Bonjour à tous, je voulais savoir si l'un de vous a déjà utilisé la "méthode Rivera" pour régler le Bias?
on pouvait la trouver sur l'ancien site Rivera, et sur les sites de Fans tels que Sott Brown ou Ric Johnson. Le problème c'est qu'elle a disparu de tous ces sites. (on peut encore la trouver ici
http://fr.scribd.com/doc/12870(...)-docx )
Les questions que je me posais sont:
- est-ce qu'il y a un problème avec cette méthode (fort simple) pour qu'elle disparaisse?
- il faut débrancher le HP, or à ma connaissance, allumer un ampli lampe sans HP c'est bobo le transfo de sortie. quelqu'un aurait-il une idée sur ce qui permettrait de le débrancher dans ce cas?
pour ceux qui veulent un résumé, voici un extrait de la méthode Rivera:
Citation:
Un-plug the speaker cable - this is important.The Rivera method is opposite of most in that it requires that the first speaker jack has no connection. If your amp has a Modern/Vintage (or Pentode/Triode) switch make sure it is in the Modern (Pentode) position.WARNING - be very careful inside the amp. Do not poke around with your fingers. You can seriously hurtor even kill yourself by touching the wrong component.With the amp open and the circuit board facing you, locate the bias pot. This is generally a small black plastic part with a white screwdriver adjustment in the middle. This is how you adjust the flow of current toyour power tubes and "bias" the amp.The Bias Pot looks something like the above.Make sure the amp is turned off before starting.
Biasing to Rivera's Recommendations
Clip the negative (black) probe of the DVM to the chassis of the amp. The positive (Red) lead needs to beconnected to pin 8 of one of the power tubes. These connections are not easy to clip to. Fortunately, you canclip the positive lead to a connection on the Speaker jack output board. Locate the Speaker one jack anddirectly behind it you will find a small black wire connected to the board. Connect your DVM positive leadthere. Set the DVM to the Auto Voltage setting and turn it on.Make sure there is nothing connected to the speakers jacks of your amp. Connect the power cord and turn
on the power switch. Wait a minute and turn on the stand by switch. Let the amp warm up for a minute or two. Read the DVM meter. If it is fluctuating over a large range then wait a while longer until it settlesdown. Once it is stable or fluctuates only a little bit you are ready to adjust your amp.A good place to start setting your bias is with the Rivera defaults. Use the following settings from theRivera FAQ as a starting point:R30 and Chubster 40 Models are set to 70 MADC Total for both tubes, or 35 MADC for each.All of our 55 and 60 Watt Output Stages are set to 80-85 MADC for both tubes, or 40-42.5 MADC for eachtube.All of our 100 watt models are set for 160-170 MADC for all 4 tubes, or 40-42.5 MADC for each.Locate the bias pot and adjust the pot until the DVM reads within the above values for your model of amp. Now you have your amp properly biased!
