My_Ref Fremen Edition RC - Build thread

[badrisuper]

Originally Posted by bcmbob

Badri, Do you have anything to measure SPL - similar to this?

No, I dont have Bob. I try to get one if it is locally available. But what is the use of it?

[bcmbob]

That one is a little expensive if you don't use it a lot,and you might get a better deal on ebay or Amazon. I suggested it only because SPL (sound pressure level) is easier to interpret. There are standards expressed in db (decibels) the relate to real word situations. Loud, soft and such terms are all relative.

If you choose to, you can correlate your volume settings to a more scientific standard - also keyed to distance from the source of the sound. The efficiency and design of the speakers vary so much, it can be useful to know at what SPL in a given system the clipping occurs. There are also all the lab/hardware devices that can be even more informative - but that's still above my pay grade for now.

It obviously is not something that will influence the operation of the amp, and is completely optional - but is fun to have around.

[bcmbob]

Got my curiosity up so I went Googleing for "Software SPL Meter".
Found a couple possibilities:

REW - At least it looks impressive.

Audio Tool - Android app.

I downloaded both and will report in the morning.

[badrisuper]

Any suggestions for the clipping issues?

[dtses]

Originally Posted by ClaveFremen

Interesting... very similar impressions!

cool

Originally Posted by ClaveFremen

So, at the end a difference was there...

not huge, but noticeable! that is the main point.

Originally Posted by badrisuper

Yes it is loud enough to my room. But I wanted to try atleast 80% volume to see how loud it is!!!!

Mine 10k log Dale attenuator was set to 15th step out of 23 when I compared the caps. That was quite loud, not 80% of the scale, though more than a half. Do you use linear pot or log? It should be fine with the last one as we don't have linear hearing.

[badrisuper]

Originally Posted by dtses

Mine 10k log Dale attenuator was set to 15th step out of 23 when I compared the caps. That was quite loud, not 80% of the scale, though more than a half. Do you use linear pot or log? It should be fine with the last one as we don't have linear hearing.

Its a linear tracking pot.

[bcmbob]

The Audio Tool app is really quite remarkable. It was nice enough that I upgraded to the paid version ($6.95). More useful real time information than the dedicated RS unit I've been using. I don't own an iPhone or iPad but I'm sure there is an equivalent available.

Just a reference - with JRiver flac files using the program volume control - playing through a Mini2496 DAC - pushing the Sunflower speakers, there is no clipping at max settings. Just very very loud

[ClaveFremen]

Originally Posted by badrisuper

Its a linear tracking pot.

For volume control a log one should be used.

IMHO it explain why your volume goes up so quickly...

[AndrewT]

It is more likely that the system gain is too high.
A CDP putting out ~2.2Vac @ 0dBfs into an amplifier with 31.77times gain (+30dB) has the potential to give an output of 98Vpk if the amp supply rails were +-105Vdc.
Simply ludicrous to expect anything other than "just turned on" when using a normal potentiometer and bonkers to consider a linear law potentiometer.

read
What is Gain Structure?

[bcmbob]

REW (Room EQ Wizard) doesn't download completely in the Windows version. The OSX program is more sophisticated than Audio Tool but requires a mike input. I suspect it could be quite useful for FE builders - specially at the price - FREE.