[willmueller]

Hi all


I've been a member for a while, been reading for a long time, and have some general DIY questions.

I've spent 80% of my wiring expierence in car audio and car electronics (ecus and such) and 19% in computer equipment all i've done thus far amp related is a couple cmoy amps so im a huge newb.

Im looking for something bigger and better.

I've got a decent pc and cd drive with an m-audio card and i need a better amp to power my headphones. (nothing special koss ktx pros)


I've looked around and watched others builds, and seen some prices (some have scared me) and i cant decide.


Just looking for a better alternative to a cmoy amp, and for under $300 and it has to be DIY as i need a new project.




Tube amps have caught my attention as i like how they sound... but i've found they border on over my budget.

What would you recommend and why?

oh and thanks in advance

heres a couple pics of what i've done thus far.... (again nothing special.... easy work)

http://i12.photobucket.com/albums/a2...n/P1270019.jpg
http://i12.photobucket.com/albums/a2...n/P1270020.jpg
http://i12.photobucket.com/albums/a2...n/P1270010.jpg

 

[heatmizer]

Solid State:
Pimeta
CKKK3
Tube Hybrid:
Soha
Millet Max

 

[willmueller]

hmmmmm the millet max seams like a much more involved project then the cmoy's i've built to date.


however i think im up for the challenge.


Heatmizer have you built either the soha or the millet max?

 

[heatmizer]

built the soha
The Max is a more complicated build but it is supposed to be a nicer amp than the soha.
I cannot compare the sound of each have not heard the Max.
"Tomb" might be able offer a more insighful opinion of the characteristics of each.

 

[doubtfulbroom]

solid stare

 

[jcx]

Quote:

Originally Posted by jcx /img/forum/go_quote.gif good guide to starting amp building: Audiologica also HeadWize Library - Projects is the usual place to find the public domain designs, lots of resources on Headwize, DIY forum, articles, technical papers head-fi's DIY forum can be searched for some info but the above are the motherlode

Headwize DIY forum also has a sticky thread on headphone amp projects

 

[ericj]

Quote:

Originally Posted by heatmizer /img/forum/go_quote.gif built the soha The Max is a more complicated build but it is supposed to be a nicer amp than the soha. I cannot compare the sound of each have not heard the Max. "Tomb" might be able offer a more insighful opinion of the characteristics of each.

i have both.

the millett max boards you can buy are certainly a more polished product than digi01's soha boards, but the amplifier circuit itself is fairly limited.

the millett max starts clipping at just 3 volts peak-to-peak on the output, so it's no good for high-Z headphones (such as most 600-ohm headphones, and basically anything referred to as 'hard to drive').

It also uses car radio tubes that aren't that great to begin with, and are not available in much variety.

the SOHA operates at almost 3 times the b+ voltage of the millett max, and thus more output swing before clipping is a given though i don't have the specs in front of me. It uses 12au7 tubes and it's close relatives - good preamp tubes - which come in many varieties and are very easily obtained.

Where the current SOHA falls down is on the output stage. The default configuration is a simple opamp, and this isn't anywhere near optimal. For some added complexity and money you can add jisbos buffers, which i hear are good, but i haven't heard them myself.

SOHA II is in the development stages and nearing prototyping, but i can't say when boards might become available. I can't share much in the way of detail but i can assure you all that the output isn't an opamp anymore. I will be building one of the first prototypes when the design is finalized, probably in a few weeks, after i finish building my Stacker II.

Might i suggest an excellent entry-level solid state amp: the Ck2III. You can build this for less than $150 including the enclosure work, and the performance is quite excellent for the effort required.

 

[nikongod]

Quote:

Originally Posted by ericj /img/forum/go_quote.gif the millett max starts clipping at just 3 volts peak-to-peak on the output, so it's no good for high-Z headphones (such as most 600-ohm headphones, and basically anything referred to as 'hard to drive').

For the fact that they are replaceable, I put 1.41v into my hd580. the word loud does not begin to describe. The amp "ran out of pot" at 8.5v with music.

I wont put 1v into my k240's or hd-414 (original 2kohm variant) because I like them too much, and they dont even need that much swing to get me going. Based on where others park the knob at meets, they dont need 1v either.

the millet excedes power requirements. the tubes may have a decent effect on where the amp clips though. i run sylvania 12fk6.

