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Old 29th October 2010, 09:17 PM   #5171
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Quote:
Originally Posted by Salas View Post
Its just a simple phono easy to make, nothing more nothing less. I will start listening to open reel like Sly from now on.
I'd love to see a schematic of the Simplistic RIAA adopted for Reel to Reel Tape playback amp. The difference should be mainly in part of the equalization.

Should you post such a schematic, I promise I'll build it ASAP, attach it to my Revox B-77, post photos and report listening impressions.

I have 100 2SK170BL waiting to be sorted by IDSS, plus a shipment on its' way of another 100 2SK170BL and 50 2SK170GR and 50 2SK170V – so picking up a desired IDSS shouldn't be a problem.
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Old 29th October 2010, 09:22 PM   #5172
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It was a joke about Sly Stone's photo. Having no open reel.
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Old 29th October 2010, 10:30 PM   #5173
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Originally Posted by Salas View Post
It was a joke about Sly Stone's photo. Having no open reel.
I wasn't joking. Do you want the NAB equalization data? As far as I can see, it should be a piece of cake for you to modify the RIAA equalization to NAB.
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Old 30th October 2010, 09:18 AM   #5174
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Originally Posted by nicoch46 View Post
I like alot that spirits... and yours of course
+1
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Old 30th October 2010, 12:13 PM   #5175
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Smile teflons for balanced RIAA

I'm very happy, today received the caps for balanced RIAA: 2 x 47nF & 2 x 15nF

Click the image to open in full size.
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Old 30th October 2010, 04:15 PM   #5176
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Hi Salas, I forgot to thank you for your help and info on the phono stuff. It doesn't look like I will be able to build something in the near future, but when I do I'll be prepared. That circuit must be priceless.

Thanks,
- keantoken
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Old 30th October 2010, 07:48 PM   #5177
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No big deal Kean, you are welcome. I think that the recommended revised circuit will suit your needs for very easy to find BJTs, probably those or equivalent are already in your parts bin. Minimal complexity MM circuit, just one stage and a buffer, and its good enough for your TT. Try it on a perfboard soon.
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Old 31st October 2010, 08:59 PM   #5178
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Came back to the thread today and want to join the chorus to congratulate Salas first of all, then Felipe for his Wiki entry on this project. Well done, because it focuses on the options available for the various cartridge needs.

I'm at the stage where I've modified my two (ikoflexer) riaa boards (now I know there are other/better board options - thanks! Maybe I'll do a second one!). I was reviewing the changes needed for the shunt regulator in post #5120. It seems to me that although it is presented differently it's basically the same shunt circuit (with the IRFP at the output dc) with the difference that instead of a zener, Salas has introduced a trimmer. I hope this is correct.

Looking forward to finish the project and report my listening experience.

Regards to all who have made this thread such an interesting and exciting one.

Joe A
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Old 31st October 2010, 09:11 PM   #5179
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Trimmer is better noise, some zeners proved overly noisy in the long run. And there was no way to know. One was behaving the other not.
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Old 2nd November 2010, 11:46 PM   #5180
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Default Shunt regulator problem/s

I’ve just built the Shunt regulator on an Ikoflexer board layout using 3 LEDs (R10 – 1K6 linked), 2 x BF245s, a 10K trimpot instead of D1 – 1N4748A) and a K170 on top of BC550 instead of R4 - 1K8 as per Salas circuit in post Simplistic NJFET RIAA5120. Component references as per post #Simplistic NJFET RIAA682. The circuit I built is not working. Can fellow builders please help me find the problem?

DC Input to the circuit is 33V (at R3-10R 2W). Voltage at the other end of R3 is 28V which is also the voltage at the output. The heatsink on the output IRFP got very hot during the 5 minute testing. Voltage at R7 - 47 ohm (with respect to ground) is 0.62V at both ends. At one point during testing there was some smoke coming out and I quickly switched off. Later I noticed that the 10 ohm 2 watt resistor was slightly blackened. Later I changed the orientation of the leds and C1 across them because I wasn’t sure about them compared to ixoflexer’s silkscreen. Originally I soldered the leds with their +ve leg connected towards R3 (10 ohm) and the –ve end of the string connected to R1 (200 ohm to IRFP9240 gate).

Maybe somebody can give me some indicative voltages at some of the points in the circuit.

Thanks and regards.
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