Thoughts or analysis on Topping A30 Amp or Amp portion of DX7s?

[VanNeumann]

I know a few members have had the Topping A30 and Dx7/Dx7s. Any thoughts on the sound and build quality of the amps or amp portion of the Dx7/Dx7s?

 

[mindbomb]

I have thoughts on it. Topping puts a heatsink on their tpa6120a2 chip, and I suspect that's why it will perform well relative to a lot of other amps that use the same chip. I'm not sure how the high output impedance will affect real life dynamic headphones though.

 

[VanNeumann]

Are the output impedances for the A30 and Dx7s 10Ohms? Also, do you experience any distortion on low volume or relatively high volumes?

 

[mindbomb]

Oh , I don't have one. There are pictures of the a30's pcb on the topping website. Yea, it has 10 ohm output impedance on the normal headphone jack and 20 ohms on the xlr connection.

 

[amirm]

I will review the A30 later. Tonight though, I spent time reviewing the performance of Topping DX7s versus Audio-gd NFB-27.38. I will report that in a day or two. But for now, I really like the sound of the DX7s headphone output.

 

[VanNeumann]

Thanks Amir. First, Happy Spring (Nowruz) to you and all the other members who celebrate the arrival of Spring. I look forward to your insights. Cheers.

 

[bhigh]

Oh , I don't have one. There are pictures of the a30's pcb on the topping website. Yea, it has 10 ohm output impedance on the normal headphone jack and 20 ohms on the xlr connection.

The TPA6120 basically requires 10 Ohm output impedance. From the tech docs: "The series output resistor should be between 10Ω and 100Ω." In fact, most of the examples use a 39.2 Ohm output resistor.

It might be possible to lower the output impedance with very careful board layout since the specs also mention that the minimum load impedance is 8 Ohm, which should be provided by even BA IEMs.

 

[junki]

I know a few members have had the Topping A30 and Dx7/Dx7s. Any thoughts on the sound and build quality of the amps or amp portion of the Dx7/Dx7s?

These days, there are many high quality, competitive priced amps of both discrete and IC topologies with output impedance <1 ohms. Topping basically slaps on the TPA6120's and calls it a day. This results in their amps not being suitable for headphones under 80 ohms in SE and 160 ohms in XLR. Otherwise, your dynamic headphones will be overdampened in swaths of frequencies (and not others) and sound flabby. Planar impedance are usually flat on the frequency domain, so you won't get this effect, but planar impedance are usually low (~20-40 ohms), which, say, paired with an output impedance of 20 ohms XLR means that up to half of the amp's output energy is dissipated before reaching the headphones. This overdampening effect across all frequencies results in anemic attack and long impulse decay at the signal level. How this signal characteristic translates to what you hear depends on the mechanical aspects of your transducer and earcups.

For me, I would never spend my own hard-earned moola on solid state amps that have more than 2 ohm output impedance, and I prefer something much less than 1. This is why I personally would never recommend the DX7 or the A30. If you like Topping for their DACs, the D10, 30, and 50 are great value DACs.

 

[VanNeumann]

These days, there are many high quality, competitive priced amps of both discrete and IC topologies with output impedance <1 ohms. Topping basically slaps on the TPA6120's and calls it a day. This results in their amps not being suitable for headphones under 80 ohms in SE and 160 ohms in XLR. Otherwise, your dynamic headphones will be overdampened in swaths of frequencies (and not others) and sound flabby. Planar impedance are usually flat on the frequency domain, so you won't get this effect, but planar impedance are usually low (~20-40 ohms), which, say, paired with an output impedance of 20 ohms XLR means that up to half of the amp's output energy is dissipated before reaching the headphones. This overdampening effect across all frequencies results in anemic attack and long impulse decay at the signal level. How this signal characteristic translates to what you hear depends on the mechanical aspects of your transducer and earcups.

For me, I would never spend my own hard-earned moola on solid state amps that have more than 2 ohm output impedance, and I prefer something much less than 1. This is why I personally would never recommend the DX7 or the A30. If you like Topping for their DACs, the D10, 30, and 50 are great value DACs.

Junki, I agree with you on th issu s with higher output impedance amps. What are some of the other low impedance amplifiers that you like?

 

[junki]

Junki, I agree with you on th issu s with higher output impedance amps. What are some of the other low impedance amplifiers that you like?

You're not going to like how this ends.

At my level of Google-fu, I can uncover too few amps that have thorough measurements to accompany consistent subjective impressions from individuals who have first-hand experience with a swath of equipment. For the goal of holding as many variables constant, you'd want thorough measurements performed under consistent parameters, and you'd want the same human with relatively known preferences who has heard a bunch of stuff to offer his thoughts on sound. This is why Tyll's work with headphones on InnerFidelity is so valuable.

