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New Millett Hybrid Maxed Amp - Page 433

post #6481 of 6589
Quote:
Originally Posted by ModMax View Post

Quote:
Originally Posted by KimLaroux View Post

My cheap DMM shows 0.6 Ohms when I touch the leads together. Was this 0.2 Ohms measurement error-corrected? If not, then those 0.2 Ohms were probably just the impedance of the leads and the points of contact.

 

From what I can understand, your enclosure is grounded at two places. This sounds like a ground loop, and could explain the hum you get.

 

My DMM shows 0.1 Ohm with just the leads contacting one another.


Do you have a source with RCAs?

Connect it and see if there is hum.

You really don't need to play anything, just connect the cables, you can turn it on, too. Don't play anything. Basically, if it's really close to silent (I have a hunch it will be) under actual playing conditions, what does it matter if there's some RFI/noise when conditions are such (ie: nothing connected) that you cannot play anything?

post #6482 of 6589

Is it recommended to set the volume of a source (iPod, laptop, etc..) to its maximum when connecting to an amp or dac/amp like the MOSFET-MAX?  I noticed that when I connect my grubDAC to my laptop, the laptop automatically sets its volume to max.

post #6483 of 6589
Quote:
Originally Posted by ModMax View Post

Is it recommended to set the volume of a source (iPod, laptop, etc..) to its maximum when connecting to an amp or dac/amp like the MOSFET-MAX?  I noticed that when I connect my grubDAC to my laptop, the laptop automatically sets its volume to max.

If you're using a digital line-out source (sound card or DAC on a PC), absolutely set the volume to maximum.  Otherwise, you get software interpolation in the signal which can degrade the quality.

 

iPods are different, unless you have a line-out adapter.  The signal from an iPod headphone output is already amplified analog.  It's among the worst of sources that you can connect directly to an amp.  If you're using the iPod headphone jack, then adjust things so that they're stable and you're not driving the MOSFET-MAX into clipping.

 

All other analog line-out sources have no volume adjustment, anyway - they follow IES/Phillips/Sony Redbook standards (hopefully, anyway).

post #6484 of 6589
Quote:
Originally Posted by tomb View Post

If you're using a digital line-out source (sound card or DAC on a PC), absolutely set the volume to maximum.  Otherwise, you get software interpolation in the signal which can degrade the quality.

 

iPods are different, unless you have a line-out adapter.  The signal from an iPod headphone output is already amplified analog.  It's among the worst of sources that you can connect directly to an amp.  If you're using the iPod headphone jack, then adjust things so that they're stable and you're not driving the MOSFET-MAX into clipping.

 

All other analog line-out sources have no volume adjustment, anyway - they follow IES/Phillips/Sony Redbook standards (hopefully, anyway).

 

So iPod dock to LOD adapter to MOSFET-MAX RCA = set iPod to max volume, correct?

 

What about PC headphone out to MOSFET-MAX RCA?  What would you recommend in this case?

post #6485 of 6589
Quote:
Originally Posted by ModMax View Post

 

So iPod dock to LOD adapter to MOSFET-MAX RCA = set iPod to max volume, correct?

 

What about PC headphone out to MOSFET-MAX RCA?  What would you recommend in this case?

A PC headphone out is worse than an iPod headphone out, IMHO.  If you don't have a sound card with line out, then that's why you have the grubDAC - connect to the USB and forget about it.

 

I don't have your equipment, though, and know nothing about the details of your setup.  Why don't you try it?  If it sounds like crap, then don't use it that way.wink.gif


Edited by tomb - 11/21/12 at 3:13pm
post #6486 of 6589

An ipod with LOD, you cannot control the volume, it defaults to 1V rail-to-rail.

post #6487 of 6589

Can anyone recommend a good source for a volume knob for the ALPS pot on the MOSFET-MAX?  I like the Kilo knobs, but all of their shaft lengths are only .510" which is too short for the ALPS pot shaft.

post #6488 of 6589
Quote:
Originally Posted by ModMax View Post

Can anyone recommend a good source for a volume knob for the ALPS pot on the MOSFET-MAX?  I like the Kilo knobs, but all of their shaft lengths are only .510" which is too short for the ALPS pot shaft.


Tomb suggests an ebay seller, where I got mine from. I actually still have one I may never use. His site is here: http://myworld.ebay.com/hongkongsuperseller/

 

Radio Shack has some okay knobs, too.

 

With that ebay seller, I did have to cut the shaft slightly, FYI.

post #6489 of 6589

What tool did you use to cut the shaft?

post #6490 of 6589
Quote:
Originally Posted by ModMax View Post

What tool did you use to cut the shaft?


