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Gieseler Audio

Power supply upgrade for Gross, Fein & Klein III DAC’s.

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Hi everyone - well I have just made a very interesting discovery regarding the power source for the Gross, Fein & Klein III DAC’s.

Purerly on a whim & at the suggestion from some knowledgeable people I decided to run a Gross DAC from my new M18 Kraftwerk 12v 4A PSU.

What! - as you all know I’ve been telling everyone for years all my DAC’s run on AC not DC so why would I be trying this.

Up untill recently all my DAC’s needed + & - internal voltages & the only way to do this is run them from a AC supply.

With the Gross & the new transformer output design it eliminated the need for negative supplies except for one small negative bias supply for the muting transistors.

Then about ten months ago I changed the muting system to a new photo MOSFET relay setup. NOW all of a sudden the Gross only had positive internal supplies

so the feasibility of runing from a external DC PSU was entirely possible.

But why would I try this? I go to a lot of effort with the internal PSU’s so I’m confident they are very good & I had already tried a much larger external transformer wth no sound change.

As I said before it was purely on a whim & was not expecting any sound quality change

OMG - I was totally gobsmacked at the sound improvement - I thought this can’t be right so I did the comparison another half a dozen times - same result!

Then I tried it the next day & then a few days later - the result was very conclusive that the big external DC PSU was significantly improving the sound.

OK time to see if any one else agrees so I asked a experienced Gross owner & a Fein owner to do the same comparison - conclusion - both agreed on the sound improvement.

Now 12v is not the ideal external dc voltage due to the voltage drop from the DAC’s internal bridge recifiers but it is safe & works very well. My next step is to modify the 12v 4A unit

for 14v output which will be the optimised voltage for all the DAC’s internal PSU to work correctly. While I’m at it I thought I would also try replacing the single main filter cap with 

a bank of 18 Silmic II caps which should improve things even more. However the Silmic caps are about $5 a pop so that option will bump up the price quite a bit.

OK so at this stage I will doing a 14v version of the 12v 4A M18 Kraftwerk PSU especially to just suit the Gross, Fein & Klein III - cost $375 - the same as the current model.

Plus a new pure Silmic II version at $500. I will order the boards tomorrow so about two weeks away.

Guys I’m so confident about this upgrade that all units sold will automatically come with a return for refund in seven days option if not completely satisfied.

IMPORTANT! Please no one try runing their Gross DAC’s on a DC supply untill checking with me first that their unit is compatible. Approximately the first fourteen Gross DAC’s

are unsuitable due the negative internal muting bias supply. It is possible for me to upgrade those units to the new photo mosfet relays so then they would suit the new DC PSU.

I will work out a costing on that soon.

Exciting times!

 

 

 

Edited by Gieseler Audio

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I’ll take one for my Gross, all silmac II version please. My serial No 22. 

 

How are are you going with Femto upgrade? I’d be keen to do that. 

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Hi naggots,

thanks for the vote of confidence -  I will be staggered if you aren’t impressed.

OK  I will check out your serial number model etc at work tomorrow & let you know.

RE Amanero femto upgrade 

 Unfortunately I’ve run into a few snags with that.

 However with the new power supply upgrade I don’t think you would bother wanting to do anything else as it really does sound that good 

Edited by Gieseler Audio

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This is great news Clay. Great to see you are experimenting in this way and continually improving your products. Will PM you re requirements for my unit.

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Hi Clay,

 

very interesting!

Will the 9VAC input of all new DACs now replaced by a 14VDC input?

Thanks

 

Matt

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Hi Matt,

 

no - it does bump the price up so all models will stay the same but the new PSU upgrade will be a permanent option.

A bit like the way Naim does it.

When time permits I will probably do a Uber version of the Gross & Fine that run directly from the big 12v AC 6A transformer.

Edited by Gieseler Audio

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Great news for all the current and new owners. Well done for the Australian Hifi scene. I hope some serious overseas exposure is seen soon. 

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Clay,

how is the procedere then?

When ordering a DAC we can choose either AC or DC input ?

Or have alls DACs both AC and DC inputs?

Thanks

 

Matt

 

 

Edited by matth

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All new Gross, Fien & Klein III's will run on AC or DC 

AC 9v  DC 12v - 15v

Std 5.5m 2.1mm power jack input.

The only exceptions are the special active versions of the Gross & Fein DAC. 

Edited by Gieseler Audio

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For any Gross owners wanting to do a quick check to see if it will suit a DC PSU.

Remove the lid & see if there is a blue power transformer on the board.

If so it is Unsuitable.

However I will be offering a modification service on the early versions to make them suitable for DC operation by changing them over to the photo MOSFET relay system.

A bit of time involved as the pcb has to be fully removed - negative bias parts removed or disabled, transformer disconnected & photo MOSFET retro fitted. I would think $200 would cover it & that would include return freight.

986841742_earlyGrossDAC.JPG.ea1cf22c28bdb8c9d4ebbbefaf06a71f.JPG

 

 

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I tried the 12v 4a power supply yesterday on a Fein dac, and I’ve had a few DACs through the house in the last week or 2, and let me tell you that the Fein with the power supply is a game changer. The DACs I’ve had include the Chord Tt2 and M Scaler combination and the Holo Dac!

