like the new tiny terror that goes from 7watts or 15watts.

how is this accomplished?

kerble at will,

and let me know.

thanks techroom

Possibly switches the output valve(s) from pentode to triode mode. It affects the sound in some ways.

Roddy

the three ways I've seen amps accomplish this are (in what I believe to be decreasing order of commonality)

1) the aforementioned pentode/triode switch

2) switch that enables/disables one of the two pairs of output tubes

3) "sensitivity" switch that affects the gain of the phase invertor/output driver tube. (not a half-power switch, just a minor output level adjustment)

I know Mesa used #2, and the only place I've seen #3 is in the Sound City 120 MkIV (blech)

if it's a cathode-biased amp, can't this also be achieved to some degree by switching the value of the cathode resistor? not sure on that one.

I don't know the Orange so I can't say what it's doing without seeing a schematic

on a slightly related note...

you might wanna check out London Power's "Power Scaling" kits etc...it's a pretty interesting concept and you can add it to any amp.

http://www.londonpower.com/pscaling.htm

outoftune wrote:on a slightly related note...

you might wanna check out London Power's "Power Scaling" kits etc...it's a pretty interesting concept and you can add it to any amp.

http://www.londonpower.com/pscaling.htm

I thought I remembered there being a limit on maximum plate voltage, but haven't checked out that stuff in a while. I think it's a great concept, basically intended to let your amp sound like your amp at whatever volume you want, which is something tube amps are generally not able to do well.

The tiny terror power switch has something to do with switching a tap on the transformer to change the voltage. I'll see if I can dig up the schematic.

Other amps switch out sets of power tubes, for amps with 4 or more power tubes. The Carr slant 6 V has a great system. It has 4 6V6tubes. One pair is run cathode biased at 18 watts. The other pair is run fixed bias at 22 watts. You can run either pair separately, or combine them for 40 watts.

Cheers!

Ben

There's the schematic.

The TT also has the cool ganged gain pot, so when you turn out the gain, you increase the gain from the first to the second sage, and from the second stage to the phase inverter. I like the elegance of this circuit.

Ben

Scott wrote:the three ways I've seen amps accomplish this are (in what I believe to be decreasing order of commonality)

And adjusting the HT voltage as per Ben's suggestion. This can be made to be constantly variable with a pot by using a MOSFET in a simple circuit for smaller amps.

I can't see the switch for adjusting the HT in the Orange schematic though - the switch at the power supply just appears to be a standby switch.

scott wrote:

outoftune wrote:on a slightly related note...

you might wanna check out London Power's "Power Scaling" kits etc...it's a pretty interesting concept and you can add it to any amp.

http://www.londonpower.com/pscaling.htm

I thought I remembered there being a limit on maximum plate voltage, but haven't checked out that stuff in a while. I think it's a great concept, basically intended to let your amp sound like your amp at whatever volume you want, which is something tube amps are generally not able to do well.

i guess the newer kits should be able to handle most normal amps:

The DC-PSK-1 is used for any fixed-bias amp up to 500W and/or with up to 700Vdc supplies. For cathode-biased amps up to 120W and/or with plate supplies up to 525Vdc, use the DC-PSK-2.

I might get one for my YBA-1 after I get it recapped. I will let you guys know how it is.

thanks for all the replies,
i'll try to come up with some good questions after i re-read the thread.

i only bring up the tiny terror because it was the only amp i could think of at the time that featured this.

i'm thinking about building a 15/30 watt tube combo amp,
1x12alnico, varitone eq no master volume
with a seperate slave solid state amp to cover the extra buns that a bass/baritone might want need..

i'll make a thread for it after i've got some idea which circuits i'm going to rip off/modify.

thanks again.