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Power supplies for B1

Posted 9th February 2010 at 07:51 PM by DougL
Updated 28th April 2010 at 06:44 PM by DougL

My brother gave me a Pass B1 board.
Now that he has his working I thought I would look at mine.

I am going to use this space to record all of the links and tricks. Some of the links will be very basic.

http://www.national.com/ds/LM/LM317.pdf

http://optimus.meleeisland.net/downl...s/mc78xxct.pdf

http://www.quasarelectronics.com/kit...c-kit/3060.pdf


http://www.tubecad.com/2007/06/blog0109.htm

http://www.tubecad.com/2007/07/blog0113.htm

http://www.tubecad.com/2008/11/blog0151.htm

http://www.wenzel.com/documents/finesse.html

http://www.borbelyaudio.com/psshunt.asp
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Some progress

Posted 4th February 2010 at 07:15 PM by Bas Horneman (Bas Horneman's diyAudio.com blog)

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LM1876 power amplifier

Posted 3rd February 2010 at 11:09 PM by JozzaG

hi,
im new to this amp building thind and im having difficulty.
ive bought a few parts and im just having difficulty with the power supply, ive got a 240V 50Hz input to 24V AC max 3A output transformer, however it has only 2 leads and is not centre tapped like i orignally planned or was told. its model is the M2158L transformer and i was looking for some help on how to wire it up and use it in my amplifier.
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Rating: 4 votes, 4.75 average.

GB F5 Guide (pcb version 2)

Posted 3rd February 2010 at 01:17 AM by cviller
Updated 14th February 2013 at 07:14 PM by cviller

As promised, I would make a guide to the boards and in particular to the additions I have made to the F5. I decided to do this in the blog, because then you can give me comments which I can use for improving the doc. However I'm not done at all, but I thought it would be nice to give you access to the BOM I have made.

IMPORTANT: Before you start stuffing your boards, you must read the manual/article written by Nelson Pass – available for download on the First Watt website (First Watt: Products: F5).

Detailed guide by Steve and Matt: http://www.diyaudio.com/forums/pass-...mentation.html

PCB
Here is a picture of the pcb.
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There are no more boards available, but you can order F5 boards on the diyAudio store.


Schematics
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Optionality
With the addition of optional extra output mosfets and cascoding, there are...
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B1

Posted 29th January 2010 at 07:58 PM by Cro maniac

I finally gathered some will to deal with my Pass B1 project. I drawed the board in Protel and bought the components at Farnell almost 6 months ago, but never got time/mood/will to assemble it. Wednesday was my day off at work and I had nothing to do at home so I decided it is the Pass B1 day . I printed and made the boards, drilled the holes and lacquered them. Couple of hours later they were ready for soldering the components.
But hey, there is a bag full of 2SK170's that need to be matched prior to soldering ! I managed to get 3 matched pairs and I need only 2. Good enough
My version is the one with Salas regulator with R6 mod so I used the leftovers from matching in supply.
Now, everything is soldered and in place except input coupling 1uF caps and pot that I yet need to buy.

Now when it's nearly completed I don't sleep thinking how should the case for the preamp look like. I would really like to make it from wood.
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Matching BJT's

Posted 27th January 2010 at 08:27 AM by Cro maniac

Yeah, my first blog entry !

I have spent whole day in matching output transistors for poweramp I'm building for a friend.
I found out that Vbe tracks gain pretty good (the transistors with higher gain have proportionally higher Vbe), so I think the painful matching of Vbe at various collector currents is pretty much useless because Vbe spread can be already seen in DC current gain.

If I think of Vbe tracking gain, it is good, because transistor that needs more Vbe will be less opened, but it has higher gain, so collector current will be more equal between devices.
I have 10 pairs of MJ21193 / MJ21194 and plan to use 4 pairs per channel.
Transistors are ordered directly from Onsemi and the NPN's all come from the same batch but PNP's are from 2 different batches and that can be clearly seen from measurements because there is a big mismatch in gain between the 2 batches.

Fortunately, the ones from the same batch are pretty...
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Inductor Evaluation Help

Posted 27th January 2010 at 04:40 AM by audi0

[FONT="Verdana"][SIZE="2"]Over the last couple of years amongst other things, I have been playing around with T amps changing and upgrading components, noting changes etc. When I saw the ‘Inductor Evaluation Help’ thread by ICE_Mag it was of immediate interest to me.
I have read a fair bit about the audible effects of different inductor types used in these amplifiers, some people liking air core and others ferrite core toroids etc. so I registered my interest with the supplier.

It then occurred to me which of my amps (I had three T amps at that stage) would be the guinea pig for my trial; I pondered on this for a while thinking that although all were modified, they are all in a condition where they could be sold if they became surplus to my needs.
I therefore looked on eBay and saw an Hlly amp at the right price, so I bought it.

The inductors arrived, two each of three different sizes (all 10mH) hmmm I thought, how am...
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andy_c is banned?!

Posted 24th January 2010 at 07:50 PM by gootee

Dear diyaudio,

I was shocked and very much saddened, today, when I discovered that andy_c has been banned from diyaudio.com.

I know that Variac and the moderators have a sometimes-difficult job to do, that is necessary and is appreciated, overall. And I have gathered that they felt that they had no choice. But this seems like much too great a loss for this community!

And I cannot seem to find out what actually happened, which leaves me feeling very unsatisfied with the sparse explanations that I did manage to find.

This is a _major_ loss and it needs a major explanation. I believe that that much is owed to all of us, in some sense, especially since I am not aware of anything in andy_c's posting history that hinted that he might ever even be a candidate for banning, or even binning; quite the opposite in my opinion.

And now I can't help but fearfully wonder: Who's next?! AndrewT? Janneman? Bob Cordell? (to...
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Rating: 3 votes, 4.67 average.

Tech note: Balanced lines-1

Posted 13th January 2010 at 05:54 PM by jan.didden
Updated 13th January 2010 at 05:57 PM by jan.didden

Why would one use balanced interconnects, and how can we make them work well?

Balanced lines came about at a time where very long signal lines were coming in use for telephone and later for large audio performance venues. If you use a single screened line for your signal, and the line is long, the ground current through the screen causes a voltage between the ground points of the cable ends. Since the signal send out (and received) is the difference between the voltage on the signal wire and the ground wire, the unwanted signal (noise, hum) is effectively added to the wanted (music) signal. We don’t want that.

The trick is to use TWO signal lines in parallel. You send the signal over the two lines in such a way that the signal you want to transmit is the difference between the signals on these two wires, and then at the receiving end you have an amp that reacts to the difference between the two lines, so your signal at the far end is the difference between...
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CSS bias

Posted 12th January 2010 at 03:32 PM by DougL
Updated 13th January 2010 at 08:52 PM by DougL

I found a great comment in post http://www.diyaudio.com/forums/tubes...3a-driver.html post #10.

Very few details were given, but it caught my imagination.
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