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Old 29th March 2013, 08:39 AM   #91
andyr is offline andyr  Australia
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Quote:
Originally Posted by Jens A. View Post
Well, I got a bit of a surprise - or perhaps more of an eye opener - last night.

I sat down to listen leisurely to a couple of CDs, but it soon became evident that there would be nothing leisurely about this listening at all!

Chance had it that I had chosen a couple CDs that I hadn't played since before I implemented the GK-2. And I need to mention that these CDs were by no means special audiophile stuff or anything, just some more or less ordinary pop/rock, but also CDs that I have played hundreds of times before and know extremely well.

Therefore, it also came as a revelation to me that they sounded very different - and then again, not. Let me explain: The very different things are the layering, texture, and detail, which are hugely different (= improved) over the GK-1. Especially the layering and detail are so much better than I was used to. Even the tiniest details get to have their place in the sound image, and texture is improved as well, rendering more "air" around instruments, voices etc.
And then, what is not changed is the music (thank you for this!) and musicality (even more foot-tapping than before).

So, what the GK-2 did last night was to take two seemingly "stock" recordings and raise them to a new level. It simply turned out that there were previously unearthed things in these recordings that the GK-2 managed to dig out.

Guys, this is no small feat!

Applause, Hugh, applause!

Cheers,

Jens
Having at last got my GK-2 working (in its loverley new case) and run in, I have to agree with everything you've said, Jens - and couldn't have said it any better myself.

Good as the GK-1 board was (and mine went to a new home - and the buyer is rapt with it), the GK-2 does everything better!

I've been waiting for this day for a very long time but well done, Hugh. Anyone with a GK-1 should make the effort to upgrade. You won't regret you did.


Regards,

Andy

PS: The case comes from a great Italian supplier - http://www.hifi2000.it/. The ebony knobs were made by Duc ('lovetube' on SNA).
Attached Images
File Type: jpg GK-2 Front.jpg (97.6 KB, 253 views)
File Type: jpg GK-2 Inside 1.jpg (606.9 KB, 240 views)

Last edited by andyr; 29th March 2013 at 08:49 AM.
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Old 2nd April 2013, 12:52 AM   #92
LPM is offline LPM  Australia
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That's a very nice enclosure Andy, it rather leaves mine for dead.

I did have every intention of fitting a new case myself as the upgrade clearly provided a perfect opportunity, but in the end I couldn't wait to get the GK2 into my system and I've had no desire since to remove it. You obviously have far more patience than me. My GK1 remains in my parts cupboard for now; it's like thinking about selling an old friend.
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Old 2nd April 2013, 09:41 PM   #93
AKSA is offline AKSA  Australia
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Andy's meticulous approach is commendable, I've seen this GK2 and it's superlative.

Jens too as build a wonderful GK2 in Copenhagen, very well made.

There is a lot of work in a preamplifier, and with all the multiple inputs a lot more than a power amplifier. I take my hat off for the wonderful work lots of GK2 builders have been through!

Cheers,

Hugh
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Old 4th April 2013, 06:43 PM   #94
Jens A. is offline Jens A.  Denmark
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Originally Posted by AKSA View Post
Andy's meticulous approach is commendable, I've seen this GK2 and it's superlative.

Jens too as build a wonderful GK2 in Copenhagen, very well made.

There is a lot of work in a preamplifier, and with all the multiple inputs a lot more than a power amplifier. I take my hat off for the wonderful work lots of GK2 builders have been through!

Cheers,

Hugh
Sure is a nice enclosure, Andy, those Italians do a good job!

My own GK-2, which is an 'R' version (i.e. fully remote controlled, now with a wonderful TKD motorised pot ), is housed in the enclosure I got when I made the GK-1 quite a few years back. It is a pretty solid Monacor enclosure (no longer available, unfortunately), for which I had a 10 mm aluminum front custom made with a black acrylic insert for the buttons and diodes.

