Sunn Beta Bass preamp schematic

Tube or solid-state, this section goes to eleven!

Sunn Beta Bass preamp schematic

Postby arcaarca » 15 Feb 2015, 19:25

Hi everyone!
Hope the topic is in the right area.
I'm updating the ugly jpg schematic of this amp, now I've made only a "single channel" version, removing the electronic switch. Here's an eagle version with really dummy libraries (sorry, first works with this software!), but more readable than the old one,and (I hope) useful!
I'd like to put this preamp in a box, and if someone wants to help with the layout will be great!

Single Channel Schematic
http://s3.postimg.org/ada3tjr0h/Sunn_Beta_Bass_Single_Channel.png

Double Channel A/B Schematic
http://s4.postimg.org/rw46zwogr/Sunn_Beta_Bass_AB_Channel.png

For this message the author arcaarca has received thanks: 4
dune2k (18 Feb 2015, 18:59), guile31 (09 Jul 2015, 13:17), HENK (17 Feb 2015, 10:57), morain51 (17 Apr 2015, 10:09)
arcaarca
 
Posts: 15
Joined: 10 Oct 2009, 15:17
Has thanked: 28 times
Have thanks: 10 times

Re: Sunn Beta Bass preamp schematic

Postby jbgron » 15 Feb 2015, 23:51

I have one of these amps, let me know if I can assist.

For this message the author jbgron has received thanks:
guile31 (09 Jul 2015, 13:17)
jbgron
Breadboard Brother
 
Posts: 81
Joined: 16 Sep 2008, 01:03
Location: Melbourne, Australia
Has thanked: 18 times
Have thanks: 5 times

Re: Sunn Beta Bass preamp schematic

Postby arcaarca » 19 Feb 2015, 17:30

Hi jbgron,
I've seen only the service manual of these amp, found online, and the schematic should be correct. What I'd like to do is a sort of ABY switch (true bypass) instead the electronic switch of the amp, and put all in a stompbox or similar.
The IC of the amp are CD4069 and 4558, right?
I'm trying put all in a veroboard layout, but I'm slow and lazy, so I started with sharing the "simplified and readable" schem!!
Cheers!

For this message the author arcaarca has received thanks:
guile31 (09 Jul 2015, 13:17)
arcaarca
 
Posts: 15
Joined: 10 Oct 2009, 15:17
Has thanked: 28 times
Have thanks: 10 times

Re: Sunn Beta Bass preamp schematic

Postby ZombiCrow » 14 Apr 2015, 22:14

How difficult will this be to distill into a distortion pedal, would you say? Thank you!

For this message the author ZombiCrow has received thanks:
guile31 (09 Jul 2015, 13:17)
ZombiCrow
 
Posts: 6
Joined: 18 Jul 2010, 20:16
Has thanked: 2 times
Have thanks: 1 time

Re: Sunn Beta Bass preamp schematic

Postby grrrunge » 15 Apr 2015, 14:07

ZombiCrow wrote:How difficult will this be to distill into a distortion pedal, would you say? Thank you!

If you're handy with Eagle or similar pcb-cad software: Not that difficult.
If you're badass around vero or perfboard: Not that difficult.
Otherwise: Pretty hard.
A true believer in the magic of Sherwood Forest Pedal Pirates
---
New base of operations: http://www.knucklehead.dk

For this message the author grrrunge has received thanks:
guile31 (09 Jul 2015, 13:17)
User avatar
grrrunge
Diode Debunker
 
Posts: 745
Joined: 20 Mar 2010, 11:51
Location: Copenhagen, Denmark
Has thanked: 58 times
Have thanks: 200 times

Re: Sunn Beta Bass preamp schematic

Postby grrrunge » 15 Apr 2015, 14:39

Looks like a fun project! Here's the service manual schematic:
sunn_beta_bass.jpg
You do not have the required permissions to view the files attached to this post.
A true believer in the magic of Sherwood Forest Pedal Pirates
---
New base of operations: http://www.knucklehead.dk

