So.......... I received my Millenia MG3 amp from Jan today.
First thing I did was hook up my vintage Yamaha HP-1 headphones... Initial impression with female vocals (SHEL) VERY positive. The HP-1 in stock form tend to be dark, or at least lean toward the dark side (Luke... Oh, never mind). These are my go-to headphone despite the fact that they are not the BEST headphone I own. The HiFiMan HE-6 hold that honor.
I listened to a couple of tracks and found myself continually dialing down the volume. Too loud! Turn it down! So, what does it sound like against a couple of other amps on the shelf?
I went about the task of measuring and setting a set SPL level between the Millenia and an old-school Parasound HCA-1000A amplifier (John Curl design, you know!).
Pink noise has been my go-to for setting SPL level between amps, headphones, and such... Right off I discovered a dramatic difference in the perceived "loudness" with identical SPL levels between the MG3 and the Parasound (C weighted). If I set the Parasound output to a decent listening level, swap to the MG3 and set identical SPL, the same track is much too loud! Repeat, repeat repeat... yeah, same result....
OK, time to break out the Scientist in me. Launch REW (RoomEquilizer) and take some measurements. Sure enough, no matter what I do to ensure the set up is as close to identical as possible between the Millenia and the Parasound, from 2 kHz and above the Millenia measures between 3 and >10 dB higher than the Parasound.
I think to myself, Self, maybe the problem is with them old Yammis! Try those fancy HE-6's! To my dismay, dern near same result. Much enhanced 2k+ frequency range on the Millenia over the Parasound. OK, maybe the Parasound is the problem! Squelching the high frequencies! Lets compare to the First Watt F1! OK... Same problem. Frequency response measurements of the Parasound HCA-1000A and the First Watt F1 with the HE-6's very nearly overlap (within experimental error).
Being bothered by the inequity of perceived loudness and SPL measurements, I investigated other noise forms. Violet, blue, blah, blah, blah.... gray... there it is... Gray Noise. If I set SPL equivalent between MG3 and other amps, PERCEIVED loudness is much closer to "the same".... Boy is this an inexact science! Gray noise seems to help, though.
Need to go back and do some A/B listening with the Gray Noise technique.
Next, I went to some favorite test tracks that especially emphasize bass response: The Dead Weather: 60 Feet Tall and Hang You From The Heavens. Holy CRAP! What is that I hear!?!?!? Bass clipping!?!?!? Quick comparo to F1... Yup... F1 sounds like it should... Bass clipping in the MG3.... Need sleep and further investigation...
Back to SHEL, HP-1, MG3.... Heaven... (SHEL is amazing, by the way, if you are not familiar with them).
Config notes: Signal path is flac played via Foobar2k->Schiit Gungnir->MG3 on 24 VDC wall plug (no battery or capacitor bank operation yet, sorry)
flac played via Foobar2k->Schiit Gungnir-> First Watt B1 preamp -> Parasound HCA-1000A or First Watt F1.
SPL measurement duties: Radio Shack SPL meter.
Bass clipping observations through my resistor box driving HE-6's. Bass clipping not observed with Yamaha HP-1's and resistor box.
I plan to run the HE-6's direct to the MG3 to see if the resistor box is forcing the drive level too high, causing the clipping behavior.
MG3 Hiss... Its there, but pretty minimal with both the HE-6 and HP-1's. Apparent enough that the resistor box was definitely helpful. It may be that tuning the resistor values will allow the elimination of hiss and not induce clipping. Time and experimentation will tell.
Edit to add I've noticed clipping on The Dead Weather, 3 Birds with the MG3... Gotta look at the resistor box and see what I need to do to reduce the resistor divider. Bass extension is not nearly as good on this track with the MG3 as it is with the B1/F1 combo... Expecting too much? Gary set my expectations very high... I blame it on him! (j/k Gary :) )
Edited by potterma - 8/31/13 at 6:16am