Light Dependant Resistor 3 Input Preamp Kit - Page 3 - diyAudio
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View Poll Results: What is reasonable to pay for a LDR 3 input Kit
$150.00 12 75.00%
$180.00 2 12.50%
$300.00 2 12.50%
Voters: 16. You may not vote on this poll

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Old 30th September 2013, 11:21 AM   #21
diyAudio Member
 
Join Date: Sep 2004
Location: New Zealand
Quote:
Originally Posted by awty View Post
Chris I built your LDR to be used with a future kit amp I'm going to build and its just temporarily connected to SS amp built by Richard McDonald in Adelaide which already has volume control, not sure how its configured, but as Richard hand wires everything point to point and is a minimalist , I'd assume it is passive. Amp only has one pair of RCA connectors.
Been busy with work and haven't had a great deal of time to listen to music. I haven't got much to compare with either. Give me some time and I probably can give a better opinion.
But I will say for now, it certainly doesn't seem to detract from the sound of the amp. Volume is even and continuous, balance seems to be spot on (I've heard that balance can be a problem with LDR's) everything is clear and precise, plenty of wide open soundstage, its quiet.....Tiss good am happy. Cant wait to hear it coupled to its own amp.

BTW is there a shelf life with LDR's?
Hi Paul
Thats a very promising review, and i look forward to when its coupled to your new amps.

Shelf life is very long 25-30 yrs and of no real concern particularly if you leave the volume control slightly on when not in use rather than fully off ie at position two or three compared to a normal volume setting. The preamp will provide a very long life of music enjoyment, probably longer than any other component in your audio system.

Cheers / Chris
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Old 3rd October 2013, 01:56 AM   #22
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Join Date: Sep 2004
Location: New Zealand
We have had a few questions and sales from customers wanting their 3 input and single input preamp matched LDR kits, to be made without the RCA block, so that wire can be soldered directly onto the board.

There is good provision on the board for this,and we are happy to do this,at slightly reduced cost, providing a modest refund via paypal following sale. Simply message when checking out if this is required,

Cheers / Chris
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Old 6th October 2013, 09:53 AM   #23
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Join Date: Sep 2004
Location: New Zealand
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
Attached Images
File Type: jpg 2013-10-06-190555.jpg (173.0 KB, 505 views)

Last edited by Chris Daly; 6th October 2013 at 09:59 AM.
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Old 14th October 2013, 05:54 AM   #24
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Join Date: Sep 2004
Location: New Zealand
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
Attached Files
File Type: pdf Switch for Charger & LDR.pdf (9.2 KB, 92 views)
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Old 19th October 2013, 06:18 PM   #25
J Leng is offline J Leng  United Kingdom
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Join Date: Sep 2008
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
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Old 31st October 2013, 07:49 AM   #26
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Join Date: Sep 2004
Location: New Zealand
Quote:
Originally Posted by J Leng View Post
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
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

Last edited by Chris Daly; 31st October 2013 at 07:51 AM.
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Old 23rd November 2013, 08:39 AM   #27
suburra is offline suburra  Italy
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Join Date: Aug 2009
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
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Old 23rd November 2013, 11:56 AM   #28
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Join Date: Sep 2004
Location: New Zealand
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
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Old 23rd November 2013, 06:38 PM   #29
J Leng is offline J Leng  United Kingdom
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Join Date: Sep 2008
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
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Old 30th November 2013, 06:21 PM   #30
raeler is offline raeler  New Zealand
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Join Date: Nov 2013
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
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