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Please guide me to the right DIY amp.

post #1 of 17
11/11/11 at 8:19am
Thread Starter 

Hi guys, I really don't know much about amps and I need some help.

 

I'm looking for a DAC/amp or a DAC and an amp. The DAC will be used primarily at home and I don't want to be switching out batteries so something that runs off usb power or AC would be nice. The amp can be portable or desktop.

It will be used mostly with my HD598 and Fostex T50rp, although I have a bunch of iems as well.

 

Currently I only have a Fiio e6 which actually made some iems worse (the warmer and darker ones, Xears TDIII, Brainwavz M2) it worked great for Xears TD II and my Brainwavz B2, and kills the soundstage of the T50rp. I want something that won't kill the soundstage. 

 

I want something cheap as in less than $120ish total. I've been looking at pmillett's starving student and also looked at the O2, which doesn't have an AC option yet and I have no idea about DACs. Basically I want an alternative to E10 with DIY fun and hopefully better sound.

 

Please recommend me amps/dacs and maybe its tone/SS. Thanks guys!

 

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post #2 of 17
11/11/11 at 12:01pm

Quote:
Originally Posted by randomZash View Post

I want something cheap as in less than $120ish total. I've been looking at pmillett's starving student and also looked at the O2, which doesn't have an AC option yet and I have no idea about DACs. Basically I want an alternative to E10 with DIY fun and hopefully better sound.

 

The O2 does have an AC option. The AC adapter listed in the BOM will both charge the batteries and supply power when connected. I'm planning to build one with RCA input jacks and a 1/4" jack to put on my desktop. Currently just waiting on the PCB to show up.

 

I have an original 19J6 Starving Student but don't have any other headphone amps to reference it against.

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post #3 of 17
11/11/11 at 12:22pm
Thread Starter 

Awesome, thanks dude I missed that. I guess I should go read some more.

I know tubes need to be replaced every once in a while so the O2 might have less to deal with in the long run?

 

Let me know how they compare when you get them.

 

 

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post #4 of 17
11/13/11 at 5:36pm
Thread Starter 

a gentle bump......not a rude one.....not a rushed bump.....I waited couple of days...I can wait some morepopcorn.gif

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post #5 of 17
11/13/11 at 7:09pm
Have you built anything before? If not, a CMoy would be worth building.

I don't know the price of parts today, but the CK2III is a nice amp and an easy build. It has a transformer on board and runs off AC, too.

Also, AMB has an inexpensive DAC, IIRC. You could build it into the same case as a CK2III. That might push your budget a little, but you'd have a nice setup.

Oh, and take a look at the kits over at Glass Jar Audio. Haven't been there for awhile, but you might find something interesting.
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post #6 of 17
11/13/11 at 8:19pm

It would be self-serving for me to be specific, but there are many better options for an amp rather than an overgrown CMoy with the pot in the wrong place in the circuit (O2).  Sorry, I couldn't resist that.wink.gif

 

Uncle Erik has some good suggestions and all I can say is that there are many more in the DIY arena - DACs included.

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post #7 of 17
11/13/11 at 11:04pm
Thread Starter 

Awesomeness, I'll check into it.

 

(20min later)

That looks slightly involved, which might be fun but it would've been nice for novices like me to have a bundled kit option for everything. It seems like mouser.com is a good place for parts? Just going through the parts list is scaring me. Jesus, the frickin' face plate costs as much as a CMoy, lol. 

I might just start with a CMoy like you said. I wanted something with AC or at least rechargeable or a choice for opamps. Too bad they don't sell anymore of the penguin kits.

 

and what's this about pot?

(20min later)

Is this about the pot being before/after gain stage thing, ya? I really don't understand much, a little technical.

 

 

I've been swimming in the DIY forums for the last week and there's just so much information. Thanks for helping me navigate though. 

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post #8 of 17
11/14/11 at 7:25am


The JDS Labs Cmoy (If you buy the board for the V2.03R version) has a built in recharging circuit for rechargable 9volts. It's a pretty easy build too (Took me about 2 hours including punching the holes for the case). I've never tried it with a planar like the T50RP before though, so I cannot comment as to how well it works with it.

Quote:
Originally Posted by randomZash View Post

Awesomeness, I'll check into it.

 

(20min later)

That looks slightly involved, which might be fun but it would've been nice for novices like me to have a bundled kit option for everything. It seems like mouser.com is a good place for parts? Just going through the parts list is scaring me. Jesus, the frickin' face plate costs as much as a CMoy, lol. 

I might just start with a CMoy like you said. I wanted something with AC or at least rechargeable or a choice for opamps. Too bad they don't sell anymore of the penguin kits.

