GK1 Platinum and BEYOND.......

whubbard · « **Reply #100 on:** 10 Mar 2008, 11:12 pm »

alrighty, so no C2, C4.

For C1, Hugh recommends a 2.2uF cap so that it can go down to 5hz. What do you recommend for a 2.2uF high quality cap, or do you think that its not worth going to 2.2uf, and that I should just stick with the 1.0uF.

For 21, I might consider the Auri-T bypass, but is there a cap that will improve the sonics, but can be replaced into the board without long leads (ie...it fits the board?)

Thanks

stvnharr · « **Reply #101 on:** 11 Mar 2008, 12:05 am »

Quote from: whubbard on 10 Mar 2008, 11:12 pm

alrighty, so no C2, C4.

For C1, Hugh recommends a 2.2uF cap so that it can go down to 5hz. What do you recommend for a 2.2uF high quality cap, or do you think that its not worth going to 2.2uf, and that I should just stick with the 1.0uF.

For 21, I might consider the Auri-T bypass, but is there a cap that will improve the sonics, but can be replaced into the board without long leads (ie...it fits the board?)

Thanks

Hi,
It's just my opinion that cap changes on C2 and C4 make no difference. I think I have some kind of Black Gate at C2, and have had a couple different ones at C4. They never seemed to make any difference to me. Teflons at C1 and C-19 trumped everything!

Hugh recommended the 2.2uf cap at C1 before he heard my Platinum modifications. The only thing equal or better than a teflon cap at C-1 is a bypass wire. With a teflon cap you have no safety worries of stray dc. Both the 1.0uf and .47uf caps are large and don't fit on the board. Just mount them as input wires and use wire link across the C1 space on the board.
For C-21, there is no replacement cap that fits the same size on the board. I've got some huge Mundorf cap there, mounted off the board with long leads to the board. I didn't really hear any difference with it from the auricap or dynamicap I had used previously. That's why I like the small teflon Auri-T as a bypass as it can be mounted on top of the stock Auricap. It likely won't make much difference, but will give you the feeling that you've done something and improved it by doing so.

Steve

AKSA · « **Reply #102 on:** 11 Mar 2008, 12:41 am »

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

whubbard · « **Reply #103 on:** 11 Mar 2008, 06:40 am »

Well, it seems like it will just be the C1 for me then.

Thanks for the help!

kyrill · « **Reply #104 on:** 11 Mar 2008, 11:26 am »

forgive me for saying it so often
the C1 cap is coupled to the output cap of the apparatus in front of it.
a dedicated C1 cap makes the function of the output cap prior to to the C1 useless
so remove it as it will (serious) degrade the sound unless it is also a hugely expensive film teflon cap but will still sound less than a straight wire

whubbard · « **Reply #105 on:** 11 Mar 2008, 03:41 pm »

Isn't putting a straight wire there a bit dangerous?
I have not modded any of my sources (yet), and I'm not sure I trust the output caps on the Zune or Sangean.
Do you think its better to replace the output cap on all my sources rather than just change C1?

Also, since I have my GK-1 going right to my lifeforce amps, can I remove the C1 on them too?

Thanks

AKSA · « **Reply #106 on:** 11 Mar 2008, 09:17 pm »

Kyrill,

You are right sonically. Deleting C1 will improve the sound. BUT, a teflon will be so close that there's not much in it.

You are uncompromising, and I am conservative. Respectively, that means no cap, and CAP! I really do urge anyone using a GK1 to have an input cap, it's very good insurance and enhances reliability.

How about this? If you want the best possible sonics, it would be more appropriate to keep C1 on the GK1, use a teflon, and dispense with the output cap on the source (CD/DVD/Tuner), which is usually a very ordinary, very downmarket, electrolytic!!

Cheers,

Hugh

kyrill · « **Reply #107 on:** 12 Mar 2008, 10:22 am »

Dear Hugh that is exactly what i am advocating:

"a dedicated C1 cap makes the function of the output cap prior to to the C1 useless
so remove it as it will (serious) degrade the sound unless it is also a hugely expensive film teflon cap but will still sound less than a straight wire"

whubbard · « **Reply #108 on:** 12 Mar 2008, 04:03 pm »

oh.

I think Hugh and I thought you were saying to get rid of the C1 on the GK-1m, not the output cap on my sources.
I agree that it makes the most sense, now for a silly question, will the output cap on my sources be easy to identify?

kyrill · « **Reply #109 on:** 12 Mar 2008, 04:15 pm »

99% yes
mostly it is the first component the signal path connects to WHEN you follow the wire from the rca output plug to the pcb

whubbard · « **Reply #110 on:** 12 Mar 2008, 04:43 pm »

That shouldn't be too hard at all

AKSA · « **Reply #111 on:** 12 Mar 2008, 09:11 pm »

Hey West,

How did you and I so completely misunderstand Kyrill??

I sit, resplendent at my glowing keyboard, corrected.

Kyrill, go to the top of the class. There, you have the floor!!

