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DIY AMP start project - Help choosing

post #1 of 12
Thread Starter 

Hi .

 

I am new in this field of building an amp or other electronic devices but I have the enthusiasm to do it as a hobby.

I am reading some details about the circuits but I am lack of knowledge in how each component contribute to the sound/circuit and whats its porpouse. Does anyone can link me to a good guide ? Anyway, I though a good way to start is to take a well known schematics and build it and on the way to understand the inside of the amp.

I was suggested to start with low voltage amp rather high voltage as the lack of experience so I found the below kits:

Bottleneck Crack $280

Project Sunrise II $200

The Starving Student Millett hybrid $130

 

Of course that any other suggestions will be welcome but I was wondering if any of this can run even in low volume , a nice Paradigm speakers instead or headphones as I am hearing using speakers mostly.

 

Thanks.

Sagi

post #2 of 12

You really can't go wrong with any of the amps you listed.  As far as I know, these manufacturers include step by step guides w/pictures. Don't forget to look at the O2 amp. 

 

It's important to consider what headphone you are pairing each amp to.  Power, 'synergy', and coloration all play a part. 

 

I'd suggest to take a look at http://www.diyaudio.com as it's dedicated to this sort of thing. 

post #3 of 12

There are no kits for the Starving Student anymore. The only thing you have is a schematic, and you have to source the right parts yourself and build everything. If you have no clue what the stuff on the schematic is, it's probably not the best option for a first project. If you can read the schematic and know what everything is, then you could build it. No need to know why everything is there to build it. And since the starving student is so simple, once you have it built it's easy to learn how everything works together. What's more, since you have no board and have to build everything yourself, it has the potential to make you learn more than a full kit where all you do is put component A in hole A.

 

Where did you get the 130$ price tag for the starving student? It seems a bit tight. I doubt you could build it today bellow 150$, and it's very easy to drop 500$ into it if you're not careful. I know I passed the 500$ mark on my build, but mine kind of grew out of the "starving student" idea.

post #4 of 12
Quote:
Originally Posted by KimLaroux View Post

There are no kits for the Starving Student anymore. The only thing you have is a schematic, and you have to source the right parts yourself and build everything. If you have no clue what the stuff on the schematic is, it's probably not the best option for a first project. If you can read the schematic and know what everything is, then you could build it. No need to know why everything is there to build it. And since the starving student is so simple, once you have it built it's easy to learn how everything works together. What's more, since you have no board and have to build everything yourself, it has the potential to make you learn more than a full kit where all you do is put component A in hole A.

 

Where did you get the 130$ price tag for the starving student? It seems a bit tight. I doubt you could build it today bellow 150$, and it's very easy to drop 500$ into it if you're not careful. I know I passed the 500$ mark on my build, but mine kind of grew out of the "starving student" idea.

Actually, the Starving Student Millett Hybrid PCB kit sold for $120, with two matched 19J6 tubes, the custom machined case, and Cisco power supply included.

 

It's a shame that the passage of time changes things, but if there were more 19J6 tubes in the world ... we could probably do it again for that.frown.gif

SSMHamps1-360x270.jpg

post #5 of 12
Quote:
Originally Posted by Crispy808 View Post

 

I'd suggest to take a look at http://www.diyaudio.com as it's dedicated to this sort of thing. 

 

Just a small disagreement, but as good as DIYaudio is, it's decidedly not dedicated to headphone amplifiers.

post #6 of 12

Considering you only need to change a single resistor for the 12AU7 version, why did you not simply modify the kits to use 12AU7? I'm sure there's still a market for it.

 

Sure you have to modify the board for the 9 pins socket, but it's not like you had to redesign the whole chassis.

 

Are there still boards left for the 19j6 version? they could be hacked to use a 12au7....

post #7 of 12
Quote:
Originally Posted by sagi4422 View Post

Hi .

 

I am new in this field of building an amp or other electronic devices but I have the enthusiasm to do it as a hobby.

 

You can find a cheap choice by searching for "headphone amplifier kit" on Ebay. Select something around $20.  They are usually sent by air mail from China which is cheaper that something quick from UPS.  There is a software guru named Fred Brooks who advised.. "plan to throw the first one away, you will anyhow".   That seems to apply here.

post #8 of 12
Quote:
Originally Posted by KimLaroux View Post

Considering you only need to change a single resistor for the 12AU7 version, why did you not simply modify the kits to use 12AU7? I'm sure there's still a market for it.

 

Sure you have to modify the board for the 9 pins socket, but it's not like you had to redesign the whole chassis.

 

Are there still boards left for the 19j6 version? they could be hacked to use a 12au7....

Sorry, but modifying a PCB for a 9-pin socket is like re-designing the entire PCB.

