Home » Sponsored » Pi Speakers » cheap skate amp award?
cheap skate amp award? [message #35623] Thu, 21 March 2002 11:21 Go to next message
Sam P. is currently offline  Sam P.
Messages: 307
Registered: May 2009
Grand Master
Wayne,
I just discovered that my entire HT system is powered by LM1875's at 20-25 watts per channel. So I will be driving the JBL4648a-8/511 horn systems, as well as the 4 Pi Pro's...with $2.34 worth of amplifier per channel. I hope someone else will claim this award...even if I have to bribe myself with a new ht receiver! Sam
Re: cheap skate amp award? [message #35625 is a reply to message #35623] Thu, 21 March 2002 13:17 Go to previous messageGo to next message
Chris R. is currently offline  Chris R.
Messages: 82
Registered: May 2009
Viscount
I'm supposed to take delivery from UPS today of a Klipsch V.2-400
computer speaker amp. Its 4x60W + 160W subwoofer (80Hz). I plan
on making an active crossover and use it to bi-amp the JBL 3677's.
It was $100. Crossover will cost me maybe $20 to make. I think
I have an LM 1875 in my little Marshall practice amp. They claim
its 15W into 8 ohms.
Re: cheap skate amp award? [message #35645 is a reply to message #35623] Fri, 22 March 2002 10:43 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18791
Registered: January 2001
Illuminati (33rd Degree)
Do you have a spec sheet handy for that device? What's the distortion spec on that chip? I've seen some cheapo car stereo IC's that actually performed pretty well, if they have a rock-solid Vcc line. Then again, I've seen some real junk too. Remember the old Pioneer Supertuners? Bulletproof, but 10% distortion.

Just for nostalgia, I put one in the Olds. Never had one back when they were "cool" - I ran Concorde stereos and JBL Pro (2105, 2115, 2405) drivers exclusively. Some might have considered that "snobbish," but it was the only car stereo I knew of in the late seventies that was any good. Really good - cassette out to 22kHz!

actually on paper they look great [message #35648 is a reply to message #35645] Fri, 22 March 2002 11:53 Go to previous messageGo to next message
Sam P. is currently offline  Sam P.
Messages: 307
Registered: May 2009
Grand Master
with 20 watts output into 8 or 4 ohms, at 0.015 % distortion. The National Semiconductor specs sheet says they can do 25 watts/1% distortion run at +/- 30 volts. Admittedly my HT thingy has a crap p/s, but it could be upgraded easy...but I hate to mess with something that has OVER 60,000 hours running hot, and still works. I did not even bother to verify the supply rails voltages while I was in there blowing away 7 years of dust bunnies. Once motivated, an hour with the desolder/soldering tools and all the electrolytics would be upgraded and bypassed. Then it would spectacularly decide to let all the smoke out the next day... :(
As an aside, the $800-1000 denon HT dvd player/receiver I recently considered FREAKED ME OUT when the THD spec was 10%...wattage and amp types unknown...still liked it though...but 10% THD???
The national semiconductor LM1875's cost $2.34 each from ratshack.com, my HT uses $14 worth of power amps at present. I'm now considering finding a decent, more state of the art "stand alone" surround decoder, and building a higher wattage DIY version of the 3M unit for amplification chores.
Pioneer makes a super tuner radio for late model GM trucks too. We almost put one in the 96 Sonoma (ZQ8 "SS" running gear), then her radio started working again. Intermittent demons would change the modes/volume at will. and then the volume would get loud on it's own, and not decrease when the control was turned down. At least the off always worked! Then it works fine for the last year. Sam
Re: actually on paper they look great [message #35655 is a reply to message #35648] Fri, 22 March 2002 17:36 Go to previous messageGo to next message
bmar is currently offline  bmar
Messages: 346
Registered: May 2009
Grand Master
Hi Sam,

I was thinking about building a Tripath. wondering if you have any input about those.

which Denon did you look at with that ugly spec? I cant find any THD specs like that.

Bill

check out the denon DHT-700DV [message #35663 is a reply to message #35655] Sat, 23 March 2002 07:29 Go to previous messageGo to next message
Sam P. is currently offline  Sam P.
Messages: 307
Registered: May 2009
Grand Master
at the crutchfield site. The amps are 35 watts/5 channels @ 10%THD into 6 ohms. Sub is self powered at 50 watts, again 10%THD. But when you read the detailed specs, it does lots of neat stuff...front speakers "size" can be specified, varied "soundfields", aspect ratios, etc. All I want to do is watch movies once in a while. I'll bet the amps are pretty "clean" at lower wattages anyway. BUT 10% THD. For $1K? But that does includes the DVD player builtin, with MP3 capabilities too. It was "neat", but not enough power above where I am now to make much difference(and who needs another set of 5 inch high "monitors"). But as a "turn key" HT solution, pretty attractive. Sam
Re: check out the denon DHT-700DV [message #35665 is a reply to message #35663] Sat, 23 March 2002 09:53 Go to previous messageGo to next message
bmar is currently offline  bmar
Messages: 346
Registered: May 2009
Grand Master
Hi Sam,

your right, thats a hideous spec! i thought it was a typo and checked out Denon too. same thing, 10%.
if your inclined to spend that much, you could check out other Denon or Onkyo HT receivers, and a DVD player that would run MP3 files.
heck you could probubly get into those two units for 500 if you just want to use it for HT.
I scatter the misc, "5"monitors" around the house as coasters and foot rest!

Bill

separates are probably the way to go [message #35666 is a reply to message #35665] Sat, 23 March 2002 11:27 Go to previous message
Sam P. is currently offline  Sam P.
Messages: 307
Registered: May 2009
Grand Master
I was just attracted to the "one box" convienience, as well as the similarity to the amp system I use now. I need a second audio rack for HT now! I'll check the Onkyo line out too. Wife just wants to play a DVD now and then when friends at work offer to loan them, I'd rather spin vinyl or cd's...Sam
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