"The Wire AMP" Class A/AB Power Amplifier based on the LME49830 with Lateral Mosfets - Page 203 - diyAudio
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Old 5th January 2013, 07:51 PM   #2021
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Time / cost / complexity ... The Wire amps themselves are great little units, it just the implementation. I had a few problems with the dps-600's (I broke them) and my inexperiance started to show... As time moves on, motivation moves from one project to another and with it goes the money. I would like to complete this at some point this year, but it wont be in the next 3 or 4 months.

Paul
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Last edited by BuildMeSomething; 5th January 2013 at 07:55 PM.
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Old 8th January 2013, 05:06 PM   #2022
Zebb is offline Zebb  United Kingdom
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Owen,

Could I ask you if you think that Semlad's 8A 160v Alfet Mosfets, ALF08N16V/ALF08P16V, would be appropriate for a "less demanding" version of this amp, and if that would need any major design changes?
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Old 8th January 2013, 08:45 PM   #2023
Zebb is offline Zebb  United Kingdom
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Ooops... "Semelab"... not Semlad
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Old 14th January 2013, 07:57 PM   #2024
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here are some pics. This is a 2 channel version, single ended input, one pair of output fets per channel. When I first saw the bare amp boards I thought it would be a piece of cake to put them into an old kenwood chasis. Boy was I wrong. I kept adding stuff and I had less and less room. To change a part on the amp boards now takes 1-2 hours of dissassembly and then reassembly. I was going to use one power supply for the front end and the outputs with 6 x 10,000uf caps. I was looking around ebay one day and came across some epoxy cast transformers 0-15, 0-15, 200ma output. I thought the transformer would fit perfect. It did. I had a bit of trouble adding another bridge rectifier and 2 more caps. There was a bit of space on the powersupply board to add a +24v supply for the front panel VU led display. It didn't take too much effort to add a couple more +/- 75v regulators for the LME front end. I moved the DC protect/speaker relay board to the rear heatsink bracket. I found a couple of socket fuse holders that had room inside for 10ohm resistors so I could check the bias whenever I needed to. I tried to keep the leads as short as possible, but I had to make some of them a bit longer to make service easier. I had too much trouble to twist the 14 guage power wires so I left them straight. Why did I use 14guage, because I had some. I added some output zobels and a coil near the speaker binding posts. You can see the epoxy transformer just below the transformer in the first photo and the socket fuse holders with the resistors just above the filter caps.

The build was not without grief, what looked like 120khz osscilation was an old CFL lamp on the work bench. Little 68khz pulses was the battery charger for my hand drill. A 10.6 mhz osscilation was the heatsinks not grounded. A 1.25 mhz oscilation was the output caps I forgot to put on the lm3xx regulators. I put 10uf close to the regulators and oscilation gone. I had a ground loop buzz when hooking up a cd player to play some music. I removed the 0 ohm jumpers on the boards to solve that one. I don't know what it sounds like as it is playing through some junk speakers.

With +/- 65 volts on the fets and +/-75 volts on the front end, power is a hair over 150 watts @7.5 ohms per channel just before clipping. My load resistors are 2.5 ohms. If you remember a few posts back I changed the feedback and input resistors to 30k ohm. I kept the original caps 330uf and the bandwidth at 10 watts is flat from 1hz to forever. I say forever as my generator only goes to 110khz. Before I put on the output coils and zobel, full power bandwidth was past 60khz with some obvious slewing above 100khz

The powersupply board is a single sided circuit board that I removed copper with a dremmel tool as needed. You can see where the dremmel tool slipped on the rear of the amplifier as I was trying to enlarge a hole for the fuse holder.

The amplifier has been playing on the workbench for a couple of days now and I will hook it up to the livingroom speakes when the wife is not home. She retired over the holidays and for some reason I don't have much free time lately.
Attached Images
File Type: jpg amp1.jpg (309.8 KB, 651 views)
File Type: jpg amp2.jpg (238.0 KB, 538 views)
File Type: jpg amp3.jpg (402.1 KB, 523 views)
File Type: jpg amp4.jpg (311.6 KB, 500 views)
File Type: jpg amp5.jpg (315.6 KB, 471 views)
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Old 14th January 2013, 08:37 PM   #2025
rsavas is offline rsavas  Canada
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Good job!! thanks for the update.
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Old 16th January 2013, 10:07 AM   #2026
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Quote:
Originally Posted by IanAS View Post
..
Would that 0.22 or 0.33 not be swamped by the 6Ω(?) resistance of each mosfet? I looked at the data sheet but there's nothing there about resistance.
The use of sorce resistors has nothing to do with the Drain-Source resistance of the used transistors. Source or Emitter resistors are used for thermal stability. You can read all about design considerations in this article:
http://products.semelab-tt.com/pdf/A...nNoteAlfet.pdf
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Old 16th January 2013, 10:41 AM   #2027
miklos is offline miklos  Canada
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Quote:
Originally Posted by Zebb View Post
Owen,

Could I ask you if you think that Semlad's 8A 160v Alfet Mosfets, ALF08N16V/ALF08P16V, would be appropriate for a "less demanding" version of this amp, and if that would need any major design changes?
Amazig, they can make a pdf file with no info on the pinout. Is that follow the Hitachi schema, or is the drain pin#2 ?
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Old 16th January 2013, 12:25 PM   #2028
AndrewT is online now AndrewT  Scotland
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The Pin Out is specified.
You just need to read the pdf Datasheet more fully.
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Old 17th January 2013, 03:56 PM   #2029
miklos is offline miklos  Canada
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Quote:
Originally Posted by AndrewT View Post
The Pin Out is specified.
You just need to read the pdf Datasheet more fully.
Thanks, last line.
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Old 18th January 2013, 05:43 PM   #2030
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The wife went out shopping today so I was able to hook up the amp to the living room speakers and do some listening.

PFG is my immediate inpression.

Thanks Owen
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