generic components? - Page 2 - diyAudio
Go Back   Home > Forums > Amplifiers > Chip Amps

Chip Amps Amplifiers based on integrated circuits

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 7th October 2012, 01:11 PM   #11
frank1 is offline frank1  United Kingdom
diyAudio Member
 
Join Date: Apr 2006
Location: Devon UK
Quote:
Originally Posted by madisonears View Post
Some resistors do sound a little smoother (carbon film), some a little brighter (metal film), some a bit more open or accurate (bulk metal foil).
Useful post... apart from this!
Evidence?

Frank
  Reply With Quote
Old 7th October 2012, 10:45 PM   #12
diyAudio Member
 
Join Date: Sep 2007
Frank,

Thanks for the compliment.

I wrote that these are my opinions, based on my experience.

Please don't wreck this thread by starting that silly argument. If you disagree, say so. Otherwise, please drop it.

In other words, I do not have any evidence, if by that you mean purely objective testing or measurements. Let the builder experiment and decide for himself.

To the original poster: my amps use the 3886 chip. My speakers dip to 2.5 ohms at 5k, otherwise pretty close to 4 ohms. My transformers are 21v. I have never engaged chip protection and the chips get barely warm at decent volume.

You can always change transformers later, if necessary. I would suggest you buy and build everything in identical pairs if you want monoblocks. Two amps with different power supplies and/or different layouts probably will not produce a good stereo image. You're leaning toward failure before you even start.

Peace,
Tom E
  Reply With Quote
Old 8th October 2012, 12:53 AM   #13
ChrisA is offline ChrisA  United States
diyAudio Member
 
Join Date: Jan 2008
Quote:
Originally Posted by imaginarytime View Post
...
I'm assuming that for some things (maybe over-specified resistors?) manufacturer can't matter, maybe I'm wrong.

I'm interested to know where "generic" components might be a problem.
Good quality is all you need, avoid the really cheap no-name surplus stuff. There is no need at all for the "exotic" $10 passive parts that are filled with genuine snake oil. If you buy from Mouser, digikey and the like and stay away from eBay you will be fine. The US based distributers will have manufactures' data sheets linked from the product listing. Read those and you will not be surprised with what you get.

Electrolytic caps do vary. They are not all alike and you can see this in the data sheets with specs like the number of hours of life, allowed ripple current and so on. Film type coupling caps are all very close as are resisters.

Some people claim to be able to hear the difference between exotic $50 caps and generic poly film caps but I've never seen this confirmed in a blind test. So don't over spend, unless your goal is bragging rights to the most expensive chip amp.

You are right about shipping costs. It is cost effective to buy parts for the next four or five projects all at once. But it is also expensive to buy parts you will never use.
  Reply With Quote
Old 8th October 2012, 01:04 AM   #14
ChrisA is offline ChrisA  United States
diyAudio Member
 
Join Date: Jan 2008
Quote:
Originally Posted by frank1 View Post
Useful post... apart from this!
Evidence?

Frank
Yes. I've looked for blind test to back this up and don't see any. By "blind" I mean a person who can tell you what kind of resister is inside the amp just by listening without having to open up the amp and look. If you can't know, except by looking inside I say it hardly matters.

That said there is good reason to suspect resisters are different and they have measurable differences too. Carbon resisters change their resistance based on the voltage across them. In other words they do NOT follow ohm's law. This happens at the "couple percent" level and is subtle but a real. The effect on the sound is "compression" or reduction in dynamic range. Some call this "smoother" sound. Carbon resisters also have high "noise" (sounds like hiss) and this noise gets higher with higher resistance values. The compression effect is very tiny if there is not much voltage across the resister so this matters mostly in tube amps that use power supply rails well over 200 volts. There is zero difference if you are using a 9V battery or a even 24V rail. but if you have a 100V peak to peak audio signal inside you preamp (as some tube amps do) to effect is really there.

Many guitar amp builders will use Carbon resisters in certain places, like for plate load resisters and it does slightly matter but adds "hiss" so they will use metal resistrs in other places.

