Hi
Thanks for adding me.
Does anyone have a schematic and parts list for a hs treble booster?
welcome to the forum,
its basically a clone of a clone of the Range Master. i suggest building some sort of rangemaster clone, but with a socket for the input capacitor and experiment with that value until you like what you hear.
cheers
Hi & Welcome.. :icon_wink:
(https://i.imgur.com/io3AwT5.png)
edit: 18.5 cap/frequency product only stands for this very particular input impedance (8k6) :icon_wink:
I believe there's some, er, spirited disagreement, shall we say, about what the "correct" Hornby-Skewes schematic is, including debate around whether the tranny should be silicon or germanium and/or both at different times (but I think consensus is that Aron's redrawn schemo that antonis posted is wrong about the JFET; allegedly the correct part number is 2N4061, a PNP silicon BJT, which was misread as 2N4861, an N-channel JFET). Additionally the lack of input/output caps on Aron's schemo is also an error (I assume it was antonis who drew in an input cap there, and fair play for that). So I suppose caveat emptor or buyer be weird, as one will. Me, I like a good treble booster just fine, but I'm not ready to bring this one home to meet the parents just yet...
(deleted due to posting an incorrect schematic)
(deleted due to being needlessly ignorant)
Quote from: pacealot on June 17, 2022, 01:27:06 PM
I think consensus is that Aron's redrawn schemo that antonis posted is wrong about the JFET; allegedly the correct part number is 2N4061, a PNP silicon BJT, which was misread as 2N4861, an N-channel JFET). Additionally the lack of input/output caps on Aron's schemo is also an error
To be honest, low value bias resistors made me think the same.. :icon_wink:
Quote from: pacealot on June 17, 2022, 01:27:06 PM
(I assume it was antonis who drew in an input cap there, and fair play for that)
Any dark blue draw/text indeed is by Antonis.. :icon_wink:.
P.S.
IMHO, any treble booster can equivalently be considered as bass attenuator..
Quote from: pacealot on June 17, 2022, 01:47:10 PM
Here's an alternative schematic from elsewhen:
(https://i.postimg.cc/1gj9FQDH/hornby-skewes-treble-booster-2n4-1.gif) (https://postimg.cc/1gj9FQDH)
That's wrong. It should be 0.001µF on the output, 0.022µF on the input.
These should be correct:
(https://i.imgur.com/IWmmTRZ.png)
(https://i.imgur.com/AMafzlg.png)
I'm not sure what we're talking about but, in case of BJT device (either Si or Ge), in & out caps can readily be estimated by respective impedances, which are about 7k5 for input (hFE dependent) and 3k7 for output..
22nF cap for input results into 963 Hz corner frequency and 1n for output results into 43kHz..!! :icon_eek:
(the former might be Ok but the later calls for a -21dB attenuated(*) signal in the region of 5kHz, -27dB at 2k5Hz and so on..)
(*) compared to theoretical Collector output..
They were very consistent with that output cap ;D
And it works alright that way. Not the greatest sounding booster, but not bad either.. I haven't built the germanium version yet, though..