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Old 10th March 2012, 12:48 PM   #491
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There are no shortcuts. You do have access to the internet - why do you need a textbook? Armed with the schematic and a search engine, you can learn all you need to know.
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Old 12th March 2012, 12:34 PM   #492
salavat is offline salavat  Russian Federation
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Seems that nobody has the DC problem on balanced output as I do .

Question - does IVYIII has the same problem as Legato 3.1 with DC on balanced output? I might order IVY stage and use it instead of Legato...
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Old 12th March 2012, 01:15 PM   #493
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Slavat, you could AC couple with output caps on the Legato.

The IVY III sets the output common mode to 0V.
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Old 15th March 2012, 10:51 PM   #494
quan is offline quan  Australia
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Hi Guys , i have been reading thru the thread and understand how to increase the gain of the Legato ie at iv stage if using both bal/Se or at bal/se if using only SE. My knowledge is very limited so pardon me for the question. Is there any formula to work out the gain required. The legato r1-4 is 150 for 1.5V ,to get 2V ie with Buffalo dc -increase to 200r. Max tested by Russ is 364 as per manual with ration 1/4.4 at CCS. I plan to use the legato with dsd 1976 with 4mA p-p. How much gain would that give with 364R? If i need more gain can i increase at bal/se stage in addition with iv stage increase? Would it cause any problem?
Thank you in advance.
Quan
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Old 15th March 2012, 10:57 PM   #495
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Default Drawbacks...

Russ has mentioned many times that the stock configuration of the Legato gain structure was chosen for best performance. So, you can assume that the farther you take the gain from the stock configuration, the more the performance will be compromised.
As a data point, I am running the Legato with the B-II, with 180R up top and 390R on the bottom, and this combo yields about 1.9V out at 0 dB.
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Old 17th March 2012, 04:17 AM   #496
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Quote:
Originally Posted by quan View Post
Hi Guys , i have been reading thru the thread and understand how to increase the gain of the Legato ie at iv stage if using both bal/Se or at bal/se if using only SE. My knowledge is very limited so pardon me for the question. Is there any formula to work out the gain required. The legato r1-4 is 150 for 1.5V ,to get 2V ie with Buffalo dc -increase to 200r. Max tested by Russ is 364 as per manual with ration 1/4.4 at CCS. I plan to use the legato with dsd 1976 with 4mA p-p. How much gain would that give with 364R? If i need more gain can i increase at bal/se stage in addition with iv stage increase? Would it cause any problem?
Thank you in advance.
Quan
You can increase the current to voltage gain, but you will have more output impedance at the balanced outputs. 357-364R will get you close to 2VRMS with little to no compromise (in fact though I did not know it - It actually seems a bit better in terms of THD). The end result will very much depend on what follows. Into a high impedance, excellent, into a low one, not so much.

If you are using single ended output it is much more desirable to increase the gain above that at the BAL/SE stage.

Cheers!
Russ
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Old 17th March 2012, 10:58 AM   #497
quan is offline quan  Australia
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Quote:
Originally Posted by Russ White View Post
You can increase the current to voltage gain, but you will have more output impedance at the balanced outputs. 357-364R will get you close to 2VRMS with little to no compromise (in fact though I did not know it - It actually seems a bit better in terms of THD). The end result will very much depend on what follows. Into a high impedance, excellent, into a low one, not so much.

If you are using single ended output it is much more desirable to increase the gain above that at the BAL/SE stage.

Cheers!
Russ
Thank you Russ, as i am only intending to use SE only. It would be better to increase at BAL/SE. Would 10K be sufficient gain to achieve 2VRMS?
Quan
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Old 22nd September 2012, 08:21 PM   #498
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Default Legato 3.1 Gain Resistor Ratio - please comment on values

Hello

I am using the Legato 3.1 with Buffalo 2.

Looking for highest gain within reason and reading the manual have decided on using 360 ohm for R1 to R4 and 1600 ohm for R9 to R16 - keeping in line with 1/4.4 ratio.

Was also thinking 365 ohm and 1620 ohm in the vishay mbb0207 series (0.4W) as I have these available...

Could you please comment if this will be ok and roughly what gain will be achieved at 0 dbfs?

Also will 1w power rating be best for these resistors (or higher/lower)?

I would experiment but have already destroyed my existing board trying to change these resistors so had to order another so was hoping to make sure before installing.



Would be great to know.

Greetings from UK, Charlie.
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Old 26th September 2012, 04:52 PM   #499
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Default What do you consider high input impedance

Quote:
Originally Posted by Russ White View Post
You can increase the current to voltage gain, but you will have more output impedance at the balanced outputs. 357-364R will get you close to 2VRMS with little to no compromise (in fact though I did not know it - It actually seems a bit better in terms of THD). The end result will very much depend on what follows. Into a high impedance, excellent, into a low one, not so much.

If you are using single ended output it is much more desirable to increase the gain above that at the BAL/SE stage.

Cheers!
Russ
Is typical 47k input impedance for a preamp consideredhigh?
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Old 26th September 2012, 05:36 PM   #500
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Quote:
Originally Posted by pelliott View Post
Is typical 47k input impedance for a preamp consideredhigh?
No. That's fairly typical.
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