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Class D Switching Power Amplifiers and Power D/A conversion

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Old 22nd December 2011, 11:48 PM   #1
diyAudio Member
 
Join Date: Dec 2011
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Default Very new here and very excited.

Hello DIY forum.

I am happy I found my way here.

I am looking to get into separates in my home theater setup.

I have been looking around for amps and was going to settle for a emotiva.

but then i found the velleman kits and some gainclone amps. I have decided i would like to build my own amp, as I love the little vellemen kits you solder together.
plus i think it will be very rewarding and it is a process i can do one at a time.

Here is some stuff about me.
I studied cinematography. I work in the entertainment industry as a electrician. my use and knowledge of electric is different compared to what is needed here.

I learned how to solder in my high school years while working at a auto garage. I have loved it ever since.

I love knives, more importantly sharpening them, i have a set of synthetic Jap stones from 250 grit to 12k grit and then i have different leather strops and compounds. I recently got a 1x42 kalamazoo belt sander for speed sharpening, i love that too. Been sharpening for 12 years now since i took my first job in a sushi restaurant. If you guys need an edge on your blades let me know.

I love audio, going from my boom boom days in college, yes i had cerwin vegas, to a more refined and detail oriented sound i have recently finished my 7.1 theater game system of the polk audio monitor 70II cs2II and 4x monitor 40IIs. I completly rebuilt the XOs on each speaker with decent budget components, clarity cap PX, mundorf MOX resistors, and solen perfect lay air coils.
I know the monitor line is not considered high profile, but I have to build things as my money allows me. I felt they were a great launching platform into more detailed audio.

Other things you all should know, I can use a DMM, i can read a very basic schematic, however diodes and their position always throw me off. I have a very basic idea of circitry, i know some parts and what they do, caps, coils, resistors, transistors ect, again very basic.

things I can not do:
i dont have many of the scopes and very detailed testing equipment some of you have.
i can not design a circuit.
i do not possess electrical engineer knowledge or the math needed. so i can not make a judgement to adjust, a resistor, or capacitance ect.
i have not yet done SMD soldering.
i do not know how to calculate a power supply.
i am generally nervous as i am new to this.

but hey i can solder thru the hole and not destroy the pads.

here is what i want.
I would like to build mono blocks. Because of money reasons, i can build one amp at a time.

The system now and in the future will be 98% video games and movies. 2% music, not as a listening session, but just there as i cook dinner, clean ect.

the system does not need volume pots in the amp, i have a head unit with pre outs that can control them. Sony 5600es. do i need any special input board for unbalanced rca inputs?

I want, 300watts into 8ohm. i have 8 ohm speakers now.

i want the amp 4ohm stable as well, what ever wattage is fine, i know it will be more than 300.
I have plans for upgrading my speakers to polks flagship line of LSI and those are 4ohm, i would like to build a amp i can have for many years and not have to change as my impedance changes.

i want, great sound. here is were i must admit defeat, i think a rectifier switches ac to dc, is that correct? I dont know what a snubber is. I understand soft start but how to do it i do not. Does every amp need a voltage regulator? what is a rectifier?

all of those parts i found on 41hz website, while looking at amps and power supplies they would suggest x item, which regulates voltage, or this one is a bridge. I dont know what each component does and dont know if i need it.

Lastly, since i cant measure sine waves or can not calculate component values. I would like use a kit as my first build. Similar to the velleman style, with a PCB and it says R1, C1, T1 ect, then there is a paper that says R1=100kOhms blue body, stripes: orange, green, black, gold. hook this board to that board, i think you guys get the idea. If the PCB doesn't have the parts placement a print out of the PCB showing where components are located would work too.
Just like a model plane, follow the instructions and all will be ok.

I have been looking at the 41HZ website it seems some of their kits would work.

I am willing to learn circuity but for my first build i would like to follow a secure design, just solder away.

I can build my own enclosures, so do not fret about that.

Sooo, long post short, please can you advise any kits to meet my demands? From where?
what extra parts does one need? Bridge, soft start, voltage regulator, rectifiers?
what does each one add to the amp? you can be general, no need for a PHD electrical engineer course.

Thank you so much for reading this far and your thoughts!
I am looking forward to having many discussions about electronics with you all. Also posting photos as I work on each amp.

ESR
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Old 23rd December 2011, 10:14 PM   #2
diyAudio Member
 
Join Date: Dec 2003
Location: Munich
Hi ESR !
Welcome to the forum.
I also think that a proven KIT is the best starting point.
I have to admit, I am not the right one to propose a particular KIT. Never digged into this market place.
But I think, you will find multiple threads about different KITs and/or modules.

