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Old 14th July 2012, 05:09 PM   #6231
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Litle one is gone to wisit neighbours for a few minutes so small update.

as I said both boards up and running and yes got them connected nothing definitive so far just Oscilloscope trough passive anti RIAA they both loock fine.

So Just my one mistake with an inverted capacitor othervise it would have been they work fine from start for me as well.

Just in case one strugle with heat sinks clamps for the TO220 I got solution to make thing child play.

PS I set V outs so to have 17.5 +- at OP amp pins
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Last edited by Bksabath; 14th July 2012 at 05:12 PM.
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Old 14th July 2012, 05:33 PM   #6232
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Cute, and good idea to stuff the cooling finn.
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Old 14th July 2012, 05:56 PM   #6233
hesener is offline hesener  Germany
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Quote:
Originally Posted by Bksabath View Post
Litle one is gone to wisit neighbours for a few minutes so small update.

as I said both boards up and running and yes got them connected nothing definitive so far just Oscilloscope trough passive anti RIAA they both loock fine.

So Just my one mistake with an inverted capacitor othervise it would have been they work fine from start for me as well.

Just in case one strugle with heat sinks clamps for the TO220 I got solution to make thing child play.

PS I set V outs so to have 17.5 +- at OP amp pins
grrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrreat!!!!


PS: loosk like the little one is getting the audio virus too......
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Old 14th July 2012, 09:00 PM   #6234
RCruz is offline RCruz  Switzerland
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Quote:
Originally Posted by Bksabath View Post
Let There Be Light!

Well almost...
Little fault finding on second be fun…
Both boards are stuffed








Tanks Ricardo for posting the calculated RIAA values.
I think that I will find difficult to ear much difference but at least I know which way to go if I have to round things up.
For example I did not have enough 147 K so I used 165K And 511k Which I had in my draw this give me 67K instead of 73.5K

Ricardo posted the following in post 6150
Quote> for 33.3n I get 9.545kr, 11.42n and 65675r (instead of 73.5k)

They will be changed to 147K to keep things as on spec ASAP.

….
I would not change the 73,5k r for now (I believe these are ok because of the interaction of first mirror output imp and second stage buffer´s imput imp).... the most important values are 33.3n and 9549r because these will define the 500.5Hz point
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Last edited by RCruz; 14th July 2012 at 09:05 PM.
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Old 14th July 2012, 09:20 PM   #6235
RCruz is offline RCruz  Switzerland
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Quote:
Originally Posted by Joachim Gerhard View Post
As far as i can tell the Boboli has 1.5mV nominal output. Plus 20dB can be cut at certain frequencies so it will put out 15mV on the highest peaks. Say we have 60dB of gain, we end up with 15 V at the output ! The Paradise can throw 15V P-P so on the highest peaks it will just not overload but you end up with a lot of voltage before the preamp. The 150 Ohm may certainly need a coupling cap.
So I should use a coupling cap just to be sure the cart is not affected by input offset.... but what about the possibility of the paradise outputting 15V... what harm can that cause to the following preamp ?
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Old 14th July 2012, 09:21 PM   #6236
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15V ? There is something wrong.
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Old 14th July 2012, 09:22 PM   #6237
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Sorry, i thought that was DC offset at the output !
When the pamp has a potmeter at the input it will work. You just have to turn it down quite a bit.
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Old 15th July 2012, 08:36 AM   #6238
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So you where talking about output offset... ok
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Old 15th July 2012, 12:56 PM   #6239
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I repeat : The Paradise should not have much DC offset at the output but there can be a lot of AC voltage on peaks when you use a cartridge like the Boboli.
That will not destroy the following buffer or preamp but can overload the power amp.
So best you put a pot meter before the stage that follows the Paradise.
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Old 15th July 2012, 01:24 PM   #6240
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Ok sorry for the misunderstanding. Off course I will use a pot between the paradise and the buffer before the power amp.

As for imput offset, I will experiment with a DL160 that has similar output as the boboli and see what is the outcome before I go meet my friend
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