GK1 Platinum and BEYOND.......

Oz_Audio · « **Reply #20 on:** 22 Mar 2007, 11:21 am »

Steve, just been reading your plug for all things AKSA on http://www.high-endaudio.com/RECENT.html#Feb

I have been a keen reader of this site for years and have always enjoyed Arthur's forthright observations on all things audio. Good to see he posted your letter.

Now, can someone who knows post a mod thread for all AKSA's , just what they have changed. Please not a pile of words, just where to get the parts, approximate price and a star rating (very objective I know) to the net worth of the mod.

Mark

AKSA · « **Reply #21 on:** 22 Mar 2007, 11:26 am »

Gee, Mark,

That's a tall order!!

Cheers,

Hugh

Oz_Audio · « **Reply #22 on:** 22 Mar 2007, 09:01 pm »

Hugh, I did not mean 1 person.

Anyone who has changed the specifications can post.

Mark

PS where and what is 2007 RMAF?

AKSA · « **Reply #23 on:** 22 Mar 2007, 09:12 pm »

Rocky Mountain Audio Fest, held in Denver CO each year in October.

The best option for the small manufacturer, and the genuine audiophile who is interested to meet and talk with them.

Much cheaper than the CES, specifically set up for the little guys.

Cheers,

Hugh

jules · « **Reply #24 on:** 22 Mar 2007, 10:38 pm »

Mark,

Most of the mods, along with reasons for trying them, are stored right here in the history of this site. Different people ... different mods, so it comes down to reading through it and evaluating what looks good and what looks iffy. It's an interesting read as much for being a kind of living history of Aspen as much as anything else too.

One of the things I rather like about Hugh's circle is that he's allowed all manner of mods to be discussed but keeps his own thoughts on them pretty much to himself though we'd all love to know his opinion

jules

Jens · « **Reply #25 on:** 24 Mar 2007, 08:21 am »

Just got word that my Platinum caps should arrive Monday. Guess I should start heating the soldering iron

This is going to be interesting - hope I won't be so busy at work next week that there won't be time to put in the caps .......

Jens · « **Reply #26 on:** 27 Mar 2007, 06:04 pm »

Platinums arrived right on schedule yesterday

I'm currently planning the "makeover" so I won't have to be without my GK-1R longer than absolutely necessary!

I plan to reroute and shield a few internal wires while I have everything apart anyway, but that shouldn't be too big a deal

stvnharr · « **Reply #27 on:** 28 Mar 2007, 11:20 am »

Jens,
I am awaiting news from you after you have some time with the new caps. I heard a difference from the beginning.

One thing to note is that the large 1uf input cap drops the low cutoff frequency enough so that if one has a subwoofer that goes down to 20hz or so one can sometimes hear low rumbles on old recordings.

Steve

Jens · « **Reply #28 on:** 28 Mar 2007, 04:17 pm »

Hi Steve,

Yep, this is going to be interesting. I will report, of course

I'm aware that increasing C1 to 1 uF extends the "deep end" a bit. Not a bad thing in my book - I love organ music!

One question: On Sonic Craft's homepage it says about the Platinum caps that "The shorter lead is shield". Which lead should preferably go to signal input when inserting the caps?

blizzard · « **Reply #29 on:** 28 Mar 2007, 07:54 pm »

Hi Jens,
The shield (short lead) goes toward the RCA and the long lead goes to the input on the board.

Jens · « **Reply #30 on:** 28 Mar 2007, 10:05 pm »

Quote from: blizzard on 28 Mar 2007, 07:54 pm

Hi Jens,
The shield (short lead) goes toward the RCA and the long lead goes to the input on the board.

Very good - short lead is signal input. Thanks, Blizzard

stvnharr · « **Reply #31 on:** 28 Mar 2007, 11:23 pm »

Hm, I never really took note of lead length, as they looked about the same. I did notice the writing however. Does the path go in line with the writing, S on input and P on output?

Jens · « **Reply #32 on:** 29 Mar 2007, 03:16 pm »

Nah, it's the other way around, actually. The longer lead (output, as it seems) is at "S" and the shorter (input) at "P".