 

Pins 1 and 6 are the plates on the 12AU7, whereas pins 1 and 2 are the plates on the 19J6.

Pins 3 and 8 are the cathodes on the 12AU7, whereas pin 7 is the single cathode on the 19J6.

Pins 2 and 7 are the grids on the 12AU7, whereas pins 5 and 6 are the grids on the 19J6.

Pins 4 and 5 are the heater on the 12AU7, whereas pins 3 and 4 are the heater on the 19J6.

 

It looks to me like pins 1 and 4 are the only pins that are the same.  This is a PCB we're talking about, here, and not a very complicated one at that.  Once you completely change up the pins on the tube sockets, you've completely changed the PCB.wink.gif

 

I didn't intend to get into this in detail, but maybe I should since I receive a note or two every other week on whether there are any Starving Student kits.  There are other issues besides the scarcity of the 19J6.

 

There has been some thought to bringing out a PCB for the 12AU7.  It could happen sometime in the future.  However, the 12AU7 is an entirely different tube than the 19J6's and flies in the face of the "Starving Student" principle.  The 19J6's were $1-$2 tubes when things started out.  The 12AU7's have never been that cheap and there's a school of thought that perhaps a more robust amplifier design is appropriate for a 12AU7 (there are many existing examples).  Yes, it's fine to have a point-to-point with a 12AU7 if you really want to build a Starving Student and we documented that variation for posterity on DIYForums.org.  However, basing a manufacturing run with a completely different pinout on a much more expensive/capable tube is a different matter.

 

There's also the issue of the power supply.  I hate to remind everyone, but the Starving Student with its original "surplus" Cisco power supply was/is responsible for frying a number of DACs, including up to 3 of my own.  That's another factor that has to be taken into account when investing major bucks in manufacturing runs of PCB's and machined cases that could be potentially liable for the destruction of customers' sources.  With $1-$2 tubes and a $7 power supply (another cost that didn't hold), maybe it was worth that risk.  If those costs don't hold, then maybe not ...


Edited by tomb - 12/23/12 at 1:21am
post #9 of 12

Thanks for the informative post tomb, there's nothing I can add to it. The arguments you bring make sense.

 

When I think of it now, it would be silly to redesign the kit to use the 12AU7. I often forget that the starving student was possible because the right components were readily available at a no-brainer price. With the price of the 12AU7, the MSSH lost it's original selling point.

 

You're talking about "more robust" amp using the 12AU7, mind to give a couple of examples? I'd like to see how "more robust" translate into a schematic, and if some of these are still simple enough to be built P2P. The simplicity of the MSSH is outstanding in my opinion, and I still haven't seen an hybrid amplifier design a rookie like the OP could build using P2P. 

post #10 of 12
Quote:
Originally Posted by KimLaroux View Post

Thanks for the informative post tomb, there's nothing I can add to it. The arguments you bring make sense.

 

When I think of it now, it would be silly to redesign the kit to use the 12AU7. I often forget that the starving student was possible because the right components were readily available at a no-brainer price. With the price of the 12AU7, the MSSH lost it's original selling point.

 

You're talking about "more robust" amp using the 12AU7, mind to give a couple of examples? I'd like to see how "more robust" translate into a schematic, and if some of these are still simple enough to be built P2P. The simplicity of the MSSH is outstanding in my opinion, and I still haven't seen an hybrid amplifier design a rookie like the OP could build using P2P. 

Well, I wouldn't call it silly ... just that it probably would end up being a new design on its own merits.  Once you lose the tubes and the power supply, you're pretty much into an exclusive design, especially when it comes to the power supply.  It would really lose so much of the kinship with the Starving Student that it wouldn't be fair either to Pete or to Dsavitsk (he's the potential designer and did the original 19J6 PCB design) if it was still marketed as a "Starving Student." 

 

As for the 12AU7, the SOHA, SOHA II, and CTH come to mind as hybrids.  As for Transformer or OTL tube headphone amps, the 12AU7 is probably the most predominant signal gain stage tube in existence.  Bottleheads come to mind, but there are many, many others.

post #11 of 12

If you're still interested in building a Starving Student, Fred_fred2004 designed a pcb for the 12AU7 here http://www.head-fi.org/t/503895/12au7-starving-student-finally-finished

 

I can email you a parts list with links to Mouser if you want as well.

post #12 of 12
Quote:
Originally Posted by Nixon View Post

If you're still interested in building a Starving Student, Fred_fred2004 designed a pcb for the 12AU7 here http://www.head-fi.org/t/503895/12au7-starving-student-finally-finished

 

I can email you a parts list with links to Mouser if you want as well.

And it's still in regular service beerchug.gif

 

cheers

FRED

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