Chris Daley's Stereo Coffee Preamp

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Chris Daley Stereo Coffee preamp. I run a 4 way active system using JBL drive units. I input via a Laptop, DAC, Passive Pre Amp, Marchand Crossover, Amps x 4. Speakers. I am highly sceptical of any review so with that in mind I’m giving my opinion of Chris Daley’s Stereo Coffee Preamp. Firstly I have tried a number of Passive Preamps, Nano Patch, Active, Stepped Attenuator and finally Mod Squad Passive.

The Mod Squad had been Reviewed (yes I do read them) being put up against some high end Preamps and came out highly recommended. After reading various articles I was going to order Georges unit but when a second hand one came up I asked the seller what he was replacing it with? “The Stereo Coffee Preamp was the reply”.

So after a lot of emails and time I got Chris Daley to build one and it came on Friday with a £27.00 handling charge via Parcelforce! After getting the unit running, there was a glitch with the input switch, I put some music on ripped from CD. The first thing that was apparent was the bass, not subtle it was outstanding. Keep in mind I’m running a pair of JBL 2245 18” so have heard nice bass before. It just seems clean and effortless. The rest of the sound spectrum cleaner more precise.

Hell I hate reviews so much ******** but there we go. So it seems replacing a very simple resistive Volume Control with a LED unit makes a vast difference to the quality of the sound. A very well worth while upgrade particularly for those expert enough to buy the kit. Congratulations to Chris Daley for all his work over the years with an outstanding result.
 
Equally it suggests to apply that capacitors present capacitance, and this thread with numerous findings of difference, also it follows, must similarly then, make no sense ? Petp Capacitors-one Of The Best?

Perhaps there is more than just Ohms law, that can help us express differences of chemical properties of materials involved with resistance ? If not it suggests we would tend to see perhaps only one or two materials used for resistors and not the multitude that are available. YouTube
 
Do have opinion on what i raise at #4 ? . That if your comment at #2 is correct " Otherwise it makes no sense Resitive unit or led unit, they both present resistance "

the thread finding difference in capacitors it follows, must also make no sense

Meaning its OK for Capacitors to have difference, which is almost celebrated in the thread, but resistors cannot have any difference. Specifically concentrating on resistance, would you agree the chemical properties of different types of resistors have different audio qualities ? Or are resistors no matter what they consist of, all the same ?

Why
 
This will descend into unfortunate bickering and entrenched encampments unless someone can provide verifiable, non-anecdotal data for the audible difference between LDR and a resistor.

From what I gather the LDR is also inherently nonlinear.

All the LDR related threads have ended similarly, with all the LDR producers like Tortuga and Lightspeed chiming in, and throwing up their hands saying “it’s just better! I heard it!” While also admitting their products performed less than ideal when subjected to thorough testing.

I’m not taking sides, btw. I’m actually in the midst of assembling an LDR for curiosity’s sake.

I’d just like to hear something besides the same song and dance.

There was a linear audio article measuring distortion from a Dale RN60E that was -140db down or thereabouts. Are you suggesting that’s audibly different?

Can you offer something besides conjecture?
 
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So the answer is no.

The burden of proof should be on those manufacturing and selling these items as superior. Making claims requires evidence. To say that science is not sophisticated enough to answer such questions is just plain delusional in light of instrument resolution today.

If there is any metric which an LDR exceeds the ability of a ladder attenuator with 50ppm .1% resistors I am eager to see it.

My comparison will not be A/B/X nor will it have the same gain stage or buffer as other preamps I have, making a fair comparison presumptuous. It will be for simple remote volume control in my office and was chosen for low cost, screen readout and remote capability- the LDR just came along for the ride. I was also partly interested in using it to break in my new soundcard / measurement interface.

All LDR measurements I’ve seen show substantially inferior results to a ladder or stepped attenuator with a buffer.

If you could provide some evidence for your claims it would certainly be a wise business move. I don’t see any reason to not provide data except that it’s something you’d like to hide or something you don’t have the sophistication to accomplish.

Anecdotal / testimonial-based evidence of superiority, suggesting that the superiority is scientifically “unexplainable” (ie magic), claims that substantiated evidence is unnecessary, and claiming that you will not understand why it’s superior until you own/experience said product are all basically checklist hallmarks of consumer / marketing fraud according to the Federal Trade Commission.

