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Matrix Quattro amp: unboxing and initial impressions - Page 9

post #121 of 229
Quote:
Originally Posted by Loquah View Post
 

The dual op amp seems to be purely for colouration of the sound. The amp works using XLR, RCA, balanced and unbalanced outputs even when the dual op amp is removed.

 

An Op Amp doesn't really add colouration in the way tubes add colouration, do you mean some tone control function?

 

I got so curious that I sent an e-mail to Matrix to see if they would tell me how this amp works, some kind of circuit diagram might be nice.

post #122 of 229
Quote:
Originally Posted by Chris J View Post
 

 

An Op Amp doesn't really add colouration in the way tubes add colouration, do you mean some tone control function?

 

I got so curious that I sent an e-mail to Matrix to see if they would tell me how this amp works, some kind of circuit diagram might be nice.

 

To me "colouration" is tone control - anything that alters the signature of the amp (which op amps do) is adding some sort of "colour"

 

Let us know what you receive back. It'd be really interesting to know what the designers intended.

post #123 of 229
Quote:
Originally Posted by Loquah View Post
 

 

To me "colouration" is tone control - anything that alters the signature of the amp (which op amps do) is adding some sort of "colour"

 

Let us know what you receive back. It'd be really interesting to know what the designers intended.

 

Op Amps aren't like tubes, designers don't add them into circuits to add colour.

They would use an Op Amp for:

EQ

convert Balanced into SE

as a buffer

as an amplifier,

DC servo

etc

etc

post #124 of 229

And here's what Matrix said about the circuitry in the Matrix Quattro Headphone Amp:

 

Hi Chris,
 
The dual Op Amp of Quattro AMP is BB OPA2604.
We are so sorry, we can not provide a circuit diagram or schematic to you.
 
Best regards.
post #125 of 229
Gee... that's useful!!??
post #126 of 229

Yes, very useful......:rolleyes:

 

You gotta respect a company like Bryston.

You can download their schematics right off their website.

post #127 of 229
Quote:
Originally Posted by Loquah View Post

Gee... that's useful!!??

 

I rephrased the question (I asked the question again), here's how they responded:

 

"Hi Chris,
 
Through the op-amp (OPA2604) to produce a negative phase of the signal, and then amplification, then amplifies the same phase input signal and negative phase signal, this will get a balanced output.
 
Best regards."

 

 

In other words, the OPA2064 is used to create an inverted version of an SE input.

So the original version of an SE input is used to drive the Non-Inverting (i.e. +ve) output amp, and the inverted version of the original SE input is used to drive the Inverting output amp (i.e. -ve).

post #128 of 229
Quote:
Originally Posted by Chris J View Post
 

 

I rephrased the question (I asked the question again), here's how they responded:

 

"Hi Chris,
 
Through the op-amp (OPA2604) to produce a negative phase of the signal, and then amplification, then amplifies the same phase input signal and negative phase signal, this will get a balanced output.
 
Best regards."

 

 

In other words, the OPA2064 is used to create an inverted version of an SE input.

So the original version of an SE input is used to drive the Non-Inverting (i.e. +ve) output amp, and the inverted version of the original SE input is used to drive the Inverting output amp (i.e. -ve).

 

So why does it work without the dual op amp?

post #129 of 229

The dual Op Amp drives the inputs of the Inverting headphone "power amps"(-ve output pin on the headphone jack).

So if you remove the dual Op Amp there will be no signal at the input of the inverting amp.

But the input should still have a ground reference so the output of the inverting amp will be zero, i.e. signal ground, it will act similarly to the ground (i.e. black) connection on a power amps output.

 

Try this:

listen to a balanced headphone without the dual Op Amp.

Now try again, but using the dual Op Amp.

The volume should go up a bit, by approx. 6 dB.

 

Just make sure you turn the Quattro amp off before you pull the Op Amp out or put it back in.

post #130 of 229
Quote:
Originally Posted by Chris J View Post
 

The dual Op Amp drives the inputs of the Inverting headphone "power amps"(-ve output pin on the headphone jack).

So if you remove the dual Op Amp there will be no signal at the input of the inverting amp.

But the input should still have a ground reference so the output of the inverting amp will be zero, i.e. signal ground, it will act similarly to the ground (i.e. black) connection on a power amps output.

 

Try this:

listen to a balanced headphone without the dual Op Amp.

Now try again, but using the dual Op Amp.

The volume should go up a bit, by approx. 6 dB.

 

Just make sure you turn the Quattro amp off before you pull the Op Amp out or put it back in.

 

Cool. Thanks for the explanation!

post #131 of 229
Quote:
Originally Posted by Loquah View Post
 

 

Cool. Thanks for the explanation!

 

I asked Audio GD how their balanced headphone amp, the NFB-6 works.

 

They sent me a block diagram.

No confusion there!

 

Here it is, Audio GD NFB-6 block digram:

 

post #132 of 229

I've received some OPA627s today for the Quattro, but they're on the A-Class adapters designed for the M-Stage. Can anyone tell me if the A-Class modification (resistors across 2 pairs of pins) will alter the OPA627's performance in the dual op amp slot?

post #133 of 229

I just fried my Quattro!!!

 

I got careless and inserted the dual op amp the wrong way around and magic smoke came out! I think C61 cooked (small red cap to the left of the large nichicons) which appears to be a bypass cap. Would that make sense?

 

The amp still works so I'm guessing that's what's happened, but would love it if someone can confirm my logic. Also, what are components BR1 and BR2?

post #134 of 229
Quote:
Originally Posted by Loquah View Post

I've received some OPA627s today for the Quattro, but they're on the A-Class adapters designed for the M-Stage. Can anyone tell me if the A-Class modification (resistors across 2 pairs of pins) will alter the OPA627's performance in the dual op amp slot?

From what I understand of the circuit description, modifying the OPA627 to Class A will only alter the sound coming out of the inverting outputs (I.e. the negative outputs or "cold" outputs).
post #135 of 229
Quote:
Originally Posted by Loquah View Post

I just fried my Quattro!!!

I got careless and inserted the dual op amp the wrong way around and magic smoke came out! I think C61 cooked (small red cap to the left of the large nichicons) which appears to be a bypass cap. Would that make sense?

The amp still works so I'm guessing that's what's happened, but would love it if someone can confirm my logic. Also, what are components BR1 and BR2?

The little red ones are between the big Nichons and BR1 and BR?
Probably a bypass cap on the outputs of BR1 and BR2.
I'm quite surprised that it smoked!

I would store the dual amp you smoked in the garbage. redface.gif

BR1 and BR2 are next to the little tin box?
They would be bridge rectifiers for the Power Supply.
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