Here is a build of the 3 input LDR board without the RCA block. Its in a recycled Audio Synthesis PAS02.chassis.
Image shows 3 inputs ,the series LDR pair for the 4th input in this build will be added, I will post another image once this is done.
It shows how the boards can mounted to suit existing rear plate RCA's with the result of a big improvement to a prior switched attenuator type passive pre amp.🙂
Cheers / Chris
Image shows 3 inputs ,the series LDR pair for the 4th input in this build will be added, I will post another image once this is done.
It shows how the boards can mounted to suit existing rear plate RCA's with the result of a big improvement to a prior switched attenuator type passive pre amp.🙂
Cheers / Chris
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Regarding Power supplies, we have had questions concerning battery use, or plugpacks, for our range of kits available from as little as $95.00 + postage for our Single LDR Kit and only $155.00 for our 3 input model + postage. The 3 input has 8 LDRs all matched and the Single 4 matched LDR's
Available now at: stereo coffee items - Get great deals on items on eBay Stores!
Listening tests confirm the Stereo Coffee LDR kit with matched LDR's to be the best available.
Our advice is the voltage should be 12 volts, a regulated plugpack is an economical and simple choice that we find works very well. Current rating at a minimum for plugpacks we observe is 200ma, with many models higher. Our circuitry draws much less than this. 500ma capability is easy to obtain and we think a good value to settle on.
A battery supply alternatively can be arranged with a switch to charge overnight and the attached diagram shows how this might be arranged. Another idea we like is a solar panel left on permanently to charge a battery of 7 AH, the small rise in voltage is of no concern to our control board.
We are currently investigating build of a headphone amp, and would pleased to hear if this is wanted as a required addition to our kit range.🙂
Cheers / Chris
Available now at: stereo coffee items - Get great deals on items on eBay Stores!
Listening tests confirm the Stereo Coffee LDR kit with matched LDR's to be the best available.
Our advice is the voltage should be 12 volts, a regulated plugpack is an economical and simple choice that we find works very well. Current rating at a minimum for plugpacks we observe is 200ma, with many models higher. Our circuitry draws much less than this. 500ma capability is easy to obtain and we think a good value to settle on.
A battery supply alternatively can be arranged with a switch to charge overnight and the attached diagram shows how this might be arranged. Another idea we like is a solar panel left on permanently to charge a battery of 7 AH, the small rise in voltage is of no concern to our control board.
We are currently investigating build of a headphone amp, and would pleased to hear if this is wanted as a required addition to our kit range.🙂
Cheers / Chris
I've just built a single input kit from Chris and he couldn't have been more helpful or accommodating. The kit arrived in good time from Australia, was relatively easy to build, but Chris is looking at making the instructions even easier to follow.
Just fitted the 250K pot and I've changed the internal signal wiring to Kimber and it is really singing. The level of detail and the speed of the percussion is fantastic. The difference in quality from the Bottlehead Extended Foreplay III is quite marked and I'm hearing details that I didn't know were there, in records that I have listen to for 25 years.
The change from active pre to LDR passive pre is similar to the change from a radial tracking arm (Linn Ekos) to a linear tracking arm (Trans-fi Terminator), in so much as it made the old one sound like a joke! At this stage I cannot praise it highly enough, I'm hoping it will burn in and settle down a little, but I feel that if it doesn't then it must be something else in the system and not the LDR.
I will post some pixs of the pre-amp and the box I've put it in, but it looks very nice and it is easily the neatest DIY project I've done, probably because there's not too many components in it!
I'll post some pix soon and more impressions of the amp.
Cheers John
Just fitted the 250K pot and I've changed the internal signal wiring to Kimber and it is really singing. The level of detail and the speed of the percussion is fantastic. The difference in quality from the Bottlehead Extended Foreplay III is quite marked and I'm hearing details that I didn't know were there, in records that I have listen to for 25 years.
The change from active pre to LDR passive pre is similar to the change from a radial tracking arm (Linn Ekos) to a linear tracking arm (Trans-fi Terminator), in so much as it made the old one sound like a joke! At this stage I cannot praise it highly enough, I'm hoping it will burn in and settle down a little, but I feel that if it doesn't then it must be something else in the system and not the LDR.
I will post some pixs of the pre-amp and the box I've put it in, but it looks very nice and it is easily the neatest DIY project I've done, probably because there's not too many components in it!
I'll post some pix soon and more impressions of the amp.
Cheers John
Thanks John
Stereo Coffee LDR Preamp Kits, http://stores.ebay.com.au/stereo-coffee is early next week releasing a small but important update to our control board. As well as new boards from today onwards ,we will be of course updating for free all of our existing customers with new control boards including shipping cost, ie our customers pay nothing.
