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Millett "Starving Student" hybrid amp - Page 413

post #6181 of 6779

hey so I'm pretty keen to attempt this just for fun, BUT i have a few questions..

I know the answers are probably in this thread but its 400 pages long and I dont know where to start looking for them searching turns up hundreds of results and none of em really tell me what I want to know..

 

1. Is this build still worth it? 400 pages of replys must be pretty popular right but its also 4 years old has it been supersceeded?

2. how does it compare with say the project horizon? or also a manufacturer amp. eg. fiio e17?

3. the guide / parts list on the pmillet page, is it still valid? or is there an updated version I should look at? other than changing the tubes to 12au7's (seems to be the go)

4. How hard is it? I did electronics in year 11/12 and 2 1st year university electrical engineering subjects so I do have an idea. Im confident I can wire it up probably point to point with a negative rail on the side or something. but theres alot of talk about things i have no understanding of ( i never learnt about amplification), is understanding optional and just being able to wire it correctly would be enough? 

5. seriously can someone just give me a link to a powersupply i should buy? I'm really lost when it comes to this and dont know what to look for (been reading kimlaroux's posts but i think im more confused now than before)

6. I live in australia, where do i buy these parts?..

 

I really think building this would be fun mostly and maby one day drive something worthwhile one day..

 

Thanks so much for anyone who answers! :)

 

ps: I understand that the only answer might be that if have this many questions maby you shouldnt be trying this...

in the meantime im going to continue serching and reading

post #6182 of 6779
Quote:
Originally Posted by bigmac View Post

hey so I'm pretty keen to attempt this just for fun, BUT i have a few questions..

I know the answers are probably in this thread but its 400 pages long and I dont know where to start looking for them searching turns up hundreds of results and none of em really tell me what I want to know..

 

1. Is this build still worth it? 400 pages of replys must be pretty popular right but its also 4 years old has it been supersceeded?

2. how does it compare with say the project horizon? or also a manufacturer amp. eg. fiio e17?

3. the guide / parts list on the pmillet page, is it still valid? or is there an updated version I should look at? other than changing the tubes to 12au7's (seems to be the go)

4. How hard is it? I did electronics in year 11/12 and 2 1st year university electrical engineering subjects so I do have an idea. Im confident I can wire it up probably point to point with a negative rail on the side or something. but theres alot of talk about things i have no understanding of ( i never learnt about amplification), is understanding optional and just being able to wire it correctly would be enough? 

5. seriously can someone just give me a link to a powersupply i should buy? I'm really lost when it comes to this and dont know what to look for (been reading kimlaroux's posts but i think im more confused now than before)

6. I live in australia, where do i buy these parts?..

 

I really think building this would be fun mostly and maby one day drive something worthwhile one day..

 

Thanks so much for anyone who answers! :)

 

ps: I understand that the only answer might be that if have this many questions maby you shouldnt be trying this...

in the meantime im going to continue serching and reading

1. The principles will remain valid for as long as there are tubes, I suspect.  The problem is that the original 19J6 tubes have disappeared from the face of the earth in any kind of quantity to support someone making kits or PCB's and selling them to the masses.

2. I may get accused of bias, for sure, but in my experience, dual triodes are somewhat of a problem when using a single tube (just 1) for both left and right channels.   The principle of the SSMH and many other tube amps - that use dual triode tubes - tie the triodes together so that you have one tube per channel, regardless of whether the tubes inherently possess two separate circuits or not. Without going into a lengthy discussion that comes from testing literally hundreds of dual-triode tubes, IMHO, it's better if the tubes are used one-per-channel, period.

3. Yes, Pete Millett's schematic is still valid - for 19J6 tubes.  However, during the course of the SSMH, Dsavitsk designed a PCB with some improvements.  Those improvements seemed to work even with the point-to-point versions as well.  As you mention, however, the 12AU7 seems to be the way to go with the scarcity of the 19J6 tubes.  The newer version with all the tweaks is documented on the SSMH website here:

http://www.diyforums.org/SSMH/SSMHvariants.php

4. That's a highly subjective question.  Bottom line, if you can/have built a CMoy, you are probably capable of building a SSMH.

5. The 48V Cisco power supply is still valid, but you need to be careful with the DACs you may plug into it.  The Cisco power supply will fry some DACs that have little output protection, such as the Gamma 1, AlienDAC, BantamDAC or similar.  The Cisco Supply is specified in the BOM here:

http://www.diyforums.org/SSMH/SSMHbom.php

6. Farnell?


Edited by tomb - 9/7/12 at 9:54pm
post #6183 of 6779

Parts in Australia:-

 

Farnells - now Element14 free shipping if you spend over $45 - not hard to do :-)

RS Australia - Free shipping

Jaycars

Altronics

 

cheers

FRED

post #6184 of 6779

One more 12AU7 Starving Student running:

 

 

 

 

Home made PCB (thanks Fred for the layout!), Panasonic FC electrolytic caps, Icel 1uF on C2/C4, IRF510, EHX tubes, pot knob from a Cambridge Audio amp. Took me about a year to complete, including gathering the parts, making the PCB (twice, as I screwed up the first time) and getting it running.