Under the Federal Trade Commission Act evidence is a requirement to advertise a claim that one product is superior to another for a reason.

(Also, hence the audio “reviewer” model which neatly circumvents this, channeling claims through a third party and then reimbursing that third party via advertising dollars and other rewards.)

Lucky for some since audio gear doesn’t cause cancer and children don’t choke on it it’s largely unlitigated.

Also, on an unrelated note it boggles my mind how quickly manufacturers swoop into threads when reviews of their products appear. To me, that means it’s not as casual as one might imagine.
 
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The suggestion remains to find out for yourself, by not succumbing to thinking a 7805 will do, I predict it will be a revelation for you finding how wrong that part is anywhere near a LDR anode and cathode. You only need a single gang potentiometer, You also need to avoid any capacitance following the initial power supply, particularly in parallel with the anode and cathode.

As I understand this is a DIY forum, and therefore the challenge awaits, looking forward to your findings.
 
I find it amusing that people will obsess about using this expensive resistor or that expensive resistor in their circuits (to minimise distortion), but will then happily use a known non-linear resistor for volume control just because it happens to be light-dependent and someone told them it sounds good. Some LDR volume control vendors have at times confused control linearity with signal linearity (or at least made statements which are sufficiently ambiguous that a non-technical buyer might confuse the two).

Of course a well-designed LDR volume control (e.g. Lightspeed) fed a sufficiently small signal will add sufficiently low distortion that it may not be audible, yet I retain a sneaking suspicion that the popularity of LDR controls may be partly due to some people preferring a little low order distortion.
 
How do you really know unless you actually listen, I recall we had this same discussion about 8 years ago, and you would not listen then, the same as you assert you don't want to listen now. Can you provide me a few words that describe this attitude problem to listening, as it was very strange then, as it is now.

Are switch contacts or wiping surfaces with audio signals linear. ? History shows Mary Greenwalt's invention the rheostat, was designed for altering light display not audio, and audio preservation was never properly considered,
 
Chris Daly said:
I recall we had this same discussion about 8 years ago,
I am not sure it is as long as 8 years ago. I do remember trying to explain to you back then that the output from an opamp should normally be taken from the output pin, not an input pin, and that randomly scattering diodes around a circuit (some of which are always reverse biased) does not necessarily improve it. I assume you now have a better grasp of circuits?

A volume control is essentially a variable potential divider. For best results the resistors either need to be very linear, or have identical nonlinearity. Interestingly, a normal linear pot does this; not sure about a 'log' pot.
 

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As usual , as sarcastically as i can write - this comes from listening to each ?

Yes.

Down at 0.1V through 22k, a resistor-opto attenuator has no gross distortion; at 3V through 2K the distortion was audible.

An opto-opto attenuator (WITH zero source and infinite load) would cancel the distortion when set for -6dB (or true 0 dB or infinite atten); I'm not sure about cancellation at other settings.

Buyers want to believe what they want to believe, sellers may honestly believe their own impressions; it is not the FTC's job to stomp all over differences of opinions. Even their stepping in Amplifier Power Ratings was, IMHO, over-reaching.
 
Good for you. Otherwise it makes no sense. Resitive unit or led unit, they both present resistance. One can drive crossover, other probably less. Or else.

and over in the Parts a thread entitled Resistor opinion, an opinion on resistors 11 days later apparently now having difference in sound, yet both presenting resistance ? What a difference time makes.

Hi MikeFarad ...

I have been listening to CMF55, CMF60 (TMK non-lead RNxx types), RN55, RN60, RN65D, & RN65E (lowest temperature coefficient) and Charcroft CAR/S which are similar to the TX2575 (Z-foils).

IMHO the RN65E is the second best sounding in terms of resolution & nuance whereas the Charcroft CAR/S somehow is in a different league. Very revealing, nuanced and with a tonal detailing that I did not hear in the RN65E.
 
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You are quoting two different people?

I think that would indicate a difference between two individuals, not a difference which time makes.

In addition implementation is not described, nor are upstream or downstream components, so without context there can only be general conjecture.
 
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