GK1 Platinum and BEYOND.......

stvnharr · « **on:** 16 Mar 2007, 03:00 am »

Hello All,
I have finished with the cap modifications to the GK-1, as new output caps arrived this week and were quickly installed. I have now christened my GK-1 as GK-1 Platinum, as the Sonic Platinum caps have brought the GK-1 to new heights of audio performance.

The C-1 input Platinum cap has been in the preamp now for just over a month. The sound as reported in my earlier post is much the same, although it does seem as if things have opened up a bit lately to a much broader and wider sound presentation. Every little musical detail seems to be easily heard, with tinkly little things twinkling quickly, whacks being soundly quickly whacked, and notes lingering into long decays.

The new output coupling caps are 1 uf Mundorf Silver/Oils. I had been thinking of 250V VH-OIMP’s as their size was easily accommodated on the board, but in the end I went with the Mundorf’s. They are nearly as large as the Platinum’s, but not as heavy. I was able to fit them on the board, barely.
These caps have made an immediate and noticeable difference in the sound, adding a nice refinement to the pre-existing sound that I heard with the Auricaps in this position.

In summation, the modifications are as follows:
C-1 input cap to SS gain stage – Sonic Cap Platinum 1 uf
C-19 input cap to tube grid - Sonic Cap Platinum .01uf
C-21 output coupling cap - Mundorf Silver/Oil 1 uf

The teflon caps are the single most definable improvement I have ever made to an audio system, more so than even a total unit replacement. This is not just a simple cap modification; it is a total unit sound upgrade of immense proportions. The playback sound of the audio system is taken to a totally new level with these caps.

There also is not cheap way to accomplish this. The 1uf Platinums are $100 ea. and the VH-Audio TFTF’s are 30% more. One may be tempted to just get a small bypass cap as a cheap option. I just don’t think bypassing a signal path cap works. I’ve tried this in the GK-1 and Aksa N+ output couplers and heard absolutely no difference in sound. You need to use the full value cap in the C-1 input cap position!

You have to think of this as a total audio system upgrade rather than a cap change. Thus, the cost of the caps is really a bargain with the sound that results.

Hugh has heard the sound of this modification in my system himself, just a few days ago. Unfortunately the new output caps had not yet arrived, but they are more like icing on the cake. He’s heard the improvement the Platinum teflons make to the sound. You can contact him direct for his personal opinions, impressions, and thoughts.

Finally, if you have a GK-1 and want to take it to the ultimate level of sound reproduction, the teflon cap modification is a MUST. You cannot do anything else to the unit, or your system really, with as much impact as this modification!

Steve

AKSA · « **Reply #1 on:** 16 Mar 2007, 04:12 am »

Thanks Steven, your observations and comments much appreciated.

The addition of Platinum Sonicaps, made with teflon dielectric, takes the GK1 to the pinnacle of transparency. I have heard nothing better with the Lifeforce power amplifier, but then audio memory is so poor that one really needs AB testing to be definitive. But there is no doubt that if that was good, with the Mundorf on the output coupler the sound would be absolutely the last word in natural, dynamic and resolving sound.

However, one must be circumspect. The cost of these caps, up around $US100 for the Sonicaps and not much less for the Mundorf Supreme silver/oils, adds a cool $US350 to the price of admission. For a kit, this is fantasy land, but for many audiophiles it's short term pain driven by the infamous, compulsive 'need to tweak'. I appreciate the opportunity Steven gave me to hear this, I would not by myself have done the mod for purely economic reasons, but here's how I feel......

I will eventully redesign the SS section of the Swift, the non-kit, fully built Aspen preamp, to exploit the teflon caps. I have spent many long hours musing on circuit configurations and ways of reconfiguring the input stage to use much smaller caps, so as to minimise the cost of any teflons I use. This could take a LONG time!!

But I won't be releasing teflon caps for the kits, that is for certain!!

Thanks again, Steve!

Cheers,

Hugh

stvnharr · « **Reply #2 on:** 16 Mar 2007, 07:13 am »

The total cost of the caps I installed is around 300 USD plus shipping. This seems a lot for caps, but it's not much for what you get in return.

