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Old 11th June 2010, 12:06 PM   #11
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Reminds me of the management physics class were they use gravity as 10 m/s ^2.

So the min rule of thumb is take your lowest note, go down 1.41 octaves, and thats the freq you should shoot for to avoid phase problems?

Phase Response in Active Filters: Analog Dialogue: Analog Devices
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Old 11th June 2010, 04:56 PM   #12
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Quote:
Originally Posted by nightanole View Post
Reminds me of the management physics class were they use gravity as 10 m/s ^2.

So the min rule of thumb is take your lowest note, go down 1.41 octaves, and thats the freq you should shoot for to avoid phase problems?
That is my rule of thumb, yes.
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Old 15th June 2010, 02:31 AM   #13
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so for my purposes then, there really isn't anything non-technical i can do to get more output from the amp except unplugging the ports on my mission bookshelfs i'm taking it. i wish i could bridge my two units to double power but know that can't be done.

thanks for your help everyone. i'll leave the advanced tweaking to the rest of you as most of this thread's replies went over my non-circuit building head.

Quote:
Its also the reason why you cant hook them up to headphones, a filter for a 4-16 ohm load is not going to work on a 64ohm pair of cans
taking a headphone level input & then amplifying it is a bit of overkill and only adds and extra layer of distortion to the circuit path. i guess maybe you're talking about using it with line in. i'll be using my amp with an excellent sounding cowon media player that's biggest fault is having slightly less treble air than a sony DVD player with uncompressed WAVs.
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Old 25th June 2010, 12:20 AM   #14
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what about putting a heatsink on the chip or on the big "solder field" (i don't know the technical term) on the back of the amp for improving reliability? i plan on driving the amp just up to the level where i can hear distortion for continuous use about 4 hours at a time. my previous sonic impact amp eventually blew up. it would play fine for about 2 minutes then distort & fade.
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Old 25th June 2010, 02:18 AM   #15
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Solder field is called a thermal pad. You can put a heatsink on the thing. I was suprised how much cooler mine ran just laying it on a piece of thermal rubber and an alum plate, at an angle even.

The only other way i can think of to get more power out of it is to figure the max voltage limit of the chip and tweak the power supply. It would have to be regulated.
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Old 25th June 2010, 08:49 PM   #16
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i'm going to be using my amp with 8 X AA (2500mH energizers) as i did when my sonic impact was still working. what i REALLY wanted was a higher power sure or connexelectronics unit but both vendors are paypal only and i have a "fool me twice" grudge against paypal/ebay (same company). i particularly like the both the symmetry and the black on black look of the sureelectronics' TK2050 "100w" over the fugly yellow of the connexelectronics' 70w amp. i would have liked to put a TK2050 under a plexi window with deep cobalt blue (UV simulated) LED lighting.

never heard of "thermal rubber". my understanding is that anything between the surface & one is cooling other than the heat sink (or pipe) including thermal paste lowers efficiency & that a properly lapped direct connection is best. i also considered elevating the amp & putting a tiny fan on it.

i'm taking it then, that a heatsink would work better on the back of the amp on the thermal pad then. it makes sense as metal conducts heat better than the plastic on the chip. i'm sure the amp would be happier with some extra cooling doing long stretches at full power.

thanks for the help there. now to find a small enough heatsink, preferably copper.
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Old 27th June 2010, 02:32 AM   #17
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it wasn't easy finding smaller heatsinks at all. early on, i found these EXCELLENT ones for the job, coolinnovations 4-070508P splayed copper heatsink
17.27mm L 13.72mm W 20.32mm H, but they appear to be one of those big companies that can't be bothered to deal with small orders.

i found a bunch of small copper ramsinks that would work, but they're a bit overpriced at $20 a kit. the heatsink would cost as much as the amp itself there.

the best ones i could find for sale individually were these black annodized aluminum finned 20mm X 14mm X 7mm units
http://www.electronicplus.com/images...ts/EC-HS-E.jpg

there's space on the back of my amp for up to an 17mm W X whatever L heatsink except one of the corners of the thermal pad is cut at a 45 degree angle with another line of solder that would short out if i went that wide. do thermal pastes & tapes insulate against electricity, or would they cause shorts?

Last edited by budget minded; 27th June 2010 at 02:34 AM.
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Old 27th June 2010, 12:32 PM   #18
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Thermal paste and tape do squat for insulation. Thats why they have mica insulators for the lm317 regulators and stuff. Most heatsink paste isnt conductive, but as soon as the heatsink pushes into a lead...

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you dont need anything huge, A ramsink would do it.


230485038987

ATI X1650 2600 650 3850 HD BGA Heatsink Ramsink Cooler - eBay (item 230485038987 end time Jul-07-10 15:55:57 PDT)
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Old 28th June 2010, 12:13 AM   #19
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i'm 100% sure a ramsink is better than nothing (but not worth $20 in this lifetime) as the amp module will work for at least a couple weeks worth of full volume without one, but i was looking for an overkill solution.

if bridging circuits is a bad idea, then i just won't do it and will work within the confines of the thermal pad then. thank you for clearing that up. i figured it was probably a bad idea but was hoping i could put a big porcupine heatsink in there.

before i buy one online, i'll see if i can find an old CPU unit i can cut down with a hacksaw at the local recycle store. i'd still like to get as big a contact patch as possible. if i can't find anything suitable, i'll just get a couple of those 14mm X 22mm finned aluminum deals. they're about the perfect size and only a couple bucks each.

i think before long, i'll just clench my teeth tightly and deal with scampal to get a 70wpc connexelectronic amp. 15wpc disappears the second you ride within 50 feet of a nightclub. if they weren't $100, i'd get a 50wpc Dayton DTA-100, but i can DIY a more powerful & possibly better sounding unit with the connex units.

thanks again
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Old 28th June 2010, 01:37 AM   #20
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Honestly the last time i used a aluminum screw for my headphone opamp heasink. Jb weld is not conductive and you could go nuts with it...
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