[whubbard]

Mark,

That's quite an impressive list you've got there! Your probably going to need quite a funky case setup to accommodate all those caps! I personally have TKD attenuator bypassed with Vishays, but I think the DACT will do just fine.

I can send some matched BC560s your way via the USPS if you would like. I've got a bunch left over from the group buy and the envelope is light enough that the cost of shipping to Australia is negligible. Shoot me a PM.

-West

[andyr]

My GK1 has finaly died and I am going for a total rebuild.

I don't know if I can afford this wish list, but here is what I gather are the best possible upgrades:

C1             Sonicap Platinum 1uF
C4 & C7             Audiocap PPMF 40uf
C6             Oscon 47uF 20V ?
C11 + C12          Nichicon Gold Tune 100uF 63V ?
C10 + C14          Nichicon KZ 100uF 50V ?
C19             Sonicap Platinum .01uF
C21             Original 1uF Auricap bypassed with Sonicap Platinum .01uF
T1, T2, T4          BC560 (matched)
R5, R9, R11, R22, R26a, R26b.    Riken Ohms, Vishay etc

Mark

"Missed it by that much!"   

For C10, C11, C12 and C14, IMO use Black Gates - not Nichicon Gold Tunes.

For C6, I used a BG 25v 'PK' in place of an Oscon.

And for C21, use another Sonicap Platinum (or a Mundorf SiO) rather than the Auricap bypassed with a Sonicap Platinum .01uF.

And I would be careful about willy nilly substituting Riken Ohms.  There was lots of discussion about these in early AKSA days (pre LF - so, mebbe 5 or 6 years ago?) and the general consensus was that these reses change their resistance minutely with the amount current going through them.  This means they cause slight "tubey-like" distortion.  So they may make your GK-1 slightly less "crisp"?

That being said, I personally did install Riken Ohms for the reses to the volume control. 

Good luck.   

Andy

[andyr]

Mark,

I personally have TKD attenuator bypassed with Vishays, but I think the DACT will do just fine.

-West

Given the history of how us GK1-cost-no-object types ended up with the TKD/Vishay option (ie. via the late and great Bob Crump and his search for the ultimate volume control), I sincerely doubt that the DACT comes within a bull's roar    ... but given Mark thought he might have trouble coming up with the readies for the upgrade list he quoted, adding another USD370 (at least) for a TKD is unlikely! 

Regards,

Andy

[whubbard]

...and when you don't know what your doing...the naked Vishays fall apart   

-West

[Oz_Audio]

Many years ago Hugh kindly let me be one of the prototype builders and the GK1 was my first soldering job of any kind.  I have no idea how it lasted this long to start with.

I am sure he just wanted to know if a klutz could build it!!!!  All Hugh provided was the parts list, board, valves and valve holders.  I found all other parts from various vendors in Oz.  It worked as advertised.

Anyway I digress.  Far too much ReD wINe.

Since it died about 3 months ago, my wife has even allowed me to fix it, as my very old Musical Fidelity Synthesis is just not up to the job.

Just after I built the GK1 I aslo built Hugh's phono stage and some how used 1W 5% carbon resistors.  I think the originals where not working or something and Hugh suggested a different value and all I could get where these cheepies form Jaycar.

Anyway, I was floored by the transparity and lack of noise from the el-cheepos so I will be using the same in the new GK1.

Now for the details:

Case, no problem, I build from wood and the case will be what it ends up.  I am also finally going to put the N+ upgrade into the 55 so I just might make a floor standing amp case totally of local hardwood so it becomes a piece of furniture.

Mods to a 55 N+ are also accepted 

Cost is as always a problem, but I will try and do the most cost effective and anyway, tax return time is 2 months away so..........or lotto....... or kill the w&%e....... or kill the k%^s...... or mother*&!aw aa

Mark

[RonR]

Mark,

For the 55N+, go for Hugh's new power supply design as used on the latest Amps. The difference isn't subtle!

For the GK-1, I'd use Nichicon KZs at C10, C11, C12 and C14, to my ears they sound more "Effortless" than BGs.

Cheers,

Ron.

[TimS]

Mark,

For the 55N+, go for Hugh's new power supply design as used on the latest Amps. The difference isn't subtle!

Hi Ron

Is there an upgrade available for the 55N+ power supply or are you talking about buying the Lifeforce amp?

Tim

[Seano]

Case, no problem, I build from wood and the case will be what it ends up.  I am also finally going to put the N+ upgrade into the 55 so I just might make a floor standing amp case totally of local hardwood so it becomes a piece of furniture.

Mark....this is fast becoming my re-casing option.  A floorstanding arrangement with the amp, pre-amp & DAC built in to the casework, shelf space for the CD and the top being available for the vinyl thingy.  I am also thunking/dreaming about a panel PC & storage to manage a software library for outout to the DAC.....

....and I'm thinking about a really original name for it like.....phonogram....except I have this vague idea it has been used before 

[stvnharr]

Gidday from Cairns.

My GK1 has finaly died and I am going for a total rebuild.

I don't know if I can afford this wish list, but here is what I gather are the best possible upgrades:

C1             Sonicap Platinum 1uF
C4 & C7             Audiocap PPMF 40uf
C6             Oscon 47uF 20V ?
C11 + C12          Nichicon Gold Tune 100uF 63V ?
C10 + C14          Nichicon KZ 100uF 50V ?
C19             Sonicap Platinum .01uF
C21             Original 1uF Auricap bypassed with Sonicap Platinum .01uF
T1, T2, T4          BC560 (matched)
R5, R9, R11, R22, R26a, R26b.    Riken Ohms, Vishay etc

I will be using my current DACT attenuator and DACT selector with Seimans 7308 Gold Pins.

