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2020 StereoCoffee LDR passive preamp redesign.

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The first StereoCoffee boards I bought provided a very punchy sound but I also had LightSpeed and CloneNote and told Chris Daly that I preferred the CloneNote. About one month later another board arrived at my door with an invitation to try it out. I was able to A/B compare it to the others. Yes, it was a very noticeable improvement over the competition and has been improving since then but the 2020 version has reached a performance level I didn't think possible from any preamp.

 

Electronic ‘experts’ on multiple audio forums including this one, have been known to humiliate Chris Daly over his ever changing designs because he isn’t afraid to go beyond accepted theories and keeps experimenting with great success.

 

Critics  said it couldn't be done, but he did it anyway. I'm sure I would have given up.

 

Chris develops his StereoCoffee boards primarily for own enjoyment of music and I am very lucky to be able to enjoy the efforts of his constant experimentation as are many others. Owners already appreciate this.

 

Over the last two years I have followed StereoCoffee progress to the point where the music I am enjoying is so pure that descriptions like transparent, detailed, etc seem to have no relevance. This isn’t just a flat plane of recorded sound. The experience is more like being enveloped by reality not recordings.

 

NOTE: Only the power/control boards have been updated not the LDR boards.

 

I am obviously completely out of my depth trying to describe the sound I am enjoying from my system but here goes.

 

The sound is a rainforest like ATMOSPHERE... not a rainforest recording. Visualise a black night sky with a myriad of twinkling stars you can hear, total silence, occasional interludes of buzzing insects in the distance, harmonious bird sounds above a trickling brook. Distant human voices reverberating through trees and a frightening thunder crack that whacks you in the chest and a sudden downpour of tropical rain. Phew!

 

That's what I love.

 

It is worth remembering that the 2020 power/control board now utilises triacs and thyristors and performance improves into a perfectly balanced state after about 40 minutes of playing music, not just through it being powered up. It is uncanny how the sound improvement during warmup creeps up without you noticing, until you realise something very special has happened and everything just seems to have expanded as though any audio compression had been removed.

 

BUT, I also realise music from my ESL speakers don't punch out my Pink Floyd albums like my OTL 8 valve Son of Beast amp through VAF DC-X speakers that I have sadly sold. That was an off the planet experience too. My Holton with the StereoCoffee was also impressive with Pink Floyd and the VAFs.

 

Some systems suit vinyl others don't but the music I am experiencing has re-programmed my brain and I am in absolute awe of the beauty within music.

 

I paid $250 for my 2020 3 x input two board kit. Fully built units in a case are also available. Is it worth the upgrade.? YES.

 

My system: Integrated StereoCoffee/bi-amped 2xHYPEX NC122 nCores with internal Xlinks active crossover and 225hZ module. Freestanding Hybrid RM Audio 505 Mini ESL with Satori 6.5 inch mid/woofers in SB Acoustics ARA enclosure kits with tweeter blanked off.

 

Many thanks to all the DIY manufacturers in Australia, NZ and elsewhere. 

 

Cheers, Rob

 

new-board.jpg.0ad01e27fc5f81b2070828b10138387c.jpg

The ALL NEW 2020 StereoCoffee power/control board

 

amp-complete400.jpg.bce611dfac7c933941486c3e041bfb86.jpg

Left middle boards are 2019 StereoCoffee LDR board and 2020 power/control board.

Top and bottom boards on left are Xkitz active crossovers with 225hZ xover modules.

 

system2020x600.jpg.b3e15ec6b0a8dac462a5b579236e25a4.jpg

 

 

 

Edited by robmid
Added info

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Nice report/review on the latest Stereo Coffee LDR preamp Rob, you express yourself well and good to see the passion.:thumb:

 

In considering that the LDR approach is potentially one of the better ways to attenuate an audio signal, and if attenuation (cleanly) is the major goal here - what happens to your system Rob, when you remove the Stereo Coffee altogether. That is, when you try the CD player direct for example?

 

If like me when you do this and find that the soundstage flattens and the involvement in the music collapses, then  you have to assume that the Stereo Coffee is adding something good, or that the digital attenuation in all CD players is somehow flawed? We need to get to the bottom of this in order to answer why a good preamp is needed at all, to keep signal integrity.

 

I really want to take a sip (hear) one of these Stereo Coffees now. I am going to have to build one soon or can I twist your arm to send it over to me for an audition, Rob?

