[xrk971]

Another NHB amp tuned for LCD-2 just shipped to a member in Singapore.

Sounds great and measures superbly well:

 

[xrk971]

Silicon Harmony is getting closer to being a real amp. It's in a nice Class A case now - heatsinks are a cool 50 deg C. Running of a 19.5v SMPS brick which is then stepped up to 30v. Wonderful sounding amp. The most powerful bass I have felt.

Capable of about 6w of pure SE Class A power into 8ohms.

 

[xrk971]

I connected Silicon Harmony to my Focsurite DAC (capable of 192kHz at 32bit), and played a high res 176k FLAC file of Spyro Gyra's Dreams of Toledo. Wow. The better the source, the better it sounds. Here is the FFT profile of this amp into 33ohms. Predominantly H2 distortion at -66dB and H3 at -90dB. Not much else. There is a bit of odd noise sneaking in from one of the DC step ups which may be going bad as I can hear a slight whining noise from it. Will change those out shortly for some new ones with a proper heatsink.

FFT for 33ohm load:

I love the dynamic range of this amp. From the blackest blackest blacks (no noise when no music playing even at full volume - cannot tell it is turned on), the how hard it hits you when the headphone frame recoils on a kick drum.

 

[gikigill]

EWhat's the output at 50ohms?

 

[xrk971]

You mean power at 50ohms? I am listening with 55ohm headphones but they are 96dB and it can get painfully loud if not careful with volume knob. Let me rig up a 51ohm power resistor and measure the max output.

Edit: Ok, just measured the max power into 51 ohm 2w power resistor. With O-scope attached to show unclipped, max is 17.1\7v peak-peak or 6.28vac as shown on Fluke. That's about 800mW into 51 ohms or 5w into 8ohms - per design spec. Clipping limit could be increased but requires running amp at higher voltage and case heatsink should not be pressed for more than circa 32w/channel as this current configuration at 29v Vcc is giving 55 deg C heatsink temps. The bias current is currently at 1.1amps and can be adjusted as high as 1.5amps to increase power, but at the expense of higher heat output.

If you think 800mW into 51ohms is not much, well it's pure SE Class A power derived from burning 32w in the heatsinks. 2.5% thermal efficiency is very Class A manly-man power

 

[gikigill]

Sounds tempting!

 

[xrk971]

I have had it on and running three days straight to burn in and make sure all is well from reliability stand point. I am adding local heatsinks to the power supplies to further enhance their reliability. The PSU auto detects for 110/220 vac so good for using anywhere.

 

[xrk971]

Sounds tempting!

Yes, the Silicon Harmony is the Class A temptress from the Audio Underworld!

 

[Lucas_ob]

your AMP REALLY cute

 

[xrk971]

your AMP REALLY cute

Which one, the little one or the big one?

 

[xrk971]

Silicon harmony with internal SMPS and neater wiring.

 

[xrk971]

Sounds wonderful with good full range speakers too. Playing in the speakerlab: on the left is an XKi (Xrk's Karlson ab-Initio 6th order bandpass) with Tang Band W5-2143 and on right is tapered TL with Fostex FF105WK. Both are circa 89dB sensitive drivers with cabinets that give them bass extension down to about 55Hz,

Also note that you can plug in headphones in addition to listening to your 8ohm speakers simultaneosuly. It can handle it.

 

[xrk971]

Silicon Harmony finally makes it out of the lab and into the house. Here it is paired with a Focusrite 2i4 2gen as a DAC. Currently listening to high res FLACs with Status OB-1's. Superb sounding combo.

 

[xrk971]

Single Ended (SE) pure Class A topology single to balanced converters that now enable two Pocket Class A amps to power balanced drive headphones. Converters use premium Wima film and Elna Silmic II caps. Capable of driving 10v peak to peak from 48v single rail. Super low distortion for a very transparent insertion in audio chain, yet retains sonic character of the Pocket Class A amp.

 

[DBaldock9]

Single Ended (SE) pure Class A topology single to balanced converters that now enable two Pocket Class A amps to power balanced drive headphones. Converters use premium Wima film and Elna Silmic II caps. Capable of driving 10v peak to peak from 48v single rail. Super low distortion for a very transparent insertion in audio chain, yet retains sonic character of the Pocket Class A amp.

I'm very interested in this particular project!