This is NOT a "high current biased" mosfet output based max, its an ORIGINAL head-fi board, with a diamond buffer daughterboard biased to idle at 25ma with bd138/139 transistors & no heat-sinks.

 

[TimmyMac]

Noone has mentioned Bijou yet? It's a pretty simple build... no SMD soldering or anything like that. I guess the high voltages could be scary but there's enough warnings and suggestions how to keep safe... it's also right at the top end of your budget.

 

[-=Germania=-]

I just ordered all the parts for my Millet Min and it might be a good place to start because it is all PTP and would give you something a bit more complicated than a CMoy, but not too much. Plus the cost is right! Mine is costing $55 in parts including the enclosure, tubes, parts, and power supply... that is everything!

 

[tomb]

Quote:

Originally Posted by ericj /img/forum/go_quote.gif <snip>the millett max starts clipping at just 3 volts peak-to-peak on the output, so it's no good for high-Z headphones (such as most 600-ohm headphones, and basically anything referred to as 'hard to drive').</snip>

Sorry, but this is just totally wrong - AMB's own measurements on Nate/Drew's revMH Millett Hybrid refute this:
Quote:

Originally Posted by AMB Maximum output voltage (prior to onset of clipping, 12AE6A tubes, 27VDC supply, 13.5V bias) 5.85Vrms (16.5Vp-p) into 330Ω 2.85Vrms (8.06Vp-p) into 33Ω

found at Ti Kan's Millett Hybrid Headphone Amplifier

A nice feature of the Millett and MAX design is that the output voltage increases with the higher impedance load. As you can see, you're about 13-1/2 Volts off in terms of the clipping behavior for peak-to-peak volts. Moreover, there's every reason to expect that trend to continue if one plugged in a 600 ohm load.

Primary testing on the MAX by both cetoole (the MAX's designer) and myself were with Sennheiser HD580's (300ohm). These were also referenced by Nikongod in his post. Until recently when Colin altered his MAX to serve as his desktop speaker amp, he used HD580's almost exclusively with the MAX.

Quote:

<snip>It also uses car radio tubes that aren't that great to begin with, and are not available in much variety.</snip>

Yes, the Millett Hybrid tubes are an easy target - too easy for some, it seems. They may not compete with a Golden Lion or a WE 300B, but pick another tube that's in its linear region in the 12-24V range, has similar heater voltages, and has usable headphone gains: it can't be done.

As for their variety, the Millett Hybrid/revMH Millett Hybrid/Millett Hybrid MAX tubes provide for three distinct gains, depending on load impedance, resulting in combinations from about 2 to 14 (paraphrasing AMB's tests again). That's not something you'll find in many tube amps or hybrids. Manufactured by at least four of the majors, they were packaged by just about every tube dealer on earth at one time or another. They are plentiful, cheap, and act in every way as genuine audio tubes - some good, some bad, and some great, IMHO.


P.S. I'm actually marveling at the response this thread has received since doubfulbroom resurrected it yesterday from July of last year with the single comment "solid star(t)e". The OP left this subject back on July 9 of last year.

 

[ericj]

Quote:

Originally Posted by tomb /img/forum/go_quote.gif Sorry, but this is just totally wrong - AMB's own measurements on Nate/Drew's revMH Millett Hybrid refute this:

I see pete has removed his comments about the original hybrid design from the starving student thread, too.

Quote:

Originally Posted by tomb /img/forum/go_quote.gif Yes, the Millett Hybrid tubes are an easy target - too easy for some, it seems. They may not compete with a Golden Lion or a WE 300B, but pick another tube that's in its linear region in the 12-24V range, has similar heater voltages, and has usable headphone gains: it can't be done.

I do wonder why the 12U7 has been ignored, but i'd rather just use a higher B+.

Quote:

Originally Posted by tomb /img/forum/go_quote.gif P.S. I'm actually marveling at the response this thread has received since doubfulbroom resurrected it yesterday from July of last year with the single comment "solid star(t)e". The OP left this subject back on July 9 of last year.

Yes, that is odd.