 

Cheers,

 

Steve.

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Hi Steve.

 

When I compared an Apollo CD directly into a Son of Beast valve amp and a Holton the sound was very ordinary so I haven't tried the same test with the StereoCoffee as I am sure I know what the result will be.

 

I am installing a 2020 board on my spare free standing version at the moment so I will PM you when it is ready to audition.

 

Cheers, Rob

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8 minutes ago, robmid said:

I am installing a 2020 board on my spare free standing version at the moment so I will PM you when it is ready to audition.


Thanks Rob, I will pay for postage both ways when the time comes.

 

 

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Hi Rob, 

Great review. I am waiting for my new power board that Chris posted last Friday. Hope I will receive it tomorrow. If so looking forward for to have a late night on Saturday. 

Cheers,

Tom

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On 05/02/2020 at 9:58 PM, Steve M said:

In considering that the LDR approach is potentially one of the better ways to attenuate an audio signal, and if attenuation (cleanly) is the major goal here - what happens to your system Rob, when you remove the Stereo Coffee altogether. That is, when you try the CD player direct for example?

 

If like me when you do this and find that the soundstage flattens and the involvement in the music collapses, then  you have to assume that the Stereo Coffee is adding something good, or that the digital attenuation in all CD players is somehow flawed? We need to get to the bottom of this in order to answer why a good preamp is needed at all, to keep signal integrity

Hi Steve, 

I thought ( maybe mistakenly) that the StereoCoffee LDR neither added nor detracted anything from the source, and that is what we are all really after from a pre-amp -  am I wrong ???

Peter

Edited by pcourtney

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That’s a valid question Peter and I guess what I am posturing is that no one on this forum or on any other fora that I frequent, has adequately explained why a good preamplifier lifts the performance of almost all systems. All of the worlds best systems are fronted by a good preamplifier, with users universally commenting that without the preamp the music sounds a bit lifeless and less real to them. This has also been my experience. I am keen to hear if the Stereo Coffee LDR attenuator hangs on to the dimensionality and low level dynamics like a good active preamp does.

 

Steve

 

 

.

Edited by Steve M

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The late Colin Whatmough ( one of Australia's great speaker builders) stated at an audio meeting he was running some years ago that if you want to get the true dynamics of the music you need an active pre amp.  At the time he was using a slim valve based pre amp made in Australia but I can't remember the brand,  I can certainly detect an increase in dynamics when changing from a passive (no gain) to an active pre amp.  Cheers - M.

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6 hours ago, Steve M said:

I guess what I am posturing is that no one on this forum or on any other fora that I frequent, has adequately explained why a good preamplifier lifts the performance of almost all systems.

Gain matching?

Certainly much more prosaic than most other audio forum explanations, but probably plays a big part in it

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5 minutes ago, mrbugeyes said:

I can certainly detect an increase in dynamics when changing from a passive (no gain) to an active pre amp. 

Yes, my experience also, brings piano to life......

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Also, an active pre amp is a better match to a power amp that has low input sensitivity.  Cheers again - M

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Hi Rob. Good to hear you have the 2020 contol board up and running. I'm still using the 2019 control board and remote control and am very pleased with the results. I've also tried the Mirus pro dac directly into the OAD power amp and as already stated by others, the sound is slightly less dynamic in that the front to back soundstage seems to flatten out. I haven't yet tried extensive A/B-ing it with the OAD pre but may do when I also upgrade to the 2020 boards. I've also been on board with Chris since I tried his early single input jobbie and had the Lightspeed at the same time a few moons ago now. Great to see his total commitment to every nuance of improvement he can wring out of this attenuation method.

Edited by PicoWattson

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On 10/02/2020 at 11:29 PM, PicoWattson said:

Hi Rob. Good to hear you have the 2020 contol board up and running. I'm still using the 2019 control board and remote control and am very pleased with the results. I've also tried the Mirus pro dac directly into the OAD power amp and as already stated by others, the sound is slightly less dynamic in that the front to back soundstage seems to flatten out. I haven't yet tried extensive A/B-ing it with the OAD pre but may do when I also upgrade to the 2020 boards. I've also been on board with Chris since I tried his early single input jobbie and had the Lightspeed at the same time a few moons ago now. Great to see his total commitment to every nuance of improvement he can ring out of this attenuation method.

