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Old 25th October 2012, 10:49 PM   #141
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Old 28th October 2012, 06:19 PM   #142
FdW is offline FdW  Netherlands
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Old 28th October 2012, 06:38 PM   #143
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To far avay from Premiere Cru reagion?

Boot full may came handy for crimbo.....
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Old 29th October 2012, 09:11 AM   #144
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Ok, I'm back, hit me (with that review )
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Old 29th October 2012, 10:35 AM   #145
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Prety nice sound out of it so far, no hum, but this is not suprise as it is balanced, I think it need a bit more time to setle in I have used polistirene caps for the RIAA and they take a while, I will tri and change those with same different ones eventualy.

Power supply which cover the 80 %of board space is working realy well and noise level is very low (nedle up) quite plesant noise vise when runningon the blank tracks and no sign of overloading on scratched records.
I had to place a second 20Rin parralel (10R) now to get the gain up with my Elitte and not using any loading at present, Just have to wait for Her shopping Neighbours out to give it a serious going over, still preaty easy build with no fussing about, the only component I had to select where the RIAA caps to get the 2 channels matching.

First listening Impressions
This is purely based on my set up, ancillary equipment my personal taste and same prety worn test gear.

I like it....
More to folow.
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Old 17th April 2013, 07:36 PM   #146
RCruz is offline RCruz  Switzerland
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Old 21st July 2014, 05:51 AM   #147
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Default A few thoughts . . . .

I think you did a fantastic job with the layout and construction of this project. However, I would offer a few observations re the design of the front end. I realize that simplicity was a major goal, but sometimes it takes a little extra circuitry to get the best performance.

Because your input stage uses just one op-amp stage to handle the differential input, you lose a lot of the advantages of using a true differential instrumentation-type configuration using 3 stages. You lost good CMNR (common mode noise rejection) with the low gain. You lose good S/N performance by using 23,500 Ohm resistors in series with each leg (10-13 dB beyond what is necessary).

Also, the input impedance to each leg is not equal and therefore has imbalance that will further degrade noise rejection. Thevenizing the input resistance yields 23,500 Ohms for the inverting leg & 188,500 Ohms for the non-inverting leg. Remember the inverting input pin is at virtual ground!

Using the 3 stage instrumentation amp configuration, you can keep the series resistance as low as possible, keep the resistor values closely matched within 0.1% or better & use high gain with the diff amp to maximize common mode rejection ratio (CMRR). Then, you'll realize the fantastic, low noise performance that a true differential front-end is capable of.

I hope that this helps you and others that desire the advantages of true differential inputs.
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Old 21st July 2014, 07:08 AM   #148
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@bardkallestad, Thanks for your thoughts on this project, as you noticed the main goal of this project was simplicity and sound. Both have been accomplished (I think ), the sound quality has been confirmed by multiple experienced listeners and listening groups. Even the MC version sounds very good although the noise level is a bit higher then needed.

As I have done no electronic design in the 30 years before this one design, then I did do a power amplifier and some line-stuff, my 'return' to electronics showed me the incredible quality of modern op-amps, this made me think 'what can be accomplished with these?', and this RIAA was the result.

Maybe I will have an other look at the 'modern'-op-amp RIAA and design and other one in the future, but at the moment I an real busy with a 'current-conveyor' power amplifier.

Last edited by FdW; 21st July 2014 at 07:11 AM.
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Old 25th August 2014, 10:25 PM   #149
mzperx is offline mzperx  Hungary
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Quote:
Originally Posted by bardkallestad View Post
Using the 3 stage instrumentation amp configuration...
I did it so in my project in order to outperform the simple INA163 phono...
https://docs.google.com/file/d/0BzbI...VrRHJzZVE/edit
Cost and simplicity wasn't object here

Last edited by mzperx; 25th August 2014 at 10:30 PM.
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Old 26th August 2014, 07:25 AM   #150
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Quote:
Originally Posted by mzperx View Post
I did it so in my project in order to outperform the simple INA163 phono...
https://docs.google.com/file/d/0BzbI...VrRHJzZVE/edit
Cost and simplicity wasn't object here
That looks great but such complexity was not in the scope of this project here. This here was to proof (and it did) that a relatively simple opamp RIAA can do the work, and can sound extremely good.
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