AKSA Phono Pre

Oz_Audio · « **on:** 28 Apr 2003, 02:09 pm »

I finally got around to building a Jarrah box for the phono pre so it matches my GK1 and 55 Power amp.

When I did, I also wanted to look at the thing.

Originally I had very short Interconnects, hot wired from the phono pre to the GK1, but being very short, I had to put it out of sight.

So, I got out the soldering iron and made up some more Beldon Cat5 cable and made a 1m long IC with a 1m long power cord from the GK1.

Now it sits proudly at the bottom of the shelf next to the Linn Turntable. Looks very good sitting there.

Anyway, have much longer interconnects I was expecting a change to the worst, but to my surprise, the sound coming from my speakers is clearer and with more head room, a more life like with easier delivery sound.

I can only put this down to the IC from the TT and the Phono pre are now away from the other equipment.

This has prompted me to build a better table for the TT, I presently use an old "Dekstand" an Australian TT table from the 80's.

I will go for a similar design to the one used by Chris Brady from Teres Audio http://teresaudio.com/haven/
I will build it with a small table under the main platform to put the Phono pre on, this will get it even further away from all other equipment.

One can never stop fiddling with Audio gear

JoshK · « **Reply #1 on:** 28 Apr 2003, 04:15 pm »

thanks for pointing this out! This looks like a fantastic idea for a TT stand! Gives me lots of ideas!

PSP · « **Reply #2 on:** 28 Apr 2003, 04:35 pm »

Apologies if this is a dumb question... I know that Hugh sells a phono stage as an upgrade to the GK-1b/c. I may have missed something... but is this phono stage part of the GK-1, or a seperate product?

Thanks,
Peter

Oz_Audio · « **Reply #3 on:** 28 Apr 2003, 10:09 pm »

PSP,
Its part of the PCB of Option 2 and Option 3. It will be mounted within the GK1.

I have been a Beta tester for Hugh so all I got was the Phono section of the PCB for testing.

Hugh may market the Phono pre as a stand alone unit if there is enough interest in it.

Mark

AKSA · « **Reply #4 on:** 28 Apr 2003, 11:10 pm »

Peter,

The phono option, moving magnet, is mounted on the input/switching pcb of both the manual and the remote versions of the GK-1.

It's there, waiting for the components, on every purchase of the GK-1M and GK-1R. The option is an additional $AUD210 (around $US129.80) with either of these versions. It's not available on the Entry Level, of course.

On the GK-1R: Today I sign off on the final pcb for the remote, the keypad. This has taken about 50 hours to design; quite surprisingly complex. It uses IDC connectors from PCs, 2x5 pins. A ribbon cable comes off the digital control board, passes to the relay/switching board, then daisy chains to the keypad (which has indicator LEDs on it). All this has tested very well, and the remote is very mod, in silver and black! As promised, the RC5 Philips codes will be incorporated with the product so you can program a universal remote, with all codes specially chosen as so wacky no existing consumer device will clash. We don't want TV channel selection to switch in phono, after all!

It's interesting how all this pans out. Let's assume 350 hours of design between the two of us. 80 is spent in design, 120 in pcb design, 15 in sourcing, 50 in prototyping and testing and 85 in documenation. These are ball park; I'm sure Dale Herman of APOX fame will bear this out!

But the satisfaction of covering twenty or thirty permutations of every circuit and layout block and settling on the best is palpable; you know that you have completed a very tough job - home DIY is very different to commercial design because there are so many production and cost factors to consider. I'm confident this is a very, very good implementation which will be straightforward and logical to make and very durable.

Cheers,

Hugh

Malcolm Fear · « **Reply #5 on:** 28 Apr 2003, 11:39 pm »

To Oz_Audio

I have been using a Dekstand for my Linn, since the 80's.
For those who don't know the product, it is a light weight frame made from aluminium square section tubing, with a light weight rigid "aero" sandwich platform that sits on top. The idea (from memory), is that a light weight rigid stand would vibrate at a highish frequency. The Linn, with its springy suspension, would absorb any frequency above its own resonance (around 18 hz).
There was an old saying that the Linn sounded better sitting on top of the cardboard box that it came in, than any heavy rigid support system.

