• 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.

Measurements of Gustard P26 Preamplifier

WolfX-700

Addicted to Fun and Learning
Forum Donor
Joined
Jul 26, 2019
Messages
530
Likes
4,382
Location
China
More than a month ago, an old friend asked me, would you measure a Gustard P26 preamp?In fact, I didn't know Gustard was going to launch this product until he asked me.I then contacted Gustard, who said at the time that P26 had not been officially completed. After the official release, I will send me a retail version for measurement.

Just a few days ago @Max Also ask me if I will measure this unit?In fact P26 was on the road the next day.

Today I got the P26, and the measurement took me a lot of time. Because the preamplifier is very different from the DAC, there is basically no SOP at all. If there are any shortcomings in the following measurements, if you want to know something else, please let me know.

Look at things first:

Front.jpg


Rear.jpg


Actually I always wanted a decent preamp

In fact, I always wanted a decent preamp, but the tragic fact is that it is almost full of garbage (maybe I didn't find it) under $ 1,000. It is not just a defect in the measurement data, but a question of completion.

What I mean by completeness refers to the appearance, function (input and output interface), operation friendliness, function implementation results (such as noise when switching volume), and even the ability to clearly show what you want What you know (input, output, volume, etc.)

This even forced me to do a preamp to achieve what I wanted.But although I realized most of what I wanted, it still couldn't satisfy me. Because the interior is composed of various small modules, and some modules are purchased (such as input and output switching and display), it cannot be said to be a "finished product" at all, but only a "usable" thing
And the cost of making it is close to $ 1,000 (not including the time I spent!!)

And Gustard's long-term adherence to the discrete voltage amplifier circuit has made me have a little more expectations for the sound of this preamp.

Well, don't talk nonsense. Measure it!

NormalXLR.jpg

Update: Left channel PS Noise issue has been fixed and the manufacturer has been notified of the fix. Since repairs do not require costs, manufacturers will immediately produce to new standards. :
PSNFix.jpg




NormalRCAOut.jpg


RCAtoRCA.jpg

RCAtoXLR.jpg


We can see that there seem to be two sets of very different input stages. One is responsible for the input of the balanced signal, and the other is responsible for the input of the unbalanced signal.

In fact, I also got this information from the developer, and the circuit of unbalanced input will also be used for "input gain + 6db setting". This means that the input gain +6 will also affect some basic measurement results in the same way as above.
Fortunately, we generally do not need a large input gain. And if you really feel that the sound is too low (this preamp is actually close to 0db gain by default) you can start "output gain +6" Settings ---- This function does not affect the basic measurement results.

O+6.jpg


I+6O+6.jpg


Dynamic-Range---10Vrms-in-XLR.jpg


The following measurements were made at XLRin XLROut 4VRMS:

First and foremost: volume control:
Volume.jpg


Channel-Balance.jpg


SINAD--_Level.jpg


You can see that the volume control is very linear and the channel balance (green line) is very good. At the same time, the effect of volume adjustment on SINAD is minimal. The disadvantage is that the limit value of the volume control (-60db)may not be low enough in some cases.

Output impedance:
OutIm.jpg



THD+N Vs Freq:

THD+N-Ratio-XLRin.jpg

THD+N-Ratio(200K).jpg


Relative-Level-(1.jpg


IORMS-Level.jpg


SMPTE-Ratio.jpg

CCIF-Ratio.jpg


DIM-Ratio.jpg


Multitone@4VRMS.jpg




All of the above, I think for a preamp of less than $ 700, it is very, very, very good.

I've measured DACs from Gustard before, and to be honest, I'm a little disappointed-let's say the A22 finally achieved the result with double 4499.

I also said that Gustard's insistence on discrete output stages may be the main reason that affects the measurement results of their products.

But on this product today, I really have nothing to say.

A low-cost, high-performance, good-looking preamp. Sorry I have never met before.

What's past is prologue. The future can be expected.
 
Last edited:

Xulonn

Major Contributor
Forum Donor
Joined
Jun 27, 2018
Messages
1,436
Likes
4,098
Location
Boquete, Chiriqui, Panama
$699 on eBay, free shipping from Hong Kong to USA. Unfortunately, I don't need a preamp any more with only digital sources.

Gustard P26-1.jpg

Gustard P26-3.jpg
 

rodtor

Member
Forum Donor
Joined
Aug 21, 2019
Messages
91
Likes
138
Location
Toronto
This is a good point. Are there other reasons for using a preamp now if one has a good DAC-power amp combination, with compatible voltage levels?
 
Last edited:
OP
WolfX-700

WolfX-700

Addicted to Fun and Learning
Forum Donor
Joined
Jul 26, 2019
Messages
530
Likes
4,382
Location
China
I wonder why RCA input has so much higher distortion than XLR input, normally both should be almost same with XLR having advantage in CMRR.

In order to save costs or for other reasons, the developers seem to have decided to use the same circuit for both input gain and unbalanced-balanced conversion.
 
  • Like
Reactions: wje

bunkbail

Senior Member
Forum Donor
Joined
Feb 27, 2018
Messages
483
Likes
588
Meh. Schiit Freya S is better than this.
 

Matias

Major Contributor
Forum Donor
Joined
Jan 1, 2019
Messages
2,770
Likes
4,692
Location
São Paulo, Brazil
Very nice! Would love to see the same measurements of a Schiit Freya S for comparison.
 

Imran Zafar

New Member
Joined
May 13, 2018
Messages
4
Likes
5
Not much detail about features on eBay. Can the RCA input be configured at HT Bypass with XLR out?
 
OP
WolfX-700

WolfX-700

Addicted to Fun and Learning
Forum Donor
Joined
Jul 26, 2019
Messages
530
Likes
4,382
Location
China
Update: Left channel PS Noise issue has been fixed and the manufacturer has been notified of the fix. Since repairs do not require costs, manufacturers will immediately produce to new standards.

PSNFix.jpg
 

Max

Member
Forum Donor
Joined
Mar 8, 2019
Messages
69
Likes
56
Location
France
Great work, good review, thanks a lot @WolfX-700 ! A good preamplifier in low/mid-budget price, nice to see !
 

Max

Member
Forum Donor
Joined
Mar 8, 2019
Messages
69
Likes
56
Location
France
I'm surprised (in a good way) by the near perfect amplitude match between the left and the right channels. Impressive.
 
Last edited:

Veri

Master Contributor
Joined
Feb 6, 2018
Messages
8,062
Likes
9,822
Update: Left channel PS Noise issue has been fixed and the manufacturer has been notified of the fix. Since repairs do not require costs, manufacturers will immediately produce to new standards.

Great contribution btw, @WolfX-700
 

Cortes

Active Member
Joined
Apr 13, 2019
Messages
291
Likes
337
I apologize by the silly question (I've the intuition that it is), but what this thing is useful for?. It's not that any decent DAC with volume control can do the same?.
 

Veri

Master Contributor
Joined
Feb 6, 2018
Messages
8,062
Likes
9,822
I apologize by the silly question (I've the intuition that it is), but what this thing is useful for?. It's not that any decent DAC with volume control can do the same?.
It's purely analog for one, so plays well with powerful poweramps. If you rely on digital control and accidentally blast at max volume, your speakers might fry.

Expensive pre-amps also have very accurate steps within the volume control as has been measured here.
 
Top Bottom