My_Ref Fremen Edition VS My_Evo Rev A
I've had the chance to compare the amp with a My_Evo Rev A.
I was expecting a BIG difference but it was not the case...
The My_Evo under test sounds more refined and natural but bass is too much controlled, to the point it could be defined 'bass shy' with an impact also on dynamic.
I'm going to help my friend to mod it to fix that bass problem (I think that Caddocks in place of Mills in R7 he used will do the trick), let's see how they compare after...
Anyway the My_Evo is a better amp but the good news is that the FE is pretty near.
Take in account that a Blackgate in C9 is needed to achieve that level of performance, the My_Evo uses a DC-Servo...
I've had the chance to compare the amp with a My_Evo Rev A.
I was expecting a BIG difference but it was not the case...
The My_Evo under test sounds more refined and natural but bass is too much controlled, to the point it could be defined 'bass shy' with an impact also on dynamic.
I'm going to help my friend to mod it to fix that bass problem (I think that Caddocks in place of Mills in R7 he used will do the trick), let's see how they compare after...
Anyway the My_Evo is a better amp but the good news is that the FE is pretty near.
Take in account that a Blackgate in C9 is needed to achieve that level of performance, the My_Evo uses a DC-Servo...
The filters built into the amplifiers should be equal to allow that Bass inequality judgment.
If the filters are different, then one can never know what or which is causing the Bass difference. It's a case of change ONE item at a time to hear the difference else no valid conclusions can be drawn on what is causing the change.
An example of a flawed but hypothetical conclusion:
"I have compared two similar amplifiers. There are 172 minor component value or minor topology differences between the two amplifiers. I notice that one uses a particular pair of capacitors that are cheap and industrial and reputedly quite competent and most importantly meet specification.
The other amplifier uses two exotic "audio" capacitors in those same two locations.
I can clearly hear a difference in the way Bass is reproduced between those two amplifiers.
I conclude that those capacitors must be responsible for the difference. In future I will specify the same two exotic capacitors for those two locations in amplifiers, because I have heard the difference."
That is hypothetical conclusion complete codswallop.
If the filters are different, then one can never know what or which is causing the Bass difference. It's a case of change ONE item at a time to hear the difference else no valid conclusions can be drawn on what is causing the change.
An example of a flawed but hypothetical conclusion:
"I have compared two similar amplifiers. There are 172 minor component value or minor topology differences between the two amplifiers. I notice that one uses a particular pair of capacitors that are cheap and industrial and reputedly quite competent and most importantly meet specification.
The other amplifier uses two exotic "audio" capacitors in those same two locations.
I can clearly hear a difference in the way Bass is reproduced between those two amplifiers.
I conclude that those capacitors must be responsible for the difference. In future I will specify the same two exotic capacitors for those two locations in amplifiers, because I have heard the difference."
That is hypothetical conclusion complete codswallop.
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Sure, LM318 compensation is different for sure (there are one cap and one resistor less...).
Though I think that a different output resistor (R7 in the Rev_C) could make a difference like it did on the Rev C.
I do agree, an application where they seem unbeatable is in CCSs, for the 50R resistor they seems the best ones I've tried so far...
A lot of people uses them also in XOs, at least here in Italy.
Try a capacitor on the adjustment pin
The LM317 and LM337 datasheets say that a capacitor on the adjustment pin
can reduce the ripple. It looks like that is what is happening here. Try another
simulation by combining the two 25R into one 50R and then tie your capacitors
to group and redo the simulation. Take care.
The LM317 and LM337 datasheets say that a capacitor on the adjustment pin
can reduce the ripple. It looks like that is what is happening here. Try another
simulation by combining the two 25R into one 50R and then tie your capacitors
to group and redo the simulation. Take care.
I hope some of you could give your opinions on what resistors and other components I should buy for my situation.
My FE amp will be powering my BLH cabinets with Fostex FE206E drivers. They are in the corners of my room yet they only play down to about 55Hz. The specs claim they will go to 20KHz but I have old man ears from years as a machinist. I can probably not hear anything higher than 14KHz . Since these are single drivers with a whizzer cone I guess they can not match the detail of a cabinet with a seperate tweeter. A graph of their response curve would probably show a upper mid range "shout" and a bit of a upper mid bass dip. The graph would also be "spikey".
For these reasons I think PRP resistors would not be a good match. I've heard the Takman are smooth and laid-back (romantic) while PRP are clean and accurate but maybe sharp. How does a Caddock compare to these ? Are Susumu and Vishay sharp or smooth ?
