Reverse engineering vintage Haz Labs pre

[AgingEngineer]

This is where I am pondering the best solution, as there are a couple paths:

1. Go the EMG route where I develop a separate active blend,
2. Add the decoupling cap and resister into the LHZ preamp design,
3. Offer a "system kit" with everything prewired.

I'm leaning toward the best path being exactly what you suggest: offer a complete system option with all pots already wired for those who just want to drop it in without worrying about wiring things themselves.

Everyone else who likes to tinker would just use the basic preamp and modify the wiring to suit their unique configuration. Currently, 60% of buyers are what I'd consider DIY electricians with unique needs who are wiring the LHZ preamp board in ways I never considered. I've even had a couple folks raise the idea of building it into a stompbox for passive basses, and I think one of them is actually working on that now.

 

[Jim C]

My suggestions is to offer a pre-wired kit for a direct replacement into NS2 and NS2A (Korean) basses.
This could also be a hot rod kit for other 2 pup builds.
My older NS2A with active EMG's does not have quick clip connectors on the pups but does have a blend pot. I think there are a bunch of folks in this category and Spector will not support the 2A.

 

[fibz]

Currently, 60% of buyers are what I'd consider DIY electricians with unique needs who are wiring the LHZ preamp board in ways I never considered.

Interesting, didn’t expect that. I was somehow convinced that most users would be EMG/Spector users who would just swap out the preamp for the LHZ.
Another solution instead of pins compatible to EMG’s connectors would be to offer that screw in thingy that Darkglass uses on their ToneCapsule. Most Euros and Koreans don’t come with the EMG connectors. That would make it easier.

 

[AgingEngineer]

My older NS2A with active EMG's does not have quick clip connectors on the pups but does have a blend pot. I think there are a bunch of folks in this category and Spector will not support the 2A.

I didn't know Spector is not supporting the 2A! That led me down a whole rabbit-hole of Spector history. It almost sounds to me the NS2A's fall into a similar camp as the Rebop. Great bass mechanically, but with the choice of pickups and electronics that come stock it just never really sounds as good as really it could.

Great point to kit this in a way that makes it clean drop-in replacement.

Another solution instead of pins compatible to EMG’s connectors would be to offer that screw in thingy that Darkglass uses on their ToneCapsule.

That's something I'd not thought of! I've not tried the TonCapsule, but reading this made me remember my electrician days when I was working on a lot of this automation coming out of Europe with these really slick terminal strips. You could just push a wire into it and it would grip it in a compression clip. Try to pull it out, and it would tighten down on the wire even harder. Releasing the wire just needed a small paperclip or screwdriver to press down a release tab. Those, or standard screw-terminals, will likely directly mount on the PCB as it is currently designed.

You and @Jim C just gave a bunch of fun things to work on this weekend, so I thank you both for the inspiration! This kind of conversation is why I love this forum!

 

[VeryTallBassist]

Terminal strips (or Phoenix style connectors) are the way to go. That way you're connector-agnostic with the pickups.

 

[bigbottomend]

Finally I got it wired up and working however I did need to switch the ring and tip on my switchcraft barrel jack around from the drawing. Maybe some barrel jacks are wired different or it may have been my mistake, however it made me smile when it worked.
On first listen .. just sounds like a Haz to me.. very happy with this and will get some recording done on it at some point in the future

 

[AgingEngineer]

I'm glad you got it working and am happy with the sound! I looked at the install diagrams to see if the T S R connections were transposed... They are correct, however I did notice something: I used a generic jack diagram in the installation manual wiring.

I'll bet that the order of the connections (TSR) on the generic jack are not in the same order as the pins found on the Switchcraft jack that all the the Spectors have! I'll confirm that and update the manual to show the Switchcraft instead of a generic jack.

Thank you for the update, and am looking forward to hearing some recordings!

 

[dougfr67]

Based on the sound samples it's a very cool sounding Haz clone.
I have only one suggestion:

I've seen some users using velcro or double sided tape all over the PCB.
Wouldn't be a good idea to make a slightly bigger board just to have space for four mounting holes or placing the velcro or double sided tape on the corners?

It would make repairs much easier.

 

[byacey]

I have got a master degree in electronics (RF).
Actually I do not need LT spice just to prove and evaluate schematics. But it makes it way more easier to demonstrate the principle of working of "schematics" on forum discussions.

Addressed to all of those who intend to search for mystical things, I don't feel responsible for incomprehension of signal theory.



Most of amateurs and hobbyists try to evaluate a schematic with sinusoidal waveform, yet the real practice is way more complex than it looks like with an idealized signal waveform.


Congrats!
Yet in first instance, I try to trust in my own ones.
At the other hand side, at the age of 62 I have to admit that hearing was better at the age of 40, yet more experience at the age of 50.


Personally I almost always think I do know what I'm hearing. Yet sometimes the ears can be very tricky. At least I'm aware they can be very tricky at some time.



