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

[Psycoacoustics]

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

[tyger23]

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

Mark - perfect. I think I can see the offender already - RL1 (the resistor nearest the grey bridging cable). Can you measure that RL1 resistor to see if it's 22K (or just check the color codes). If it is 22K, then that's the one that needs to change to 27K in bridging mode. You should be able to measure the resistor in-circuit if you make sure the switch for bridging is set to "normal".

THANKS!

Oh - and fantastic job on your reworks. They look great!

[Psycoacoustics]

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

Thanks for the compliment! Even a blind squirrel finds a nut now and again.

Yes, it measures 21.9k ohms and the colors are Brn red blk red red.

I wish I could help you test your theory but, I gave away one of the two I had. Although, a funny thing happened at my Menards. I went looking for the Pyle and it turns out they had one Pyle, and one Audiosource, both priced at $69.

After thinking about it,,,,, I left without them. I'm enjoying my Hafler and really don't need another amp.

If however anyone else reading this would like me to pick one of them up for them and ship it off, I'd be happy to. I'll even offer to mod them if anyone is interested, all ya gotta do is ask. Oh yea,,, and send me a check for the amp and mod parts. The labor would be free. Later, Mark

[kevinr]

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

I've been using AS amp 100 Line 1 since the mods, and just for grins tried Line 2 , Right channel fuzzy . Hm ?
Previously I had always used Line 2 only, and there was something funky going on between the channels . Then it just sat on the shelf for a while
Line 1 sounds very good though after the auto switching circuit mods by Tyg.
I then inserted my Little Dot MkII+ tube preamp ( upgrade w/ NOS tubes ) in front of the Amp 100 and it sounds even better.

[drewdigs]

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

Hi tyger23, I've had an AMP-100 for about 3 years now and am going to try your modifications out for myself. I've done recaps on audio mixers and other amps so I feel pretty comfortable about most of the work here. For about forty bucks and a weekend I figure it's worth a shot; if all else fails I was probably due for an upgrade anyways!

What I wanted to ask you was your thoughts on the possibility of modifying the relay circuit that normally switches on/off line 1 for manual control of the relay by a switch, so that you'd be able to do true input 1/input 2 switching. That's the one feature that I think would push the potential of this amp over the top for the price.

[tyger23]

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

What I wanted to ask you was your thoughts on the possibility of modifying the relay circuit that normally switches on/off line 1 for manual control of the relay by a switch, so that you'd be able to do true input 1/input 2 switching. That's the one feature that I think would push the potential of this amp over the top for the price.

It should be fairly easy to do. You'll need a SPDT switch to do it. Basically, locate the relay and specifically the 2 pins that are set away from the other 6 pins. Those 2 pins are the control signal. One pin will be hard-tied to ground. The other will be connected to a resistor (should be a 47-ohm value).

Remove the resistor. Once you've removed the resistor, you'll need to wire the switch to provide that now disconnected realy pin with either GND or +12V. You can obtain the +12V from either the 6-pin connector that leads to the main board, or at one of the two larger bulk capacitors near that connector. Just make sure to use a multi-meter to measure the voltage at the point you're tapping into. You don't want to accidentally grab the -12V instead.

[drewdigs]

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

Hi tyger23, thanks for the response. Seems pretty straightforward then. Just to confirm; if I do that mod as you described, and I have the switch selected to input 2, that will prevent the amp from switching to line 1 even if there's a signal on the input unless I manually throw the switch to input 1? Sorry to be redundant just want to make sure I've got it right.

Also just wanted to get your opinion on a switch I dug up: LINK. I'm thinking I want to mount this right above the A/B speaker selectors; seems like good of a place as any. I looked at rotary switches too but can't find anything that matches the actuator lengths of the volume and balance pots... so I think I'd rather go with a slide switch instead. I'll have to find someone to cut the panel but there should be someone local that can do it. I'll post some pictures when I get to that point if anyone is interested in seeing it.

[tyger23]

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

Hi tyger23, thanks for the response. Seems pretty straightforward then. Just to confirm; if I do that mod as you described, and I have the switch selected to input 2, that will prevent the amp from switching to line 1 even if there's a signal on the input unless I manually throw the switch to input 1? Sorry to be redundant just want to make sure I've got it right.

Also just wanted to get your opinion on a switch I dug up: LINK. I'm thinking I want to mount this right above the A/B speaker selectors; seems like good of a place as any. I looked at rotary switches too but can't find anything that matches the actuator lengths of the volume and balance pots... so I think I'd rather go with a slide switch instead. I'll have to find someone to cut the panel but there should be someone local that can do it. I'll post some pictures when I get to that point if anyone is interested in seeing it.

1. Your understanding of the operation of the circuit is correct. It shouldn't switch unless you manually flip the switch.
2. The switch you linked to should be fine. Any SPDT would work. You're going to have some trouble getting that slide switch to fit on the back panel. You'll run into a clearance issue with the way the rear I/O board is mounted. To me, you're better off mounting it on the front panel. You can use a simple toggle switch (which can be mounted by using a simple round drill bit). I'd probably go for this one:

http://www.digikey.com/product-detai...2370-ND/378839

[pfrakes]

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

I have to admit, these mods improved the amp's performance more than I expected. I'm quite happy!

However, I took the liberty to cut the mods down to the bare minimum. I did not change out the op amps or their power supply caps, and I did not do any power supply mods. I also did not change out the volume or balance pots, but that is something I still might do.

