Topping L70 Headphone Amp Review

[ErkyPerky]

Precisely.

-Ed

Excellent. Thanks.

 

[grogzilla]

Hi, everybody. I unfortunately don't know much about electronics, but I'm trying to understand things. From what I've gleaned, it seems like it's usually desired for the input impedance on a device to be at least 10-20 times the output impedance of the other device connected to the inputs. What happens if it's a 1:1 ratio between balanced connections instead of 10:1 or higher? Would this cause significant issues of some kind?

I currently have an audio interface (Roland Quad-Capture) that has a specified output impedance of 2k ohms on the balanced outs (TRS), which might be okay when connecting directly to some active monitors that have an input impedance of up to 20k ohms, but maybe not when trying to connect to something like the balanced inputs of this L70 and some other Topping amps? It's been mentioned previously that the input impedance on the L70 is around the same 2k ohms as the output impedance of this interface, so I'm just wondering if hooking the interface up to the amp through their balanced connections would cause problems. The headphone out on the interface has a relatively high output impedance of 47 ohms, so most of my headphones don't "match" well with it, either, but I could potentially run a 1/4" to dual RCA adapter from the headphone out of the interface into the RCA line-ins of the L70 if that would work better. Or is there some other way of doing this that would be more ideal, besides replacing the interface with something that has a lower output impedance?

 

[Burns]

In most reviews and photos E70 & L70 are connected together via XLR connector.

Can someone explain to me why we get "cleaner sound" according to the specification on the SE connection? I'm talking about the DAC to Amplifier connection! See the official product table, I marked it in red

 

[staticV3]

Can someone explain to me why we get "cleaner sound" according to the specification on the SE connection? I'm talking about the DAC to Amplifier connection! See the official product table, I marked it in red

The preamp is likely single-ended internally, so balanced input needs to be converted to SE first, adding some noise.

In any case, the differences are entirely inconsequential and not worth losing sleep over.

 

[Burns]

The preamp is likely single-ended internally, so balanced input needs to be converted to SE first, adding some noise.

In any case, the differences are entirely inconsequential and not worth losing sleep over.

Thank you.

I guess these are textbook differences, inaudible.

I noticed this because I have e70 connected via XLR to a large amplifier powering floorstanding speakers.

Isn't this a bit of a scam on the part of the manufacturer?

I was close to buying another e70 DAC, to have it connected to l70 via XLR, I would have been cheated a bit and lost double the money.

I can easily take the signal from the first DAC from the free SE connectors and pass it to L70
Instead of having:
E70 for floorstanding speakers + E70 for headphones + L70 Amp for headphones. (~300$+300$+300$=over 900$)
I can do this with only two devices:
E70 for floorstanding speakers (XLR) and for headphones (SE) + L70 Amp for headphones. (~300$+300$=over 600$)

 

[staticV3]

Isn't this a bit of a scam on the part of the manufacturer?

Not at all.

Instead of having:
E70 for floorstanding speakers + E70 for headphones + L70 Amp for headphones. (~300$+300$+300$=over 900$)
I can do this with only two devices:
E70 for floorstanding speakers (XLR) and for headphones (SE) + L70 Amp for headphones. (~300$+300$=over 600$)

Correct.

 

[Burns]

The preamp is likely single-ended internally, so balanced input needs to be converted to SE first, adding some noise.

Not at all.

 

[Roland68]

View attachment 413030

You're getting something mixed up. Symmetrical signal transmission only makes sense for cable routes, not in devices.
Topping refers to the symmetrical HPA output stage.

You are of the opinion that the entire signal processing should be symmetrical, and that is precisely what is not desirable and also pointless.
Even in very expensive devices, e.g. 25k range, the input signals are de-balanced and the output signals balanced again.

 

[Burns]

You're getting something mixed up. Symmetrical signal transmission only makes sense for cable routes, not in devices.
Topping refers to the symmetrical HPA output stage.

You are of the opinion that the entire signal processing should be symmetrical, and that is precisely what is not desirable and also pointless.
Even in very expensive devices, e.g. 25k range, the input signals are de-balanced and the output signals balanced again.

I don't know if I'm mistaken, I'll say more, I don't understand it.

Why then take a balanced signal to debalance it?