For this message the author grrrunge has received thanks: 2
Blitz Krieg (17 Mar 2016, 07:12), guile31 (09 Jul 2015, 13:17)
User avatar
grrrunge
Diode Debunker
 
Posts: 745
Joined: 20 Mar 2010, 11:51
Location: Copenhagen, Denmark
Has thanked: 58 times
Have thanks: 200 times

Re: Sunn Beta Bass preamp schematic

Postby morain51 » 15 Apr 2015, 16:18

Hi ! Please excuse my bad English because I'm French.
It seems like two resistors have been forgotten on the first post schematics.
R123 100k on channel 1, should be placed between lug 2-1 of Drive pot (R5/2 1M lin), and lug 1 of IC2A 4069N
= R152 100k on channel 2, should be placed between lug 2-1 of Drive pot (R40/2 1M lin), and lug 1 of IC7A 4069N

R186 1,5k on channel 1, should be placed between lug 7 of IC4B LM4558N and between the ends of R26 and C20
= R170 1,5k on channel 2, should be placed between lug 7 of IC9B LM4558N and between the ends of R61 and C42

There is a mistake on the Single Channel Schematic: it is mentioned that IC2 pin 8 is joined to +15V and IC2 pin 4 is joined to -15V. But it should be IC3 pin 8 and 4.
This mistake is not repeated on Double Channel A/B Schematic.

And lastly, C20, C21, C42 and C43 should have been reported as Non-Polarized: NP

I hope my post is understandable :)

For this message the author morain51 has received thanks: 2
arcaarca (28 Apr 2015, 17:25), guile31 (09 Jul 2015, 13:17)
morain51
 
Posts: 16
Joined: 01 Apr 2013, 22:51
Has thanked: 4 times
Have thanks: 23 times

Re: Sunn Beta Bass preamp schematic

Postby grrrunge » 15 Apr 2015, 18:29

Mind giving this a lookover, before i begin layouting?
sunn_beta_bass_preamp.png
You do not have the required permissions to view the files attached to this post.
A true believer in the magic of Sherwood Forest Pedal Pirates
---
New base of operations: http://www.knucklehead.dk

For this message the author grrrunge has received thanks: 3
arcaarca (28 Apr 2015, 17:24), deafbutpicky (15 Aug 2015, 18:46), guile31 (09 Jul 2015, 13:18)
User avatar
grrrunge
Diode Debunker
 
Posts: 745
Joined: 20 Mar 2010, 11:51
Location: Copenhagen, Denmark
Has thanked: 58 times
Have thanks: 200 times

Re: Sunn Beta Bass preamp schematic

Postby morain51 » 16 Apr 2015, 22:14

I think this one is correct,
I don't know how CD4049UBE should be powered, but on the original schematic 74C04 is powered with +8V
Why don't you use 4069 instead ?
Maybe you should indicate +V is +15V and -V is -15V

The volume pot is not wired as the Sunn schematic, but I don't know if it's important.

For this message the author morain51 has received thanks:
guile31 (09 Jul 2015, 13:18)
morain51
 
Posts: 16
Joined: 01 Apr 2013, 22:51
Has thanked: 4 times
Have thanks: 23 times

Re: Sunn Beta Bass preamp schematic

Postby deltafred » 16 Apr 2015, 23:20

morain51 wrote:I think this one is correct,
I don't know how CD4049UBE should be powered, but on the original schematic 74C04 is powered with +8V
Why don't you use 4069 instead ?
Maybe you should indicate +V is +15V and -V is -15V

The volume pot is not wired as the Sunn schematic, but I don't know if it's important.

