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Gieseler Audio

KLEIN PREAMPLIFIER

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Hi everyone,

Well finally I am about to release the new Klein Preamplifier. The first batch of boards will be arriving next week. The physical design/layout is finalised but there will still be a bit of work left on the software programming side of things. It is a basic unit & designed to go with the Klein DAC. Three pairs of analogue inputs, remote control of input selection, volume & muting. It is using the same case & external transformer that the Klein DAC uses. Output is unbalanced, ten ohms impedance & with a max level of eight volts RMS. The volume control of a preamp is a critical area & for this I have selected the Muses 72320 analogue antenuator chip from the New Japan Radio Company. The feedback on this chip is excellent & it was the choice of Pass Labs in their flagship XP-30 Preamplifier. There will be a motorised volume control on the front panel with a physical knob. This will control the the antenuator chip for maximum sound quality. Power supplies have a major effect on sound quality & after a lot of R&D I settled on a new shunt regulator design of my own. The output section is using a diamond buffer class A buffer composite stage.

Price is $750 delivered Australia wide.I will post some photos next week when I have a populated board & some front/rear panels finished.

Edited by Gieseler Audio

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matth   

I will post some photos next week when I have a populated board & some front/rear panels finished.

 

I like very much the black front / rear panels. :P

 

KR Matt

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bhobba   

Hi Clay

 

I like to keep a pre on hand even though the amp I will be using (an upgraded Prima) has its own volume control.

 

At the moment I am using my Truth pre.  Will pop down to your shop next week with my Truth to see how it goes against it in your shop.  Good chance I could get one.  See you next week.

 

Thanks

Bill 

Edited by bhobba

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Hi Clay

 

I like to keep a pre on hand even though the amp I will be using (an upgraded Prima) has its own volume control.

 

At the moment I am using my Truth pre.  Will pop down to your shop next week with my Truth to see how it goes against it in your shop.  Good chance I could get one.  See you next week.

 

Thanks

Bill

I'm banking that Klein pre with the Muses volume control will smoke your Truth..........:D. :P

Can't wait for your impression @@bhobba, good to see you posting again.....

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bhobba   

I'm banking that Klein pre with the Muses volume control will smoke your Truth.......... :D. :P

Can't wait for your impression @@bhobba, good to see you posting again.....

 

Clay's gear generally has good resale value so I don't really mind buying stuff from him to check out.  If it doesn't take out the truth I doubt I will loose much - but like you I don't think that's likely - but we will see.

 

Thanks

Bill

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Hi Bill,

Good to hear from you. The boards should arrive on Monday so I will get one built ASAP. The Klein DAC drives power amps direct very well but a lot of people feel more comfortable with a hardware volume control in between. To get bit perfect out of Daphile you need to go to fixed out as well so bypassing the soft level control might pick the sound up a bit.

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Assuming this is just a pre-amp and doesn't have a dac in it already, can I connect this to any DAC I have and from the pre-amp, any active speakers I have?

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Jventer   

Assuming this is just a pre-amp and doesn't have a dac in it already, can I connect this to any DAC I have and from the pre-amp, any active speakers I have?

Should be able to.

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Yes Jventer is correct. It is a stand alone preamp so will work fine with standard analogue line inputs & be capable of driving power amplifiers or active speakers.

I'm still finalising the firmware so that is holding things up at the moment. 

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post-112957-0-03244200-1442555367_thumb.Update - I finally have a prototype board up & running, almost!

Programming is definitely not one of my skills so that has been the hold up with the pre-amplifier. I'm using a very high quality Muses 72320 chip to control volume but it needs SPI code from a micro-controller to work.

NJR from Japan kindly sent me a test board with control software which has been a big help. My son & I spent a four hours the other night & he finally managed to gain control of the chip with our own code, needless to say at this point I immediately tore the head off a Peperoni & downed it. I would have had one earlier but was not allowed. Anyway it just needs a little more tidying up of the code & it should be good to go. Notice the nice short signal path, RCA to high quality relays, into the Muses & then into the output stage. The Muses 72320 is a analogue potentiometer but with digital control.

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Great work Clay. The remote will keep people happy and as usual, your tech skills I know will shine, So all in all, for $750, a real bargain

Edited by Bill125812

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The HT bypass is a brilliant idea which I will include in the next model up in the preamplifier range. This is the entry level model & I simply don't have the room on that board for the extra sockets. The next model up will have dual outputs, HT bypass, display screen & no physical volume knob. The display will show the volume level & input selection, I may even get rid of the on/off switch & make that remote too - that will make Johannes happy!

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Jventer   

The HT bypass is a brilliant idea which I will include in the next model up in the preamplifier range. This is the entry level model & I simply don't have the room on that board for the extra sockets. The next model up will have dual outputs, HT bypass, display screen & no physical volume knob. The display will show the volume level & input selection, I may even get rid of the on/off switch & make that remote too - that will make Johannes happy!

Dont mind me  :)

Actually if one wishes to acquire for a desktop system the switch is quite good and then you don't need a remote either.

I see a lot of potential here - various models with various outputs etc.

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lemnoc   

attachicon.gifIMG_1768 (Medium).JPGUpdate - I finally have a prototype board up & running, almost!

Programming is definitely not one of my skills so that has been the hold up with the pre-amplifier. I'm using a very high quality Muses 72320 chip to control volume but it needs SPI code from a micro-controller to work.

NJR from Japan kindly sent me a test board with control software which has been a big help. My son & I spent a four hours the other night & he finally managed to gain control of the chip with our own code, needless to say at this point I immediately tore the head off a Peperoni & downed it. I would have had one earlier but was not allowed. Anyway it just needs a little more tidying up of the code & it should be good to go. Notice the nice short signal path, RCA to high quality relays, into the Muses & then into the output stage. The Muses 72320 is a analogue potentiometer but with digital control.

 

Why do you use a motorised volume control if you use a digitally controlled volume chip ?

 

cheers

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Hi lemnoc,

good question. Being my entry level preamp I wanted to keep a simple functional feel to it so that's the idea of a knob on the front panel. I think quite a few people still like that basic form of control & the motorised pot gives it remote  as well. Click the mute on the remote & knob winds back to zero, click it again & you are back to where you were. I could have used a rotary encoder but to me they always feel a bit weird for volume control. Up down buttons, no way. None of the motorised potentiometers sound particularly good so I certainly did not want to run the audio through one. So summing up, high quality accurate level control but with an old school knob on the front.

Edited by Gieseler Audio

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lemnoc   

Hi lemnoc,

good question. Being my entry level preamp I wanted to keep a simple functional feel to it so that's the idea of a knob on the front panel. I think quite a few people still like that basic form of control & the motorised pot gives it remote  as well. Click the mute on the remote & knob winds back to zero, click it again & you are back to where you were. I could have used a rotary encoder but to me they always feel a bit weird for volume control. Up down buttons, no way. None of the motorised potentiometers sound particularly good so I certainly did not want to run the audio through one. So summing up, high quality accurate level control but with an old school knob on the front.

 

So the pot is not actually being used at all or are there other signals used to drive the volume chip ?

 

cheers

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