Topping L30 II Review (Headphone Amp)

[nanook]

According to the support response and the manual, it seems to be an impedance balanced output.
In that case, no abnormalities will occur even if the cold output is open or shorted to ground. The output circuit will also not be damaged.

The term "impedance balanced" means that the cold leg (XLR pin3) is internally connected to Gnd (XLR pin1) with a resistor that resembles the output resistance of the hot leg (XLR pin2). There's no output stage connected to the cold leg - just a resistor.
-> Using a TS-RCA adapter electrically works just like a real RCA - RCA connection.

There's nothing wrong with this topology, the only disadvantage compared to a true differential output is the maximum output level being 1/2 of the differential output stage (and such high levels are rarely needed).

Note:
Using a TS-RCA adapter on "normal" differential TRS outputs indeed shorts the output driver of the cold leg to gnd. The OpAmp will survive, but it will run hot and if it's a dual OpAmp driving both legs of the output (which usually is the case due to $$$), the signal at the hot leg may show increased distortion.

 

[tonediary]

Thinking of this as my first amp.

Is L30 II a good match with Gustard X20 pro DAC?

Also can the L30 II drive the Hifiman Edition XS comfortably at higher volumes when using EQ (Peace) at -6db?

 

[staticV3]

Is L30 II a good match with Gustard X20 pro DAC?

As good as any

Also can the L30 II drive the Hifiman Edition XS comfortably at higher volumes when using EQ (Peace) at -6db?

With ease.

 

[tonediary]

As good as any


With ease.

Noted. Thank you!

Was thinking of ordering the A70 pro prior to this. After some research i’m convinced i will not hear any audible difference between the two.

 

[ImDino]

As good as any


With ease.

I just noticed mine pans to the left more and more when I'm turning down the knob to the lowest volumes. Is it normal for an amp?

Also, my volume knob isn't smooth all the way, it's like a mix between smooth and scratchy.

 

[unpluggged]

Is it normal for an amp?

It's normal for pontetiometer-based volume controls, especially for cheap ones.

You can try using lower gain setting to somewhat mitigate this.

 

[solderdude]

I just noticed mine pans to the left more and more when I'm turning down the knob to the lowest volumes. Is it normal for an amp?

Also, my volume knob isn't smooth all the way, it's like a mix between smooth and scratchy.

yep.... set the gain to a lower level.
When you have very sensitive ear/headphones and this is problematic even on the lowest gain setting you can use a passive attenuator or buy an amplifier with digital (relay or otherwise) volume control.
Some copies are a bit worse than others. It is caused by mechanical tolerances in the construction of the small sized 'dual gang' volume controls and unavoidable.

 

[ImDino]

yep.... set the gain to a lower level.
When you have very sensitive ear/headphones and this is problematic even on the lowest gain setting you can use a passive attenuator or buy an amplifier with digital (relay or otherwise) volume control.
Some copies are a bit worse than others. It is caused by mechanical tolerances in the construction of the small sized 'dual gang' volume controls and unavoidable.

Thank you, I was just worried I had a defect unit.

 

[Roland68]

Noted. Thank you!

Was thinking of ordering the A70 pro prior to this. After some research i’m convinced i will not hear any audible difference between the two.

You should also check out the Sabaj A20h.
Symmetrical HPA, including relay-based volume control with absolute channel equality (like A70 Pro), remote control, display, symmetrical input and true symmetrical output with a maximum of 4.7 watts at 32 ohms. Plus a good and powerful switching power supply and not just a cheap transformer.
For around 120 €/$ or less, it is an absolute bargain in my opinion and has the best price-performance ratio on the market.

 

[tonediary]

You should also check out the Sabaj A20h.
Symmetrical HPA, including relay-based volume control with absolute channel equality (like A70 Pro), remote control, display, symmetrical input and true symmetrical output with a maximum of 4.7 watts at 32 ohms. Plus a good and powerful switching power supply and not just a cheap transformer.
For around 120 €/$ or less, it is an absolute bargain in my opinion and has the best price-performance ratio on the market.

Thank you for the advice.. Looks like a great amp. I've already ordered the L30 II though.

 

[mike7877]

After having my E30 II for a year and using it heavily since purchase until I switched to my A70 Pro about half a year ago and returning to the E30 II, I am of the firm belief: "anyone who wants a clean, powerful, headphone amp, with an accurate, non-fatiguing, full spectrum sound, should buy an L30 II"

When I bought my L30 II, I also bought an E30 II. Though it looks like the L30 II and connects to the L30 II, and even it was designed to be the matching partner to the L30 II, the E30 II does not belong with the L30 II. Get something better. For example, Topping's E70 Velvet would be a good match.

