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UK: GB150 & GB300 + Toroids and others

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diyAudio Member
Joined 2004
Hi all, selling some stuff:

All prices are +P&P except the amp modules(UK only).

4 x Fully constructed and tested GB150 amplifier modules. TWO REMAINING

These are also known as the SKA (Simple Killer Amp) and were designed and built by the talented Greg Ball.

These are absolutely superb little amplifier modules. Stupidly daft value for money. I've directly compared these to AKSA 55N+, Roksan Kandy Mk3 and a Bryston 9BSST, the SKA was preferred and the Bryston retails for over £3k !

Includes construction details.

I posted a few paragraphs of thoughts on the GB150 sound:

Anyway I decided to start out with some of the really good quality recordings I have and the first was the Andreas Vollenweider' "Vox" album. There's some great acoustic peices here that mix synthesized with natural. The SKA really is a top notch amp to the extent that its actually hard to fault, at least for me anyway, perhaps I haven't heard enough excellent amps? Eitherway I seriously doubt anybody would rate this amp as less than very good and consider the price that Greg is asking... he could ask double and I'd still have payed it.
Another important thing to mention is that the SKA's I have use only base components, so no fancy blackgates or other expensive electrolytics, no silver mica's, no 0.01% resistors etc. so in other words there's actually room for improvement however small it could be. But its interesting to see that design does so well in standard guise, I guess Greg' anal approach to design looks more toward layout and topology than diminishing returns offered from the esoteric components route. But if anyone want to hotrod one of these its entirely possible.

The biggest thing for me about this amp is its sharp but extremely smooth character. A contradiction? Not at all, its got top draw detail but it always seems to presented with a nice natural edge. Greg cites this design as low distortion (~0.008%) but to my ears it isn't like some of the other low distortion designs, its not bright and over hyped but its feels just as detailed with a really appealing softer edge that makes listening very easy. More refined overall I'd say is the best way of putting it and especially in the upper frequencies.

Soundstaging is amongst the best I've heard from a solidstate designs and really only seems to be limited by the recording and the rest of your equipment. I'm feeding it with some great quality DAC's and bit perfect playback so this gives the SKA one of the best signals it can hope for. The SKA doesn't flatter rubbish recordings and they still sound rough but not to the extent that you couldn't enjoy them its just that in comparison to the better/best recording you don't get the awesome realism and that really involving nature.
What it does do with the right recording is completely fool you into thinking that your actually listening to the real thing. It does a great job of creating spaces and sizes, it seems to be able to relate the whole picture with proper proportions without blowing things up or bringing details to the fore that perhaps should be so obvious. Like I said the best word for this is natural, its often used word and there's varying degree's of it but here it really does feel right.

Tonality was perhaps covered in the last bit but just to be sure; its just plain natural Go play the piano (if you have one) or another musical instrument and then go listen to something similar on the SKA. It sounds very nearly as real. Few amps I've heard do this. If only it had an ounce more detail it would be heaven but then again my speakers are most likely the weak link though that's about to sorted out in a big way.

Imaging is drool worthy. I'm sure some folks can relate to what I'm about to write; have you ever heard those systems that have the kind of imaging that suspend disbelief? Well the SKA is nearly as good and again my speakers and room are probably the weak link so I expect improvments in the future. When playback is going on you hear very precise locations of certain sound or voices. You even get a good sense of depth with it being apparent that things are further away than other sounds. Another big deal is the amps great way with folly effect. I listened to many tracks and a few had me thinking that I could hear reflections off walls behind me but what I was actually hearing was the acoustic space of the recording, its a amazing effect to hear and always puts a smile on my face.

Bass again is better than I'm used to with the AKSA. Tight, smooth and rhythmic. I think that bass performance of many amps is one the biggest let downs and that a well conrtolled bass lift the entire performance on a notch. Room problems could be blamed but I do use DRC so that isn't a big problem for me.