4000 Series CMOS is limited to a supply voltage of 15v, how you are proposing connecting it would supply it with 30V.

It is usual, but not mandatory, to connected it between 0V and +15V supplies on a -15/0/+15 supply.
Politics is the art of so plucking the goose as to obtain the most feathers with the least squawking. - R.G. 2011
Jeez, she's an ugly bastard, she makes my socks hurt. I hope it's no ones missus here. - Ice-9 2012

For this message the author deltafred has received thanks:
guile31 (09 Jul 2015, 13:18)
User avatar
deltafred
Opamp Operator
 
Posts: 1377
Joined: 06 Apr 2010, 17:16
Location: Yorkshire, England, UK
Has thanked: 296 times
Have thanks: 238 times

Re: Sunn Beta Bass preamp schematic

Postby morain51 » 16 Apr 2015, 23:47

Sorry, I meant just specify that the circuit is powered with -15/0/+15 on your schematic (not especially the CMOS),
on the top left with the connecting points or in the indications at the bottom right.

If the CMOS can be powered with 0/+15V so you're right, let's skip the +8V :wink:

For this message the author morain51 has received thanks:
guile31 (09 Jul 2015, 13:18)
morain51
 
Posts: 16
Joined: 01 Apr 2013, 22:51
Has thanked: 4 times
Have thanks: 23 times

Re: Sunn Beta Bass preamp schematic

Postby grrrunge » 17 Apr 2015, 09:42

morain51 wrote:Why don't you use 4069 instead ?

That's a typo. The schematic should say CD4069UBE. My bad ;)

morain51 wrote:on the original schematic 74C04 is powered with +8V

The service manual is a little blurry, but the way i see it, the VCC-pin is connected to +15V through a 470R, and then there's a test point that should read +8V directly at the VCC-pin.
Connecting it to both a 15V and an 8V supply makes absolutely no sense, whereas a 7V voltage drop across 470R implies a current draw from the 4069 of roughly 15mA. That seems plausible.

morain51 wrote:Maybe you should indicate +V is +15V and -V is -15V

The plan is that this thing is going in a pedal. The most obvious solution would be to supply the circuit +/-9V from a 9V charge pump.

morain51 wrote:The volume pot is not wired as the Sunn schematic, but I don't know if it's important.

I think you're right. It's wired backwards in my schematic. Considering this is an inverting amplifier, the gain should rise as more resistance is introduced in the feedback path.
A true believer in the magic of Sherwood Forest Pedal Pirates
---
New base of operations: http://www.knucklehead.dk

For this message the author grrrunge has received thanks: 3
guile31 (09 Jul 2015, 13:18), HENK (18 Apr 2015, 11:54), morain51 (17 Apr 2015, 10:09)
User avatar
grrrunge
Diode Debunker
 
Posts: 745
Joined: 20 Mar 2010, 11:51
Location: Copenhagen, Denmark
Has thanked: 58 times
Have thanks: 200 times

Re: Sunn Beta Bass preamp schematic

Postby morain51 » 17 Apr 2015, 10:20

grrrunge wrote:The service manual is a little blurry, but the way i see it, the VCC-pin is connected to +15V through a 470R, and then there's a test point that should read +8V directly at the VCC-pin.
Connecting it to both a 15V and an 8V supply makes absolutely no sense, whereas a 7V voltage drop across 470R implies a current draw from the 4069 of roughly 15mA. That seems plausible.


You are certainly right, on Sunn manual the +8V is drawn with a circle instead of an arrow like the -15/+15V, it may be a test point.

So, this schematic is ready to being layout :thumbsup
Are you planning to edit a pcb board, or a veroboard ?

For this message the author morain51 has received thanks: 2
guile31 (09 Jul 2015, 13:18), HENK (18 Apr 2015, 11:56)
morain51
 
Posts: 16
Joined: 01 Apr 2013, 22:51
Has thanked: 4 times
Have thanks: 23 times

Re: Sunn Beta Bass preamp schematic

Postby grrrunge » 17 Apr 2015, 11:56

grrrunge wrote:
morain51 wrote:The volume pot is not wired as the Sunn schematic, but I don't know if it's important.

I think you're right. It's wired backwards in my schematic. Considering this is an inverting amplifier, the gain should rise as more resistance is introduced in the feedback path.