The L30 II's only weakness is its potentiometer. It's not a bad pot, and Amir's measurements in this review show good channel matching across the entire range except for a small bit near the very beginning (bottom - you don't use the knob there). I'm only bringing this up because it is its weakest link. Before I got my A70 Pro with switched resistor volume control, I didn't notice the L30 II's potentiometer - only after experiencing the A70 Pro for a few weeks and going back to the L30 II could I identify the difference. Even now, with much more experience, most of the time I don't perceive an effect from the pot. Unfortunately a switched resistor network just isn't in the L30 II's parts budget. Even if it was, the L would have to be so much bigger, and its small size is part of its charm!

Amplification quality and power is simply amazing. E30 II! E30 II! E30 II! Get.. yourself.. an E-30-II !!!
If you game with a decent headset and use your motherboard's decent sound card or something from Creative with a good DAC to drive them, but they're only capable of putting out 50-150mW power (the cards..), an E30 II would make your days.

Although L was only tested down to 12 ohms here, I've attached it to speakers with the lowest impedance down in the 4s (using my hand-crafted (lol), homemade, quality 1/4" male stereo plug, to 16ga wires, to wall-receptacle piece designed to accept banana plugs, When attached to my pair of 90dB/W Monitor Audio Silver 6 (they're fronts in my home theater: dual 6" + tweeters in 2.5 way design, crossed 700Hz and 2.7kHz), they fill a room with sound 14'x19'x8' (L x W x H) at such a level that conversation is beginning to get annoying (like this sentence...).With no distortion, either! For example, songs off Rush's 1982 album "Signals", the woofers will move 3-3.5mm with the kick before clipping comes in. I had my scope attached and this is verified without clipping!

Clipping... Uh-oh - I think that's its second weakness. Not really though, because it doesn't affect anything negatively because it's never gonna happen with actual headphones on your head because they'll be fried or you'll be deaf. When it happens, though, it happens weird. Most amps don't, when they clip, ring with a bunch of HF energy in the many-megahertz range. I forget if it rings at around like 4 or 20MHz, but when it clips, (like it did at, around 4 watts into these speakers), its amplitude [the ringing's], as a percentage of the waveform, is between ~20-25%. It quickly recovers and doesn't go into oscillation or anything. It'll complete a few to ten cycles.

Since headphones are already taking 100% of the power into a single driver and the power doesn't increase more than like 10-15% during clipping, I'm going to say that they won't suffer any ill effects. If, for some weird reason, like me, you're driving a pair of speakers with your L, its total power output power isn't enough to cook a tweeter, let alone just a quarter of it. Besides, most tweeters' impedances will already be >100 ohms up there. So it's not unsafe. Just weird. Some amps, the second they clip you can hear it. Not the L30 II (like you might have assumed because of how weird it is).

That's all! Internally, its capacitors are high quality 35V, 3300uf, very low ESR. I believe there are two op-amps - one which receives input from the RCA plugs, and another which is connected with the TPA6120A2 in a (proprietary?) style feedback circuit. The OPA1612 is the gem attached to the 6120A2, and the one feeding the 1612, is either another 1612, or a NE5532. There aren't pictures of the [potentially] non 1612, and the L30 II's predecessor (predictably named L30 - how boring, they should've picked something else. L30? Really, Topping?) contains an NE5532 for the RCA jack. Ironically, unfortunately, coincidentally, whatever-ly, the boring L30's pictures online are only available with the 6120A2 attached op-amp blown up! Yes, I don't know what's paired to the 6120A2 in the L30, but the 5532 is there, plain to see. Topping does seem to have settled on using 1612s almost everywhere. Sometimes they'll use the 1656 though... In my A70 Pro the 1612s are all paired with a 1656. The 1656 is a JFET, known to be good for inputs, so it's entirely possible the L30 II's input is a 1656, and the amplifier part is 1612. This isn't critical information, just potentially interesting. Maybe someone who reads this has seen both of the opa's in one or both of these devices and can fill us in in a post shortly under here! We can hope...

