M501 bridging-have I lost my mind?

[jrgoswick]

I'm a fan of the little Onkyo M-501. This ISN'T as bad an amp as most think. A few power supply upgrades(power cord, caps, bridge, ect). and it'll get with it. I'm considering getting another one and using a Hafler DH-222 bridging module type device. I can etch the PCB's myself, and I've reviewed the schematics of BOTH amplifiers(M-501 and the DH-200). They're both common ground, so I don't see any reason why this won't work. So have I lost my mind or do I need to post pics of it when it's completed?

[concealer404]

I agree that it's not as bad as most people think. :) I enjoy my M-5150.

As for bridging, as is, nope, can't.

But if you've got the ability to modify it to that extent, go for it!

PS: Want to mod mine?

[jrgoswick]

As they sit, you're correct. You CAN NOT do it. HOWEVER the Hafler 222 card is a phase inverter-ie it runs one channel 180 degrees out of phase. SO instead of one channel doing ALL the work, one channel soaks the + side of the wave and the other the - side. This is what is known as a BTL configuration(bridge tied load). You use the left positive output to the positive on the load and the other positive to the negative on the load. If you consider this READ ABOUT IT FIRST!

As for modding these amps, the FIRST thing you can do and notice a MAJOR improvement-ditch the factory power cord. I'm currently using a piece of 12/3 SO with a Hubbell plug-wired straight in. My power supply also consists of an upgraded bridge rectifier(600V 35A) on a stand alone heat sink. As for caps, a pair of Cornell Dubilier's at 80V and 35000uF-for a total of 45000uF on the rails. Bypassed of course with 3.5uF polyesters.

The M-501 is a class B amp(it DOES swing positive and negative rail). This isn't a bad design(most high end amps are based on it). It just needs a little massaging. I don't know about your amp, but mine had CRAPPY internal wiring. Time for an upgrade-also time to test your skillz! My M-501 WAS using 22awg for busing stuff together. Mine is using Dayton 14awg for MOST of the board to board stuff. Using Dayton 12awg for the bridge, and 10awg(which is what I'm also using for speaker cables to my M12's) for the caps to the DC bus. This will improve the transient response of the amp(low end is tighter and mids are A LOT TIGHER). Also-upgrading your output terminals is a MUST(would have just soldered mine straight, but the wife likes to move stuff around). Another thing is bypassing all the protection crap and what not-YOU NEED TO KNOW WHAT TO LISTEN FOR OR YOU'LL TOAST YOUR SPEAKERS!!

I like these so much I bought my father one for his M10's. He was using an HK770(which is now driving his tweets). We(my father and myself) are currently deciding on what to do about the amplifier section itself. Considering the bridging thing for mine, he's using a Lindquist active XO. Upgrading ALL components in the signal path, biasing resistors, ect.

A LOT of people talk smack about these little amps. BUT if you get one on the cheap and know what you're doing you can really make these things sing. I do it because it's a VERY ENJOYABLE hobby, it keeps me out of trouble(until my wife see the bank statements), and the whole family can enjoy it.

If you've got questions or suggestions feel free to email me, or better yet-POST IT!

[jrgoswick]

As they sit, you're correct. You CAN NOT do it. HOWEVER the Hafler 222 card is a phase inverter-ie it runs one channel 180 degrees out of phase. SO instead of one channel doing ALL the work, one channel soaks the + side of the wave and the other the - side. This is what is known as a BTL configuration(bridge tied load). You use the left positive output to the positive on the load and the other positive to the negative on the load. If you consider this READ ABOUT IT FIRST!

As for modding these amps, the FIRST thing you can do and notice a MAJOR improvement-ditch the factory power cord. I'm currently using a piece of 12/3 SO with a Hubbell plug-wired straight in. My power supply also consists of an upgraded bridge rectifier(600V 35A) on a stand alone heat sink. As for caps, a pair of Cornell Dubilier's at 80V and 35000uF-for a total of 45000uF on the rails. Bypassed of course with 3.5uF polyesters.

The M-501 is a class B amp(it DOES swing positive and negative rail). This isn't a bad design(most high end amps are based on it). It just needs a little massaging. I don't know about your amp, but mine had CRAPPY internal wiring. Time for an upgrade-also time to test your skillz! My M-501 WAS using 22awg for busing stuff together. Mine is using Dayton 14awg for MOST of the board to board stuff. Using Dayton 12awg for the bridge, and 10awg(which is what I'm also using for speaker cables to my M12's) for the caps to the DC bus. This will improve the transient response of the amp(low end is tighter and mids are A LOT TIGHER). Also-upgrading your output terminals is a MUST(would have just soldered mine straight, but the wife likes to move stuff around). Another thing is bypassing all the protection crap and what not-YOU NEED TO KNOW WHAT TO LISTEN FOR OR YOU'LL TOAST YOUR SPEAKERS!!

I like these so much I bought my father one for his M10's. He was using an HK770(which is now driving his tweets). We(my father and myself) are currently deciding on what to do about the amplifier section itself. Considering the bridging thing for mine, he's using a Lindquist active XO. Upgrading ALL components in the signal path, biasing resistors, ect.

A LOT of people talk smack about these little amps. BUT if you get one on the cheap and know what you're doing you can really make these things sing. I do it because it's a VERY ENJOYABLE hobby, it keeps me out of trouble(until my wife see the bank statements), and the whole family can enjoy it.

If you've got questions or suggestions feel free to email me, or better yet-POST IT!

As for modding yours-how about you do it yourself. Ask questions, they will be answered. Do it and take pride in your hobby, because nothing is as bitchin' as your friends saying "Man how'd you do that?"!!!!!!!!!:D:D:D:D

[jrgoswick]

I don't know how that happened guys. Guess I'm enjoying my day off!;)

[concealer404]

Honestly... i've been trying to replace mine for awhile, but i haven't been able to find anything better unless i spend some pretty serious coin. (At least for my budget.) I moved AWAY from Adcom amps to this thing. I even tried an XPA-2 in an effort to move it out of here. That didn't go well.

I may pick your brain if i find some extra cash here shortly. I've got another amp in rotation right now, so i'm free to mod my Oinker if i can do it quick.

[jrgoswick]

Will it sound like Krell? Probably not-BUT it will sound better. Pick my brain all you wish, I as well as yourself will enjoy it. My current M501, I paid about 135 shipped. It's got about 125 in parts and labor is unmeasurable. I LOVE the way it sounds. Like you I'm on a budget. I've also got a fair grasp and understanding of electronics-hence the mods. They're not hard to do at all, and you'll learn a bit. BUT for your 5150(that right?), you MUST get a service schematic. Again, if you've questions-JUST ASK. As for modding yours, I'll help-but YOU have to do the work. Sound fair?