The metal resisters do have the lowest noise.

One other this is the size. You can use a 1/4W or a 1W. the larger 1W resister will be more quiet as it runs at a lower temperature. If a resister is burning up much power, buy one 4X over size so it runs cool. Heat actually creates noise.

Last edited by ChrisA; 8th October 2012 at 01:09 AM.
  Reply With Quote
Old 8th October 2012, 03:39 AM   #15
diyAudio Member
 
Join Date: Oct 2012
Thanks again guys.

This most recent point on resistors seems to be an unambiguous claim that over-rated resistors are dominate other alternatives. Other than trying to make the smallest chipamp ever, I'm not sure I see the downsize of overrated resistors, taking make quality as equal of course. This seems like a pretty big deal and well argued.

I don't have the prerequisites to make the most expensive chipamp ever. I'm going to tune up my soldering for a little while and then start by building the audiosector kit with 25V. I'm going to do it by the book and see how it goes.

I think it is usually best to try to cook the recipe first.

Simultaneously, I'm sourcing supplies for another.

I really don't like the idea of having to piece my orders together from a bunch of places.

Mouser's shipping over $100.00 is pretty reasonable, but if you want to spend less than a c-note it is quite unreasonable. We all know it is easy to get to $100.00, so that's not really too bad.

I'd love to be able to buy everything in one place. Where do you guys get rca and speaker connections and what about the wire from the connections to the chip? That beautiful hardware from cardas is nice and all, but the website isn't even clear on how to buy it, much less how much it costs.

Seems to me it is important to identify which links are the ones where the "only as strong as weakest" proverb is binding. That's sort of what this thread is all about. Where is it crucial to spend the money and where is it useful to spend the time and energy to do it very right. That point about the power cord above is well taken. It doesn't cost a fortune to use something other than the ubiquitous 3 prong cord. I probably have 10 generic plugs from foxconn in the basement. It may not be a game changer, but it is easy and kind of inexpensive to attend to a detail like that which did not seem obvious to me until I read it.

In that giant audiosector thread PD mentions something about gold plated copper wires running from the rca connectors. That's no doubt bad ***, and it isn't like I'd rather rip open a phone wire, but is there a happy (upper) medium before having a custom alloy smelted?
  Reply With Quote
Old 8th October 2012, 03:54 AM   #16
diyAudio Member
 
Join Date: Oct 2012
Tom, by the way. I'm not building a dual monoblock with two different transformers. That seems like it would be a little crazy and I don't even understand why. Maybe someone should try it to find out, but it won't be me. I'm building two totally separate chipamps.
  Reply With Quote
Old 8th October 2012, 04:00 AM   #17
ChrisA is offline ChrisA  United States
diyAudio Member
 
Join Date: Jan 2008
Quote:
Originally Posted by imaginarytime View Post
Thanks again guys.

This most recent point on resistors seems to be an unambiguous claim that over-rated resistors are dominate other alternatives. Other than trying to make the smallest chipamp ever, I'm not sure I see the downsize of overrated resistors, taking make quality as equal of course. This seems like a pretty big deal and well argued.

I don't have the prerequisites to make the most expensive chipamp ever. I'm going to tune up my soldering for a little while and then start by building the audiosector kit with 25V. I'm going to do it by the book and see how it goes.

I think it is usually best to try to cook the recipe first.

Simultaneously, I'm sourcing supplies for another.

I really don't like the idea of having to piece my orders together from a bunch of places.

Mouser's shipping over $100.00 is pretty reasonable, but if you want to spend less than a c-note it is quite unreasonable. We all know it is easy to get to $100.00, so that's not really too bad.

I'd love to be able to buy everything in one place. Where do you guys get rca and speaker connections and what about the wire from the connections to the chip? That beautiful hardware from cardas is nice and all, but the website isn't even clear on how to buy it, much less how much it costs.

