Keyboard Shortcuts
ctrl + shift + ? :
Show all keyboard shortcuts
ctrl + g :
Navigate to a group
ctrl + shift + f :
Find
ctrl + / :
Quick actions
esc to dismiss
Likes
Search
2200 schematic found!
|
HEY! It's tax time, and I'm digging through stuff, and what do I find?
a 2200 Schematic sent to me about 3 years ago in the mail. One page is the Amplifier (one channel shown only), the next page is the LED Meters, and the 3rd page is the power supply config. WOW! Someone even marked it up with the replacement semiconductors. My question... Is the 2200 schematic similar to the 2201 Amp I own? What's the differences if any (besides cosmetics). -=Jeff Gross=- 450 W. Byberry Rd. #T22 Philadelphia, PA 19116 (215) 464-6077 [voice] (520) 752-4371 [E-fax] |
|
gurriesm
jgross@... wrote:
From: jgross@...I do not know myself. I know from what James said, that the circuits generally stayed the same. I do not have my SAE spec info with me, but I think the THD spec of the 2201 is like 0.03%. I do not think it is below 0.01%. If its 0.03%, it simply may be more of a biasing and feedback issue. I would know a little more by looking at the schematic and feedback design. The other clues can be found in a service manual which would talk about the proper biasing values which is also a clue. Would you be interested in selling me a copy of the schematic? James, how do you think SAE reduced THD in the later models. Best Regards, Mark Gurries ---------------------------------------------------------- Battery Charging and Power Systems Application Engineer Linear Technology,1630 McCarthy Blvd, Milpitas, CA, 95035 WRK(408) 954-8400 x3864 Email: gurriesm@... FAX(408) 428-9413 WebSite: ---------------------------------------------------------- Work & Hobby Related Website Info: Smart Battery Charging Systems: Model Railroad Club: ---------------------------------------------------------- |
|
Sell, Hell, I'll make a copy for you and turn it into a PDF file.
toggle quoted message
Show quoted text
I'll then e-mail it, or try to post it on the SAE talk file area. Also in PDF, I have the 180 / 1800 Para EQ manual.I was going to upload that, but it's like 200k in size, so I'll e-mail it to anyone who may need it. -=Jeff=- On Tue, 1 Feb 2000, gurriesm wrote:
From: gurriesm <gurriesm@...> |
|
sstinc:"First sstinc:Last"
Dear Mark,
toggle quoted message
Show quoted text
It's not so much as finding ways to reduce distortion but rather, examining history. Most designers "officially" rate the THD much higher than it actually is. This is done to cover the oddball unit that gets through production when maybe a tech stayed out the night before or had too much to drink, etc. Over time, the true history of the product performance shows that the spec can be lowered because when properly adjusted, all units will still fall below the new spec. Incidentally, the correct way to set the bias is by viewing the X-Y distortion residue output and NOT the quiescent bias current. There is always a wide variability in the characteristics of devices and so one bias level which is correct for one unit may indeed allow large nothches in another unit. As long as the thernal tracking is sufficient to cover all variations, there will be no problems. X-Y viewing is an east coast method created by the great Sid Smith at Marantz. It seems that the west coast boys (still) don't seem to understand the importance of viewing measurements this way where you can see not only the total distortion, but also, the phase of the lobes and the quadrants. I've given up trying to teach all of my acquaintences this technique because they just don't WANT to understand it. They continue to live happily in the stone age. If anyone wants to discuss this with me, I'll be happen to explain it. My number is 805 963 1122. My e-mail is jamesbongiorno@.... James Bongiorno gurriesm wrote: From: gurriesm <gurriesm@...> |
|
James is 100% correct. As a designer and builder of my own amplifiers in
the past, I found the bias measuremnts to be only a rough adjustment so as not to over-current the semiconductor devices initially. Typically on the initial powerup of the unit (one that has never been powered up before, ever), you set the bias current as low as possible. You then bring it up on the low side of the rating of the circuit, hook up your freq. generator and scope, then fine tune it from there. I usually run a dummy load using an actual speaker in a sealed box with lots of soundproofing in it. I run the initial test at 1000 hz, adjust crossover distortion as low as possible and monitor current as well. Do this initially at HALF the rated output, then try increasing. In proven designs, you might not need to be so very cautious. Then you want to try various frequencies, Very Low, very high, Do this at about 75% rated output. When you are happy, you can go back to the 1000hz, go to the rated output and do the fine adjustment. If it doesn't blow up...your design is successful. Be mindful that not many designs hold their stability all the way up to rated output. I then do a further burn-in by playing into a resistive dummy load, pulsating driving wide dynamic range music for a couple of hours, at near rated limits. I then monitor closely the heat dissapation and current. This final test has caught many amps that passed the frequency generators with flying colors. I haven't put the 2201 through this as it sounds great and I have a rule of not fixing what works. -=Jeff Gross=- |
to navigate to use esc to dismiss