DIY Balanced amp for Edition 9

[steaxauce]

So, this will be my first DIY job (besides modding the X-10v3, but that was pretty minor), but I want you to forget that right now. I plan on going all out! I'll be using it with a Lavry DA10 and an Ultrasone Edition 9. I considered just buying something like a GS-X, but decided I wanted the experience of building an amp myself. I'd like to know which of the designs you guys think would be best for me to consider. It definitely needs to be solid state. The amp will be used solely for driving the Edition 9, which has an impedance of 40 ohms. I want to pull out as many of the stops as I can, but don't want to spend more than a couple thousand dollars. Any input is appreciated!

 

[Killercrush]

Why not build a 6-channel balanced Beta22 ?

 

[nikongod]

just buy it.

the few amps that are worthy of that price tag are worthy of that price tag not only because they sound like whoa (and solid state too!) but because they have tons of tiny parts that are impossible to see weather they are in forwards or backwards after being individually mated into pairs... to say the least, its a pain in the bumm to build one.

call up whoever you like who builds one of these beasts and drop a couple clams.
headroom, headamp, singlepower, and ray samuels come immediately to mind.

a multi-thousand dollar amp is a pretty poor second project IMHO.

 

[jcx]

Quote:

Specs for Edition 9: Closed-back headphones Black Chrome plated ear cups PROline standard ULE by Mu Metal shielding Dynamic principle Frequency range 8Hz-35.000 Hz 40 mm Titanium-Mylar drivers Impedance 30 ohm SPL 96 dB ...

"all out" in my book is 120 dB spl with a little headroom, call it 500 mWrms

5.5 Vpk, 180 mApk

"Standard" - but very good approach: 4 channels of buffer in high quality op amp loop amplification, easy enough

going balanced the drive V is split between the 2 sides of the amp, I would still probably go for+/-5 V supplies just because of the greater availiblity of op amps speced to work at that supply V

Class A output buffer has to be on the "all out" list, you could try my op amp version - circuit ideas spread thru http://www.head-fi.org/forums/showthread.php?t=190991 in my (jcx) posts

but Class A "diamond buffer" is probably simpler for non-engineers to design - at 100 mA bias * 5V = 500 mW power dissapation TO-126 or TO-220 power transistors wouldn't need extra heat sinking, TO-92 could be paralled like Gilmore's Class A output for a little safety margin with the all plastic packages

lots of parts may make it a rather drawn out protoboard project, maybe look for multiloop circuit boards and just box 2 together, 1 for each channel

dual GilmoreLite's would be an all discrete approach

you also have to determine wether you are going to balanced source exclusively or will need some phase splitter/inverter to convert common single ended input

 

[d-cee]

a couple of grand is a lot of money for DIY

can only think of a fully pimped out 6 channel b22 + psu

or kevin gilmore's new/upcoming FET based amp

 

[balou]

I'm curious.. six channels? I know 2,3 and 4 channel designs, but how do you wire 6 channels together?

 

[d-cee]

no i'm pretty much dumb

i dont think you can do 6 channels

balanced doesn't share a common ground

 

[amb]

The "6-channels" refer to a combined 4-channel fully-balanced and dual 3-channel active ground unbalanced amp, utilizing a total of six β22 boards. See the "other options" section at the β22 website.

 

[swt61]

I also agree that the six channel balanced β22 is the right choice, but as Nikongod stated it's no begginer project. There are a few members building these, and that would be my recommendation.

 

[d-cee]

Quote:

Originally Posted by d-cee /img/forum/go_quote.gif no i'm pretty much dumb i dont think you can do 6 channels balanced doesn't share a common ground

Quote:

Originally Posted by amb /img/forum/go_quote.gif The "6-channels" refer to a combined 4-channel fully-balanced and dual 3-channel active ground unbalanced amp, utilizing a total of six β22 boards. See the "other options" section at the β22 website.

omg! before i editted it out i was sort of on the right track

//slashes wrists

 

[threEchelon]

Quote:

Originally Posted by amb /img/forum/go_quote.gif The "6-channels" refer to a combined 4-channel fully-balanced and dual 3-channel active ground unbalanced amp, utilizing a total of six β22 boards. See the "other options" section at the β22 website.

What about using only four boards and balanced to unbalanced transformers? How do you think the would sound compare to a 3 channel configuration?

Also, if you had a six board configuration and connected a single ended headphone to the R-, L-, and G, would the headphones be out of phase?

 

[amb]

Quote:

Originally Posted by threEchelon /img/forum/go_quote.gif What about using only four boards and balanced to unbalanced transformers? How do you think the would sound compare to a 3 channel configuration?

If you're converting the balanced signal to unbalanced then the amp would only need to be 2-ch passive-ground or 3-ch active ground. You don't need 4 boards for that.

Quote:

Also, if you had a six board configuration and connected a single ended headphone to the R-, L-, and G, would the headphones be out of phase?

If you're driving the amp with balanced inputs, yes, the two sets of unbalanced headphones would be out-of-phase relative to each other, but not between channels. It's a topic of debate whether true absolute phase is audible or not (i.e., many amps invert the phase, such as the Millet Hybrid, but when was the last time you heard someone complain about that?).

If you drive the two sides of the 6-ch amp with separate unbalanced sources, then the amp is effectively two separate 3-ch active ground amps in the same chassis, sharing a volume control knob.

 

[steaxauce]

Thanks for all the input, guys. It sounds like the 6-channel Beta22 is for me, but I'm not understanding how it works. I thought balanced amps didn't have grounds; that the ground was replaced by an inverted channel which was like an active ground for that channel? Anyway, I'm reading about it.

I appreciate the people who've said it's not a good idea for me to start out with a project like this, but I do believe this is the best way for me to get into DIY. As of now, my experience with electronics consists of a single semester of calc-based Electricity & Magnetism at my university. I don't know about the designs that are currently out there and have very little experience with soldering, but I understand a lot of the principles behind this stuff, and I think I'll be pretty quick in picking things up.

 

[robm321]

Quote:

Originally Posted by nikongod /img/forum/go_quote.gif just buy it. the few amps that are worthy of that price tag are worthy of that price tag not only because they sound like whoa (and solid state too!) but because they have tons of tiny parts that are impossible to see weather they are in forwards or backwards after being individually mated into pairs... to say the least, its a pain in the bumm to build one. call up whoever you like who builds one of these beasts and drop a couple clams. headroom, headamp, singlepower, and ray samuels come immediately to mind. a multi-thousand dollar amp is a pretty poor second project IMHO.

Agree 100% - I always see these threads and then hear nothing about it down the road. I don't doubt that people end up spending money and end up with a pile of unfinished nothing at the end. It's a long painful process to build these unless you do it as a hobby. My Aleph 3 was built by a guy from Audiogon that is renowned for all his DIY projects. He's an expert and it sounds exactly like the Pass Labs amp (which is the idea), but for me to do the same would be much more difficult to pull off. The money you save in the end may not be worth it unless you really just want to be a electronics DIY guy and can put up with the fact that things don't go according to plan over and over again.

 

[RasmusseN]

get a b22 there sweet kills GS-X IMO