Red Llama Mk.II gut shots.

General documentation, gut shot, schematic links, ongoing circuit tracing, deep thoughts ... all about boutique stompboxes.
User avatar
The Rotagilla
Diode Debunker
Information
Posts: 744
Joined: 20 Aug 2007, 18:24
Has thanked: 7 times
Been thanked: 61 times

Post by The Rotagilla »

I wouldn't have bothered but this thing is noticeably quieter at idle than other Llama layouts I've built. The IC is a MC14049UBCP and all the resistors appear to be standard Llama value except for the circled one which if I'm reading the color bands correctly is a 15k or 16k but measures out at 74.8k (it's also late here and I've had a shitty day so the margin for error is pretty large). Anyway, I'm curious if anyone has thoughts as to why the new one is so much quieter. Enjoy.

Image Image

Image Image
The television will not be revolutionized.

User avatar
Duckman
Opamp Operator
Information
Posts: 1492
Joined: 20 May 2009, 01:45
Has thanked: 320 times
Been thanked: 134 times

Post by Duckman »

Wich one is the circled one? :lol:

User avatar
Steven_M
Resistor Ronker
Information
Posts: 386
Joined: 06 Jul 2009, 19:50
Has thanked: 59 times
Been thanked: 35 times

Post by Steven_M »

I wonder why they chose to use half watt resistors and those huge axial caps.

Maybe the metal film resistors really reduce the noise. I've only ever used carbon comp in my Llama build, and didn't notice it being particularly noisy. I used the tonepad layout.

User avatar
The Rotagilla
Diode Debunker
Information
Posts: 744
Joined: 20 Aug 2007, 18:24
Has thanked: 7 times
Been thanked: 61 times

Post by The Rotagilla »

Steven_M wrote:I wonder why they chose to use half watt resistors and those huge axial caps.

Maybe the metal film resistors really reduce the noise. I've only ever used carbon comp in my Llama build, and didn't notice it being particularly noisy. I used the tonepad layout.
Mojo of course! I've used various layouts and there's always been a fair amount of hiss/white noise (even with metal films) at idle with the Llama and like I said, this one is noticeably quieter. The 4049 seems to be wired up a little differently than what I'm used to seeing but I know they can be wired different ways to achieve the same end result. I suck at tracing so if anyone wants to take a crack at it, be my guest.
Last edited by The Rotagilla on 15 Mar 2012, 17:17, edited 2 times in total.
The television will not be revolutionized.

User avatar
The Rotagilla
Diode Debunker
Information
Posts: 744
Joined: 20 Aug 2007, 18:24
Has thanked: 7 times
Been thanked: 61 times

Post by The Rotagilla »

Duckman wrote:Wich one is the circled one? :lol:
OP edited. :D
The television will not be revolutionized.

User avatar
Güero 2.0
Breadboard Brother
Information
Posts: 82
Joined: 26 May 2008, 15:42
Has thanked: 3 times
Been thanked: 24 times

Post by Güero 2.0 »

Are the unused 4049 pins grounded?
I can't see from the pics.
"Come squeeze and suck the day.Come Carpe Diem baby!"

User avatar
The Rotagilla
Diode Debunker
Information
Posts: 744
Joined: 20 Aug 2007, 18:24
Has thanked: 7 times
Been thanked: 61 times

Post by The Rotagilla »

Güero 2.0 wrote:Are the unused 4049 pins grounded?
I can't see from the pics.
I appears they are running to a ground plane, yes. Same plane as the negtive side of the 100uf is connected to.
The television will not be revolutionized.

User avatar
Duckman
Opamp Operator
Information
Posts: 1492
Joined: 20 May 2009, 01:45
Has thanked: 320 times
Been thanked: 134 times

Post by Duckman »

Not perfect, but may be it helps
Attachments
RL MIRROR.jpg
RL MIRROR.jpg (39.39 KiB) Viewed 4326 times

User avatar
The Rotagilla
Diode Debunker
Information
Posts: 744
Joined: 20 Aug 2007, 18:24
Has thanked: 7 times
Been thanked: 61 times

Post by The Rotagilla »

The mystery resistor is a 75k, just needed some good light to see it. :D
The television will not be revolutionized.

User avatar
ppluis0
Diode Debunker
Information
Posts: 915
Joined: 14 Jul 2010, 18:33
Location: Argentina
Has thanked: 127 times
Been thanked: 299 times

Post by ppluis0 »

This revision use extensively ground planes at each side of the board, hence their resultant quietness, I think. 8)

Cheers,
Jose

User avatar
Duckman
Opamp Operator
Information
Posts: 1492
Joined: 20 May 2009, 01:45
Has thanked: 320 times
Been thanked: 134 times

Post by Duckman »

Seems like this to me (for a start) Pins 7, 9, 11 and 14 are not grounded
WHRL.doc
(33 KiB) Downloaded 327 times

User avatar
Duckman
Opamp Operator
Information
Posts: 1492
Joined: 20 May 2009, 01:45
Has thanked: 320 times
Been thanked: 134 times

Post by Duckman »

Hey Rotagilla, can you post the values for C3, 4, 5 & 6? Just to complete the picture.

User avatar
madbean
Information

Post by madbean »

Duckman wrote:Seems like this to me (for a start) Pins 7, 9, 11 and 14 are not grounded
WHRL.doc

I agree. It looks like they are tied to 9v.

