Sabaj A20h Balanced Headphone Amplifier Owner's Thread

[Veri]

FYI, my A20h is on its way to Amir for testing.

Yay! Lovely

 

[bilifen]

My A20h picks up interference, something phone related, either internet or GSM or something like that.
It gets better if I remove my phone (or a GPS Tracker) away from the DAC/ my headphone cable.
Is this Issue related to my Xonar U7 or to the A20H?

 

[Joel]

My A20h picks up interference, something phone related, either internet or GSM or something like that.
It gets better if I remove my phone (or a GPS Tracker) away from the DAC/ my headphone cable.
Is this Issue related to my Xonar U7 or to the A20H?

It has been a while since I used my A20H but when I had it hooked up it was on a shelf where my phone and several other cellular capable devices lived and I never had a problem. I'm *not* saying you're wrong, but I'd check the U7 or cabling first. Perhaps run the A20H off another source and see if the problem persists.

 

[Filio45]

My A20h picks up noise if I place my phone directly on top of the amp. Move it a few cms away, just to the side of the amp and it's gone. So it does appear more susceptible than it should be, but not excessively so that it presents a problem as such. Obviously sticking a phone on top of it is not a good idea anyway.

I remember this aspect of its design being questioned quite early on in the A10h review thread, and those concerns appear to have been pertinent
considering a few users on ASR have reported interference issues subsequently.

 

[LegionOfHell]

Output Power: 4W x 2 (16 Ω) 2W x 2 (32 Ω) 1W x 2 (300 Ω) 500mW x 2 (600 Ω)

Are the power ratings for balanced headphone out or unbalanced ?

 

[Joel]

I believe that is balanced.

 

[LegionOfHell]

The A20H will powerfully drive any of the headphones in your signature. I use the HE6se in mid gain and it's plenty loud with great quality.

It probably drives all (except the most demanding headphones) withe ease.

No doubt, But I think Topping L30 II has more juice...for like $50 more...

 

[Roland68]

No doubt, But I think Topping L30 II has more juice...for like $50 more...

Output Power: 4W x 2 (16 Ω) 2W x 2 (32 Ω) 1W x 2 (300 Ω) 500mW x 2 (600 Ω)

Are the power ratings for balanced headphone out or unbalanced ?

The L30 II may actually have a little more power than the A20h in true symmetrical operation, but the L30 II only has a cheap potentiometer with the usual channel deviations, which is also subject to aging.
The A20h has one of the best volume controls with absolute channel equality, relay based with resistors. With other manufacturers, the surcharge for this alone is higher than the purchase price of the A20h. It also has a remote control and real balanced inputs.

The A20h has balanced and unbalanced headphone outputs, 4-pin XLR, 4.4mm Pentaconn, 6.3mm jack and adapter to 3.5mm and the power ratings are for balanced.

 

[ninetylol]

The L30 II may actually have a little more power than the A20h in true symmetrical operation, but the L30 II only has a cheap potentiometer with the usual channel deviations, which is also subject to aging.
The A20h has one of the best volume controls with absolute channel equality, relay based with resistors. With other manufacturers, the surcharge for this alone is higher than the purchase price of the A20h. It also has a remote control and real balanced inputs.

The A20h has balanced and unbalanced headphone outputs, 4-pin XLR, 4.4mm Pentaconn, 6.3mm jack and adapter to 3.5mm and the power ratings are for balanced.

I think someone just looking at power figures will not understand

 

[Roland68]

I think someone just looking at power figures will not understand

What use are numbers on paper to me?
I had compared the L30 II with the old L30, the A20h, my old Violectric V100 and the Singxer A1 and it had no advantage in terms of sound, even though I had Amirm's test in mind.
So I gave it back.
My AKG K812, my Hifiman Sundara and also the Fostex with the foil drivers don't need a lot of power, I operate them on the low gain level for all HPAs. Of course, if you want to operate a Hifiman Susvara, HE6se or similar, ok, but the performance of the L30 II may then be too tight.

