New Amplifier Design - "Murder One" - Submini Pentode, Low Voltage

[iccaros]

first to come to mind would be a 12au7 or 12ax7 for the 6111
I don't know what your link is showing for the 5672 as the picture looks like a EL34 or a 6L6 not  a 5672, but any small pentode could take its place, 6au6 for example

If its just sockets your are looking for

There were sockets for subminature tubes, but I find they go microphonic when they can move around, I suggest you just solder them. but here are some sockets http://dhost.info/mhdtlab/socket.htm

[gretsch61]

first to come to mind would be a 12au7 or 12ax7 for the 6111
I don't know what your link is showing for the 5672 as the picture looks like a EL34 or a 6L6 not  a 5672, but any small pentode could take its place, 6au6 for example

If its just sockets your are looking for

There were sockets for subminature tubes, but I find they go microphonic when they can move around, I suggest you just solder them. but here are some sockets http://dhost.info/mhdtlab/socket.htm

Thx for your quick reply! Will a 12au7 or 12ax7 (do they have 8-Pins? I think they have 9???) work with the Voltage supplied by this Layout?
The 5672 says its a subminiature pentode...
I would really like to use socket, cause I would do some cosmetic to the look of the Amp and
use something like this to protect
the tubes.

[gretsch61]

Nice. 6112 is like twice the gain of 6111. It will require higher anode resistors ( R1, R2 - try 100k) and probably a higher value grid stopper ( R12 - try 470k).

If it still motorboats after changing those value, try cutting the HV trace between C12 and R1/R2 and bridging the cut trace with a 22k resistor. For completeness, also consider adding another 10uF 100v cap between R1/R2 and ground. Basically, cutting the trace, bridging it with the resistor and adding the extra cap is creating a B1 (to the 5672's B+), really you're converting the preamp section to a Superfly preamp.

BTW, I've got a few spare etched PCBs and tube sets if anyone wants one.

I use 120 K Ohm for R1/R2 and 510K for R12, also applied C12 and 10 µF. The sound is much better, "motor boating" can be eliminated, if I crank it can be very cool. Now I come to the next problem, the sound is cutted earlier as I expect, i.e. if I pick string E Low, the "sustain" is stopped much earlier (even earlier than a Django style guitar). After picking a string the sustain makes hingher volume and suddenly (millisecond) niose and than stop. Any suggestion? Bad tube maybe ?
Regards

Hi Rick, hi Blackface,

would this be the right Layoutchange for the 6112-mod?
http://s7.directupload.net/file/d/2995/h8er95ir_gif.htm

cheers,

[iccaros]

first to come to mind would be a 12au7 or 12ax7 for the 6111
I don't know what your link is showing for the 5672 as the picture looks like a EL34 or a 6L6 not  a 5672, but any small pentode could take its place, 6au6 for example

If its just sockets your are looking for

There were sockets for subminature tubes, but I find they go microphonic when they can move around, I suggest you just solder them. but here are some sockets http://dhost.info/mhdtlab/socket.htm

Thx for your quick reply! Will a 12au7 or 12ax7 (do they have 8-Pins? I think they have 9???) work with the Voltage supplied by this Layout?
The 5672 says its a subminiature pentode...
I would really like to use socket, cause I would do some cosmetic to the look of the Amp and
use something like this to protect
the tubes.

they would work at these voltage, at about 80volts you get good reaction from the 12XX7 types..  I do like those protectors

[gretsch61]

they would work at these voltage, at about 80volts you get good reaction from the 12XX7 types..  I do like those protectors

okay, but how about the number of pins? would I have to do a redesign of the tubesection? The difference between the 6111 and the
12au7 is PIN9 which would be the "Heater Center tab". How would I have to modify the design of the MurderOne to fit the 12au7?

On the 6au6 its a little different! The 7 pins are:

1: Grid No.1                            
2: Grid No.3, Internal Shield      
3: Heater
4: Heater
5: Plate
6: Grid No.2
7: Cathode

while the 5672 Pentode (5 Pins) is like this:

1: Plate
2: Grid No.2
3: Filament (Heater), positive
4: Grid No.1
5: Filament (Heater), negative: Grid No.3

so we are missing out on the Internal Shield and the Cathode. Any Suggestions? 

[gretsch61]

Hi Everyone,

would it be possible to add a tonestack to the MurderOne?

E-D-I-T:

I have found a schematic, that would bring a Tonestack to the MurderOne:

This would do the Job...





thx for any help!

[Maik]

Hi,
I want a blender before the speaker out. It should not affect the preamp out.
http://tagboardeffects.blogspot.com/2012/02/split-n-blend.html#links

This is how I want it...
http://img198.imageshack.us/img198/2493/miniampblend.jpg

Where is the point to put the blend in?

[Maik]

Rick???

[Magnus]

Hello,
I am building the Murder One right now and I have a question:

The 6111-Tube starts with Pin 1 soldered to the quarter on the pcb,
then Pin 2, 3 and 4 are soldered from left to right next to the quarter
and Pin 5 starts above Pin 4, following Pin 6, 7 and 8 from right to left - correct?

...hope you understand my definition  


Greetings
Magnus

[frequencycentral]

Hello,
I am building the Murder One right now and I have a question:

The 6111-Tube starts with Pin 1 soldered to the quarter on the pcb,
then Pin 2, 3 and 4 are soldered from left to right next to the quarter
and Pin 5 starts above Pin 4, following Pin 6, 7 and 8 from right to left - correct?

...hope you understand my definition  


Greetings
Magnus

Correct, just like an 8 pin DIL.

