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Old 31st January 2011, 06:42 PM   #11
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okay.. a very big thanks about the heads up on additional voltage.

it would be a real heart breaker if i bought an amp kit and ruined it on the first day because there was excess voltage.

i have been slowly sticking my nose into electronics design for a few years now.
if you have a look at my join date to this forum, you will see what i mean.

i dont have my heart set on hooking up an amplifier that can run my 12w7 at full power.
but i would like to start playing with diy amplifiers.
it seems like i could use one for my rear surround speakers and if all goes well, i would maybe build some amps for my car radio.

it may be the only times i use the amps.. but if my experience is good, i would show other people that an alternative exists when they come to a forum looking for suggestions.

maybe some day i will go on to build a reasonable amplifier to power some subwoofers in my home theater.
or maybe i will start to bi-amplify my speakers.
money is one thing.. having kits with sound quality is also needed.

i wouldnt mind trying to learn some of the ways to make the amplifier sound better.
so far i have started with transistor quality.
i might move on to capacitors and other components of the circuit board.

i'm thinking about going to college for electronics as my second college degree.
therefore, the further ahead i get when viewing with interest.. the more i learn if i am willing to go to college and have a career as an electronics repair person.

i started to get frustrated when the science teachers began talking about diodes.
it seems like i have been looking for other components that are easy to understand, and if that component list gets high enough.. all the stress from being confused about a diode will go away.

i am slowly starting to build a virtual electronics project.. and one day i hope to take the virtual project and turn it into a hands on experience.
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Old 31st January 2011, 06:45 PM   #12
lgreen is offline lgreen  United States
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It seems to me that you think you can DIY this and save some money. Lets take a look at that.

What you are proposing to do will cost a lot of money. Say $100 for a large transformer, $10 for a bridge rectifier, and lots more for capacitors, another $100 easy.

You are at $200 just for the power supply not counting the AC inlet, connections and cables. All for something temporary. And I estimated way way low.

And given what you have said so far you may just hurt yourself if you try it now. I would advise you read up on power supplies and do not attempt this without in-person help from someone who knows what they are doing.

A lot of people who are new at DIYing start out by trying to build a 200W, 500W or 1000W amp and find out that you have to start with like a 30W amp to get going, and move up slowly. Power supplies and amps over 100W are very complicated and you have to be pretty experienced to get them working. You just cannot add more stuff to make it more powerful (wish you could).

So given what you are saying it seems to me that you are on an impossible task with your high power supply to feed a car amp (or to build a powerful amp).

I think by posting and reading here you are learning just how complicated this stuff can be- its not a very good answer to your questions but it is reality. At least you are learning.
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Last edited by lgreen; 31st January 2011 at 06:57 PM.
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Old 31st January 2011, 07:13 PM   #13
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what did i say specifically that implied i 'think' i could do it?
because i recall stating that there are other things in question that need to be addressed so that i dont have an unexpected problem.

my question about choosing capacitors so that the voltage doesnt raise further hasnt been answered.
and i am okay with that.
i realize that if going to college and getting a degree teaches you something, selecting the appropriate values for capacitors is one such *benefit*

you are degrading my desire to seek college.
if you would have read the insight of my posts, you would be able to come to the safe conclusion that i have not been fully addressed.

and this may be a policy of the website.
i realize that it is irresponsible to teach people very basic principles without some kind of warning.
a lot can happen.
house fires or electricution being the top two on my list.

as far as i'm concerned.. i asked if the virtual proceeding in my head was correct and that was answered.
to that note, i was also informed about unexpected changes to the voltage.. as well as shortcomings to the current after being transformed/filtered.
i have taken that as a precaution and not only have i realized there are other obstacles, i have also mentioned some of the obstacles and provided statement that i dont know how to resolve those obstacles.

