BoR

JHS · Post by **JHS** » 28 Jul 2007, 15:24

I like the Booster in the BoR but I didn't want to buy a Rev log pot. Some other things bugged me too on this circuit design, so here is my custom version of this booster. The 150n XICON sounds really good in this circuit, IMHO a PIO-cap sounds even better, but I didn't want to waste such a good cap it in this circuit.

JHS's CUSTOM_Mosfet_Booster

With the XICON and the MKT caps the booster sounds more natural, not so artificial than the original.

BTW: the 1,5uF MKT has the dimension of a 38-special cartridge.

JHS

(edited by admin: cleaned up dead link)

markusw · Post by **markusw** » 28 Jul 2007, 16:43

Thanks for sharing your work!

How does the Hi_cut work? At a first glance I'd assume it acts a bass cut.

Regards,

Markus

JHS · Post by **JHS** » 28 Jul 2007, 18:26

It is a decent high-cut (similar to 10k/100k on the output of a TS-808/9).

JHS

markusw · Post by **markusw** » 29 Jul 2007, 06:57

JHS wrote:It is a decent high-cut (similar to 10k/100k on the output of a TS-808/9).

JHS

How does it work?

Post by **modman** » 29 Jul 2007, 11:48

Great contribution!
That booster stage in the Box of Rock is of course, the Super Hard On booster.

maybe a reference to the SHO would have been a better title, or why not JHS Custom mosfet booster?

JHS · Post by **JHS** » 29 Jul 2007, 15:32

I decided to go with the BOR-Boost as a basic, the SHO is to treble for my taste but I must agree that the BOR-boost is a modded stock SHO (modded for 1M input impedance).

The high cut loads down the input of the amp, more or less.
With the pot fully open the loading is lesser, so a bit more treble gets through. It's very decent but it's enough to cut down the high frequencies.

Those BS170 stray a lot in frequency response and output, some sound really icepicky and the high cut can tame it a bit.

I prototyped the booster from the schem with the 2 914 diodes too, but some BS170, depending on the manufacturer, will not work in it, .

Soundwise there is not much difference, so I recommend to build the SHO or BOR-boost acc. to the schem with the protection diode running from souce to the base (this circuit works with every BS170 I checked so far).

When I have time, I will build onother prototype with "noiseless" biasing (like the AMZ Mosfet booster) , just to check out how it sounds.

JHS

markm · Post by **markm** » 29 Jul 2007, 16:31

modman wrote:Great contribution!
That booster stage in the Box of Rock is of course, the Super Hard On booster.

Yeah, that SHO gets alot of mileage.
I still think it's a good sounding booster but my-oh-my,
It's been kinda overused to the point where it ought to be limp
by now I would think!!

markusw · Post by **markusw** » 29 Jul 2007, 17:07

The high cut loads down the input of the amp, more or less.
With the pot fully open the loading is lesser, so a bit more treble gets through. It's very decent but it's enough to cut down the high frequencies.

Thanks!!