Zero Feedback Impedance Amplifiers

[till]

thats ok, for you, those F1 people (i doubt they can hear anything - that job must cause hearing loss) and M Schumacher, who has a face that silly, i doubt he even can spell "music".

Most of us other need to listen to real world speakers, and for those real world amps are just fine, as long as they stay somewhat below 1% or so at full output.

[PMA]

till,

do you know what is the difference between speaker distortion and solid-state distortion (spectra)? And you surely know that the distortions superimpose, there is nothing like masking of amplifier distortion by speaker distortion. And you would probably be tolerant to 1% 2nd harmonic of the speaker and not to 0.1% 9th harmonic of the amplifier.

[Upupa Epops]

Be only little bit immodestly to yourself, it's easy .

[Netlist]

I appreciate both efforts. People who aim for the nicest and smoothest sound are as valuable as the ones who try to develop a more refined product in terms of measurements. Most good designers will seek for a compromise of both. But then, we do have plenty of threads to discuss this.

/Hugo

[Upupa Epops]

Hugo, nicest and smoothest sound is not on oportunity to refined products, rather on the contrary. All is only about this thing, that some who don't know to make " refined product " still look for excuse, that worse things are good enough. It is normal human behaviour - Ezop was write two thousand years ago about Fox and sour bunch .

[B.VDBOS]

Originally posted by darkmoebius



It's too bad the balanced line receivers I've seen so far(INA134/137, SSM2015) convert the differential single back to single-ended. It would be great to use the Pro Audio approach of a line amplifier at the preamp and receiver in the Zeus in lieu of the input tranformer.

We'd get all the advantages of noise rejection and the ability to drive any length cables with extremely low distortion.

Do you think it would be possible to feed the + and - differential signals to seperate receivers in the INA2137 dual receiver pictured below and still maintain balance?


The + input for both receivers would share the common ground line of the differential cable.

Anyway, just a thought.

Thats what im going to do for a bridged amp progect using INA134 though

The input which is floating, will take a non balanced or balanced signal (or anything in between) and output a differential signal

It will have as good (even better than a single INA) CMRR even with single ended input aswell as with balanced input, dont know if this is relavent but its a very usefull circuit

[B.VDBOS]

INA2134

[extremy]

I had to ask for a visual on the windings. I'm asking about setting up the individual wire. Included is a graphic I hope is sent correctly.

Are you using a group of windings all aligned at a starting point, aligned on common center, or threaded in on a ratio? The last option I think was covered in a post about keeping the windings equal and therefore all phase correct. Although I have wondered if layering and then using a separate layer-wound concept would help.

I needed to ask about the windings. Otherwise, I can collect together most of the needed parts list from early posts.

I'm also waiting to hear of compatible preamps. This will be my only hurdle, because I'd like to use an AV unit for the preamp ( a few video inputs, and audio inputs, and control of ), and run these amps for individual channels or on active crossover setups on all channels. If cost begins to be an issue, I will probably plan for a left/right/sub configuration, instead of 5.1 or 6.1.

I, for one, wish there were a more powerful word than congratulations to Susan for the amp design.

Many thanks all,
GH

[darkmoebius]

Originally posted by B.VDBOS
Thats what im going to do for a bridged amp progect using INA134 though

The second picture that you posted is exactly what Susan described a few posts ago, but I had a hard time picturing it rom just words. Now, I get it.

I talked to one of the two engineers in charge of the INAxxx products at TI this week and he agreed that this configuration will work perfectly. Actually, he was surpised that TI never introduced a line receiver that is balanced in-balanced out.

It will have as good (even better than a single INA) CMRR even with single ended input aswell as with balanced input, dont know if this is relavent but its a very usefull circuit

I was wondering if using a balanced line receiver before the transformer actually provides better performance than feeding directly into the input transformer. (if extra gain is not needed)

I plan to use ~20 foot interconnects across my living room, so it might be a benefit.

[planet10]

Originally posted by till
IMO those are no THD figures to realy feel fear.

Earl Geddes has recently done research that shows that standard THD figures have almost no correlation to how things sound.

http://www.gedlee.com/distortion_perception.htm

dave