 

[LegionOfHell]

The L30 II may actually have a little more power than the A20h in true symmetrical operation, but the L30 II only has a cheap potentiometer with the usual channel deviations, which is also subject to aging.
The A20h has one of the best volume controls with absolute channel equality, relay based with resistors. With other manufacturers, the surcharge for this alone is higher than the purchase price of the A20h. It also has a remote control and real balanced inputs.

The A20h has balanced and unbalanced headphone outputs, 4-pin XLR, 4.4mm Pentaconn, 6.3mm jack and adapter to 3.5mm and the power ratings are for balanced.

I have a Creative X7 which had problems driving my t50rp....loud volume but not enough power(voltage?) to properly drive it..

And the X7 outputs 1.3 watts @ 32ohm.

 

[ninetylol]

What use are numbers on paper to me?
I had compared the L30 II with the old L30, the A20h, my old Violectric V100 and the Singxer A1 and it had no advantage in terms of sound, even though I had Amirm's test in mind.
So I gave it back.
My AKG K812, my Hifiman Sundara and also the Fostex with the foil drivers don't need a lot of power, I operate them on the low gain level for all HPAs. Of course, if you want to operate a Hifiman Susvara, HE6se or similar, ok, but the performance of the L30 II may then be too tight.

I was just saying these amps today have enough power for 99.9% if headphones. So people only looking at power output and nothing else are missing the point of good products.

E.g. relay volume control is awesome. also this one got a remote.

 

[LegionOfHell]

I know this is a A20h thread but I have a question about Sabaj PHA2, since I cannot find any info about Sabaj PHA2 anywere:

Sabaj PHA2 has a 6.5mm headphone output jack which is for high impedance headphones and a 3.5mm jack for lower impedance headphones… I have read that there are two resistors before the 3.5mm jack…

What are the output impedances for each one of the ports(3.5mm and 6.5mm) ? I can’t find anything online…

 

[half_dog]

I know this is a A20h thread but I have a question about Sabaj PHA2, since I cannot find any info about Sabaj PHA2 anywere:

Sabaj PHA2 has a 6.5mm headphone output jack which is for high impedance headphones and a 3.5mm jack for lower impedance headphones… I have read that there are two resistors before the 3.5mm jack…

What are the output impedances for each one of the ports(3.5mm and 6.5mm) ? I can’t find anything online…

I would guess around 10 ohm or higher if it was designed following the recommendations of the tpa6120a2.

 

[LegionOfHell]

I would guess around 10 ohm or higher if it was designed following the recommendations of the tpa6120a2.

the official spec says that this amp is suitable for 8ohm-600ohm headphones though

 

[half_dog]

the official spec says that this amp is suitable for 8ohm-600ohm headphones though

Yep, I have seen the specs that's why what I said was based on the specs of the TPA6120A2. This amp is a "old" design that seems to follow some guidelines of the TPA manual (at least by a quick look) - different from a L30 and copies that take a "bold" approach.

According to the manual an output resistor for each channel is "mandatory" to avoid oscillation of the op amps even more for low impedance headphones.

 

[solderdude]

Output R on the discontinued predecessor PHA1 is 150 ohm on 3.5mm output.

A20d uses the same circuit as PHA2 which is near 0 ohm out (not measured by Amir but Archimago did).

Buy one and drop ship to Amir and ask him to measure Rout from the headphone outs.

 

[half_dog]

Output R on the discontinued predecessor PHA1 is 150 ohm on 3.5mm output.

A20d uses the same circuit as PHA2 which is near 0 ohm out (not measured by Amir but Archimago did).

Buy one and drop ship to Amir and ask him to measure Rout from the headphone outs.

I thought A20D was "inspired" on A10H and this on L30, using a zobel filter at the output.

 

[solderdude]

A20D does have a Zobel (47 ohm load for HF, probably copied from L30) and it looks like the PHA2 has a similar circuit as the HPout of the A20D.
Don't know the output R for the 3.5mm TRS out but it is just a series resistor.

 

[LegionOfHell]

Don't know the output R for the 3.5mm TRS out but it is just a series resistor.

so a series resistor doesn't affect the output impedance ? What would you guess the output impedance is for the 3.5mm headphone out on PHA2 ?

and you are saying the 6.5mm output on PHA2 has the same output impedance as A20d ? What is A20d's output impedance ?