[AKSA]

Hi Ron,

I was not aware that Wima had done a low voltage MKS - thank you for letting us know!! Years ago Philips used to do a block MKS in 100V, but until now that was the lowest filmcap voltage I'd seen in the >10uF range.

In truth, a single 22uF should do the trick here.  I used 47uF electros because they are small, but a film cap may be more effective at lower capacitance so give it a try.

Cheers,

Hugh

[stvnharr]

My comments about the tantalum caps need to be taken in the proper context.  The improvement I gained with realizing low single digit jitter and resultant large drop in the sound floor may be much more than any noise reduction gained by the tantalum caps.

[andyr]

I replaced the super e-cap configuration of C4 with a film cap, Solen 47 uF 250V.  It is big measuring 1.5” x 2.1”.  I also replaced a BG at C7 with the same cap.

Hi Philip,

Did you twist the pair of wires to each Solen?  (I believe this reduces pickup of noise?)

Regards,

Andy

[kyrill]

This got my attention upon initial posting.  However film caps at the 2 positions are just not in the cards.  Thus I thought I'd give the tantalum caps a go, the expensive AVX ones no less.
Well, all I can report is that the tantalums really offer not much difference to the previous caps, Rubycon ZA at C4 and Sanyo OsCon at C7. [ ]However, since I was working on the GK-1 I decided to take out the output cap,in my instance a 1uf Mundorf Silver/Oil, and just replace it with a wire link.  The Platinum on the input of the LF should take care of anything, so seemed safe to do this. This seemed to make a small improvement, but not too much really. 

However, if you really want to get serious about noise reduction and an increase in music.................................. ..................
Modify your cd player with a fancy aftermarket clock and power supply.  I recently did this on my Marantz player.  The noise floor dropped towards the center of the earth and all this music emerged with new clarity.  ALL the veils that people so commonly refer to are removed.
Here are some links to research:
www.tentlabs.com
www.newclassD.com
www.audiocom.co.uk
If you can do the work yourself, can be done for as little as a 200USD.  If it's done elsewhere, figure on 500USD and up.

Steve

Hi Steve

I "dared" some time ago to delete caps in the input or output signal between source all the way up to poweramps, having your line of reasoning. However in the case of the GK1 you do something that i do not dare. I hold on to the output cap of the Gk1 and remove the input cap of the power amp.

without outputcap the GK-1 delivers ( if i understand Hugh right) 40V DC, so it introduces relatively high voltages on the IC. If ever the Gk1 this way is connected to another device with removed caps disaster in the amp next to the tweeters are surely to happen.
 normally caps ( unless with tube sources/preamps) removed, pass thru DC between 100mV-2V

[stvnharr]

Hi Steve

I "dared" some time ago to delete caps in the input or output signal between source all the way up to poweramps, having your line of reasoning. However in the case of the GK1 you do something that i do not dare. I hold on to the output cap of the Gk1 and remove the input cap of the power amp.

without outputcap the GK-1 delivers ( if i understand Hugh right) 40V DC, so it introduces relatively high voltages on the IC. If ever the Gk1 this way is connected to another device with removed caps disaster in the amp next to the tweeters are surely to happen.
 normally caps ( unless with tube sources/preamps) removed, pass thru DC between 100mV-2V

I could switch my Platinum caps around a bit, but I can't really be bothered. I don't think anything is going anywhere else for some time.

Steve

[gerado]

OK you guys,
winter is approaching in OZ, which means longer nights and more time over the soldering table 
But trying to follow all the mods which sound so worthwhile is certainly confusing, going back and forward all the emails is giving me vertigo.

For those of us who are daring but do not have the electronic know how, we would be greatly helped by some sort of road map about what to do.

A sort of mod guide with
basic mod
middle mod
advanced mod
and "if you dare mod straight wires and all"  specifying brand ,  type( film etc cap) and value range/size to make sourcing easier.

This would systematically document once and for all the great changes done to this beaut pre amp. It would be time consuming  to compile but a very valuable resource.

The same could be said about the LF mods.

Anyone?

[PT914]

Hi Andy,

I did not twist the lead wire to the Solen caps.  I used 18 gauge teflon coated wire as leads to help support the heavy caps and tried to use the shortest leads as possible.  I have no problem with hum with the addition of the large caps.

When I return from vacation, I will try to determine the relative contribution of C4 and C7 to the improvement.  I first changed C4 on one channel and noticed a huge improvement in the high and when I changed the other channel I changed C4 and both C7 to Solens.  I think the C4 change contributes the majority of the improvement but only with both channel changed did I notice the bass improvement.

Cheers,
Philip

[kyrill]

the value of C4 and C7 are the same same as in the building manual ( except Hugh's suggestion "In truth, a single 22uF should do the trick here.  I used 47uF electros..."?

[stvnharr]

OK you guys,
winter is approaching in OZ, which means longer nights and more time over the soldering table 
But trying to follow all the mods which sound so worthwhile is certainly confusing, going back and forward all the emails is giving me vertigo.

For those of us who are daring but do not have the electronic know how, we would be greatly helped by some sort of road map about what to do.

A sort of mod guide with
basic mod
middle mod
advanced mod
and "if you dare mod straight wires and all"  specifying brand ,  type( film etc cap) and value range/size to make sourcing easier.

This would systematically document once and for all the great changes done to this beaut pre amp. It would be time consuming  to compile but a very valuable resource.

The same could be said about the LF mods.

Anyone?

Geraldo,
All you really need to know and do is:
1. .47uf teflon cap at C1  Most use Sonic Cap Platinum.  Install off the pcb in place of signal input wire.
2. .01uf teflon cap at C19.  Small size and can be interchanged with the stock cap.