Overall I'd have to say that this is the best DIY design I've come across yet and just happens to be the cheapest too. Its very hard to fault and I really do think that any real improvements above and beyond what performance is offered by the SKA isn't to be had from better amp design but from considerations of room and better loudspeakers.

The above was taken from this thread: http://www.diyaudio.com/forums/showthread.php?postid=842783#post842783

There's also comments on the sound from other users in that thread and also here:

http://www.audiocircle.com/circles/viewtopic.php?t=25308

Gregs website is here but please don't judge his web authoring skills against his amplifier design :rofl:

Details and Specs: http://members.dodo.com.au/~gregball/guru_003.htm

Superb value at £40 each

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2 x Fully constructed and tested GB300 amplifier modules

Same as above but twice the power at 300w into 8ohm. Same superb sound but with better handling of tough loads, high SPL and more dynamic. IMO the GB300 is very slightly better than the already excellent GB150.

Includes construction details.

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

Superb value at £60 each

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45-0-45 800VA Toroid

Would suit the GB300's above perfectly.

Dual 45v secondaries and dual 120/110v primaries, perfectly OK for UK mains since I've been using it that way, just wire the primaries in parallel. Includes a couple of neoprene vibration cushions and all mounting accessories. Absolutely no hum from this. Bought from farnell for £48 a couple of months ago. As new condition with perfect leads (not chopped or mangled) and never mounted in a case.

£25 please

Forgot the photo for this one but I think everyone knows what one of these are by now :)

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Tons of random bits SOLD

I really can't be bothered to catalog all this so I'll just list roughly what included, think of it as lucky dip :D

  • A thousand or so resistors, varies values and virtually all 0.5/0.25w 1% types and around 12 large 7w types + 10w ceramics.
  • A few Blackgates 50v standard type capacitors
  • Semiconductors (LN5819, BC559, BC549C, N5819, MPSA42 etc. etc.)
  • Around 10x BB OPA2134 Opamps
  • Fuses + PCB fuse mounts
  • PCB pins
  • 4 x 35A 600v high quality metal cased bridge rectifiers
  • A couple of Multi-turn pots
  • A fair few caps from the likes of Vishay, Elna, Nichicon. Mostly polystyrene types and electrolytic
  • XLR connector, 4 x gold plated and chunky binding posts, 1/4" TRS connector.
  • TO220 Mica washers and mounting hardware
  • Other stuff

Please, please don't ask me to identify the items, I've priced them to take into the account of the uncertainty of the contents.

BTW: The components are virtually all clearly marked, so you can identify them quickly.

£30 to help me clear this stuff out please

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diyAudio Member
Joined 2004
Walling Jig mk2 parts.

Here's a box for the Wallin Jig Mk2 needed for speakerworkshop measurements. All you need to complete is a few resistors and to fit the parts. Includes all switches a couple of binding post and gold plated RCA sockets. There's also a few extra binding posts along with a few more chassis mount gold plated RCA sockets.

Here's the design: http://www.vikash.info/audio/sw_jig/

  • 6x Chassis mount RCA sockets (red and black)
  • 4 pairs of binding post
  • ABS mounting case
  • All switches required for the Jig

£12 for the lot

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ESP P71 Linkwitz Transform boards

2 are built up and test as working. Tuned for Seas L22RNX4P in a sealed 25ltr cabinet. With the transform in place the response extends down to a flat 20hz in room. Maybe suitable for other drivers or alternative you can remove components and repopulate them :)

The constructed ones feature BB OPA2134 Opamps.

There's also a single blank P71 PCB.

£13 for these

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Microphone Preamp PCB + 2 panasonic WMA61a mic capsules SOLD

Vikash very kindly gave these to me and rather than never use them I thought I'd return the favour to someone else. Details can be found on Vikash's website.

Free!

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diyAudio Member
Joined 2004
pinkmouse said:
Selling the SKAs? What on earth is your new plan? :)

I'll take one of the preamp PCBs with the capsule, and I'll check the bank account tomorrow to see if I have enough cash for the components.

