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New Sabaj a10h a Worthy Topping L30 Competitor?

GGroch

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#1
Sabaj has released a trio of a10 series products including the very interesting a10h desktop headphone amplifier for $120 that promises excellent performance and a few step up features for a modestly priced single ended hpa:
Specs:
- 125dB THD+N and 131dB dynamic range (scroll down the page for graphs)
- 2W(16), 1W(32), 500mW(300) and 250mW(600) output.
- Near Zero output impedance.

Features:
-3 gain settings (-6. 0, 9)
- Pre-Amp output with volume control independent of headphone volume
- 256 level digital volume control
- full function remote that also controls the a10d DAC and a10a speaker amp.

If functions and specs as close to what is promised the a10h has got the L30 beat in high impedance power, a few slick features, and price. Equal in cuteness. They appear to be in stock through the normal places including Amazon 3rd party. I hope to see one tested asap.
Sabaj a10h.jpg
 
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solderdude

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#2
Same gain issue as L30.

The given specs cannot be used with most DACs that put out 2Vrms.

In 300 ohm there is no 500mW only 100mW
in 600 ohm there is no 250mW only 50mW

using the A10D DAC with its 3V output this increases to 230mW in 300 ohm and 110mW in 600 ohm

The reason is the +9dB high gain setting.
To reach the quoted output levels you will need a DAC that reaches 4.37V.

There has to be a DCDC converter inside that converts the incoming 15VDC to +/- 18V DC for the specs to be reached.

47k input R instead of 2.5k ohm.
 
OP
GGroch

GGroch

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Thread Starter #4
I see the Sabaj a10d DAC has max 3v output in variable mode. I never found the L30's output a practical problem in use, however, did make the listed specs questionable, and it is certainly possible the a10d's specs are suspect. Good reason for testing.

The L30's advantages include physical buttons for power, pre-out, and gain. I do see a dedicated gain button on the a10h remote. The a10h "relay"** volume could allow gain changes to be less frequent.

**The specs refer to a "relay" volume control which I assumed meant digital, but what is a relay control and what is the tie to the 2 amp modes, Pr0 and Pr1?
 
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Veri

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#6
@solderdude So can we feed the amp via balance DAC using XLR to RCA connector?
No.. XLR to RCA cable or adapter can only carry half the voltage of the XLR signal. You lack the necessary pins for full voltage transfer. A way around that is a universal buffer (or a high quality transformer, example). So yet another thing in between DAC and amp.
 

VintageFlanker

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#7
What @solderdude said. The announced power is virtually unreachable with regular unbalanced DAC. Even the ADI-2 DAC max output is only ≈3.45Vrms through RCA.

Still, this is a cool offering and an interesting alternative to the mighty L30. Especially when it comes with digital volume control and a remote. Then, this should be a viable budget preamp/headamp solution.
 

Racheski

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#9
Strange pricing on the a10d DAC ($260) compared to the matching a10h amp ($130). I can't think of another stack where the DAC is 2x more expensive than the amp. Topping e30 is $150, but Sabaj a10d has Bluetooth and a slightly better AKM chip (4497 vs 4493). Hopefully Amir can get the full stack for measurements :)
 

solderdude

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#10
You pay $150 for 2V out so by logic you pay 1.5x more for 3V out = $ 225.- then add $ 35 for BT and you're there :D
 

Veri

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#12
I thought this looked bizarre for an analog product. But it’s actually a relay-switched resistor network and the only ‘digital’ element is the control circuitry.
In a way it's a nice cute relay resistor headphone amp, but the performance won't be on L30 level. Most of the real estate is used for the volume control after all. The head-amp looks like a very basic TPA6120A2 implementation with what looks like a NE5532 buffer(?), no feed-forward/nested feedback for lowest distortion? I mean it's probably 'fine' but not comparable performance level that begun with the THX AAA stuff.
 
