Shunt mode on GK-1

cmscott6 · « **on:** 9 Feb 2004, 01:49 am »

Just got around to rewiring my GK-1's volume pot in shunt mode, and oh what a difference! Biggest gain was in the bass: any doubts I might have had about low bass extension on my AKsonics are gone. This is great! Acoustic bass is so smooooth and resonant.

I am curious, though. What resistors have people used for this purpose? Although most of the signal resistors are Rikens in my GK-1, I used a (NOS?) Holco. I keep reading that Vishay or Caddocks are the bomb for this application.

Malcolm Fear · « **Reply #1 on:** 9 Feb 2004, 07:27 pm »

I initially used a Radio Shack (in Australia we have Jaycar) cheapie,with a DACT stepped attenuator. It improved. I then went for a Riken Ohm. Love it.

Jens · « **Reply #2 on:** 10 Feb 2004, 08:28 am »

As I am in the process of building my GK-1R, I am considering whether shunt mode might be beneficial.

Hugh, any thoughts - I have a suspicion that you may have tried this out during development?

Cheers,

AKSA · « **Reply #3 on:** 10 Feb 2004, 10:34 am »

Jens,

Yes, I have tried shunt wiring the volume control. It does work well, no doubt, but it costs gain, progressive 'feel', and noise. For the GK-1R, with the Panasonic pot, there is very little advantage in my opinion. It's only one man's opinion, however; so I should repeat the DIY mantra, YMMV!

The loss of gain and 'feel' is an issue. With Darl's exhaustive 'wireman' input, I designed the GK1 physically and electrically with many difficult choices throughout the development. Most products are a morass of considered, measured choices, and essentially the whole process is the management of compromise. I made choices for convenience, performance, gain, 'feel', ease of assembly. You can move these parameters around, certainly, but then others rear their ugly heads. It's normal to design for the lesser of many evils. More of this tends to mean less of that, and on balance, I think my choice of a conventional level control connection was right for the majority of audiophiles. I paid very careful attention to the position of the attenuator in the topology, and in this regard, the GK1 is almost unique. I'm not criticizing Chris's choices indirectly here either, but if you change the design in any detail, including resistor and capacitor choices, then it's no longer the same GK1 Darl and I signed off on, and I'm then reluctant to take responsibility for the performance. The problem is that any changes, however slight, to the configuration and choice of components will change the sound. This product is so finely tuned this is just a simple fact; it may sound better, it may sound worse, but it will always sound different. One cap, or even one resistor, will make a difference, and the effect might be pretty big.

Unfortunately, I don't really have the time just at present to give a long explanation/justification on these issues, as my family is arriving home from Indonesia tomorrow morning and I'm flat out cleaning the house!!

I've just finished sanding and varnishing a small landing and three steps, and yesterday I took a large trailer stacked to 5 feet high with garden waste to the tip! Pity me, all you AKSAphiles out there, doing domestic things I hate to do!! I've even cleaned the gutters!

BTW, the Ford is now up and running with its new camshaft/chain, retuned to 9 degrees BTDC, and I have to say it's a different car. Much smoother, more powerful and yet more economical. I'm delighted, worth the effort.

Back to that DAKSA printed circuit design...

Cheers,

Hugh

cmscott6 · « **Reply #4 on:** 10 Feb 2004, 11:43 pm »

I should clarify that I have the GK -1M and, therefore, a different pot than the Panasonic. It is also a pretty easy mod to reverse, depending on your case design...

AKSA · « **Reply #5 on:** 11 Feb 2004, 02:09 am »

Chris,

Thank you for clarifying it. Absolutely no criticism of you intended, and I hope you took no offense.

The cermet does indeed benefit from shunt operation; the Panasonic does not.

Cheers,

Hugh

Jens · « **Reply #6 on:** 11 Feb 2004, 11:35 am »

Hi Hugh,

Thank you very much for your elucidating explanation about the GK-1 development.

Also, the point that there is a difference between the cermet and the Panasonic may explain why GK-1 owners have had different experiences with the shunt mode.

Sounds as if you've been busy housecleaning. Hope you got everything in order before the family got back

Cheers,

cmscott6 · « **Reply #7 on:** 11 Feb 2004, 02:31 pm »

Hugh,

No offense taken; I should have been clearer. Hope all is well!

BTW I just finished a Hagerman Cornet tube phono pre. Sounds very, very nice through the GK-1.

Take care!

Chris

Malcolm Fear · « **Reply #8 on:** 11 Feb 2004, 07:17 pm »

I thought you couldn't use shunt mode with the Panasonic, because the earth is common inside the Panasonic. You have to wire the pot arse about, so you would end up with a mono signal coming out?

AKSA · « **Reply #9 on:** 11 Feb 2004, 09:01 pm »

Hi Mal,

Yes, thanks for pointing it out, you are quite right; I realized minutes after writing the post that this was an issue. My apologies! The earths are conjoined, and that scotches using shunt mode anyway.

I have to say that the Panasonic is the best conventional conductive plastic pot I've ever heard.....

Cheers,

Hugh

Malcolm Fear · « **Reply #10 on:** 12 Feb 2004, 10:09 am »

Hi Hugh
I don't understand cars.
>>BTW, the Ford is now up and running with its new camshaft/chain, retuned to 9 degrees BTDC
Is this standard Ford tuning?

AKSA · « **Reply #11 on:** 12 Feb 2004, 12:06 pm »

Mal,

No, standard is 6 degrees BTDC. LP Gas powered cars require more initial advance since octane rating is much higher - around 110 RON - and flame propagation is slower at part throttle. But at higher engine speeds, less advance is required, so with petrol advance curves a compromise is needed. You really have to try it out on a variety of settings.

But it runs more smoothly than ever before. Sorry about the thread jacking!

Cheers,

Hugh

DSK · « **Reply #12 on:** 12 Feb 2004, 10:07 pm »

Hugh said "Much smoother, more powerful and yet more economical. I'm delighted, worth the effort."

Yes, yes, be that as it may ....what everyone here wants to know is ....How does it SOUND?

AKSA · « **Reply #13 on:** 13 Feb 2004, 12:31 am »

Hmmm. Well, here are the benefits:

1. Noise floor reduced, particularly at low levels.
2. Great power bandwidth; 3dB down occurs at around 4,200, rather than 3,600.
3. Presentation is more seamless; less peakiness in the system.
4. Transient response greatly improved, particularly in midrange.
5. More satisfying tonal structure, quite evident in late night driving.
6. With bias now optimized, runs much cooler at high levels.
7. Far superior coupling to the floor; driver response seems punchier.

I do hope this answers your question! Now, d'ya see, all technologies abide by the same rules!

Ben can confirm these improvements, witnessed one evening returning from some heavy Bistromathics, where we do our best work. The Nirvana is so far ahead of the stocker, it's a no-brainer.

It's always nice to know you can improve on a big corporation, in this case Henry himself......

Cheers,

Hugh