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
Those terminal strips are a pain. You can buy adaptors on ebay to make it easier for you.
You can use small spades or something called "Pins". I owned this amp and don't remember using only bare wire. I'd try to find some budget speaker wire with small spades before I started chopping up my Bi-wire stuff. BTW, have those giant caps checked out (check for leaks, age etc.).
I live in an area devoid of any quality electronics repair. And before I send the unit off to AR, is there any simple visual things I can check or should be aware of? 

I bought the unit from Upscale Audio. I’ve purchased an AR PH3se from them and it’s been great. I know used equipped like this is a bit of the throw of the dice,  but they “say” it’s been bench tested and looked over and comes with a 90 day warranty, but I will call them to verify what was exactly done. 
You can these adapters if the spade terminals on the cable are too wide. I've used them on my McIntosh amplifier terminal strip.
https://www.ebay.com/p/1x-OEM-Copper-Banana-spade-fork-Plug-Adapter-for-McIntosh-Scott-Dynaco-Audio/...

My cables have banana plugs but I think you can use spades.

Upscale knows what they're doing so I wouldn't worry (in the short term). At some point, those caps need replacing (I had mine done at the local ARC dealer). Anyway, enjoy that wonderful amp!
last_lemming
... because it is Bi-amped I’ll then have two positives wires and two negatives  going to one channel ...
That's not biamplification, which would require two amplifiers.

I have owned the ARC Classic 60 since new.

Agree on the above comments in replacing the Caps. I would not send this to ARC since it will be very expensive. I just had mine rebuilt in the last few Month’s by Scott Frankland Associates who is very familiar with this Amplifier. The 4 Large Caps with Red Tops in the center of the Amp are called Filter Caps and Scott was able to source new ones that fit so these were changed.

There is also the problem of Tube Auto Bias on this Amplifier which does not work well. Every time you have to change the Tubes you need a Technician to Bias this Amplifier for you. If you do not have a Tech close by then it is a very large hassle with this Amplifier. Scott modded mine with test probe locations and adjustable pots so I can check my own Bias with a Meter since I was tired of lugging this Amp around for someone to Bias it. It was a brilliant solution.

If you wish to get by for now with your Cable connection problem order these;

https://www.partsconnexion.com/VAMPIRE-55446.html

They fit perfectly and they can be crimped or soldered. Two will also fit easily on each of the + or - Channel Screws. I do not recommend the Adapters mentioned above.

Do not use Bare Wire.

@djohn 
I was considering trying to change the caps myself.  I've done very little soldering in all actuality, but I am pretty hand and have good dexterity in small spaces.  To that end I've been watching all manner of youtube vids on the subject and I was going to go find some old broken gear and start practicing on it in hopes of trying to do this myself, but I might be kidding myself.

I will call to get a price on having this done for me.  

This is going in my secondary system so it's not a rush job for me.


last_lemming

You have a great amp there.

I’ve owned an ARC Classic 60 for 30 years and still keep it in reserve as a spare amp. I used it with an ARC SP-14. Then, I used it with my current ARC REF-3. It went into the "spare" designation when I got the REF-75se.

Over the years, I’ve used nothing but spade lugs on this amp. Larger lugs can be a pain, but smaller ones will fit, albeit with bloody knuckles at times.

If I were going to use the amp full time, I’d take it to a tech and have him remove the fins surrounding the speaker connections, and install Cardas pure copper binding posts and Cardas copper female RCA connections for the ICs. In addition, I would have the tech install a power cord input so I could use an aftermarket power cord. Have the tech measure the large caps. Replace if necessary. Not that expensive, really. You’ll be surprised at how good this amp is.

Frank
I called Mr Scott Frankland, nice fellow, and spoke with him about work that could be done on the Classic 60.  He indicated that the 4 caps aren’t soldered in, but screw in. So, in preparation of getting the amp I have purchased 4 Kemet capacitors that are a direct fit for the Classic 60.  But with a bit more overhead.

On Scott’s recommendation I purchased a variable voltage transformer to slowly bring the voltage up once the new caps are plugged in to make sure the electrolytics disperse evenly.  He highly suggested I do this, so I am.

my question is after the new caps are in and the amp has been brought up to power do I need to rebias the tubes, or is that only necessary if the tubes are replaced?
I'm sure it wouldn't hurt and you need to do it when you install new tubes (tube life is about two years with moderate use). Also, probably a good idea to check bias every six months just to make sure tubes are still working. I traded my Classic 60 in on a new VT-100 Mk-I in the mid 90s. I got a call from the dealer who told me one of the tubes was dead and had blown some kind of resister. I was totally unaware of the problem and offered to compensate him but he graciously declined.
Got the amp!  Damn thing is HEAVY. 

So I plugged it in and went to listen to each tweeter to see if there was audible hum - ear right up to it - NOTHING - ZERO NOISE!!  No hiss or hum at all. I thought hmmm , maybe it’s broke, nope it’s just that quite.  Music sounds wonderful. I can’t tell if the caps have been changed. What color are the stock caps color? Mine are blue.  

As far as being able to connect to the screw type speaker connectors on the back of the amp, I ended up cutting one of the legs off my speaker cables spade termination. This narrowed the spade width just enough to just fit between the fins of the amps speaker connectors   Snug too. Don’t worry about the speaker cables too much, there just old Blue Jeans cable, so no house mortgage was harmed. 
The Classic-60 got rave reviews when released (around 1990) as did the SP-14 preamp (its natural partner). I think I remember blue caps so they may be original (I doubt it). As I stated, Upscale Audio are pros so you should be good in the short run. Did they test your tubes? These pups can run into money especially if you buy them from ARC. Have fun!
The 8 power tubes are new. Thing sounds amazing for a 30 year old amp. Can’t imagine what a modern AR amp would sound like today. Can’t afford new, that’s for sure. 
So I see these bias testers.  Would these work to set the bias on the classic 60?

https://www.amazon.com/Nobsound-Current-Probes-Amplifier-Cathode/dp/B0777F8DBK
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.
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.

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.

@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. 

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.


I’m only focused in so far as making sure it initially runs without any hiccups and is set correctly, I will then focus on fixing other things down stream say in the next year or so.

After speaking with Scott, he was of the opinion that I shouldn’t rush to do anything just yet, but make sure it’s adjusted right and listen to it for a while. He says in many cases these units can sometimes check out in good health Ians don’t really need anything  done to them in the immediate time. 
If I wanted to discharge the current caps, is it simply done by leaving the music on, turning off the amp, and waiting for the music to fade out until there is zero sound? Then unplug the system. Or is there still residual voltage in the caps?
Sorry, that's above my pay-grade...
Hi last, I don't think AR is going to give you an opinion, especially in writing, on something that if they give you the right or wrong opinion and you get shocked to death that they have potential liability.  There are reasons you have been given warnings. 
No biggie. I found many videos and write ups explaining safe ways to do it. It’s not too complicated.