If you forgo things like NOS tubes, replacing electro caps on the SS stage, and a fancy attenuator, you can get the caps and maybe have money left over.

I realize there aren't many GK-1's out there, and many, if not most, already have numerous modifications. Do the caps, or at least the C-1 cap. You will be very pleased!

DSK · « **Reply #3 on:** 16 Mar 2007, 09:20 am »

Steve, Thanks for sharing. .....MUST resist ....MUST resist ....MUST resist

What did you settle on at C2?

stvnharr · « **Reply #4 on:** 16 Mar 2007, 12:29 pm »

Darren,
I think C2 is the .47uf BG that Hugh gave me last year.

Don't resist!!!!

Steve

fajimr · « **Reply #5 on:** 16 Mar 2007, 12:34 pm »

thanks steve

I was planning on re-reading all the old posts to see what the final word was- probably still will, I appreciate the Cliff Notes version (and for all those not in the US or out of school for some time- Cliff Notes are the popular series of pocket books which summarize important intellectual works. Think of it like an academic "for Dummies series" please note that I am not knocking them, they can provide a good introduction but should not replace the original). now just need to find time to build it

jim

DSK · « **Reply #6 on:** 16 Mar 2007, 02:22 pm »

Quote from: stvnharr on 16 Mar 2007, 12:29 pm

Darren,
I think C2 is the .47uf BG that Hugh gave me last year.

Don't resist!!!!

Steve

I think the original C2 was a 10uF/16vw tantalum cap. PSP uses a 33uF BG NP, while AndyR uses a 22uF BG NX. Any reason you went with .47uF or was it just availability?

Fight.....ing ....temp.....tation ....must .....be.....strong.

MikeC · « **Reply #7 on:** 16 Mar 2007, 07:15 pm »

I don't have the large value Teflon caps (too expensive), but here's what I have done:
C1 = 2.7uF Mundorf ZN Polypropylene film & foil bypassed with 22nF Relcap TFT
C19 = 22nF Relcap TFT (increased value at Hugh's suggestion)
C21 = 4.7uF Mundorf ZN Polypropylene film & foil bypassed with 33nF Relcap TFT

As noted, Hugh suggested increasing C19 to 22nF if I was inserting a Teflon cap, and the C1 and C21 values were increased to maximise bass performance. With the stock 1uF value for C21, the f3 into the Orion crossover was around 16Hz, it is now about 3.5Hz.

C19 and C21 have just been changed, and I can't really give full comments on the sound quality as I haven't had the time to listen for much more than a couple of hours yet. However, there is a degree of bass power and openness that was never there before. I guess that things will open up further, but I am also hearing improvements similar to those Steven has commented on. The more powerful bass (to be expected) and an increased purity are pretty obvious.

I will post more comments when I have had a chance to listen further and get some run-in on the caps.

Cheers

Mike

Jens · « **Reply #8 on:** 18 Mar 2007, 11:57 am »

After reading all the threads on upgrading the GK-1 (and getting somewhat confused about what to do), it's very relieving reading this thread that you guys come up with

There seems to be widespread consensus that the teflon caps are the caps to use for C1 and C19, but I'm wondering if a teflon cap would not also be the ultimate cap for the C21? Comments, anyone?

My first inclinination was to go with a Mundorf Silver/Oil at C21 (like Steve), as I have very good experiences with these, but if a teflon cap would be even better, then why not? (and caps could be ordered from one source

)

Did anyone experience any downside with using a teflon cap at C21?