I would be very interested in your findings on the stand you are going to make. I bought the Dekstand, shoved my Linn on top, and have never thought further about it.

regards

Oz_Audio · « **Reply #6 on:** 29 Apr 2003, 04:17 am »

I think all Linns sold in Australia the 80's had a Dekstand under them, but after 20 years, 10 house moves through 3 countries and back to Oz, its looking a bit worse for wear!

As for the new stand, it will be built it very similar to the one at Teres Audio, but I will be experimenting with suspension at the top.

Apart from sand I will be using whole squash balls, table tennis balls and tennis balls, both whole and cut in half.

This will give a good solid stand that cannot be bumped with the qualities of the Dekstand. I will be using the Dekstand top for all varients as it is very rigid and light.

Hopefully in about 2 weeks I'll have it finished.

Mark

Malcolm Fear · « **Reply #7 on:** 29 Apr 2003, 09:18 pm »

Hi Mark
I have been down the "squash ball, raquet ball" route. The best I have found is the half inflated 16 inch bike innertube. Go to Big W or such for them.

Oz_Audio · « **Reply #8 on:** 29 Apr 2003, 10:57 pm »

Malcolm, so if you have tried the "ball" route and as I understand it you are still using the Dekstand, I may modify my design and build a solid stand for the Dekstand so the TT is at the same hight as the Pre.

Do you prefer the sound from the Dekstand?

Mark

Malcolm Fear · « **Reply #9 on:** 29 Apr 2003, 11:15 pm »

I tried cut squash balls under the Dekstand. Couldn't hear a difference.
Tried innertube and Corian shelf. It was difficult to get it level. So went back to the Dekstand as is.
I thought that perhaps another approach is to use 2 or 3 smaller innertubes (scooter perhaps). Then you could vary the inflation in each to get the turntable level.

andyr · « **Reply #10 on:** 30 Apr 2003, 08:30 am »

Hi guys,

Dekstands were a brilliant invention for the time and used to be de rigeur for LP12s in Oz - I also bought one with mine and for many years never thought about it.

However, I have had for many years an Ortofon, battery-powered ultrasonic stylus cleaner. You put this on the platter, the small semicircular indent at one end against the spindle and put the stylus on the vibrating pad at the other end.

It makes a high-pitched buzzing sound when operating (and you have to turn your volume control down to zero) ... and I noticed the pitch warbled when I tapped the benchtop the Dekstand was sitting on - IE. I was getting accoustic feedback from benchtop, through the Dekstand to the platter.

This accoustic transmission I thought must be bad ... the t/table needed isolating!

So I made up an isolation platform - similar to the one described on www.enjoythemusic.com. A 15kg piece of slate (about 25mm thick) resting on 4x9 squash balls. Each support 'leg' of 9 squash balls has a low wooden 'fence' around the balls, to stop them moving around.

The difference was amazing - I got a whole lot more base ... and, hitting the benchtop with a hammer whilst using the stylus cleaner no longer caused the buzzing tone to warble.

Because I had achieved accoustic isolation, I actually stopped using my Dekstand but I probably sometime should just see if I can hear a difference, with and without.

Anyway, for my next house, I was thinking about a sand filled isolating 'pillar stand' for my LP12 but then a mate showed me what he had done with his LP12, which he swears by.

He made up a wall-mounted shelf - two right angled lengths of Al (say, 70mm x 70mm x 450mm ... from your friendly Capral store) welded to a 12mm Al backplate. You Dynabolt this to your wall and the two arms stick out far enough to support the t/table plinth. You put spikes into the t/table supports, pointing upwards, so they take the weight of the plinth.

This couples the plinth to the 'shelf' which itself is bolted to the - preferably brick - wall. This provides a accoustic 'sink' to drain all vibration away from the plinth. Yes, if you have an energetic next-door neighbour whose bedhead keeps banging on that wall or your house is sited above a subway, you are going to get trouble but in normal domestic situations, you won't be getting vibrations coming from the walls of your house.

Regards,

Andy