[Apos Audio]

Hi all,

We’re thrilled to introduce the xDuoo TA-66, an OTL headphone tube amp that merges classic engineering with the convenience of modern components. Rather than use a PCB, this amp uses point-to-point wiring, a traditional technique that connects every component together with copper wiring. This old-school engineering method paired with modern amenities like a step-by-step volume potentiometer results in an amp that revives the spirit of golden-age tube amps with a contemporary sensibility.

Product highlights

• 6N2 tube for the pre-amp stage
• 6N5P tube for the buffer stage
• Point-to-point wiring for minimal interference and pure sound
• Step-by-step volume potentiometer for precise volume control
• Aux out preamp for enhanced sound quality in your audio system
• Professional-grade resistances and capacitors for uncolored sound
• Solid aluminum alloy shell and sandblasted texture panel for durability and interference

Here's the link to the blog for more info: https://apos.audio/blogs/news/meet-the-xduoo-ta-66-otl-tube-headphone-amplifier

 

[Loftprojection]

Nice little amp, congrats.

Any plans for an upscale Apos headphone tube amp that would be delivered with your Ray 12AU7-6SN7 in the future?

 

[Menkau-ra]

How is the noise floor compared to TA-26?

 

[dxanex]

Reminds me of a modernized DarkVoice 336se. Looks great!

 

[chaotic_angel]

I am wondering what will be the best pair tubes for oowey goowey syrupy sound on this bad boy...

 

[chaotic_angel]

Hi all,

We’re thrilled to introduce the xDuoo TA-66, an OTL headphone tube amp that merges classic engineering with the convenience of modern components. Rather than use a PCB, this amp uses point-to-point wiring, a traditional technique that connects every component together with copper wiring. This old-school engineering method paired with modern amenities like a step-by-step volume potentiometer results in an amp that revives the spirit of golden-age tube amps with a contemporary sensibility.

Product highlights

• 6N2 tube for the pre-amp stage
• 6N5P tube for the buffer stage
• Point-to-point wiring for minimal interference and pure sound
• Step-by-step volume potentiometer for precise volume control
• Aux out preamp for enhanced sound quality in your audio system
• Professional-grade resistances and capacitors for uncolored sound
• Solid aluminum alloy shell and sandblasted texture panel for durability and interference

Here's the link to the blog for more info: https://apos.audio/blogs/news/meet-the-xduoo-ta-66-otl-tube-headphone-amplifier

I am wondering what is under the metal plat? a PCB?

 

[Wiljen]

I do wonder about the choice of the 6N2 (12aX7) as the pre-amp as it has unusually high gain for a pre and usually they are avoided in this role as with bandwidth of only 10k and a mu of 100 it is likely to suffer from miller capacitance and some audible roll-off.

Is the Ta-66 designed to allow a step down to a 12AT7 in the pre-amp instead of the 12AX7 if a lower gain is needed? I Would expect that in order to handle a lower plate resistance of the 12AT7 (11k vs 63k) it would need a different coupling cap to the plate resistor and more current available from the power supply than would be needed to power the 12AX7. My thought is if it were designed for a 12AT7, then a 12AX7 should drop in and draw less current than anticipated and not cause an issue, but if it was designed for a 12AX7 from the outset, swapping in a 12AT7 might stress the power supply and cause some issues with the 6AS7 behind it.

If it will handle a 12AT7, that lowers mu to 60 and increases bandwidth to 40k and should eliminate or greatly reduce the miller capacitance issue and prevent any audible effect.

 

[Thomasr]

What's the output impedance on this amp? The specs say it's suitable for driving headphones between 60-600 ohms, so I assume the output impedance is around 30 ohms or so?

 

[Apos Audio]

What's the output impedance on this amp? The specs say it's suitable for driving headphones between 60-600 ohms, so I assume the output impedance is around 30 ohms or so?

Hi there,

The output impedance is 5.3 ohms.

 

[Narius]

Hi there,

The output impedance is 5.3 ohms.

That seems extremely low for an OTL amp.

 

[jonathan c]

That is. Other OTLs with low output impedances include: Linear Tube Audio MZ2, MZ3, Velo and Schiit Valhalla 2. The more typical OTL has an output impedance of about 100 ohms.

 

[flador]

I'm very impressed that in switching from a PCB to point-to-point wiring going from the TA-26 to the TA-66, the price has gone down. If the sound benefits from the new design and construction, this could be a fantastic deal for an OTL.

 

[flador]

That is. Other OTLs with low output impedances include: Linear Tube Audio MZ2, MZ3, Velo and Schiit Valhalla 2. The more typical OTL has an output impedance of about 100 ohms.

The output impedance on the Schiit Folkvangr OTL is similarly low:

18 ohms (hi gain), 7 ohms (low gain),
8/3.5 ohms with impedance multiplier hi/low gain

Schiit managed to get it down to 7 ohms without using the impedance multiplier, so I think it's reasonable xDuoo was able to get it to 5.3 Ω, but they could be using a similar technique to the multiplier in Folkvangr.

 

[dudeduck]

Does it have pass-through on the aux output so that is passes the signal unaltered when the amp is off?

 

[borkenarrou]

Any impression of the sound so far with HD-600 / 6XX compared to TA-26(S).