okay .. alright .. enough

i cannot afford to purchase a single component in the chain.
and if i could, i would only be able to go as far as logic would allow.
that would be purchasing a transformer and rectifier (measure the results) and trying to purchase some capacitors to filter the voltage.
playing around with the filter bank would be as far as i could go.

but the benefit of doing something like this myself is the given right that i can pick higher quality components to have a high quality result.
i havent even begun to build and evaluate the sound quality to compare what i built and the cost of what i built, compared with something that is already built for me and the sound quality that it provides.

i'd like to note that just because i would eventually move the amp and speaker to the car.. that doesnt mean the power supply cant be used with another amp.
i am seeing some amplifiers that have better specifications than a lot of the home theater receivers.
i dont want to argue about real world results because i know the world has its variables and that the method used to obtain the specifications might be different or the specifications listed are simply not true.

designing different filter banks might be a good way to learn capacitor characteristics.
but from what i have gathered here, i dont have the knowledge to specify charge values or voltage values.
i know that if i want guaranteed safety, i would need to take a college course.
and if i dont want to waste a bunch of money trying to learn the correct values the hard way.. again, i would need to take a college course.

i do appreciate your warning, as you should be able to see obviously.
there is no telling if a person is trying to build something that might deal with voltages that are life threatening.

you now know where i stand.. but you should have been able to gather the standpoint from previous posts.

i wish you all a stress free time with your repairs.
and i hope to see some of your repairs on sale so people can save some money
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Old 1st February 2011, 09:08 AM   #14
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Quote:
Originally Posted by anwaypasible View Post
i got the principle.. and building a power supply is complex, so of course i have already ran into other questions.

then there is talk about inefficiency and also unexpected additions to the voltage.
i think the unexpected additions to the voltage are what is really going to help when i decide to purchase an amplifier kit off ebay.
i dont want the voltage to go over the specified range.
no sense in building something only to connect a couple wires and have it break.

i suppose while i am learning, i should eventually find out why 1,000 watts takes a huge transformer for a car audio amp.. but a home audio amp can run 1,000 watts.
i am already starting to think about bypassing the transformer on the amplifier and feeding it the proper voltage.
and i understand that the parts inside might be low voltage but high current.
whereas the home amplifiers might have parts that are high voltage which makes it easier to find a reasonable transformer.

i have searched the forums on a few different accounts.
people are talking about having very high voltages on the 'rails'
and that has given me a path to investigate.
something along the lines of feeding the transistors the voltage they need from an alternative power source and bypassing the amplifiers original power input entirely.

anyways.. i am not numb to possible problems.
there are questions i have asked in the post above this one.
Be careful of Home Hi-Fi specifications.

1000W is not always what it says it is.

1000W True RMS is an enormous amount of power and will require an equally MASSIVE power supply.

Some manufactures use PMPO (Peak Music Power Output). 1000W PMPO may only equate to 10W RMS. PMPO is an inexact science as it purely equates to the ABSOLUTE maximum that the amplifier may produce for a fraction of a section before it destroys itself.

Computer speaker manufacturers are probably the most guilty of the henious crime of quoting enormous PMPOs for speakers that contain small IC amplifiers.
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Old 1st February 2011, 10:26 AM   #15
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Quote:
Originally Posted by Andy5112405 View Post
Be careful of Home Hi-Fi specifications.

1000W is not always what it says it is.

1000W True RMS is an enormous amount of power and will require an equally MASSIVE power supply.

Some manufactures use PMPO (Peak Music Power Output). 1000W PMPO may only equate to 10W RMS. PMPO is an inexact science as it purely equates to the ABSOLUTE maximum that the amplifier may produce for a fraction of a section before it destroys itself.