 

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post #9 of 17
11/15/11 at 1:02pm
Thread Starter 

It looks like possibly one of the best affordable Cmoys. ClieOS did a review and he mentions OPA2227 having a larger soundstage than the AD8620 (which often recommended on forums) for portable use. I think I'll try this as a starter. Thanks.

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post #10 of 17
11/15/11 at 1:07pm
Thread Starter 

on the BOM at JDS, there are different options for some of the parts. Is there anything in there that is recommended over the standard option that's worth the extra?

 

http://www.jdslabs.com/bom.php


Edited by randomZash - 11/15/11 at 5:54pm
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post #11 of 17
11/15/11 at 10:22pm
Thread Starter 
Quote:
Originally Posted by Uncle Erik View Post

Have you built anything before? If not, a CMoy would be worth building.
I don't know the price of parts today, but the CK2III is a nice amp and an easy build. It has a transformer on board and runs off AC, too.
Also, AMB has an inexpensive DAC, IIRC. You could build it into the same case as a CK2III. That might push your budget a little, but you'd have a nice setup.
Oh, and take a look at the kits over at Glass Jar Audio. Haven't been there for awhile, but you might find something interesting.

I can't seem to find that cheap DAC from AMB, the only one I found is the y1/y2. I could see how some amps are 'worth' the price for some people, but I just can't justify spending $150~$250 on a DAC. I guess I need to get used to cases being the most expensive part of these DIYs.

 

I am looking into the CK2III and it looks great. I think that'll be the next project, maybe next year. I'll research a bit more first. I'm afraid I'm gonna screw up something, plus looks like I'd need to learn how to handle some variations(power transformers etc?). 

Thanks for the suggestion.
 

 

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post #12 of 17
11/16/11 at 12:16am
Hmmm, maybe I'm wrong. But I seem to remember a popular DIY DAC that was inexpensive.

*Googles*

OK, found it. I was wrong, it wasn't AMB. It's the grubDAC over at beezar.com.

That one is in your budget and you should find a bunch of threads here about it.

As for screwing up, well, we all do. smily_headphones1.gif The good news is that DIY is fairly forgiving and you'll be able to fix mistakes. The biggest problems are simple ones, like installing a diode or cap backwards, putting in the wrong part, or a bad solder joint. Double-check polarized stuff and keep a DMM on the table to cbeck vslues before you install. Check against the build sheet, too. If you tske it slow and are methodical, you will build something that works. The biggest difference between an experienced builder and a noob is that the experienced builder will go faster.

Just go in with the attitude of "I am going to finish this." You'll do fine. And there's nothing better than having something you built work. One of life's thrills. smily_headphones1.gif
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post #13 of 17
11/16/11 at 7:05am

I sprung extra for the Nichicon "gold tune" 470uf capacitor, and WIMA capacitors for the polystyrine capacitors (the red brick looking ones). I built it with the 1/8w resistors and with a gain of 6. my highest impedance headphone is a 50~ohm Koss DJ100, and the gain is a little high, so I'm going to replace the gain resistors to make it a gain of 4, but if I had to take a random shot in the dark, I'd guess that a gain of 6 is perfect for something like your Sennheiser. I only built it with the single power transistor instead of the dual power transistors, I built it with the OPA2227, and I quite like it. I have absolutely no complaints about the sounds, I can't hear anything about it I don't "like". It's clear and spacious and balanced, the bass is strong and the highs are crisp. It's pretty much a "no flavor added" amplifier, so much as I can hear.

 

As for mistakes, everyone messes up, I sure had a few boogers on mine. I accidentally destroyed the LED resistor (I cut it off the board because  I thought I put it in the wrong place...), so I had to wire 2 10.2kohm resistors one after another to get close to the 24kohms of the original one. I also accidentally filled the hole for one of the resistors near the op-amp, and the joint for it ended up pretty ugly, but everything works great! Remember to buy some de-soldering braid, it is hundreds of times easier than trying to use a "de-soldering" tool, and it will let you undo pretty much any mistake. Just follow the instructions and it should go well, and don't be afraid to order an extra few resistors of each value, they're dirt cheap and really helpful to have around if you ruin/break/lose one!
 

Quote:
Originally Posted by randomZash View Post

on the BOM at JDS, there are different options for some of the parts. Is there anything in there that is recommended over the standard option that's worth the extra?

