525 build thread

peter purpose

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Let's get started with a BOM

http://www.twin-x.com/groupdiy/albums/userpics/525bomupdt3~0.pdf updated again.

and schematic...

525Cschem21sm.jpg
 

okgb

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Nice Work Peter , thanks for your time on that

Of course it would be good to order all the parts and be
ready for when the boards come !
 

Rob Flinn

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Peter (me ol' fruit)

Any chance of having this file in excel spreadsheet format ?? Make it a bit easy when trying to work out the cost of parts etc.
 

peter purpose

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Give me three or four weeks :green:

http://www.twin-x.com/groupdiy/albums/userpics/525BOM.xls
 

rafafredd

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Hey Peter, are you also using a 2520 for the input opamp? These makes for 4 2520s for each unit. Serious job, if all opamps are DIY.
 

Ptownkid

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[quote author="rafafredd"]Hey Peter, are you also using a 2520 for the input opamp? These makes for 4 2520s for each unit. Serious job, if all opamps are DIY.[/quote]

I think it's 3 per 525...
 

peter purpose

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Rafa.. copy of a UREI 5 transistor op amp on the front end. Pcb included in the set.

Rob.. No. You're on your own.
 

gyraf

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For A3, the sidechain-transformer driver, it'd probably be enough to use a standard opamp with a couple of BD139/140 power booster transistors.

Question: Why not a simple 10K:10K input transformer instead of additional opamp stuff?

Jakob E.
 

peter purpose

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[quote author="gyraf"]
Question: Why not a simple 10K:10K input transformer instead of additional opamp stuff?

Jakob E.[/quote]

Room on the board Jakob.
normal_OL.jpg


Large.. http://www.twin-x.com/groupdiy/albums/userpics/OL.jpg
 

Greg

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Been studying this schem getting ready for the build, and I don't understand what Q5 is doing. Can someone explain?

At first I didn't understand the bias of Q1, but I read the datasheet and it cleared that up.
 

rafafredd

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Rafa.. copy of a UREI 5 transistor op amp on the front end. Pcb included in the set.

Nice. I like that simple opamp, it´s almost the same as the Quad8 AM4. Sounds good, and is very simple.
 

mnats

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[quote author="Greg"]Been studying this schem getting ready for the build, and I don't understand what Q5 is doing. Can someone explain?[/quote]
At first glance it looks like it is adding an AC signal to the gate to reduce distortion.
 

edanderson

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since peter started his project, i've been working on getting some ap2623 type transformers made. unfortunately, the first supplier i was working with backed out after a few weeks, so now i am a bit behind.

i don't want to discourage anyone from going ahead and buying transformers. but i should have something good available in a few weeks. until then, please do not contact me. as soon as they are available i will post to this thread and post to the black market.

ed
 
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