[jeftsang]

hey everybody, you may have noticed my recent frequency of posts around here. First I thought I wanted an A47 amp, then I thought about a Cmoy to learn on, now I think I've settled on the RA-1 clone. I've got a couple questions about building it since it will be my absolute first project

first I'd like to double check and see if I have the right parts list

My inteded parts list includes:
100K ohm pot (hopefully an alps blue velvet!)
100K ohm 1/4 watt metal film resistors.
121K ohm 1/4 watt metal film resistors
464k ohm 1/4 watt metal film resistors.
Are there any reccomendations for resistors or are they all pretty much the same.

5 micro farad capacitor for input(thinking solen, black gate, or auricap, worth the money?)
.12 micro farad capacitor for the power supply I believe. Doesn't matter what I use here does it?

As far as the JR4645, 4556 I'm a little bit worried about where I'm going to source this sucker. Anybody have any luck? I might try an IC socket and opamp roll later on, does anybody have a good recommendation for an OPAMP to use in the meantime while I source an original JR4645, 4556?

I know there are a couple of other people are are interested or are currently in the process of building an RA-1 clone. I'd be very interested in your feedback. Thanks a lot guys.

 

[Gariver]

Mouser.com has the New Japan Radio opamp for sale!

NJM4556AD dual opamp...

http://www.mouser.com/index.cfm?hand...oductid=375463

 

[jeftsang]

Can I plug this into the circuit just as I would the 4645? Or is it meant to be used in a dual opamp circuit design such as the A47?

 

[Gariver]

Here's the NJM4556's datasheet. That New Japan Radio pdf file shows you how to make all the connections for that dual opamp.

http://www.njr.co.jp/pdf/ae/ae04051.pdf

Please note: All the connections of the NJM4556 are the same as the popular OPA2134 dual opamp.

Good luck!

 

[jeftsang]

Great, thanks a lot garriver!

I'm getting parts together from mouser and there is such a selection I'm having trouble deciding which is going to be best.

I settled on Vishay metallized polyproylene caps for the inputs but should I get 100, 200, or 400 wvdc, also what does this mean?

I was going to buy the 100WVDC 5uf
part number 75-735P505X9100L is this correct?

for the ps caps I was going to get part number
75-225P100V0.12 vishay polyester capacitors.

One thing about resistors I couldn't find any dale vishay's for 464k ohm but I did find 4.64k ohm and 464 ohm. Are these the same? Can I substitute them?

Thanks for reading all this newbie junk, I'd appreciate any help you can offer. This is my very first project, I'm really excited!

 

[Hirsch]

Quote:

Originally posted by jeftsang One thing about resistors I couldn't find any dale vishay's for 464k ohm but I did find 4.64k ohm and 464 ohm. Are these the same? Can I substitute them?

K is shorthand for x 1000

A 464K resistor is 464,000 ohms. A 4.64 or 464 ohm resistor will not substitute for it. You would need 1000 464 ohm resistors in series to substitute the correct value.

 

[jeftsang]

thanks, didn't think so

looks like I'll have to use another brand.

 

[tangent]

Quote:

I settled on Vishay metallized polyproylene caps for the inputs but should I get 100, 200, or 400 wvdc, also what does this mean?

WVDC = Working Voltage, Direct Current. So, 100 WVDC means that the highest voltage that it will work for without any risk of damage is 100VDC, which is equivalent to about 35VAC RMS for sinusoidal signals going + and - around a ground. I.e., music. Thus, 100WVDC is plenty high for music, since your source certainly puts out 2VAC RMS or less at peak, and typically more like 0.5 to 1V. Buying caps rated for higher voltages than you need is a waste if money and space, and may even give worse performance, since ESR often goes up as voltage tolerance goes up.

That said, don't worry about trying to find film caps of even lower value just to make it lower. A 100V Vishay-Sprague Orange Drop 715P is probably better than a 50V Panasonic ECQP, despite the fact that both are polypropylene film and foil.

Metallized caps specify the value in working voltage terms because they "self-heal" if you pass too much voltage through them. I.e., they don't get completely damaged if they get a voltage spike. Contrast film and foil caps or non-film types (ceramics, tants, lytics...), which stop working if you zap them, so the maximum working voltage is the same as the absolute maximum voltage.

 

[Arzela]

Mouser has a hunded or so 464k 1/4 watt
vishay's at the momment (five day wait
though). Better hurry....

http://www.mouser.com//index.cfm?han...oductid=383847

 

[jeftsang]

thanks a lot for the info guys. Unfortunately I put my order in at mouser already, I'll call them tomorrow and see if I can change the cheapie xicon resistors I bought to some vishays

I can't wait to get the parts. I'm going to be building a cmoy in a little bit as well since my brother has got the parts already, just never found the time/motivation to put it together. If I ever succeed in these two projects I know you guys would love another opinion in the great ra-1 cmoy debate

I'm trying to learn as much about electronics and circuits as possible so that I can contribute a little more and have a better understanding of future mods.