Sujet Sélecteur d'impédance : J'ai un doute stupide, mais j'aimerais être sûr.

Citation : You want to have the selector switch like you have it in the second
picture http://pulvoweb.chez-alice.fr/bazar/selectorright.jpg
I know it's kind of ambiguous. You always want the "slot" under the
selected impedance.
My only question to you is are you running 410HEs or 410HLFs. If
they
are 410HEs, you are correct. You need to have it set to 4 ohms.

Best Regards,

Dino

Citation : Ceci est vrai pour les amplis a transistors, sur du lampes y'a des transfos de sortie, et il faut respecter l'impédance

Hors sujet : Mais alors il y une chose qui me turlupine, j'ai une tête Fender Bandmaster Reverb de 1972 ( donc totalement a lampes ) avec une impédance fixe ( sans aucun sélecteur ), marquée à l'arrière "Maximum load 2 Ohms", et je l'utilise sur un cab 2x12" Marshall 8 Ohms depuis plus de 15 ans sans aucun problème!

Quelqu'un pourrait-il m'éclairer sur ce point?

Merci

Hors sujet : T'as sans doute ni la puissance ni la qualité sonore que tu aurais en 2 Ohms.
Et comme sur mon ampli, t'as probablement un transfo de sortie généreux qui a accepté de bosser sans cramer !
Je pense que tu devrais ouvrir un thread là-dessus au bon endroit. Y a surement des guitaristes calés en amplis à lampes qui te répondront. Envoie-moi le lien si tu le fais, ça m'intéresse.

Citation : J'ai le sentiment de passer du jouer en plastique à l'arme à feu réelle...

Citation : Si c'est écrit que 2 ohms passe avec ta sortie hp t'as pas à t'en faire en autan que tu reste entre 2 et 16 ohms de haut parleurs.

Hello,

First, the official answer:

No, you can only use the impedances that the output stage is expecting to see, which is either 2 or 4 Ω.  You must make sure to always have the switch in back of the amp, set to the appropriate impedance of your speaker system.  This is true for the majority of tube amps, as they need a matched load.

So, we do not recommend any other load other than the rated output loads of our amps.  In fact, if the unit is still under warranty, then ABSOLUTELY DO NOT USE ANY LOAD OTHER THAN WHAT IS LISTED IN THE OWNERS MANUAL, AS THIS WILL VOID THE WARRANTY!!!

Now for the “UN-official” opinion:

Some tube amps can handle a one step up or down in regards to impedances.  For example, a 4 Ω only output MAY be able to handle either an 8 or a 2 Ω load.

There are a few factors that play into this that you cannot control, like the design of the amp, but the tube quality plays a role as well.

NOS tubes seem to handle this much more than newer general quality (in other words, affordable) tubes, so it’s something to consider.

I know people who have run 8 Ω loads for years (on a 4 Ω tube output) without an issue, but I’ve also seen people blow the output stage from the same load.

It’s a risk, so it’s up to you.  I personally do not choose to play the ‘load differential’ game, as I am fully aware of the consequences.  Since a blown output stage is a very expensive fix, and would NOT be covered under warranty if due to an 8 Ω load, it’s a big decision.

I only give out this information as an effort to be realistic, not to recommend, so I repeat:

We do not recommend any other load other than the rated output loads of our amps.  In fact, if the unit is still under warranty, then ABSOLUTELY DO NOT USE ANY LOAD OTHER THAN WHAT IS LISTED IN THE OWNERS MANUAL, AS THIS WILL VOID THE WARRANTY!!!