Hi Al,

I've just bought a B-Grade Chord 1200E standard from Movement Audio. (some minor scratches to the top and two very small identations.)

http://www.chordelectronics.co.uk/products_detail.asp?id=14

I'm on the look out for another 2 either the 1200c or 1200e. But they aren't cheap. Fantastic build and the sound is just so 'spot' on. Heard one of these at the Northern Hifi Show at the Manchester Radisson Hotel this year and was absolutely gobsmacked, as soon as saw the the b-grade model for silly money I just ordered it without even thinking.

Hasn't arrived yet but I know what to expect so the GB are going, still very strong amps though just not Chord territory.

The preamp and electrets are yours, let me know about the others.
 
diyAudio Member
Joined 2004
I've also got 2x 4U rack mount cases that someone can have FOC if they collect. They're in as new shape but I sprayed the front panel gloss black and its started to flake off - obviously I didn't do a very good job :) The Fronts want rubbing down and redoing with some metal primer this time, would be perfect if this was done.

I'll post some pics tommorow evening but these would be good for a DIY amp project. Cost me Around £40 each from Maplins if I remember.
 
diyAudio Member
Joined 2004
The Saint said:
How about 20 Pounds each for the GB150s

How about, forget it. :)

I'd rather let them gather dust, just in case I did need them in future. Sorry but £20 is an insult for amps of this calibre, go back read my comments and then offer the asking price if your truely interested.

Sheesh, the cheek of some folks. And from AH of all people who should know the value of a good amp.

Offers considered but not 50% off an already stupidly cheap price for the performance on offer. Like I said before, these compared very favourably with a £3k Bryston and the AKSA 55N+. Enough said really.
 
diyAudio Member
Joined 2004
The Saint said:
no insult intended :)

When you offer secondhand amp modules for sale
of cause I am going to try to get them cheaper.
regardless of their quality
40 pounds works out to be about $100.00 AUS
I can buy the kit for that
:D

So please no offence, its just business...

No problems.

As you've probably gathered, I think pretty highly of the modules, more so than any DIY design and commercial design I've had before so I'd rather keep them for a rainy day than sell them for peanuts. Afterall £20 only buys you a couple of CD's here in the UK let alone an amp that sounds like it should have a £2k price tag.

The price is really aimed at folks in the UK since £40 includes P&P and the modules are built, tested and guaranteed working. If your comparing like for like you really should be quoting Gregs pre-built option which works out at around $155AUS per module. But since you build amps for a living its not such a big deal to build the kit up for others it maybe. I guess the postage to Australia is less than economical too.

Like I said before, I'm open to sensible offers.
 
diyAudio Member
Joined 2004
I almost forgot:

I have an assortment of Blackgate standard and N types that will fit the GB150 and GB300 in all the critical positions that Greg has cited to offer the most improvement. There's also Audionote Tantalum resistors to compliment the Blackgates.

These are offered to anyone buying the modules or simply to anyone interested in upgrading their own GB amps.

Let me know if you need more details and a price.
 
diyAudio Member
Joined 2004
Also for sale:

2x 35v 300VA toroids

The toroids are dual 35v secondaries with 300VA rating and single 240v primary winding. These are top notch audio grade toroids: Its an encapsulated design featured a shielding layer then an ABS outershell and finally a resin pour to hold the whole thing together. The hum is absolutely zero and the EMI is reduced even further over a conventional toroid. Unfortunately this means they are somewhat larger and heavier than you would otherwise expect.

Perfect for the GB150's and I believe these would also be suitable for the AKSA 100 series.

£20 each since they're as new with the leadouts in perfect condition.


45v 800VA Toroid

Would suit the GB300's above perfectly.

Dual 45v secondaries and dual 120/110v primaries, perfectly OK for UK mains since I've been using it that way, just wire the primaries in parallel. Includes a couple of neoprene vibration cushions and all mounting accessories. Absolutely no hum from this. Bought from farnell for £48 a couple of months ago. As new condition with perfect leads (not chopped or mangled) and never mounted in a case.

£20 please

An externally hosted image should be here but it was not working when we last tested it.
 
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