Metrum Octave Dac - What are the Chips used

[ThorstenL]

Guys,

Originally Posted by Ken Newton

If you go back and correctly read what I wrote, and the context in which I wrote it...

Let's all take a chill pill and look at the facts.

In the end, if someone likes the sound from Transistor Amp's or Tube SE, from Non-Os CD or for SACD, it is their choice and there is neither the need to become defensive about one's choice if it criticised or let things degenerate into name calling.

The technical facts are well documented, but as we all know, traditional measurements and "modern"technical features do not reliably produce good sound.

So please, "de gustibus non disputandum est".!

Let's get back to observed facts.

Ciao T

[Salas]

Guys, chill out on the personal calls stuff. Some such posts removed.

[jitter]

Hey guys, don't let a little slap on the wrist keep you away from this thread...

Originally Posted by Ken Newton

Below, is the link to a rather interesting hobbyist review comparing the Lamipzator DAC level-4 to the Metrum Octave.

The Audio Eagle - DAC_Comparison / Does Digital Finally Rock?

I found this an interesting read. It's remarkable how much a no-frills design as the Octave can achieve for so little... I mean, a very straight forward layout without esoterics, and yet almost all the way up there with the lampizatOr according to the reviewer. And this lampizatOr too is a NOS DAC that seems to be in "overwhelming demand". I'm wondering how long it'll take the big boys to catch up on this...

Now that my Octave has had nearly a week's worth of burn in, I'm pleased to say that the sound is maturing like a good wine. The wonderful sound of this DAC keeps me digging up CDs I haven't heard in a long time, a very good sign.
I'm guessing another week of burn in and it's fully matured...

[Ken Newton]

Originally Posted by jitter

Hey guys, don't let a little slap on the wrist keep you away from this thread...

It's not the wrist slap. It's that the wrist slap appears to be oddly unilateral. qusp's Comment #298, which contains the most ugly insult of any said here, inexplicably remains undeleted by Salas.

[Salas]

I can't be following and evaluating the whole thread each time a single report comes to the reports que. Remember guys, report what is objectionable or it may slip. The big picture contains hundreds of active threads, the mods are few plus they can't possibly be on-line all together at a given time or omnipresent.

*298's gone too.

[Ken Newton]

Originally Posted by Salas

I can't be following and evaluating the whole thread each time a single report comes to the reports que. Remember guys, report what is objectionable or it may slip. The big picture contains hundreds of active threads, the mods are few plus they can't possibly be on-line all together at a given time or omnipresent.

*298's gone too.

Thanks, Salas. I hadn't considered the possibility that my comment had been reported, while the provocative comment of another here had not been.

[Ken Newton]

Originally Posted by jitter

I found this an interesting read. It's remarkable how much a no-frills design as the Octave can achieve for so little...

From a features standpoint, what I find interesting about the Metrum, aside from NOS, is that the DAC chips (assuming they are, DAC8580) require no I/V or putput stages. The datasheet for the DAC8580 says it has an 18 ohm output impedance and can deliver +/- 25mA. There are four of these per channel in the Octave. Having such a robust analog output stage integrated right in to the DAC8580 may also be a key to the sound of the Octave.

[pieter t]

Originally Posted by Ken Newton

From a features standpoint, what I find interesting about the Metrum, aside from NOS, is that the DAC chips (assuming they are, DAC8580) require no I/V or putput stages. The datasheet for the DAC8580 says it has an 18 ohm output impedance and can deliver +/- 25mA. There are four of these per channel in the Octave. Having such a robust analog output stage integrated right in to the DAC8580 may also be a key to the sound of the Octave.

My Octave manual specifies output impedance of the dac being 82 ohm.
Based on this spec I doubt the dac chips being 8580's; four of these in parallel should yield an output impedance of some 5 ohm.

[Ken Newton]

Originally Posted by pieter t

My Octave manual specifies output impedance of the dac being 82 ohm.
Based on this spec I doubt the dac chips being 8580's; four of these in parallel should yield an output impedance of some 5 ohm.

What is typically done when paralleling low impedance sources is to place a resistor in series with each output. This is done so to suppress any tendency for the low impedance voltage sources to fight each other. With a 82 ohm net output impedance, a 310 ohm resistor would be in series with each of the four DAC8580 outputs - assuming, the Octave, indeed, does utilize the DAC8580.

[jitter]

Originally Posted by pieter t

My Octave manual specifies output impedance of the dac being 82 ohm.
Based on this spec I doubt the dac chips being 8580's; four of these in parallel should yield an output impedance of some 5 ohm.

The outputs of the DAC IC's are not directly coupled to the RCA connector, but through 330R resistors.

Passage from the 6 moons review of the Octave:

"These chips were designed to drive 75Ω loads so there's no need for any output buffer. In the Octave you have 4 chips per channel working in parallel. 8 chips total are connected by eight 330Ω resistors to create an output impedance of 82.5Ω."

Edit: apparently the output impedance of the DAC-IC's is disregarded in the quote. 4x 330R resistors in parallel calculates exactly 82R5.
Edit 2: with 18R+330R x4 parallel calculates as 87R. Measurement of DC resistance is hampered by a slight DC-offset (5-6 mV) on the output so I measured resistance both ways around (core/shield) and averaged the two to get 88R7. Minus measurement lead resistance of 0R6 gives 88R1. Very close to the calculated 87R, if you keep the usual tolerances in measurements and components in mind, the DAC8580 still seems to be the most likely answer.