Oh, before I got sidetracked - those 35V capacitors are charged by the HVAC (high voltage AC, not ventilation) to 15VAC adaptor. I don't know exactly why they chose this voltage, it does seem a bit high for the 6120A2 ("A2") maximum 33V (+/- 16.5V, preferred 30V/ +/-15V input voltage. Let's say they went with 16V... Each rail is regulated by a transistor under the heatsink closest to the caps - they must be dissipating power equal to the 6120A2s current draw multiplied by the voltage difference between the caps and their output: 15VAC = 21.2VDC rectified and split, meaning 5V x the current... The adaptor is only rated for 1000mA, so I guess as power goes up (causing current to go up) voltage goes down - the higher the draw, the more the drop. Basically the voltage goes down which compensates for the current rising, leaving dissipation not quite as ridiculous as it seemed at first.

So each of the stereo A2s is used mono - not by ignoring one channel (pointless), but in parallel. This is possible because it's a current amplifier. This is what allows the A2's datasheets to declare a 700mA maximum current, and L30 II's specification to be for 1.4A max current! In low and medium gain, max voltage output is 31v peak to peak. High gain? now you get 37V! I don't know how this is possible... Maybe it's a mistake. 31V makes sense, 37V does not... Not with 6120A2's being run at maximum +/- 16.5V. Unless Topping has some specific knowledge on A2's process being compatible with higher voltages than TI claims in the datasheet. I know of some op amps which are said to be OK to 21, maybe 22V, and their datasheet says 17V recommended, 18 max. That's 4-5V... Going from 33 to 37 is just 4-5V as well...

Low impedance average efficiency headphones will be able to be driven adequately in low gain mode for all but pretty extreme listening scenarios (caveat: your source must be line level). Low starts not quite being enough for higher impedance average sensitivity headphones pretty quickly though, like, for example, Sennheiser's HD 650. At normal listening levels, some songs recorded much more quietly than usual will need medium gain. Next is good to know for those with low impedance, high sensitivity IEMs (think 10 ohms and efficient efficient efficient!) -in its lowest gain setting, our beloved L is especially quiet: quieter than all other headphone amps measured and reviewed here! And not by a small amount! It's an entire 5dB quieter than the next ~15 devices - at 50mV, dynamic range is an entire.... 100dB! That's right... A hundred! Next closest is [obviously] 95dB. There are a bunch of really good headphone amps in that list of ~15, before it drops to 94 and another dozen or so devices...
Personally, I use the medium gain setting with my 300 ohm HD650 cans, and it covers everything. I never hear any hiss either. This isn't surprising, as L's dynamic range is an astounding hundred forty four decibels! Being single-ended helps this. One caveat is this - if the DAC you're using is balanced and single ended, it's likely an op amp is used to combine the balanceds <- underlined in red but it's a word in this case! This causes a loss in dynamic range, typically in the 4-6dB range. So while the dynamic range is higher, it comes at a bit of a cost. But when your DAC's dynamic range is over 125dB in single ended mode anyway, it doesn't matter all that much!


OK, this is getting too long - I don't want to make it unreadable! I'll finish here. Get an L30 II!

 

[wineaholic]

Does the RCA output on this unit degrade the signal? Is it best to use a passive input switcher to connect the headphone amp and speaker amp, instead of connecting them in line?

 

[Rja4000]

Does the RCA output on this unit degrade the signal?

Strange question.
Any additional element in the chain "degrades" the signal, somehow.
The question is "how much".

Here, the "degradation" is so low one may hardly measure it with very sensitive instruments.
It's of absolutely no consequence on audio.

And it's most probably much less degradation than your poweramp would bring for the additional gain - if some is needed.

Now, if you don't need additional gain, then you may be good without it.

And it's also important to understand that the gain range selection and volume control are active both for the RCA output and for the headphones output.
So if you want to keep them independent, of course, you'll cable both amps in parallel rather than pluging the power amp at the RCA output.

 

[Roland68]

That's all! Internally, its capacitors are high quality 35V, 3300uf, very low ESR. I believe there are two op-amps - one which receives input from the RCA plugs, and another which is connected with the TPA6120A2 in a (proprietary?) style feedback circuit. The OPA1612 is the gem attached to the 6120A2, and the one feeding the 1612, is either another 1612, or a NE5532. There aren't pictures of the [potentially] non 1612, and the L30 II's predecessor (predictably named L30 - how boring, they should've picked something else. L30? Really, Topping?) contains an NE5532 for the RCA jack. Ironically, unfortunately, coincidentally, whatever-ly, the boring L30's pictures online are only available with the 6120A2 attached op-amp blown up! Yes, I don't know what's paired to the 6120A2 in the L30, but the 5532 is there, plain to see. Topping does seem to have settled on using 1612s almost everywhere. Sometimes they'll use the 1656 though... In my A70 Pro the 1612s are all paired with a 1656. The 1656 is a JFET, known to be good for inputs, so it's entirely possible the L30 II's input is a 1656, and the amplifier part is 1612. This isn't critical information, just potentially interesting. Maybe someone who reads this has seen both of the opa's in one or both of these devices and can fill us in in a post shortly under here! We can hope...