Just to correct myself: It looks like my drawing is correct. Look at the pot numbering and the direction indicating arrow ;)
A true believer in the magic of Sherwood Forest Pedal Pirates
---
New base of operations: http://www.knucklehead.dk

For this message the author grrrunge has received thanks: 2
guile31 (09 Jul 2015, 13:20), HENK (18 Apr 2015, 11:55)
User avatar
grrrunge
Diode Debunker
 
Posts: 745
Joined: 20 Mar 2010, 11:51
Location: Copenhagen, Denmark
Has thanked: 58 times
Have thanks: 200 times

Re: Sunn Beta Bass preamp schematic

Postby morain51 » 17 Apr 2015, 13:29

I admit I'm a bit lost with pot numbering. Fortunately, it is very easy to verify when plugging a pedal for the first time (and to correct mistakes :lol: )

Just in case, if you want to build a Beta Lead version, you will have to swap the following values in your schematic :
C15 : replace 56n by 22n
C17 : replace 8n2 by 5n
C18 : replace 15n by 8n2
C21 : replace 47n by 27n

I think these are the only differences between the two preamps.

For this message the author morain51 has received thanks: 2
guile31 (09 Jul 2015, 13:20), HENK (18 Apr 2015, 11:56)
morain51
 
Posts: 16
Joined: 01 Apr 2013, 22:51
Has thanked: 4 times
Have thanks: 23 times

Re: Sunn Beta Bass preamp schematic

Postby guile31 » 09 Jul 2015, 13:06

Hi guys,
thanks all for the job on this thread :thumbsup

i have the "service manual" and want to make a "lead" version of the grrrunge schem'
so, i'm a bit lost ....
not on the rez/caps values difference but on the IC's
why replace the rc4558 to 4opa ?
is the sound already "legit" with these replacements ?

if anybody have succesfully built one, can you please tell me what IC's u utilised (ref.) and if the grrrunge schem is working?
guile31
 
Posts: 11
Joined: 09 Jul 2015, 03:24
Has thanked: 24 times
Have thanks: 1 time

Re: Sunn Beta Bass preamp schematic

Postby grrrunge » 10 Jul 2015, 17:01

The 4OPA designation is for my own reference only, as the board layout I'm working on uses quad op-amps. 4558 will work fine in this circuit, as will any other general purpose op-amp ;)
A true believer in the magic of Sherwood Forest Pedal Pirates
---
New base of operations: http://www.knucklehead.dk

For this message the author grrrunge has received thanks:
guile31 (10 Jul 2015, 18:18)
User avatar
grrrunge
Diode Debunker
 
Posts: 745
Joined: 20 Mar 2010, 11:51
Location: Copenhagen, Denmark
Has thanked: 58 times
Have thanks: 200 times

Re: Sunn Beta Bass preamp schematic

Postby guile31 » 10 Jul 2015, 17:07

Ok, i understand
Thank you grrrunge :wink:
guile31
 
Posts: 11
Joined: 09 Jul 2015, 03:24
Has thanked: 24 times
Have thanks: 1 time

Re: Sunn Beta Bass preamp schematic

Postby HENK » 15 Aug 2015, 09:24

Morning.
Any News on this???
HENK
 
Posts: 40
Joined: 05 Sep 2008, 18:15
Has thanked: 216 times
Have thanks: 5 times

Re: Sunn Beta Bass preamp schematic

Postby grrrunge » 16 Aug 2015, 13:06

Nope. I haven't had the time recently. Exam preparations and studio-building is what i do most these days.
I'll get around to it eventually ;)
A true believer in the magic of Sherwood Forest Pedal Pirates
---
New base of operations: http://www.knucklehead.dk

For this message the author grrrunge has received thanks:
HENK (17 Aug 2015, 10:37)
User avatar
grrrunge
Diode Debunker
 
Posts: 745
Joined: 20 Mar 2010, 11:51
Location: Copenhagen, Denmark
Has thanked: 58 times
Have thanks: 200 times

Next

Return to Amplifiers

Who is online

Users browsing this forum: andreok and 2 guests