This topic has encouraged me to add the Cree diodes to my already quite modified Crack (speedball, choke, output and last power supply film capacitors). I wasn't expecting as much improvement as it turned out to be. Still having difficulty putting my finger on it, but the Crees make it definitely sound better to my ears.
Modded Crack - add bypass cap, choke and Cree diodes
- Thread starter ALL212
- Start date
Jeb Jeb
New member
Hi Gunter,
Yes Parts Connexion don't seem to have any real-time stock control, so I just place an order and then they email me and let me know if any items are out of stock. They have been out of stock of these since late last year. I've checked in with them every 5 weeks or so, but no luck. They mentioned that everything is still way behind after Chinese new year. I'm not in a hurry but thought I would check here just in case....
I think I'm sorted now - this community is awesome.
Yes Parts Connexion don't seem to have any real-time stock control, so I just place an order and then they email me and let me know if any items are out of stock. They have been out of stock of these since late last year. I've checked in with them every 5 weeks or so, but no luck. They mentioned that everything is still way behind after Chinese new year. I'm not in a hurry but thought I would check here just in case....
I think I'm sorted now - this community is awesome.
For anyone curious, I e-mailed Parts Connexion and they told me the PCB for this mod is back in stock!
Google "Discrete Bridge Rectifier PCB - TYPE 2 (TO-220 Radial Style)," and it's the second link.
I ordered mine and will post my impressions once installed. Happy listening and take care!
Google "Discrete Bridge Rectifier PCB - TYPE 2 (TO-220 Radial Style)," and it's the second link.
I ordered mine and will post my impressions once installed. Happy listening and take care!
ALL212
New member
One of our moderators posted that replacing any one of the existing diodes with just one Cree would do the job. I've done it to one of my kits - maybe the Reduction? You just have to be very careful of placement because of the tab. Remember that they do have to go in the correct way.
Might be best to start a new thread so that you get attention to this before doing it?
Might be best to start a new thread so that you get attention to this before doing it?
Paul Joppa
Moderator
This is not technically true. You can add a Schottky between the bridge of 4 diodes and the first filter cap, and that is widely thought to be effective.ALL212 said:
ALL212
New member
a year ago...somewhere in there... I bought another Crack and built it stock. Tried using my o'scope but it was not up to the task. I don't know the make/model but I didn't see any difference in wave forms. Now - I might not have been looking in the right place or had the scope on the right settings but I did have fun playing around, just no useable results.
My ears told me something good happened when I put that diode board in with the Cree's on the Crack.
Thanks Paul for the clarification on the right way to add a single Cree. (I'd best turn my Reduction over and see exactly what I did under there!)
Here's what I did under there... Solitary cap, red leg to furthest back resistor.
My ears told me something good happened when I put that diode board in with the Cree's on the Crack.
Thanks Paul for the clarification on the right way to add a single Cree. (I'd best turn my Reduction over and see exactly what I did under there!)
Here's what I did under there... Solitary cap, red leg to furthest back resistor.
You want to look at the power supply. Right at that first cap would be a good place. Maybe on the heater secondary too. Look for spikes. The UF4007 is an ultrafast recovery diode and should have only a very tiny recovery spike. The Schottky should have none. Will the Schottky remove a spike from another diode? I dunno about that. People have used tube rectifiers after a SS diode because they are slooow and thus filter out the quick spike. They do the same for the musical transients.
Paul Joppa
Moderator
Here is a site with some information on reverse recovery, which applies to non-Schottky diodes:
http://electronics.stackexchange.com/questions/13912/what-is-the-reverse-recovery-time-in-diode
The reverse recovery happens very quickly, which causes noise of a buzzy nature that radiates as radio waves and infects nearby circuits.
Schottky diodes (and vacuum diodes) do not have this mechanism, so they prevent the recovery from happening rapidly when placed in series with a regular junction diode - making the recovery spike insignificant.
http://electronics.stackexchange.com/questions/13912/what-is-the-reverse-recovery-time-in-diode
The reverse recovery happens very quickly, which causes noise of a buzzy nature that radiates as radio waves and infects nearby circuits.
Schottky diodes (and vacuum diodes) do not have this mechanism, so they prevent the recovery from happening rapidly when placed in series with a regular junction diode - making the recovery spike insignificant.
mcandmar
New member
It was the single schottky diode after a rectifier bridge that i don't understand, how could it possibly make any difference?
W2AEW did a great video demonstrating reverse recovery here, he is worth subscribing to as all his videos are great, though some get into RF voodoo which is over my head.
https://www.youtube.com/watch?v=SBqLOrlA7QI
W2AEW did a great video demonstrating reverse recovery here, he is worth subscribing to as all his videos are great, though some get into RF voodoo which is over my head.
https://www.youtube.com/watch?v=SBqLOrlA7QI
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