We invite our customers to contribute to the forum with their thoughts and findings with this update, delivery we anticipate should occur toward end of November.🙂
Regards / Chris and Dorothy
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Hi Chris!
After an initial problem solved thanks to your help (THANK YOU), I was finally able to listen to your LDR
I have listened all night your LDR without sleep... 🙂
One of my Systems i think it's optimal for LDR, because i have an output source of 25 ohm (a heavy modded Copland CDA 266) and input ampli (Penasa/Freeman My Ref FE) is 100K
Loudspeakers Opera CALLAS, a 2way with Scanspeak Revelator drivers
With your LDR i have from Off (real no sound) to Max , stereo image it's perfect to all positions of Volume, no imbalace
Sound was incredible! Clean, detailed, without any form of distortion
the ambience it's palpable, you can hear the walls of room where music was recorded
Soundstage is REAL with all armonics fulfill my room
I can go to Max volume without any compression or distortion of sound
Voice and string are Here in my room!
There is NO MATCH versus my others attenuators (1 Shunt with Shalco switch and Takman resistor in shunt and a Texas TX 2352 serie resistors - 1 Stepped with SMD resistors and another LDR with famous scheme of George Stancheff but no good matched LDR)
Your LDR it's clear superior, it's no possible to go back because i'm loosing too much SQ
Your Control board it's responsible of this wonderful sound?
what is, a Voltage Controlled Current Source?
New control board do better?
Thank you very much!
Marco
After an initial problem solved thanks to your help (THANK YOU), I was finally able to listen to your LDR
I have listened all night your LDR without sleep... 🙂
One of my Systems i think it's optimal for LDR, because i have an output source of 25 ohm (a heavy modded Copland CDA 266) and input ampli (Penasa/Freeman My Ref FE) is 100K
Loudspeakers Opera CALLAS, a 2way with Scanspeak Revelator drivers
With your LDR i have from Off (real no sound) to Max , stereo image it's perfect to all positions of Volume, no imbalace
Sound was incredible! Clean, detailed, without any form of distortion
the ambience it's palpable, you can hear the walls of room where music was recorded
Soundstage is REAL with all armonics fulfill my room
I can go to Max volume without any compression or distortion of sound
Voice and string are Here in my room!
There is NO MATCH versus my others attenuators (1 Shunt with Shalco switch and Takman resistor in shunt and a Texas TX 2352 serie resistors - 1 Stepped with SMD resistors and another LDR with famous scheme of George Stancheff but no good matched LDR)
Your LDR it's clear superior, it's no possible to go back because i'm loosing too much SQ
Your Control board it's responsible of this wonderful sound?
what is, a Voltage Controlled Current Source?
New control board do better?
Thank you very much!
Marco
Hi Marco
Thanks for your kind words. A Voltage controlled current source is a type of circuit where a small voltage input then controls a current source load. You may find a op amp, a transistor and resistor sensing, as key parts of a VCCS
The low output impedance capability of your Copland is very similar to a DBX150x that we regularly use.
Its wonderful when you really get to hear the music including choices the artist made of acoustics and instruments. One of our favorites to hear is the Palladian Ensemble on Linn CD's, the Stereo coffee preamp provides everything that was recorded.
The control board is very much responsible for the excellent sound we achieve, as well as many hours of careful matching of LDR's.
Thanks for asking about the new control board it narrows down the LDR L/R difference further still, and also lowers the voltage across the LDR's we are now measuring 1.723v as maximum voltage. We are of course, attending to delivery of the new control boards to our existing customers as a priority. 🙂
Cheers / Chris
Thanks for your kind words. A Voltage controlled current source is a type of circuit where a small voltage input then controls a current source load. You may find a op amp, a transistor and resistor sensing, as key parts of a VCCS
The low output impedance capability of your Copland is very similar to a DBX150x that we regularly use.
Its wonderful when you really get to hear the music including choices the artist made of acoustics and instruments. One of our favorites to hear is the Palladian Ensemble on Linn CD's, the Stereo coffee preamp provides everything that was recorded.
The control board is very much responsible for the excellent sound we achieve, as well as many hours of careful matching of LDR's.
Thanks for asking about the new control board it narrows down the LDR L/R difference further still, and also lowers the voltage across the LDR's we are now measuring 1.723v as maximum voltage. We are of course, attending to delivery of the new control boards to our existing customers as a priority. 🙂
Cheers / Chris
Just fitted the next control board and the clarity has gone up another level. The bass is easier to follow, with much more control and from the very quick listen I also think that the soundstage has spread across the room even further.
