Simple Killer Amp - Introductory Offer!

amplifierguru · « **on:** 1 Feb 2006, 01:27 am »

Hi all,

This simple, discrete, power efficient fully complementary 'Patent Pending' 150W Class AB MOSFET amplifier module kit is receiving accolades for it's stunning naturalness, accuracy and tireless sonics. It is available for only a few more days at the ridiculous trial introductory US$100 per pair, and the larger 300W version US$160 per pair until mid Feb, when a 50% price rise is planned to establish viable/sustainable commercial operation.

This has been introduced on other DIY forums and I thought it only fair to make the same offer for audio circle readers. Please check my (personal) website which will, no doubt, need to be upgraded to something more commercial, in coming weeks.

Cheers,
Greg

Occam · « **Reply #1 on:** 1 Feb 2006, 04:27 am »

Greg,

Its a very fascinating and elegant topology.... But where is the Vas?

I assume the patentable part is the bootstrapped differential stage? I've never seen the like. Your gain is in the input and output stages with just the EFs betwixt and between. Very cool

...... original and 'green'.

Regards,
Paul

amplifierguru · « **Reply #2 on:** 1 Feb 2006, 05:01 am »

thanks Occam,

The amp has some 80 dB gain from the input diff'l stage due to positive feedback (bootstrap C's) and high linearity due to the greatly reduced Ic modulation. Then it is buffered by the complementary 30mW 300MHz (!!)EF driver stage driving the lateral MOSFETs (Vgs = 3.5V) for a further 30 dB gain. The signal at the gates is typically 2Vrms for full output. The only compensation is feedback lead comp (small C) and some tailoring of the zobel. The MOSFETs drive to 2V of the rails so require a smaller power supply resource for given power. And it sounds stunning with only 50mA per MOSFET of standing current. So 10W or so standing dissipation.

Green, green it's green they say....

The bridge discrete diodes have a non repetitive surge current rating of 200A. The C's are not special low ESR types relying on the paralleling and close proximity for low Z.

Cheers,
Greg

JoshK · « **Reply #3 on:** 1 Feb 2006, 04:59 pm »

I am not as technically adept as Occam, but I saw on your site that you can build your modules for Class A or A/B. Do you use global feedback and if so is it customizeable at all?

ctviggen · « **Reply #4 on:** 1 Feb 2006, 05:10 pm »

What website?

JoshK · « **Reply #5 on:** 1 Feb 2006, 05:13 pm »

click his "www" button...

Marbles · « **Reply #6 on:** 1 Feb 2006, 05:14 pm »

http://members.dodo.com.au/~gregball/guru_002.htm

ctviggen · « **Reply #7 on:** 1 Feb 2006, 05:15 pm »

When did the www buttons appear? Or have I been missing these for a while? Thanks for the info.

Marbles · « **Reply #8 on:** 1 Feb 2006, 05:21 pm »

It's hell gettin' old Bob

ctviggen · « **Reply #9 on:** 1 Feb 2006, 05:38 pm »

It is hell! (Though my short-term memory has never been good.)

R_burke · « **Reply #10 on:** 1 Feb 2006, 07:14 pm »

Quote from: ctviggen

It is hell! (Though my short-term memory has never been good.)

Whis is directly related to too much partying

amplifierguru · « **Reply #11 on:** 1 Feb 2006, 09:40 pm »

Well Hi Guys,

Sorry Bob I should've linked to the module for you.

http://members.dodo.com.au/~gregball/guru_004.htm

hi JoshK,

Yes the amplifier can be configured for Class A up to 50W/8 ohm or Class AB 4/8 to 150W. Early indications from owners who have tried both indicate there is no tangible advantage in the Class A configuration and that the amp sounds magic in low bias AB - which was certainly part of my (green) agenda. I might add that, for those who must have Class A with the massive heatsinks and continuous duty power supplies, that this amp will go to within 2V of the supply rails producing 50WA from little more than +/- 30V allowing 35V C's at a pinch.

Cheers,
greg

Russell Dawkins · « **Reply #12 on:** 1 Feb 2006, 09:56 pm »

Greg,
I don't see a power supply listed for the GB300D. Am I missing something obvious, apart from a few brain cells?

amplifierguru · « **Reply #13 on:** 1 Feb 2006, 10:41 pm »

Hi russel,

Yes you're correct ( can't say about the brain cells though). I have not produced a modular PS board for the GB300D. The amplifier requires a simple full wave rectified split supply of typically +/-50V (4 ohm) to 70V (8 ohm) for normal operation. The output stage has 8x 150W MOSFETs and with proper heatsinking (typ 0.4C/W) can accomodate wide phase angle loads with reliability. Capacitance need only be enough to keep maximum ripple under signal input levels, due to the high PSRR of the topology i.e. +/-15,000uF to 20,000uF, higher for 4 ohm lower for 8.

Cheers,
greg

ctviggen · « **Reply #14 on:** 2 Feb 2006, 12:33 am »

So, the voltage rails decrease with increasing ohms? I thought it would be the other way around for current reasons.

amplifierguru · « **Reply #15 on:** 2 Feb 2006, 12:48 am »

Hi Bob,

For 150W into 8 ohm Vp=49v so supplies can be +/-55v while for 150W into 4 ohm Vp=35v so supplies of +/-45v will suffice.

The output stage is 4 x 150W MOSFETs for 600W capability so the amps can drive any phase angle at these ratings with good heatsinks.

Cheers,
greg

NealH · « **Reply #16 on:** 2 Feb 2006, 11:36 am »

What is the level of feedback used in this amp - 20db, 30 db?

skrivis · « **Reply #17 on:** 2 Feb 2006, 02:15 pm »

Quote from: amplifierguru

Hi all,

This simple, discrete, power efficient fully complementary 'Patent Pending' 150W Class AB MOSFET amplifier module kit is receiving accolades for it's stunning naturalness, accuracy and tireless sonics. It is available for only a few more days at the ridiculous trial introductory US$100 per pair, and the larger 300W version US$160 per pair until mid Feb, when a 50% price rise is planned to establish viable/sustainable commercial operation.

This has been introduced on other DIY forums and I thou ...

Very nice.

Best of luck to you and I really hope you do well with the new venture.

JoshK · « **Reply #18 on:** 2 Feb 2006, 02:42 pm »

Do you use global feedback and if so is it customizeable at all?

mgalusha · « **Reply #19 on:** 2 Feb 2006, 03:09 pm »

I'm going to have a go at a pair. My collection of too much stuff includes an old pair of Parasound HCA-1201 amps. I believe there is enough heatsink in those for the 150W A/AB modules and I've enough spare parts for the power supply so the cost is going to be minimal. It will be interesting to see how they compare to my LNPA's and the Odysseys.

Greg, you have email.

Mike