[bbm3]

Another set of eyes.

Should'nt C9L/R and C10L/R be QTY 2? (Mouser Version BOM)

 

[n_maher]

yup, just caught that one this morning while placing my Mouser order. Thanks for making sure though. I've PM'd Drew to fix the version on the web!

Nate

P.s. I guess I know better than to do parts spreadsheets at 11pm now

.

 

[bbm3]

I was going through the parts I ordered for the "original" Millett I was about to build prior to finding this thread and the group buy to see what I could salvage.

Do I understand correctly that I can still use the 100mfd 100v caps that I bought for the "original" with my 32ohm headphones?

BTW. Thanks for all the hard work Nate, Drew and everyone else. This is going to be a fun project.

 

[n_maher]

Yes, those caps will work fine. I've built some of my prototypes (as has Drew) based on the original parts list and you'll end up with a great sounding amp. We only modified the parts lists so that people would understand what other caps that they could use. The 100V caps are not required, but perfectly acceptable. I'll be building the Mouser version as soon as I can to compare and contrast and see if there's a difference to my ears. I'm no golden ear so I doubt I'll detect much if any difference.

Hope that helps.

Nate

 

[bbm3]

It sure does help. Thanks.
Now I have to stop beating myself up for buying the $40.00 board just a couple of days before I discovered the hybrid project.

 

[drewd]

Quote:

Originally Posted by n_maher yup, just caught that one this morning while placing my Mouser order. Thanks for making sure though. I've PM'd Drew to fix the version on the web!

It's fixed!

Quote:

P.s. I guess I know better than to do parts spreadsheets at 11pm now .

No way! You've got to live dangerously!

 

[bbm3]

Has anyone tried installing LEDs at the bias test points to allow adjusting the L/R bias by eye? Or as a visual indicator if the bias has drifted?
Are the tubes stable enough that once the bias is set with a meter at normal operating temperature you can forget about it?

 

[AtomBoy]

Quote:

adjusting the L/R bias by eye?

I've been looking for inexpensive voltmeters to wire to the bias points, but I'm not sure what that would do to the audio. I'd be interested if someone has any ideas here.

 

[drewd]

Quote:

Originally Posted by bbm3 Has anyone tried installing LEDs at the bias test points to allow adjusting the L/R bias by eye? Or as a visual indicator if the bias has drifted? Are the tubes stable enough that once the bias is set with a meter at normal operating temperature you can forget about it?

The bias has not drifted on mine after about a month. Also, at least to my ear, the bias setting is not absolutely critical - with a set of 12FK6's, I can't hear much of a difference within a couple of volts of 12V bias.

Quote:

Originally Posted by AtomBoy I've been looking for inexpensive voltmeters to wire to the bias points, but I'm not sure what that would do to the audio. I'd be interested if someone has any ideas here.

Very little, if any. The circuit will see a voltmeter as a very large resistance to ground. Any noise that the voltmeter introduces will be insignificant in terms of the distortion in the amplifier itself. Remember, this is not a solid state device that will have virtually no distortion - count on around .5% to 1% distortion. The power supply will generate more noise than you'll hear from the voltmeter.

Consider, though, that a voltmeter will really be an aesthetic fixture on the amplifier - the tubes have an extraordinarily long life, so the bias should not drift. Of course, there's nothing wrong with a nice looking amp and there are plenty of classy meters out there! I would recommend finding a meter that has the bias point as close to mid-range on the meter as possible, since that is the most accurate area on an analog meter.

-Drew

 

[bbm3]

Quote:

Originally Posted by drewd The bias has not drifted on mine after about a month. Also, at least to my ear, the bias setting is not absolutely critical - with a set of 12FK6's, I can't hear much of a difference within a couple of volts of 12V bia

Thanks for the input Drew.
I think I'll pop a couple of LEDs in the bias test pads just for grins as long as it isn’t going to adversely affect the circuit.

AtomBoy,
I was thinking cheap, as in LED, but a couple of analog meters would be way cool.

In the next few weeks we should begin seeing some very interesting variants of the hybrid.

 

[n_maher]

Quote:

Originally Posted by bbm3 In the next few weeks we should begin seeing some very interesting variants of the hybrid.

This is something I'm very much looking forward to

. That and hopefully heraing lots of people who having a great time building themselves an amp. I've got a couple of special Milletts lined up, just not sure when I'll get the time to build them. I guess there's always the winter to look forward to.

N

 

[dsavitsk]

A note about the project website:

Drew suggests that a Velleman PS is a good choice. At the voltages used in the Millett, some of the parts in the Velleman are slightly underspeced, particularly if you use a transformer that has a secondaries at around 30V. For instance, there are 2 electrolytics that are 35V, and there is a trim pot and a resistor that are likely at too low of a wattage rating. Replacing these four parts is probably not essential, but doing so is relatively inexpensive and adds some safety margin.

Here are some threads:
http://www6.head-fi.org/forums/showthread.php?t=109928
http://www6.head-fi.org/forums/showthread.php?t=114261

 

[JWFokker]

Quote:

Originally Posted by bbm3 Thanks for the input Drew. I think I'll pop a couple of LEDs in the bias test pads just for grins as long as it isn’t going to adversely affect the circuit. AtomBoy, I was thinking cheap, as in LED, but a couple of analog meters would be way cool. In the next few weeks we should begin seeing some very interesting variants of the hybrid.

If anyone does analog meters, I want to know about it. I love 'em, but I have very minimal knowledge when it comes to electronics design so I'd have no idea how to implement them.

 

[ble0t]

Here's a couple links as long as they got brought up...

http://www.mpja.com/productview.asp?product=8718+ME

http://www.surplussales.com/Meters/MtrDCVoltsmain.html

There's nothing too complicated about wiring them up...you just need to connect it across the load you want to keep track of.

 

[skyskraper]

there were a couple of threads on vu meters (both led and needle types) that had some cool links n stuff to pre circuits to drive them and info on using the good ones and not so good ones etc.

not for a millet tho

dynahi mebbe.