Members mikjwilli Posted January 20, 2010 Members Share Posted January 20, 2010 Hey Guys- I recently picked up an ADA Microtube 200 power amp off of ebay. The amp seems to be working fine in stereo mode, although the volume seems to be a bit lower than expected. However, in bridged/mono mode, there's barely any volume at all and when I turn up the volume on the preamp (Digitech GSP 1101), there's nothing but severe distortion/static. I'm considering filing a claim through ebay. I'm also trying to get the seller to pay for the repair as an option. If there's an easy fix, I'd like to keep it as it is a great sounding amp (in stereo anyway ). The preamp tubes seem fine as I tried to switch them with no change. The output in bridged mode is 8 ohms and I used several 8 ohm cabinets as well. Thanks in advance- Link to comment Share on other sites More sharing options...
Members jwlussow Posted January 20, 2010 Members Share Posted January 20, 2010 Are you using the bridged out connection or the stereo outs? You are only hooking up to one 8 ohm speaker at a time, right? Link to comment Share on other sites More sharing options...
Members mikjwilli Posted January 20, 2010 Author Members Share Posted January 20, 2010 Are you using the bridged out connection or the stereo outs? You are only hooking up to one 8 ohm speaker at a time, right? I'm using the bridged/Mono out to a single 8 ohm cabinet. Link to comment Share on other sites More sharing options...
Members agedhorse Posted January 20, 2010 Members Share Posted January 20, 2010 Have you read the manual? Exactly how are you hooking up the speaker to the two outputs (I mean exactly... details and all) Link to comment Share on other sites More sharing options...
Members bigjd Posted January 20, 2010 Members Share Posted January 20, 2010 Go herehttp://www.adadepot.com/forum/index.php?PHPSESSID=f302ef3cf19b5231652425b338834bea&These guys are the best at ADa GEAR. Link to comment Share on other sites More sharing options...
Members mikjwilli Posted January 20, 2010 Author Members Share Posted January 20, 2010 Go herehttp://www.adadepot.com/forum/index.php?PHPSESSID=f302ef3cf19b5231652425b338834bea&These guys are the best at ADa GEAR. I posted a message there. Still waiting. Link to comment Share on other sites More sharing options...
Members mikjwilli Posted January 20, 2010 Author Members Share Posted January 20, 2010 Have you read the manual?Exactly how are you hooking up the speaker to the two outputs (I mean exactly... details and all) I have. If you click on the attached, I ran the preamp into the mono in in the middle/top and the middle/bottom jack to an 8 ohm 1x12 speaker cab in mono bridged setup. http://i101.photobucket.com/albums/m60/mikjwilli/guitar/ADARear.jpg For stereo, I did the same, but I used the last column of jacks on the right (channel A). Link to comment Share on other sites More sharing options...
Members bigjd Posted January 21, 2010 Members Share Posted January 21, 2010 Okay does both channels work independantly?Input A is putting out for output A.Input B is putting out for output B.I'd put a jack in input A with no signal on it to break the switch and put a signal through input B to see if they work individually, in stereo.So there would be no signal on output A and whatever your feeding it on B. I found your post on the ADA board,sometimes it takes awhile there's alot of people over in Europe on that board. Link to comment Share on other sites More sharing options...
Members agedhorse Posted January 21, 2010 Members Share Posted January 21, 2010 Looks correct. There may be a problem with the internal normalling switches inside the jacks. Just to be sure though, verify that the mono input doesn't need a balanced signal in order to get a bridged mono output. Link to comment Share on other sites More sharing options...
Members mikjwilli Posted January 21, 2010 Author Members Share Posted January 21, 2010 Okay does both channels work independantly?Input A is putting out for output A.Input B is putting out for output B.I'd put a jack in input A with no signal on it to break the switch and put a signal through input B to see if they work individually, in stereo.So there would be no signal on output A and whatever your feeding it on B.I found your post on the ADA board,sometimes it takes awhile there's alot of people over in Europe on that board. Both channels are working independently and seem fine. I didn't have to put a jack in channel A. Channel B worked without. Link to comment Share on other sites More sharing options...
Members mikjwilli Posted January 21, 2010 Author Members Share Posted January 21, 2010 Looks correct.There may be a problem with the internal normalling switches inside the jacks. Just to be sure though, verify that the mono input doesn't need a balanced signal in order to get a bridged mono output. Same thing with a balanced 1/4 cable. Thoughts? Link to comment Share on other sites More sharing options...
Members trevcda Posted January 21, 2010 Members Share Posted January 21, 2010 For anyone it may help, the schematics can be found here: http://www.adadepot.com/adagear/gearpages/poweramps/ADA-Microtube-200.htm Link to comment Share on other sites More sharing options...
Members agedhorse Posted January 21, 2010 Members Share Posted January 21, 2010 Input circuitry is on a corrupted document. Can't tell what they are doing. Link to comment Share on other sites More sharing options...
Members trevcda Posted January 22, 2010 Members Share Posted January 22, 2010 Input circuitry is on a corrupted document. Can't tell what they are doing. Contacted Admin. Hopefully he can fix it or send me a scan. Link to comment Share on other sites More sharing options...
Members mikjwilli Posted January 22, 2010 Author Members Share Posted January 22, 2010 Thanks everyone- I decided to bring it to my tech, who's a pretty reputable tech. He confirmed both sides were working OK. As it turns out, there was a problem with an internal switch, which he was able to repair. Link to comment Share on other sites More sharing options...
Members jwlussow Posted January 22, 2010 Members Share Posted January 22, 2010 Excellent. Glad it worked out for you. Link to comment Share on other sites More sharing options...
Members agedhorse Posted January 22, 2010 Members Share Posted January 22, 2010 Thanks everyone-I decided to bring it to my tech, who's a pretty reputable tech. He confirmed both sides were working OK. As it turns out, there was a problem with an internal switch, which he was able to repair. That was the most logical reason based on how the input stages are configured. Link to comment Share on other sites More sharing options...
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