Compared to my 6DJ8 Super Simple amp - it seems to sound a bit more detailed and precise. Really nice.

post #6185 of 6779

wow thanks heaps tomb! thats exactly the information I was after! and I didnt even know about all that info on DIY ive read most of it now and feeling alot more confident.. :)..

alright looks time to go spend some money.. fortunatly for this build not TOO much..

post #6186 of 6779
Quote:
Originally Posted by bigmac View Post

wow thanks heaps tomb! thats exactly the information I was after! and I didnt even know about all that info on DIY ive read most of it now and feeling alot more confident.. :)..

alright looks time to go spend some money.. fortunatly for this build not TOO much..

 

haha! Good luck with that. I stopped counting at around 300$... and half of the hardware I used was salvaged from used amplifiers. There's really no limit to how much money you can throw into a DIY project. You just have to figure for yourself what will be "good enough". Something that's not easy when you have no experience, and gets worse when you get into boutique parts. Heck you could easily spend 300$ per output capacitor.

 

I think anyone who goes the boutique road misses the whole "starving student" idea. I know I did. biggrin.gif

 

And yes, many thanks to tomb for answering all the questions, no matter how newb they sound.

 

As with the different tubes usable with the MSSH, I think I'll try the metal cased ones if ever I build another amp. 12SR7 if I remember correctly... They are really cheap, and I think they'll be more practical. Their metal case shields them from all the EMI in today's digital world.

post #6187 of 6779
Can anyone post their BOM for a 12au7 build. Or a link to one

Thanks
Edited by shamazo - 9/9/12 at 8:46pm
post #6188 of 6779
Quote:
Originally Posted by shamazo View Post

Can anyone post their BOM for a 12au7 build. Or a link to one
Thanks

 

This should be correct.

post #6189 of 6779
Quote:
Originally Posted by lehtinel View Post

This should be correct.

 

Don't forget the two 9 pins tube sockets, if you don't have them already. These are missing from this BOM.

 

Also, why is this BOM listing C3a and C5a as electrolytic? Usually, people use the same caps as C2 and C4, just buy 4 of them.

post #6190 of 6779
Thanks it's very helpful, I'm gonna order my parts in a couple of weeks.
Can I use any 12a 7 tube such as 12ax7?
Edited by shamazo - 9/11/12 at 1:27am
post #6191 of 6779
Quote:
Originally Posted by shamazo View Post

Thanks it's very helpful, I'm gonna order my parts in a couple of weeks.
Can I use any 12a 7 tube such as 12ax7?


You certainly can but, depending on your headphones, 12AX7's can be hard to control as they have a high amplification factor. 12AU7s are more recommendable.

post #6192 of 6779
If i changed the value of the pot or the resistors after it would I be able to use a higher gain tube to have simmiler gain as the 12au7? Just because higher gain 12a 7 tubes are significantly cheaper.
post #6193 of 6779
Quote:
Originally Posted by shamazo View Post

If i changed the value of the pot or the resistors after it would I be able to use a higher gain tube to have simmiler gain as the 12au7? Just because higher gain 12a 7 tubes are significantly cheaper.

 

I originally built mine because I had 12AX7 in stock. After a few days of testing, I ordered a pair of 12AU7A.

 

You can lower the total "gain" of the amplifier by using higher values resistors before the pot, but this method doesn't really lower the gain, it just attenuates the input signal. The problem is that the tubes themselves have a fixed gain, and they amplify any noise in the circuit. So if you have a constant background noise, and that you attenuate the input level, you're basically lowering the Signal-To-Noise ratio. In real life, this means you'll have even more background noise with a high-gain tube than you'd have with a mid- or low-gain tube.

post #6194 of 6779
Quote:
Originally Posted by KimLaroux View Post

Quote:
Originally Posted by shamazo View Post

If i changed the value of the pot or the resistors after it would I be able to use a higher gain tube to have simmiler gain as the 12au7? Just because higher gain 12a 7 tubes are significantly cheaper.

 

I originally built mine because I had 12AX7 in stock. After a few days of testing, I ordered a pair of 12AU7A.

 

You can lower the total "gain" of the amplifier by using higher values resistors before the pot, but this method doesn't really lower the gain, it just attenuates the input signal. The problem is that the tubes themselves have a fixed gain, and they amplify any noise in the circuit. So if you have a constant background noise, and that you attenuate the input level, you're basically lowering the Signal-To-Noise ratio. In real life, this means you'll have even more background noise with a high-gain tube than you'd have with a mid- or low-gain tube.


Great explanation, I'll spend more to get the 12au7s then. Rep coming when I get to my computer.
post #6195 of 6779
Quote:
Originally Posted by KimLaroux View Post

 

I originally built mine because I had 12AX7 in stock. After a few days of testing, I ordered a pair of 12AU7A.

 

You can lower the total "gain" of the amplifier by using higher values resistors before the pot, but this method doesn't really lower the gain, it just attenuates the input signal. The problem is that the tubes themselves have a fixed gain, and they amplify any noise in the circuit. So if you have a constant background noise, and that you attenuate the input level, you're basically lowering the Signal-To-Noise ratio. In real life, this means you'll have even more background noise with a high-gain tube than you'd have with a mid- or low-gain tube.

Kim,

    what phones do you use? I have some HD-600 and the gain is a bit low on my last build. I think I could benefit from a 12AX7...

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