Modding Amps with Low Power

[Jeff5]

Does anyone have any experience with this? For instance if I wanted to take a 100Watt amp and get it modded to cut to 25/50/75/100 watts. I really like the cranked tube amp sound and power tube distortion, but also want the flexibility to have higher wattages just in case! How hard of a mod is this? Or how expensive is it to get a tech to do this? Anyone know or have any experience with it?

[lastwinj]

Re: Modding Amps with Low Power

pull either the outside pair or inner pair of power tubes to get half power. you will need to put the speaker on the next lowest output tap, if im not mistaken (i always forget)

good luck

germ

[lastwinj]

Re: Modding Amps with Low Power

oops, forgot.

but doing this wont get you what you want. either less efficient speakers, or a different power amp section/power supply would need to be done.

germ

[jeremy]

Re: Modding Amps with Low Power

pulling a pair of tubes will cut output but not by half, itll take a 100w amp down to maybe 60-65w or so. you do have to change the impedance, so if you are running a 16 ohm load run the amp on 8 ohms.

there are a couple ways to cut power and i dont think any of them are easy to do. how were you gonna go about it?

[Jeff5]

Re: Modding Amps with Low Power

I'm not sure if its something I'd even want to tackle myself. I actually have a power amp (Mesa 50/50) with a low power setting already. I just wondered why more amps don't give you the ability to switch between power settings, say 25, 50, 75, 100 (I know that wouldn't be exact), in order to get power tube saturation in different venues. Is this really hard/expensive to do? I also thought about if I ever buy a 100 Watt head and I want to have this done if it would be cost prohibitive. (based on what you guys are saying not sure if I'd want to do it myself)

[aleclee]

Re: Modding Amps with Low Power

Why would you want to do this as opposed to running an attenuator?

[y2stevo]

Re: Modding Amps with Low Power

Because an attenuator does suck some tone where as cutting power satutarts a tube more at less volume without loss of tone

[lastwinj]

Re: Modding Amps with Low Power

I'm not sure if its something I'd even want to tackle myself. I actually have a power amp (Mesa 50/50) with a low power setting already. I just wondered why more amps don't give you the ability to switch between power settings, say 25, 50, 75, 100 )

because with different power levels, the plate impedance changes. output trannies are usually designed for one impedance and power level. going above or below the impedance and the power level (current the ot will pass safely) will alter tone, quite a bit usually. not to mention, you arent willing to pay for that kind of flexibility. it would add considerably to the cost.

germ

[kevlar3000]

Re: Modding Amps with Low Power

Your not gonna get more than 3 db cutting to two tubes. Plus you lose all your bottom end. I have a Weber Mass and run my amps wide open in the studio and attenuated every where else. At gigging volumes the Mass is perfect, I lose a bit of sustain but the integrity of the tone is there through my non master heads. I only see issues when it is at the highest levels, which I never use anyway. Another option would be a PPIV master volume such as Dave Bray uses with his Plexi's. Those can sound really nice.

[mrid]

Re: Modding Amps with Low Power

Another option would be a PPIV master volume such as Dave Bray uses with his Plexi's. Those can sound really nice.

I second this option. Either Ken Fisher's PPIV circuit, or the "rich mod."