bartolini NTMB veroboard

[funkbass187]

i was curious if there were any vero layouts for the bartolini NTMB preamp. I found a pcb layout, but i don't know how to  print the transfer for it from the layout that has been floating around. any help would be appreciated and worst comes to worse I'll attempt to make my own.

[funkbass187]

anyone?... I'm not at the level where i can understand the schematic to the point of making a layout for a circuit as complex as this one. but i suppose i could always learn.

[slacker]

If you post a link to the schematic I'll see if I can do a vero layout.

[funkbass187]

thanks for the help

[Paul Perry (Frostwave)]

A pair of back to back 820nF electrolytics in series with a 100nF??? that's pretty weird.

[markusw]

A pair of back to back 820nF electrolytics in series with a 100nF??? that's pretty weird.

The 100n was switchable with a push pull pot on the unit I traced. Does this make more sense? 
There is a list at the Bartolini homepage with different calues for C7 and the corresponding mid frequencies. I always used it with the 100n cap.

Markus

[funkbass187]

could you use a regular toggle switch for that cap, or does it have to be a push/pull pot?

[slacker]

A push/pull pot is just a switch attached to a pot, it works exactly the same as a having a separate switch and pot. So you can use a normal toggle. 
I'm away on holiday next week, so I won't have time to look at doing a vero layout, but I'll see what I can do when I get back

[funkbass187]

take all the time you need. I'm just greatfull that someone is even considering making a layout for that.

[Gabriel Simoes]

Hello markusw! how r u doing?!

Well guys, I have built this preamp more than a year ago and it works flawless .... the midrange is the most difficult step and I took sometime to find the right value for the cap, ... and well, to me it's range is too short (the gain and cut are too short).
But it works great, lots of gain ...

If someone wants, I have dont a layout for it using eagle and I may drop it here if needed, just ask.
It's a simple one, smaller than the original, one sided.

markusw, I think we should try to emulate this bandpass/bandstop with opamps so it would be a LOT easier to gather the parts together, and the shortness of the mid pot would be gone too .... an idea to think about ...

Gabriel

[markusw]

Hey Gabriel, 

I'm fine, thanks!  How are you?

My NTMB clone works now actually longer than I had the original unit (before it crapped out  ) LOL

the midrange is the most difficult step and I took sometime to find the right value for the cap

I added a 6x micro dip switch to my layout to choose values for C7 in the range from 10n to about 1µ. I didn't check it out that much but 100n (like in the original) sounded best to me. Maybe I should check again, I use a different bass amp now....Thanks for reminding me! 

and well, to me it's range is too short (the gain and cut are too short)

You mean there is not enough mid cut/boost? Hm, actually I'm fine with it's range. I think it might be cool to have some custom tapers to make the pots respond faster. Maybe with some tapering resistors?

I think we should try to emulate this bandpass/bandstop with opamps so it would be a LOT easier to gather the parts together,

Great idea! Basically, it should be relatively easy to replace the inductors with a gyrator. There is a lot of information on R.G.'s site.
Question is: would it sound different than the real inductor? I don't have any experience with this...

Regards,

Markus

[Gabriel Simoes]

Well, it will depend on the filter we build .... but it will allow, for example, the use of hi mid / low mid concept ....
The bass / treble range is much bigger than the mid range in the unit I've built .... and the pots almost show no differente in 70% of it's axe ... much in the beggining and end (maybe I'm using the wrong pot type).

[blackbirdneo]

Hello markusw! how r u doing?!

Well guys, I have built this preamp more than a year ago and it works flawless .... the midrange is the most difficult step and I took sometime to find the right value for the cap, ... and well, to me it's range is too short (the gain and cut are too short).
But it works great, lots of gain ...

If someone wants, I have dont a layout for it using eagle and I may drop it here if needed, just ask.
It's a simple one, smaller than the original, one sided.

markusw, I think we should try to emulate this bandpass/bandstop with opamps so it would be a LOT easier to gather the parts together, and the shortness of the mid pot would be gone too .... an idea to think about ...

Gabriel

can you post or send me a copy of the layoutat my email(rolfocampo@yahoo.com)? thank you very much.

[funkbass187]

bump to see if slacker is still interested or if anyone else would like to take a crack at it.

[slacker]

sorry I'd completely forgotten about it, I'll see if I can do something this weekend.

[slacker]

Here's my attempt at a vero layout



Just realised I haven't added the pot values to it, I'll fix that.
I changed some of the odd component values on the schematic to the nearest standard ones, the actual schematic values are shown in brackets.
I'm not exactly sure how big the inductors are but hopefully there's enough room on the layout for them. I also saw in one of the other threads about this that some people had to use 3 100mH inductors instead of 2 150mH ones, there should be enough room to squeeze and extra inductor in there if you need to.

[slacker]

Found a couple of errors in the layout, I've fixed them and added the pot values. Hit refresh to make sure you've got the latest version or go to my gallery and get it from there.
http://aronnelson.com/gallery/slackers-stuff

[funkbass187]

thank you so much for that! hopefully by next week I'll have the components and can get working on that. thanks again

[slacker]

happy to help  Let me know how it works out.
Arrggh just noticed there should be a trace cut on the 3rd row down between the bottom of C7 and the top of R10.

[funkbass187]

VERIFIED! ~i built the circuit 3 or 4 months ago and made a stupid mistake wiring the jacks. i got busy and completely forgot about it until today. works great, and i'm taking it to the studio next week when I'm recording with my band so I'll have some sound clips   .