McIntosh amp help

[deepinton]

Just got some well used mc 501's and notice that the input selector switch doesn't do anything. I can connect XLR and nothing happens whether the switch is in balanced or unbalanced position. The amps output also doesn't appear to be anywhere close to 500w. Any ideas what could be going on? This is my first Mac so still climbing the learning curve

 

[lovinthehd]

Sounds like you need a new switch perhaps. If you're not able to analyze, sounds like you need to find someone who can analyze/repair it. How are you determining it doesn't have 500w output?

 

[deepinton]

So the expected function of that switch is to specifically cutoff the XLR input if it is set to unbalanced? Would a malfunctioning switch attenuate the input level? My power output suspicion is driven by ear - my old Classe CAV 180 (5x180 watts) sounds louder at the same pre-pro output level, all else in the chain being the same.

 

[lovinthehd]

So the expected function of that switch is to specifically cutoff the XLR input if it is set to unbalanced? Would a malfunctioning switch attenuate the input level? My power output suspicion is driven by ear - my old Classe CAV 180 (5x180 watts) sounds louder at the same pre-pro output level, all else in the chain being the same.

I didn't look into it, you're the one saying it doesn't do anything which sounds like it's defective....or you don't know what it's effect is. Unbalanced may have a lower output voltage. Does your old amp have same sensitivity spec to start?

 

[ski2xblack]

With used gear, your guess is as good as ours as to the condition. As hd mentioned, it could be the input selector switch. It might be something further downstream.

Double check all connections, just to rule that out.

Have you tried the unbalanced input?

Input sensitivity or overall gain may be less than the Classe. That may be an issue, although the Mac input sensitivity seems pretty standard (2.1v unbalanced, 4.2v balanced). What preamp are you using? If you're feeding the amp a balanced signal, are you using a balanced output from your pre-amp?

 

[deepinton]

Yes, the switch for sure doesn't do anything. I have 2 units and they both show the same symptoms. I am trying to understand what exactly it should do to help diagnose the root cause. Input sensitivity on the Classe is 1.35 v. Also, the Classe doesn't have a switch/selector for balanced/unbalanced. My pre-pro is a marantz 8802a. I have the 501 on a bench and working on getting the input board out so I can deoxit the switch and hope it helps.

 

[lovinthehd]

Yes, the switch for sure doesn't do anything. I have 2 units and they both show the same symptoms. I am trying to understand what exactly it should do to help diagnose the root cause. Input sensitivity on the Classe is 1.35 v. Also, the Classe doesn't have a switch/selector for balanced/unbalanced. My pre-pro is a marantz 8802a. I have the 501 on a bench and working on getting the input board out so I can deoxit the switch and hope it helps.

Maybe you need to dig into the manuals a bit. 2 units of what do you have? What are your particular connections/cables (not brand or claims, but what particular type)? What's the sensitivity rating of the McIntosh?

 

[lovinthehd]

Curious, why did you get the Mcintosh amp(s)?

 

[ski2xblack]

So, yeah, that confirms the Mac will need a hotter signal to get to the same volume as the Classe. (Marantz's pre-outs should be up to the task to give it what it needs, but you will need to advance the volume higher than with the Classe.)

I've got my fingers crossed for you that it's the switch, and not something else in the amp. Good luck with it.

 

[deepinton]

Curious, why did you get the Mcintosh amp(s)?

Just to see (hear) if it improves my listening experience. One gets used to a particular level of performance and then one wants more. You hear folks say 802d's do so much better with more power, so I had to find out. I also have the Buckeye Hypex amps, again, out of curiosity.

 

[lovinthehd]

Just to see (hear) if it improves my listening experience. One gets used to a particular level of performance and then one wants more. You hear folks say 802d's do so much better with more power, so I had to find out. I also have the Buckeye Hypex amps, again, out of curiosity.

So not a particularly reasonable move? B&W speakers are best improved by moving on....

 

[deepinton]

Maybe you need to dig into the manuals a bit. 2 units of what do you have? What are your particular connections/cables (not brand or claims, but what particular type)? What's the sensitivity rating of the McIntosh?

Looked through the manuals but didn't find any useful insights. I have 2 units of the MC 501. Connections are generic 15' XLR, generic 12 gauge speaker cable driving 802 D's

 

[deepinton]

So not a particularly reasonable move? B&W speakers are best improved by moving on....

Not sure if I have maxed out the capability of the 802s. They do sound great with the Hypex but I wanted more. That was one reason to get the 501's.

 

[ski2xblack]

You may hear a difference. That Mac is one of the autoformer coupled contraptions, so probably has different output impedance than the Classe or Buckeye, both of which have really, really low output impedance (as all amps should). I suspect the Buckeye and Mac would be the best to deal with the atrociously demanding load of the B&Ws.

 

[lovinthehd]

Not sure if I have maxed out the capability of the 802s. They do sound great with the Hypex but I wanted more. That was one reason to get the 501's.

How did you determine this "max" capability of the 802s?

 

[deepinton]

So, yeah, that confirms the Mac will need a hotter signal to get to the same volume as the Classe. (Marantz's pre-outs should be up to the task to give it what it needs, but you will need to advance the volume higher than with the Classe.)

I've got my fingers crossed for you that it's the switch, and not something else in the amp. Good luck with it.

You think something else in the amp could be causing the input selection issue, or something else in the amp could be causing my perceived "low power" issue? Any idea where else I should look besides the selector switch?

 

[deepinton]

How did you determine this "max" capability of the 802s?

Keep upgrading the rest of the chain till you can't squeeze out anything more? I refuse to invest in exotic cables and wires and found room treatments to be the best bang for the buck so far. Was really hoping these 501s would work out, but can't always win with 20 yr old stuff

 

[lovinthehd]

Keep upgrading the rest of the chain till you can't squeeze out anything more? I refuse to invest in exotic cables and wires and found room treatments to be the best bang for the buck so far. Was really hoping these 501s would work out, but can't always win with 20 yr old stuff

Well exotic cables would indeed be a useless effort generally....just more audiophoolya. Your expectations could be the issue more than anything else....

 

[deepinton]

Well exotic cables would indeed be a useless effort generally....just more audiophoolya. Your expectations could be the issue more than anything else....

Could very well be. Only one way to find out.

 

[lovinthehd]

Could very well be. Only one way to find out.

And that would be? Level matching and blind?