Thanks,

Hugh

whubbard · « **Reply #112 on:** 12 Mar 2008, 10:32 pm »

Quote from: kyrill on 11 Mar 2008, 11:26 am

A dedicated C1 cap makes the function of the output cap prior to to the C1 useless
so remove it as it will (serious) degrade the sound

I'm not sure how he could have said it any better. Thats me ->

<- Thats Kyrill

Looks like I need to pay more attention...hopefully I won't be this silly when I'm using the soldering iron (or my table saw).

kyrill · « **Reply #113 on:** 13 Mar 2008, 05:29 pm »

Help help
so top up
i dont get air..
no oxygen
scrggrphmg hurcc errh hurcc srccgr noO0 aii r
plz drag me down
to the floor
to the common laymen's floor
i needdd floor aarrghh

AKSA · « **Reply #114 on:** 13 Mar 2008, 10:14 pm »

Kyrill,

Clever students MUST go to the top of the class. Glaring publicity is the punishment for professional success. You are not permitted to sit sullenly in the corner with a funny hat. I can only apologise for not seeing your arguments more clearly before!

You must get used to the high altitude. I include this amusing story for our mutual delectation, and to make you realise your new position:

Quote

A turkey was chatting with a bull.

'I would love to be able to get to the top of that tree' sighed the turkey, 'but I haven't got the energy.'
'Well, why don't you nibble on some of my droppings?' replied the bull. They're packed with nutrients.'

The turkey pecked at a lump of dung, and found it actually gave him enough strength to reach the lowest branch of the tree.

The next day, after eating some more dung, he reached the second branch.

Finally after a fourth night, the turkey was proudly perched at the top of the tree.

He was promptly spotted by a farmer, who shot him dead from the tree.

Moral of the story:
Bull Sh*t might get you to the top, but it won't keep you there..

There are moments when I'm sure this applies to all of us........

Cheers,

Hugh

kyrill · « **Reply #115 on:** 13 Mar 2008, 10:19 pm »

moral of the story

Not every farmer rewards a courageous turkey

AKSA · « **Reply #116 on:** 13 Mar 2008, 10:31 pm »

Or, a more topical, cynical view, fame is accompanied by self-sacrifice........

Hugh

PT914 · « **Reply #117 on:** 9 Apr 2008, 06:48 am »

Hi,

There has been a discussion of future upgrade or evolution of the GK-1. Well I must admit the full potential of the GK-1R has not been reached which attest to the shear talent of Hugh's design. I did the modification that Ginger suggested where C4 is switched with the LED. There was also a change in a few resistors value. I also did the Platinum mod. Well the latest mod I just did with only three hours of burn in has improved the GK-1R the most, by conservatively 3 or 4 times better. High, mids and bass are improved twice over. Imaging is three-D. Center image stage has been pushed back to the wall behind the speaker. The mod is not expensive just ugly. I replaced the super e-cap configuration of C4 with a film cap, Solen 47 uF 250V. It is big measuring 1.5” x 2.1”. I also replaced a BG at C7 with the same cap. Just replacing the two caps with these two monsters did it. You have to find space under and along side the board, but it is amazing how film caps will transform the GK-1R sound and sound stage compared to the BGs. I first tried Jantzen Cross-caps but the Solens are better. There are probably other film caps that sound just as good as or even better than the Solen but I am so satisfied. My GK-1R is not enclosed so I can easy expand things. Hope there is room to expand if yours is in a box.

Happy listening,
Philip

AKSA · « **Reply #118 on:** 9 Apr 2008, 08:14 am »

HI Philip,

Many thanks for your fascinating input. This is seminal stuff, dammit, causes me to rethink my approach!!

C4 is a decoupling cap on the current source which supplies the output stage of the SS section. This section uses a current source T4 of 12.5mA to supply the voltage amplifier device, T3. The most critical aspect of a current source is the voltage reference; it must be rock steady, regardless of any ripple or noise on the rail from which it is powered. This is achieved with a split current feed from the rail to ground, R13 and R14 each of 2k2, and an electrolytic cap which is strung between the rail and the junction of these resistors. Any differential noise appearing between base and emitter of T4 will show as highly amplified noise at the collector of T4, which coincidentally is the output of the SS section and had better be very quiet otherwise resolution is lost. Evidently, by using a large value film cap here, noise is further reduced because diff noise is converted by this cap to common mode noise. That is, noise is identical on both the emitter and the base of the CCS transistor. In essence this means that the diff noise at these sensitive nodes is eliminated, and thus the heavy amplification of the transistor cannot produce single ended noise at the output. This all shows as superior detail and imaging. In fact, imaging IS superior detail; it's the cueing information of the space; footfalls, breathing, instrument noise and other spatial information which is very, very quiet and often lost in the mix.

I have a notion, Philip, that a tantalum here might be as good as a filmcap, AND it will be much, much smaller. It needs to be rated to 16VW, and polarity is important; with positive to the top.

C7 is another decoupling cap which removes noise from the diff pair, again reducing noise at the output and thus permitting more detail to be retrieved.

My golly, I designed this with Darl Singh, bless him (you there, Darl??) in 2002, and still there are improvements being extracted by AKSAphiles the world over!!

Thank you Philip, you've made my day.....

Cheers,

Hugh

stvnharr · « **Reply #119 on:** 9 Apr 2008, 08:35 am »

This is interesting news to be sure. Fitting film cap at C4 and C7 is off the board, and already have a couple of those. But noise reduction anywhere is important as it lets the music through.