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Legato 3 - Look ma! No caps!

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#646
Removing IC2/IC3 output buffers

I'm using the SE outputs to drive my amp (Pass F5Tv2). I don't plan on driving headphones so I'd like to remove the IC2/3 output buffers. Do I need to make any other changes or just desolder, trim DC offset and go?
 
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#647
After some digging I found the post that says to add jumpers J5/J6 as well after removing the opamps. I figured i had to connect the signal thru somewhere, just didn't know where. I desoldered the legs off the opamps and lifted them off the pads, but the case is soldered down or something so i left it on the board.

I think the sound is much better now. There's more detail, better sound stage and quite a bit less forward in the midrange. I can turn it up pretty loud without feeling any fatigue. Seems like there's a bit more bass but it's very tight and not boomy.

I wasn't entirely in love with the DAC until I removed the opamps, but I'm really happy now. Definitely recommend running without the buffer if you aren't driving headphones!
 
#648
abkingsbury said:
After some digging I found the post that says to add jumpers J5/J6 as well after removing the opamps. I figured i had to connect the signal thru somewhere, just didn't know where. I desoldered the legs off the opamps and lifted them off the pads, but the case is soldered down or something so i left it on the board.

I think the sound is much better now. There's more detail, better sound stage and quite a bit less forward in the midrange. I can turn it up pretty loud without feeling any fatigue. Seems like there's a bit more bass but it's very tight and not boomy.

I wasn't entirely in love with the DAC until I removed the opamps, but I'm really happy now. Definitely recommend running without the buffer if you aren't driving headphones!
Click to expand...

Just to clarify a couple things...

J5/J6 are used to route the SE output of the op-amp to the SE-output pins when the buffers are not installed. They will have no impact if you are not using the SE outputs.

The parts you removed are not op-amps. They are buffers (actually a push-pull output stage).

When using the balanced outputs, the bal->se stage will have no impact on the sound, especially if you omit the op-amp.

Also, details of which components to omit when the bal->se stage is not needed are listed in the user Legato manual: http://www.twistedpearaudio.com/docs/linestages/legato_user_manual_3.1.0.pdf

I am glad you are enjoying the sound. 🙂
 
#649
I've used Legato v2 with supertex parts and more recently IVY-III. Thinking about trying Legato v3.1. Any reason the HP out couldn't/shouldn't be used to drive a powered sub for a 2.1 setup? E.g., Rythmik servo A370PEQ via L/R RCA line-in and longish interconnects.

BK
 
#651
abkingsbury said:
I wasn't entirely in love with the DAC until I removed the opamps, but I'm really happy now. Definitely recommend running without the buffer if you aren't driving headphones!
Click to expand...
Thanks for suggestion! After reading your post i finally decided to try it and lifted in/out legs of the buffers and installed jumpers quickly to see if i like it. We did a quick listening test with a friend before and after the modification. The immediate difference is that sound is less forward and highs are less "sizzling" while both - a bit cleaner and more detailed, mainly at higher frequencies. Before the mod - a friend often found highs of my Buffalo a bit too pronounced and slightly less natural compared to his multibit DAC, and now even he was happy while admitting that Buffalo resolution and transparency is unmatched. 🙂
I worried a bit that removing buffers could make sound "soft" or less dynamic, but it's definitely not the case.
I guess this simple "mod" is the #1 answer for those who find sound of buffalo/legato a bit bright/forward (if not using headphones). The effect is bigger than swaping opamps or caps i think
 
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#652
I can't say I personally agree with that assessment at all - I find the buffered output better in all regards - and definitely more flexible in terms of load capability. It offloads the job of driving current from the opamp and lets it focus on its main task - converting the balanced signal to single ended and controlling things via feedback. 🙂 Still - experimenting is the fun of DIY - do as you like.
 
#653
Maybe i was too quick with conclusions. After some longer listening i found that it actually sounds brighter and "thinner" without buffers. A bit more relaxed which helps to pleasantly "smooth" things out at first, but in the long run - there is less lows/mids now and a bit less definition and dynamics, with bass suffering the most. Could be opamp dependent (i use "metal can" LME49720HA)
P.S. I feel it's better to mess with opamps than buffers. For less forward midrange, deeper soundstage and larger bass - one can try LME49860 for example...
 
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#654
bk856er said:
I've used Legato v2 with supertex parts and more recently IVY-III. Thinking about trying Legato v3.1. Any reason the HP out couldn't/shouldn't be used to drive a powered sub for a 2.1 setup? E.g., Rythmik servo A370PEQ via L/R RCA line-in and longish interconnects.

BK
Click to expand...

Making really beautiful music! My favorite BII combination so far. It has a bit of magic/soul/pixie dust. Great job, guys.

BK
 
#659
The Legato has been out of stock for a while now I think -- will it return to stock or be discontinued? Planning my build and still very much interested in this transistor-based I/V approach (though the error amp on the Mercury has a real pull on me too!)
 
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