Have I missed anything?

Mark

Mark,
Well, first of all you gotta fix what broke first, and I'm sure you're covered there.
I don't have too many stock parts in my GK-1. The list must be somewhere here on the thread.
BUT, when it was all said and done, I tend to think that the only things that made real differences have been the Platinum cap at C1 and the 7308 tubes. You've already got the tubes. A good and cheaper alternative for C1 is .47uf Mundorf Silver/Oil.
You can change all the other stuff, just because you can. Afterall, ALL parts are user serviceable.
Have you thought about having the wire from the output pin TO the rca be the same as what you use for the interconnect cable FROM the rca to the amp? It's the same signal, and I like to make these as similar as possible.

Steve

[Oz_Audio]

Hi Steve, yes, I already do the cable that way - all done with Teflon Cat5 strands.

Mark

[RonR]

Tim,

I think Hugh will provide you with the PSU upgrade separately if you talk to him nicely .

Cheers,

Ron

[AKSA]

Thanks Ron,

How are things?  I hope you and the family are well....  I will send you an email!

Hi Tim,

The upgrade to the power supply on the 55 is restricted to Nichicon Gold caps.  The upgrade I believe Ron refers to is for the higher voltage and capacity demand of the LF100 and subsequent amps with 50V rails.  It will work with the 55, but is not sold for them specifically.

Cheers,

Hugh

[hybride]

At the moment i don't use my GK1 anymore. It's a complete version with remote control and input board.
The GK1 has some of the modifications written in this threads. A marvelous pre-amp. The best and most musical i ever had.

If someone is interested to take it over, send me an PM
 

[andyr]

At the moment i don't use my GK1 anymore. It's a complete version with remote control and input board.
The GK1 has some of the modifications written in this threads. A marvelous pre-amp. The best and most musical i ever had.

If someone is interested to take it over, send me an PM

???  So, hybride, if it's "the best and most musical (preamp) I ever had" why are you no longer using it? 

Regards,

Andy

[hybride]

Hi Andy.
Less is more, i believe. But sometimes that rule doesn't bring the best. My beloved TDA1541 DAC project always needed a pre-amp to get a full body sound. Without pre it sounded 'thin' in de mids and the lows. We did more modifications in the output stage of the DAC. Now the DAC sounds better with direct coupling to my LF100 amp. There is a little more resolution with direct coupling, but, i have to admit that with the Pre there is some beter 3d presentation. While i only use the DAC as source, i have decided to go on without pre.
 

[andyr]

Hi Andy.
Less is more, i believe. But sometimes that rule doesn't bring the best. My beloved TDA1541 DAC project always needed a pre-amp to get a full body sound. Without pre it sounded 'thin' in de mids and the lows. We did more modifications in the output stage of the DAC. Now the DAC sounds better with direct coupling to my LF100 amp. There is a little more resolution with direct coupling, but, i have to admit that with the Pre there is some beter 3d presentation. While i only use the DAC as source, i have decided to go on without pre.

Different strokes ... as they say!   

I have 3 sources but I also like the result of the tube output stage in my GK-1R with my LF amps. 

Regards,

Andy

[guest1632]

West,

I strongly support Steve's POV here;  the only cap that really seems to make a difference is the input cap, C1, though the output coupler (the yellow Auricap) will have a discenible effect but can simply be enhanced with a teflon bypass, say 0.1uF.

That input cap is VERY influential, as an appreciable AC current does pass through it.  The interstage coupler, C19, drives only a tube grid, and passes no current.  The polystyrene supplied is a very good cap, tiny too, and can't much be improved upon.

The GK1 as it stands is capable of extraordinarily high performance sonically, out of all proportion to its relative simplicity, and I have been trying for six years to improve on this circuit with very little success. 

Hope this helps, and thanks Steve for your input,

Cheers,

Hugh

Hi Hugh,

Never know where I'll pop up. heheh, so could you then eliminate C19, and have the stages direct coupled?

Ray Bronk

[guest1632]

Hi,

Hugh, if the tantalum works that means I have to change my board from ugly to colorful.  Aren't the tantalum usually colored in pastel?  I don't have any tantalum to compare to the Solens.  Can't wait to hear from others on how amazing this change is.

Cheers,
Philip

Hey Philip,

What were the original values of the caps on C4 and C7? Also, you said you changed some resistor values?

Andy, if the original values were smaller than the 47UF, (yep, big caps) that in itself would explain the difference in sound.

Ray Bronk

[guest1632]

Hi Mark,

Possibly, but I have to be damn sure it betters the original design.

That said, I ALWAYS check these things.  And I have a few ideas of my own, nuttin' stands still......

'We pursue a policy of continuous improvement, and make no apology for it, so there......  '

Hugh

Ah another perfectionist, just like myself.

So what do these changes actually do. What is the purpose of the LED? also the change in resistors what do they do?

  * Use the LED from L1 in the C4 position.
  * In the spot where the LED was [L1], use a cap. [I presume this is where Philip has used the Solen since he's also using the "ginger LED mod".]
  * Change R13 to 470 ohm
  * Change R14 to 10 kohm.


Ray Bronk

[guest1632]

But Darren,

Do you really need 200w into 8 ohms to power your speakers ... given that you've got a sub and so I suppose have rolled off the low end? 

Regards,

Andy


I didn't really need the worked V8 I had 20 years ago either ... but I still miss it. 

True, my speakers are an easy load though only 83db or so .... but if I could have double the power without giving anything up ...

Besides that first watt, more power means to drive the speakers with less stress or effort, thus providing more sound goodness.

Ray Bronk