Yamaha - NE-1 Parametric Equalizer

lolbou · Post by **lolbou** » 26 Aug 2009, 07:43

Looking at the units you pointed out AG, I realized that they have NP caps before the tone stack...

Which was what Silentfly note down on his pics!

Schem updated to version 1.1.

NE-1 - schematic 1.1.pdf: (90.73 KiB) Downloaded 481 times

Thanks!

ps: can anyone delete the older versions? Or leave them for awhile waiting for further corrections/improvements?

george giblet · Post by **george giblet** » 26 Aug 2009, 08:56

> Schem updated to version 1.1.

Something went wrong with the first switch on that version.

The circuit is a just a variable frequency notch filter. The switching at the front end makes the first stage gain unity in bypass mode and tweaks the gain to be above units when the notch is in place - the idea here is the notch sucks out some signal and the small increase in first stage gain tries to compensate for this so the perceived level is the same. (The gain compensation is used in quite a few bass amp "voicing" circuits which often incorporate fixed notch circuits.)

lolbou · Post by **lolbou** » 26 Aug 2009, 09:16

george giblet wrote:> Schem updated to version 1.1.

Sorry about that...

Right George, the NP cap should link the common pole of the first switch...

Corrected...

Version 1.2

NE-1 - schematic 1.2.pdf: (90.86 KiB) Downloaded 488 times

Dirk_Hendrik · Post by **Dirk_Hendrik** » 26 Aug 2009, 10:34

The 470k resistors do not go to the battery supply but to a half vcc bias supply made by R5, R6 and C4.

lolbou · Post by **lolbou** » 26 Aug 2009, 11:07

Dirk_Hendrik wrote:The 470k resistors do not go to the battery supply but to a half vcc bias supply made by R5, R6 and C4.

You mean the B+ on my schem? To me it's already like that on my drawing...

What am I missing?

DimebuGG · Post by **DimebuGG** » 26 Aug 2009, 12:17

estragon · Post by **estragon** » 26 Aug 2009, 13:46

Cool!
Only thing that looks strange is that in the FLAT position you need to dime tha LEVEL pot so as to have unity gain.

Silent Fly · Post by **Silent Fly** » 26 Aug 2009, 14:16

Thanks everybody for tracing the circuit.

It is a nice little box. It is a little bit boomy (especially in the "deep" setting) but apart from that it is worth build it.

tube-exorcist · Post by **tube-exorcist** » 26 Aug 2009, 14:23

You can use a more common 3-position 2-pole toggle switch instead of the rotary switch.

DimebuGG · Post by **DimebuGG** » 26 Aug 2009, 15:14

tube-exorcist wrote:You can use a more common 3-position 2-pole toggle switch instead of the rotary switch.

a DPDT with center off toggle switch will do...

Dirk_Hendrik · Post by **Dirk_Hendrik** » 26 Aug 2009, 17:05

I guess i'm blind but where does that 8n2 value come from?

Dirk_Hendrik · Post by **Dirk_Hendrik** » 26 Aug 2009, 17:06

lolbou wrote:
Dirk_Hendrik wrote:The 470k resistors do not go to the battery supply but to a half vcc bias supply made by R5, R6 and C4.
You mean the B+ on my schem? To me it's already like that on my drawing... What am I missing?

B+ is vcc, the battery voltage. Those 2 470k resistors are not connected to b+. I think you swapped the 2 red wires on the photo's

Silent Fly · Post by **Silent Fly** » 26 Aug 2009, 17:51

Dirk_Hendrik wrote:I guess i'm blind but where does that 8n2 value come from?

It is C5. I wrote "B22K". I just realised it should be "822K".

The "8" looked very much like a "B".

lolbou · Post by **lolbou** » 26 Aug 2009, 18:19

Silent Fly wrote:It is C5. I wrote "B22K". I just realised it should be "822K".

The "8" looked very much like a "B".

Yes, I translated it... I thought that a two-legged green 22k linear pot was too weird...

Dirk_Hendrik wrote:The 470k resistors do not go to the battery supply but to a half vcc bias supply made by R5, R6 and C4.

The B+ on my schem comes from the 39k/47k network (R5/R6 divider for biasing)... You mean I should have called it 1/2Vcc (even if it's not exactly 1/2) instead of B+?

To get rid of my colorblindness, I used the Wx wire names...

Dirk_Hendrik · Post by **Dirk_Hendrik** » 26 Aug 2009, 18:20

Me stupid too

Silent Fly · Post by **Silent Fly** » 27 Aug 2009, 14:58

I hope it is of some interest - it looks like bassists are a tiny minority here.

I modded the NE-1 I recently purchased second-hand. At least with my basses the DEEP setting was far too extreme. Now I can get much more musical and useful sounds.

C6: removing C6 makes the 3 "Q" settings at the same volume. It is much more practical than constantly moving the volume knob to compensate volume variations.

Depth control/filter type: I added a double pole 3 position switch (on-off-on). In position 1, the NE-1 operates normally. In positions 2, C5 and C7 are removed from the circuit; the NE-1 operates as a variable LP filter. In position 3, the NE-1 has two new more subtle (and usable) sounds for shallow and deep.

Some of original settings of the NE-1 are not too bad but with a modded version I can get all the type of sounds I like from slap-machine sounds, to more fingerstyle sound (Jaco-like), to ultra-deep.

Silent Fly · Post by **Silent Fly** » 27 Aug 2009, 15:01

If you plan to build a NE-1, you may find this version interesting.

The Q control varies continuously and a switch changes the filter to low-pass.

: Yamaha NE-1 (Silent Fly remix)

OldMan · Post by **OldMan** » 28 Aug 2009, 00:48

Hello all
Im OldMan a new Bassman here, my first post, I'm from Switzerland,

I can't see the sense of R12 can enyone explain please?

Thanks
OM

george giblet · Post by **george giblet** » 28 Aug 2009, 04:03

> I can't see the sense of R12 can enyone explain please?

Prevents opamp oscillation with capacitive loads. (Also has benefits for shorts, ESD, RF.)

OldMan · Post by **OldMan** » 29 Aug 2009, 01:00

Thanks vor explaining

Perfboard anyone?

Yamaha - NE-1 Parametric Equalizer [schematic]