# yay, now I can get help making my amp



## Neruda

I'm going to build a 47 amp, will I need four opamps? (By the way, I plan to use OPA2604's)

 I'll post more questions as I remember them.


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## skippy

4 opamps or 2 dual opamps


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## Apheared

what skip said (just blurtin "I'm here")


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## hongda

Apheared: why did you call the 47 a dual output amp?


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## Neruda

damn, this is getting spendy! I've already wasted $40 on amp stuff. This thing had better sound good!

 Hey, can someone explain resistor color code to me?


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## Apheared

$50-80 is average, dude. that's what it costs, sorry. You can get by cheaper of course; but if you're starting from scratch, need tools, have no components, and have to mail order from multiple places... $50 is about the cheapest you can pull it off.

 hongda, dual output as in parallel output... the thing functions fine with just one, it's called a cmoy pocket amp! It just functions better with two. (specially for low-ohm things like Grados) NOT as in two individual outputs.


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## jude

Quote:


 _Originally posted by Neruda _
*damn, this is getting spendy! I've already wasted $40 on amp stuff. This thing had better sound good!

 Hey, can someone explain resistor color code to me? * 
 

Neruda,

 JMT built several amps for me, and the cost was always between $50 and $55 or thereabouts. Of course, if someone's buidling me an amp, I always make sure to throw in a little something extra.


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## Neruda

I know apheared, I just wish I had enough money to get everything. well, it's my own damn fault, I wasted the last of my money on a CD 
	

	
	
		
		

		
		
	


	




. Looks like the big project is gunna be postponed until I can pick up another $20, which shouldn't take too long. (damn, I need a job.)


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## Daniel Pumphrey

Neruda, 
 Apheared's amp has parallel output opamps. Don't trust the resistor color codes on the RS metal film resistors. Email me if you need help with this. You really ned to check them with a meter. 
 My first step was to layout the parts locations. I think these amps are easier to make with dual opamps. Power supply wiring is easier with duals. 
 Dan


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## tooler

Yeah, glad to see this forum is here to hold us over for two weeks!


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## AndrewB

Mnemonic\color\value\Multiplier

 Bad-----Black---- 0--------.0
 Boys ---Brown----1---------0
 Rape----Red------2--------00
 Our-----Orange---3-------000
 Young--Yellow----4-------0000
 Girls----Green---5--------00000
 But-----Blue-----6-------000000
 Violet --Violet----7------0000000
 Gives---Grey------8-----00000000
 Willingly--White---9----000000000


 Precision resistors have a 5th ring thus a brown\black\black\brown\brown resistor would be :1.000 ohms


 If I made an error please forgive me, this is off the top of my head. I can look it up later. 

 Peace,
 Andrew


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## Neruda

I should probably just get a multimeter, I've been checking a few resistors and I think I'm getting it wrong. Doesn't matter though, I can't start my amp for a bit longer.


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## aos

There's usually also one additional ring, to mark the resistor's tolerance. For example, red is 2%, brown is 1%. It's unlikely you'll get better than that, and if you get worse it's probably a carbon film resistor, not a metal film one. This precision ring is usually separated from the others, on the very edge of resistor, although it's sometimes hard to judge.

 Very high quality resistors usually have numeric markings for both value and tolerance.


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## cmoy

Get a multimeter! Do not use the resistor codes. They are confusing and hard to see clearly. Besides a good multimeter costs around $20 and is a necessity for troubleshooting.


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## skippy

good to see you chu!


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## Neruda

thanks for the advice chu, I'll go ahead and do that.


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## jonpile

Hey Neruda,

 If you haven't picked one up yet, there's a pretty good, cheap ($19) digital multi-meter at Circuit Specialists:

http://shop.store.yahoo.com/webtronics/index.html

 I haven't seen a better deal so far.

 -jP


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## templeboy

Now I can get help for the van Waarde amp. Before purchasing parts, I already invested $ in power drills, hole punch... I can locate almost all the parts and some how parts along cost more than $100. We're talking about generic parts from Digikey and alike here. Along w/ the investment in tools, it better sounds good.


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## JerryNA

Seems like old home week
	

	
	
		
		

		
		
	


	




 Glad to see the gang found a spot for now


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## Budgie

Neruda, if you do get a multimeter, you will find that the resistors are only somewhat close to the value that they are marked at. Every resistor will be different from the value, due to inaccuracies in manufacturing. A multimeter will help you match the resistors for the best performance from your amp. And they can help troubleshoot if you have problems too. Have fun!


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## Neruda

thanks budgie, I will get the multimeter as soon as I can. I just got my new case, so now I get to sit here and imagine what my finished amp will look like. But that's all for now


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