Can you check for me how the Musical Fidelity M6si amplifier that I have behaves? Please.

 

[staticV3]

Why then take a balanced signal to debalance it?

For its CMRR, the ability to reject EMI

 

[Roland68]

I don't know if I'm mistaken, I'll say more, I don't understand it.

Why then take a balanced signal to debalance it?

Can you check for me how the Musical Fidelity M6si amplifier that I have behaves? Please.

Your Musical Fidelity M6si amplifier is exactly the same, which is easy to recognize by the built-in PGA2320 for volume control, a 2-channel chip. The XLR input signal is also directly de-balanced in the M6si.

I'll break it down very simply.
You would have to invest a lot more effort in development, measurements, components, especially highly selected components, in order not to achieve a worse result. The device alone would probably be 5-6 times as expensive just to keep it from getting worse. But due to the lower number of units and thus lower sales volume, it would be more like 20-30 times as expensive.
An improvement would also be much more difficult and much more expensive.

If you really want to understand why this is the case, you would first have to familiarize yourself with the topic of balanced cabling and understand why it is used, what the advantages and disadvantages are and how it works.
And then you take a closer look at what problems can arise in signal processing when unnecessarily symmetrical signal processing is used, or why.

 

[Burns]

I looked at the XLR cabling,

And then you take a closer look at what problems can arise in signal processing when unnecessarily symmetrical signal processing is used, or why.

Can you link any articles?

But surely there are some fully balanced amplifiers that do not convert the signal, those very expensive McIntosh, Accuphase, D'agostino?

 

[Ahmonge]

Schiit Audio: Audio Products Made in USA

www.schiit.com

Isn't it a balanced HP amplifier and preamp?

 

[Roland68]

I looked at the XLR cabling,

Can you link any articles?

But surely there are some fully balanced amplifiers that do not convert the signal, those very expensive McIntosh, Accuphase, D'agostino?

Please don't be mad at me, but that's no use, I don't have the time to start from scratch.
At ASR and Google you can find hundreds of posts/pages on the subject and it's not an easy field. Many manufacturers have already failed on this topic. The Elliott/esp page should also be helpful for you. But you will find little to nothing about why this is such a bad idea with so many disadvantages, you have to work that out for yourself.

McIntosh definitely not, you should see that at first glance when you look at the back of the MA8950 AC.
Accuphase always had stereo volume potentiometers, so not either. I can't say for the new volume control, probably not, but a look at the circuit diagrams/service manuals should clarify things for you.
The small signal range of the D'agostino integrated amplifier could actually be completely symmetrical internally. I heard the amplifier at a demonstration this year without knowing what kind of amplifier it was. I only saw that later in the pictures I took for documentation. It wasn't spectacular for me, nor did it make an impression. The measurements given aren't bad, but at that price? Oh well.

But it doesn't change the fact that you're chasing a white rabbit and wasting your time (and maybe money) on something that's absolutely pointless. You have a thought in your head that only you can free yourself from, because you're already resistant to any advice and experience.

Two more comments on that.
1. In the pro audio sector, too, there are only symmetrical cable transmissions and no symmetrical signal processing. Here, too, the signals are symmetrical at the output and de-symmetrical at the input.
You do realize that all the music you hear was produced this way. And the signals were really converted in this way countless times. And you think that one thing would change anything?

2. I actually once thought that symmetrical signal processing was the holy grail. Then we started a project on the topic, in which several measurement technology engineers, manufacturers and application developers were involved. Everyone involved assumed that this would take us a significant step forward in development.
The result was simple and meaningful, absolute nonsense. Lots of sources of problems and stumbling blocks and nothing to gain.

But never hold up travelers.

 

[Roland68]

Schiit Audio: Audio Products Made in USA

www.schiit.com

Isn't it a balanced HP amplifier and preamp?

I don't know the circuit of the device, but judging by the potentiometer, the signal path should be completely symmetrical.
With such a simple device, signal input -> potentiometer -> HPA, without further signal processing, the effects are not so bad, but both the L70 and the approx. $100 amplifiers from Schiit have better measured values. The potentiometer deviations also have a much greater effect per channel, also a disadvantage of my SA-1.

But Schitt is definitely reaching the target group that absolutely wants a "real" internally symmetrical HPA or preamp. Not stupid.
Perhaps also a possible solution for @Burns.

