[MattCassidy]

Yes it as dumb as it sounds . But to be perfectly honest I am not really sure, obviously the source switching is one thing but what about the main board on the GK-1?

I have made my power amp (Thanks Hugh!). I am embarking on the GK-1 next. In the meantime I was considering using a potentiometer to control my volume, then it occured to me a afairly obvius question, why is this not better than a pre-amp as it must have less effect on the signal?

Laymen's terms would be great!

Many thanks, my education continues with the help of you fine people.

Matt

[randytsuch]

Check out this post
http://www.audiocircle.com/index.php?topic=10389

Using just a pot is basically a very simple passive preamp.

For better results, with just a little more work, you can run the signal through a resistor, and then have a pot to ground after the resistor.

Randy

[CButterworth]

Matt,

Currently, I am using a passive preamp, which I built myself.  My intention was to:

1. switch between different sources
2. add a volume control

To switch between sources, I used an Elma switch which is good quality.  Doing this was fairly straightforward.

The volume control was a little more tricky.  Initially, I wired an ALPS 50K pot in the signal path and I managed to get volume control - it worked.

After later discussions with AKSAphile Malcom Fear, I decided to change the configuration of the volume pot.  I placed a 33K resistor in the signal path to attenuate the signal, then used the volume pot between signal and ground.  This is what Randy has suggested.  In essence, the pot was now wired backwards ie. the greater the resistance, the higher the volume because the pot prevents signal from flowing to ground, meaning that more flows to the amp (excuse my layman terminology - I'm a botanist not electrical engineer   ).

The difference.  Well, it was remarkable and obvious.  The bass became more robust, present and solid - not boomy.  Anyway, I since upgraded my speaker to Polk RT600i which a number of reviewers have mentioned a relatively weak bass.  Not in my system, I cannot imagine wanting to add any more bass than I currently get.  Part of this is due to pot wiring.

Incidentally, I made a little soldered breadboard for the signal resistors which uses high quality sockets. This means that I can change the resistor, and hence the attenuation.  Using the 50K pot is not ideal, as I wanted to keep the resistor values relatively low (less than 50K), with the 50K pot, comfortable listening volumes are achieved with the pot turned to around 10 O'Clock.  I'd prefer normal listening volumes to be at around 1 O'Clock.  In the future, I'll hunt out a 20K Alps and use that.  Also at present, I am using Vishay resistors, but could replace them with Rikens.

Regards,
Charlie

[stvnharr]

Charlie,
Why don't you just get an attenuator kit from Michael Percy and forget the pots.  A series kit doesn't cost a fortune.   If you want the best, get a ladder kit, but that can cost a bit.
If you want to go the "purist" route, either a ladder or shunt, with just a single resistor in the signal and ground path is the way to go.
Also, it doesn't matter where the "volume" knob is, you are attenuating the signal level only.

[SamL]

The Elma Ladder Atteunater Group buy on Head-Fi mention by Greg Erskine a few post below is good value and worth a look and you can build something better than DACT without spending a lot more. Got to act quick if you are keen.

http://www.audiocircle.com/index.php?topic=11635

[CButterworth]

Stvnharr,

Thanks fpr the suggestion.  I have found a number of suppliers for stepped attenuators.  They aren't cheap, but I am sure that they'll make an improvement.  With my current set-up I have attenuation is done through a single resistor per channel.

One of these days, I will buy a stepped attenuator, although I am thinking that a TLP may be the next item to dramatically imrpove my system!

Thanks for the advice
Charlie

[Lost81]

Stvnharr,

Thanks fpr the suggestion.  I have found a number of suppliers for stepped attenuators.  They aren't cheap, but I am sure that they'll make an improvement.  With my current set-up I have attenuation is done through a single resistor per channel.

One of these days, I will buy a stepped attenuator, although I am thinking that a TLP may be the next item to dramatically imrpove my system!

Thanks for the advice
Charlie

Oh, you will love the TLP...
Better yet, a TLP Nirvana!
The Nirvana upgrade adds the speed and slam of SS pre-amps to the TLP.
After that, almost every non-tube pre-amplifier I've heard sounds lifeless to my ears.

I can only imagine what a GK-1 sounds like...  


Cheers,
-Lost81

[Lost81]

A friend pitted his pre-amplifier against my TLP Nirvana, and it beat the TLP Nirvana only by a small margin:
it had more "air" in its presentation.

Not bad if you consider how much his pre-amplifier costs (used or new).

Some pics of the pre-amplifier (No, I don't know this person. This link is for illustration only.)

I'm waiting for the opportunity to build a GK-1 with the TKD attenuator, break them in, and organize a re-match



Cheers,
-Lost81

[kyrill]

Hugh or Tinker how much is the minimum the GK-1 can have as an input?

Is it possible to bypass altogether the analogue stage output from a DAC (the DEQX uses the:"we use the Analog Devices AD1853 DACs. These were chosen because they have extremely good internal jitter immunity. We absolutely agree with your experience about the importance of low jitter, and even external jitter correction can be influenced to some degree on the way to a DAC, so DACs that are inherently immune to jitter are the best solution. ) in my case and feed the mini levels of voltages into 3 GK-1?
Would it equal a MC phono cartridge or a MM element (minus the riaa EQ) ?
Would that be possible?

[AKSA]

Kyrill,

This is indeed interesting........

The phono section on the GK1 goes down to MM levels, though it is of course RIAA equalized.  The RIAA EQ can be removed, making it flat, and conferring the necessary sensitivity to run directly from a low voltage output from a DAC using resistor I/V conversion.

Now, there are two types of DAC output.  The first and most common is delta-sigma, which is simply a balanced output, centred at one half the Vcc of digital chips (at 2.5V), and this has lowish output impedance which is actually suitable for driving directly the SS input stage, slightly gain modified, on the GK1.  The second type is the 1702/4 I/V mode, which is current output.  There are very good arguments in favor of this mode over delta sigma since current output has no voltage limitations imposed by the low 5V supply.  A delta-sigma chip normally has a high voltage output which extends to almost 80% of the rail voltage and thus is prone to amplitude compression and other symmetrical (read odd-order) voltage distortions.

Either/or could be used;  the current conversion chips, and there aren't many now, can be fed to a smallish resistor, typically 50R or so, but the voltage generated across this resistor must be less than 100mV pp to preserve linearity.  To achieve an output of 2Vpp, this mandates a gain of at least 20, or 26dB.  The smaller we make this resistor, the lower the distortion, but the more the amplification required, and more amplification means more noise.  The old story - nothing for nothing.......

This is a rather scatty tour of DAC output modes, but I would stress that to verify the effectiveness of your suggestion extensive R&D would be needed.  But my gut feeling is that it's all feasible.

Cheers,

Hugh

[kyrill]

Thanks Hugh
Wonder why you did not start yr life by becoming an electronic engineer
I am happy you didn't. I could not have afford your gear

On another mode, my gut feeling would tell me
this special DAKSA for GK-1 (ugly name by the way, why not P(re) AKSA?
Then we would speak of the "DAKSA-PAKSA-AKSA"combi  
The DAKSA only for dedicated PAKSA owners would be
1) simpler, no analogue opamps and coupled configurations with joined complexities and problems
2) less expensive, but most importantly
3) MUCH better sounding when the analogue amplification is delegated to the PAKSA

So this is the way I will go.
Very, very exciting..
There is no opamp i expect to do better than the gK-1
journey never stops  

(By the way PAKSA is copyrighted