Hi Pico.

 

Many of the components have totally changed on the 2020 board as far as I can see.

 

I didn't think the 2019 board could be improved and I was astounded when I put on the first track with it installed. Dynamics had changed entirely and holographic imaging was very active, not in a gimmicky way but in a lifelike way.

 

The really interesting thing is the unique LDR current management system Chris has developed improved performances after 40 to 50 minutes to a point where everything seemed more coherent or more lifelike. As though the blank spaces had been filled in.

 

For example, piano now had harmonics on individual strings and voices are full of texture. Bass has much more authority and bass detail is improved too. Live performances have that level of authenticity where you might hear the singer move away from the mike or turn their head for a moment or an instrument get bumped. I have heard detail like this before but never in a way where I feel overwhelmed by the whole experience of being on the stage surrounded by the audience.

 

I think the 2020 might be the final.

 

Cheers,

Rob

 

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On 10/02/2020 at 2:42 PM, Steve M said:

That’s a valid question Peter and I guess what I am posturing is that no one on this forum or on any other fora that I frequent, has adequately explained why a good preamplifier lifts the performance of almost all systems. All of the worlds best systems are fronted by a good preamplifier, with users universally commenting that without the preamp the music sounds a bit lifeless and less real to them. This has also been my experience. I am keen to hear if the Stereo Coffee LDR attenuator hangs on to the dimensionality and low level dynamics like a good active preamp does.

 

Steve

 

 

.

Hi Steve.

 

Chris has kindly built a new 2020 power/control board to replace the 2019 board in my loaner preamp and air expressed it to me. I'll get it off tomorrow after I have packed it and checked postage sizes and weights for you.

 

I just put it through its hoops and I'm sure you will be surprised how brilliantly a well designed passive preamp can perform.  It sounds exactly like mine now, so I am happy to send it to you now.

 

If you are like me you will find low level dynamics and background ambience you hand never heard before positioned accurately on the sound stage.

 

Cheers,

Rob

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Sounds good Rob, I will message you soon.  Cheers, Steve.

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Hi Rob,

just had an email from Chris and we are going to do a 'quid quo pro' so I should soon have a 2020 board. When I paired the early 2019 S/C with a modded Dark Voice, Beyer cans, Kenwood KD990 with an AT33EV cartridge the first vinyl I played was the 2014 copy of Joni's Hejira.

 

Part of the magic was the quasi OTL D/V for sure and the silent Kenwood. The 33EV is such a brilliant all-round cartridge and played through a Talk Electronics MC3. The S/C allowed all these components to really come alive as a whole musical experience. Joni wrote this whole LP as a result of a 'road trip' from New York all the way across country to LA. Her voice - well it was like she was singing right in front of me and she was 3-dimensional through virtually the whole LP was that shaman, Pastorious, appearing/disappearing, weaving a mystical sound. Listening, I was right back then in that decade of so much bloody fantastic music, so intense - deja vu in reverse. I have no doubt that Rob has said it like it is. 

 

I have 2 Bada amps, a h/amp and a power amp, both have to be rebuilt. Both amps have the same preamp set-up of 3 6SN7 tubes - a driver and 2 o/put tubes. I was lucky to get the nod on the Tung Sol round plate 6F8G before they became super expensive. I also bought but not so cheaply the Russian mil. spec 1578 (6SN7). Well using the Tung Sol as driver and the 1578 as o/put tubes, that was it for me - an endgame.

 

The only tubes I want in a system now are these 3 in combo. I wish I had the experience to design a preamp using these tubes with the S/C as volume control. Genuine mosfets, I have the real deal Toshibas as o/put - game over.

 

I have a Parasound, a Hypex and a push/pull Kat88 power amp - I want to hear the 2020 S/C with these and my Heybrook Sextet Mk 1V  speakers with externalised x/overs recapped and rewired - lock the door, bong ready - Joni/King Crimson/the Floyd/Pure Prairie League - time travelling back to the 70s.

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Another reflection - good to see designers having a genuine "continuous improvement" philosophy, and one that allows earlier designs to be upgraded.  I hope more in the industry take this cue!

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I have taken delivery of Chris's latest iteration.


Pics to follow. 

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It’s still on my list as a project, so keep the updated info coming!

