Volume Adjustment

Hello @teboerio 

This is an interesting discussion. Thanks for sharing. 

My rule of thumb for loudness is: 

+3 dB = doubles the acoustic power, but sounds only slightly louder.

+10 dB = sounds about twice as loud to most listeners.

+20 dB = sounds about 4× as loud.

+30 dB = sounds about 8× as loud.

Regarding the MA-252, I am not exactly sure why that is. I would ask the manufacturer for details. You can share my reference with them, and their engineers can get back to you about exactly how much louder they intended it be/sound  past 52.

Good luck with this.

@frank009, is a fraud! @frank009, is a FRAUD!

Mike

That’s strange 1 click would make that much difference. What about 51 to 52, is it a similar increase in volume? 

From your description it seems that there is something amiss with the volume control. There should not be such a big difference with a 1 decibel change!

something is wrong. measure with an spl meter to document the change, then give McIntosh the facts.

you can buy an inexpensive one (with a bottom hole for a tripod), it's good to have one

https://www.amazon.com/RISEPRO-Decibel-Meter-Digital-Sound/dp/B01EZZ8B5Q/ref=sr_1_15?sr=8-15

@teboerio  

The pot may have oxidized. DeOxit spray can be used, but be careful to keep it away from other components. Let it dry thoroughly before turning power on again.

If this doesn't work, it may be possible to disassemble the pot and clean inside it.

That is probably a job for your tech.

That sounds like an issue with the rheostat. I would talk to McIntosh. 

@kevemaher 

I would avoid using DeOxit for the time being if I were him.

If there is a hash-like sound or a crackling sound when you turn the volume up or down, it usually means the attenuator/knobs need to be cleaned, as they are making contact but struggling to do so consistently. In that case, DeOxit is the first thing you use.

@ditusa 

The gentleman asked for guidance, not for you to call me a fraud.

I will be respectful and ask you politely to grow up. 

Please grow up and behave like an adult. You are only embarrassing yourself.

@frank009, is a FRAUD! 

Mike

Maybe accurate 

The McIntosh MA252 utilizes a digitally-governed volume control that operates in precise 0.5 dB steps. The rotary volume encoder controls an internal precision resistor ladder, which ensures outstanding channel tracking and balance throughout its attenuation range. [1, 2]

For troubleshooting volume imbalances, you can make an even finer 0.5 dB step channel trim adjustment for left or right via the input trim settings. The bass and treble tone controls also utilize 1 dB steps for a maximum boost or cut of ± 10 dB. [1, 2]

If you are experiencing any channel imbalances, you can adjust the trim level or check if the source cables are seated properly:

I’m thinking your encoder is honker up

Also, imo EVERY audiophile should have test tones from a reputable source and an SPL meter…. And learn the basics of both..,

Thanks for the answers !  The volume control knob is smooth as silk and no crackling or popping. ( I have that issue on a MA-6500 I bought about 7 years ago and for which I just bought a can of Deoxit D5 but have not applied yet. Opening up the case was cake. Just a little hesitant on using the spray.)

And, yes, the Trim Controls work great and there are .5 db increases/decreases to Input Trim and 1.0 db increase/decrease for treble and bass which seem to be on target. 

SO . . duh . . the iPhone in my hand has a built spl app.  I will test 52 vs 53 volume setting and report back.  Problem will be I don’t have a sound source that is steady and a regular CD will have built in volume fluctuations.  Maybe I can find a volume test signal tone on Spotify. We shall see.  Over. 

Thanks for the answers !  The volume control knob is smooth as silk and no crackling or popping. ( I have that issue on a MA-6500 I bought about 7 years ago and for which I just bought a can of Deoxit D5 but have not applied yet. Opening up the case was cake. Just a little hesitant on using the spray.)

And, yes, the Trim Controls work great and there are .5 db increases/decreases to Input Trim and 1.0 db increase/decrease for treble and bass which seem to be on target. 

SO . . duh . . the iPhone in my hand has a built spl app.  I will test 52 vs 53 volume setting and report back.  Problem will be I don’t have a sound source that is steady and a regular CD will have built in volume fluctuations.  Maybe I can find a volume test signal tone on Spotify. We shall see.  Over. 

Okay . . . found CD Test track on Spotify (something like decibel.org from Amazon for free).

Used a 1,000 hertz test tone and it appeared that each Volume increase from 52 to 53 to 54 increased the volume by 3 dbs. 

So am guessing the MA-252, not being a high priced amplifier with a large volume knob like those on a Pass Labs amp, had compromised volume adjustment to about 3 db per volume control display. 

 Makes me recall what my Dad would say, “Poor people got poor ways.”

Uncle.  Over and out ! 

Ask Mac I seriously doubt the 3db step in right…. 

Also w test tones and a decent SPL meter you are ahead of many here….. 

The McIntosh MA252 does not use an old-style rheostat for volume control. Instead, its electronic attenuation system (reflected in the volume display) follows a logarithmic attenuation curve. As a result, the volume increase per step is not uniform; in some regions, each step may represent a larger change than in others.

It is quite possible that the 52–53 transition crosses one of these regions where the attenuation curve changes slope. My Cambridge Audio Azur 851A integrated amplifier has a similar type of volume control behavior, and I can also notice a slight jump at certain points on the dial.

On my system, the jump is noticeable but still within expectations. If you feel the step change is unusually large compared to normal behavior, it may be worth raising the question with McIntosh for confirmation.

I had an ARC preamp that had a blown shift register and it created what you are describing

I have an MA252 and have noticed no such phenomenon anywhere between volume settings of 30 and 85 (loudest I can set it before Amber lights indicate clipping levels). may be your device needs service. 

How are we supposed to know what an MA_52 is?  
This is a pet peeve of mine.  Why can’t people thoroughly describe their equipment instead of assuming we know what they are talking about.

What about 50 to 51? Or 54 to 55? Just curious.

Is there a calibration capability on the peace of equipment?

Deoxit-D5 is Generally usually used for "contacts" and switches.

Deoxit Fader F5 is Generally used for Rotating controls. Not for switches.

D-5 can flush the gel grease from you pots making them feel rough during rotation or in the case of Faders the same thing.

F5 is designed for Faderes and pots .But to much of either can flush out the control grease......Just My $.02 Worth.

not only an engineer but have designed and built many of these things.

Something is very wrong. Regardless of what the increments represent, they ought all be the same. If not its a weird (best thing I can say) design with crap (a technical term) human factors.

My designs were either 1 or 2 db each and consistent.  Its very small.

@frank009 Frank is a fraud, fraud is Frank (but only 009)

Check the Tubes, the gain could be off and the Volume control.