Oh, before I got sidetracked - those 35V capacitors are charged by the HVAC (high voltage AC, not ventilation) to 15VAC adaptor. I don't know exactly why they chose this voltage, it does seem a bit high for the 6120A2 ("A2") maximum 33V (+/- 16.5V, preferred 30V/ +/-15V input voltage. Let's say they went with 16V... Each rail is regulated by a transistor under the heatsink closest to the caps - they must be dissipating power equal to the 6120A2s current draw multiplied by the voltage difference between the caps and their output: 15VAC = 21.2VDC rectified and split, meaning 5V x the current... The adaptor is only rated for 1000mA, so I guess as power goes up (causing current to go up) voltage goes down - the higher the draw, the more the drop. Basically the voltage goes down which compensates for the current rising, leaving dissipation not quite as ridiculous as it seemed at first.

So each of the stereo A2s is used mono - not by ignoring one channel (pointless), but in parallel. This is possible because it's a current amplifier. This is what allows the A2's datasheets to declare a 700mA maximum current, and L30 II's specification to be for 1.4A max current! In low and medium gain, max voltage output is 31v peak to peak. High gain? now you get 37V! I don't know how this is possible... Maybe it's a mistake. 31V makes sense, 37V does not... Not with 6120A2's being run at maximum +/- 16.5V. Unless Topping has some specific knowledge on A2's process being compatible with higher voltages than TI claims in the datasheet. I know of some op amps which are said to be OK to 21, maybe 22V, and their datasheet says 17V recommended, 18 max. That's 4-5V... Going from 33 to 37 is just 4-5V as well...

Your assumptions about power, voltages and OPAmps are incorrect, misleading and have been discussed several times in the forum.
The transformer has a voltage of 15 volts and delivers 1 A, which corresponds to 15 watts. Even with an incredibly poor efficiency of 50% (which it does not have), it is still oversized and cannot be a limitation.

A half-wave rectification is used for the necessary dual voltage (+/-). This gives you an approx. +23V/-23V DC voltage from 2 half-waves at 15 volts AC. for supply. Other manufacturers do the same with headphone amplifiers.
The voltage is then stabilized at +15V/-15V using a linear voltage regulator, as with the L30. Addendum: My mistake, it is actually only +12.5V/-12.5V on R/LVCC+ and R/LVCC- on the L30 II, it has been over 2 years since I measured that. On the L30 the voltage was actually +15V/-15V.
These voltages were measured by me and other users and confirmed.
So there are no secrets or higher/too high voltages, you can measure them yourself.

The NE5532 and LT072 used in the L30 and L30 II are only used for DC detection, are not in the audio path (i.e. not in the amplifier circuit, in the input or output) and have no effect on the sound.

 

[mike7877]

The voltage is then stabilized at +15V/-15V using a linear voltage regulator, as with the L30.

When Suzy answers 8 after being asked "what's 5x3?" you don't tell her she's "incorrect and misleading". That'd be something more likely to be said by someone who thinks Suzy knows the answer and some of the other kids (who are trying to learn) don't, and she wants to screw them up! "Mislead" has the strongest connotation to deliberate deception of all its synonyms.

Onto business:

L30 II - TOPPING AUDIO

www.toppingaudio.com

Click specs, page down 3x, and the chart you see will include this bit I snipped out of it.

https://www.ti.com/lit/ds/symlink/tpa6120a2.pdf

On the top of Page 5, 7.5: Electrical Characteristics

Highlighted above is the maximum voltage output capability of the TPA6120A2 connected to (+15V / -15V). We can either add those together or halve Topping's 37 Since

37 / 2 = 18.5
15 + 15 = 30

Can a linear amplifier running on 30 volts cause its output to be 37 volts?
Not last time I checked.

Does any manufacturer claim on their amplifier datasheets that the output voltage swing of their amplifiers exceeds supply by 23 percent?
No, the standard amount amplifiers can swing past their rails is 12%..................


