Pass Labs X250.8 Meter Travel Question

[tino27]

Just curious ...

I know that for the first 18W or so, my 250.8 is biased in Class A. This means that under normal listening conditions, the meter barely moves (if at all) from its 11 o'clock position. And I know that once I cross that threshold, the amp will begin to draw additional current and the needle will begin to move to the right accordingly.

My question is ... what is travel distance between the Class A current draw at 11 o'clock and maximum current draw (when I am basically maxing out the amp)? In other words, what represents the maximum needle position? 1 o'clock? 2 o'clock? I'm not trying to max out the amp, but I would like to know how far the meter has to move before I need to start worrying.

Thanks!

(Edit: It has occurred to me that I may not fully understand how the meter works. If my assumptions are incorrect, I would totally appreciate an explanation.)

 

[BlueFox]

If you are 'maxing out the amp' your ears will tell you, and, yes, you 'need to start worrying'. I had the meters dancing on my amps before I ruined two speakers.

 

[tino27]

If you are 'maxing out the amp' your ears will tell you, and, yes, you 'need to start worrying'. I had the meters dancing on my amps before I ruined two speakers.

@BlueFox, perfect! As someone who has 'ruined two speakers' by having your 'meters dancing on my amps', then I would assume you'd be the perfect person to answer my question: How far is too far? Clearly I am looking to others to give me advice on what the limits are so that I don't 'need to start worrying'.

 

[Calvin]

The 250.8 is awesome! I own the Pass 260.8 monos. I've never had dancing meters as I never come out of Class A (to 34 watts on the 260.8s). On my present Pass XP-22 Pre, I never go above 70 dB - this is still Class A and is plenty loud enough with the 260s.

On the 250, I believe Class A is within the first 25 watts into 8 ohms (500 into 4 ohms). After 25 watts they go into Class A/B. This is when your meter will begin dancing. I don't think you will be able to tell using the meter that you are stressing out your speakers. Rather as already stated by BlueFox you will begin hearing some distortion thru your speakers ...

Some things to consider. How many watts are your speakers rated for? Are they 8 ohm speakers or 4 or? My Magico A3s are 4 ohm speakers so I have to double my amp power - i.e. my speakers are receiving 520 vs 260 watts per channel. But my speakers are only rated to 500 watts ... Pass amps are underrated on the power they put out. Your 250 likely put out more than 250 ... (how much more I don't know).

This said, your ears will let you hear any distortion. When you hear any, IMO you should back off a few dB. Memorize that setting and don't go above it. Ultimately this will sound better and help protect your system...

@BlueFox, perfect! As someone who has 'ruined two speakers' by having your 'meters dancing on my amps', then I would assume you'd be the perfect person to answer my question: How far is too far? Clearly I am looking to others to give me advice on what the limits are so that I don't 'need to start worrying'.

 

[tino27]

Thanks, @Calvin, for your reply. I feel like I should state a few things:

1. The speaker manufacturer recommends an amplifier that will put out about 200 W/ch into 8 ohms.

2. The speakers are nominally rated at 6 ohms, 3.9 ohms minimum.

3. The maximum rated power the speakers can handle are 400 W/ch (not specified whether that is into 4 or 8 ohms).

4. I DO know what it sounds like when an amp and/or speaker distorts (thanks to my college years). I am not trying to drive anything into distortion. This was a theoretical question only.

So, with that in mind: What the hell does the meter on the front of the 250.8 (or any other Pass amp) actually measure? Usually meters have a minimum and a maximum position that indicate the extreme ends of something.

 

[Jim Smith]

Thanks, @Calvin, for your reply. I feel like I should state a few things:

1. The speaker manufacturer recommends an amplifier that will put out about 200 W/ch into 8 ohms.

2. The speakers are nominally rated at 6 ohms, 3.9 ohms minimum.

3. The maximum rated power the speakers can handle are 400 W/ch (not specified whether that is into 4 or 8 ohms).

4. I DO know what it sounds like when an amp and/or speaker distorts (thanks to my college years). I am not trying to drive anything into distortion. This was a theoretical question only.

So, with that in mind: What the hell does the meter on the front of the 250.8 (or any other Pass amp) actually measure? Usually meters have a minimum and a maximum position that indicate the extreme ends of something.

I had a similar question with my Pass amp.

I called Pass Labs and spoke with Kent English. He was very helpful as he explained how my amp/meter worked.

 

[Jim Smith]

Thanks, @Calvin, for your reply. I feel like I should state a few things:

1. The speaker manufacturer recommends an amplifier that will put out about 200 W/ch into 8 ohms.

2. The speakers are nominally rated at 6 ohms, 3.9 ohms minimum.

3. The maximum rated power the speakers can handle are 400 W/ch (not specified whether that is into 4 or 8 ohms).

4. I DO know what it sounds like when an amp and/or speaker distorts (thanks to my college years). I am not trying to drive anything into distortion. This was a theoretical question only.

So, with that in mind: What the hell does the meter on the front of the 250.8 (or any other Pass amp) actually measure? Usually meters have a minimum and a maximum position that indicate the extreme ends of something.

I had a similar question with my Pass amp.

I called Pass Labs and spoke with Kent English. He was very helpful as he explained how my amp/meter worked.

I have since covered the meter, as I found it a bit distracting.