Computer speaker manufacturers are probably the most guilty of the henious crime of quoting enormous PMPOs for speakers that contain small IC amplifiers.
yea..
i let myself soak in inception.
ppo / pmpo has been something i have come to realize as well as heard spoken about.
there are limbs on those components, and there are options to configure those limbs by either connection or disconnection.
how those limbs stack up amount to results that fill current at different requests.
thats why you pay a premium to have all those limbs coordinated perfectly. but even then, the selection of components might have been junk at the get go.

you request a sine sweep and request that each frequency has the same amount of current.
i'd tell you that you havent considered phase changes and will be able to make that amp look perfect in a weak response test.

real amps play the entire sine sweep with the same amplitude.
and they maintain that current for all frequencies of all phases from 0 - 360 degrees.

lets say 0hz - 30khz
30,000 possible frequencies * 360 degrees of phase each = 10,800,000 electrical requests compensated and calibrated.

i dont know how those cheap amplifiers are calibrated.. but i think the components are 'ringing' or 'resonating' to get those high wattage numbers.
it all depends on how big the ratio of peak to average is.
and it also depends on how often (if) those peaks are absolute maximums or relative highest gain.

because having absolute maximums with a high ratio will make the amp sound like its hot and burning at portions of the frequency range.
and with other frequencies suffering (or being different) it makes the final result obnoxious and undesirable.
you might want to use crossovers to use the amplifier at those high amplitude frequencies.. but if you dont feed the amplifier the full frequency range, those high amplitudes might change or otherwise become dull.

having relative highest gain means that you will have less absolute maximums and more generalized current across the frequency range.
the result sounds like the amplifier is working accordingly and you arent listening to components glow.

obviously there are huge gaps in amplitude with phase changes.
and i think if those phase changes were compensated for.. any flea market amp would show its true colors
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Old 11th February 2011, 02:42 AM   #16
niko084 is offline niko084  United States
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Just curious here, congrats on considering the dyi route first of all.

But, you said you had ground loop issues on your old car amp...
What make/model was it?

Yes, even when people get to read those cool certified numbers on car amps they are tested on perfect sine power supplies that have way more power to supply than the amps could dream of consuming. For us of the louder mobile audio genre this makes it a hard game considering what we have to work with.

I maybe able to help you out with your ground issues, or even possibly power issues if you have a solid amplifier and are just failing to get it good power.

Lastly, any "PRO AMP *not DJ AMP*" that is stable at 2ohms will be fine at 3ohms. You can find a plethora of pro mono amps that are stable to 1ohm. ..
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Old 13th February 2011, 03:16 AM   #17
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the amp that had the bad power supply was a hifonics xx chaos.
and the amp that allowed the noise to bleed through was a precision power a800/2

i gave the hifonics away since i dont know which toroid to replace it with.
i dont have the knowledge to determine how many volts the rest of the amp wants.
besides.. i couldnt find any toroids of that size to even begin replacing the step-up coil.

the whole project has been dismantled and better left alone now that the pieces of the puzzle are missing.

i'll give it another go when i can afford to buy the pieces.
except this time around i am going for a mix of fidelity rather than simply upgrading the power for added decibels.

i'd really like to get on the project though because driving the stock speakers isnt loud enough.
i suppose its a problem of efficiency.
but i'd rather replace/upgrade my broken calibration microphone and adjust the equalizer with the speakers i already have.
although, the decibels are low enough that i struggle to hear.. which might actually be more problematic than calibrating the equalizer.

my situation is poor.. both financially and productivity based.
i've tortured myself enough.
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Old 14th February 2011, 05:40 PM   #18
niko084 is offline niko084  United States
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The worst position to be in...

I find it odd that the Precision Power amp allowed noise to bleed through, they are not what they once used to be but still are not known to be bad amps by all means.

Did you check your grounds and cables? Possibly test it outside of the cars environment?
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Old 20th February 2011, 11:06 AM   #19
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Quote:
Originally Posted by niko084 View Post
The worst position to be in...

I find it odd that the Precision Power amp allowed noise to bleed through, they are not what they once used to be but still are not known to be bad amps by all means.