I wouldn't know how much difference it makes in real life - don't even know what theory is behind inputting the signal at the "shield" end of the cap. Anyway, it seems you got a lot out of these caps even though you didn't know what was "right", so I wouldn't worry too much about it, if I were you

Hugh? Anyone? Any thoughts/theories about this?

AKSA · « **Reply #33 on:** 30 Mar 2007, 03:56 am »

Jens,

Shouldn't make any difference, however, email Jeff Glowacki of Sonic Craft and ask his advice.

He's very knowledgeable, and as he sells 'em, he should know.

Cheers,

Hugh

Jens · « **Reply #34 on:** 30 Mar 2007, 06:02 pm »

Hi Hugh,

Very good idea!

I did just that and got a quick reply back from Jeff:

"The idea is that the shield "may" catch some RFI or EMI, so one might
direct the greater source (shield) of "potential" noise to a benign
drain. This drain might be a load resistor such that you would make
the shield the output, but as you suggest, some may prefer the other
direction for one reason or another. It would be circuit/owner
dependent, so that is why we merely convey which lead is which. You
get to make all the decisions. ;~)"

It would seem that soundwise, it may not may make that much of a difference, but that there could be a slight difference in noise. Guess I'll go with the direction of the text, after all

stvnharr · « **Reply #35 on:** 31 Mar 2007, 10:57 pm »

I have now turned my input caps around so as to take advantage of the shielding. I don't use shielded interconnects, so makes sense to take advantage of the shielding in the caps at the input location.
I don't think it makes any difference in the small caps at C19.

stvnharr · « **Reply #36 on:** 27 Apr 2007, 04:18 am »

Quote from: Oz_Audio on 22 Mar 2007, 11:21 am

Now, can someone who knows post a mod thread for all AKSA's , just what they have changed. Please not a pile of words, just where to get the parts, approximate price and a star rating (very objective I know) to the net worth of the mod.

Mark

Mark,
Okay here goes for GK-1:

C1 - Sonic Cap Platinum 1 uf, could also use .47uf ***** a 5 Star MUST
available only at Soniccraft

C19 - Sonic Cap Platinum .01 uf ***** a 5 Star No brainer

C21 - 1uf Mundorf Silver /Oil or Dynamicap **** with the Platinums in place
- 1uf Auricap, the stock cap fits the board, and okay

Gain Stage caps - I have changed most of them to Black Gates, Rubycons, or Oscons in the same values. I didn't honestly hear any difference from doing this. Money is better spent on the above caps.

Tubes - 7308 Amperex 1964 NOS - a nice but small change. *** 3 stars
Get caps first! Stock tubes are quite okay.
Not worth spending a lot of money here, though 7308's are always
expensive.
I purchased from www.vintagetubeservices.com

Attenuators - I use a Goldpoint Shunt 20k attenuator with Vishay S102 for + resistor.
Goldpoint no longer makes kits. Kits only available from Michael Percy
either as ladder or series attenuator.
This may only be ** 2 star as I can't really say I heard anything being
much better.

Rca's etc. - personal preference prevails.

Steve

Jens · « **Reply #37 on:** 29 Apr 2007, 04:44 pm »

I have finally gotten my "Platinum" upgrade to work. And I do say "finally", because it has taken me 3-4 weeks to get my GK-1R back in reasonable working condition after implementing the Platinum caps according to Steven's recipe (apart from one exception).

I haste to add that none of the problems I ran into could be ascribed to any of Steven's advise, make no mistake!

The problems I ran into was hum, hum, hum, and yet more hum!!! Admittedly, I did complicate matters a little myself in that I replaced all signal wiring with my own Equilibrium Cable pure silver wiring at the same time as implementing the Platinum caps.

Anyhow, the first thing that happened after I had put my GK-1R back together, new caps, new wiring and all, I had HUUUUUMMMMMMM! Not devastingly loud, but still loud enough to be heard in my listening position, which is almost 6 metres away from the speakers. The hum was more or less independent of volume setting.

Hmmmm, I thought - this might be because I put the big 1 uF Platinum caps outside the board (in fact, I mounted them with Blue Tack astride two input relays each), causing them to pick up hum. However, moving the caps to the board did not help .....

