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Building a Pearl 2
Building a Pearl 2
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Old 11th May 2019, 05:57 PM   #1331
Enochrome is offline Enochrome  United States
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Join Date: Nov 2011
Quote:
Originally Posted by jackinnj View Post
Gain of the second stage is 40dB, first stage (net of the RIAA network) of 15dB = 55dB -- you need to get the second stage gain up to 52dB. You can try 270R and 220R for R14.

I would short the input of the phono preamp, and look at the output to make sure that it isn't oscillating with the second stage gain so high. I would be happier if you used a step up transformer. (I can look at it with my Pearl next week with the network analyzer to check for stability.)




Depends upon the leakage inductance of the transformer you're using, the judgment isn't generic.
Thanks for the information and sorry for the late reply. I will most likely reconsider the use of such high gain and most likely do 65db of gain. With that much gain, I think that my preamp can make up the difference (I hope). I don't want to add any issues for the sake of more gain.

Thanks again. I'm sure you will see more posts in the near future because I am dedicating next to the build.
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Old 12th May 2019, 01:12 AM   #1332
exojam is offline exojam  United States
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Almost finished repopulating the Pearl Boards, forgot to order the 221 ohm resistors I wanted and some standoffs for Rx and Cx. I will need to build little shelf’s on the chassis sides for C1 and C26.

B1 is completely redone besides the volume and switch wiring.

Probably tomorrow I will look at getting the power box stated. I will need to do a dry fit for everything in it before getting the components in permanently.
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Old 15th May 2019, 02:45 AM   #1333
exojam is offline exojam  United States
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Russellc,

I have a few question’s for you if you do not mind.

In the first attachment:
What is the device circled in white?
It looks like main power coming in but what are the two red wires that I marked in yellow.
Same goes for the wire I marked blue. I believe it is the ground from the main power but not know what that little device is with the two red wires on I just want to be sure.

On the second attachment:
What wires are those that I put a blue line next to? It almost looks like they go under the board but am not sure.

And just a general question.
The secondaries coming off of the transformer and go under the power board, are both the blue and green wires getting hooked up to the board under there?

Thanks, James
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Old 16th May 2019, 11:47 AM   #1334
exojam is offline exojam  United States
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All set, found the answer to my question.
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Old 19th May 2019, 04:07 AM   #1335
exojam is offline exojam  United States
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Quote:
Originally Posted by jackinnj View Post
The Pearl will easily overload with MM cartridge.

Here are the correct RIAA values -- :
I am wondering if anyone made the changes to the values of the components listed in this post? Thanks.

I have attached the screenshot from the post showing the new values.
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Last edited by exojam; 19th May 2019 at 04:11 AM.
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Old 19th May 2019, 04:16 AM   #1336
exojam is offline exojam  United States
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Can someone please show me where the .22uf film snubber caps are installed? The reason I ask is I will not be using the same power supply setup shown by 6L6 in the first post.

I will only be using one 35 amp bridge where his drawing shows two of them. Thanks.

Last edited by exojam; 19th May 2019 at 04:18 AM.
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Old 19th May 2019, 08:10 PM   #1337
jjacek is offline jjacek  Sweden
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Location: Malmö
Default :)

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Old 20th May 2019, 11:51 AM   #1338
exojam is offline exojam  United States
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Looks very nice, like that Mundoff. What is the manufacturer of the red caps.

I have the same little PCB holder and love that little thing.
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Old 20th May 2019, 12:28 PM   #1339
Mark Johnson is offline Mark Johnson  United States
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They look like these to me.
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Old 20th May 2019, 01:17 PM   #1340
Wellerman is offline Wellerman
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Quote:
Originally Posted by exojam View Post
I am wondering if anyone made the changes to the values of the components listed in this post? Thanks.

I have attached the screenshot from the post showing the new values.

Yes, I did. I made some (many) modifications to my Pearl 2 (will report later), one of them was changing the values of the RIAA. Because I'm also in the process of installing a new cartridge, I have not had a chance to listen to the result of all the modifications.
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