• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required as is 20 years of participation in forums (not all true). Come here to have fun, be ready to be teased and not take online life too seriously. We now measure and review equipment for free! Click here for details.

Review and Measurements of Audio-gd NFB-27.38 DAC and Headphone Amplifier

Nihilion

New Member
Joined
Aug 16, 2018
Messages
3
Likes
0
What do you mean? I have email communication between the unit's owner and Kingwa at Audio-gd repeatedly referring to this unit as NFB 27.38. You are saying the owner doesn't know what he has bought and the seller doesn't know what he sold to him?
I'm sorry I was confused by their naming convention. The NFB 27.38 seems a very different device than the NFB-27, which was the device I'm familiar with. The exterior of the 27.38 looks identical to the Master-9, and has apparently been discontinued.
 
OP
amirm

amirm

Founder/Admin
Staff Member
CFO (Chief Fun Officer)
Joined
Feb 13, 2016
Messages
27,424
Likes
66,792
Location
Seattle Area
Thread Starter #142
DACs. Have we forgotten how to pluralize words? The plural of DAC is DACs, not "DAC's". I mean, did you eat "meatball's" today? Did you take the "dog's" for a walk?
The grammar rules for acronyms/capital letters is different than other words. So your point about dogs and meatballs doesn't apply. "Mind your ps and qs" would be pretty confusing if you mean the usual saying of "mind your P's and Q's."

While it is now the recommended norm to not to add apostrophe to muli-letter acronyms like DACs and DVDs, the usage is so common as not require this kind of retort.
 

Jimster480

Major Contributor
Forum Donor
Joined
Jan 26, 2018
Messages
1,362
Likes
847
Location
Miami
I'm sorry I was confused by their naming convention. The NFB 27.38 seems a very different device than the NFB-27, which was the device I'm familiar with. The exterior of the 27.38 looks identical to the Master-9, and has apparently been discontinued.
Yes they do make it very confusing like that.
 

Thomas savage

Power hungry desperado
Moderator
The Watchman
Forum Donor
Joined
Feb 24, 2016
Messages
9,189
Likes
11,803
Location
uk, taunton
Currently the job of grammar nazi is not available, if such a opening does come up I will be sure to let you all know. Though @Nihilion is enthusiastic he’s clearly got some way to go before we can consider him for the position.
 

RayDunzl

Major Contributor
Central Scrutinizer
Joined
Mar 9, 2016
Messages
9,481
Likes
7,619
Location
Riverview FL
May we make up words as we go along?

"I was not going against setting up a Space Force; what I was against was
rushing to do that before we define those problems..

We've had a year, over a year in defining. And the orbitization of this solution
in terms of institutionalizing forward momentum is very important."

- "Mad Dog" Mattis, defending the reversal of his earlier objections, relating to, I suppose, orbitization.
 

Blumlein 88

Major Contributor
Forum Donor
Joined
Feb 23, 2016
Messages
9,107
Likes
11,887

Blumlein 88

Major Contributor
Forum Donor
Joined
Feb 23, 2016
Messages
9,107
Likes
11,887
May we make up words as we go along?

"I was not going against setting up a Space Force; what I was against was
rushing to do that before we define those problems..

We've had a year, over a year in defining. And the orbitization of this solution
in terms of institutionalizing forward momentum is very important."

- "Mad Dog" Mattis, defending the reversal of his earlier objections, relating to, I suppose, orbitization.
You mean like plankton as an audio quality?

How about anechoic reflection?

Aural cellular resolution anyone?

Then I read something like this from wikipeida:

In the inner ear, stereocilia are the mechanosensing organelles of hair cells, which respond to fluid motion in numerous types of animals for various functions, including hearing and balance. They are about 10–50 micrometers in length and share some similar features of microvilli.

We know what stereo is. So stereocilia are used for hearing and balance. Is that stereo balance they are referring to? Is a microvilli a small villa in Italy? How do we orbitize a solution? Will Elon Musk's Space X become involved?
 