 

ill write a review later today but if you are a GroB or a Fein owner order your power supply this morning because there’s going to be a waiting list...

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1 hour ago, Gieseler Audio said:

All new Gross, Fien & Klein III's will run on AC or DC 

AC 9v  DC 12v - 15v

Std 5.5m 2.1mm power jack input.

The only exceptions are the special active versions of the Gross & Fein DAC. 

Hi Clay

 

Is there scope for the Klein II to be converted to use a 12V DC PSU?  

 

Cheers

 

Pete

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Hi Clay,

I’m happy to join the party. Pretty sure mine will be on the early list so will need to be sent in for the full upgrade.

Not that I doubt your DC power supplies - I have had a few and they have been great - but if I have an existing DC12V supply it is fine to use isn’t it?

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 Actually John I think you will be okay.

 Yours did to come back to me for some work and I’m pretty sure I upgraded it to the photo MOSFET relays but anyway I’ll check my records on Monday.

 I have a feeling you’re good to go though.

😀

Edited by Gieseler Audio

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That's great news, Clay!
By all accounts the Gross Dac was already rubbing shoulders with dacs 3x it's price tag.. now there's an external DC PSU "significantly improving the sound"
Game over

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Just a question @Clay. I'm sure the answer will be No but...

 

I've got one of your original Klein dacs AK4490EQ bought Sept 2015 s/no 00040.

I guess this power supply is no good for me?

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custom_made - yes I’m pretty amazed at the difference the big DC PSU makes.

I will definately be keen to recompare the Gross to a couple of DAC’s which it could not quite match before.

Might be a different story now.

Jeddie - Sorry no all the Klein I & II’s will only work on AC.

Edited by Gieseler Audio

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The Gross doesn’t actually draw much current, even playing high rez files it is less than 500 ma so it is a bit baffling 

as to why the original 2A transformer  plus very good internal regulators can be improved upon.

However In comparison the  transformer used in the 12v 4A Kraftwerk PSU is a bit of a beast with a rating of 12v at 6A so the output impedance would be much lower. Also it is fully immersed in potting compound  hense vibration levels would be very low. 

So now we have a situation where DAC is being supplied with a very stable well regulated low ripple DC supply so it is a much easier job for its internal regulators. I know it sounds like total overkill but at the end of the day it is all about the sound & it is very easy to hear the difference. 

 

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@Gieseler Audio

Hi Clay,

would it make sense to place jumpers inside the DACs for bypassing the rectifier diodes when feeding the DACs with DC or as alternative a separate DC input ?

Thanks

 

Matt

Edited by matth

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40 minutes ago, Gieseler Audio said:

The Gross doesn’t actually draw much current, even playing high rez files it is less than 500 ma so it is a bit baffling 

as to why the original 2A transformer  plus very good internal regulators can be improved upon.

However In comparison the  transformer used in the 12v 4A Kraftwerk PSU is a bit of a beast with a rating of 12v at 6A so the output impedance would be much lower. Also it is fully immersed in potting compound  hense vibration levels would be very low. 

So now we have a situation where DAC is being supplied with a very stable well regulated low ripple DC supply so it is a much easier job for its internal regulators. I know it sounds like total overkill but at the end of the day it is all about the sound & it is very easy to hear the difference. 

 

Never ending journey?

It is good to see that we keep making progress.

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Matt - that is a very good point as the internal rectifying diodes are unnecessary when feeding the DAC DC.

However they do provide a psydo form of galvanic isolation between the various sections. What I might try is runing the DAC chip & Amanero board sections directly from the 12v 4A supply but leave the bridge rectifiers in place for the micro processor & display sections. These two sections generate a fair amount of noise so leaving the bridge rectifiers on them helps add a bit of isolation. The plan is to leave the Gross design as it is so it will run from the external transformer & as an upgrade later the DC supply can be added. In the mean time I will test a Gross with the 12v 4A DC PSU built in & with the above diode mods in place.

I have actually already designed a larger board like this so I will have a working version in a few weeks. With the bigger board it also gave me enough room to add independent left, right supplies for the analogue section of the DAC so that should add extra separation. It makes sense for some buying a new Gross + DC PSU to have the option of buying a fully intergrated version instead. How about “Uber” version. The boards I have coming are for the USB only version & if it sounds as good as I expect I will do a 3 - input version. A rough costing estimate is $2750 on the USB only & $3000 on the 3 - input version.

 

Jventer - yes it is exciting finding a new upgrade path like this & the bonus is previous owners can benifit from it as well.

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1 hour ago, Gieseler Audio said:

However they do provide a psydo form of galvanic isolation between the various sections.......The plan is to leave the Gross design as it is so it will run from the external transformer & as an upgrade later the DC supply can be added. 

Thanks Clay,

nice to know that they provide some galvanic isolation.

IMO, it is the best to leave the design as it is. 

So one can start with the AC supply and upgrade later on to the DC supply, a perfect upgrade path.

What do you think, does the Klein III have a similar benefit from the DC supply as the Gross?

 

Matt

Edited by matth

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