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Chip Amps Amplifiers based on integrated circuits

audiosource amp100 (tda7294) mods
audiosource amp100 (tda7294) mods
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Old 27th August 2011, 08:15 AM   #11
ashok is offline ashok
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audiosource amp100 (tda7294) mods
post #2 sounds good. Reducing the supply voltage might only insure that the chip doesn't go into protection mode with 4 ohms which possibly sounds raspy(?). However it will of course still clip if over driven.

Might be better to stay with the higher voltage and not turn up the volume till clipping or get into over current mode.
Wonder if the protection circuitry will let 'some' clipped signals through for a few miliseconds before it kicks in. The dc blocking cap at the input can be quite critical !

About supply caps. For any significant change maybe you will need to double it's value but that also depends on the capability of the supply transformer. With small transformers increasing the supply caps might not help at all. There is always an optimum value that you might need to test and find out for your particular amp.
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Old 12th November 2011, 08:42 PM   #12
David Eltzroth is offline David Eltzroth  United States
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I brought an AudioSource Amp100 for use with a pair of ROX Studio 9 monitor speakers and a Flat Panel TV. Out of the box I was not real impressed. I decided to modify the unit to my liking. The mod was fairly easy and rendered worthwhile results. I am going to list the changes that I made to my unit for anyone who wants to paint by the numbers and upgrade their unit. I am assuming that you are experienced with equipment repair, good soldering practices and you have the right set of tools. If you are a novice donít even try this mod you will end up with an expensive non working amplifier. Remover the Input PC board from the back of the metal case. Remove the Main PC Board from the bottom of the case, pay attention to where the screws and other parts came from. On the Main PC board Change C104 and C207 to 10uf at 16volts non-polar. Remove IC#1 (5532) and install an 8 pin dip socket (donít be cheep here) Replace IC#1 with a Burr Brown OPA 2134. Replace C101 and C201 with 4.7uf 16 volts non-polar cap.
On the Input board Change C411, C414, C413 and C412 to a 100uf 16volt non-polar cap. Remove IC #4 and #5 (5523) and install an 8 pin dip socket Replace IC#4 and #5 with a Burr Brown OPA 2134. Change R426, R428, R429 and R427 to a 10K 1% resister. I think if you want to further improve the amp after you have made modifacations that are outlined here, A complete new PC board would be nessisary. It may be worth doing because you can't buy a case, power transformer and all of the pysical stuff (conectors and so) on for the 100 or so dollars that the amp 100 cost. Remember, this is what I did to my unit and your outcome may be different so I can not take any responcibilitys for your results.
You can get all these parts at DigiKey or Mouser. I hope this helps.
David Eltzroth
Rox Electronics, Inc.
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Old 24th February 2012, 01:28 AM   #13
dekes1 is offline dekes1  United States
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Default Repairing blown Amp100

David (or anyone else with this amp), can you tell me what the original values of C401 and C402 (on the amp board) are? I have one of these amps that's had a meltdown and I'm trying to piece it back together.

On a related note, does anyone have a schematic for this amp or know where I can get one? If I can't get the amp working, I'd love to use the input board for another project since it has the built in bridging capability.
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Old 3rd January 2016, 12:56 AM   #14
jeflawlor is offline jeflawlor  United States
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I have a audiosource amp100 with the left channel not working. I am using it to run my electronic drum kit (mono). I wouldn't mind selling it if anyone is interested.
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Old 3rd January 2016, 02:57 AM   #15
Ron E is offline Ron E  United States
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Yet another zombie thread, this one was replied to with a 'for sale' advertisement Good luck getting much for a half-functioning cast-off.

For anyone who is interested in buying or modding the Amp100, fully working examples can be had for <$40 secondhand. There is a guy on the Parts Express tech talk who has modified this amp, and come up with a how-to-improve list...
How to turn your AudioSource AMP 100 into a real amp. (Paying it forward))
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Last edited by Ron E; 3rd January 2016 at 03:24 AM.
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