Audio GD SA-31 head amp/ preamp . A powerfull Head Amp with Diamond Difference design .
Apr 4, 2015 at 4:45 PM Post #407 of 444

Utopia

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I've had the SA31 and currently have a Gustard H10, which is supposed to be very similar ot the V200. I never had the amps side by side, so it's difficult to compare them, but the SA31 definitely had a larger soundstage and sounded a little bit leaner and faster IMO. The H10 is warmer, more intimate, with great tone and musicality, but also a bit closed-in compared to the SA31.
 
May 31, 2015 at 6:38 PM Post #408 of 444

conquerator2

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The new audio-gd 'budget' amp - http://audio-gd.com/Pro/Headphoneamp/NFB1AMP/NFB1AMPEN.htm
As well as a super budget one - http://audio-gd.com/Pro/Headphoneamp/NFB3AMP/NFB3AMPEN.htm
 
Jul 5, 2015 at 10:06 PM Post #410 of 444

borrego

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I just bought a SA-31SE from audio-gd's France reseller (220V version). With the on going EUR-USD exchange rate, it costs almost the same as buying from audio-gd originally, but including shipping.
 
I was also considering the C2 11th anniversary edition, but decided to try the last remaining Toshiba BJT diamond differential amp from audio-gd while it can still be found. One might feel regret not doing so as an upcoming amp from another manufacturer with similar topology will cost 110% more to the SA-31SE.
 
Jul 5, 2015 at 11:13 PM Post #411 of 444

conquerator2

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I just bought a SA-31SE from audio-gd's France reseller (220V version). With the on going EUR-USD exchange rate, it costs almost the same as buying from audio-gd originally, but including shipping.

I was also considering the C2 11th anniversary edition, but decided to try the last remaining Toshiba BJT diamond differential amp from audio-gd while it can still be found. One might feel regret not doing so as an upcoming amp from another manufacturer with similar topology will cost 110% of the SA-31SE.


Good choice! I love mine.
What upcoming amp are you talking about?
 
Jul 6, 2015 at 12:08 AM Post #412 of 444

borrego

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Good choice! I love mine.
What upcoming amp are you talking about?

 
I don't feel like stating the brand/model directly because I was on the waiting list buying that amp. That amp shall be Class A all the way, and with an outboard power supply. It was just the lack of low gain option of that amp turned me away. I do think the relay-based volume control of the SA-31SE will have an edge on channel separation though.
 
The SA-31SE will be my "power" headphone amp to drive my HE-500, or may be the T1. For all other higher sensitivity headphones I am extremely satisfied with my EPA-007.
 
Jul 6, 2015 at 12:23 AM Post #413 of 444

conquerator2

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I don't feel like stating the brand/model directly because I was on the waiting list buying that amp. That amp shall be Class A all the way, and with an outboard power supply. It was just the lack of low gain option of that amp turned me away. I do think the relay-based volume control of the SA-31SE will have an edge on channel separation though.

The SA-31SE will be my "power" headphone amp to drive my HE-500, or may be the T1. For all other higher sensitivity headphones I am extremely satisfied with my EPA-007.


Ok. Only the Cavalli comes to my mind :)
 
Jul 8, 2015 at 1:16 AM Post #414 of 444

borrego

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Jul 10, 2015 at 5:26 AM Post #415 of 444

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Just received my SA-31SE in the office. Surprising, it comes with the optional aluminum remote control. It could the aluminum remote is a standard accessory from the French reseller.
 
First thing I do is opening up the case and remove all the "Input Short" jumpers behind the input relays. I will be connecting the SA-31SE to my NFB-1 in parallel to the EPA-007 at home. I don't want the input short jumpers to affect my EPA-007.
 
I am just doing some initial listening with my SR325e in the office. The overall tone is very similar to my 5751 + 832A tube amp. The SA-31SE does resolve better compare to the tube amp. The treble is beautiful, bass is a bit light (but does extend very good). I shall burn in longer period and see if bass will improve.
 
Overall I am happy with my purchase.
 
Jul 10, 2015 at 11:14 AM Post #416 of 444

CJG888

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Try it with the DT48e, if you can find a pair. This is a fantastic combination for jazz and classical.
 
Jul 12, 2015 at 2:07 PM Post #417 of 444

borrego

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A FIX SHOULD BE DONE FOR EVERY SA-31!!!
 
I have owned the SA-31SE for a few days. While I like its sound, I do find a few problems with my unit:
 
1. The amp takes a long time to "warm up": I find it needs up to 2 hours to have its sound signature to settle down. And it is with my EPA-007 stacking over it
2. Even after warm up, it sounds lean. The bass and overall dynamic lack quite a bit
 
I know the SA-31 circuit is base on the discontinued/earlier audio-gd SA100/SA100i/SA200 integration amp. I recall reading something before from audio-gd's Chinese DIY forum saying there is usage of temperature compensation transistors in the SA300 poweramp circuit design (the SA300 is the balanced version of the SA100/SA200). The temperature compensation transistors should be placed/pressed to the headsink shared by the output power transistor.
 
I start looking at the SA-31 photos on audio-gd websit, and find the SA-31 also has a pair of this temperature compensation transistors (circled yellow below):
 

 
 
Thus I suspect the problems I have the SA-31 is because of improper contact between the temperature compensation transistor and the aluminum back plate heatsink shared with the output power transistors.
 
I come up with the following "Laundry Clip Fix" for my SA-31: a fix to press the temperature compensation transistor properly against the aluminum back plate. I use all plastic parts to make sure it won't short any circuit by accident.
 
Step 1: Take out the plastic spings from a pair of laundry clips I have at home (these are laundry clips I bought from Ikea)


 
Step 2: Find a pair long/sturdy piece of plastics serving as the "pressing levers". I cut off the tails of a pair of plastic forks I have at home.

 
Step 3: Place all the parts I made to press/clamp the pair of temperature compensation transistors against the aluminum black plate. I apply glue between the plastic clips and the top of the black plate to make sure the clips stay put.

 
 
Results after the fix:
1. The amp now only needs about 20mins to "warm up" and have the sound signature stabilized.
2. More bass, and more dynamic sounding signature. My SA-31 finally sounds "properly".
 
I strongly recommend all SA-31 owners to apply the fix.
 
Jul 13, 2015 at 10:40 AM Post #418 of 444

Robert777

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  A FIX SHOULD BE DONE FOR EVERY SA-31!!!
 
I have owned the SA-31SE for a few days. While I like its sound, I do find a few problems with my unit:
 
1. The amp takes a long time to "warm up": I find it needs up to 2 hours to have its sound signature to settle down. And it is with my EPA-007 stacking over it
2. Even after warm up, it sounds lean. The bass and overall dynamic lack quite a bit
 
I know the SA-31 circuit is base on the discontinued/earlier audio-gd SA100/SA100i/SA200 integration amp. I recall reading something before from audio-gd's Chinese DIY forum saying there is usage of temperature compensation transistors in the SA300 poweramp circuit design (the SA300 is the balanced version of the SA100/SA200). The temperature compensation transistors should be placed/pressed to the headsink shared by the output power transistor.
 
 

Thank you for the above post. The information is very useful but it is things like this that may make me return my SA-31SE when I receive it this week.
I was really excited for my new amp but I am now a little apprehensive. I am rubbish with all kinds of DIY and I prefer things to work as intended from the start.
 
Has anybody else had a similar experience?
 
Cheers.
 
Jul 13, 2015 at 11:10 AM Post #419 of 444

conquerator2

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No. It is an awesome amp. No mods needed imo
 

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