Caps in Aleph 60

Can anyone tell me his opinion for Jamicon electrolytic capacitors (10000MFD 63V). Are they sound good for this project or I have to go for a different and more expensive brand?
Can anyone give me a complete list of all the capacitors (brand name and type) that works well and gives good sound with this project?


Thanks.
 
I think that the most important is the NFB capacitor, C17 in the A60 schematic: here, in my opinion, the maximum quality capacitor is needed.
A nice Elna Cerafine, Starget or Rubycon Black Gate should work well.
I haven't tried swapping in and out so I can't compare these, I had a Starget within my grasp and I used it.

Tortello
 
Ehm... I didn't use it.
In my opinion a low value resistor should be about the same thing.
With for example 4.7Ohm resistor, the maximum voltage between the amp chassis and the ground should be less than one Volt, due to the differential switch, set at 30mA, which is mandatory in Italy.
But this is only my opinion, it'd be better to listen to others, too.
Best regards
Tortello:rolleyes:
 
Nice what you did, but I don't have the experience to say if is good or not.
For sure you gave me a lot of things to read and learn with just one hint.
I 've built many loudspeakers but this is my first amplifier project and I learn a lot while I 'm building this (Is this one of the most important things of DIYres??!)
For sure I don't stick at details , but I use your knowledge and experience to collect the right stuff to built the amplifier for one simple reason... They Cost.

Thanks and sorry about my english

Ioannis
 
Hello Blschuler
looks like the Aleph 0's solution.
In my experience, tantalum capacitors doesn't work well in signal paths, but this is a personal - very subjective - opinion: a good electrolytic is preferable, a direct connection is much more preferable with yet stronger reason :)
With your mods, what is the maximum DC offset, in "warm/cold" conditions?
Thanks
Tortello
 
I have Aleph 30, DC offset moves around 3mV ( warm, of course), otherwise is about 1V after switching on .
Another question. Does anybody tried to change degree of feedback - from 100K to 10k or to 500k or so.How does it affect the sound?
Instead of searching for better caps you can by pass old one with small (1uF I think) polypropylen cap.
 
Thank for your reply, Koy, but I was curious about the DC offset without any DC feedback, as in the Aleph0 or Blschuler design.
In the original A3 design the capacitor makes a DC feedback forcing the DC component to a modest value anyway.
Changing the NFB rate means to modify the amplifier behaviour, and the new situation must be studied, changing accordingly the compensation capacitor.
Also the circuit stability must be verified.
With an Aleph 2/4/5 the disconnection of the jumper between the BAL- and the ground pins are a simple way to verify a +6dB NFB rate change, or -6dB of closed-loop gain.
In my Aleph5 I've tried to reduce the NFB amount, but with no sonic benefit, in my opinion: on the other hand, the PS noise raised accordingly.
As a personal - subjective - point of view, in this point of the circuit I don't like bypassing electrolytic caps with other noblest types, when I tried I obtained a sort of "two gear" sound: not so in power supply applications, for example, where the fastest behaviour might be favourable.
These are my humble opinions, and my experience is not so boundless, I'll be very happy to hear, ehm, to read other experiences, thans to all for this.
Tortello
 
Hi Tortello
DC offset cold: 0.5V
warm: < 10 mV typically but moves around slightly.
The smart thing to do would be to put a potentiometer in parallel with R3 (A4 schematic) like the aleph 0s', I however played mix and max with fixed resistors to obtain low offset.
I left the caps in the amp I just shorted them should I need to change back. DC is low so I don't want to.
As I stated before I like this change. I would be very much interested in hearing testimonials from others who try this simple modification. I have never tried any of the highly praised brands you mentioned.
Some feel the amount of concern over capacitors is disproportional to the actual impact they have on the sound. I hope people try this mod and put some fuel on the fire.;)

Brett
 
This should be the question for Mr. Pass if he will be so kind. How did you deteminate the level of NFB? Why Aleph3 uses 10k and Aleph30 100k resistor?Did you obseved any change in sound? It seems to me when rising the NFB ( powering the value) the midband is a little pronounced. But it seems only to me.My wife did not noticed anything.
Thanks.
 
Hello Koy,

the NFB depends not on the value of the resistor but on the gain that R104 and R102 (Aleph3) define. It´s the same if you use 10k and 1k or 100k and 10k. Both amps have a gain of 10x or 20dB.


Why doesn´t anybody use a DC servo to get over the capacitor problem? It should be very simple to use in the Aleph series. I use one in my main amp where it replaced an 100microfarad MKP type wich replaced a bipolar 110 microfarad cap. The change from capacitor to servo had only positive effects on sound quality. I know some people get very upset when one mentions the word servo but I´ve got only positive experience. I must say though that I always try to minimize the work the servo has to do by matching and tuning for minimum offset without it.

william
 
Your instincts serve you well...
Obi-Wan Kenobi

Koy,
High values of resistance interact with the gate capacitance in a MOSFET. The higher the value, the more sluggishly the capacitance charges and discharges. This tends to limit bandwidth. So it's a balancing act. High Zin (on a Zen?) is a good thing because it doesn't load down the preceding gain stage, but low Zin is good because it gives you wider bandwidth.

Grey