Legato Tweakers Thread...

[RichLund]

Received my Legato today, very nice.

Before I start can I ask what the components marked with an 'X' are: R25 - R28, QN7 - QN14. Are these the output buffer?

Should I omit the buffer if using with DCB1 preamp?

Thanks

 

[Russ White]

Received my Legato today, very nice.

Before I start can I ask what the components marked with an 'X' are: R25 - R28, QN7 - QN14. Are these the output buffer?

Thanks

Hi Rich,

Thanks for the kind words.

Did you check out the manual yet?

I think you will find the answer there.

If your amp has an input impedance > 5K or so, then I would omit the buffer. But it is completely up to you.

Cheers!
Russ

 

[jrenkin]

Can you use two Legatos to run dual mono with two BII?

 

[Russ White]

Can you use two Legatos to run dual mono with two BII?

Yes you can. You can also use 2 Buffalo II with one Legato. Both approaches yield excellent results.

 

[RichLund]

Ahh Russ, my face is lodged firmly in my palm... doh!

As usual superb quality kit from you boys. I will be using SE and will also try some of the mods recommended in the thread.

I shall check the specs of the rest of my kit.

Many thanks for the speedy reply.

 

[Russ White]

Ahh Russ, my face is lodged firmly in my palm... doh!

As usual superb quality kit from you boys. I will be using SE and will also try some of the mods recommended in the thread.

I shall check the specs of the rest of my kit.

Many thanks for the speedy reply.

If you are only using the SE output it is already buffered so you can very safely omit the balanced output buffer, and I would recommend that.

Cheers!
Russ

 

[jrenkin]

Yes you can. You can also use 2 Buffalo II with one Legato. Both approaches yield excellent results.

Excellent, thanks! So one Legato will do, but dual mono requires two Ivy III (per the website)? Of course I have one Buff II and one Legato and one Ivy III, so I have to get my system combobulated.

Unrelated trivia: the IV lock device (as in intravenous), was developed at the University of Colorado in Boulder (the Buffs, for the football team, the Buffalos) and so in Colorado only, this device is called a "Buff cap", or Buffalo cap. At least they have not yet come out with the Buffalo II cap. I am already getting confused....

 

[Narla]

It is possible to run without caps that way as long as the SE offset is low enough. This will not always be the case. If your measured SE offset is low then you are fine. You will just need to check that carefully. If you like you can even trim out the offset using a parallel trim resistor on the CCS for the side that you want to adjust downward.

If you only use SE output you can definitely use lower value film caps. Say 2.2-4.7uf. Then you will be completely safe and no worries about offset in the least.

Russ - I plan to run the Legato SE into a Nelson Pass B1 Buffered passive preamp that has 1uf input caps. Does this mean I can safely omit the C5-C8 100uf output caps?

 

[merlin el mago]

Received today my Legato, thanks to sharing your experiences, wich value output film cap the next stage have an input impedance of 1 Meg with 10K shunt attenuator?

 

[Russ White]

Russ - I plan to run the Legato SE into a Nelson Pass B1 Buffered passive preamp that has 1uf input caps. Does this mean I can safely omit the C5-C8 100uf output caps?

Yes you should be ok if you do that. What little offset is left should be dealt with by the AC coupled B1.

Cheers!
Russ

 

[Russ White]

Received today my Legato, thanks to sharing your experiences, wich value output film cap the next stage have an input impedance of 1 Meg with 10K shunt attenuator?

I assume then the actual input impedance is 10K?

If so than I would choose something around 4.7-10uf. But even down to 2.2uf should be ok.

Cheers!
Russ

 

[Russ White]

Excellent, thanks! So one Legato will do, but dual mono requires two Ivy III (per the website)?

You can do the same thing with one IVY-III, but you would want to change some resistor values. Personally I would just use two.

 

[merlin el mago]

I assume then the actual input impedance is 10K?

If so than I would choose something around 4.7-10uf. But even down to 2.2uf should be ok.

Cheers!
Russ

Not really because the attenuator is shunt type not ladder so is changing the input impedance in each step.

Thanks
Felipe

 

[Russ White]

Well I would need to know the minimum and the maximum impedance to give you a good answer. If the minimum is 10K then my advice still applies.

 

[Theodosis O.]

Hi,

Which is the BEST opamp for the bal/se convertion ?

Do you believe OPA627 will be better than the stock opamp (LME49720) ?

 

[merlin el mago]

Well I would need to know the minimum and the maximum impedance to give you a good answer. If the minimum is 10K then my advice still applies.

Yes the shunt attenuator minimum impedance is 10K, thank you

 

[Russ White]

Hi,

Which is the BEST opamp for the bal/se convertion ?

Do you believe OPA627 will be better than the stock opamp (LME49720) ?

No, because it is a single, and you need a dual.

Honestly there are several really good unity gain stable dual op amps that would work very well.

 

[pelliott]

Higher output on Lagato

I apologize for this question but I am confused about getting 2v out put.
The manuals state just change the 150ohm 1 watt to 187ohm but on some of these threads changing another 1watt as well. which one?

 

[barrows]

pell...

You need to change both R1-4 and R20,21,23,24 to change the gain. I believe Russ notes the ideal ratio between the upper resistors and lower is 2.2.
I got 1.9 volt output with the following combination:
R1-4: 180R
R20,21,23,24: 390R

 

[Theodosis O.]

No, because it is a single, and you need a dual.

Honestly there are several really good unity gain stable dual op amps that would work very well.

Thanks Russ,

There are adaptors like this:
Dual to Mono Op amp OPA627BP OPA627 replace NE5532 - eBay (item 350409857543 end time Dec-01-10 23:54:36 PST)

Since I use the SE output in dual mono 2 Legato, my question is if there will be any improvment by changing the opamp by a better one.

Thanks again