something like a Schiit Sys or a passive volume knob like the Mackie Big Knob for volume control of monitors if you don't want to control the volume digitally with your PC with the L50

5. I know this has to be a hokey thought, but there's no way to use a 4.4mm balanced output to drive an active speaker in balanced mode, is there?

You can. Just use a 4.4mm (with ground pin to 3.5mm/6.3mm) to 3 pin xlr pairs and you're good to go :). You must have the 3.5mm/6.3mm ground pin as to not create ground loops (since the ground pin for XLR pairs must have the same common node)

6. Topping's literature doesn't explain this all very well, except to hint that the L50's pass-through feature makes it somehow advantaged to use with active speakers ... Although elsewhere, Topping says the A50s (with SE outputs to active speakers but with a pre-amp function) is just dandy to use with active speakers. What's the deciding factor?

You can decide based on my answers on question 1-5 :)
 
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JanesJr1

JanesJr1

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Both L50, A50s and dongles are essentially wire with gain as long as SINAD at 50mV or higher is greater than for me 80 dB SINAD due to masking audibility. You can test distortion yourself using this https://www.audiosciencereview.com/...t-audibility-of-distortions.10163/post-277173

IMO, I do think you're currently suffering with "audio nervosa" (in objective area at least) with having a balanced setup. I reiterate those don't matter at all unless your amp is a true balanced in and balanced out and was never converted to SE in any stage (yes the are amps that use op-amp to convert the balanced to SE and it goes back to balanced with an op-amp splitter, e.g. the L50). A50s doesn't qualify since it only has SE in and not balanced. (I suspect it uses op-amp splitter right after SE in to convert it to balanced)



There's doubling of power due to op-amp splitting for balanced out. As for ground loops, I don't think the L50 can reject that or any of the true fully balanced amp since the balanced connections reject outside interference only from cable and not from a ground loop within the system (the ground loop will act as signal rather than noise in this case)



The pass through is definitely pass through since it only goes through the circuit as passive (the node for the headphone out amplification circuitry is turned-off) on both balanced and unbalanced ports. You cannot convert the balanced to se and vice versa unless there are op-amp splitters along the signal path on the passthrough node. Ask Topping, but their page says SE to SE and TRS to TRS only so most likely it's a true passthrough signal only rather than having an op-amp to perform the conversions



Nope. RCA is SE as it only has a ground and signal unlike TRS or XLR or 4.4mm



Correct. You would need something like a Schiit Sys or a passive volume knob like the Mackie Big Knob for volume control of monitors if you don't want to control the volume digitally with your PC with the L50



You can. Just use a 4.4mm (with ground pin to 3.5mm/6.3mm) to 3 pin xlr pairs and you're good to go :). You must have the 3.5mm/6.3mm ground pin as to not create ground loops (since the ground pin for XLR pairs must have the same common node)



You can decide based on my answers on question 1-5 :)
As i said, I've had the A50s for 6 months since I posted those questions. I got it because I liked the compact form factor and could get extra power out of the balanced output. I didn't do it for ground loops or anything. BTW although the inputs are SE, the amp itself is internally balanced, perhaps with some benefit to crosstalk, and the 4.4 mm Pentaconn headphone jack does channel a lot of power for such a small chassis.

As I said earlier, with hindsight, I didn't really need that much power for the Dan Clark headphones.

The pre-amp function does allow me to drive active desktop monitors with volume control, which I preferred over the L50 pass-through when I got the amp, although I did have to use hybrid SE RCA-to-XLR cables as you suggest. Seems to work ok.

I like the amp well enough, but may have to test the weak Topping service coverage of the USA. I'm starting to get right-channel drop outs, oddly when inserting both the 1/4-inch and 4.4 mm headphone jacks and sometimes when adjusting volume. If it turns out to be too big of a pain to fix, I'll switch to some domestic manufacturer, like JDS or Schitt.

Thank you for your thoughtful replies on everything!! The only thing I disagree with in a friendly way is that EQ can be easily applied to a vast number of hardware options, whereas the right combination of power, features, price, and distortion (sometimes) may be scarce. The ability to EQ gives me a much wider field of choice than trying to limit myself to tonally perfect hardware that just may not exist.

(I know, EQ doesn't always work. For example, I don't like the bass EQ on my HD6XX phones. It's best for low-distortion transducers, wide-directivity speakers, and may not fix gross tonality problems. But it sure helps in a lot of cases, and is free.)
 
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