Simple GK-1 Tweak

stvnharr · « **Reply #40 on:** 22 Dec 2006, 07:34 am »

Quote from: andyr on 22 Dec 2006, 03:21 am

Quote from: stvnharr on 21 Dec 2006, 10:08 pm
Here's something new on the subject of capacitors for eveyone to mull over -

http://www.vhaudio.com/21capacitorshootout.pdf

It's just one person's view and opinion of course. But it seems reasonable.

Great article!!

Regards,

Andy

One thing I have noticed to be in common with all the rave opinions on the V-Cap is that they all are using them in tube amps and preamps, all tube-o-philes. Nevertheless, the GK-1 does have the tubed output stage.

I did like the article as the writer listens to much the same music as I do, and used the caps in his preamp.
It's a good read.

RonR · « **Reply #41 on:** 30 Dec 2006, 03:41 pm »

Quote from: stvnharr on 20 Dec 2006, 03:56 am

Be interesting if any one else, other than Peter, has had experience with teflon caps in the GK-1.

Well, I bought my GK-1 a Christmas present!

Old Caps:

C1 Multicap RTX 470n 400V
C19 Multicap RTX 10n 400V
C21 Multicap RTX 1uf 100V

New Caps:

C1 V-Cap OIMP 2uF 250V
C19 V-Cap TFTF 10n
C21 Multicap RTX 1uf 100V bypassed with Multicap RTX 10n 400V

Value of C1 was chosen with respect to Hugh:

Quote from: AKSA on 21 Jul 2005, 10:56 pm

Concerning teflon Venhaus caps, I have tried them and my one concern is a perceived lack of bass. In some situations, active systems for example, this can be an advantage, but in a full range amp it could be an issue. It's difficult to try before you buy, but I'd go for around 2.2uF rather than 1uF on the input to offset the bass issue.

After only a few minutes, I seem to be getting a flavour of what the V-Caps will deliver, namely detail, air, and an almost onion-like layering effect. The bass frequencies don't seem to be a problem at all.
Now I just have to wait another 200-400 Hours to get the full benefit.

I'll give a more detailed impression at 50 hours or so.

A Happy New Year to all Aksaphiles.

Cheers,

Ron

AKSA · « **Reply #42 on:** 30 Dec 2006, 09:33 pm »

Thanks Ron!!

These caps, which are rated to 400V for tube applications, are used in the GK1 to around a quarter volt on the input, and 50V on the output, so they are HUGE compared to the stockers supplied, even the Auricap. If you can fit 'em in, they would certainly add something, but GROAN, the COST......

A very Happy New Year to you, Ron, and to all other AKSAphiles. We humans live in hope that the next year will always be better - we are all hopeless optimists!!

Cheers,

Hugh

stvnharr · « **Reply #43 on:** 1 Jan 2007, 12:20 am »

Ron,
Thanks for sharing that. Nice to hear that you've had similar results with teflon caps.

Steve

RonR · « **Reply #44 on:** 27 Jan 2007, 01:42 pm »

Hi Aksaphiles,

Time to comment on the V-caps now they're settled in. Here's an extract from a PM sent to TimS:

The V-Cap substitutions that I carried out on the GK-1 were a great success. I chose the oil impregnated metallized polypropylene (OIMP) V-caps for C1 (replacing Multicaps), with TFTF Teflon V-caps for C19 due to size, voltage and expense considerations.
I used the old C19, a 10nF Multicap to bypass the 1 uF Multicap I already had at C21.

The impression I get from the modifications are of naturalness and superb detail. Orchestral works and acoustic recordings seem to benefit most. Maybe that's because more 'spatial' information is getting through to the speakers?

Please bear in mind that my GK-1 has been heavily tweaked, so your results may vary.

After the GK-1 had settled down a bit, I replaced C1 on the LifeForce with a V-cap 1uf OIMP (Photo in gallery here). This has not been a total success so far. The Bass, although very tuneful, seems to 'Come and Go' depending on which CD I listen to. However, the Mids and Highs are excellent, so I'll persevere with this until a few hundred hours have elapsed to see how it goes.

Cheers,

Ron

AKSA · « **Reply #45 on:** 27 Jan 2007, 10:28 pm »

Ron,

Many thanks for sharing. This is really interesting, showing that the capacitors have profound effect on the sound, much of this effect immeasurable by other than the human ear.

I'm surprised the oil impregnated caps worked so well; these caps are known to confer coloration, and while this is used to good effect in some tube amps, the GK1 is such a low distortion beast that I would have expected non-oilers to be best.

However, I love diesel engines, so I might try them in time, too!

The Sonicap Platinum series is very good, according to Steve Harrison, and I intend to try it myself soon. The VH caps are pretty expensive, but clearly the cat's meow. To my ears, by far the most important cap on the GK1 is the tube grid coupler, the 10nF. This cap is small enough that its replacement is relatively cheap, compared to the 1uF behemoths necessary at the front end and output!

Great Xmas present!! Happy New Year!

Cheers,

Hugh

RonR · « **Reply #46 on:** 1 Feb 2007, 10:47 pm »

Hugh,

Your last post prompted me to do some more listening, and I must say that I can't detect any colouration with the OIMP V-caps. There's certainly an increase in detail, but what is more noticeable is a sort of 'Texture' to the sound. I'm not very good at describing these things, but here goes: It's not the kind of detail that reveals multiple instruments, but detail within an instrument's sound. Things like trumpet blare, rasping voices, and wood resonances seem more 'real' than before.

BTW I don't share your feelings for diesel engines, could this be something to do with your childhood on the Farm?
Mine have to be High-Octane Petrol jobbies, breathing through multiple carbs to give that induction roar!