SIY

Technical Expert
Technical Expert
Joined
Apr 6, 2018
Messages
4,566
Likes
9,053
Location
Phoenix, AZ
 

TeddyK

New Member
Joined
Dec 8, 2018
Messages
1
Likes
3
Amirm,

In 2013, a French electronician did a study on the AOP burson used in AUdio-GD products.
The video is here (but in french) :

He did the same conclusion as yours. These AOPs are very very bad. A lot of distorsion and not stable.
 

trl

Major Contributor
King of Mods
Joined
Feb 28, 2018
Messages
1,072
Likes
1,023
Location
Iasi, RO
I measured myself solid-state "opamp-replacement" from BURSON: V5 and V6 and found no flaws. I used RMAA, ARTA and scop. Also, did compared results against regular opamps like NE5532 and similar...depending on the stage used, BURSON was measuring sometimes better, sometimes worse, but most of the times all tested opamps were measuring about the same. E.g.: In I/V stage of PLAY DAC, the V6 showed a tiny little increase of THD, but in GAIN stage of Objective2 I got a tiny little lower background noise (a better SNR).

Under no circumstances V5 or V6 will oscillate, nor induce distortions, at least not in my devices.

The only downsize I found would be the price and the output DC-voltage (this might affect output-DC of some amps or DACs, depending on the design; however, found no issues with all of my tested devices).

I do hope Amir will be able to test the V5 opamps within couple of months. Even if V5 is not in the same league with the V6, I found it a good match for the gain stage of my Objective2 headamp, but also in output buffer of my ASUS Essence One combo; too bad I can't close the top case, so...can't use them.

L.E.: Solid state opamp-replacement are for those people that really don't want opamps in their audio devices. No matter the manufacturer, the schematic is optimized for audio-use only and also for unity gain. However, depending on the internal design of the audio equipment used, there might be incompatibilities, of course. Also, if best measurement numbers are needed, then feel free to choose OPA1612, OPA1652, MUSES8920 or similar; don't use solid-state "opamps".
 
Last edited:

trl

Major Contributor
King of Mods
Joined
Feb 28, 2018
Messages
1,072
Likes
1,023
Location
Iasi, RO
Let's just ignore the RMAA and ARTA tests I've done with Burson's opamps, here's a QA401 during some work: https://www.head-fi.org/showcase/bu...d-opamp-v5i.21562/reviews?page=3#review-18921.

Under some circumstances V5i seems to be better than AD797, but sometimes V5 gets way much better than OPA627 and OPA827. Indeed, the V4 seems to be measuring worse than V5 and V5i (that are measuring worse then the newer V6), but then have a look how the 1V & 20x-gain THD signal looks like on the OPA827 vs. Burson V4: 10dB better on the V4 side.

I really think it's all about the implementation and compatibility here and what's the stage the opamp is used for (I/V, gain, buffer), but poor decoupling will make a huge difference for the solid-state opamps. Nobody will throw on the market a solid-state "opamp replacement" device at such a high price without doing basic tests first.
 
Last edited:

Veri

Major Contributor
Joined
Feb 6, 2018
Messages
4,927
Likes
5,492
Let's just ignore the RMAA and ARTA tests I've done with Burson's opamps, here's a QA401 during some work: https://www.head-fi.org/showcase/bu...d-opamp-v5i.21562/reviews?page=3#review-18921.

Under some circumstances V5i seems to be better than AD797, but sometimes V5 gets way much better than OPA627 and OPA827. Indeed, the V4 seems to be measuring worse than V5 and V5i (that are measuring worse then the newer V6), but then have a look how the 1V & 20x-gain THD signal looks like on the OPA827 vs. Burson V4: 10dB better on the V4 side.

I really think it's all about the implementation and compatibility here and what's the stage the opamp is used for (I/V, gain, buffer), but poor decoupling will make a huge difference for the solid-state opamps. Nobody will throw on the market a solid-state "opamp replacement" device at such a high price without doing basic tests first.
Interesting reviews

"To be honest, comparing the sound quality of Op-Amps is not easy, at least for me. The differences that we need to observe are tiny, and usually, it is more of an accumulation of impressions over time. So please bear in mind that differences described below are in the order of small degree of differences. "

"excellent upgrade in my amp, adds a small amount of warmth"

At least people are admitting the differences seem to be small enough they're not even sure they're there :D
 

trl

Major Contributor
King of Mods
Joined
Feb 28, 2018
Messages
1,072
Likes
1,023
Location
Iasi, RO
Interesting. :) I was only reading the QA401 review and the first one, with the fake MUSES01 (probably purchased from eBay).

By ears only, the easiest differences to spot are the background noise and channel imbalance. For the first one I apply some more gain at the output (I use Objective2 with 3/5X of gain, or even more, if DUT is a DAC) and for the last one, I usually A/B test against a well-known device or, where possible, I swap opamps between the 2 channels and see if the stage moves in the other side.

Of course, ears can be misleading, so I do use ARTA, RMAA and PicoScope. :)
 
Top Bottom