Yes, if you going to omit the BAL/SE stage that that will work perfectly well.
Cheers!
Russ
Russ, transformer cores become magnetized by having dc flow in a winding. While it is expected to have DC offset between the output of the buffer and ground (hence use of AC-coupling capacitors), it sounds like there will also be DC between + and - for each channel. It makes sense since there is no feedback and BJT transistors are used but is it safe to hook up transformers between + and - before the AC-coupling capacitors?
Russ/Brian,
There is no mention with regards to Dual Mono wiring with the Legato discrete output stage in your manual for the Legato. Am I to assume that it is the same as the BuffaloII/IVY III dual mono configuration on your Buffalo II webpage? Or do I just order a pair of Buffalo II's and a single order of the Legato and wire it together...
Thanks,
Anand.
There is no mention with regards to Dual Mono wiring with the Legato discrete output stage in your manual for the Legato. Am I to assume that it is the same as the BuffaloII/IVY III dual mono configuration on your Buffalo II webpage? Or do I just order a pair of Buffalo II's and a single order of the Legato and wire it together...
Thanks,
Anand.
Okay Russ, so if I do it like the IVY III (dual mono configuration) will I have to also install the parts for the Ballsie buffer stage on the Legato, so I can use the SE outputs?
Thanks,
Anand.
Hi Russ
I've had a preliminary listen to Legato. Both I/V stages powered by a single BP 12 -0 -12V Placid, Bal to SE converter powered by a prexisting 15- 0- -15V supply. I omitted the buffer amps. I substituted ZTX651 for BC550, as it's given me good results in similar applications.
BTW I find the total current drawn, per rail, is only 180mA- i.e. 90 mA per channel.
It's excellent sounding, much better than IVY III. I think that what's you've been expecting to hear- despite your and Brian's reticence when it comes to subjective opinion!
- so I thought I'd put you out of your misery But, in fact, I've not not used IVY III for some time, so it will interesting to see what other people think. I've been using an alternative discrete I/V circuit, which also IMHO betters IVY III sonically. So for me, it's more a question of whether this bests Legato. But that's a discussion for another time!
Thanks
Paul
I've had a preliminary listen to Legato. Both I/V stages powered by a single BP 12 -0 -12V Placid, Bal to SE converter powered by a prexisting 15- 0- -15V supply. I omitted the buffer amps. I substituted ZTX651 for BC550, as it's given me good results in similar applications.
BTW I find the total current drawn, per rail, is only 180mA- i.e. 90 mA per channel.
It's excellent sounding, much better than IVY III. I think that what's you've been expecting to hear- despite your and Brian's reticence when it comes to subjective opinion!
- so I thought I'd put you out of your misery But, in fact, I've not not used IVY III for some time, so it will interesting to see what other people think. I've been using an alternative discrete I/V circuit, which also IMHO betters IVY III sonically. So for me, it's more a question of whether this bests Legato. But that's a discussion for another time!Thanks
Paul
And I take it that the buffer section (QN7-QN14, R25-R28) needs to be included in my build of the dual Buffalo/dual Legatos since I'm essentially getting my balanced outputs from the normally labelled SE outputs (which are in series with the integrated Ballsie lite converter stage)? I don't believe my preamp's input impedance (even at the lowest volume setting) is as low as 4K, it's much more than that...at least 10K.
Anand.
No you won't need the buffer, because the output will be from the BAL/SE section. But you don't need to worry over it, it won't hurt anything to have it.
The buffer on the Legato only applies to the balanced output prior to the BAL/SE stage. Refer to the schematic.
Cheers!
Russ
Hi Russ
Well it's run in a bit more now. As the current drawn without the buffers is about halved, I've refitted the Paul Hynes S17LN/S37LN regs- one pair for each stage (left right I/V, Bal to SE) that I used for IVY III. For convenience I left these set to 15/0/-15V. For the sake of argument, let’s say I did this just to make comparisons with IVY III more valid -I don't want to put my foot in again
It sounds absolutely superb! Stunningly good! Unbelievably good! I don't say this lightly- it sounds better than the I/V stage I was using (which used a CFT, with a CCS above and below), and I've recently invested a lot of time and effort in that. Believe me it was no slouch sound-wise either- Legato had to be damn good to get my attention!
Did you try many different devices in the CFP before settling on the BS250/BC550B combo? I used a ZTX651 in place of the BC550 as this seemed to give better sound in the circuit I mentioned, but, if anything, it has slightly lower hfe. Was the circuit unstable with higher hfe BJTs? If not, I expect a 2SC2547E or 2SC2240 in place of the BC550B might be even better- higher hfe and very linear too
BTW shouldn't R20,21,23,24 ideally be higher wattage types- though of similarly high quality? I like to overrate resistor power rating by a minimum of 2x, and preferably 3x, for long term stability. Even at with a 12V supply they're dissipating 0.67W; at 15V 0.83W!
But whatever, the bottom line is Legato is awesome- many thanks, and well done!
Paul
Sorry, I have to say it- IMO Legato sounded excellent with a single BP Placid, but even better with the PH regs (though of course the increased supply voltage may be relevant here). I take your point that the current drawn is pretty constant, but the circuit still looks pretty susceptible to PS quality to me. I guess we may just have to agree to differ about this
Well it's run in a bit more now. As the current drawn without the buffers is about halved, I've refitted the Paul Hynes S17LN/S37LN regs- one pair for each stage (left right I/V, Bal to SE) that I used for IVY III. For convenience I left these set to 15/0/-15V. For the sake of argument, let’s say I did this just to make comparisons with IVY III more valid -I don't want to put my foot in again
It sounds absolutely superb! Stunningly good! Unbelievably good! I don't say this lightly- it sounds better than the I/V stage I was using (which used a CFT, with a CCS above and below), and I've recently invested a lot of time and effort in that. Believe me it was no slouch sound-wise either- Legato had to be damn good to get my attention!