I actually rearranged things a bit inside when I installed the GK-2 board to get the trannies even further away from the electronics.

I'll try to remember to take a few photos inside and outside next time I take it out of the system (which will probably be when I implement the mute change to the Relay Board)

Cheers,

Jens
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Old 7th April 2013, 06:00 AM   #95
andyr is offline andyr  Australia
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A late update: am listening to Leonard Cohen's "Book of Longing" on CD (words by LC, music by Philip Glass). Hadn't listened to this with the GK-2 before today ... immediately obvious that the bass goes much deeper! This gives a greater (and delicious! ) weight to the bass end of the frequency scale

Whereas before I would've said that my tricked-out GK-1 was, maybe, 8.5 out of 10 - ie. there are certainly better retail preamps out there ... but they cost 10s of thousands of $$$ - now, my GK-2 is at least 9 out of 10 ... and my GK-1 is back at 7! Now, I would have to spend many more $$$ to better it.

Regards,

Andy
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Old 8th April 2013, 02:29 PM   #96
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Quote:
Originally Posted by andyr View Post
Having at last got my GK-2 working (in its loverley new case) and run in, I have to agree with everything you've said, Jens - and couldn't have said it any better myself.

Good as the GK-1 board was (and mine went to a new home - and the buyer is rapt with it), the GK-2 does everything better!

I've been waiting for this day for a very long time but well done, Hugh. Anyone with a GK-1 should make the effort to upgrade. You won't regret you did.


Regards,

Andy

PS: The case comes from a great Italian supplier - Hi-Fi 2000 contenitori per l'elettronica, case modding HTPC, Galaxy, rack, DIYaudio, computer cases, front panel express, knobs,milled Handles, milled fronts, hi-end,. The ebony knobs were made by Duc ('lovetube' on SNA).

Nice job Andyr But do you really need to have input relays and long connection wires to them? I would preferably put it as close as possible to RCAs and connect it with short silver wires.

P.S.: Are this Clarity caps MR series?
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Old 8th April 2013, 08:37 PM   #97
andyr is offline andyr  Australia
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Originally Posted by supernet View Post
Nice job Andyr But do you really need to have input relays and long connection wires to them? I would preferably put it as close as possible to RCAs and connect it with short silver wires.

P.S.: Are this Clarity caps MR series?
IMO, the NAIS input relays used in the 'R' version provide a better signal contact than the 5-position Lorlin switch Hugh supplies for the 'M' version, due to the fact that the relays have gold-plated contacts enclosed in a sealed Nitrogen atmosphere.

The Relay board is located as close to the back of the case as I wanted to put it - but I'm willing to accept that squeezing it closer might've produced a better sound. However, I get absolutely no mains-induced noise.

Yes, the input caps are Clarity MR. The output caps are RelCap RTX, as that's what I had used in my GK-1.


Regards,

Andy

Last edited by andyr; 8th April 2013 at 08:43 PM.
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Old 8th April 2013, 10:49 PM   #98
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I'd like to clarify a few things in this GK-2 discussion, if I may.
There are simply not very many GK-2's in existence, and there are not going to be many in the near future for sure, as Hugh is just not up to it at this time. I was the beta developer of this unit in 2011, mostly because this was an opportunity that came my way. Hugh and I worked together to get the unit functional and operating. I knew early on that the circuit design of this unit was unique and original and full of audio promise. All that came true.

Much of the discussion that has existed seems to be how the GK-2 relates to the GK-1. Well, all I can say is that the two units are only related to each other by the designer himself but not much in the circuitry, which is where it all happens. The GK-1 is two stage design with each stage having it's own power supply and is capacitor coupled in between the stages. The level control was set in between the stages, an unusual design concept that worked well. It was possible with this two stage design to run a separate output from the first stage for a subwoofer with no downside to anything other than adding additional wiring to the mix. I was amongst those who did this to my GK-1 in the belief that there would be some kind of improved subwoofer sound by bypassing the buffer stage and output cap.

