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How to turn your AudioSource AMP 100 into a real amp. (Paying it forward)

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  • Psycoacoustics
    replied
    Re: How to turn your AudioSource AMP 100 into a real amp. (Paying it forward)

    Ok Buddy here ya go. I'll also e-mail them to you in case that will work better.

    I left it apart on the bench so if there is anything else you need, just ask. Later, Mark
    Attached Files

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  • Psycoacoustics
    replied
    Re: How to turn your AudioSource AMP 100 into a real amp. (Paying it forward)

    Originally posted by tyger23 View Post
    Well, when life hands you lemons....

    I tweaked my back yesterday and that meant I wasn't outside doing oodles of yardwork today. It's hard to complain when you get out of yardwork, but it stinks being immobile. So, I spent the day tracing the PAMP1000 circuit and drawing up schematics for it. I found out a few things - Pyle copied the AMP-100 schematics almost exactly. The reference designators and some of the layout change, but they're pretty much the same.

    That also brought me to a separate conclusion - one that's important for anyone who's bridging these things with my mods (like Psychoacoustics). There's another resistor that needs to change for the bridging scenario. In the bridged mode, there's a separate feedback path that drives the right channel output to the left channel's boot-strap. Since I changed the feedback resistors in the normal path from 22K to 27K, if we don't change that extra resistor, then it could create feedback imbalance in bridged mode.

    So, we just need to change one 22K resistor to 27K. The issue is, I don't know where that resistor is. My AMP-100 is buried in an equipment closet, and I can't get to it. Is there anyone that can send me fairly detailed pics of their AMP-100 circuit boards? I'll need to be able to read the reference designators, and I'll likely need images of both the main board and the rear I/O board. Sorry for any inconvenience here, guys...
    Hey Tyger, I just happen to have mine on the bench and the hood is open. I'll try to shoot some pics later today. Mark

    Leave a comment:


  • tyger23
    replied
    Re: How to turn your AudioSource AMP 100 into a real amp. (Paying it forward)

    Well, when life hands you lemons....

    I tweaked my back yesterday and that meant I wasn't outside doing oodles of yardwork today. It's hard to complain when you get out of yardwork, but it stinks being immobile. So, I spent the day tracing the PAMP1000 circuit and drawing up schematics for it. I found out a few things - Pyle copied the AMP-100 schematics almost exactly. The reference designators and some of the layout change, but they're pretty much the same.

    That also brought me to a separate conclusion - one that's important for anyone who's bridging these things with my mods (like Psychoacoustics). There's another resistor that needs to change for the bridging scenario. In the bridged mode, there's a separate feedback path that drives the right channel output to the left channel's boot-strap. Since I changed the feedback resistors in the normal path from 22K to 27K, if we don't change that extra resistor, then it could create feedback imbalance in bridged mode.

    So, we just need to change one 22K resistor to 27K. The issue is, I don't know where that resistor is. My AMP-100 is buried in an equipment closet, and I can't get to it. Is there anyone that can send me fairly detailed pics of their AMP-100 circuit boards? I'll need to be able to read the reference designators, and I'll likely need images of both the main board and the rear I/O board. Sorry for any inconvenience here, guys...

    Leave a comment:


  • Psycoacoustics
    replied
    Re: How to turn your AudioSource AMP 100 into a real amp. (Paying it forward)

    Originally posted by tyger23 View Post
    Just so I'm clear - with my audio source, the turn on thump was already there. My mods didn't do anything to improve or worsen that, nor did I try and improve that. I hope that's the same story for the others.

    Now, my cure for the turn on thump is a simple process. Right before I turn the unit on, I make sure tat neither the a bit b speakers are selected. You can do this by partially pressing one button until the other pops out, then let the partially pressed button come back out.

    This will disconnect all speakers. Then turn on the unit and give it about 5 seconds before pressing the button to connect the speakers.
    I'm sorry! I did not mean to imply that the modded Audiosource's had a problem with turn on thumps. I should have made it more clear in that anytime I come across something like that, MY remedy is to just leave it on 24/7. My modded Hafler has a pretty bad turn on thump and although it stays pretty warm, the wife hasn't noticed an increase in the electric bill and the amp hasn't self destructed, so I think I'm good.

    To continue the discussion, I have no problem leaving all my stereo stuff on 24/7. My CJ tube preamp does get turned off when I'm not using it but, my B&K St140 has been on since I bought it in the early 90's.

    I'll be interested in reading your comparisons Kevin. My guess is the Audiosource will hold it's own against the competition. Have Fun, Mark

    Leave a comment:


  • kevinr
    replied
    Re: How to turn your AudioSource AMP 100 into a real amp. (Paying it forward)

    Thanks guys , I have no turn on thump, although I think there was one before the mods. Hadn't used the amp much for quite a while so not sure.The Amp 100 was in my office for a couple of years then the basement til it developed a serious channel imbalance. There seems to be some intermittent electrical issues in the basement , maybe due to the HVAC being on the same circuit next to the water heater, washer/dryer circuit , garage door opener circuit etc.
    I just had the "pop" come one time from the amp itself on initial power up, it wasn't from the speakers , but the main board itself .
    Not loud by any means , but audible. seemed like a cap discharge ? don't know
    A little scary, but...
    Since then there's been no pop, or thump though and it sounds good.
    I'm going to take the new and improved Amp 100 upstairs and do a contrast/compare with my SET amp , The DTA-120/ Topping 21 and SMSL36 Pro just for kicks.

