Transporter, Inside Out

[seanadams]

would have guessed it would have been a discrete component design given the price.

how would that be better?

[Chaka]

Hi Sean- No, I can't claim it would be but historically many find discrete stages sound better than opamps, but its a long debated thing that I amn sure you are fully aware of. Nice unit you got there btw, congrats!!! Hope to hear one some day.

[Wombat]

I am no DIY person.
Can you directly replace the OP? Are they perfect substitues?

The OPA627 isn´t that critical. There are parts with utopic high bandwiths that would need a different layout.
So it should work as direct replacement.
Btw. i´d expect something different from a 2000$ device. Even 200$ PC soundcards have more expensive OPs in the exit.
Its hard to argue against the 5534 but you won´t find it in actual so called High-End gear i believe.

[pfarrell]

> Chaka;140042 Wrote:
>>would have guessed it would have been a discrete component design given
>>the price.

No, to get into serious audiophile pricing, Sean and company would have
to at least double it, maybe add a zero.

seanadams wrote:
> how would that be better?

I'm not Chaka, so I'm just butting in.

In the audiophile world, there are magic quality points for having an
all discrete class A design. Ignoring the minor fact that the design
class (A, B, AB, etc.) has little to nothing to do with sound. But since
A versus B versus D was important in high school and college grades, it
must be true of circuit topologies as well.

Discrete has to be better, because hand soldering in components with
variances in many parameters has to be better than using a chip.

Some of these same beliefs are also totally accepted in the recording
industry.

At least the recording engineers don't buy into the claim that point to
point wiring is always better than PCB traces.


--
Pat Farrell PRC recording studio
http://www.pfarrell.com/PRC

[Chaka]

Ha ha, I like the sarcasm. I am far and away not an expert on circuit design and don't know enough about opamp vs. discrete, I was just pointing out an observation so I can't add to the argument. I have a DAC that totally kicks butt and it has an opamp analog stage. Just an observation is all.

[pfarrell]

Chaka wrote:
> Ha ha, I like the sarcasm. I am far and away not an expert on circuit
> design and don't know enough about opamp vs. discrete, I was just
> pointing out an observation so I can't add to the argument.

Well, part of it is true. Many Audiophiles and so-called Recording
Engineers swear that there is a huge difference, and that Class A is
clearly superior.

A little of it even has a basis in engineering. A "class A" design has
no zero crossing distortion. A "class B" design essentially takes two
half-amplifiers, one for the positive signal and one for the negative,
and combines them. The obvious advantage over a Class "A" design is that
when no music signal is flowing, no current flows, and no greenhouse
effect. But some folks claim that the joining of the two signals is
never perfect and can be heard. It is usually very easy to tell of a
component is Class A, it will be warm to the touch even when idling.

The discrete versus PCB arguement has equally vocal supporters on each
side. Just check out any The Absolute Sound review of something with
hand wired, point-to-point connections. It will "remove a veil" and all
sort of great things.

And crappy layout of the PCB (as with hand wiring) can lead to many sins.

Part of what makes something "audiophile" is the claim that the design
was made without economic compromises. Hence all the $10,000 CD players,
and $50,000 amplifiers. But all engineering is design the most quality
or whatever other "best" definition you want, for the least money. The
good engineers deliver very good quality for a reasonable price. Exactly
what is 'reasonable' is left to the reader.

But it really is all about the music.

--
Pat
http://www.pfarrell.com/music/slimse...msoftware.html

[occam]

Sean,

Thanks for the reply. Given your choice of dac and ouput chips -

1. Is each output phase/channel produced by a single 5534 recieving both phases of that channel from the dac. The other output phase is produced by the same but with the output phases of the dac chip reversed for input into the other opamp?

2. Given the bipolar input opamps, the outputs from the opamps are cap coupled?

3. Are to ouputs from the dac (inputs to the opamps) cap coupled or do they rely on common mode offset rejection?

TIA,
Paul

[seanadams]

// 1. Is each output phase/channel produced by a single 5534 recieving both phases of that channel from the dac. The other output phase is produced by the same but with the output phases of the dac chip reversed for input into the other opamp?

No, it is separate (one amp per phase per channel) from the DAC to the XLRs. Then a further active balun stage drives the RCAs from there.

// 2. Given the bipolar input opamps, the outputs from the opamps are cap coupled?

No, except for a 100R series resistance, the output comes straight off the op amps.

// 3. Are to ouputs from the dac (inputs to the opamps) cap coupled or do they rely on common mode offset rejection?

Those are cap coupled to 0v.

[Walleyefisher]

Sean - Looks like a clean design...very nice. Congrats I can't wait til mine shows up.

Will there be an hardware upgrade path for the Transporter? Looks like there is plenty of room for a daughter board or three. LOL

[WSLam]

Hi Sean- No, I can't claim it would be but historically many find discrete stages sound better than opamps, but its a long debated thing that I amn sure you are fully aware of. Nice unit you got there btw, congrats!!! Hope to hear one some day.

Maybe Sean's engineering has rewrote audio history! =) Listen with an open mind!