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MiuAudio MRB Audiophile DIY HeadAmp KIt - Page 3

post #31 of 71
Quote:
Originally Posted by goodvibes View Post

That's causing the phone's Lch hot to touch the amp's r channel+ and the phone's Rch + to touch the amps ground. Since the phones are common grounded through the cable, you've got the both channels in a phasey mono connection. aR+...pL+....p-....pR+...a-. I really doubt it's the jack or a part problem. My guess would be that it's more likely a board or solder issue.

That may be but 3 of us have the problems. We have made sure that none of the solders are touching the other and what not. 

post #32 of 71

I didn't mean user workmanship but it could be that a couple solder points are done improperly on the layout. I should have just left it as a board issue to not confuse.

post #33 of 71
Quote:
Originally Posted by goodvibes View Post

I didn't mean user workmanship but it could be that a couple solder points are done improperly on the layout. I should have just left it as a board issue to not confuse.

I do not know who else has the beta test review boards besdides Tilpo,Swimsonny, and I but we 3 all have the same problem. And we are halfway across the world from each other haha.

post #34 of 71

Hopefully the fix can be rigged for the field. I built one of their earlier cheapie amps and it's noce to see them steppping up the circuit but it kinda needs to work, LOL 

 

To be clear, I'm not implying that there's anything wrong with any of the user solder work. After checking voltages, I would follow the path to see if there's a spot where it gives it up but that doesn't always help depending on the issue.

post #35 of 71
I'll try checking all the parts against the schematics that I got sent. It may be that they messed up the component numbering for a resistor, or something stupid like that.
I will probably not find anything, but it's worth a try in any case.

Little mistakes can happen, but it's not acceptable for a supposedly finished product like this.
If we find a way to fix this problem, then I'll try to tell MRB exactly what is wrong, so they can adjust their product. I want to help MRB by improving this amp just as much as I want to get this thing working so I can get a review up.
post #36 of 71
Found the issue.

You need to swap R17 and R18.

On the schematics R17 = 10k and R18 = 1k. However, in the diagram that is included with the amp R18 = 10k and R17 = 1k.
I'll contact MRB over this issue by email this afternoon. Now I need to get on with some well deserved rest, since I haven't spent much time to relax after just getting back from an intercontinental flight.
post #37 of 71

Great. Had to be something like that.

post #38 of 71

Ill warm up my equipment and put original op amps in. If it works. Review will be out in a month.

 

 

Confirmed!! Working now!

 

 

1000

 

After the review I'll swap the op amp in there with the Burr Brown 2134 and see how that sounds.


Edited by bowei006 - 8/9/12 at 5:09pm
post #39 of 71

Great Job Tilpo! Thanks!

 

Bowei I eagerly anticipate your review.

post #40 of 71
Quote:
Originally Posted by tzjin View Post

Great Job Tilpo! Thanks!

 

Bowei I eagerly anticipate your review.

It will have to wait. Another major/Critical issue popped up. The jacks. They are low quality and are extremely loose. Moving the plugs for input or headphone out will cause crackling and channel cutouts for moments of a second due to prongs not securely fitting. Both the jacks are like this and I take it the others have the same thing. This is ok/tolerable with my K422's as the cable and plug is VERY light and don't move at all. The LOD also keeps in place relatively well. But plug any regular headphone in with the larger wires and it is a huge mess.

 

I have many other reviews to get to this month. I'll see if I can get new jacks in first as it is a pain if not mess to use the MRB per it's "portable" design with such faulty jacks. 


Edited by bowei006 - 8/9/12 at 11:45pm
post #41 of 71
Corrected version of the drawing of the MRB can be found here.

They said they will include this correct version with the MRB from now on, so it looks like potential buyers will not be facing the issue we did.
post #42 of 71

Awesome. That should be plenty of fun swapping the resistors. Waiting on the new parts and i will get on it! Review will be in roughly a month as well as have a fair few lined up!

post #43 of 71
Tilpo. Have troubles with the jacks like i said above. Move your headphone cable near the headphone out base around. See if you get the same
Problem
post #44 of 71

Okay. Got a new kit. Soldered everything to the new sheet. No power light and no sound?????

post #45 of 71
Quote:
Originally Posted by Swimsonny View Post

Okay. Got a new kit. Soldered everything to the new sheet. No power light and no sound?????

Well, that could be caused by just about anything.

I'll be blunt and say: is the battery fine?
Also, did you put in the battery clips the right way?


Otherwise you can measure current. Put the battery only on one of the clips, and connect the other polarity to one probe of the multimeter, and the other side to the other battery clip. If you don't understand what I'm saying, then I'll make a diagram.

Also, try uploading a picture of the up and underside of the board. Perhaps you put a component in some wrong way.
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