Seems to me it is important to identify which links are the ones where the "only as strong as weakest" proverb is binding. That's sort of what this thread is all about. Where is it crucial to spend the money and where is it useful to spend the time and energy to do it very right. That point about the power cord above is well taken. It doesn't cost a fortune to use something other than the ubiquitous 3 prong cord. I probably have 10 generic plugs from foxconn in the basement. It may not be a game changer, but it is easy and kind of inexpensive to attend to a detail like that which did not seem obvious to me until I read it.

In that giant audiosector thread PD mentions something about gold plated copper wires running from the rca connectors. That's no doubt bad ***, and it isn't like I'd rather rip open a phone wire, but is there a happy (upper) medium before having a custom alloy smelted?
One topic at a time:

1) I think Digikey can ship small orders cheap. They can use first class mail for some items.

2) I buy many parts from Futurlec. They are an Australian company that ships from Asia. They sell quite a bit of what you need

3) What is the "weak link". My opinion it is the power supply. You need a good transformer, hopefuly 4X over sized and some decent filter caps and (importance) a good physical design that extends all the way to the power/ground pins on the chip. This is not Rocket Science. BTW "Antek" makes good toroid transformers and will ship as many as will fit in a Flat Rate box for the price of the box. They have good detailed specs with test results of each transformer on their web site.

4) Don't even think of using some special power cord. It will only make you look gullible. Ok if you do want a fancy cord, you may as well replace the wire in the house and on the utility poles too. Seriously, the power suly takes care of all this.

One thing you CAN do is replace the IEC connector with an "inlet filter" these things really do work and they are cheap and keep RF out.
Welcome to Delta Electronics, Inc. - Components

5) Why even use RCA connectors? What are you going to plug into the amp? Is it RCA? If you do use RCA, just have a good reason. There are other connectors. What to use depends on the source.

Wire from the input jack does matter. The best is shielded. I use RG-174 (googol wil find it for you) but any shielded coax cable is good. Yo can cut up some old RCA cables and use that, any junk RCA audio cable is good. The matal inside does not matter but the shield does. It keep noise out.

I like "speakon" speaker connectors. They outperform just abot every other type and don't cost much. And they look really cool.
  Reply With Quote
Old 8th October 2012, 04:26 AM   #18
diyAudio Member
 
Join Date: Oct 2012
I was planning on Avel. (one 250 the other 300 for separate builds.) Are Antek brand really much better for chipamps?

On power cords, I agree that spending extra money on a plug is nothing anyone would want to mention in polite company. I was thinking the idea was to buy decent and appropriate 3-wire cord and just screw on connections and not talk about it. Better than plastic crap from foxconn. Kind of like H. Lectors '...with your good bag and your cheap shoes...' argument.

RCA or whatever, I agree that the tool is the job. My question was trying to get at the connectors and I don't know all the proper names of stuff. Your suggestion is just what I need, scale and the name and terminology so I know what to read about.

Last edited by imaginarytime; 8th October 2012 at 04:40 AM.
  Reply With Quote
Old 8th October 2012, 05:01 AM   #19
diyAudio Member
 
Join Date: Oct 2012
I really like the look of what Antek is doing.
  Reply With Quote
Old 8th October 2012, 06:06 AM   #20
kevinkr is offline kevinkr  United States
diyAudio Moderator
 
kevinkr's Avatar
 
Join Date: Sep 2004
Location: Boston, Massachusetts
Blog Entries: 6
I've purchased a number of Antek transformers in recent years and they are an absolute bargain compared to most of the competition. They are also generally conservatively rated and quiet in operation which is important for audio applications.
__________________
"Extraordinary claims require extraordinary evidence." - Carl Sagan
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Looking for (Generic) Preamp Troubleshooting Advice stellavox Solid State 2 19th December 2009 07:13 PM
Generic Switching PS nukaidee Parts 1 12th April 2009 08:06 AM
Generic Sub Crossover Suggestions? Dominick22 Subwoofers 9 16th October 2006 12:38 PM
Generic Open Chassis Design ... TVP Solid State 21 5th September 2005 03:01 AM
Generic Open Chassis Design ... TVP Class D 0 12th January 2005 04:21 PM


New To Site? Need Help?

All times are GMT. The time now is 01:27 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2