You say that 15 turns into +23V / -23V
That's misleading, sir: 15 multiplied by the root of 2 is 21, so


How much should we expect to droop to on those 35V bulk caps when the E30 II (or E30..) is doing easy work as usual, something like 30mW (98% of everyone everywhere's dissipation with dynamic drivers)

I think remember measuring power draw of the E30 II with my meter while idle, and it was like 3-4W
E30 II 15VAC 1A adaptor AC voltage at rest: 19.3V with 120.1V in

19.3-15 = 4.3V

15V * 1A = 15VA

3.5VA/15VA = 0.2333333

4.3V * 0.2333333 = 1.00V

4.3V - 1.0V = 3.3V

15+3.3 = 18.3V

18.3VAC = 25.9V peak

Bringing 25.9V down to 15V is a ha-uuuuge drop

10.9/25.9 = 42%

15/25.9 = 58%

###solution for above: When E30 II is running normally (ie. listening to a tv show through earbuds in a quiet room):
42% of its power dissipation is due to the regulators...

###solution for below: When E30 II is running normal efficiency headphones at 105-110dB level (headphones are 92dB/mW) it uses 1W more power than on and idle:
41% of its power dissipation is due to the regulators...

Instead of the voltage on the caps being 18.3V, the extra watt brings it down to 18.0V (18.01V to be exact...)
25.9V peak turned into 25.5V peak


Standard, nothing special regulators are usually designed keep the AC at least 2V about their output.

If we run on 15V DC, that means we need a minimum of +/- 17V to the regulators


27.2 open turns to 21.2 with 1 full A drawn

How many amps drawn required to drop further to 17?

21.2 - 17 = 4.2

4.2/6 * 1A = 0.7A

Total max draw design is 1.7A, but adaptor is 1.0A!
This is ... at least uncommon. It could be due to the transient nature of music that the transformer can be undersized like this, but looking at everything together, it makes more sense the adaptor is correctly sized and the internal voltage the 18.3VAC (25.8V peak) {(idle)} and 15.0VAC (21.2V peak) {(full load)}

Put another way, it doesn't make sense to leave an entire 6.2 volts above the regulated rail... we need 2, not 6.2.
The way it works out, the regulators, being fed from a 15VAC transformer, burn an extra watt when the 6120 amps draw somewhere between 60-150mA more than they do when idle (this would be during semi-loud music), than the would if a 12VAC transformer was used instead. Keep in mind, this is only if 15V is what the 6120A2s are getting....
If that 12VAC transformer powering the E30 II with its + / - 15V rails was also rated for 1A, there would be no change in amp performance



The 6120A2 must be higher inside...


I don't see how the 6120A2's Vcc regulation can be done to anything under + / - 21.15 volts!

Why? Because 37V peak to peak is 18.5V (one way). The 6120 datasheet shows that you need to give it 2.5 to 2.8V more than you from the output, so:

18.5 + [(2.5+2.8) / 2] (unnecessary squares - just to make it clear

18.5 + 2.65 = 21.2V

Wait a second.... 15 * sqrt2 = 21.2


What a coincidence...

 

[IgorD]

It probably has been discussed, feel free to point me in. Why Topping L 30 II was removed from recent charts of top headphone amplifiers?

 

[staticV3]

It probably has been discussed, feel free to point me in. Why Topping L 30 II was removed from recent charts of top headphone amplifiers?

Amir does not consistently maintain a headphone Amp ranking the same way he does for DACs for example.

The L30II's 50mV result Amir got I suspect was erroneous and removed from the ranking as a result (merely speculation).

 

[IgorD]

Thank you for explanation.
If it was wrong measurement then ok, we are all humans and propense to errors.

 

[louwii]

Not sure if the Topping L30 II really needs more praise. But here I am. I'm pairing mine with a Topping E50 to drive some Sennheiser HD560S. This is my first experience with a proper headphone stack and I'm very pleased with it. I was using the HD560S with a simple Apple USB-C to 3.5mm before. Using the DAC + amp transformed the listening experience, I wasn't expecting that much of a difference. Everything is just better. I can't find anything bad to say. The limitation is now the HD560S, a bit weak in the bass department, and I'd also like something with a better soundstage if possible. I'm using PEQ to try to get the best of them, but that can't solve everything.

I might try that stack with some older headphones I have (nothing of quality though compared to the HD560S), to see if it makes them sound better as well, I'm a bit curious.

 

[Rja4000]

The L30II's 50mV result Amir got I suspect was erroneous and removed from the ranking as a result (merely speculation).

I measured 101dB unweighted

If I'm not mistaken, Amir is using CCIR-2K weighting, which should give 1-2dB lower value, so his 100dB 50mV SNR is coherent with my measurement.