GK1 Platinum and BEYOND.......

AKSA · « **Reply #40 on:** 30 Apr 2007, 11:36 am »

Jens,

Thank you so much for your perseverance. This has been an epic battle. I too am involved on this front, as you know, and still forging ahead. It is very frustrating, because I've built many of these preamps and this is the first that's really been a problem.

Interestingly, even with the output shorted to ground, there is still hum!! This tells me the problem could be ground reference, a weird one indeed....

Cheers,

Hugh

Jens · « **Reply #41 on:** 30 Apr 2007, 06:34 pm »

Hi Hugh,

Still hum when output is shorted? Really weird! Could be the interconnect, then?

Jens · « **Reply #42 on:** 3 May 2007, 11:39 am »

Well, I have now had a chance to listen a bit more to the "Platinum" upgrade of my GK-1R. I have not yet re-implemented the Relay board, and fortunately everything is still really silent!

Except when playing music, of course

Anyway, I had an audio friend over for a few hours the other day, and we listened to music more or less all the time he was here. This also meant I got to play some very well-known tracks again, which made it fairly easy to make comparisons between "pre-Platinum" and "post-Platinum" sound. I should also mention that I do not believe that the Platinum caps are yet burned in.

However, already now I can safely say that there are things to be had with this upgrade. Listening through a large variety of music the other day, the first thing that struck me was a smoothness that I did not hear before. It is not the kind of smoothness that glosses over and blotches out detail - detail is retained, and indeed to some extent improved.

Also, as mentioned before, there is noticeable more "slam" in the bass. But not only more slam, also more precision. Perhaps bass is also a bit more weighty, but I'll need to listen a little more to verify that.

Coming back to the smoothness, this also extends into the high octaves in a very pleasing manner. As a result of this, spatial information is also improved to some extent - and this was absolutely excellent as it was!

The above could sound as if the improvements are fairly small. I don't feel they are. In fact, I would say they are improvements that are well worth the investment into the fairly expensive Platinum caps. Also, I don't feel that implementing the Platinum caps changes the inherent GK-1 sound, it merely brings it to another level

I have yet to implement "The simple GK-1 tweak" for C2 from PSP's thread, but this will be done in a not too distant future (have to get hold of the caps for this).

For now, I'll just keep playing and enjoying music from my upgraded GK-1R and see what happens when the caps settle in

PSP · « **Reply #43 on:** 3 May 2007, 01:13 pm »

Gentlemen,
My initial motivation to modify at C1 and C2 was based on SL's preamp recommendations for the Orion. (I suppose) in order to reduce phase errors at 20Hz, he recommends that the preamp be good down to 5Hz. When I asked Hugh for advice, he recommended that C1 be increased to 2.2uf "a good film cap" and that C2 be increased to 33uf "a good electrolytic". When I made the changes I expected deeper/better bass but was surprised to hear significant improvement across the board, especially in the highs. Just as Jens says, the underlying character of the GK-1 remains, only more better

. Since then, Steve has pushed this mod to an entirely new level and at some point I will be following his lead with the Sonicap Platinums.

However, I should point out that I changed C1 and C2 at the same time, so I don't know what the sonic impact of change at C2 alone might be (other than Hugh's initial suggestion that it might help extend the bass).

Peter

Jens · « **Reply #44 on:** 3 May 2007, 01:26 pm »

Hi Peter,

Good point! Obviously, it's difficult to know how much comes from the improved C1 cap and how much from the improved C2. However, since the "lid is off", I thought I can just as well include the C2 in my upgrade scheme - it certainly won't hurt.

I will try to use a BG NX 33 uF, if possible. However, it does not seem to be available at any higher voltage than 16 V. Does anyone know how much voltage C2 needs to be able to tolerate? Hugh?

Peter, hope your Orion adjustments are coming along nicely

fajimr · « **Reply #45 on:** 3 May 2007, 02:17 pm »

Hi Jens

o.k. o.k. you've got me salivating for the mods to my GK-1 and I haven't even begun the build yet!

But maybe I'll just do it from the start as it seems to make a nice difference...

quick question though: did you integrate all SL's mods?

C1 - Sonic Cap Platinum 1 uf, could also use .47uf
C19 - Sonic Cap Platinum .01 uf
C21 - 1uf Mundorf Silver /Oil or Dynamicap
- 1uf Auricap, the stock cap

I didn't see a specific reference to exactly what you were doing.

thanks
jim

Jens · « **Reply #46 on:** 3 May 2007, 02:43 pm »

Hi Jim,

I implemented a Sonicap Platinum 1 uF for C1 and a Sonicap Platinum .01 uF for C19. C21 is still the Auricap. I tried implementing a .047 uF Sonicap Platinum for C21, but got hum, most likely because of the large change in value from 1 uF to .047 uF. It seems with this low value hum might get in through my unshielded interconnects between the GK-1R and the LF55. I'm going to try with shielded interconnects at a later stage ......