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solderdude

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#13
I think it has 2 TPA6120A2 sections in parallel like L30 (1 chip/channel) doubling the output current capabilities.
The near 0 ohm looks like the feedback is coming from behind the obligatory resistors.
Would like to see it tested with some more exotic loads to see if it remains stable.

a difference with L30 is that the RCA output has it's own volume control setting.
I assume the last volume control setting is remembered for both modes.
This is a neat feature when switching between active monitors (volume controlled by A10h) and headphones.
The rather L-R matching problem free volume control (with remote) and display showing attenuation also is a good idea.
Too bad high gain is just +9dB (2.8x)
 

charleski

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#14
In a way it's a nice cute relay resistor headphone amp, but the performance won't be on L30 level. Most of the real estate is used for the volume control after all. The head-amp looks like a very basic TPA6120A2 implementation with what looks like a NE5532 buffer(?), no feed-forward/nested feedback for lowest distortion? I mean it's probably 'fine' but not comparable performance level that begun with the THX AAA stuff.
I think the problem that manufacturers face these days is that there's very little left to accomplish in order to differentiate from the competition. Chinese makers are to be praised for their efforts to bring SOTA performance to both DACs and high-powered headphone amps at a reasonable cost, but there's really no way to get them any cheaper in this form.

The only thing left is features and frills. Personally, I'd be prepared to pay extra for an amp with cool, glowy, analog VU meters (with adjustable sensitivity), but that might be too niche.
 

liu

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#15
very likely it's a composit feedback that the 1612 is hidden below the relay board.

for what is visible on the images, it is almost exactly the same as the L30 layout --- it even have the exactly same zobel network and dc/over current protection as the L30. no reason why other parts hidden elsewhere are not the same.

I reverse engineered the L30 circuit so I know how similar they are: https://www.audiosciencereview.com/...ne-amplifier-review.15226/page-35#post-496552

The head-amp looks like a very basic TPA6120A2 implementation with what looks like a NE5532 buffer(?), no feed-forward/nested feedback for lowest distortion?
it's not! watch closely, the relay module is mounted above the bottom pcb. i can't see what's below, but based on what is visible, I'd say it's an exact copycat of L30's amp circuit and protection circuit. also same ac coupled design. only power supply and volume are different

ne5532 is the protection circuit. this part is exactly the same as l30 pcb version < 2012.
 
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liu

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#16
omg they really messed it up --- they copied L30 pcb (pre 2012 version) piece by piece, even the protection circuit! BANG! your headphone will explode!


@SMSL-Mandy something is very wrong.

@JohnYang1997 maybe you can teach your competitor how to design it properly:)
 
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Veri

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#17
ne5532 is the protection circuit. this part is exactly the same as l30 pcb version < 2012.
I see, didn't know that. Interesting :)

omg they really messed it up --- they copied L30 pcb (pre 2012 version) piece by piece, even the protection circuit! BANG! your headphone will explode!
You're saying it is a copy of the original <2012 serial no. 'Unsafe' Topping L30??? :oops::oops:
 

solderdude

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#18
The only difference between the old and 2012 version of L30 I see is a slightly changed layout of the protection circuit and a pogo pin.
 

VintageFlanker

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#19
omg they really messed it up --- they copied L30 pcb (pre 2012 version) piece by piece
Wut? Here is supposed to be the A10H board:
Screenshot_20210407-233808_3-min.png

Then the L30:
IMG_6886~2.jpg

@JohnYang1997 maybe you can teach your competitor how to design it properly
Or teach his own team how to design the L30 safely in the first place... :p
 

liu

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#20
Wut? Here is supposed to be the A10H board:
Here's the L30 photo shot by myself:

IMG_6891.jpg


here's the sabaj product flyer:

Screen Shot 2021-04-08 at 17.36.12.png


as you said, at the first glance they seem to differ a lot. but when you grab a magnify glass to see the detail:

for each channel, the topology has the same feedback resistor (the small, 1kohms resistor on topping board), same output resistor (the 3R30 one) and the same Zobel network (4R70 and the capacitor). Topping's design is very very special --- you won't see other 6120A2 to have this kind of design. and both have a thick line to the HP output, and a thin line back to the 1612 (that's what nested feedback means).

topping:
Screen Shot 2021-04-08 at 15.51.54.png


sabaj:
Screen Shot 2021-04-08 at 15.51.11.png



Here's the DC protection circuit, the topping image is the 2006 version, before the 2012 fix:
Screen Shot 2021-04-08 at 15.53.15.png


sabaj:
Screen Shot 2021-04-08 at 15.52.48.png


you see the same DC_Det marking on the pcb board, same N5532 opamp, same resistor value: (note, 01C/01D and 103/104 are the same resistor values. they are both 10k ohms and 100k ohms.) and same diode (T4). If you count them, both have the same number. if you trace down the pcb layout, they are exactly the same.

The 2012 version is different (not shot by me so sorry for the image quality):

Screen Shot 2021-04-08 at 16.03.48.png


so you are now convinced that they f__ked up.
 
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