2. amps-preamps
  3. 150254-46

Need advice in Audio Research Classic C-60Amp

I just purchased a classic C-60 to pair with my old Vandersteen 2CE’s.

Right now I’m just using Blue Jeans biamped speaker cable terminated in spades on the amp end. The classic only excepts wire that are screwed in on the back of the app. This means I’m going to have to cut the ends off the spades, and because it is Bi-amped I’ll then have two positives wires and two negatives  going to one channel. 

So my options are to just not use one of each color (one red one black) or twist the two reds together and twist to blacks together.  My question is what is the best way to attach the wire to the amp. Do I need to buy a different type of termination or is it just the bare wire that gets screwed in. And how do you think I should go about doing this with the wire I have. 

Also one follow-up question, if I just cut one black wire and one red wire from the spade, and tape them up, is there anything I should be worried about, sonically?
last_lemming
dweller's avatar
dweller
3,735 posts
 
Looks pretty slick! I always let the tech replace/rebias the power tubes so no first-hand experience. $50 will get you a nice multi-meter so you "makes your choice and you takes your chance" but I can’t see why this wouldn’t work. Keep in mind, this device will tell you your current bias but if they are high or low, you'll still need to find the trim pots and use a screw driver to make any adjustments. BTW, did you get the owner’s manual for the CL-60? It may have info you can use.
last_lemming OP
630 posts
 
I got the original manual, and even the original sales brochure, but the manual only says how to do it, no pictures, and the description is only basic.

but if the device above eliminates the need to stick probes in dangerous places and all I have to do is turn a screw that would help immensely.
djohn
64 posts
 

I am glad that you talked to Scott Frankland as I advised.

oregonpapa also made some good comments to illustrate how good this Amp is. I did not change the Power Cord with an IEC and I did not change the RCA’s.

Instead, I put my money into a Mod performed by Scott that eliminated the Auto Bias. What he did was drill 3 Ports on the base at each side (Black Steel Base) and also installed 2 Trim Pots on each side at the back so they are vertical standing. For me to Bias this Amp now I just stick 2 Voltmeter Probes into each respective port and I can adjust the Bias myself. Brilliant.

Recently, he changed the 4 Filter Caps with the Red Caps in the middle of the Circuit Board & also installed some V-Cap Copper Foil Teflon Caps where they matter sonically on the Circuit Board. This has elevated the performance and it was well worth the money.

As you are attempting to save money you are proceeding the wrong way. To Bias this Amp it has to be on for a minimum of 30 Minutes and you adjust it with the bottom plate removed.

Unless you know what you are doing there are Lethal Voltages at play here while you are poking around.

You need to stop and think about Shipping this Amp to someone that is highly skilled.

dweller also made a good comment that the Tubes that are in it could be OK for the Short Term since Upscale is familiar with Audio research. But what specifically was done before the Sale? Only certain Tubes can be used in this Amp and you stand the risk of blowing a Resistor that is Soldered to the Circuit Board.

Like oregonpapa, I have owned this since New and it is well worth modding. Scott has been the only Tech that has touched this Amp previously, recently, and will do so again in the future if needed.

last_lemming OP
630 posts
 
@djohn
thanks for your thoughts.

The tubes are Sovtek 6550’s. So there should be no issue with those. 

As as for the tester I mention above, if I understand it right, it basically replaces the probe leads you would otherwise need to use. So the danger of sticking probes into unwanted places is greatly reduced. It would seem the only thing I need to “adjust” is the bias screw with a non metallic screwdriver. 

I emailed AR the tester probe and asked them if it would work for bias adjustment but I haven’t heard back from them yet. I also asked they send me any info for biasing the unit. 

As for the mod you did for the bias adjustment, according to what he remembered it was over the $1000 dollar mark.  An while it appears to be a great mod, I only paid $1500 for the whole unit.

The unit does sound amazing- no doubt about that - and I’m amazed at how quite it is. 
djohn
64 posts
 

Mod was not over $1,000 for the Bias Pots.

Please remember that I changed a number of Caps on the Circuit Board. There are other Caps that will need to be changed due to the Age of the Unit.

You seem to focused on Bias only at this stage.


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