Millett "Starving Student" hybrid amp - Page 71

Ok read most of it. So this will work for what I Am trying to do?
Trying to put Rcas and Headphone jacks.
103-7002-EVX

I think a "on none on" or "on on" type of DPDT switch may be a better option.
That way there is no middle off position.

I would also suggest silver plated contacts and something that will not take a bunch of force to activate (with an external power supply
this is a pretty lightweight amp and you don't want to have to hold on to it to keep from sliding half way across your desk while you flip the switch )

611-7101-064 ??

Oh Ok that makes a lot more sense. Yea imagine me just finishing my build and switching sources and pushing it all the way across my desk because of a switch. Thanks MisterX

Is it to be expected that some tubes might glow at different intensities than others? I've got a few different tubes, and it looks like one doesn't glow as bright.. not an issue with the wiring, as it follows the tube.

I believe I have conclusively demonstrated that some noobs^h^h^h er, tubes do not glow as brightly as others.

Any chance this can be made to work with a 24v Sigma 11 PSU laying around, and if so what changes would need to be made? Thanks from a DIY noob!

First, it's a big mis-application. Second, the 48V from the VoIP is already reduced voltage for the tubes (by one-half, at least), so 24V would be even worse. A 24V Sigma 11 would be more suitable for pairing with a Millett Hybrid, not the SSMH.

Thanks, I got it to pair with my Travagans Red headphone/speaker amp for driving my Stax energizer. Just trying to find out what else it can be used with.

a little help

hi all, i have a couple of question that hope one of you could answer. currently still reading this thread (100+ pages, it takes a while) so sorry if some have been answered before. i am sourcing from the UK, due to the fact that i live there , from a shop called maplin, as it is the easiest for me. but, as you can appreciate, there are some problems. Also, sorry if these seem a bit stupid to you, just humour me and answer them anyway.

Firstly, for the 150uF63V electrolytic capacitors, do i need axial or radial? Also, i read that for low impudence headphones (40 ohm ATH-W1000 for me) a slightly higher uF should be used. but what is slightly higher? 220, or 470 or 1000uF? also, should i use 63 or 100V? I presume 63 would be the best.

Next, for the film capacitors, are mylar ones ok? they are only ones i could find. also, i dont know if these should be changed to suite any changes above, if so, which ones are best, 0.1, 0.15, or 0.22uF?

For the Phono (RCA) jacks, do they have to be insulated? The only insulated ones i found are teflon insulated, which are 2.50 each, and that seems a bit overpriced. But i dont mind the cost, just wanted to make sure.

Am i right that the audio taper pots are the volume pots? Which are best for this the "Standard Dual-Gang Potentiometers" or the "Dual Miniature Potentiometers", or is there not difference. also, what is the difference between a 50k pot (for me 47k) and the 100k pot? and also, the difference between linear and logarithmic is just the progression, or is there another meaning?

would a 0.6W metal film resistor be a suitable replacement for 1/4W carbon film. it (the website) says that it is an "upgrade" but well, that is the only one i can find. also waht does the 5% in "33k 5% 1/4W carbon film resistor" mean mean, i cant really find it any where in the website.

what is the "Transistor mounting hardware". i cant really find anything of the like at maplin.

thanks again for all the help. i really appreciate it.

G-man

Finished the build now need to make it work! :)

Well I thought I would post a few pictures and hopefully get a little help. Initially I had a couple of CAP's backwards (This is my first time). I got those fixed now that I understand the freaking ovals are negative symbols (Doh!). I tried to take a few good MACRO shots as well. It is probably not the cleanest but it was what I was capable of at the time. I am getting 48VDC to the tube sockets. I am not seeing 19VDC from Q1 or Q2 though? I have the center pin going to the tube socket and I thought that should have been 19VDC. Pin 1 is going to the 48VDC from the capped switch. Anyway I tried plugging in a pair of junk headphones and all I get is a slight hum. It does not change with the volume and there is no voltage leaving the Tubes and they appear to not be on. Any thoughts or help would be greatly appreciated.

There are some larger photos located on my site.



And a sample teaser image.


Thanks

470uf for all of them. That's a common rating and will give good bass all the way down to Grados. Also, Pete says that using the 470uf's on the back side will prevent the VoIP power supply from stuttering on startup.

63V will be smaller - that's the essential difference if you go up to 100V. Some boutiques may be easier to find at 100V, but UPW's and FC's are available as 63V.

Generally speaking, polypropylene film are the best, but with interstage coupling use as in the SSMH, it may not make that much difference. Going up in rating is OK, but don't go below 0.1uf.

No. The SSMH is negatively grounded. They should have contact with the case, IMHO. That might prevent some of the random hum issues you may have read about.

Audio taper and logarithmic are generally the same, but read the fine print to be sure. Both could be used in tone or balance controls, so it's best if it says "volume". You must have "dual" for stereo.

Yes, 0.6W is fine, as is 1/4W, 1/2W, 1W, and 2W, for that matter. The percentage is a measure of the random tolerance of the resistance. 5% on a 100R resistor means it could be 95R or 105R.

Look for "TO-220 mounting kits". It's a common item.

so, 63V, 470uF. Gotcha

well, the search did not result in those, so i didnt look, but i found the polypropylene ones. will use those, thanks. the only ones available are 100V, but that i believe should not matter.

i was thinking of using a PCB for grounding, but thanks, ill use the non insulated.

thanks, so ill just go with standard dual

thats what i was thinking, the tolerance for these is 1%, so it should be ok.


i cant really find it at maplin, but i will try and find it elsewhere.

thanks again

G-man

I've got some spare MOSFET mounting hardware - send me your address in a personal message and I'll pop them in the post to you

I just finished my SS, and apart from the pot working backwards it fired up at the first try and is working wonderfully.



It's my first DIY project, so the wiring is a bit messy as I did not plan too much in advance. I did the "case" with a piece from a sheet of plexiglass, and two small pieces of an L-shaped metal bar.

At maximum volume it's loud but not unlistenable, but I have to say I'm using my Yamaha HP-3 which are pretty hard to drive. Thanks a lot to the author and everybody in this thread for a great design, and to dBel84 who assembled the BOM and shipped it to me.

Beezar has some nice ones. Sorry - I couldn't resist the plug.

G-man, I'm a little concerned at your reply on the pots: "standard dual". You must use a logarithmic or audio taper pot. All I was saying was that often the two terms are interchangeable. However, they can also be used to describe tone and balance pots, so try to get something that's definitely labeled as a "volume" pot.

Also - I forgot to mention - 50K is optimum, but 100K is probably fine in this instance. We even used 10K pots on some older Millett Hybrids, but that may be pushing it with tubes.