Do you guys know in how many different ways ground wiring can be done on a GK-1R? Well, during the last 3-4 weeks I think I've tried them all!!!! Also tried various way of earthing (I've got true earth) the preamp. Nothing worked. Hugh and I had some email gander, but none of the things we could come up with worked .....

I won't bore you with all the details of the many things that were tried - suffice it to say that I believe that the main problem has been found. I turned out to be the output cap. Because I wanted to roll off the treble/mid section of my speaker system, which is driven off the tube output, I had reduced the output cap value from the 1 uF Auricap to a .047 uF Sonicap Platinum. Obviously, the latter is a very small size cap, even in the Platinum range, so we are not talking about hum intrusion into the cap (at least I don't think so).

I talked to a tube-knowledgable friend of mine today, who believes that the hum problem I experienced is likely to be caused by the change in the output impedance at the low end of the register, as it becomes easier for hum to be induced into the interconnect between the preamp and the power amp (in my case a LF55) and then possibly back into the rest of the preamp circuits. In my system, this signal wire has always been an unshielded one, which never created problems before. Whether this is the whole story, I don't know ....

I may try out shielded interconnects in this place, but until further notice, the original Auricaps have been reinserted and will stay, as the system is now hum-free

All the above being said, I'm not quite out of the woods yet. The process of eliminating the hum involved taking the Relay board out of the "loop" and running wires directly to input and output of the Analogue board. In theory, the Relay board shouldn't make any difference, but previous experience (from when I first built the GK-1R) shows that it may not be as straighforward as all that.

However, the main thing is that now I have music again! Those 3-4 weeks without music were scary!

I haven't had time to listen very much to the differences, but I second Steven's opinion that especially the 1 uF Platinum cap is worth the while. Bass certainly seems to dig deeper and have more slam. The Platinums also seem to render details in a most natural manner. I'll listen some more and report back later if I feel there is more to report. I should add that the improvement is worthwhile and quite pleasing.

If anyone runs into hum problems of the sort I've described above, please do not hesitate to contact me. I guess I've tried most of the things that can be done to remedy hum problems in the GK-1R over the last few weeks, poring over the GK-1R for endless hours.

But now there's lovely music, and all is bliss

stvnharr · « **Reply #38 on:** 29 Apr 2007, 11:23 pm »

Jens,
I've been wondering about your Platinums as you've been quiet since receiving them. Now I know.
I don't have a 1R, just a plain GK-1. I've been bugged by hum at times. I've found that it's usually been attributed to solder joints on the source switch. I now run just a single input, and everything is very quiet.
I once had a pair of .47uf Dynamicaps on the output, and had no hum from them. At the final choice I was deciding between 1uf Dynamicap and the Mundorf. A second pair of 1uf Platinums with long leads to the board was too costly for perceived minimal benefit.
I think you find that everything will sound better now that you have music.

Steve

andyr · « **Reply #39 on:** 30 Apr 2007, 11:16 am »

Quote from: stvnharr on 29 Apr 2007, 11:23 pm

Jens,
I've been wondering about your Platinums as you've been quiet since receiving them. Now I know.
I don't have a 1R, just a plain GK-1. I've been bugged by hum at times. I've found that it's usually been attributed to solder joints on the source switch. I now run just a single input, and everything is very quiet.
I once had a pair of .47uf Dynamicaps on the output, and had no hum from them. At the final choice I was deciding between 1uf Dynamicap and the Mundorf. A second pair of 1uf Platinums with long leads to the board was too costly for perceived minimal benefit.
I think you find that everything will sound better now that you have music.

Steve

Mmmm, Steven,

I have a GK-1R and absoloootely no hum! But it's not a "stock" GK-1 ... I changed several caps. I don't have Platinums for the input coupling caps ... so that's certainly something I will try in due course.

Next project, though, is to gain brownie points from the "trouble and strife" by putting 3 boxes worth of stuff (3-way active XO, AKSA modules and associated PSes) into one box. because of the effort involved, this must include upgrading to LFs!!

Regards,

Andy