Cheap amp performance? What you think?

jol50

Member
2007-11-08 2:14 am
Has anyone here into audio actually run/tried one of these cheap amps? I had a pyramid way back in early 90s that worked ok actually, but no cheap amps since that I used in a car I drove except this current sort of cheap kicker. I have a couple I got blown now, ultra linear, pyramid, etc...going to put some parts in them new/used whatever (so I don't invest more than they are worth...that might be a challenge) and get them going...I will try them and see.

I'm just (seriously) curious. I have a few sets of good amps to try when I swap amps soon here like alpine/SS/etc...so I'm going to lay wires in the trunk so I can swap and figure hey why not compare some junk. I know they fall apart faster but how about sound? Will they be ok if they are huge amps so they stay away from clipping....or not? :smash: I will be using them full range off my crossover. I like quality sound a little loud sometimes and do not have DSP in this car.

If you have (or not) run any, what do you think will happen? :confused:
 
ive used bigger cheap amps to run fullrange and they work really well...the ones i use usually have 2 x tip35/36 per channel (4+4 total).

if the amp is strong enough, the speakers will distort before the amp.

only gripes are low slope crossovers and a bit less extension of detail.

where a good quality amp will carry more detaillllllllllllllllllllllllllllllllllll a cheaper amp will carry less detailllllllllllllll.

but youd never know the difference unless you A/B'ed the amps in comparison.
 

aznboi3644

Member
2007-12-15 3:00 am
I've used a Profile Baja HA1000

I put that thing through a beating...It put out some decent power...a lot better than other cheap brands.

I even had the amp wrapped in a fleece blanket wedged between the back of the box and the back of the rear bench seat. The blanket was to prevent vibration because I was lazy and didn't mount the amp.

I'm sure I was clipping the crap out of the amp. It got hot as hell but never even shut down or go into protection...just kept on pumping out power.
 

jol50

Member
2007-11-08 2:14 am
I may be able to put TIPs in this UL, it has 6+6 outputs...the factory transistors are too expensive. I saw where someone bought one new for ~80 on ebay lol. The other ones are only 2+2 except a 4 ch but have not looked at it closely yet. And I have an insignia that is 360rms bridged, even has a fan in it, plus a blitz that I think is around 75-100/ch x2. What a collection.:ashamed:

I need 400rms minimum for my 4 12s so will only run them on highs, unless the UL actually can do half of 900rms at 4ohms bridged. Even then I'd rather a class D for power reasons but I may test it just to further our quest for possibly useless knowledge .:scratch: :D
 
if you can find what the part numbers are for the trans...i can look them up in my master replacement guide if you cant find them online.

some of the KIA parts are hard to find crosses for....if it starts with something like 2skXXXX its probably a toshiba part.

heres one of the ghetto amps i used, but with 6+6 trans:
(i sold this actual amp to the ampguts contributor, it got hot as fark)

http://ampguts.realmofexcursion.com/U.S.Thunder_UST-4200/inside1.jpg


it was hooked up 2 ohms per channel (2 channel amp) four 6.5" components with tweets through the passive...it worked really good for mid/hi's...as long as you use a bigger amp than necessary, cheap amps work good for hipass duty.
 

jol50

Member
2007-11-08 2:14 am
ultra

http://www.digchip.com/datasheets/parts/datasheet/413/2SB817.php
2SB817 and 2SD1047 come up as sanyo, I think base resistor is 3.3ohm. PS is Fairchild 50N06, they are not so bad to get unless they are upgradable too, have not looked. Strange too is that on the board it lists B688A/D718A for outputs not what is in it. Don't think they have been replaced.

The insignia look a lot like the one you listed. This is the UL: http://www.savinglots.com/lotprod.asp?item=UL3200D It is longer/slimmer than photo looks.
 

jol50

Member
2007-11-08 2:14 am
Lol, I ripped into this insignia that was sitting here got two of them. One has blown channel ok, second tests ok/works but freaks out gets loud when bridged. I look and RCA has ground broken hmmm and why two channels difference like that? I pull board out and one rectifier stays on sink....turns out second rectifier and over half the fets have broken legs from assembly on that side, it also has PS for each channel. They are crooked and all clamps were factory glued. Common practice it seems but even a cheap amp can't work well if it is not put together all the way, it never worked right from day one.
 
I've been using an Audiovox 4 channel amp I bought back around 1994, and no problems with it so far. I chose it because it claimed to have protection circuitry, gave a plausible RMS watt rating, wasn't made in China, and Costco sold it.

I'd been slowly working on the Randall Vikan car amp from Audio Amateur, and got impatient to just have some tunes in my car since I was commuting 55km each way. Looking for protection circuitry was important since I'd tried the Vikan power supply with a simpler amp, and learned that the DC fault detection wasn't properly designed in Mr. Vikan's amp. (It was OK for positive DC faults, but marginal with negative going faults.)

Lately I've been wondering if the Vikan power supply wouldn't be OK to power a few LM3886 chip amps paralleled or bridged. I've got the parts to build at least 2 Vikan amps, and the power supplies are supposed to be good to 150 to 180 watts or so.

I wouldn't trust anything sold by Pyramid these days. I wish I'd kept a sample of the 18 gauge wire they claimed was 8 gauge in an amp wiring kit...
 

jol50

Member
2007-11-08 2:14 am
I have two pyramid, one is quite old and have to pull the boards to see anything in there but it has a lot of stuff in it. The other is newer and looks much like other budget amps. It only has 4 outputs so not sure what it will do but I had a kenwood that was 300rms bridged like that also that seemed to work well just got hot. Then again I don't know a whole lot about amp design...I go more by how many and what components are there. Actually at first glance the expensive amps appear to have more complex PS in them, often have inductors and things that cheap ones do not. I'm sure inputs are better also but harder for me to see easily. Back in the day cheap amps never had the power, I've tested some now like audiobahns that certainly have some power and sounded ok testing.

I'd love to build an amp had I the time, I'd like to semi copy a good old school one. One can make their own boards and use software to do it, would be a cool project. I'm almost surprised nobody makes a kit for that, like an old school 300w amp. Even a case and a board would do if costs could be contained.
 
jol50 said:

I'd love to build an amp had I the time, I'd like to semi copy a good old school one. One can make their own boards and use software to do it, would be a cool project. I'm almost surprised nobody makes a kit for that, like an old school 300w amp. Even a case and a board would do if costs could be contained.

im getting some 225 hcca boards made as a project, but i had to rearrange the traces for the caps that lay sideways, actually theres an option to use the original design or modern design caps, hopefully there shouldnt be any bad side effects.

hope theres no fire... :hot:

check it out, pretty cool huh? :D

[IMGDEAD]http://img206.imageshack.us/img206/7507/225hccaskewedtn5.jpg[/IMGDEAD]