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This is a review of the sound of the Feb2020 version of the ‘Stereo Coffee’ passive pre-amp.

I first listened to the ‘Eurythmics: Ultimate Collection’ which is very well recorded with a big almost electronica type sound on some, but not all tracks. Annie Lennox’s vocals feature prominently on most tracks. Already very strong the latest Stereo Coffee is a surprisingly big improvement on the excellent 2019 version.

The improvement is that the mid-range, especially the vocals, are more  prominent in a good way i.e. the human voice bounces out from the backing instruments. And the vocals sound like I assume that they sounded when they were recorded in the studio.

But this also applies to the backing instruments because they are ALSO more prominent and more like I assume they sounded in the recording studio! 

I would describe the sound overall as:

1. Greater separation between the vocals and individual instruments, and between the individual instruments themselves.
2. Greater realism of the voices and instruments which gives a very 'clean' sound.
3. A very 'dynamic' sound i.e. the vocals and the instruments are very dynamic.


Next I listened to a jazz album by Patricia Barber called ‘Modern Cool’ and it was simply superb on the Feb2020 Stereo Coffee and the Amp Camp Amp V1.6 Class A power amp. What a combination!

It was like being in a small jazz venue it’s so realistic.

The quietness around voices and instruments is uncanny - I could actually hear the clock ticking in the next room in quiet passages!

 

Next I listened to Sydney band Cruel Sea's 'Three Legged Dog' CD released in 1995. And it sounded absolutely fantastic.  The Feb2020 Stereo Coffee shows how well recorded a lot of music was! 

The sound is very very big with a very wide and deep sound stage and with really stable and sharp stereo imaging for both the singer and all the instruments.


I suspect that the latest Stereo Coffee is the best, or if not the best, right up there with the very best passive pre-amps in the world.

 
Geoff Lee
Melbourne
Australia

Edited by Synthesis
To make my intent clearer.

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1 hour ago, Synthesis said:

This is a review of the sound of the Feb2020 version of the ‘Stereo Coffee’ passive pre-amp.

I first listened to the ‘Eurythmics: Ultimate Collection’ which is very well recorded with a big almost electronica type sound on some, but not all tracks. Annie Lennox’s vocals feature prominently on most tracks. Already very strong the latest Stereo Coffee is a surprisingly big improvement on the excellent 2019 version.

The improvement is that the mid-range (especially the vocals) are more  prominent in a good way i.e. the human voice bounces out from the backing instruments. The vocals sound like I assume that they sounded when they were recorded in the studio.

But this also applies to the backing instruments because they are ALSO more prominent and more like I assume they sounded in the recording studio! 

I would describe the sound overall as:

1. Greater separation between the vocals and individual instruments, and between the
    individual instruments themselves.
2. Greater realism of the voices and instruments which gives a very 'clean' sound.
3. A very 'dynamic' sound i.e. the vocals and the instruments are very dynamic.


Next I listened to a jazz album by Patricia Barber called ‘Modern Cool’ and it was simply superb on the Feb2020 Stereo Coffee and the Amp Camp Amp V1.6 Class A power amp. What a combination!

It was like being in a small jazz venue it’s so realistic.

The quietness around voices and instruments is uncanny - I could actually hear the clock ticking in the next room in quiet passages!

I suspect that the latest Stereo Coffee is the best, or if not the best, right up there with the very best passive pre-amps in the world.

 
Geoff Lee
Melbourne
Australia

Thanks Geoff for that reflection.

 

I’m looking forward to the privilege of implementing Chris’ StereoCoffee soon.
 

shane 

hobart

tasmania

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I am looking for something to increase the output from my phono amp. Does the stereo coffee increase the impedance at all. I am using the passive volume control on the phono amp straight to a power amp and its nice but doesnt have the drive of when I put my valve pre amp in between.

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3 minutes ago, McCvinyl said:

I am looking for something to increase the output from my phono amp. Does the stereo coffee increase the impedance at all. I am using the passive volume control on the phono amp straight to a power amp and its nice but doesnt have the drive of when I put my valve pre amp in between.

Presumably you mean you want to decrease the output impedance or increase the output to drive your power amp better. Unfortunately, a passive attenuator can only do the opposite. You need an active preamp or more sensitive power amp to achieve that.

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Yes, thats right. Well read Con. Is there anything other than a full blown active  preamp that could achieve what I am after.

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