The Gk-2 is entirely different being a single stage design with a single and unique power supply design. The level control is in the conventional position, at the unit input into the circuitry. There is really no provision for a separate subwoofer output like one could do with the GK-1. Although that being said, it is possible to branch an output off the circuit, add a capacitor and grounding resistor and have a separate output, but that is not a feature of the design. For a second output option, it is far easier to just parallel a second output at the end of the circuit, or else branch an output off at the output cap and use a larger output cap for a subwoofer output.

With these things in mind, I recently performed an experiment to compare the 3 outputs possible for a subwoofer output and only played my subwoofer in order to compare. My observations with this are in no way definitive, but merely my own observations within the context of what I did. The music I used was a familar pop disc with lots of good bass, and an sacd of the Saint Saens Organ symphony with lots of good low organ music. I listened only to the subwoofer, a Joe Rasmussen design that I built some years ago that supposedly is flat down to 20hz. I built to Joe's specifications and assume that mine is similar in performance to what he designed.
For the experiment I first played the subwoofer from the standard output as a reference to my ears and then could quickly shift the connection to a second output to hear any differences, and then go back and forth a couple times just to be sure.
The bass guitar and bass drum on the pop disc really stood out and I rather enjoyed listening to just that. I never heard any difference between any of the outputs in doing this. The frequencies are just not low enough to really be affected by the 1uf standard output cap versus a 10uf electro cap, with the much lower cutoff frequency, that I was using for the second output.
I then went to the organ disc, which also contained a Barber and a Poulenc organ piece along with the Saint Saens symphony. The organ in the Barber and Poulenc pieces sounded magnificent with the subwoofer. But again I heard no difference in the 3 outputs.
Lastly I listened to the Saint Saens and where the organ makes it's entry at about midpoint in the first movement. This is where there is some really low frequency organ music, well below the 40hz area of the bass guitar. This is where I thought that if there was to be a difference, I would hear it here. All I can say is that the 3 outputs were the same to me. They were all down in volume level from the slightly higher frequencies of the other organ music and the bass guitar. This is just more reflective of the limits of my subwoofer than anything in the preamp.

Given the current low numbers of GK-2 that are around, much of my post is essentially irrelevant at this time. But should that all change in the future, it all could be much more relevant. And should there be a subwoofer output incorporated into the unit, it will be properly installed and there will be no need for user modification.
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Old 9th April 2013, 08:27 AM   #99
Jens A. is offline Jens A.  Denmark
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Thank you, Steve - this is very good information!

Although - I am surprised there should be so little (or no) difference between the two outputs. Tube output stages are notorious for softening the bass, and since the tube stage is the same as in the GK-1, where there was (IMO at least) a clear difference in bass precision between the tube and the SS output in the bass region, it is somewhat strange that there should be no difference in the GK-2

But then again - as you say - the circuits are very different

I have been planning a similar test to yours, except that I will do the test full range, i.e. without turning off the rest of the frequency range. For me, that will make it easier to pinpoint any differences.

In my current setup this is very easy to do, as it is just a couple of clicks in the computer software controlling the digital Xover units to change the routing to just take the input from the tube stage - I do not even need to fiddle with the plugs (which is a good thing, since my GK-2 is inside a cupboard).

I use my bass system from 16 Hz to 250 Hz, so it is not just a sub. Whether this makes a difference or not remains to be seen ...

Let us see if I come to the same conclusion as you

Cheers,

Jens
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Old 9th April 2013, 08:43 PM   #100
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Originally Posted by Jens A. View Post
Thank you, Steve - this is very good information!

Tube output stages are notorious for softening the bass, and since the tube stage is the same as in the GK-1, ...................But then again - as you say - the circuits are very different

Jens
Jens,
The GK-2 preamp uses a small signal dual triode tube in a cathode follower configuration in a buffer circuit. This is not a power output circuit with a high power tube with associated damping issues in the bass. There is a big difference, and I think you are confusing the two.

Steve
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