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Old 22nd March 2013, 03:51 AM   #31
6L6 is offline 6L6  United States
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Both. One wire is red, one is black. Both to TT ground lug.
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Old 22nd March 2013, 04:21 AM   #32
Mr. dB is offline Mr. dB  United States
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Thanks!
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Old 22nd March 2013, 04:32 AM   #33
6L6 is offline 6L6  United States
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I forgot about this 'awesome' drawing I did in the different Pearl 2 thread -

Click the image to open in full size.

The important thing to remember is that all the connectors are floating. Ground them to the screw in the chassis only as you need to. (which will likely only be 2 things, the AC mains earth/ground breaker bridge, and the phono ground post.)
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Old 22nd March 2013, 10:27 AM   #34
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This was a great diagram that I followed in mine - tomb quiet.
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Old 22nd March 2013, 01:58 PM   #35
Mr. dB is offline Mr. dB  United States
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Quote:
Originally Posted by 6L6 View Post
I forgot about this 'awesome' drawing I did in the different Pearl 2 thread -

Click the image to open in full size.

The important thing to remember is that all the connectors are floating. Ground them to the screw in the chassis only as you need to. (which will likely only be 2 things, the AC mains earth/ground breaker bridge, and the phono ground post.)
I'm building a Pearl Two and a Mezmerize DCB1 at the same time, I was wondering if the B1 will need a diode bridge ground loop breaker too?
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Old 22nd March 2013, 05:17 PM   #36
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Originally Posted by Mr. dB View Post
I'm building a Pearl Two and a Mezmerize DCB1 at the same time, I was wondering if the B1 will need a diode bridge ground loop breaker too?
I was wondering this as well - I think I am going to follow the Pearl 2 PSU diagram for the B1 for the primary side including the line cap. If anything, it may be overkill but only a few $$ to implement.
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Old 26th March 2013, 06:15 AM   #37
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Smile Transformer question..

Hello! great job 6L6.
Im under the impression plitron makes good transformers. Im trying to find the best one i can for my pearl 2 project. Mind sharing your opinions? Anyone.

What do you think of these??

50VA Power Transformer


Or
Is something else likely to sound/perform better in this pass labs pearl 2. The one you suggested in your OP is out of stock...

Thoughts would-be great. Picking a transformer is proving to be a very selective user-taking.

On another topic... Any idea where i could find schottkey bridge rectifiers?? Are there any prebuilt ones or shoud i build my own from diodes..., if so, where would i find a good board for it?

Any upgrade ideas would be great.. For example, I read that putting a suppressor cap type x or x2 across the mains would prevent power switch popping/arching. Thoughts there?

What about adding transistors or resistors after the smoothing caps to reduce noise further.. Is that true? What kind of rating would suit it if so?

Thanks,

Oh i'm new to this forum and this diy audio hobby! Pleased to meet you all.

Formosa
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Old 26th March 2013, 06:47 PM   #38
6L6 is offline 6L6  United States
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Quote:
Originally Posted by FormosaWest View Post

What do you think of these??

50VA Power Transformer
That transformer looks excellent. It will be perfect for the project.


Quote:
Any idea where i could find schottkey bridge rectifiers?? Are there any prebuilt ones or shoud i build my own from diodes..., if so, where would i find a good board for it?
The easiest thing to do is use the Chipamp.com PSU kit for the external powersupply -- Chipamp Power Supply Kit | Chipamp.com

This PSU is essentially perfect for the Pearl 2. It needs an extra jumper and a few things left off the PCB, but you can make the exact PSU as shown in the Pearl 2 article.



Quote:
Any upgrade ideas would be great.. For example, I read that putting a suppressor cap type x or x2 across the mains would prevent power switch popping/arching. Thoughts there?
That is always a good idea, use it!

Quote:
What about adding transistors or resistors after the smoothing caps to reduce noise further.. Is that true? What kind of rating would suit it if so?
It's not necessary, the external PSU is a CR filter with lots of capacitance, and the Pearl 2 PCB has an additional CR filter and regulator for each rail. What you are asking about is already designed into the project!

Quote:
Oh i'm new to this forum and this diy audio hobby! Pleased to meet you all.

Formosa
Wonderful to meet you as well! We are all very glad you are here and building something in this wonderful hobby!

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Old 26th March 2013, 09:38 PM   #39
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Thanks for your reply! I had come across that power supply kit and I'm glad you have given two it thumbs up. Ive just ordered one. The transformer search is still ongoing. I just talked to plitron on the phone and they wanted to suggest a couple or surplus transformers to me. Turns out they have a minimum order usually. Since they are already built and prices are lower, i thought perhaps i could bounce these specs off you and see what you think... They are a little bit off the schematics, and a little larger... so i dnt know ( being a noob) if they will affect the sound quality or gain level of the signal. I lack experience so id appreciate your insights. (My education is in pharmacy, not audio, though thats where my passion is)

These are the specs of the alternatives plitron asked me about. Will they suit this application?

150VA Custom Toroidal Power Transformer. Input: 120V/240V (Primaries must be series or parallel connected) 50Hz 2 Outputs: 22.00V @ 4.10A; 25.00V @ 2.40A. Supplied with standard mounting hardware


230VA Custom Toroidal Power Transformer. Input: 380V 3 Outputs: 12.0V @2.50A; 24.00V @ 4.17A x 2. Potted center.



160VA Power Transformer; Input:115/230VAC 50/60Hz; Output: 2 X 20VAC @ 4.00A; 8%Regulation; Potted Center


So they are certainly a little bigger (right) but is that bad? Im not thinking they are well suited. The fellow i spoke to suggested that the 160 VA 2x20 might be closer to 22volts at a lower load... I not sure what the actual amp load will be, and i planned to stick to the specs, but funny how curiosity can get one thinking about all kinds of little alternatives. But I'm not sure how these alternative transformer sizes might translate to rail voltage after the rectifiers and caps. As you said, we don't want to go too high or low (as the targets are around 26 to 34v or so.)

That extra 12volt output on the 24,24,12 would need to be dealt with as well, and I'm not sure how to handle unused coils safely, and without causing any undue sound issues. Also the input is incorrect, and so on our mains i dont know what that'll look like... Proportionately smaller?

My focus is on getting a nice well performing pearl out of the project and had planned to stick to the basics to avoid creating unique problems.

What do you think?
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Old 27th March 2013, 06:04 PM   #40
AVWERK is offline AVWERK  United States
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Formosawest
You might research R cores or split bobbin style trannys for these high gain circuits instead of Toroids
Wayne uses specially made and shielded toroids that you and I cannot get readily
The typical toroid has wide band noise issues that the others pass over easily for the rest of us.

Regards
David
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