 

http://www.jdslabs.com/bom.php



I've never built the Grub, but you could probably stuff both the Grub and the Cmoy into a single, affordable, hammond enclosure, with USB/power in on the back, and Volume/Output/LED on the front (you'd have to connect the LED via wire leads, and then you could wire the output of the Grub to the input of the Cmoy internally). Heck, with a small circuit, you could probably use a voltage amplifier circuit to power the battery charger off of the USB supply!

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post #14 of 17
11/16/11 at 7:54am
Thread Starter 
Quote:
Originally Posted by Uncle Erik View Post

Hmmm, maybe I'm wrong. But I seem to remember a popular DIY DAC that was inexpensive.
*Googles*
OK, found it. I was wrong, it wasn't AMB. It's the grubDAC over at beezar.com.
That one is in your budget and you should find a bunch of threads here about it.
As for screwing up, well, we all do. smily_headphones1.gif The good news is that DIY is fairly forgiving and you'll be able to fix mistakes. The biggest problems are simple ones, like installing a diode or cap backwards, putting in the wrong part, or a bad solder joint. Double-check polarized stuff and keep a DMM on the table to cbeck vslues before you install. Check against the build sheet, too. If you tske it slow and are methodical, you will build something that works. The biggest difference between an experienced builder and a noob is that the experienced builder will go faster.
Just go in with the attitude of "I am going to finish this." You'll do fine. And there's nothing better than having something you built work. One of life's thrills. smily_headphones1.gif


Haha, I actually just ordered the grub. cool

 



Quote:
Originally Posted by Maverickmonk View Post

I sprung extra for the Nichicon "gold tune" 470uf capacitor, and WIMA capacitors for the polystyrine capacitors (the red brick looking ones). I built it with the 1/8w resistors and with a gain of 6. my highest impedance headphone is a 50~ohm Koss DJ100, and the gain is a little high, so I'm going to replace the gain resistors to make it a gain of 4, but if I had to take a random shot in the dark, I'd guess that a gain of 6 is perfect for something like your Sennheiser. I only built it with the single power transistor instead of the dual power transistors, I built it with the OPA2227, and I quite like it. I have absolutely no complaints about the sounds, I can't hear anything about it I don't "like". It's clear and spacious and balanced, the bass is strong and the highs are crisp. It's pretty much a "no flavor added" amplifier, so much as I can hear.

 

As for mistakes, everyone messes up, I sure had a few boogers on mine. I accidentally destroyed the LED resistor (I cut it off the board because  I thought I put it in the wrong place...), so I had to wire 2 10.2kohm resistors one after another to get close to the 24kohms of the original one. I also accidentally filled the hole for one of the resistors near the op-amp, and the joint for it ended up pretty ugly, but everything works great! Remember to buy some de-soldering braid, it is hundreds of times easier than trying to use a "de-soldering" tool, and it will let you undo pretty much any mistake. Just follow the instructions and it should go well, and don't be afraid to order an extra few resistors of each value, they're dirt cheap and really helpful to have around if you ruin/break/lose one!
 



I've never built the Grub, but you could probably stuff both the Grub and the Cmoy into a single, affordable, hammond enclosure, with USB/power in on the back, and Volume/Output/LED on the front (you'd have to connect the LED via wire leads, and then you could wire the output of the Grub to the input of the Cmoy internally). Heck, with a small circuit, you could probably use a voltage amplifier circuit to power the battery charger off of the USB supply!

 

 

Both my headphones are 50Ω and my earphones are 24~40Ω so I think I'll stick with the 4x. Considering the shipping charge I should just get some extra, probably worth it. 

JDS has a CmoyBB v2.03R rechargeable pcb board so I could do that with 2x9v nimh. I'm not sure how to do a straight usb powered unit but I'll research while I build the dac first.

 

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post #15 of 17
11/16/11 at 11:37am

For what you're using headphone wise 18v might be a little excessive. It will give you a heavier unit and I do believe it actually decreases the run time because twice as many volts sent through the same resistance means twice the current. To support that current load you would want to configure it with the two rail-splitters instead of one as well (u2&u3) instead of just using u2. This is just a guestimate, but that much current/voltage would probably not be worth it except for insensitive or high-impedence headphones. If you aren't turning the volume knob up a fair amount, you are wasting energy by boosting the signal unnecisarily.
 

Quote:
Originally Posted by randomZash View Post


Haha, I actually just ordered the grub. cool

 

 

Both my headphones are 50Ω and my earphones are 24~40Ω so I think I'll stick with the 4x. Considering the shipping charge I should just get some extra, probably worth it. 

JDS has a CmoyBB v2.03R rechargeable pcb board so I could do that with 2x9v nimh. I'm not sure how to do a straight usb powered unit but I'll research while I build the dac first.

 



 

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