3. Tubes: This is pretty subjective to the listener.  I like the NOS 7308's, though they are a little expensive.  Stock tubes are fine.  NOS 6es8's may bring a small improvement.  Again, it's pretty subjective.
 
Anything else that has been described in these pages is extra.  You may hear some benefit, you may not.  I've changed most every cap in the whole GK-1, and only the above 2 provided any clear improvement that was easy to hear.

Steve

[jules]

The C4 & C7 mod, using film caps [I read Hugh's view as suggesting that 22uF is acceptable too kyrill] apparently works to reduce "differential noise".

I'm wondering what the source of this noise is. Is this internal to the amp or are we talking about something produced by the grid power supply? It seems that the power supply in many parts of the world can be a real problem. The US system with its lower voltage seems to be particularly susceptible to contamination, as do buildings with poor wiring.

Philip ... What's your home power supply like and have you done the C1 teflon mod.?

jules

 

[RonR]

The replacement of C4 and C7 seems to be the ideal application for the new WIMA MKS-2XL film caps.

Can someone find a small-quantity supplier?? 

I can only find 1 supplier that has these in stock (10% version), TAW Electronics in the US.

There are not many left, and they're 11 USD each!
Hopefully the price will go down as they become more common.

Also, for those "In the trade", WIMA will send out small quantities as samples.

Cheers,

Ron.

[kyrill]

"there are not many left.."

they sell by single pieces..?

[andyr]

I can only find 1 supplier that has these in stock (10% version), TAW Electronics in the US.

There are not many left, and they're 11 USD each!
Hopefully the price will go down as they become more common.

Cheers,

Ron.

Mmmm, the only problem with buying +/-10% value items is that you probably need to buy at least 10 of them to get a statistically likely chance of getting 2 values within a few % of each other.    (IMO, getting 2 values 10% apart is just too much.)

Regards,

Andy

[kyrill]

it completely depends on the application?

[smilemakr]

OK you guys,
winter is approaching in OZ, which means longer nights and more time over the soldering table 
But trying to follow all the mods which sound so worthwhile is certainly confusing, going back and forward all the emails is giving me vertigo.

For those of us who are daring but do not have the electronic know how, we would be greatly helped by some sort of road map about what to do.

A sort of mod guide with
basic mod
middle mod
advanced mod
and "if you dare mod straight wires and all"  specifying brand ,  type( film etc cap) and value range/size to make sourcing easier.

This would systematically document once and for all the great changes done to this beaut pre amp. It would be time consuming  to compile but a very valuable resource.

The same could be said about the LF mods.

Anyone?

Geraldo,
All you really need to know and do is:
1. .47uf teflon cap at C1  Most use Sonic Cap Platinum.  Install off the pcb in place of signal input wire.
2. .01uf teflon cap at C19.  Small size and can be interchanged with the stock cap.

3. Tubes: This is pretty subjective to the listener.  I like the NOS 7308's, though they are a little expensive.  Stock tubes are fine.  NOS 6es8's may bring a small improvement.  Again, it's pretty subjective.
 
Anything else that has been described in these pages is extra.  You may hear some benefit, you may not.  I've changed most every cap in the whole GK-1, and only the above 2 provided any clear improvement that was easy to hear.

Steve

Steve--

Thanks for your posting summarizing the cap changes.  I recall reading posts (not necessarily yours) from several months ago that changing from the supplied potentiometer to a stepped attenuator (such as the TKD) can yield a noticeable improvement.  I don't recall anyone concluding later that a stepped attenuator is NOT a worthwhile upgrade.  In addition to the recommended cap changes, and maybe some tube rolling, do you think a stepped attenuator is a worthwhile upgrade as well?  If it is, I want to allow room for it in the final layout and chassis I construct, now that I'm getting to that point.

Mark

[gerado]

Steve,

I hope I'm not jumping in here,

apart from the stepped attenuator  which I thought made a noticeable difference(and I only used a 60dollar one), some have also found that if you use both the sub out and  the tubes out, a buffer also makes big difference.  I do not understand the technical reasons for this other than if you use a powered sub its a must.

Andy you know more..

[AKSA]

Hi Theo,

Andy, would you care to add your comments here?  With some qualification, I agree with Theo,

Cheers,

Hugh

[andyr]

Gentlemen,

Yes, with Hugh's assistance, I created an op-amp buffer circuit to go between the wiper of the volume control and the "Sub Out" RCAs, because I needed to be able to drive 35' interconnects (between my GK-1 and active XOs, as I use Sub Out to drive the bass LP section of my active XOs - and I get more bass punch as a result, compared to driving the bass from the normal tube output stage).

However, this buffer circuit turned out to have an unexpected benefit ... it made the bass from the Sub Out go deeper!  aa  BTW, this wasn't revealed on my own system - I had lent my GK-1 to "SuperMart", who was running a sub with his AKSonics, and he just substituted my GK-1 for his Swift.

A "naive" explanation is that, when you connect a sub to the volume wiper, the bass signal from "Sub Out" is somewhat degraded, depending on how far you have the volume turned round.  Putting a buffer here (just as there's a "tube buffer" on the "normal output") means the signal is no longer degraded.  So I recommend it! 

Regards,

Andy

[kyrill]

"degraded"?

I would expect the output impedance is changing in accord with the position of the wiper.

to high an output relative to the input of the sub amp less bass and so on.not only less bass, also less dynamics. that is therefore i like the output impedance to be less than 100 and or the input impedance at least 47k better 100+k

[gerado]

Andy,

when I connect the sub out, the tube out signal is degraded. The tube sound goes flat and looses all the top end. I have a vague recollection that Hugh had a reason for this, I think?  I am not sure if the buffer fixes this issue as well?

Theo