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Old 15th March 2012, 02:00 AM   #71
jERiCOh is offline jERiCOh  Canada
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I'm getting 79nV Pk-Pk that way... It is great but I like the fact that I get 32nV Pk-Pk the other way. And about my half sinewave... I was wrong, it is more like taking the sawtooth and rounding them until they are almost gone.
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Old 15th March 2012, 06:00 AM   #72
soongsc is offline soongsc  Taiwan
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That is the basic function of the low pass filter. Lower the cut off frequency, the less ripple you get. However, it's still important to look at the dynamic interaction between the amplifier and the power supply. Almost impossible to do in SPICE unless you have the right models.
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Old 15th March 2012, 05:12 PM   #73
squalor is offline squalor  United States
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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

Last edited by squalor; 15th March 2012 at 05:16 PM.
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Old 15th March 2012, 06:12 PM   #74
AndrewT is offline AndrewT  Scotland
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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.
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Old 15th March 2012, 07:31 PM   #75
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Quote:
Originally Posted by squalor View Post
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.
An all Takmans config is not advisable, IMHO, too much colored... PRPs are not harsh but balanced and full bodied.

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How does a Caddock compare to these ?
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.

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Are Susumu and Vishay sharp or smooth ?
I would use the word transparent.
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Old 17th March 2012, 09:54 PM   #76
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Default 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.
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Old 18th March 2012, 12:31 AM   #77
bcmbob is offline bcmbob  United States
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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!!!
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Old 18th March 2012, 01:14 AM   #78
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Quote:
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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.
Fine

I've attached two pictures that will make more evident which resistors's direction to use for who cares about it.
Attached Images
File Type: jpg IMG192.jpg (320.7 KB, 384 views)
File Type: jpg IMG193.jpg (297.7 KB, 279 views)
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Old 18th March 2012, 05:58 PM   #79
squalor is offline squalor  United States
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Is this the right kind of flux for SMD ?

83-1097-2331 Kester Solder, Fluxes & Accessories
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Old 18th March 2012, 06:06 PM   #80
squalor is offline squalor  United States
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Quote:
Originally Posted by bcmbob View Post

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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