The change of C21 from 1 uF to .047 uF was intended to create rollof for my treble/mid system at around 250 Hz.

fajimr · « **Reply #47 on:** 3 May 2007, 03:04 pm »

thanks jens!

ginger · « **Reply #48 on:** 4 May 2007, 06:38 am »

A short note on handling "shields" on capacitors. Many caps have a "shield" end - that being the connection to the outermost plate or foil winding etc depending upon construction of the cap. It therefore has some shielding action - hence the name

To maximize this shielding action and to better drive any leakage capcitance to surrounding parts the shield end should always be wired to the capacitor circuit pad which sees the lowest impedance back to signal ground.

On a GK1 analog board input, the input Z is 47K'ish - the drive from a CD player etc (REGARDLESS of whether it comes via a relay switch board or a manual switch) is likely to be less than 10K so wire the "shield" end to the signal input connector end with the other end feeding the base of that first transistor

On the tube buffer stage input, again the actual tube input is a higher impedance than looking back into the volume control so the "shield" goes to the volume control input side.

On the GK-1 tube buffer output, the tube output impedance will be lower than the input impedance of whatever power amp you hang off the output so in this case the "shield" side goes to the tube cathode and the other side goes to the output socket.

I learned this from building valve (tube non Oz and UK types) amps. In all of my valve amps the coupling cap "shield" side goes to the driving stage anode and the non-shield side goes to the grid of the next stage valve.

Cheers,
Ginger

Jens · « **Reply #49 on:** 4 May 2007, 08:49 pm »

Thanks, Ginger! Very good input! All GK-1 owners wanting to upgrade should be able to take advantage of this!

fajimr · « **Reply #50 on:** 17 May 2007, 06:21 pm »

just ordered my platinum caps... couldn't resist

going through the build right now... gotta say (again) that hugh's instructions are excellent.

Everything is going smoothly!

jim

DSK · « **Reply #51 on:** 13 Sep 2007, 10:36 pm »

Well, I finally got around to upgrading the caps in my GK-1 about 5 weeks ago and have around 400 hours on it since then.

Specifically, the upgrades were:

C1, C19: replaced with Sonicap Platinums
C21: added a Sonicap Platinum bypass cap across the existing Auricap
C2, C4: BlackGate N/NX

The improvements were fairly evident immediately and opened up a little more over the next few weeks...

Quieter noise floor, greater transparency
More ambient/acoustic info
Greater inner detail (especially evident in bass chords)
Tighter, cleaner bass
Less mechanical sounding, more natural/organic/musical/real
Instruments with complex harmonics sound more realistic (piano, violins, cellos, basses etc)
Soundstaging has a little better dimensionality
More nuance in voices
More realistic and sweeter upper mids & treble

Individually, each improvement is subtle, but the overall improvement is well worth the money and effort IMHO. For a few hundred dollars it takes the GK-1 up another notch. I haven't heard any A$10k+ pre-amps but my GK-1 easily matches all pre-amps I've heard up to A$7500. Though I wouldn't go so far as to describe the scale of improvement as being equal to a major component upgrade, I think it would be fair to say that it was equal to a minor component upgrade.... and for anyone eager to glean every last iota of performance from their system, that's not bad for a few hundred bucks!

It had already been modded with TKD 2P65S stepped attenuator (http://www.thlaudio.com/indexE.htm) & Vishay S102 bypass resistors, Vampire OFC RCA's, twin grounded shielding plates, Dynamat Extreme damping material on chassis, damped PCB mounts, NOS Siemens gold pin 7308 tubes, no source switch in signal path, etc.

Every time I think that I've got the very best that Hugh can do, the bugger comes up with something better. So, I know I shouldn't do this but ...

Hey Hugh, I challenge you to come up with something even better!

AKSA · « **Reply #52 on:** 14 Sep 2007, 12:48 am »

Thanks Darren,

Thinking all the time.....

But also thinking about more sales!!

I hate that part of it, seems somehow messy, not pure, like the engineering......

And there lies the rub.......

Cheers,

Hugh

stvnharr · « **Reply #53 on:** 14 Sep 2007, 02:12 am »

Quote from: DSK on 13 Sep 2007, 10:36 pm

Well, I finally got around to upgrading the caps in my GK-1 about 5 weeks ago and have around 400 hours on it since then.

Specifically, the upgrades were:

C1, C19: replaced with Sonicap Platinums
C21: added a Sonicap Platinum bypass cap across the existing Auricap
C2, C4: BlackGate N/NX

The improvements were fairly evident immediately and opened up a little more over the next few weeks...