Thanks in Advance for any advice.
Joe in Alabama
My FE amp will be powering my BLH cabinets with Fostex FE206E drivers. They are in the corners of my room yet they only play down to about 55Hz. The specs claim they will go to 20KHz but I have old man ears from years as a machinist. I can probably not hear anything higher than 14KHz . Since these are single drivers with a whizzer cone I guess they can not match the detail of a cabinet with a seperate tweeter. A graph of their response curve would probably show a upper mid range "shout" and a bit of a upper mid bass dip. The graph would also be "spikey".
For these reasons I think PRP resistors would not be a good match. I've heard the Takman are smooth and laid-back (romantic) while PRP are clean and accurate but maybe sharp. How does a Caddock compare to these ? Are Susumu and Vishay sharp or smooth ?
Thanks in Advance for any advice.
Joe in Alabama
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Stick with commercial grade 1% 50ppm metal film resistors.
Adjust the RF filter time constant to adjust the treble output.
Only when you have tried that and failed to get what you want, come back and ask again what could be changed for a smoother sound to replace whatever it is that is not to your liking.
Adjust the RF filter time constant to adjust the treble output.
Only when you have tried that and failed to get what you want, come back and ask again what could be changed for a smoother sound to replace whatever it is that is not to your liking.
An all Takmans config is not advisable, IMHO, too much colored... PRPs are not harsh but balanced and full bodied.
Full bodied,a bit closed and confused (MK132) not to be used in direct signal path or feedback, IMHO.
MP9x0 fares very well in CCSs or as output resistors.
I would use the word transparent.
Components selection
Testing will continue but so far the best combination for signal path I've found is:
R7 12K Metal film (PRP 9372)
R10 390R Carbon film (Takman Rex, Riken)
R12 3K3 Metal film (TX 2575 or PRP 9372)
R13 100K Carbon film (Takman Rex, Riken)
For R12 a naked z-foil seems the best but a much (much) cheaper PRP is also very good (marking direction is the same as signal
[*]).
For carbon films Takmans sound very good, full and balanced (red band toward ground
[*]), Rikens sound even fuller, maybe too much.
For R101/R201 (current setting resistors) the fuller and best ones are Caddocks MP915.
For R104/R204 I'm using PRPs (marking direction is opposite to ground
[*]).
[*] Only if you trust in resistors directionality (or in my opinion...), otherwise ignore it.
Testing will continue but so far the best combination for signal path I've found is:
R7 12K Metal film (PRP 9372)
R10 390R Carbon film (Takman Rex, Riken)
R12 3K3 Metal film (TX 2575 or PRP 9372)
R13 100K Carbon film (Takman Rex, Riken)
For R12 a naked z-foil seems the best but a much (much) cheaper PRP is also very good (marking direction is the same as signal
[*]).
For carbon films Takmans sound very good, full and balanced (red band toward ground
[*]), Rikens sound even fuller, maybe too much.
For R101/R201 (current setting resistors) the fuller and best ones are Caddocks MP915.
For R104/R204 I'm using PRPs (marking direction is opposite to ground
[*]).
[*] Only if you trust in resistors directionality (or in my opinion...
), otherwise ignore it.
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Yee Hee !
The full basic BOM arrived from Mouser yesterday. I'm going to build it "vanilla" first so hopefully I'll be able to hear the improvements step-by step. I'm using sockets at all the resistor spots per your recommendations, so the upgrade path should be a bit more convenient.
Back in a few days.......darn, have to take out storm windows - put in screens, rake yard, eliminate large pile of dirty clothes, pay bills and talk to my family. Oh - the distractions!!!
The full basic BOM arrived from Mouser yesterday. I'm going to build it "vanilla" first so hopefully I'll be able to hear the improvements step-by step. I'm using sockets at all the resistor spots per your recommendations, so the upgrade path should be a bit more convenient.
Back in a few days.......darn, have to take out storm windows - put in screens, rake yard, eliminate large pile of dirty clothes, pay bills and talk to my family. Oh - the distractions!!!
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Fine
I've attached two pictures that will make more evident which resistors's direction to use for who cares about it.
Attachments
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Back in a few days.......darn, have to take out storm windows - put in screens, rake yard, eliminate large pile of dirty clothes, pay bills and talk to my family. Oh - the distractions!!!
Yea, me too. My case construction was slowed when my wife loaned my table saw to one of her friends. Then she decided we needed new wood floors in the kitchen, dining room and bath. Then I had my off days filled with doctor appointments.
Life is what happens while we're busy making plans.
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