I'm a bit out of date on TP stuff, so I hope these aren't silly questions.
Am I right that the buffered SE output from the Legato is basically the same as the Ventus EZ circuit? This in turn seems to be basically the same as the SE-SE version of the 'Wire' amp.
Has anyone tried running custom or high efficiency IEMs off the stock Legato? I'm considering JH-13 pros which are 28ohms and 116dB/mW. It appears that even at unity gain I'd need substantial attenuation to avoid going deaf. Is it possible to safely configure the SE output for less than unity gain - say -20 or -30 dB to avoid having to use excessive digital attenuation? I'll have to double check my numbers, but that's the range I think I end up in.
Am I right that the buffered SE output from the Legato is basically the same as the Ventus EZ circuit? This in turn seems to be basically the same as the SE-SE version of the 'Wire' amp.
Has anyone tried running custom or high efficiency IEMs off the stock Legato? I'm considering JH-13 pros which are 28ohms and 116dB/mW. It appears that even at unity gain I'd need substantial attenuation to avoid going deaf. Is it possible to safely configure the SE output for less than unity gain - say -20 or -30 dB to avoid having to use excessive digital attenuation? I'll have to double check my numbers, but that's the range I think I end up in.
DC on balanced output
I know this problem has been discussed already, sorry for bringing it over again, I read the discussion, but still has not come to a decision what would work best.
I have Beta 22 amp, balanced (but not strictly balanced as I understand), while connecting Legato 3.1 balanced output to Beta my Beta switches off (DC protection module), so it does not work directly connecting.
I tried the following - installing Elna Cerafines electrolytics 100uf 25V in +/- circuit for each balanced output (total 4 caps), then after caps - shortening caps after to the ground with say 10K resistors (I think I should use 100K instead, since Beta load impedance is 47K). That worked so far, but I have doubts about the sound - seems to be a bit thin.
Also, I thought about coupling the GND line in balanced output, while connecting hot and cold lines directly.
Another solution I read about - drop GND output from balanced, which might be dangerous (I think).
Could you advice please what worked the best in terms of the sound? Also, if there are BIII and B22 owners who had the same problem, could you advice too?
SE works out and sounds fantastic!
Thanks!
I know this problem has been discussed already, sorry for bringing it over again, I read the discussion, but still has not come to a decision what would work best.
I have Beta 22 amp, balanced (but not strictly balanced as I understand), while connecting Legato 3.1 balanced output to Beta my Beta switches off (DC protection module), so it does not work directly connecting.
I tried the following - installing Elna Cerafines electrolytics 100uf 25V in +/- circuit for each balanced output (total 4 caps), then after caps - shortening caps after to the ground with say 10K resistors (I think I should use 100K instead, since Beta load impedance is 47K). That worked so far, but I have doubts about the sound - seems to be a bit thin.
Also, I thought about coupling the GND line in balanced output, while connecting hot and cold lines directly.
Another solution I read about - drop GND output from balanced, which might be dangerous (I think).
Could you advice please what worked the best in terms of the sound? Also, if there are BIII and B22 owners who had the same problem, could you advice too?
SE works out and sounds fantastic!
Thanks!
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is there a formula for setting the I/V stage voltage gain? I was not able to find this anywhere. I am hoping to try a lower gain setting as recommended by Russ on another thread. I would like to try something about 0.5-0.75 V output at 0 dBFS. I am currently using the stock R1-R4 and R9-R16 resistors. If I could calculate the value for R1-R4 then I just use 4.4x for R9-R16 as the manuals states, correct?
Fair enough. I am still curious to know how the resistors set the I/V stage gain in Legato though. I am not skilled enough to analyze the circuit to the point where I am as comfortable with it as I would like to be. I have gone through the thread and guide and haven't seen a formula; mind you it would be easy to miss something in the thread. I believe that R9-R11 set the bias current at about 45 mA per QN2 leg. It appears the MOSFET bias voltage is set by a voltage divider of QN2's Vce and the voltage across R6. Any more than that and I need to search through some textbooks... that I don't have access too.
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
Thank you in advance.
Quan
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.
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.
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
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.
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.
What do you consider high input impedance
Is typical 47k input impedance for a preamp consideredhigh?
Is typical 47k input impedance for a preamp consideredhigh?
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