[Russell Dawkins]

I second what Bob says, but would like to add that, even in professional equipment (and I'm thinking of an Apogee ADC I paid $4000 for in 1993), clipping indications are not necessarily trustworthy.

I had an occasion in around 1996 when I was getting obvious clipping distortion in my in-ear-monitors from a piano as I was recording it. I was flabbergasted as I was operating with my usual conservative margins (it's called "gain staging") for just this reason. All indications were that I had about 5 dB of headroom at each stage. The -5 dB O/L lights in the mic preamp were not flickering, the indications in the Apogee ADC were saying the same and the recorder (a Tascam DA 30), which actually had a resettable display storing the highest levels thus far in tenths of a dB was showing -2 dB, I think - that is, 2 dB of available headroom.

I didn't have time to experiment, so I never found out what the offending gain stage was, but I had to pull the mic preamp gain back about 5dB to completely eliminate the distortion.

I learned a couple of things from this

1/ how to recognize the sound of a gain stage just before obvious clipping (it sounds strained and reducing gain has a pleasant and relaxing clarifying effect).
2/ take all level indications (light, LEDs, meters) with a large grain of salt.

I have come across CD players where the analog output stage was apparently slightly clipping with 0dB (max level) signals of certain types. Piano is revealing because it is percussive and stresses the amplifying circuits yet tends to be smooth at the same time, so distortion is easy to hear. Vibes, for the same reason.

I have never seen so blatant an example of the disparity between indicated levels and apparently hidden or phantom levels (presumably brief transient dynamic spikes) than with piano though.

As to the Timepiece Minis question raised here, certainly turn it way down and listen close. If the distortion is still there, look upstream - it could even be the CD player's output stage! You could quickly check that by listening on headphones to the CDP if that's possible. If you have a variable analog out on your CDP, turn it down and listen again - maybe your preamp in is clipping.

Finally (and this is hard to imagine [!!]) it could be on the recording. I know a little distortion has occasionally got past me, although my client has always caught it and nothing I have done has gone "out there" with any clipping distortion that I am aware of.

[Aether Audio]

Russell,

Thanks for chiming in and adding a little validity to my earlier comments.  It's always good to hear from you!

I have little doubt that nothing gets past you in your recordings.  You must be in the top 0.1% of the engineers out there that strive for perfection.   My hat's off to ya for the piano observation as well.  I have found the same thing to be true in both my early days of recording and now on the playback end of things.  Piano is the toughest nut to crack and clearly shows the slightest bit of clipping.

Regarding recordings from other engineers though, you know as well as I do that in the high pressure/high business volume popular music world,that many engineers don't have the "luxury" of being as perfectionistic - even if they wanna be.  Even jazz and classical labels (which do tend to have the highest quality recordings) have deadlines to meet such that the engineers and producers often have to "fudge" it and let stuff go that would be better had they not. 

Then of course there's the guys that mix on jamboxes (yes... even big-name engineers in big studios).  Yeah, that's mostly rap and pop... but that still gives one an idea as to the extreme degree of quality control that exists in our modern recording world.  It's also a common fact that many studios select monitors based on what the studio down the street is using ("translation" of the mix to other systems is the argument).  Adding insult to injury, they often won't spend much on their monitors either.  After all "the shortcomings of the monitors aren't recorded on tape" since they're *ONLY* used for monitoring.

In the end its a small miracle that many recordings are as good as they are.  If it weren't for the high quality electronics that are available at very reasonable cost these days, that wouldn't likely be the case.  Now that you other guys all know, have fun finding all the mistakes!  

-Bob

[WGH]

The Minis are 87dB @ 1W/1M sensitivity each.  If you sit 3 meters away then one watt will produce an SPL of 75dB at your listening position.  To play at a relatively modest level of 85dB at the seating position you will then need 10 watts per channel.  Then suppose a 10dB peak comes along.  Now you need 100 watts to keep from clipping.  But... what if it's a 13dB peak?  Now you need 200 watts to keep from clipping.  The NuForces don't have that much output into 8-ohms and I'll bet they won't even reach their spec with a full 500mS burst.  Add to that, peaks as high as 20dB can occur on many of your better audiophile recordings.  Were you amp asked to reproduce one of those you'd need 1,000 watts!   