Excellent work Chris and thanks again for all the help.
John
Excellent work Chris and thanks again for all the help.
John
Hi to all at diy-audio, I have just completed Chris's LDR 3 input pre-amp kit, swapped it in for my ARC sp6b and can't quite believe how good this pre-amp sounds, a dead quite background with wonderful alive music coming form my moded Acoustat 2+2's, the source is a home made turntable and arm with a rebuilt Fidelity Research FR7 cartridge, Graham Slee Equator/Revelation phono stage. I can't thank Chris enough for all his help to build this kit and the beautiful music that i am now enjoying, so thank-you Chris and i highly recommend this Pre-amp to all. Cheers, Gary
Thanks Gary
Its a very exciting time for us, as we are releasing our Model C which we call the Stereo Coffee Cappuccino. our apologies for delay, but as Eric Burdon once said "it will be worth it " ( song San Francisco )
We are working hard getting this new board to everyone. We look forward to appraisals.
Cheers / Chris
hi, are you planning a "balanced" version of this kit ? thank's and good luck with your venture.
Yes we can do a balanced version, Based on a double L pad, will suit our control board(s). Look forward to assisting you.
Cheers / Chris
Far better audio quality. We have carefully looked at model A and model B whilst some circuit values remain- as they were right in the first place, we now have a circuit that is perfect for LDR's
Cheers / Chris
Hi Everyone
Some very interesting developments have occurred. Some email exchanges with Marco asked some interesting questions, so Thanks Marco.
When kit constructors receive their Type C boards, they should wire from Left and Right connections of the potentiometer a series resistor of 1K in parallel with a red LED, that is an LED and 1k resistor to the shunt board Anode connection, and a Red LED with a parallel 1k resistor to the Series anode connection. the central pot connection of course is connected to the control board out
Orientate each of the LED's so that anode comes from the pot, and cathode goes to each Anode connection.
We will test type A and B boards to ascertain if these can be done too.
The new Type c boards add another 1k and red LED prior to the diode board connection. as well as a Zobel network, and a series resistor prior to the current regulator - setting an overall board current of 45ma, prior to other current regulation.
Cheers / Chris
Some very interesting developments have occurred. Some email exchanges with Marco asked some interesting questions, so Thanks Marco.
When kit constructors receive their Type C boards, they should wire from Left and Right connections of the potentiometer a series resistor of 1K in parallel with a red LED, that is an LED and 1k resistor to the shunt board Anode connection, and a Red LED with a parallel 1k resistor to the Series anode connection. the central pot connection of course is connected to the control board out
Orientate each of the LED's so that anode comes from the pot, and cathode goes to each Anode connection.
We will test type A and B boards to ascertain if these can be done too.
The new Type c boards add another 1k and red LED prior to the diode board connection. as well as a Zobel network, and a series resistor prior to the current regulator - setting an overall board current of 45ma, prior to other current regulation.
Cheers / Chris
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Hi Everyone
We are just investing what is the best combination, LEDs at the anodes appear to create too wide a sound stage, will report as soon as we have the answer,
Cheers / Chris
We are just investing what is the best combination, LEDs at the anodes appear to create too wide a sound stage, will report as soon as we have the answer,
Cheers / Chris
Hi Everyone
The best combination is the aforementioned LED in parallel with a 1k resistor at V+ on the control Board, being fitted to all model C, The anodes ends are different, the best combination appears to be a 1N4148 diode arranged with its anode from the pot and its cathode to the LDR board in parallel with a 470R. Will report if there is any change.🙂
Cheers / Chris
The best combination is the aforementioned LED in parallel with a 1k resistor at V+ on the control Board, being fitted to all model C, The anodes ends are different, the best combination appears to be a 1N4148 diode arranged with its anode from the pot and its cathode to the LDR board in parallel with a 470R. Will report if there is any change.🙂
Cheers / Chris
Hi Chris, when will the balanced version be available for sale ? I am actively looking for a replacement for a passive pre which gobbles up a lot of information at lower levels.
edit: I'll even beta test it for you on a hypex ucd ;-)
Thank's
rupert
edit: I'll even beta test it for you on a hypex ucd ;-)
Thank's
rupert
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Hi Rupert
How many inputs are needed ? I can have the balanced version by Wednesday this coming week, at the Stereo Coffee Shop stereo coffee items - Get great deals on items on eBay Stores!
Cheers / Chris
How many inputs are needed ? I can have the balanced version by Wednesday this coming week, at the Stereo Coffee Shop stereo coffee items - Get great deals on items on eBay Stores!
Cheers / Chris