• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

Topping L30 Headphone Amplifier Review

boXem

Major Contributor
Audio Company
Joined
Jun 19, 2019
Messages
2,018
Likes
4,899
Location
Europe
M400 RCA output supposedly have buffer but they fked up the LPF. It pairs with E30 and D10s so no issue from my point of view. 2.5K is low in your book. But higher than 600ohm means high to me.
Seriously? You achieved engineering excellence on the performance side, and I sincerely admire what you did there (even a bit jealous tbh).
But you can't just say that since it pairs well with two of your employer's current offerings your job is done.

600 ohms is high in the mind of somebody designing an headphone amp, somebody designing a line output stage is expecting much more.
 

Bamboszek

Active Member
Joined
Mar 17, 2018
Messages
181
Likes
306
It's all about engineering choices and compromises. Potentially you can place buffer in front of pot like in o2. That might degrade noise and SINAD a bit in exchange for higher and constant input impedance.
I can agree that ordinary customer shouldn't worry about impedances and etc. but if you want absolute best performance it's really hard to design one size fits all amplifier. Especially when in same time you try to squeeze every dollar and dB of performance.
Like I said before, for me it is OK as long you pair TOTL amp with TOTL DAC. Most important thing that device needs to be safe for headphones. Absolutely no DC at output and stability under all realistic conditions.
 

JohnYang1997

Master Contributor
Technical Expert
Audio Company
Joined
Dec 28, 2018
Messages
7,175
Likes
18,298
Location
China
Seriously? You achieved engineering excellence on the performance side, and I sincerely admire what you did there (even a bit jealous tbh).
But you can't just say that since it pairs well with two of your employer's current offerings your job is done.

600 ohms is high in the mind of somebody designing an headphone amp, somebody designing a line output stage is expecting much more.
I value interference rejection more. The cable can pick up a lot of noises. Also majority of products on the market have 100 ohm output impedance. If you have higher output impedance, all you can lose is a bit of volume. If the output filter transfer function is depending on the downstream input impedance, then it's a fail product.
 

NDC

Member
Joined
Jul 18, 2020
Messages
86
Likes
115
Location
Sydney, Australia
I'm almost tempted to get another L30 instead of an A90 to match my D90 given the performance! Wow @JohnYang1997 this is incredible performance at the price...
 

3125b

Major Contributor
Joined
May 18, 2020
Messages
1,357
Likes
2,216
Location
Germany
True, but JohnYang said they had implemented a qc process to insure better channel matching. They probably won't all be perfect like this, but good enough. With the available gain options, it's not that much of a problem.
 

boXem

Major Contributor
Audio Company
Joined
Jun 19, 2019
Messages
2,018
Likes
4,899
Location
Europe
I value interference rejection more. The cable can pick up a lot of noises. Also majority of products on the market have 100 ohm output impedance. If you have higher output impedance, all you can lose is a bit of volume. If the output filter transfer function is depending on the downstream input impedance, then it's a fail product.
We are on the same line here but I had something else in mind.
If you have an output buffer to design while chasing THD+N, you know better than I do that the lower the feedback resistors value, the lower the N, but the higher the output current, which means higher THD (for the same amount of feedback). So a compromise has to be done while assuming a typical load.
If the requirement is best ASR SINAD, target load will be the AP555 input impedance, i.e. 100k.
Real word matching requirement would be something like 20k to 50k.
I am maintaining that 2.5k is low.
 

JohnYang1997

Master Contributor
Technical Expert
Audio Company
Joined
Dec 28, 2018
Messages
7,175
Likes
18,298
Location
China
We are on the same line here but I had something else in mind.
If you have an output buffer to design while chasing THD+N, you know better than I do that the lower the feedback resistors value, the lower the N, but the higher the output current, which means higher THD (for the same amount of feedback). So a compromise has to be done while assuming a typical load.
If the requirement is best ASR SINAD, target load will be the AP555 input impedance, i.e. 100k.
Real word matching requirement would be something like 20k to 50k.
I am maintaining that 2.5k is low.
It's fine. Ap does have selection of 300 600 and 100k ohm load selection tho. But imo irrelevant to the point. 2.5k is relatively low among different products, yes.
 
Top Bottom