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Hello all. It has been some time since I posted on here. Some will remember me from the bias mods I was producing while back. I have since closed down the business due to lack of time. I work a full time job and quite honestly I was getting a ton of overseas orders through my website which just...

I have completed the bias probe for use with combo amps or really any amp for that matter and wanted to share a few pics. You can also check the plate voltage with this probe as well which is something you cannot do with the conventional probes. I am going to make these available so anyone...

I am in the process of making a bias probe that will cure your issues. This came about as a request from another Roadster Combo owner and I agreed to build it. I just have to test it and source some good wire for it and I will make them available to all. I will also post a pic of the prototype...

Bob, I suppose if you want it to fail at a lower resistance then the trim pot would be the one to change. A 50k resistor with a 50K trimpot would fail around 100K. Which is around where you have it now. THe only disadvantage is you won't be able to bias any hotter then that. By going back to...

No problem Bob. That was my main concern is with a pot failure the full pot resistance and the 50K is too much. Other than that I see no problem. Keep in mind there is next to no current flowing. Only around .002mA so the 1/2 watt cermet pot is working no harder then the stock resistor that was...

Bob, Glad you recieved the replacement and everything worked well. Just wanted to clear one thing up. I used a 22k and a 100k trimpot which adds up to approx the original value of 120k. Lowering the resistance equals more bias voltage and cooler running tubes. Increasing the resistance 50K and...

I have gotten almost identical John Petrucci tones (from his Mark V Video on Mesa"s website) with my roadster on channel 4 Modern mode by using the parametric eq in the loop on my G major. I chose three bands that were closest to the mark v's eq. If I remember correctly I boosted 79.43hz, cut...

Bob, I decided to just send out a new kit already done. This way all you have to do is install and not worry about swapping components. It's my way of saying thanks for your willingness to experiment. As per our phone conversation you were aware that the kit may or may not work without some...

Bob, I have 100k trimpots that fit the board as well. Since you bought the kit I can send you out a 100k trimpot and a 22k resistor free of charge. This way you can swap it out and put the 33k back in and use your kit in place of the 120k. Just let me know what you want to do. Thanks John

I prefer 12 vdc fans. They are quieter and there is no extra noise carrying wires added to the amp. I power mine off the 6.3vac winding. Use 2 1n4007 diodes to rectify the ac to dc and a 470uf capacitor to smooth the voltage and you end up with around 8vdc. This runs the fans slightly slower but...

I just thought everyone here would like to know I took the time to contact Mesa Boogie regarding their bias supply. The tech I spoke with informed me that these amps definatly do run hot and reccomend their coolest running tubes (red). The method they use for cooling the bias down is the same...

Channel one signal flow starts out from input jack to V1A. From V1A to channel 1 tone stack, then channel one gain pot and then to inout 0f V1B. Since all channels use those same tubes that would rule them out. My guess would be a broken wire or component in the tone stack or on the gain pot or...

We do make an adjustable bias mod which consists of a small pcb board that houses a trim pot and a series resistor. It comes with complete instructions and should work fine on the DC3 and DC5. Some customers even mounted theirs external for biasing without pulling the chassis. They have been...

I just want to point out with the bias settings, nothing is really etched in stone. Most agree that somewhere around 85% is max. Alot of people won't go over 70%. The point is if running a little hotter sounds better to you and your tubes are not redplating then you should be ok. It would only...

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Trev, If you or anyone has some suggestions for me to add to the instructions then please share. Sometimes us techs assume that people know some of the basic things. My goal with these kits are to make them as easy and painless *** possible. I'd be more than happy to revise the instructions to...

Trev, If you or anyone has some suggestions for me to add to the instructions then please share. Sometimes us techs assume that people know some of the basic things. My goal with these kits are to make them as easy and painless *** possible. I'd be more than happy to revise the instructions to...

Thom, Good catch. I did mean the Lonestar Special and I edited the original post. Hopefully somenone out there has the schematic. Thanks John

I'm once again offering a free bias mod kit to the first person that can get me a copy of the lonestar Special schematics. Simply email them to [email protected]. Also include your shipping info and amp you want the kit for and I'll get it shipped our right away. Thanks John

Trev, That's so good to here. No need to appologize. Your frustration was understandable. I just want you and everyone to know that once you buy a product or service from me your not ever on your own. I am always here to help in every way possible. Thanks again to everyone John