[Banfi T.]

Quote:

Originally Posted by amb I think I'd elaborate on that a bit. One of the benefits of going balanced is that it prevents the high current ground return from the headphones from polluting the input signal ground. Since the M³ in unbalanced form employs a three-channel active-ground topology, it is already immune from this phenonmenon. Thus, to this end a balanced M³ isn't going to offer the same improvement over an unbalanced M³ like you would with a conventional passive-ground amp. However, going balanced also gives you double the output voltage swing and four times the output power. For those who have low efficiency or super-high impedance headphones (such as the AKG K1000) or those who just want gobs of reserve power, there is still an impetus for a balanced M³. WIth a capable power supply and sufficient heatsinking of its output MOSFETs, a balanced M³ can output 20Wrms of power into 8Ω per channel, and that's enough power to rock a house with efficient speakers.

Also, balanced operation reduces distortion 10-20 times depending on the matching of the amplifiers. Noise floor is also significantly lowered and the transient impulse behavior is better too. So there could be significant difference in my opinion.

I did built triple mono headamps before and found the balanced version (with the same amplifier moduls) better. But to tell the thruth I got the best results with inherently balanced designes (not four amplifier, but two balanced).

Also, the third (ground channel) is good for better driving and lower noise floor but the returning current from the two drivers are "meeting" there, and thus interacting with each other. Of course this is not a big problem with very low output impedance and high current sinking capacity, but there is a theoritical limit which is not present with balanced circuits. Plus, to provide the lowest possible output impedance you have to use strong negative feedback, which is a more tricky thing to do right then to build a good sounding NFB amp (with obviously higher output impedance). A balanced NFB amp however is not facing with this problem (Outoput impedance can be higher, since the the returning currents are not "meeting" anywhere).

Errr...sorry for the long post

 

[Alwayswantmore]

I'll add two more products to the list...

1.) Direct connect to most Wadia CDPs
2.) The Ayre V-3 power amp, which I'm currently using to drive K1000s.

Note: There has been so much discussion about what constitutes a balanced amp. I was curious enough on this point to contact the company that manufactures my V-3. Charles Hansen, Ayre's Founder and Designer, was gracious enough to personally respond. He also gave me permission to publish his response...

Hello Kent,

1. Does Ayre V-3 with K-series update use any negative feedback (when used in balanced mode)?

No. All of our products are zero-feedback, including even the power supply regulators.

2. What is the mode of operation?

High-bias class AB. (With a 120 ohm load, the amplifier will remain in class A up to the full voltage swing of the amplifier.)

3. Will driving the K1000 (dynamic drivers; 120 Ohms; relatively high efficiency) have any impact on product performance / reliability? [Note: I also use a Vandersteen 2W with Vandersteen´s balanced crossover - the 2W also connects to the speaker outs on the Ayre - the crossover is placed between the line-stage and amp-in.]

There is no problem with the load impedance. However, keep in mind that the outputs of all Ayre amplifiers are balanced. Connecting a load with a common ground (such as most headphones) will at the very least blow a rail fuse, and may damage the amplifier. Using the Vandersteen crossover will roll off the bass output from the amplifier, and the requires compensation in some other method. It sounds like you are using the acoustic output from the subwoofers to augment the headphones. This would not work with sealed headphones, but should be fine with open-air type headphones. (I have never tried it.)

4. In the world of headphones, a balanced headphone amp drives an ungrounded balanced signal (i.e. the signal driving headphones is inverted for the `negative´ side). Are the speaker output connections on the V-3 balanced?

Yes. The AKG K1000 will work with balanced amplifiers (such as Ayre) as there are four separate connecting wires. However, most headphones have three-wire connections and cannot be used with balanced amplifiers.

Best regards,
Charles Hansen

 

[Cronstead]

New kid on the block: SFT-Audio GXDM.

 

[Bovine]

How abt RP1000?