Looks like Frank will be selling more of his AVA Differential systems.

Of course one further advantage is that with a pair of Ultra 550 amplifiers, you have over a kilowatt of power available per channel.

[RodMCV]

Looks like Frank will be selling more of his AVA Differential systems.

Of course one further advantage is that with a pair of Ultra 550 amplifiers, you have over a kilowatt of power available per channel.

What is that  AVA Differential system and how do I learn more?

Is that 2 Ultra  mono stereo , 2 total or 4?

[konut]

Ok, I've had the Minis just over 48 hours and everything you guys have said about them is true. First, I'd like to thank Bob, his son Jason, and the other employees at SP Tech for allowing me to appreciate the craftmanship and quality of the junior member of the SP Tech line at the insane introductory price. I would never have been able to afford speakers of this quality otherwise.
Impressions:
These are among the most linear speakers I have ever heard. No point in the frequency response is emphisized or recessed.
At first, I just hooked them up in place of my previous speakers, working with the high pass filters and sub, and the system sounded great. The mid-bass on the Minis was much more well defined, the soundstage depth increased greatly, and the highs had the air that I've been missing. Complex orchestral passages became uncluttered. I could follow each section, strings, brass, woodwinds, etc, with ease, yet the whole sounded organic and cohesive. So THATS what the composer had intended! After a few hours of sampling various favorite cuts ranginging from rock, to reggae, to jazz, and bluegrass, I decided to hook them up "naked". Settle down now mcullinan, I wasn't naked, just no sub, running them full range. I was not prepared for the quality and quantity of bass these diminutive beauties produce. Kick drum astounded me with the tightness and depth of tone. Unbelievable! The only things I lost without the sub was the sense of space one gets with very good recordings of orchestras in great acoustically reverberant concert halls, synthesizer, and large organ pieces. More to come.  aa      

[WGH]

What is that  AVA Differential system and how do I learn more?

Is that 2 Ultra  mono stereo , 2 total or 4?

There is a thread in the Audio by Van Alstine Circle or better yet, call Frank. The AVA website has not been updated yet.

Wayne

[bhobba]

An "issue" with SP Tech speakers which a reviewer warned me about is that it's waaaaaaaay too easy to listen at a much higher volume than you might think.  Their super low distortion sort of hides (to me) the normal volume cues, so be careful. 
Purchasing a inexpensive (but relatively accurate) SPL meter may help preserve your hearing.

ABSOLUTELY.  Long term listening over 85db at your listening position is generally not recommended.  But you still need a MUSCLE amp to achieve those type of levels with an 87 DB speaker if you wish to avoid clipping.  My solution is to listen at 80db max, meaning I can get away with 100W easily - maybe even 50W.

Thanks
Bill

[lonewolfny42]

konut....

Ok, I've had the Minis just over 48 hours and everything you guys have said about them is true.

Hey....would we lie.....no.

Enjoy....they get even better with time.

(plus....you'll hear a difference compared to the Aperiodic 8's).

[Double Ugly]

I was not prepared for the quality and quantity of bass these diminutive beauties produce. Kick drum astounded me with the tightness and depth of tone. Unbelievable! The only things I lost without the sub was the sense of space one gets with very good recordings of orchestras in great acoustically reverberant concert halls, synthesizer, and large organ pieces. More to come.  aa      

Sounds like you may be ready for an Infra-Wave... or two. 

Seriously, if you think the Mini's bass is great (and it *is* great), you should hear Bob's proprietary T-line. 

[Double Ugly]

My solution is to listen at 80db max, meaning I can get away with 100W easily - maybe even 50W.

That's easy to say now, Bill, but I think you'll find that approach will be difficult to maintain.

If you like them as much as I hope, you'll want to play them a little louder... and a little more... maybe just a tad bit more... and before you know it, you're pushing 100dB.  I know, 'cause it's happened to me. 

They sound good at low volumes, too, but they really spring to life as you turn the volume knob clockwise.

[phoenix_rising]

They sound good at low volumes, too, but they really spring to life as you turn the volume knob clockwise.

I am in your camp double, I will crank mine till I find their limits. Why have a Ferrari if you aren't going to race it.

Phoenix