Hopefully I can contribute soon. I am starting a Pearl 2 build - going with the dual Par Metal chassis like 6L6. Just sent the back panels to Front Panel Express. Need to finish my F5 first. Busy buying a lot of records as well!
I have my Pearl 1 in the same chassis. Too bad it turned purple.
How does the sound compare to the 1? I love the 1 and if the 2 is any better I think I have my next project.
How does the sound compare to the 1? I love the 1 and if the 2 is any better I think I have my next project.
Got a package today from Front Panel Express. Ready to start the the Pearl 2. Following 6L6's lead and using the Par-metal 20-12083B. I forget to include the drill hole for the turntable ground lug but I am sure I can handle that with my drill press. My Rega RP1 does not actually have a ground but will include for the inevitable upgrade. 🙄The gummy bears were a nice touch.
I will work on the PSU first and not even think about stuffing the amp board until it is absolutely perfect.😀.
I will work on the PSU first and not even think about stuffing the amp board until it is absolutely perfect.😀.
Attachments
wow, that's better than having to do al the drilling and sawing yourself. Maybe it's better to post all follow-up in the main Pearl 2 thread. I will do that too. I finished the PSU, figured out the board layout and plan to start building one channel this weekend.
What is the maximum diameter and lead spacing for the 10KuF electrolytics (C1, C26)? Would a snap-in capacitor fit into the holes? Thanks.
Yes, the Pearl Two board is drilled for snap-in caps for that location. There's a 24mm circle on the silkscreen there, and the lead spacing is 10mm I think.
Question about stuffing the Pearl Two boards - there's an unmarked solder pad on the ground plane between C4, C6 and C12. What's it for? I was wondering if maybe I need do solder a jumper through there to link the front and back planes?
Mr. dB - That's the center of the ground potential -- connect it to the TT ground lug.
You can kind of see it in this photo -
You can kind of see it in this photo -
I forgot about this 'awesome' drawing I did in the different Pearl 2 thread -
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.)
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 forgot about this 'awesome' drawing I did in the different Pearl 2 thread -
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?
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.
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
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
That transformer looks excellent. It will be perfect for the project.
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.
That is always a good idea, use it! 🙂
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! 🙂 🙂 🙂
Wonderful to meet you as well! We are all very glad you are here and building something in this wonderful hobby!
😀
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?
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?
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
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