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DIY Stompboxes => Building your own stompbox => Topic started by: iainpunk on October 10, 2018, 03:19:39 PM

Title: Any use for leftover opamp?
Post by: iainpunk on October 10, 2018, 03:19:39 PM
I'm building a wave folder with tone and gain controls.
The schematic is this;

(https://i.postimg.cc/tYR0Xsq8/IMG_20181010_211215.jpg) (https://postimg.cc/tYR0Xsq8)

Part A is an active ""reversed big muff"" tone control
Part B is going to be a 1 to 10(not shure yet) times boost
Part C is the wave folder, which... Well, folds the waves...

This leaves me with one extra opamp on the IC. Do you guys have a suggestion for its use? Was maybe thinking about a voltage follower after the V+/2 section and make Vb the output of that opamp, but it already works great without this stabilization...

Thanks in advance,
Iain
Title: Re: Any use for leftover opamp?
Post by: mth5044 on October 10, 2018, 03:25:33 PM
You can buffer your Vb by connecting the + input to the junction of the two 10k resistor divider, connect the - input/output together and have that be your new Vb.
Title: Re: Any use for leftover opamp?
Post by: EBK on October 10, 2018, 03:37:14 PM
My very first post on the forum asked something very similar.   :icon_biggrin:

https://www.diystompboxes.com/smfforum/index.php?topic=115935.msg1071746#msg1071746
Title: Re: Any use for leftover opamp?
Post by: marcelomd on October 10, 2018, 04:09:06 PM
+1 on the clean blend.
Title: Re: Any use for leftover opamp?
Post by: PRR on October 10, 2018, 08:07:03 PM
Dual opamp.
(https://i.postimg.cc/7J97wfLV/iainpunk-1.gif) (https://postimg.cc/7J97wfLV)
Title: Re: Any use for leftover opamp?
Post by: iainpunk on October 11, 2018, 07:54:32 AM
Im not a big fan of a clean blend for a wave folder, since it already leaves a lot of the clean sound in tact, especially with a higher gain setting.

Quote from: EBK on October 10, 2018, 03:37:14 PM
My very first post on the forum asked something very similar.   :icon_biggrin:

https://www.diystompboxes.com/smfforum/index.php?topic=115935.msg1071746#msg1071746

This thread is sadly not very populated with answers BUT, the active tone control is a thing i didn't think about yet. Especially because there's already another one before the folder.
Im probably going for the ts9 tone control for now, second option is to change it to a passive big muff tone control on a dual gang with the first tone control, but making it do the opposite of the active one...

A buffered Vb is not my preference, since the rest already works with an unbuffered Vb.

I like the dual opamp design PRR drew up! I think that might become the "standard" version (adding a passive trebble cut) and the quad opamp becomes the deluxe edition.

Im not set in my decisions yet, but thank you for your submissions so far  :icon_wink:

Grts, Iain
Title: Re: Any use for leftover opamp?
Post by: antonis on October 11, 2018, 08:02:45 AM
Quote from: iainpunk on October 11, 2018, 07:54:32 AM
I like the dual opamp design PRR drew up! I think that might become the "standard" version (adding a passive trebble cut) and the quad opamp becomes the deluxe edition.
Deluxe edition could use leftover amp for mids..
(like in Wampler Triple Wreck..)
Title: Re: Any use for leftover opamp?
Post by: iainpunk on October 12, 2018, 09:26:19 AM
Quote from: antonis on October 11, 2018, 08:02:45 AM
Quote from: iainpunk on October 11, 2018, 07:54:32 AM
I like the dual opamp design PRR drew up! I think that might become the "standard" version (adding a passive trebble cut) and the quad opamp becomes the deluxe edition.
Deluxe edition could use leftover amp for mids..
(like in Wampler Triple Wreck..)

There is already a mid booster functionality in the pre folding tone circuit, i think a mid boost after could be a overkill.

I think I'm going to use a tube screamer tone circuit after the folder. Boosting the trebble could work out well after the folding to make it even more suitable for my noise pop band, but thanks for the suggestion.

Grts
Title: Re: Any use for leftover opamp?
Post by: iainpunk on October 18, 2018, 10:13:29 AM
Ive breadboarded the pedal... again...
After some playing around i found that because of the wave folder's high amount of higher order (dis)harmonics it sounded and felt a bit too mid scooped, so instead of a "normal" tone control, i have chosen an adjustable mid boost around 666Hz (yeah, i know, its a bit edgy) of 0 to 20 db with a rather low Q facror.
The schematic is as follows:
(https://i.postimg.cc/BLngghLW/IMG-20181018-161117.jpg) (https://postimg.cc/BLngghLW)
Title: Re: Any use for leftover opamp?
Post by: antonis on October 19, 2018, 05:07:43 AM
Quote from: iainpunk on October 18, 2018, 10:13:29 AM
i have chosen an adjustable mid boost around 666Hz (yeah, i know, its a bit edgy)
Not edgy at all.. :icon_wink:
(640Hz is the mid of audible frequency spectrum octaves..)
Title: Re: Any use for leftover opamp?
Post by: iainpunk on October 19, 2018, 05:34:26 AM
Quote from: antonis on October 19, 2018, 05:07:43 AM
Quote from: iainpunk on October 18, 2018, 10:13:29 AM
i have chosen an adjustable mid boost around 666Hz (yeah, i know, its a bit edgy)
Not edgy at all.. :icon_wink:
(640Hz is the mid of audible frequency spectrum octaves..)
Yeah, i was aiming at 650Hz but using the closest e12 values, i came out at 666.459Hz, it works great though