At any rate, in my case the value of this cap would be around .033 uF, as I will use this cap to roll off the midrange, which is driven from the tube output, so the cap won't be too big and expensive. In conjunction with the midrange driver's own acoustic rolloff the cap rolloff introduced in this manner should give a very nice, sharpish rolloff. I used this type of rolloff in my previous preamp where it worked beautifully.

stvnharr · « **Reply #9 on:** 18 Mar 2007, 10:29 pm »

Hi Jens,
I used the Mundorf cap for the output cap for 2 reasons:
1. Size, the 1uf Platinum is too big for the board here as there is not enough room underneath for it, so would have to mount off board and use flying leads

2. Cost/value of diminishing returns. The C1 Platinum opened up so much and the sound was so good even with the Auricap that I thought the large cost for the Platinum would not bring the same benefits as at the input. The Mundorf, while not exactly cheap at 38 USD seemed the most reasonable choice, especially as they are Jeff Glowacky's favorite cap after the Platinum's.

Jens, if you are going to use a .33uf teflon cap there should be no size issues on the board. Teflons I think are most certainly the choice for signal path caps if they fit and the money is okay.

Steve

Jens · « **Reply #10 on:** 19 Mar 2007, 08:41 am »

Hi Steve,

Thank you for your input on the output cap

Size is certainly an issue, as there aren't unlimited amounts of space on the GK-1 board, and there's certainly a huge difference in price on the 1 uFs, so I understand your choice.

Not so when you go for .033 or .047 uF. Mundorf and Sonicap prices and sizes are almost identical for those values - looks like I'm in a bit of luck there

Guess I'll smash my piggy bank and see if it contains the 275 USD that these caps will set me back

stvnharr · « **Reply #11 on:** 19 Mar 2007, 09:24 am »

Hi Jens,
You should find that the teflon caps, especially the big C-1 cap will be a transformation. It sure was for me.

Steve

Jens · « **Reply #12 on:** 19 Mar 2007, 10:37 am »

Hi Steve,

I'm certain it will be. People in here tend to have good ears

Most likely, I'll be ordering the caps today!

AKSA · « **Reply #13 on:** 19 Mar 2007, 11:24 am »

Oooooooooooooooohhhhhhhhhh,

You guys will all have better GK1s than I've got!!

Hugh

Jens · « **Reply #14 on:** 19 Mar 2007, 02:41 pm »

Well, Hugh - you could update your own GK-1 along the same lines .....

But why not look at it i another way - you've got a whole bunch of people here who love your products so much that they feel they have to bring them to the sublime. I that was me, I would be very proud and happy (and I think you are just that!)

Must rush ..... have to order my teflon caps

Seano · « **Reply #15 on:** 19 Mar 2007, 09:18 pm »

Hmmmm.....US$97.80 (1uf) and US$17.80 (0.01uf)for the Sonicaps http://www.soniccraft.com/sonicap_platinum.htm plus another AU$47 for the Mundorf http://www.soundlabsgroup.com.au/c/Mundorf-Silver-Oil/Mundorf+Silver+Oil.html

That's about AU$200 plus postage......s'not too bad I suppose. But you wouldn't want to stuff up that 1uf Sonicap.

Or show it to the missus.......

Jens · « **Reply #16 on:** 19 Mar 2007, 09:51 pm »

Seano - good luck with sneaking them in under the wifey's nose

Seano · « **Reply #17 on:** 21 Mar 2007, 03:06 am »

"Sorry sweetie! The stereo is busted at the moment and I'm just getting this replacement part - you know I've explained to you before about the guy who I got the kit from likes to charge big time for the individual parts.........well this one's a bit more expensive than most....and there's just no other alternative [shrugging hopefully]"

LM · « **Reply #18 on:** 21 Mar 2007, 04:06 am »

Problem is if your wife ever saw Hugh at say a party, he might really cop an earful. Alternatively, you could ask Hugh to spec up a GK1 Platinum Super upgrade kit with V-Caps or whatever specified in every possible position. Then you explain how reasonable your modest your $200 upgrade plan was compared to that outrageously priced audiophile upgrade kit. Only problem is, Hugh would then be safe at the party but he might gain a bit of notoriety on the net for having the world’s most expensive preamp kit.

Jens · « **Reply #19 on:** 21 Mar 2007, 06:56 pm »

Seems there's no limit to what lengths we audio buffs will go to to upgrade our beloved systems

Meanwhile, I have ordered my Platinum caps and await their arrival eagerly