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Author Topic: Converting jFet overdrive circuit from 9 to 18V  (Read 16958 times)

Alexius II

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Re: Converting jFet overdrive circuit from 9 to 18V
« Reply #15 on: May 19, 2011, 06:38:39 AM »
Another small update:
I feel I've got the sound I wanted, so I decided to focus on the power amp now.
Since this will be a bedroom practice/recording amp, I figure I won't be needing more than 5W. Therefore I'll go with LM1875 with 2x15V, 30VA transformer. Preamp will be powered from + rail, regulated to 15V with LM7815.

So, if all goes ok, the next "update" will be photos/samples of the finished amp and the final schematic  :tu:
(in a few weeks or so)

Alexius II

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Re: Converting jFet overdrive circuit from 9 to 18V
« Reply #16 on: May 21, 2011, 10:13:29 AM »
This is the last post here  ;)

Today I connected the whole thing together and did one last test before I dismantle the whole thing and redo it properly (in a nice enclosure). I will not post any photos, because at the moment it looks like a chaotic array of dozens of wires connected to random small pcbs and perfboards all around my table  :lmao:

BUT, I did record two samples that show the different drive behaviour of my two "modes" or channels, if you want.

1. sample: the "modern mode". Preamp is basically dr.Boogey with some minor changes of res/cap values. Majority of distortion is generated before the tonestack. All controls are set to neutral (12 o clock), except for volume, which is at 9 o clock.

2. sample: the "classic mode". Preamp is the same, but with different first gain stage, and bypassed "cold" stage (much lower overall gain). Most of distortion is generated AFTER the tonestack by the mu-amp. All controls are maxed out (to get about the same amount of gain/distortion as in the modern sample).

On both samples the "bass boost" switch was engaged. Speaker was CL80 in an open-back 1x12. Two similar recordings, panned left and right. Riffs are some random heavy stuff, similar to what I play most of the time  :loco

Comments are welcome, as always!

Cheers! :tu:
« Last Edit: May 21, 2011, 10:14:53 AM by Alexius II »

joecool85

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Re: Converting jFet overdrive circuit from 9 to 18V
« Reply #17 on: May 23, 2011, 08:25:50 AM »
This is the last post here  ;)

Today I connected the whole thing together and did one last test before I dismantle the whole thing and redo it properly (in a nice enclosure). I will not post any photos, because at the moment it looks like a chaotic array of dozens of wires connected to random small pcbs and perfboards all around my table  :lmao:

BUT, I did record two samples that show the different drive behaviour of my two "modes" or channels, if you want.

1. sample: the "modern mode". Preamp is basically dr.Boogey with some minor changes of res/cap values. Majority of distortion is generated before the tonestack. All controls are set to neutral (12 o clock), except for volume, which is at 9 o clock.

2. sample: the "classic mode". Preamp is the same, but with different first gain stage, and bypassed "cold" stage (much lower overall gain). Most of distortion is generated AFTER the tonestack by the mu-amp. All controls are maxed out (to get about the same amount of gain/distortion as in the modern sample).

On both samples the "bass boost" switch was engaged. Speaker was CL80 in an open-back 1x12. Two similar recordings, panned left and right. Riffs are some random heavy stuff, similar to what I play most of the time  :loco

Comments are welcome, as always!

Cheers! :tu:

Only very subtle changes between the two really.  That said, I think I like the modern mode a bit more.  Excellent playing as well.
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