It's been a minefield out there for me. Some Chi-fi amps publish superb THD ratings @ 300 or 600 ohm loads, but reviewers find their distortion increases drastically under low impedance loads, so the dearth of measurements out there the like of what Atomicbomb does (consistent level into consistently 30 ohm and 300 ohm loads with consistent measuring equipment under consistent parameters, for each output option of the amp) makes things really hard to say. And AFAIK, Atomicbomb really hasn't measured a lot of stuff, as he only measures his own equipment that he intends to use.

So, the only amps I've found with both people who've heard lots of equipment saying they sound nice and measurements to support good technical implementation are the Schiit Jotunheim and the now incredibly unavailable Alex Cavalli Liquid Crimson. I haven't seen measurements for the Rupert Neve RNHP, but Jude put it to use for a stint as their official amp in their headphone measurement setup because he said it measured so well. I have high confidence that all the THX AAA amps will blow everything out of the water on the measurement side, but I haven't heard anything about what the affordable ones (Monoprice and Massdrop) sound like because they're not released.

That's all I got.

Personally, I've been looking for a new DAC and AMP. I'm still undecided between the SDAC and the D50 as my DAC, and I'm at a loss for my amp. I'd choose the Jotunheim, but if I were to get a balanced amp, I'd need it to be bridged so I can use the RCA inputs, and the Jotunheim AFAIK is not bridged.

 

[amirm]

The Schiit Magni 3 has a low output impedance. Here is a sorted chart of headphone output impedances I have measured:

Yes, there is a new product whose review is coming shortly.

I have more headphone amps to review including the JDS Labs objective one.

 

[Jimster480]

Can't wait for that A30 review
I personally love my A30 and use it like all day every day.

 

[mi-fu]

So, the only amps I've found with both people who've heard lots of equipment saying they sound nice and measurements to support good technical implementation are the Schiit Jotunheim and the now incredibly unavailable Alex Cavalli Liquid Crimson. I haven't seen measurements for the Rupert Neve RNHP, but Jude put it to use for a stint as their official amp in their headphone measurement setup because he said it measured so well. I have high confidence that all the THX AAA amps will blow everything out of the water on the measurement side, but I haven't heard anything about what the affordable ones (Monoprice and Massdrop) sound like because they're not released.

That's all I got.

Personally, I've been looking for a new DAC and AMP. I'm still undecided between the SDAC and the D50 as my DAC, and I'm at a loss for my amp. I'd choose the Jotunheim, but if I were to get a balanced amp, I'd need it to be bridged so I can use the RCA inputs, and the Jotunheim AFAIK is not bridged.

Hi Junki, how about the Arcam rhead from your signature? I guess it should have a relatively low impedance too?

 

[Jimster480]

Hi Junki, how about the Arcam rhead from your signature? I guess it should have a relatively low impedance too?

Yea its a 0 impedance amp too.

 

[Xyrium]

Can't wait for that A30 review
I personally love my A30 and use it like all day every day.

Me too! I have an A30 powering my Beyer 880/600s, and it works well. I'd like to see how measurements of this popular brand are stacking up to my listening impressions!

 

[amirm]

I am sorry I keep forgetting to test the A30. To make up a bit for it, here is a quick comparison against JDS O2:

As you see, it has more power but more noise. Distortion is the same as O2 except that the A30 has much more power.

Alas, it has high output impedance (27 ohms). So needs a headphone with high impedance or flat frequency response. Otherwise the frequency response of the headphone will be modified which may be for the better or worse.

 

[Jimster480]

I am sorry I keep forgetting to test the A30. To make up a bit for it, here is a quick comparison against JDS O2:

View attachment 14508

As you see, it has more power but more noise. Distortion is the same as O2 except that the A30 has much more power.

Alas, it has high output impedance (27 ohms). So needs a headphone with high impedance or flat frequency response. Otherwise the frequency response of the headphone will be modified which may be for the better or worse.

Wow what a tease you are

http://en.tpdz.net/products_detail/productId=29.html

If the THD is that high... this will be the first Topping Product to not come close to its specs!

 

[Grave]

Did you use the small headphone output for those measurements? That one is supposed to be 30 ohms.

 

[amirm]

Did you use the small headphone output for those measurements? That one is supposed to be 30 ohms.

Yes I did. Is the larger jack different?

 

[Jimster480]

Yes I did. Is the larger jack different?

The larger one is 10ohm like the DX7.