Enjoy!
Markus

P.S.
Don't be nervous.
...but patient...
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Old 24th December 2011, 01:23 AM   #3
savu is offline savu  Romania
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Hello ESR.

Are you interested in Class D amp kit or Class AB kit?
The idea is that Class D kits are hard to find because of the switching topology being not so build friendly. In other words is more simple to start to use a Class AB audio amp kit because of the simplicity of building and testing.

My taught is to start with a Class AB kit and after you make it work, do all the measurements and tweaking in order to understand how to properly use a DMM, how to chose a power supply and so on.

And to get you slightly motivated ... watch this guys video blog: EEVblog's Channel - YouTube

Feel free to mail me anytime: "savu_silviu@hotmail.com"

Regards,
Savu
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Old 24th December 2011, 01:26 AM   #4
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Thanks for your reply Choco.

I have determined this, for my first build since there are many factors i want to take my time with in learning the amp building process, I have decided on a module that has been assembled for me. As i was reading on the 41hz website and forum there is a lot of tiny detailed space measurements to watch on your components or you'll short them or other disastrous results.
so my brain says, even though i can solder thru hole, should i do this at a first go?
i think i should tame myself a little bit. with a module i can get a power supply a transformer and all the other small parts and put it together see the process, then later dive a step deeper into the process.

Having said about modules, can you guys offer any companies that i havent found?
i have visited:
chipamp, 41hz, class d audio, i read the thread on them too, i am impressed.
I visited krell but those seem to be fully assembled amps.

then my second thought, hashing out a transfomer.
i am interested in a class d board.
the TI600 seems to fit my needs.
it is speced to use a single 50v transformer at 400va or you can order a 1000va.
i have noticed the an-tek torriods have 2 secondaries.
like the 2x50v/1000va.
i have also learned that the va is the total load you can put on the transformer.
my question is this,
if you have, say, the 2x50v/1000va transformer
and then you run 2 of the TI600 boards each with thier own PS board connected to its own secondary from the transformer, do you then have 1x50v/500va per secondary? or does each amp board draw what it needs out of the 1000va?
secondly is that transformer ample to run 2 amp boards like that or will there be heat and low voltage issues resulting in failures in the boards? output wattage is 2x300 per board.

i hope i am clear in my questions. if not just ask!

thank you for your time.
esr
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Old 24th December 2011, 01:46 AM   #5
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Thanks savu,

I am looking at class d/t boards.

as you can now see i have decided to really tame myself and for a very first out of the bag go, use a module.

take my time to hook it up and then, after some time perform some light mods, increasing the cap values on the PS, perhaps change out the output caps to nicer ones like clarity caps or others and perhaps the output resistors to some mills or something. again thats after the fact it is built and working.

first i am looking forward to many conversations with you all about electricity like my power supply question above.

thank you for your time
esr
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Old 25th December 2011, 03:20 PM   #6
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Quote:
Originally Posted by esreuter View Post
..if you have, say, the 2x50v/1000va transformer
and then you run 2 of the TI600 boards each with thier own PS board connected to its own secondary from the transformer, do you then have 1x50v/500va per secondary? or does each amp board draw what it needs out of the 1000va?


esr
Basically it should be possible to use a 1kVA transformer and use one secondary for each amp. The transformer then can handle 500VA on each secondary at the same time.
If you load just one secondary - you can draw slightly more than 1x500VA (but not much more).
Basically if the amp draws more, the transformer will deliver more but generate excessive heat. That is sounding more critical than it is. In fact a 2x600W class D amp can be easily supplied by a 1kVA transformer, because music program does not draw high continuous power.

BUT TAKE CARE:
The TI600 needs 50V DC. Means you should use a transformer with max. 32V secondaries.
Why? 32V at the transformer means 32V AC. Means 32Vrms with a peak of 45V. The caps behind the rectifier will be charged to this peak value minus 2x0.7V (2x0.7V = 2x forward voltage of a diode) and store it.
Why would I use a transformer that ends up in 43V-44V DC if 50V are allowed?
1. If the AC mains input voltage goes up, then the DC output will also go up.
2. At low load or no load - transformers show slightly higher voltages than the specified output voltage (depending on type 3-15%).

Last but not least, if you chose one transformer with two secondaries, make sure that it really has two separate secondaries. Sometimes people also say '2x30V' for a center tapped 60V winding - likely this would not work for two TI600 boards.
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Old 25th December 2011, 03:36 PM   #7
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Note:
ClassD also offers the TI-600 KIT, which encloses the transformer and rectifier and caps.
P.S.
You mentioned about budget. The TI-600 is not what I would call a low budget approach. Cannot tell anything about sound and quality, so I cannot tell you if it is worth the money - for this info better search the forum and check for opinions of the DIYers who use this amp.
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