Easier maintenance ARCVT100mkII or VTL mb125

Hi Alun,
I think IG40 comment to check "mycollins.net" site is a great idea, very interesting and has correct proceedures.

Bias the power tubes in the VT-100 is straitforward, adjusting the input/driver tubes is a little more interesting and will require some basic electronic's backround. I would not try this proceedure without two volt meters.

It is my understanding, ARC recommends adjusting the driver/input tubes at the same time you make a power tube change with the VT-100 original and Mark 2 units.

If you were to purchase a second hand VT-100 amp, several ARC dealers and other service centers can correctly complete this tube replacement/bias service without sending the unit back to ARC. Maintenance should not be to difficult but may require a local Tech for assistance.
Good Luck,
Steve

That is incorrect. There is no requirement or reason to rebias the input tubes when you replace output tubes. The bias control on the output tubes has no effect on the input & driver tubes. ARC recommends replacing the input & driver tubes after two replacements of output tubes. In reality, the input & driver tubes can go longer than two sets of output tubes, probably three sets before their life is beginning to wane.

I own the VTL MB-185's. Biasing of the output tubes is accomplished via individual trimpots accessible through the top panel once the tube cage is removed, and adjusted using a narrow flathead screwdriver. Each trimpot is associated with its own meter probe receptacle, the other probe being attached to the 'negative' speaker terminal. The only difficulties, if you want to call them that, are that you must own or purchase an appropriate multimeter (selection guidance is given in the manual), and the trimpots themselves tend to be quite touchy, responding somewhat imprecisely to very small turns. I've used easier (Conrad-Johnson), but there should be no problem doing this operation yourself. As far as retubing goes, VTL runs the tubes conservatively and they should last a long time as a consequence. Tube types are not exotic, rare, or overly expensive, though as usual, expect to pay a premium if you choose to retube through the manufacturer instead of buying from a tube retailing specialist.

What fantastic responses from all!!! I thank you for your input and advice. It seems a lot of people own the ARC amps and have mixed reviews regarding their upkeep. Although I've contacted a couple of people with the VTL's they seem a little more staight forward and user friendly. I will check out the "Collins" website that everyone suggested and make sure. Unfortunatly there are no AR/VTL/Rogue dealerships in the local so I cannot hear them to make personal judgements. Therefore I must rely on fellow Audiogoner's for their input. Thanks a bunch

Alun

All of the above notwithstanding, I'm pretty sure the biggest deciding difference between your contenders will be sound, not maintainance. Search the Audiogon archives for more - related questions have been asked before.