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Old 26th January 2009, 02:53 AM   #91
GaryB is offline GaryB  United States
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Default updates?

Stefano,
I recently pulled the ONO out and put it back in my system. I decided to try out an old MM cartridge that I had - the Grado 8MX. My NYAL Super It has too much gain for this cartridge so I switched to the ONO. The Grado likes a load of 10k ohms instead of the traditional 47k ohms, so I had to do a bit of soldering to get this right. Once I did that, the sound was really outstanding. I'd forgotten how good this phono stage can sound.

How are you doing with your ONO?

---Gary
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Old 26th January 2009, 07:16 AM   #92
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Hi Gary,

thank you very much for your interest.
I appreciate it.

I have lots of updates.

Lets start:

I tried the circuit I have attached on this 3d few weeks ago and the sound with my Denon DL103 was "excellent".
The quote is because the circuit was on a breadboard and since RIAA accuracy wasn't precise but still overall sound was natural probably due to the topology of the network.

After have been run this test, I decided to seriously work and improve the curcuit.

So i started to evaluate the amplifier before closing it on the RIAA.

I found frequency response not to be so extended.
Poor square wave response.
The amp, needs a compensation cap as the majority, of course, to introduce the dominant pole and shut down overshoots.

I basically didn't like it whatsoever and so i decided to change it.

Therefore i decided to go off on my own and build a completely new circuit.
In the past 3 weeks of work I finally came out just 2 days ago and perfect it yetsterday with a great ciruit on the breadboard.
Bandwidth at -3dB of the amplifier is 2.8MHz.
Hard work indeed and I am pleased with this.
There is stability on the DC offset and excellent low noise.

I am super proud of the technical aspect of my circuit.

No need for compensation cap.

Square wave is sharp and NO overshoots whatsoever.
I have to finish working on it and i will have to listen to it.

I also got a good soundcard after lots of research and an excellent program to match it that hopefully will allow me to do precise THD measurements and frequency response and thus allow me to build a very accurate RIAA network and to tweak the circuit for minimum distortion.
This plan sounds really interesting .

Alright, i have definitely written too much.


Thank you gary for your interest and i am glad you enjoyed your ONO.
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Old 30th January 2009, 05:29 AM   #93
GaryB is offline GaryB  United States
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Stefano,
Congratulations on the good progress. You should think about posting details of your modified circuit so that other people can see what you've done.

Thanks,
---Gary
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Old 20th May 2009, 11:07 AM   #94
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ok...

it's been awhile since my last post on this thread.
The phono stage is nearly completed.
In the next weeks i hope i will be able to come out with a working layout.
The circuit has been developed on the breadboard!! It's finally time to finalize it.

Some data:

- it is a 67.5dB 2 main gain stages.
- passive RIIA deemphasis network
- Measured RIIA accuracy within audible band is down to 0.05dB (yeah I know it is an incredible results for a one step network)
- no saturation even at frequency over 40KHz (no need to get so high though )
- frequency response is 0.7Hz -1.8MHz
- THD @1KHz 2.5Vpk-pk is < 0.02%
- no compensation cap on the circuit due to proper selection of parts for the various tasks and proper feedback; no cap for unity DC gain either
- DC offset, when phono is properly cased, is less than 2mV so far so good
- i have choosen to cap couple the 2 stages instead of developing a servo control system
- feedback factor is around 8dB
- circuit's parameter like biasing of the stage feedback factor where evaluated in terms of distortion improvements and during long listening tests.
- noise of the phono is good. i can only scope a 3mV pk-pk total noise after experimenting with many star point ground's startegy i could implement on the breadboard; i think i can ge a little better with a good layout and proper shielding. Anyways no audible noise from 2 steps away from the speakers and just a little hiss on the tweater at maximum volume withe the hear by.

what else can I say? the sound is excellent. I am a very piky and demanding person so it took me so long to develop something that i can considered to be an reference phono stage (at least for me and for the few others that had the chance to listen to it already).

More folks will follow as the project will be finalized.
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Old 14th October 2009, 11:28 AM   #95
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Hi everybody,

for whom of you who's interested, I finished my phono stage.
You can find the pics on this thread:

http://www.diyaudio.com/forums/solid...ml#post1949754

finally it's is done....I am very happy of it.
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Old 14th October 2009, 03:21 PM   #96
GaryB is offline GaryB  United States
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Quote:
Originally Posted by Stefanoo View Post
for whom of you who's interested, I finished my phono stage.

finally it's is done....I am very happy of it.
Stefanoo,
Congratulations. It looks very pretty and I'm sure it sounds as good as it looks.

It would be in the spirit of Diyaudio to share the details of the final circuit. We have had many good discussions in this thread and I think that you've learned some good things from the different people here.
Please consider giving something back.

Regards,
---Gary
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Old 14th October 2009, 06:44 PM   #97
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Quote:
Originally Posted by GaryB View Post
It would be in the spirit of Diyaudio to share the details of the final circuit. We have had many good discussions in this thread and I think that you've learned some good things from the different people here.
Please consider giving something back.

Regards,
---Gary
Thanks Gary for your compliment. It is true....I have learned very much from different people on this forum. I think that's the purpose of sharing information with one another....to learn. As I mentioned on the other thread, I am hoping to commercialize my project...we'll see....so right now I am not in the disposicion to share "details" (schematic, topology, etc..). But we'll see in the future. What I would REALLY like to do....would be to have some of you listen to it.

Thanks for your interest Gary.
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