![[-]](https://theultimatetone.com/images/collapse.png "[-]")
11-14-2018, 10:31 PM
Hi Vostre Roy
There are countless things you can do with LP-PRE as TUTs show, where it is the LPSP - London Power Standard preamp.
The "low hanging fruit" of options:
>> make each Ck switchable
>> make the attenuator high-frequency emphasis switchable
>> add a bright cap to either/each channel and make it switchable
>> make the lead-channel interstage attenuator variable
Ck out of play reduces broadband gain for the first and fourth stages, and reduces high-frequency gain in the second and third stages. Making the interstage attenuator variable if done properly only reduces gain - there is a sweet spot of attack before hitting grid-rectification where the attenuator values are set at the moment.
Adding a Gain control to the clean channel has what goal? Do you want to be able to reduce gain? Increase gain? Get an overdrive tone from the clean channel? There are actually a lot of options, most of which would involve having bypassable or liftable controls, or modifying LP-PRE to be like the Ultra-Low-Noise version of LPSP shown in TUT. This would let you move the clean EQ and have a Gain between the clean channel stages and a Level after the EQ. Only mild overdrive is possible unless you add a bounding network or Power Scale the second clean stage.
Other mods are to add a bounding network to the Lead channel, or change the plate Rs or cathode Rs - switching either of these live will cause a POP!
You might want to build the preamp per the note first and try it out. This gives you a base line to work from, and you can make a list of tweaks to do, or features to add "need more of this", "need less of that".
There are countless things you can do with LP-PRE as TUTs show, where it is the LPSP - London Power Standard preamp.
The "low hanging fruit" of options:
>> make each Ck switchable
>> make the attenuator high-frequency emphasis switchable
>> add a bright cap to either/each channel and make it switchable
>> make the lead-channel interstage attenuator variable
Ck out of play reduces broadband gain for the first and fourth stages, and reduces high-frequency gain in the second and third stages. Making the interstage attenuator variable if done properly only reduces gain - there is a sweet spot of attack before hitting grid-rectification where the attenuator values are set at the moment.
Adding a Gain control to the clean channel has what goal? Do you want to be able to reduce gain? Increase gain? Get an overdrive tone from the clean channel? There are actually a lot of options, most of which would involve having bypassable or liftable controls, or modifying LP-PRE to be like the Ultra-Low-Noise version of LPSP shown in TUT. This would let you move the clean EQ and have a Gain between the clean channel stages and a Level after the EQ. Only mild overdrive is possible unless you add a bounding network or Power Scale the second clean stage.
Other mods are to add a bounding network to the Lead channel, or change the plate Rs or cathode Rs - switching either of these live will cause a POP!
You might want to build the preamp per the note first and try it out. This gives you a base line to work from, and you can make a list of tweaks to do, or features to add "need more of this", "need less of that".