Agreed.
And that's the reason what I always tried to to tell in previous threads. The NS2-O (see my avatar) does sound more "organic" due to its different OP-amp, rather than because the oil finish and where there is no varnish that might lock the tone/vibration of the wood

A square wave for testing will reveal more of what is happening than a sine source.

 

[fibz]

I'm glad you got it working and am happy with the sound! I looked at the install diagrams to see if the T S R connections were transposed... They are correct, however I did notice something: I used a generic jack diagram in the installation manual wiring.

Maybe that’s the reason why my battery run empty. Gotta check that too.

 

[fibz]

By the way, here are some samples of the LHZ working in an Euro 4LX and a SSD NS-5CR. No processing.

 

[bigbottomend]

View attachment 5126182 View attachment 5126183 View attachment 5126176 View attachment 5126181

Finally I got it wired up and working however I did need to switch the ring and tip on my switchcraft barrel jack around from the drawing. Maybe some barrel jacks are wired different or it may have been my mistake, however it made me smile when it worked.
On first listen .. just sounds like a Haz to me.. very happy with this and will get some recording done on it at some point in the future

Rough recording but here you go --->

 

[ThisBass]

A square wave for testing will reveal more of what is happening than a sine source.

It depends on what the design engineer in particular is looking for.
There are other "signal sources" as well such as burst, sweep and modulated signals and others more, each of them is suited to provide distinct purposes and outcomes.

 

[bonin in the boneyard]

I'm glad you got it working and am happy with the sound! I looked at the install diagrams to see if the T S R connections were transposed... They are correct, however I did notice something: I used a generic jack diagram in the installation manual wiring.

I'll bet that the order of the connections (TSR) on the generic jack are not in the same order as the pins found on the Switchcraft jack that all the the Spectors have! I'll confirm that and update the manual to show the Switchcraft instead of a generic jack.

Thank you for the update, and am looking forward to hearing some recordings!

Hey Lonnie, quick question. I'm going to install my preamp soon, but I have multiple basses I'd like to try it in, so I was thinking about properly connectorizing all my stuff. Would this kit be compatible with the headers on the preamp? If not, could you recommend a kit that would be? Thanks!

https://www.amazon.com/Crimping-AWG23-14-Self-adjustable-Terminals-Connectors/dp/B08D34JW68/

 

[ThisBass]

Add the decoupling cap and resister into the LHZ preamp design,

IMO/IME there is no need for any decoupling cap.
The output buffers of active pickups are (almost always) already DC decoupled, thus there is absolutely no need for an additional decoupling device.
If I was in your shoes, rather than spending an additional decoupling cap that remains nothing I'd try to save some space on the board and keep the PCB as small as possible.

Personally I think that an additional HPF that was added to the schematic yet not decoupled from the EMG's HPF may make results a little bit unpredictable at some content.

 

[AgingEngineer]

Hey Lonnie, quick question. I'm going to install my preamp soon, but I have multiple basses I'd like to try it in, so I was thinking about properly connectorizing all my stuff. Would this kit be compatible with the headers on the preamp? If not, could you recommend a kit that would be? Thanks!

https://www.amazon.com/Crimping-AWG23-14-Self-adjustable-Terminals-Connectors/dp/B08D34JW68/

That kit should work just fine with the pin headers. The spacing is 2.54mm on the board, which matches this kit. I was actually considering getting the same set for test rigging in the shop. Cheers!

 

[Jim C]

If anybody has a minute, what does this pre sound like with fingerstyle play and an R&B / blues vibe?

 

[ThisBass]

If anybody has a minute, what does this pre sound like with fingerstyle play and an R&B / blues vibe?

Probably similar as is for any other different on board EQ as well.
You may be fine by just adding a little bit of Bass and Treble with the EQ knobs, or just leave the knobs at its center position and run the EQ board flat.
Personally I don't like the stock OP-Amp LF442 that much as others may do. I prefer the more generic/airy sound of the TL072 that was stock OP-Amp on the Cor-Tek boards (KHAZ).
Yet I may give a try for something different OP-Amp (more modern OP-Amp) such as LT1112 or LT1638 sometime.

 

[Jim C]

BTW, some of us got frustrated when their KHAZ boards died that they bought other KHAZ pre's in the hope that they worked. They don't.
I'm also having issues with my SNC pre. I'm nearly ready to try either an Audere or EMG BTS just to have a working bass. It's been dead about 6 years. HATE the fact that Spector will not even talk about these basses let alone sell a replacement pre. I would have taken a Tone Pump if it was offered for sale.

 

[dougfr67]

BTW, some of us got frustrated when their KHAZ boards died that they bought other KHAZ pre's in the hope that they worked. They don't.
I'm also having issues with my SNC pre. I'm nearly ready to try either an Audere or EMG BTS just to have a working bass. It's been dead about 6 years. HATE the fact that Spector will not even talk about these basses let alone sell a replacement pre. I would have taken a Tone Pump if it was offered for sale.

I don't see SNC here. I see 3 KHAZ and one HAZ. It literary says 'HAZ LABS' on the HAZ.