New Millett Hybrid Maxed Amp - Page 7

Woo hoo! Great job, Naamanf!

still waiting on boards...

Don't be sad, the group buy will come soon enough!

So, you lucky few who have a board...how is this thing working out for you? Any idea when the boards might be ready for a group buy? This may sound silly, but I really plan on matching a set of cans to this amp rather than the other way around...that's how excited I am about it! Sooo...any suggestions for phones for a basshead rocker that were just made to go with this amp, those of you who have been fortunate enough to hear it?

Okay this is more of just a general tube question but I have millet tubes now so I guess it's kinda related.

IIRC don't mix tube brands. However does the location of the getter flash matter, like can you use a side and a top together from the same brand ?

I think it does very well with the HD580 - plenty of voltage and slew rate to make those phones snap and pop, contrary to the complaints you often hear. 'Course, with the Senn's - it's always about the amp.

The Max is so detailed, it's also leading me to prefer the old PortaPro's over my beloved and ubiquitious KSC75's. I'm able to clearly hear the grainy midrange now in the KSC's. At the same time, the bloated bass blow in the PP's are very well controlled.

IMHO, and YMMV, of course.

IMHO, the order of preference in distinguishing tubes goes like this:
1. Type - 12AE6, 12AE6A, 12FK6, 12FM6 (preference among types is personal and gain-related, but that's the first distinguishing feature that should be considered)
2. Brand - GE, RCA, Sylvania, etc. (This one can get creative, because many of the smaller tube companies subcontracted these tube series to the biggies. Even some of the big ones subcontracted to the others for certain series - for instance, GE didn't list the FM6 in their catalogs. The markings appear to be RCA in origin. Nevertheless, A GE 12AE6A vs. a RCA 12AE6A vs. A Sylvania 12AE6A sound very different.)
3. Construction - as you note, the getter type and location is the distinguishing feature here, and it may vary within the same brand, depending on the vintage. The four types I've seen are:
1. Circular getters on top (halos)
2. Circular getters on the side (these are almost always the newest tubes)
3. Square getters on top
4. Square getters on the side.
There doesn't seem to be an advantage/disadvantage in sound among these getter differences, just that there may be a difference.

P.S. I'll be mentioning this in our web page documentation, but there appears to be a huge anectodal difference in bass according to the size of the cathode bypass cap. That cap for the regular Millett has historically been sized at 220uF, although usually a boutique is recommended. If you run the conventional wisdom equation for RC filtering of the cap, that 220uF is about twice the size as it should be. Nevertheless, I am recommending that a 1000uF cap should be used, or perhaps 470uF at the smallest. It appears to make a huge difference in the very lowest, slamming bass.

This reasoning is also reflected by Runeight's SOHA design, where he recommended as large a cap as practical in the cathode bypass positions, even though conventional-wisdom says the RC corner frequency needs nothing that large. However, the SOHA never lacked of any bass when following this strategy, and neither does the Max.

Since the output is the same, or almost, as PPAv2. Anyone tried to modify the output buffer to Dyn-O-Bias II? PPL had it post here

At this stage of the project we have limited the experimentation to just trying to verify the "base" configurations of the amp. It will be up to enterprising builders like yourself to tweak the amp further.

waiting for the group buy...

Just noticed the BOM was updated last week.
Time to tweak my mouser project.
I got a pack of 5 12AE6A tubes off ebay in the mail the other day.
I'm pretty excited to start putting this thing together!

got my boards today!!! they are beautiful... I cant wait to get this thing built. Where are we getting those cute green caps in CA7 L/R ???

Nichicon Muse ES ?

Yes. Handmade Electronics is an excellent source. The 1000uF, 16V is perfect in the cathode bypass (CA2L/R). A perfect output cap (CA7L/R) is the Nichicon Muse ES, 470uF, 35V. Unfortunately, that one is only at Michael Percy and at BDent. BDent happens to be a great source for the 2SC Toshiba and Sanyo output transistors, so that helps. For some reason, Handmade does not carry the 35V line of Muse ES. 50V versions of KZ's and Elna's tend to be 1-1/2" high. There is a high-quality 680uF, 35V Black Gate NX that would be an excellent choice for C7 - same for C2 - there's a 1000uF, 25V that's only 1" high. Of course, if you're using taller heat sinks, this isn't such an issue.

I'm jealous. Want to sell me a board?

Be patient, guys ... the Group Buy is coming ... very shortly.