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Hi there everyone,I've taken a long hiatus from this group and my tube gear in general, trying to sort out other matters, etc. Recently (for one thing), I had to move to another location (my tube gear included).
My stereo problems actually started shortly BEFORE I made the move. I noticed things starting to distort. I'd be playing familiar records and they'd kind of start "clipping" at all volumes. Something was wrong! I switched out the GZ34 in my Dynaco ST70 with a NOS Mullard. I thought that solved the problem, but I guess I was wrong...
Currently (and for the past several weeks), I've run into further problems. Get this! While I have no Stereo/Mono switch on my Amp or Preamp, I've noticed that there is no such thing as stereo separation anymore! Both channels are one and the same and they are all distorted. Songs with a sax in only one speaker now have the sax in BOTH speakers and the sax sounds like sh*t! I just finished rebuilding my Stereo 70 AGAIN!! I replaced all the tube sockets with a firmer gripping set of ceramic gold plated ones. Everything has been checked and then checked again. All wiring and connections are more than succint! I know I've got it right!! I haven't changed anything since before it started acting up and the tube sockets have all been changed with extreme care.
There is a constant static that crackles in both speakers which is quite audible. It gets louder when I raise the volume. I tried swapping the phase inverter tube on the triode electronics board, but that did not help at all. Currently, I've got a brand new (NOS) Mullard GZ34 in the rectifier spot. I'm using JJ E34L's for the Outputs and GEC Mil-spec EF86 variants. Everything in the Dynaco has been checked and then checked again. I don't think this is a tube problem. Furthermore, all connections (right and left IC's) are correct in "in phase." Same goes for the speaker cables.
I could understand the static/crackling in the background maybe as a bad resistor or something. But now that the left and right channels have begun to merge and distort, I know the problem lies elsewhere. I have been avoiding the Preamp because I thought it was all set - Perfect and Complete if you will!
I am going through audio hell here and have no solutions in mind.
Maybe the problem lies within the Mac Preamp (also completely rebuilt and doing fine `til just recently... Maybe certain resistors should have been 1 Watt and I used 1/2 watters? But why would both channels merge together? I just can't figure it out! I am extremely distressed and really don't know what to do. I don't understand how this could have happened and am very upset over it!There is the same no channel separation whether the CDP (An Ah! Tjoeb 4000) OR the Turntable (SOTA Moonbeam) is in use. Therefore, the sources are not at fault here. I've played the same tracks on each, which I'm quite familiar with and the same thing happens... I think the problem lies within either the Amp or the Preamp, but I don't know how to figure out which one it is and solve the problem.
I know this might seem like a lot to take in. I am at a loss here. I have been hanging my head in shame for the past several weeks over this dilemma and see no end or solution in sight. These (My Mac Pre and my Dynaco ST70) are my pride and joy. They have been taken from me and I want them back!!! Please help me to narrow down my problem so that I can fix it. I cannot do it alone.
I thank you most sincerely for reading this and thank all those for there help in advance. It would really mean a lot to me to get some support with this. I am very distressed and my tube gear is sleeping once again...
Thanks a lot for your help!
Sincerely,
Follow Ups:
If your volume control affects the static level, then the problem is not in your ST-70, since it comes "downstream" from the volume control.Chris
Read Kurt Vonnegut, Tom Robbins, and Charles Bukowski.
Sorry to hear of your difficulties... the MX110 was the most frustrating component I ever owned; I didn't realize so much could be crammed into a chassis! With the amp off, pull one input cable from the front of the amp and power up; if you have sound in both channels, the problem is the stereo/mono selector on the amp. If you have access to a portable CD player or any source component w/ a volume control, plug it directly into the amp; this will ferret out the culprit. I recall my MX110 would behave as you describe if one of the selector switches or source knobs was lodged in between positions even slightly; manipulate every rocker switch and knob on the unit and then firmly set them to your preferred settings. Also, the gain knobs on top of the MX110 can be problematic; rotate them a few times and then reset. The key to cracking this is to isolate the components from each other; if you have a classical CD or other "soft"/low volume disc, you can briefly plug your CDP directly into the amp; I wouldn't recommend this except for brief troubleshooting, and only if you have no source component with a volume control. You could also make a passive volume box with Radio Shanty potentiometers to shave off the output of your CDP; two jacks for in, two for out and a pair of 25k linear taper pots will serve. It'll sound a little strange, but will allow troubleshooting. You could also increase the input loader resistance to reduce gain... to allow use of your Ah! in troubleshooting. Hope this helps! I had a PAS3X that was so vexing that to prevent a stroke I had to pour Sterno on it, tie it to my bumper, light it up and drag it behind my car until it crumbled. Ah... good times. Chris
Brian do I remember you are in Seattle? If so I have a spare MX110 I am not using in perfect working condition if you want to swap it in for troubleshooting purposes....
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