Cheers,

Ron

stvnharr · « **Reply #47 on:** 1 Feb 2007, 10:48 pm »

Well, after nearly 2 months with the Platinum cap, the music just keeps getting better and better. My GK-1 is pretty heavily tweaked, but this one change is by far the most effective to me. I highly recommend that anyone with a GK-1 should change the C19 cap to either a Sonic Platinum or VH Teflon. This is an easy swap as the size of the caps is about same and easily fits on the board.

I currently have some larger Platinum's coming to experiment with at the input and/or output couplers, and will report on that in due time.

gsb · « **Reply #48 on:** 4 Feb 2007, 05:23 am »

If I change C19 with a V-Cap TFTF, does the polarity matter?
Red wire toward the output?

AKSA · « **Reply #49 on:** 4 Feb 2007, 05:36 am »

Hi GSB,

Shouldn't matter, but some cap manufacturers like you to follow their lead.......

Shouldn't red be to the positive DC? In which case red to tube, non-red to output.

Cheers,

Hugh

gsb · « **Reply #50 on:** 4 Feb 2007, 04:43 pm »

You mean red wire closest to C18?

AKSA · « **Reply #51 on:** 4 Feb 2007, 08:54 pm »

Yes, Greg, that is, closest to the word LINK. This is the cathode connection.

Cheers,

Hugh

PSP · « **Reply #52 on:** 5 Feb 2007, 10:53 pm »

GSB,
I know that Chris VenHaus has posted on the preferred VCap orientation. I think it was on Audio Asylum, and I think I've got a print-out lying on somewhere within a big pile o'crap beside my workbench. I'll look for it tonight and get back... maybe if you search AA, and I serarch my basement, one of us will hit paydirt.

Good luck,
Peter

PSP · « **Reply #53 on:** 6 Feb 2007, 12:11 am »

GSB,
Here you go: http://db.audioasylum.com/cgi/m.mpl?forum=tweaks&n=134385&highlight=v-cap+lead+direction+ChrisVH&r=&session=

Let us know how it sounds!
Peter

AKSA · « **Reply #54 on:** 6 Feb 2007, 12:14 am »

Thanks Peter,

On this basis, Greg, red lead (innermost foil) is to tube cathode, green lead (outermost foil) is for signal output.

The correct orientation would have implications for shielding - and thus low noise and hence resolution.

Cheers,

Hugh

gsb · « **Reply #55 on:** 6 Feb 2007, 04:03 am »

Thanks for all the help Peter and Hugh,
do you want to know how it sounds before or after the 400 hours of break in?
If after,I will get back to you around June.

Greg

AKSA · « **Reply #56 on:** 6 Feb 2007, 08:26 am »

Greg,

Thanks for asking - I want to know how it sounds the whole way through!!

Whenever you want to tell us, we will be listening.......

Cheers,

Hugh

PSP · « **Reply #57 on:** 6 Feb 2007, 03:07 pm »

GSB,
I have not gone the V-Cap route, yet. Building Orions and buying two 55LFs has captured my focus and finances of late.

Initially, I was pleasantly surprised what a few relatively cheap film caps could do for the GK-1, then I bypassed a couple of those with Teflon Rel-Caps (TFT), was temporarily very satisfied with the results and have not done more. Steve Harrison's results with VCaps and Platinum Sonicaps motivate more work on this.

Please let us know what you find out. I'll be following your results very carefully.
Peter

PT914 · « **Reply #58 on:** 7 Feb 2007, 05:17 am »

Hi,

Hugh knows best and is right about C19. Recently changed C19 to 10nF V-caps. The V-cap came from the input caps for the 25N+ amps I was using for the Orion tweeters that were switched to LF55s. They were well burned in and made a big difference in sound. Crystal clear high, mids, everything. Big sound stage, gaining height.

Was so impressed with the changed, I started questioning my choice for C1. Had 22 uf BG, then 1 uf RTX, then most recently 4.7 uF Aeon. When back to 1 uF RTX and bypassed with new 10 nF V-caps. They are burning in for two weeks. I am impressed with the apparent better bass. The improved highs must contribute to better attack of bass notes. Sound stage is also bigger and very dependent on right and left balance in recording. Anyway, this combination at C1 is less costly than a 1 uF V-cap, and it's sounding way better than previous caps tried.

In prior tweaking, I found if C8 is changed to a more exotic cap, sound is sweeter.

The GK-1 preamp is such a great product. Sounds good stock. Very tweakable, you just need alot of room above and below the board for big caps.

Happy listening,
Philip

MikeC · « **Reply #59 on:** 7 Feb 2007, 06:46 pm »

At Hugh's suggestion, I have ordered a 22nF Teflon cap pair for C19. I also started worrying about the 10K input impedance of the Orion crossover, so I have also ordered a 4.7uF pair of Mundorf ZN polyprop film and foil caps for C21. These will be bypassed with 33nF Teflon caps. I currently have 2.7uF Mundorf ZN caps bypassed with 22nf Teflons for C1, and am very happy with them. There is no way that I could put Teflon caps in any of these positions at the full value. I also have a Mundorf at C1 in my midrange amp (0.33uF) and a Relcap TFT at C1 in the tweeter amp (47nF) in my Orion setup, and have largely avoided the burn in problems I had previously with BG's at C1 in my original AKSA 55N+. I can't assign sound to any particular cap as the whole system is now new, but I haven't been immune to burn in. However, the system is now starting to open up again, after going from somewhat steely sounding to comparatively veiled and closed in.

Cheers

Mike