[Tomo]

Yeah,

Rick just told you all the reason why I cancelled my "balanced Szekeres" project.

Anyways, in PassDiy's Son-Of-Zen type (or MOSFET differential amp), can made to accept UNBALANCED inputs. You can simple connect one of the input to ground. Note this will effectively kill any advantage of building BALANCED version. ... Yeah crap. ...

Instead what you want to do is to build a UNBALANCED-to-BALANCED converter. This is fairly easy with a single opamp.

Also, there is another thing you can try. Observe the original Szekeres amplifier schematics. You may be able to take signals from DRAIN and SOURCE of the MOSFET to get the BALANCED output. But I cannot confirm this.

Tomo

P.S. About fire hazard thing, you can ask Mr. Corleone to "take care" of the problem at his birthday party. According to the movie, Godfather can be very "persuasive" if he wants to be. ...

 

[DigiPete]

Quote:

Originally Posted by a1rocketpilot Wow, thanks for all of the information! Better start reading up (unfortunately, can't build anything in the dorms, some crap about fire safety or something... )

You can always beg for forgiveness...

 

[a1rocketpilot]

Quote:

Originally Posted by Tomo Instead what you want to do is to build a UNBALANCED-to-BALANCED converter. This is fairly easy with a single opamp.

Hmm, interesting, how may I go about doing this? I didn't see anything on Headwize about this. Would this in effect create a balanced source?

 

[Tomo]

This is an example. I NEVER tried it.

http://sound.westhost.com/project51.htm

T

 

[00940]

Quote:

Originally Posted by a1rocketpilot Hmm, interesting, how may I go about doing this? I didn't see anything on Headwize about this. Would this in effect create a balanced source?

buy a pair of drv134, it's easier, cheaper and better than doing it with common opamps. Or perhaps a pair of opa1632 but they're a bit harder to work with.

 

[a1rocketpilot]

Quote:

Originally Posted by Tomo This is an example. I NEVER tried it. http://sound.westhost.com/project51.htm T

Is there a particular reason why you never tried it?

 

[nikongod]

hey a1, if youa re looking for a CHEAP balanced amp, here ya go:

cheap balanced amp. costs like as much as 2 buffered cmoys...

 

[Tomo]

Hey,

It is not that I dislike Mr. Elliot's work. In fact, I love his work and would never hesitate to refer to him.

It is just that I was a grad student and didn't have cash. Now I have even better excuse ... called 74HCU04's. You can wire this to get UNBALANCED-to-BALANCED converter with amplification enough for a can.

The dude was crazy enough to stack dozens of these to drive a speaker. Hehe. May not be audiophile, but it certainly is cool.

Tomo

 

[a1rocketpilot]

Either way, this will provide a true balanced source wouldn't it? Or does it need to be created in the Digital>Analog conversion stage or before?

 

[nikongod]

Quote:

Originally Posted by a1rocketpilot Either way, this will provide a true balanced source wouldn't it? Or does it need to be created in the Digital>Analog conversion stage or before?

both schematics above (the picture in this thread, and my thread) will balance a single-ended signal. its hotly debated (perhaps i just missed the end of the debate) weather an opamp based system is as good as a balancing transformer, or a discrete system....

 

[rickcr42]

Quote:

its hotly debated (perhaps i just missed the end of the debate) weather an opamp based system is as good as a balancing transformer, or a discrete system....

the "transformers suck" camp usually bases their opinion totally on the measuring and theoretical side of the coin while those who actually listen mostly fall on the transformers rule side.This is not 100% but very close to.Take out he powering requirements,as in NONE for the tranformer option and the same part can be used with any audio circuit from a battery operated one all the way up to a tube amp running at 500VDC without a single change

expensive suckers though

 

[nikongod]

Quote:

Originally Posted by rickcr42 the "transformers suck" camp usually bases their opinion totally on the measuring and theoretical side of the coin while those who actually listen mostly fall on the transformers rule side.This is not 100% but very close to.Take out he powering requirements,as in NONE for the tranformer option and the same part can be used with any audio circuit from a battery operated one all the way up to a tube amp running at 500VDC without a single change expensive suckers though

i know, i just bought a pair

i now need to get off of my bumm, and select an amp to "drive" with them...

 

[a1rocketpilot]

So if I want to create a DIY balanced setup, would it be something like this:

Music>DAC>Unbalanced-Balanced Converter>Balanced Amp>Balanced Headphones

Or should I just save up for a few more years and get a true balanced source and a balanced Dynahi or M3 or SDS or what not? (hopefully by then I will have figured out what I like in terms of amping)

 

[00940]

The circuit linked by Tomo on ESP website is as basic as it gets. There's a better unbalanced to balanced converter however here : http://sound.westhost.com/project87.htm , fig 3.

It is more complex. But at the risk of sounding like a broken record, it is exactly the same topology as used in the DRV134. The good thing with the DRV134 is that everything you need but bypass caps are in the chip and that the critical resistors are /very/ accurate. All this for the cost of one decent opamp.

If you want to know everything about unbalanced to balanced line drivers go page 67 here : http://www.analog.com/library/analog...h6_final_I.pdf

edit : the ssm2142 in Jung's book is about the same thing as the DRV134. The part from TI has slightly better specs though.

 

[a1rocketpilot]

Thanks for the heads up on the DRV134, but a couple of questions. On the schematic, what is +Sense and -Sense? Also, where and why would you need the bypass caps that you mentioned?