Hallo liebe Gemeinde,
mein Name ist Alex,ich komme aus dem südosten Bayerns und bin 43 Lenze jung/alt.
Lese schon einige Jahrehier im forum mit und habe el.techn. Grundkenntnisse.
Bisher konnte ich wenns Probleme mit meinen Amps gab immer irgendwie eine
Lösung durch recherchieren finden.Bei meinem aktuellen Problem bräuchte ich
jetzt doch etwas Hilfe.
Der Pegel im FX Loop meines JCA20H(V) ist viel zu hoch für meine Bodentreter,
auch wenn nix im Loop hängt verstärkt dieser zu sehr.(Getestet,Loop abgehängt)
also was tun?den spannungsteiler vorm ic830 ändern?ein send level poti(an welcher stelle,Wert?)
einbauen?
hier mal was ich bisher gefunden habe zu diesem Effektweg:
"The question about the B+ was asked more than once, so I looked for a limiting factor on the schematic. If the 47K on the IRF830 Source is 1W, the maximum voltage it can take is 216Vdc. I don't own an IRF830 to test, but the Gate is probably around 218V if the Source is 216V. The 1M : 10M voltage divider will make it about 238V on the power rail. 216V across 47K is 4.6 mA and the LND150 will bring the total consumption up to an even 5mA. 5mA across the 10K/2W dropping resistor is 50V. 50V plus 238V is 288V which is the maximum B+ before the 47K exceeds its 1W rating.
Another thing to note about the IRF830 being biased so hot is that it doesn't have far to go before it clips. If the power rail is 238V and the IRF830 is idling at 216V, the theoretical maximum positive signal swing before clipping would be 22V peak. At lower B+ voltages the headroom is even smaller. So why the 1M : 10M voltage divider? The input impedance is the 1M resistor in parallel with the 10M resistor, so maybe it is to achieve a high input impedance. But a 1.8M : to 1.8M divider will give the same input impedance, take the strain off of the 47K resistor, allow a higher B+ voltage (which the LND150 needs), and reduce the current consumption by nearly half. Of course now the negative side of the signal will clip at about the same peak voltage as with the 1M : 10M divider, so there is little to no improvement in headroom. Maybe I'm missing something here, but If I weren't concerned about headroom I would certainly choose the 1.8M : 1.8M divider.
If you are ordering parts, you also might consider changing the 10M resistor to a 4.7M and changing the 47K to a 2-watt variety. The 4.7M will allow a much larger signal swing for the send before clipping. A 2-watt 47K resistor will allow the use of higher B+ voltages."
Der 47k Widerstand sieht bei mir auch etwas angekohlt aus....
Ach ja,die Loop sitzt bei mir zwischen Treble und dem 470k vorm Master.
LG,Alex