A saw. A very small hand saw.

post #6491 of 6589

I use a Dremel cut-off disk (or however many it takes - they break often):

 

It slices through like butter until you get about 3/4 of the way through the shaft.  By that time, the cut-off disk has loaded up a bit on the metal and may start to kick out of the cutting groove.  Stay with it and be patient and you'll have a fantastic cut in about 10 seconds.  One of those grinding stones that typically comes in a Dremel kit has a huge counter-sink that lets you finish up the pot shaft end nicely:

 

It's a typical bit that looks like the above.  It actually has significant depression in the top (counter sink).  It's almost like a hole that's the same diameter as the pot shaft.  Use this bit by inserting the end of the pot shaft into the top depression of the Dremel bit (you should actually move the Dremel, not the pot shaft), and it smooths and rounds off the freshly cut shaft very nicely.

 

A saw is OK, but at the risk of disagreeing a bit with scootsit, it may tend to put a bit more stress on the pot shaft.

post #6492 of 6589

Has anyone had any luck with Kilo knobs on their Millett MAX builds with ALPS RK27 pot?

 

The shaft length on the Kilo knobs is 0.510 inches, which would mean a pretty good trim (a little more than .25 inches) needed for the ALPS pot shaft to shorten it so the knob base sits close to flush against the case front panel.

 

Specifically, I am considering this knob with a 6mm diameter shaft?

 

Digikey Product Page:

http://www.digikey.com/product-detail/en/ML-90-3-6MM/226-3028-ND/305260

 

Kilo Datasheet:

http://media.digikey.com/pdf/Data%20Sheets/Kilo%20International%20PDFs/ML%20Knobs.pdf

 

Should I go for a .25 inch diameter shaft or will a 6 mm diameter shaft work fine? 

 

Also, given the set screw is .285 inches from base of knob, and with the ALPS pot shaft trimmed to a lenght of approximately .510 inches, would the position of the set screw be an issue for securing the knob to the ALPS pot shaft securely, in your opinion(s)?

post #6493 of 6589
Quote:
Originally Posted by ModMax View Post

Has anyone had any luck with Kilo knobs on their Millett MAX builds with ALPS RK27 pot?

 

The shaft length on the Kilo knobs is 0.510 inches, which would mean a pretty good trim (a little more than .25 inches) needed for the ALPS pot shaft to shorten it so the knob base sits close to flush against the case front panel.

 

Specifically, I am considering this knob with a 6mm diameter shaft?

 

Digikey Product Page:

http://www.digikey.com/product-detail/en/ML-90-3-6MM/226-3028-ND/305260

 

Kilo Datasheet:

http://media.digikey.com/pdf/Data%20Sheets/Kilo%20International%20PDFs/ML%20Knobs.pdf

 

Should I go for a .25 inch diameter shaft or will a 6 mm diameter shaft work fine? 

 

Also, given the set screw is .285 inches from base of knob, and with the ALPS pot shaft trimmed to a lenght of approximately .510 inches, would the position of the set screw be an issue for securing the knob to the ALPS pot shaft securely, in your opinion(s)?

All the knobs I use I get from PartsPipe on ebay - also know as HongKongSuperSeller.

 

This is a PartsPipe knob,

and this:

 

Strictly speaking, the ALPS RK27 uses a 6mm shaft.  An English knob will have a wobble.

 

Finally - JMHO, but never, ever cut the pot shaft based on calculated dimensions.  Assemble your amp, try the knob on for fit.  See how much space you have between the back of the knob and the front surface of the front plate.  Cut this much off of the pot shaft - no more.  You should still have enough play beyond the set-screw to provide some clearance so that the knob doesn't rub.

 

I put my amps in a large freezer bag (or a kitchen garbage bag) with a small hole cut through the bottom for the shaft.  I put some masking tape around the base of the shaft where it pokes through the plastic bag for added safety.  Then I pull out the Moto-Tool and cut.  The bag protects everything from the aluminum dust.  Also, not only is your pot locked into the PCB, but the shaft nut provides additional stability and protection from torquing/bending the shaft when cutting.  There's no danger of that with a Dremel, but you could scar up other things without the baggie. 

post #6494 of 6589

(edit: looks like tomb beat me to the punch)

 

The ALPS pot has a 6mm shaft.

 

The way I trim a pot shaft to length is:

 

1) Install the pot onto the front panel.

 

2) Place the knob on the shaft.

 

3) Measure the distance from the backside of the knob to the surface of the front panel in mm.

 

4) Remove the knob and the pot from the panel.

 

5) Measure from the end of the pot shaft to match the distance you measured in step 3 and mark a line on the shaft.

 

6) Cut the pot shaft just slightly in front (toward the shaft end) of that line. Be sure the cut is flat, and not at an angle.

 

7) Reinstall the pot to the front panel. Install the knob. If the knob is too far away from the panel, file the shaft down

    until the knob sits where you want it too. Then file the cut edge smooth.


Edited by funch - 11/29/12 at 3:09pm
post #6495 of 6589

Talking about RK27 and knobs... The RK27 I got has a perfectly round shaft, like so:

 

AlpsBlueRK27-1-800x600.jpg

Yeah that's a totally random picture ;)

 

Are these shafts meant to be used only with knobs that have screws? Or is it possible to mount a screw-less knob to this type of shaft?

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