Did you check your grounds and cables? Possibly test it outside of the cars environment?
the precision power amp was okay without the hifonics amp connected.
and that made me think the ground was okay.
i tried a few different places to ground the wire.
usually i ground to the trunk latch because i know there has to be a load of metal there, and i know that the bolt holding the latch touches a thick piece of metal.

if i could have changed anything, i would have purchased premium rca cables.
but i ran out of money and would have had to make an adjustment to buy simple cable ties.

sometime when i had the precision power amp, one of the channels quit working.
then later on down the road, one of my 6x9's either got some dust from the rear liner in the voice coil area.. or the voice coil started to short out.
either way, the installation was a living hell.
i hooked up some old school kicker r5 midranges.. but i had already ruined one of the voice coils when i had the speaker in the house.. that speaker finally died in the car.
i also blew a generic tweeter.
and when i brought the remaining (still functional) tweeter and midrange into the house, the tweeter decided that it didnt want to work anymore.
it was completely dead after sitting in the car without being used for 2-3 years.

- bought a bad amp
- one channel quit on a new amp
- totally blew out an old school kicker r5
- blew out a tweeter
- tweeter quit working once i brought it in the house
- broke an rca cord
- somehow damaged an infinity 6x9

had seven things go wrong before i could purchase a high output alternator.. kinetik powercell.. premium rca cords.. line driver.. equalizers.. front speakers.. and amp for front speakers.

perhaps not the worst that could go wrong.. but the list was kinda long considering i like to do it right the first time so that things dont break.

i mean.. i just installed a new oil seal behind the crankshaft pulley on my car.
the first one ripped and leaked oil.
had to do it all over again.
and then, less than 24 hours later, my headgasket popped its seal between cylinder and antifreeze 'runner' or 'port' (whatever you want to call it).

i had seen some mild white smoke in the past.. but i didnt know if it was going to rush into a major problem or if it was the cold.

i was upset that i purchased oil and antifreeze, and then it all drained out the next day.
now i will have to purchase more oil and antifreeze and remove the crankshaft pulley a third time.

probably the worst time it could happen too, because i am waiting for a letter in the mail about this agency getting me a job.
kinda hard to go to work without a car.
i mean, we have local buses.. but i dont know the schedule or the routes.
and we have a couple taxi services, but i cant depend on them to be on time.
besides, i cant fix the car if i am at work.

then i have my mother on her $5 cell phone calling me with like 15 people partying in the background.
she and i both know that her phone doesnt have a volume control and its hard to hear somebody talking.
and she calls me up and hangs up on me because she cant hear me.
then calls back and expects a conversation on the phone to be functional.
the second she said 'HUH?!'
i knew that once again i was a victim to her 'perogative' .. as ugly as it is.

i know that it would be real nice to get a new seal on my headgaskets.. because i have had a loss of power for years and i thought it was the software bugging.

i just did a compression test about a month ago and each cylinder averaged 150 psi
i dont know what the pressure is supposed to be new.. but the repair manual says a minimum of 100psi
which makes me think the engine has the potential to be of service for many miles to come.
i just dont have the $150 for gaskets, oil, and antifreeze.
and i just borrowed $160 that i havent had the money to pay back.

i cant see any way around the economy, as it is a money-hungry system with zero sympathy for those of us that dont have money and/or friends.

i feel like i am being used for the sewage i flush down the toilet and nothing more.
all the forums.. chatrooms.. and articles i have subjected myself to have done harm more than anything else.
being awake has lost its enjoyment and has become a burden.

not enough positive things to compensate for all of the negative things.
the economy is quick to shove itself in my face and tell me to buy something.
meanwhile, i have no peace of mind regardless of who or what i am interacting with.

how bout that for an electrical problem..!
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Old 20th February 2011, 11:31 AM   #20
AndrewT is offline AndrewT  Scotland
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Preventive maintenance.

Priorities.

These strike me as far more important than DIYaudio.
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