    Leave a comment:


  • tyger23
    replied
    How to turn your AudioSource AMP 100 into a real amp. (Paying it forward)

    Just so I'm clear - with my audio source, the turn on thump was already there. My mods didn't do anything to improve or worsen that, nor did I try and improve that. I hope that's the same story for the others.

    Now, my cure for the turn on thump is a simple process. Right before I turn the unit on, I make sure tat neither the a bit b speakers are selected. You can do this by partially pressing one button until the other pops out, then let the partially pressed button come back out.

    This will disconnect all speakers. Then turn on the unit and give it about 5 seconds before pressing the button to connect the speakers.

    Leave a comment:


  • Psycoacoustics
    replied
    Re: How to turn your AudioSource AMP 100 into a real amp. (Paying it forward)

    Hey Kevin, glad to hear your liking it! It truly is "Making a Sows Ear into a Silk Purse!" From where I sit there is nothing better than sitting down and listening to the "Fruits of ones labor".

    My cure for the turn on thump is to just leave the amp on 24/7. It certainly won't use as much power as my Hafler, and if you leave it on all the time it's ALAWYS ready to go!

    Enjoy, Mark

    Leave a comment:


  • kevinr
    replied
    Re: How to turn your AudioSource AMP 100 into a real amp. (Paying it forward)

    Plugged the Audio Source Amp 100 this morningin with a Marantz CDP and MF V-Dac to Klipsch MTM w. horn and listened to the CD of the Beach Boys' single version of their "Good Vibrations".
    Sounds good , much better than the DTA-2 that was being used . No contest, and not a fair one really.
    The DTA had some hiss in the left channel and was pretty congested in the lower freq, The Audio Source Amp 100 is much clearer.
    I'll try putting a Powervar Power Conditioner on the setup and see if the hiss on the DTA-2 amp goes away.
    The living room has it's own dedicated line for power to audio and a conditioner, but not the basement and the HVAC unit shares the same power circuit.

    Leave a comment:


  • kevinr
    replied
    Re: How to turn your AudioSource AMP 100 into a real amp. (Paying it forward)

    okey-doke
    Back from the Shack with the grease and put everything back together.
    First thing is a one time audible pop from the amp at startup, power caps maybe ?
    I've cycled the amp on and off about 4 times since and no pop.
    Then it works fine , slight hum when volume is 3/4 up
    Removed the Sony MD Walkman I was using as source and plugged in a Sony Minidisc Deck which is much better.
    Sounds good so far , the balance issue is pretty much gone so it appears it was an OEM pot issue.
    Like everyone who applies tygers mods ( thank you sir ) mentions... the top, bottom and middle are improved, the issues that made it an underperformer are absent . I'll give it more of a listen tomorrow

    Leave a comment:


  • tyger23
    replied
    Re: How to turn your AudioSource AMP 100 into a real amp. (Paying it forward)

    Originally posted by kevinr View Post
    soldered in the panasonic snap in's this am but don't have any heat sink grease compound to put back on between the heat sink and board bracket attached to U101 and U201.
    Off to one of the 2 remaining local shacks to get some . All they have in stock is the silicone version, the others are only on-line or ship to store
    The silicone version should be fine. Just make sure that when you are re-attaching the heat sink that you use a small amount of the grease on one side of that mica insulator, generally the chip side. I can't re-iterate just how important that little thin piece of clear insulator is. If that insulator is not located between the heatsink and the IC, your amp will go poof.

    Leave a comment:


  • kevinr
    replied
    Re: How to turn your AudioSource AMP 100 into a real amp. (Paying it forward)

    soldered in the panasonic snap in's this am but don't have any heat sink grease compound to put back on between the heat sink and board bracket attached to U101 and U201.
    Off to one of the 2 remaining local shacks to get some . All they have in stock is the silicone version, the others are only on-line or ship to store

    Leave a comment:


  • Psycoacoustics
    replied
    Re: How to turn your AudioSource AMP 100 into a real amp. (Paying it forward)

    Originally posted by kevinr View Post
    Thanks for the posts Mark and Tyger !
    The caps are the Panasonic snap in ones
    Tomorrow it's solder away then put it back together
    OK, ya got one day to listen, than I'm expecting a full report! :D

    Leave a comment:


  • kevinr
    replied
    Re: How to turn your AudioSource AMP 100 into a real amp. (Paying it forward)

    Thanks for the posts Mark and Tyger !
    The caps are the Panasonic snap in ones
    Tomorrow it's solder away then put it back together

    Leave a comment:


  • Sydney
    replied
    Re: How to turn your AudioSource AMP 100 into a real amp. (Paying it forward)

    Thanks, wondered how wide spread the use of that TDA7294 was commercially.
    A side note: I had seen circuits based upon these and wondered about them.
    Frankly - like you noted in other threads about circuits ( bought on-line, ebay etc ) the build quality looks very questionable.
    Poor part insertion etc.

    Leave a comment:


  • tyger23
    replied
    Re: How to turn your AudioSource AMP 100 into a real amp. (Paying it forward)

    Originally posted by Sydney View Post
    Sort of answered 1 question i had.
    Do all these amps utilize the TDA7294?
    Yes.

    Leave a comment:

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