[Todd]

HI All,
 
Today we are very pleased announcing the replacement amp for the Peak and Volcano, the Apex HiFi Sangaku. The Sangaku will sell for $2000. The Sangaku is a hybrid amp utilizing a tube input gain stage and solid state output stage with a 1 ohm output impedance. It has a 1/4" and 4 pin XLR outputs for single ended or balanced use.
 
The Sangaku is also a very good preamp for desktop or main rig use.
 
 

 

 
 
 

Here are a few key points:
 
·       3 inputs, one balanced & 2 unbalanced (selected by front panel button)
·       Unbalanced and balanced (4-pin XLR) headphone outputs and unbalanced preamp out (selected by front panel button)
·       Hybrid design using a mix of directly heated triode and semiconductor stages
·       Integrated linear AC power supply
·       Two gain settings
·       Up to 11V RMS out – and 1 watt into 32 ohms – can drive pretty much anything
·       Small size – 8.5” x 8.8” x 2”
 
       We are now taking preorders and expecting to ship in 4-6 weeks. You can order online here or call us at 406-285-3910
 
      Todd

 

[MisterMoJo]

That looks like a very interesting amp.  I especially like the use of the Nutube.  When those burn out however, are they user replaceable?

 

[Wildcatsare1]

Todd,

Looks like a fantastic amp, I look forward to learning more about this Amp!

 

[smial1966]

The Korg website states a Nutube life expectancy of 30,000 hours. So using it 4 hours a day, every day, it should last for 20 years. 
 
Quote:

  That looks like a very interesting amp.  I especially like the use of the Nutube.  When those burn out however, are they user replaceable?

 

[raybone0566]

Todd,
Any chance of a loaner tour on this.

 

[MisterMoJo]

 

OK, that is really great but what if one goes bad?  Is it user replaceable?

 

[glassmonkey]

Sounds like a great amp. I do wish it threw out more than 1 watt, though, as I've found my HD600 to like more power than that. You adding this to your cave of wonders @smial1966?

 

[smial1966]

If Todd is amenable to my proposition then the Apex Sangaku may well appear at the UK Head-Fi Meet next April.

Sounds like a great amp. I do wish it threw out more than 1 watt, though, as I've found my HD600 to like more power than that. You adding this to your cave of wonders @smial1966
?

 

[glassmonkey]

If Todd is amenable to my proposition then the Apex Sangaku may well appear at the UK Head-Fi Meet next April.

 

 
It has switching power, too.

 

[Todd]

HI All,
 
to answer a question or two...
 
The tube is not user changeable. We will be around to do it but we think the tube will last a very long time - 10 to 20 years.It is soldered directly into the Sangaku circuit board.
The Sangaku will be ready to ship by the end of September.
 
Todd

 

[pmillett]

I posted a little more info about the Sangaku on the Apex HiFi website at http://www.apexhifi.com/Sangaku.htm.
 
It's a pretty cool little amp.  It has the sonic characteristics of a directly-heated triode - which in fact the NuTube is - and the drive capability of a low-impedance solid-state amp.  I've been listening to it with K1000's, and it sounds great to me!
 
Here is what a NuTube looks like:
 

 
Pete

 

[deafdoorknob]

great to have you back Pete!!

 

[jelt2359]

I spoke to Pete via PM's and got a wealth of information about this amp, and Todd gave me the go-ahead to share for anyone else who was interested.
 
First of all, this is a very different amp from the Peak/Volcano. It really should be considered a successor in terms of price point only. It has more "single-ended triode" sound (mostly second harmonic distortion), for a more tubey presentation than his previous hybrids. This is a result of the way the Nutube's circuit was designed, and imho is probably the key reason to get this amp- it's the first one using the Nutube! Nonetheless, bear in mind that most of his tube amps do tend to have broadly similar sonics- in short, there is a "house sound", a certain harmonic mix that he shoots for. He typically does this by moving the operating point of the first tube stage. Some other differences between the Sangaku and the previous Apex hybrids: The new amp has much more output voltage driving capability than any of the previous hybrids; and also the lowest output impedance. Part of this is because of the Nutube- it only uses milliwatts of voltage. At the same time, the power supply voltage on the Sangaku is much higher (+/-18V, vs. 12V or 10V) to provide bigger output swing. 
 
The output stage is also different from the Peak/Volcano. The Peak/Volcano had a discrete MOSFET buffer. In the Sangaku, however, Pete has moved back to using power opamps. According to him the Peak was more of an experiment to see how well he could do without an opamp, but he's since decided that power opamps are better. He knows that some will argue that this is a less 'pure' approach, but he's made his choice- they dissipate less power, are smaller, and simply just perform better. He's implemented these power opamps with CCS loads on them to keep them in class-A operation at low signals. Nonetheless, when driving lots of current, the output still goes into class AB operation. The CCS keeps more bias current flowing, which reduces any crossover distortion, an issue most problematic with small signals. This is what Tyll had said about this approach in the past:
 
"Class AB op-amps are configured such that the positive side of the amplifier amplifies the positive half of the signal, and the negative side of the amp the negative half of the signal. There is an area around zero where both halves, or neither half, is doing the amplification depending on how the amp is biased.
 
Using a constant current source/sink to draw current continuously out of an op-amp forces this "cross-over" region to become wider such that both sides of the amp are running for more of the time, or operating in class-A.
 
The current sink attaches directly to the output of the op-amp.

Read more at http://www.innerfidelity.com/content/butte-headphone-amplifier-apex-hi-fi"
 
Finally, the Sangaku is not DC coupled, but it's -3dB point is very low (single-digit Hz).
 
After all the info Pete gave me, including how he's made certain choices after learning from his experience designing the Peak; the sonics of the Sangaku ('300B-like' was thrown out at some point to describe it) in such a small package (and with no tubes sticking out from the top!), I'm happy to say this will be joining my Apex Teton soon. With its low output impedance, I forsee it as a great match for my planars (this low output impedance one of the key design goals Pete had for this amp, exactly to match with these increasingly low-impedance headphones).

 

[lukeap69]

Many thanks for this info and will be looking forward to your impressions when you received your unit.

 

[jelt2359]

Me too!