 

[nagster]

But surely there are some fully balanced amplifiers that do not convert the signal,

Is it a balanced transmission without differential amplification?
What are the advantages of an amplifier with two single-ended input amplifiers lined up next to each other?

 

[Burns]

Is it a balanced transmission without differential amplification?
What are the advantages of an amplifier with two single-ended input amplifiers lined up next to each other?

You're asking me?

I don't know, I don't know anything about it
So I'm asking if this shouldn't be the idea of buying and connecting the L70 / A70Pro / A90 / Pre90 with two B200 power amplifiers?

B200 - TOPPING AUDIO

www.toppingaudio.com

I don't understand the structure of connecting, for example, DAC E70 >>> preamp L70 >>> 2x B200
Where will the losses and conversion be the smallest, even if it is theoretical and textbook?
It turns out that from DAC E70 to L70 I should exit and enter with RCA cables (SE to SE) and from L70 to B200 I should exit and connect it XLR to XLR (there is no other possibility)

And shouldn't it be called and actually be fully balanced, whatever that means in this version in the internal structure and not just the way it's connected? Please don't focus only on the headphones, but consider the rear outputs that the L70 / A70Pro / A90 / Pre90 devices received.

The second issue is that the E70 DAC (SE 2.5V / XLR 5V) connects it only in DAC mode with parallel RCA / XLR cables (both SE and XLR outputs active, the same music comes out) with the Topping L50 or MF M6si amplifier.
Why does changing the input source in the Topping L50 or MF M6si cause the playback of the XLR source to be louder than the SE? The SE/XLR change in the L50 or MF M6si is immediate. You can hear it with your ears and with a dB meter
Shouldn't the volume level be the same since you confirmed earlier that there is an internal conversion to SE anyway?

 

[EddNog]

You're asking me?

I don't know, I don't know anything about it
So I'm asking if this shouldn't be the idea of buying and connecting the L70 / A70Pro / A90 / Pre90 with two B200 power amplifiers?

B200 - TOPPING AUDIO

www.toppingaudio.com

And shouldn't it be called and actually be fully balanced, whatever that means in this version in the internal structure and not just the way it's connected? Please don't focus only on the headphones, but consider the rear outputs that the L70 / A70Pro / A90 / Pre90 devices received.

The second issue is that the E70 DAC (SE 2.5V / XLR 5V) connects it only in DAC mode with parallel RCA / XLR cables (both SE and XLR outputs active, the same music comes out) with the Topping L50 or MF M6si amplifier.
Why does changing the input source in the Topping L50 or MF M6si cause the playback of the XLR source to be louder than the SE? The SE/XLR change in the L50 or MF M6si is immediate. You can hear it with your ears and with a dB meter
Shouldn't the volume level be the same since you confirmed earlier that there is an internal conversion to SE anyway?

If the output is true balanced differential, because it is combined voltage of positive and negative signals, it is naturally +6dB louder on balanced versus single-ended.

-Ed

 

[bequietjk]

After a few long LONG years of using only my motu m2 hp output i've finally received the L70 and it feels like im right back home again. The last amp I had was a bottlehead crack and a pair of HD600's. Now sitting with me is the L70 feeding my DT 700 pro x and im hearing truly what these were ment to sound like. AMAZING!

For the owners out there have you had to do any firmware updates or is it pretty much plug and play?

 

[jaibautista]

I wasn't really in the market for a balanced desktop headphone amp until I started fiddling with my old yet trusty Cypher Labs Duet portable amp. Shortly thereafter, I began to wonder if I'm missing anything with my listening experience by not having a proper balanced headphone amp. Good thing our local headphone shop still had an unopened unit of the L70 and allowed me to try it; it didn't take long for me to make the decision to get one.

Crazy performance for the price, with loads of power on tap in a physical package that doesn't have to take up the entire desk (and doesn't heat up like a pizza oven). Can't wait to receive my Aliexpress balanced cable for my Fostex T50RP 50th Anniversary pair and unlock its full sound with the L70 (it's just too hard to drive them single-ended); I thought the Audeze LCD-2 and Hifiman Arya Organic sounded great with the L70 via balanced headphone out.

We really are living in a golden age of headphone amplification!