I bought this Accurian Powerline home amplifier from Radio Shack today. You are supposed to use it to transmit and receieve audio through your powerline. They clearenced it from $150 to $20, so I couldn't pass up the offer to listen to it. Anyway, when I got home I opened it up and noticed it is a rebadged ST&T iMicro 84. I removed the powerline receiver, and took pictures of the amp section. The toroid is 28v-0-28v, 2A. Anyone care to comment on the quality of this amp design?
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Nice little amp, at 28V rails maybe 30w/channel with relays too but I don't think they are for speakers output. The TIP42Cs (power transistor) seem to be push to maximum mayde replacing with MJ15031 and it's complement will give better performance.
A BJT amp with 6800uF puffers and an 56V-CT mains trafo is able to produce 100W-RMS on 4ohm and 60W-RMS on 8ohm. But these output transistors wont survive a 4ohm speaker.
So that amp I think gives 60W on 8ohm, maybe 80W on 6ohm.
So that amp I think gives 60W on 8ohm, maybe 80W on 6ohm.
Nice images my friend.... pretty ones
Technical problems but good angle, good choice of angle to make the shot.
One more Artist in our communitty....good!
Having schematic or link to it, send informs please, to:
nanabrother@yahoo.com
regards,
Carlos
Technical problems but good angle, good choice of angle to make the shot.
One more Artist in our communitty....good!
Having schematic or link to it, send informs please, to:
nanabrother@yahoo.com
regards,
Carlos
Attachments
Nice internal layout
Internal layout is clean compared to other mass produced ones, even PCB looks decent and has torroid transformer too. I may get this one today. But it looks that this one is a good candidate for tweaking.
Internal layout is clean compared to other mass produced ones, even PCB looks decent and has torroid transformer too. I may get this one today. But it looks that this one is a good candidate for tweaking.
Sorry Carlos, I don't have a schematic, as this is a mass produced component. Maybe you could try e-mailing St&t (www.stt.com.tw), the maker of this amp. Some listening observations:
There is no center marking on the bass/treble knobs, and also no center detent on the pots. This makes it hard to tell if the bass and treble are flat. You can solve this by completely bypasing the front knobs and just using this as a straight amp.
There is a slight ground hum, and I'm trying to figure out why that is. For $20, this makes a perfect garage stereo/ outside amp. I agree, this amp could be easily modified to sound better.
There is no center marking on the bass/treble knobs, and also no center detent on the pots. This makes it hard to tell if the bass and treble are flat. You can solve this by completely bypasing the front knobs and just using this as a straight amp.
There is a slight ground hum, and I'm trying to figure out why that is. For $20, this makes a perfect garage stereo/ outside amp. I agree, this amp could be easily modified to sound better.
Accuriam Hotwire
Is there a way to convert this amp from receiving signals through the powercord to receiving signals through 'normal' inputs?
Is there a way to convert this amp from receiving signals through the powercord to receiving signals through 'normal' inputs?
Hi, all.
tschanrm, thanks for the tip. I just bought the last one for US$20 from the local RS store. It's either going to be connected to my computer or TV, I haven't decided yet. Here's a link to the ST&T spec sheet (.pdf file).
kec, thanks for the link to the mod. It's time to void the warranty. 😀
tschanrm, thanks for the tip. I just bought the last one for US$20 from the local RS store. It's either going to be connected to my computer or TV, I haven't decided yet. Here's a link to the ST&T spec sheet (.pdf file).
kec, thanks for the link to the mod. It's time to void the warranty. 😀
No problem. We don't need no stinkin' warranty!
You can still get these from RS online. I just got 2 shipped from Texas and shipping was only $8 for both units, not a bad deal at all.
My next step will be to bypass/remove the bass treble tone controls. Upgrade the volume pot to a better one. And maybe upgrade some of the critical parts with better ones.
-Ken
I picked up one today. With the modification complete, the amp is running. I must say the power supply parts are worth the $20 I spent. If worst comes to worst, I have a complete power supply for my next gainclone. I think I will bypass the preamp section entirely. The easiest way to do that is to splice the rca jack wire with the L center R on the amp board? Hopefully this is a 50 Hz high pass filter on the preamp board, just thinking.
I think I will get two more amps today.
I love the idea of a complete power supply for $20.
I think I will get two more amps today.
I love the idea of a complete power supply for $20.
I'm on the Accurian bus as well. My intention is to use it as BillH has with his PC. I have not built the speakers yet, but I am thinking of a set of Aurasound NS3-193-8A's.
thanks
aia
Being a Newbie, could you please keep me (us) posted on what (and why) those mods will be? This is my first foray into the innards of such a device and Id' love to learn the art of tinkering.
thanks
aia
This weekend I completely removed the control board (volume, tone controls). I replaced the volume pot with a Radio Shack (271-1732) 100K Alps pot that I had laying around (the stock pots are 100K).
It appears there are 4.7uF input caps (electrolytic) on the control board, so I added 2 Solen 4.3uF poly caps to the input of the Alps pot.
Usually, the idea is to remove any components in the signal path that would degrade the audio signal. Since this amp has tone controls in the path, this IMO degrades the signal - so out it goes.
Although the RS Alps pot isn't considered a "good" pot, it's certainly better that the stock one. At one time Professor Leach thought the RS Alps was a decent pot - at least for his amp that is.
So, how does it sound? Very good IMO. Definately better than the stock arrangment. My source is an unmodified PS1 with output from the A/V connector - haven't done any mods yet.
One other mod will be the speaker connections. I'll try to find some better binding posts that will fit the chassis.
I'll post some pics when I get done.
-Ken
It appears there are 4.7uF input caps (electrolytic) on the control board, so I added 2 Solen 4.3uF poly caps to the input of the Alps pot.
Usually, the idea is to remove any components in the signal path that would degrade the audio signal. Since this amp has tone controls in the path, this IMO degrades the signal - so out it goes.
Although the RS Alps pot isn't considered a "good" pot, it's certainly better that the stock one. At one time Professor Leach thought the RS Alps was a decent pot - at least for his amp that is.
So, how does it sound? Very good IMO. Definately better than the stock arrangment. My source is an unmodified PS1 with output from the A/V connector - haven't done any mods yet.
One other mod will be the speaker connections. I'll try to find some better binding posts that will fit the chassis.
I'll post some pics when I get done.
-Ken
kec,
thanks for the mod update. The concept of keeping the signal path uncluttered seems logical.
I presume that you can use the 4.3uF caps in place of the 4.7uF caps because the value difference is under 10% and that the poly caps are more desirable than electrolytic caps?
aia
thanks for the mod update. The concept of keeping the signal path uncluttered seems logical.
I presume that you can use the 4.3uF caps in place of the 4.7uF caps because the value difference is under 10% and that the poly caps are more desirable than electrolytic caps?
aia
Today, I bypass the preamp section. I hooked the amp to an AD815 preamp. I agree with kec, the more junk you take out of signal path, the better the sound (all those 4.7 elec and IC in path). It is a big improvement (smoother). I think a simple Jfet buffer and preamp would do right by this amp. BTW there is an 18k resistor in parallel with the 100k pot. The dc offset at output changed a little,one channel went from 0 to .3mv the other went from 4.8mv to .3mv. With upgrades,I think this amp would make a good gift. I got two more today, looking to get more over the weekend.
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