Did you try many different devices in the CFP before settling on the BS250/BC550B combo? I used a ZTX651 in place of the BC550 as this seemed to give better sound in the circuit I mentioned, but, if anything, it has slightly lower hfe. Was the circuit unstable with higher hfe BJTs? If not, I expect a 2SC2547E or 2SC2240 in place of the BC550B might be even better- higher hfe and very linear too
BTW shouldn't R20,21,23,24 ideally be higher wattage types- though of similarly high quality? I like to overrate resistor power rating by a minimum of 2x, and preferably 3x, for long term stability. Even at with a 12V supply they're dissipating 0.67W; at 15V 0.83W!
But whatever, the bottom line is Legato is awesome- many thanks, and well done!
Paul
Sorry, I have to say it- IMO Legato sounded excellent with a single BP Placid, but even better with the PH regs (though of course the increased supply voltage may be relevant here). I take your point that the current drawn is pretty constant, but the circuit still looks pretty susceptible to PS quality to me. I guess we may just have to agree to differ about this
Hi Paul,
Try the PlacidBP with 20-ohm pots for the CCS. I think You will be pleased. You can easily run that at 15V. I am quite certain that is the bulk of the difference you are hearing.
As for the resistors, the 1W rating is quite adequate, and going for higher power rating rating would more than likely make things worse not better. Still feel free to do it if you like.
As for the transistors. I Spent months testing combinations. I simply found the parts we selected in the end to provide the best overall consistently excellent results. That said, there are lots of combinations that will work very well. The circuit should be stable even with high HFE transistor.
I am very glad you are enjoying it. I feel much the same as you. I have a hard time describing to folks how it sounds. But it is very groovy.
The key feature of the circuit is it's symmetrical nature, which nicely boosts differential PSRR to very high levels. Any ripple that does make it out will be tiny, and common mode. Balanced gear nicely nullifies that.
Cheers!
Russ
Try the PlacidBP with 20-ohm pots for the CCS. I think You will be pleased. You can easily run that at 15V. I am quite certain that is the bulk of the difference you are hearing.
As for the resistors, the 1W rating is quite adequate, and going for higher power rating rating would more than likely make things worse not better. Still feel free to do it if you like.
As for the transistors. I Spent months testing combinations. I simply found the parts we selected in the end to provide the best overall consistently excellent results. That said, there are lots of combinations that will work very well. The circuit should be stable even with high HFE transistor.
I am very glad you are enjoying it.
I feel much the same as you. I have a hard time describing to folks how it sounds. But it is very groovy. The key feature of the circuit is it's symmetrical nature, which nicely boosts differential PSRR to very high levels. Any ripple that does make it out will be tiny, and common mode. Balanced gear nicely nullifies that.
Cheers!
Russ
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Hi Russ
"As for the resistors, the 1W rating is quite adequate, and going for higher power rating rating would more than likely make things worse not better."
Don't begin to understand that I'm afraid. Why not use two 680R CCF60 1W resistors in parallel?
"As for the transistors. I Spent months testing combinations. I simply found the parts we selected in the end to provide the best overall consistently excellent results. That said, there are lots of combinations that will work very well. The circuit should be stable even with high HFE transistor."
By testing, do you mean listening, or measurement, or both? What criteria did you use in your preliminary selection? Any details you feel able to provide would be fascinating!
Thanks again
Paul
"As for the resistors, the 1W rating is quite adequate, and going for higher power rating rating would more than likely make things worse not better."
Don't begin to understand that I'm afraid. Why not use two 680R CCF60 1W resistors in parallel?
"As for the transistors. I Spent months testing combinations. I simply found the parts we selected in the end to provide the best overall consistently excellent results. That said, there are lots of combinations that will work very well. The circuit should be stable even with high HFE transistor."
By testing, do you mean listening, or measurement, or both? What criteria did you use in your preliminary selection? Any details you feel able to provide would be fascinating!
Thanks again
Paul
Hi Paul.
I understand what you are saying, but I am going by what the manufacturer tells me is acceptable for long term reliability. As I said they are well within their rating. This is something I was very careful about.
Still you could quite easily use two 680R as you might like to. In fact since you are not using the buffer it would be quite simple on the current board. Just install the 680 resistors in R25-R28 as well as R20,R21 and R23,R24 and a couple jumpers to join them (I am sure you can figure it out by looking at the board). Its up to you.
I may add additional resistors in parallel to a later revision, but I assure you things will be just fine as they are. Please, don't worry over it, just enjoy the music.
I did both listen and measure as always.
I understand what you are saying, but I am going by what the manufacturer tells me is acceptable for long term reliability. As I said they are well within their rating. This is something I was very careful about.
Still you could quite easily use two 680R as you might like to. In fact since you are not using the buffer it would be quite simple on the current board. Just install the 680 resistors in R25-R28 as well as R20,R21 and R23,R24 and a couple jumpers to join them (I am sure you can figure it out by looking at the board). Its up to you.
I may add additional resistors in parallel to a later revision, but I assure you things will be just fine as they are. Please, don't worry over it, just enjoy the music.
I did both listen and measure as always.
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