Quieter noise floor, greater transparency
More ambient/acoustic info
Greater inner detail (especially evident in bass chords)
Tighter, cleaner bass
Less mechanical sounding, more natural/organic/musical/real
Instruments with complex harmonics sound more realistic (piano, violins, cellos, basses etc)
Soundstaging has a little better dimensionality
More nuance in voices
More realistic and sweeter upper mids & treble

Individually, each improvement is subtle, but the overall improvement is well worth the money and effort IMHO. For a few hundred dollars it takes the GK-1 up another notch. I haven't heard any A$10k+ pre-amps but my GK-1 easily matches all pre-amps I've heard up to A$7500. Though I wouldn't go so far as to describe the scale of improvement as being equal to a major component upgrade, I think it would be fair to say that it was equal to a minor component upgrade.... and for anyone eager to glean every last iota of performance from their system, that's not bad for a few hundred bucks!

It had already been modded with TKD 2P65S stepped attenuator (http://www.thlaudio.com/indexE.htm) & Vishay S102 bypass resistors, Vampire OFC RCA's, twin grounded shielding plates, Dynamat Extreme damping material on chassis, damped PCB mounts, NOS Siemens gold pin 7308 tubes, no source switch in signal path, etc.

Every time I think that I've got the very best that Hugh can do, the bugger comes up with something better. So, I know I shouldn't do this but ...

Hey Hugh, I challenge you to come up with something even better!

Hi Darren,
Yup, sounds like you've had the same success with the Platinums that I had. The Platinums certainly make all the music better.

Steve

DSK · « **Reply #54 on:** 14 Sep 2007, 09:10 am »

Steve, it is largely your observations that pushed me over the edge. So, I guess it is I that should be thanking you.

stvnharr · « **Reply #55 on:** 15 Sep 2007, 02:06 pm »

Quote from: DSK on 14 Sep 2007, 09:10 am

Steve, it is largely your observations that pushed me over the edge. So, I guess it is I that should be thanking you.

Darren,
I'm pleased that you've found the same improvements as I did.
It didn't really take much of a nudge, did it?
Maybe we both should thank Jeff for designing the cap and making it available to us.

I would hope many others would/will take the big leap!!!!!!!!!!!

Steve

AKSA · « **Reply #56 on:** 15 Sep 2007, 10:35 pm »

Steve, Darren,

Swapped out C1 for Platinum teflons in Raptor's Swift yesterday - I'm hoping he will post here with his observations. For myself, I've noted improvements in transparency and fine detail, well worth the effort but still a little dazed by the cost......

Cheers,

Hugh

raptor · « **Reply #57 on:** 15 Sep 2007, 11:36 pm »

Hi Hugh,

I've only listened to it for a couple of hours, but my initial impression is that it has improved the amount of detail I can hear, and the soundstage seems wider and a little deeper. What has surpised me is that somehow it has improved the bass response I am getting. As you heard when you delivered the Swift to me originally, my system was light on for bass which I put down to speaker positioning and the room itself. This was an area I knew I had to address to get the most out of my gear, but I hadn't got around to experimenting yet.

However as soon as I arrived home and connected the Swift yesterday I put on the Copeland cd we were listening to at your place. The improvement in the bass was quite striking; it had become much more prominent and was now in balance with the midrange and high frequencies, an unexpected bonus.

I will post more when I have had an opportunity for more listening and will try to post the photos that I took when I can work out how to do so here.

Cheers,

Neil

AKSA · « **Reply #58 on:** 15 Sep 2007, 11:58 pm »

Hi Neil,

Wow!! That was quick - thanks for the response!

So, we have more bass, huh? That's a surprise to me, I had not expected more mumbo, and it addresses one of the perceived deficiencies of tube systems.

I'm sheepish about those photos; you caught me in the appalling disarray of my workshop!

The increased refinement and detail is always welcome, what this game is all about. Thanks for your visit yesterday, a pleasure to chat over coffee and walnut slice, and do please tell us how it 'beds' down!

Cheers,

Hugh

andyr · « **Reply #59 on:** 16 Sep 2007, 12:28 am »

Quote from: AKSA on 15 Sep 2007, 11:58 pm

Hi Neil,

So, we have more bass, huh? That's a surprise to me, I had not expected more mumbo, and it addresses one of the perceived deficiencies of tube systems.

Cheers,

Hugh

Hi Hugh,

I thought the "perceived deficiency of tube systems" wrt bass was softening of bass transients ... as shown by the increased bass punch available from the GK-1 "Sub Out", compared to the normal tube out.

Not lack of low frequency extension - which is what I assumed Neil would've been referring to?

Anyway, sounds like I'll be inserting teflon coupling caps in my GK-1 when I've finished my upgrade to Lifeforces!

Regards,

Andy