[frequencycentral]

Hi,
I want a blender before the speaker out. It should not affect the preamp out.
http://tagboardeffects.blogspot.com/2012/02/split-n-blend.html#links

This is how I want it...
http://img198.imageshack.us/img198/2493/miniampblend.jpg

Where is the point to put the blend in?

I'd try between the two preamp stages. After C13, before the gain pot. Maybe.

[Magnus]

Thank you Rick,
yes 8 Pin DIL, why didn't I explain it this way - could be much easier

Today I got my 6111-Tube, now I'm waiting for the enclosure, wallwart and knobs...

...just can't wait to build and hear it 

So here's a picture of the finished "vintage-style" pcb:




Greetings
Magnus

[iccaros]

they would work at these voltage, at about 80volts you get good reaction from the 12XX7 types..  I do like those protectors

okay, but how about the number of pins? would I have to do a redesign of the tubesection? The difference between the 6111 and the
12au7 is PIN9 which would be the "Heater Center tab". How would I have to modify the design of the MurderOne to fit the 12au7?

On the 6au6 its a little different! The 7 pins are:

1: Grid No.1                            
2: Grid No.3, Internal Shield      
3: Heater
4: Heater
5: Plate
6: Grid No.2
7: Cathode

while the 5672 Pentode (5 Pins) is like this:

1: Plate
2: Grid No.2
3: Filament (Heater), positive
4: Grid No.1
5: Filament (Heater), negative: Grid No.3

so we are missing out on the Internal Shield and the Cathode. Any Suggestions? 

Sorry I took so long, I missed your reply.


With the miniature your right, the cathode is part of the heater,  but with  a non directly heated tube like 6au6 or the 12ax7 you have to add a resistor to ground for a bias, Rick has already done that with the 6111, which is a good starting point. But the pins are different, but if your using a socket that should be easy to change.

[tom42107]

So, I'm having some trouble with my MO.

http://www.diystompboxes.com/smfforum/index.php?topic=73222.msg859500#msg859500

Not sure how to describe it. When I take some voltage readings it seems to be stable with both knobs turned all the way down, but when I turn the knobs all the way up, it seems to become unstable. For instance, the voltage coming out of the charge pump is a stable ~75vdc, but when I turn the knobs up, it bounces from 73v to 81vdc, back and forth. I've swapped out the 7660s with a 1044 and it doesn't change. When I plug it up it just doesn't sound right. Here are some of the voltage readings I'm getting with the knobs  down and unplugged from speaker:

6111
Pin 1 - 38V
2 - 3.6mV
3 - 6.6V
4 - 1.23V
5 - 1.32V
6 - 5mV
7 - (-10mV)
8 - 34.7V

5672
Pin 1 - 64.5V
2 - 75.3V
3 - 1.61V
4 - 4.4mV
5 - 4.8mV

The 5672 never really gets hot, in fact, I can't really see it glow. Could it be bad? Thanks.

Tom

[tom42107]

Sorry, I should have mentioned that this is V7 with the switched pre out.

Tom

[iccaros]

Tom
do you get audio through?

your voltages look OK, at least workable, I do not remember what the plates on the 6111 should see.

Voltage will fluctuate as current is passed through the tube, as for
"he 5672 never really gets hot, in fact, I can't really see it glow. Could it be bad? "
no this is normal with this tube..

[tom42107]

iccaros, yes, It does pass audio. The problem may be I just don't have anything to compare it to. I feel that it doesn't sound right. Do I need to lift the 1/4in. jacks off the case with isolating washers? Thanks for your help.

Tom

[Magnus]

Hello,
I am building my Murder one (V7) now, but I don't know if I have done anything right on the offboard wiring...
The volume is a little bit low, so probably theres an error in my (ground-)wiring
or maybe it is ok for a small amp like that (connected to a 1x12 box), I don't know...

btw: The amp is running, but there is a big problem:
The IC, the non-polarized caps and some Electrolytics get really hot  

- Where do the ground connections from the pcb exactly go to and where do they meet?
(would be nice to explain it, I am not sure if I have done them all right)

- Do I have to connect the grounds from both jacks together and to the enclosure (they are isolated ones)?

So after much builds that worked at the first try it was time to get problems 


Greetings
Magnus

[bluebunny]

The IC, the non-polarized caps and some Electrolytics get really hot  

You might find that this is the 18R drop resistor for the first valve's heater.  Mine got incredibly hot and was heating up everything else close by.  I chickened-out and externalised mine to avoid a fire or a meltdown or something worse...

- Where do the ground connections from the pcb exactly go to and where do they meet?
(would be nice to explain it, I am not sure if I have done them all right)

- Do I have to connect the grounds from both jacks together and to the enclosure (they are isolated ones)?

Yep, join all the grounds together, including the output jack, and connect to the enclosure (perhaps via the input jack screen, or one of the bolts holding the OT).

[BurgerFactory]

Hi Guys,
I am new to this sight in registration only. I have built many projects with the help and genius of some threads from this sight. Yesterday I finished a version of Rick Holts Murder ONE. I used a 12AT7 for the Pre amp and a 5672 for power. A 7660 for the pump and some messing around and reconfiguring and the thing sounds amazing. I just wanted to say that this is a brilliantly simple and effective design and I can't thank Rick and all of you DIYSB members enough for posting all of the info you have on this and many other topics. I do Instrument amp repairs out of my house and have always wanted a low wattage tube project. I have been building my own effects for years but havn't tackled the amp world until now. Partially from sickness of looking at them all hacked to hell all the time lol, and mostly from lack of effort on my part to create a good design. Anyway blah blah blah I feel guilty for susing the s#$t out of this sight and not contributing so here I am and I will post some pics and clips of this little amp as soon as I can.

Cheers,
Troy