SMT 2520 vs Standard Size Component 2520

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Siegfried Meier

Siegfried Meier

Well-known member
Joined
Jul 2, 2004
Messages
1,606
Location
Ontario, Canada
Hey guys,

So I just built up a pair of the GAR2520's but decided to compare them to my older SMT 2520's made by Burdij.

Here's what I did:

1. Recorded a DI guitar track into Pro Tools, clean with Avalon U5.
2. Reamped that signal through a JD7 into a Rickenbacker TR75 amp.
3. Recorded a pass of clean guitar through an API 312 clone with the SMT installed installed (mic was Peluso R14, direct into preamp, no snake)
4. Recorded a pass of dirty guitar by inserting a DS-1 pedal - still with SMT 2520 installed
5. Did 3 and 4 again with the GAR2520 installed

When I had them all in Pro Tools, I listened back and forth and had a hard time hearing any difference, so I decided to flip one out of phase and sum the 2 dirty's together, and the 2 cleans together.  I was quite surprised when I discovered that they nearly cancelled out.  There was clearly some lower level stuff present as these are analog passes, as well as multiple passes through an amp that sounds a bit different each time.  But I truly thought that I would be able to hear a much bigger difference.

What exactly is the difference, sonically, in opamps, that I should be hearing?  And, of course, perhaps both of these circuits are just very well made, and SMT components are not nearly as bad as we've been told they are?

Food for thought.
Thanks!
Sig
 
Yeah, it is one of those things that usually only show up after many tracks are recorded if both op amps are quality.  It is how the tracks sit together naturally in the mix.  Subtle!

EDIT:  I can usually hear it on transits the best.  Try recording a tambourine and see what you like.  Or if you are summing with a folcrom or something try it in those spots.  Pretty big difference can be heard in on the mix info.
 
I haven't heard the Burdij op amps but i am a huge fan of Scott Liebers op amps.  Specially the Red Dot.  I have done many comparisons and it wins all the time to my ears and others.  The Gar is close!
 
Andy i tought you breadboarded yours??
Gustav has boards done for this?
Whats your impressions? i think you really like PP Doas??
Thanks
 
Hi,


  ??? breadboard??? not really my forte!!!


  the wonderful Audiox did a layout at about the same time as the Studer 169-500 eq. You get two OA10 boards with each eq pcb. I can thoroughly recommend them. They are very smooth, warm and full. Less Midrange Clack than any 2520 I have. I have several different originals, and some Fabio boards too. The real joy comes with gains over 20db, when the slewrate goes up to 50v/usec from 5v/usec, uncompensated. Rreally, really nice.


    I have been swapping 'em out for 2520's for a little while now. I mostly prefer the OA10, but have kept some 2520 so I can have a choice.



        Just my pennies worth, and I am sure that someone will disagree!



      ANdyP
 
A DOA made with SMT is still discrete.  :eek:
I don't think there are inherent quality problems with SMT. My only beef is they're a bitch to solder.  :)
 
kato said:
A DOA made with SMT is still discrete.   :eek:
I don't think there are inherent quality problems with SMT. My only beef is they're a bitch to solder.   :)
Click to expand...

Yes, indeed you are correct, that was just my way of explaining it!  However, I had always heard that SMT components weren't as audiophile grade as standard sized components.  And I've never soldered them, I don't think I'd ever really bother even if I had to.
 
My DOA's are all PH type, but I've designed the SMT version too, because I've the intention to make all DOA's on SMT even if some components will be PH type yet.
I these months I've seen the differences between SMT  and PH components.
Regarding caps there are very little differences but I prefer the SMT components.
The differences are on the resistors,  the PH res were superior in performances vs. SMT types, but nowdays there are very high performaces SMT resistors. There are two types of SMT res: thick film and thin film.
The most common SMT res type is the thick film, and this is the much lower performing type vs PH res. thin film are similar in quality to PH type, but thin film SMT resistors cost much more respect thick film SMT res and they cost usually more the equivalent PH type.

I have done listening and electrical tests using some SMT APP2050 and some PH APP2050 and they are pratically equal between them.

 
Siegfried Meier said:
Hey guys,

So I just built up a pair of the GAR2520's but decided to compare them to my older SMT 2520's made by Burdij.

Here's what I did:

1. Recorded a DI guitar track into Pro Tools, clean with Avalon U5.
2. Reamped that signal through a JD7 into a Rickenbacker TR75 amp.
3. Recorded a pass of clean guitar through an API 312 clone with the SMT installed installed (mic was Peluso R14, direct into preamp, no snake)
4. Recorded a pass of dirty guitar by inserting a DS-1 pedal - still with SMT 2520 installed
5. Did 3 and 4 again with the GAR2520 installed

When I had them all in Pro Tools, I listened back and forth and had a hard time hearing any difference, so I decided to flip one out of phase and sum the 2 dirty's together, and the 2 cleans together.  I was quite surprised when I discovered that they nearly cancelled out.  There was clearly some lower level stuff present as these are analog passes, as well as multiple passes through an amp that sounds a bit different each time.  But I truly thought that I would be able to hear a much bigger difference.

What exactly is the difference, sonically, in opamps, that I should be hearing?  And, of course, perhaps both of these circuits are just very well made, and SMT components are not nearly as bad as we've been told they are?

Food for thought.
Thanks!
Sig
Click to expand...

Who said SMT parts are bad..? In many cases they are the same guts just with less plastic and shorter leads.

re: the differences in a null test, you can trim gain, so audible differences will be from frequency response, phase shift, and noise floor.

You feedback network values, tolerance, and to some extent layout parasitics could have more influence than the opamps if they are well executed with plenty of loop gain margin.

JR
 
Transients may expose the headroom room issues
one of the places you may find them different ,
and one would think there would be more thermal noise penalties
try cranking them and measuring noise as well [ as pushing them ]

smd  ?
can't see it  , can't solder it , can't stand it
 
strangeandbouncy said:
   the wonderful Audiox did a layout at about the same time as the Studer 169-500 eq. You get two OA10 boards with each eq pcb. I can thoroughly recommend them. They are very smooth, warm and full. Less Midrange Clack than any 2520 I have. I have several different originals, and some Fabio boards too. The real joy comes with gains over 20db, when the slewrate goes up to 50v/usec from 5v/usec, uncompensated. Rreally, really nice.


     I have been swapping 'em out for 2520's for a little while now. I mostly prefer the OA10, but have kept some 2520 so I can have a choice.



        Just my pennies worth, and I am sure that someone will disagree!



       ANdyP
Click to expand...

Just emailed Gustav earlier on today, he is cool about selling just the DOAs PCBs. Just letting you guys know...
 

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