[Stikk]

Hey Everyone..

Ok so I am 99.99% sure this has been covered here somewhere before, but I don't know where.. In my exam procrastination I came across this and.. Well.. I'm in love. I want it, badly! Hopefully, this summer, I will have a job that is paying me the cash I need to buy one of these little miracles and believe me, as soon as I can afford it, I will be buying one..

But in the meantime, I thought I would float an idea around.. A simplified DIY version, based on the same idea of a portable battery-powered tube amp in the form of a modified version of the infamous millett hybrid design..

I have done a little research and have found very little about this kind of thing, I have managed to find out that these subminature tubes used to be used in everything from hearing aides to portable guitar amplifiers but I couldn't find a successful DIY tube amp that runs off batteries and is portable..

The TTVJ version of this amp claims up to 40hrs of playing time on a charge and I would be more than happy with a quarter of that. I am rarely away from a power point for more than 10hrs at a time and if I am, I can use a SS amp if I get desperate!

So I suppose my question is this: Has anyone (other than TTVJ) successfully implemented this design? If so, is there a schematic I can have a look at as a starting point or am I gonna have to try and design this thing from the beginning? At the moment, the only millett design I have actually looked at and understood is the Starving Student version.. Would anyone more experienced be willing to help me out in designing this amp??

 

[tomb]

TTVJ didn't implement the design - Pete Millett did. TTVJ sells the portable Millett Hybrid just as they do his ultra-high-end Millett.

More to the point, though -
Since Pete is such a wonderful benefactor to the DIY community for so many of his other designs, it would be in poor taste to try to replicate a DIY version of a product he's actively selling.

Just MHO ...

 

[cobaltmute]

You may find this thread useful. I hadn't read all of it but it did talk about portable tube amps

HeadWize: DIY Workshop > Teeny, tiny, tube hybrid - Interest & Reality Check

 

[Stikk]

Quote:

Originally Posted by tomb /img/forum/go_quote.gif TTVJ didn't implement the design - Pete Millett did. TTVJ sells the portable Millett Hybrid just as they do his ultra-high-end Millett. More to the point, though - Since Pete is such a wonderful benefactor to the DIY community for so many of his other designs, it would be in poor taste to try to replicate a DIY version of a product he's actively selling. Just MHO ...

Hi tomb,
Oh, right, I realized Pete Millett was at least involved in the design but since TTVJ said in the description "our first amp!", I simply assumed it was their take on his design..

I didn't mean any disrespect to Pete, obviously, not trying to cut his grass here or anything, I was kinda suggesting a simpler design than the one he's selling commercially, rather than one that competes directly.

Thanks for the link, cobaltmute, I'll have a read through that and see what's what but I think for now, I won't push this one too hard, I don't want upset anyone (especially Pete!) so maybe I'm better off just workin my butt off and buying one from TTVJ!

 

[-=Germania=-]

Have you looked into the YAHA (s)?

 

[Stikk]

Quote:

Originally Posted by -=Germania=- /img/forum/go_quote.gif Have you looked into the YAHA (s)?

I have, yeah, they all seem to be pretty miniature but they all seem to need a wall supply, and I was hoping for batteries.. There are a couple of battery powered ones but the battery packs are huuuuuge.. I think my working plan is to save up for a TTVJ one but I will have a closer look at the YAHAs, see if I can get one to run on a Li-ion or something? We'll see..

Hey Germania, while you're here, just wanted to tell you I LOVE your SS Hybrid, have seen pics of it here everywhere and it really is a work of art.. How much did it cost you to build, just out of interest? Did it put it out of the "starving" category?

I have like a million questions about it, I would love to build one like it at some point but I'm gonna build a standard SS Hybrid first, just to make sure I like it..

 

[PhaedrusX]

take a look at Sijosae's gallery:

http://www.headphoneamp.co.kr/ftp/sijosae/Gallery/

he's managed to completely enclose a tube hybrid design in an altoids-like tin, complete with a 9V battery.

 

[Stikk]

Quote:

Originally Posted by PhaedrusX /img/forum/go_quote.gif take a look at Sijosae's gallery: http://www.headphoneamp.co.kr/ftp/sijosae/Gallery/ he's managed to completely enclose a tube hybrid design in an altoids-like tin, complete with a 9V battery.

Oh my god, that is VERY impressive.. I wonder how it sounds.. It looks amazing, I can't believe he managed to do that.. I wonder if I could do something similar.. Albeit in a slightly bigger enclosure, my soldering skills surely do not rival his..

 

[-=Germania=-]

You gotta tell me which build you are referring to.

I have built 4 of those amps.
The two that you have probably seen lately are the Nascar 24 I did for Headphone Addict and then the 3 channel build that I currently use.

EDIT:
The Three Channel one:
Partial RDS Kit ~$60
Cases ~$17
Lighted Power Switches ~$16
Output Caps and Extra Power Caps ~$0 a donated item from an audio god
Separate PS module ~$32
PS Part changes ~$8
Lots of Extra Tubes ~$48 (I had to find 3 matched tubes)
Additional Parts (Power plugs and recepticals) ~$14
Wire ~$15 (I already had this around)
Silver Solder ~$6

Total Cost: ~$216
That is including shipping.

The Output Caps are Bypassed with Wima MKP10, the PS is actually a Medical PS module that has universal input (so anyone around the word can plug it in without any modifications) with some better Caps/resistors put in at certain points, the Power supply is further coupled to even out the bass response.
If you had some of these parts on hand, a set of matched tubes, and some cheaper parts selections (Switches and recepticals) it could be done for about $150 with the cases. The cap upgrades on the PS were just to improve reliability and brought the noise floor to inaudible. If you do the standard BOM, make sure and get another 470uf 63V Power Cap to put across the DC input because the Cisco PS varies and some create some not so nice noise floors without it.

The Build I did for Headphone Addict was using the 2-channel RDS Kit, had Wima's Bypassing the output caps (which were Nicho Muse in this case), used the same high Grade SPC as I did in my amp, and used Jameco Tin/Silver/Copper lead-free solder because it would be used around kids.

I just found a post with some sound info on the Nascar 24
I will let the people of Chiunify post about the 3 channel SSMH that will be there.

 

[myinitialsaredac]

Sijosae's amp is amazing oO. I wonder what the price in parts was for that and how long it took to build. Someone *cough cough* should replicate his builds for us head-fiers who are unable to handle soldering irons with any kind of results.

Dave

 

[-=Germania=-]

Why not ask Sijosae?

 

[myinitialsaredac]

Would seem like a good idea wouldnt it?
Hmm, I may have to do that one day oO.

Dave

 

[Stikk]

Thanks for that info, Germania, that was indeed the amp I was referring to. I would love to build one. Just out of interest, though, what is the advantage of the active ground? Is the design of the amp pretty much the same but with an extra channel to amplify the ground? I'm reading through the SS thread, slowly, I wanna read it all before I build one so I assume you've discussed it there so I'll get to it eventually

Another thing I was wondering, where are your MOSFETs on that amp? Are they inside the case? If so, don't they overheat..?

Ok, anyway, back to the original topic, I looked at Sijosae's schematic and PCB layout, I think it would be possible to replicate without too much difficulty, maybe I will give it a shot after exams