User avatar
Duckman
Opamp Operator
Information
Posts: 1492
Joined: 20 May 2009, 01:45
Has thanked: 320 times
Been thanked: 134 times

Post by Duckman »

madbean wrote:
Duckman wrote:Seems like this to me (for a start) Pins 7, 9, 11 and 14 are not grounded
WHRL.doc

I agree. It looks like they are tied to 9v.
Is that a better way to get rid of the unused OA's?

User avatar
The Rotagilla
Diode Debunker
Information
Posts: 744
Joined: 20 Aug 2007, 18:24
Has thanked: 7 times
Been thanked: 61 times

Post by The Rotagilla »

Duckman wrote:Hey Rotagilla, can you post the values for C3, 4, 5 & 6? Just to complete the picture.
I am assuming C3 = 51pf and C4 = 100pf as in the original. C5 = 100uf and C6 = 10uf tantalum.
The television will not be revolutionized.

User avatar
Duckman
Opamp Operator
Information
Posts: 1492
Joined: 20 May 2009, 01:45
Has thanked: 320 times
Been thanked: 134 times

Post by Duckman »

The Rotagilla wrote:
Duckman wrote:Hey Rotagilla, can you post the values for C3, 4, 5 & 6? Just to complete the picture.
I am assuming C3 = 51pf and C4 = 100pf as in the original. C5 = 100uf and C6 = 10uf tantalum.
Ok, that's nice. But, since the unit has some custom tracing, can you confirm it?... please? :oops:

User avatar
The Rotagilla
Diode Debunker
Information
Posts: 744
Joined: 20 Aug 2007, 18:24
Has thanked: 7 times
Been thanked: 61 times

Post by The Rotagilla »

Duckman wrote:
The Rotagilla wrote:
Duckman wrote:Hey Rotagilla, can you post the values for C3, 4, 5 & 6? Just to complete the picture.
I am assuming C3 = 51pf and C4 = 100pf as in the original. C5 = 100uf and C6 = 10uf tantalum.
Ok, that's nice. But, since the unit has some custom tracing, can you confirm it?... please? :oops:
All values have been confirmed.
The television will not be revolutionized.

User avatar
Groovenut
Resistor Ronker
Information
Posts: 299
Joined: 07 Jan 2011, 16:31
Has thanked: 60 times
Been thanked: 100 times

Post by Groovenut »

Duckman wrote:
madbean wrote:
Duckman wrote:Seems like this to me (for a start) Pins 7, 9, 11 and 14 are not grounded
WHRL.doc

I agree. It looks like they are tied to 9v.
Is that a better way to get rid of the unused OA's?
Depending on the circuit (ie the number of power connections) the filtered 9V rail can be considerable quieter than ground. Since it is a stable dc voltage, it has the same function as ground to signals.

User avatar
jonasx26
Breadboard Brother
Information
Posts: 118
Joined: 03 Jun 2009, 17:53
Location: Sweden
Has thanked: 84 times
Been thanked: 48 times
Contact:

Post by jonasx26 »

Is that a better way to get rid of the unused OA's?
Doesn't matter if you tie unused gates to ground or VCC.
The whole point of terminating the unused gates is to keep them at a fixed high/low-state.
Without a solid input signal the high impedance gates can pick up random noise and oscillate.

There MIGHT be a difference in whether you terminate them at VCC or ground within a certain pcb layout.
Look at the internal schematic of a 4049 inverter, see where the currents flow, and keep this in mind while designing the pcb..

User avatar
Liquids
Breadboard Brother
Information
Posts: 143
Joined: 24 Apr 2009, 19:29
my favorite amplifier: Ampeg V4!!!!
Location: USA
Has thanked: 20 times
Been thanked: 27 times

Post by Liquids »

jonasx26 wrote:
Is that a better way to get rid of the unused OA's?
Doesn't matter if you tie unused gates to ground or VCC.
The whole point of terminating the unused gates is to keep them at a fixed high/low-state.
Without a solid input signal the high impedance gates can pick up random noise and oscillate.

There MIGHT be a difference in whether you terminate them at VCC or ground within a certain pcb layout.
Look at the internal schematic of a 4049 inverter, see where the currents flow, and keep this in mind while designing the pcb..
You connect unused CMOS stage's inputs to one of the rails to reduce overall current draw, in addition to the above. Leave the output of an unused CMOS stage's output connected to nothing if unused.

V+ is rarely as stable a voltage as we'd like it to be or try to make it given signal transients - which in some cases are clipping rail to rail. Ground is usually (if everything is properly wired) a bit closer to stability and 'less prone to noise' (!)....ground has less current potential than any other voltage.

In the end, connecting the unused CMOS stages input to either rail or the other is far superior to leaving unused CMOS gates 'floating.'

Some familiar designs utilize bipolar (+/-) voltages, and the CMOS devices see ground as their V+ and a negative voltage on their 'most negative rail voltage' pin. I'd still go with utilizing ground as the best place to connect unused inputs in this case.

As a side note, I hope no one reading this assumes that best-practice is the same for an unused op amp stage: an unused op amp stage should be wired like a buffer (Connect output to negative input), and the non-inverting input is best tied to the CENTER point between the two rails - in a typical 9v pedal, that's VREF (4.5v) etc, in a bipolar configuration that is ground, etc. Or even better, use that op amp stage. Because while CMOS gates are often more plentiful, they are not as 'swiss army knife' as an op amp stage, which can do and improve many things in a circuit.

Post Reply