My first (2) DIY amps?

[Mimesis]

So I plan to make a cmoy (2x 9 volt batteries) with tangents step by step, not really thinking of putting many tweaks into it because shortly after I plan to make the a-47

I think i basically have the cmoy design down but when looking at the a-47 instructions provided here http://benfeist.com/a47/images/a47_a..._schematic.pdf i can't seem to figure out what "D1" is on the diagram..
He says to look at tangents parts list, but, D1 in tangents part list is an LED. But looking at the schematic in the pdf, it's clear that the LED and RLED are not D1. So what is D1 i ask?

 

[MisterX]

D1 appears to be a "crowbar diode"

 

[Mimesis]

oh! thanks much, somehow i didn't know that page existed, silly me!

 

[Mimesis]

is that diode needed in the cmoy? on tangents parts list i don't see it included, its labelled d1 on the diagram but d1 on the parts list is an led

edit: oh, that was the meta 42 parts guide that you listed. I supposed thats just his way of labeling and d1 can mean different things for the different circuits on his site?

 

[MisterX]

Quote:

is that diode needed in the cmoy?

What are the chances of you hooking a battery or the batteries up backwards?
If you think the chances are slim or none feel free to omit that diode.

If you like the idea of having reverse polarity protection then the attached schematic may be a better solution.

(the series diode method uses a cheaper diode and will not harm the battery or batteries if you connect them backwards but there is a voltage drop across the diode )

 

[Mimesis]

Thanks for your help and quick responses!

 

[MisterX]

You're welcome.

FWIW there was another 47 amp layout floating around here a few years back but I can not find the thread now....However I did save one of the images.
(might be a little easier to build this one)

 

[seroxatmad]

Hi

Nice layout. Did you use a design prog to get that or a standard gfx package?

John

 

[maxyeah]

misterX,what's your layout design soft? i am seeking for one

 

[MisterX]

Quote:

Originally Posted by seroxatmad /img/forum/go_quote.gif Hi Nice layout. Did you use a design prog to get that or a standard gfx package? John

I did not make that one but I use photoshop for the layouts that I have made.

Example----> http://i23.photobucket.com/albums/b3...de/xfeed-1.png

 

[MisterX]

Quote:

Originally Posted by maxyeah /img/forum/go_quote.gif misterX,what's your layout design soft? i am seeking for one

Try a Google search for "stripboard magic"
If you can't find it send me a PM with your email address and I will send it.

 

[Mimesis]

is there any recommended progression for DIY amps. There just seems to be so many options out there. I know I'm going to build a cmoy to start, then an a-47 (just because it's good for grados apparently.) But i really want to head into higher end desktop amps. It seems that the PPAv2 with bass boost and cross feed would be the next step (at least in the selection of amp instructions on tangents page.) What would be after that? M^3? Is there any list describing average cost, quality and complexity of the DIY amps. I don't want to make one and then 'progress' to a more complex amp that is actually a downgrade in performance.

 

[franky_s]

Quote:

Originally Posted by Mimesis /img/forum/go_quote.gif Is there any list describing average cost, quality and complexity of the DIY amps. I don't want to make one and then 'progress' to a more complex amp that is actually a downgrade in performance.

Perhaps this may help:
HeadWize: DIY Workshop > Current DIY Headphone Amp Offerings

 

[Mimesis]

woohooo! Ordered the majority of my parts from digikey and picked up tools and other stuff from the source!

The cmoy is really going to be my introduction to DIY in general, so I'm going to go directly with tangents design.

What I would really like advice on though, is the approach to the a - 47 i should take. I will most likely just be using it on my desktop until i build a nicer amp with my sr225's

Power will be from the wall, wallwart i suppose.
I have a few questions actually, some which will just help me build it, and some that hopefully will help me understand it.

Some questions I have:
1. Why does this 2 opamp design provide more current?

2.The TLE2426CLP and BUF634 are part of the power supply and are used to provide stable voltage?

I think i have read that resistors limit the current that goes through a circuit.

3. Hows does adjusting the gain affect the current? (I'm just curious since im trying to provide lots of current for my grados) and

4.which gain should i be using?

5.What kind of case would be good for the a47 for use solely with wallwart. and radioshack pcb (cut in half)

6. Is there any place to pick up alps RK097 and TLE2426CLP that takes payment via credit card (canadian) rather than just straight paypal?

7. Is r5 in this circuit (http://benfeist.com/a47/images/a47_a..._schematic.pdf) just there to reduce noise like in the cmoy? If so does that mean it's optional in this amp as well?

 

[heatmizer]

Take a look at veecad for doing breadboard layout. it has a free and pay version. can take a netlist from eagle