The rest of the mods, though, made an amazing difference to what I thought was a very ordinary amp. Thanks for taking the time to write them out and post them!

I used caps that I already had on hand, which were Panasonic.

[drewdigs]

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

Just a quick update; I'm still waiting for Mouser to get one of the Bourns pots in before they ship my order. Unfortunately the estimated ship date isn't until 9/21... :( Once they're in and I get things rolling I'll take some pictures.

tyger23, have you ever had a look at the Dayton APA100? It looks to be an almost exact copy of the AudioSource/Pyle amps that you've modded. There are some pictures of the guts on PE. I only ask because if this mod goes well I'd like to get another one of these amps and mod it as a nice holiday gift for a family member. I notice the AudioSource AMP-100s being sold now have some goofy branding on them, which I don't prefer aesthetically, and the Pyles are, well... Piles. If its pretty much the same amp/circuit then I'd probably pick up the Dayton and give it a shot but just wanted to see what you thought first.

[tyger23]

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

I addressed the question about the Dayton APA100 in my thread regarding the Pyle mod. I think the Dayton mirrors the Pyle, but I can't confirm it. It looks like all the components are in the same places, but I can't confirm that the reference designators will be exactly the same. In other words, R10 on the Pyle may be R130 on the Dayton. This might lead to some confusion when trying to do the rework.

I would follow the mouser cart for the Pyle if you purchase the Dayton.

The Pyle represents a pretty good value for the money. The circuit is virtually identical to the AudioSource, but the chassis is lesser quality. So, if you're willing to put up with cheaper materials and finish on the case, you're getting the same amp.

[kevinr]

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

Mr. Frakes ;
My dos centavos I changed out the volume and balance pots on my Audio source Amp 100 per Tygers mods and IMHO they are well worth it . The OEM pots just aren't that good .

[Justinlwtx]

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

Well I finally got all of my components in, so I reworked 2 of these today. I did one with all Nichicon capacitors and components in the cart posted in this thread. The second one, I substituted Panasonic FC series capacitors with the same values. Both amps were tested with my B&W 685 speakers bi wired with 14awg cable.

I've always been a Nichicon fan, likely born from the couple of Krell amps I started this hobby with, and they didn't disappoint me here either. The Nichicon amp was smooth, and laid back. Seemed to take the edge off of my digital music and made it easy to listen to. As described before, almost tube-like. Bass is smooth with a good amount of punch. Vocals are loud and clear, highs never seemed to get harsh.

The Panasonic amp sounded great as well. Slightly more detailed up top, bass seemed tighter, vocals were a little lacking in depth. Unlike the Nichicon amp, this one can get harsh at higher volume playing rock and heavier music. Played at a reasonable volume I could enjoy this setup, but paired with the 685's it would likely be fatiguing after a while.

I also kept a third amp completely factory for comparison, and the differences were drastic from where they started. I believe for my taste the Nichicons are a better (and cheaper!) choice. I also noticed that both amps sounded better after a couple of hours play. Currently I have the 685's paired with the Nichicon amp, and a pair of Polk R50's on the Panasonic amp playing overnight to burn things in. I had a slightly audible hum from both amps in the beginning above 1/2 volume, but it has nearly gone away in both.

Overall, I'm glad I took this on. I now have 2 zone players paired with Raspberry pi 2/hifiberry DAC streamers that are ready to play at any time from an app. Exactly what I wanted, with much bigger sound than I could have imagined.

[bullittstang]

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

First off, HUGE THANKS to Tyger!!!!! I bought this amp off CL about 7 months ago and I actually thought it sounded pretty good, but I have never actually had a component amp, just AVR's.
So I when found this thread in April-May I figured what the heck, so I ordered all the parts (ordered the "shopping cart" except I had to substitute a different 25V 470uF Caps, the originals were back-ordered for 2-months). So for the substitute Cap's I ordered one step below Tyger's suggestion with the help of an extremely helpful Mouser Rep. she helped me sub in the UKT version instead of UKW. I also ordered Tyger's suggested Panasonic snap-in Power Supply Caps that actually fit under the cover, and they worked out perfectly.
Well got everything on 6/20/2015, so as you can see it has taken me 2-months to get this project started. But very worthwhile, just listening to them with some Quarks on my desk and it sounds great! Will expect it to open up a little bit more after some use, but even now it sounds very clear and seems to play a little louder (that might be good-ole' day syndrome), because I honestly haven't listened to it for 2-months.
Either way, I had no experience removing or soldering on-board components and I did it, without any "magic smoke", so that means just about anyone "handy" could do this upgrade.
Bottom line - $40 Amp from CL + $51.61 in Mouser parts and Started on Saturday, so two days and a total of about 7 hours labor = one very nice amp, that punches way above my $91.61 investment.
Thanks again Tyger, you certainly "paid this one forward"!

[Justinlwtx]

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

Well after spending a few days with the amps, I've noticed that there is an audible low hum in the background of both. With no input connected, the hum is present and gets louder past 12 o'clock. It also increases if the volume is turned to minimum. Has anyone else experienced this? As I said it's present in both reworked amps, and can be heard across the room with volume at any level.

The new stock amp I have has a hum as well, but much lower and constant throughout the volume range.

EDIT* After experimenting a little more, the hum is only louder than the stock amp when a source is connected (I've tried two sources, different RCA cables, input 1 and 2). The hum changes when the relay click is heard, when connecting to inputs or pushing play/pause on source.