"Red Star Drive"

[morcey2]

You forgot one thing! 

Add a pot(100k-500k) between the 1µf cap and ground.  That way you can dial in compression from the pentode.  I didn't have the idea.  It's ripped off of the Blues Preamp from ax84.com.  It's usually a linear pot, but I've found that a reverse audio generally works better.

Matt

[frequencycentral]

Thanks Jimmy!

I think practically the layout and the schematic are functionally the same. The way the pot is wired in the layout is how I did my build. I should alter the schematic really - I get confused with pot lug numbers. I can't tell left from right either!

[frequencycentral]

You forgot one thing! 

Add a pot(100k-500k) between the 1µf cap and ground.  That way you can dial in compression from the pentode.  I didn't have the idea.  It's ripped off of the Blues Preamp from ax84.com.  It's usually a linear pot, but I've found that a reverse audio generally works better.

Matt

That sounds interesting......what does it do, how does it sound, and do you think it would work at low voltage? Do I need to breadboard this idea?

[Jimmy-H]

Ah now I see!!
It's different compared to the schematic, but it works just the same!

[morcey2]

That sounds interesting......what does it do, how does it sound, and do you think it would work at low voltage? Do I need to breadboard this idea?

I've got a couple of amps that use the pentode side of a 6U8 or 6GH8 as the first gain stage that has the 'squish' control in them.  It very much changes the feel of the amp and adds quite a bit of compression when it's dialed in all the way.  I ended up wiring my pots backwards on both amps so the knob is labeled 'dynamics'. 

The summary on what it does is vary the stiffness of the screen voltage.   With just the cap from screen to ground, the screen voltages is very stiff which allows the pentode to have it's full range of dynamics.   If you remove the cap totally, the screen voltage varies with the signal.  The larger the signal, more current the screen pulls which drops voltage through the resistor feeding the screen, the 100k in your schematic.   The pot varies the screen stiffness between these to extremes. 

'Zoe N Iain' over at ax84 are the ones that originated it over there, so they'll probably give you a much better description than me.

And yes, I think it would work at low voltage. And yes, you need to breadboard it.  You may need to drop the value of the cap to get the full range though. 

And yes, I need to order me some submini tubes.  You've come up with some seriously cool stuff.

Matt

[frequencycentral]

That sounds interesting......what does it do, how does it sound, and do you think it would work at low voltage? Do I need to breadboard this idea?

I've got a couple of amps that use the pentode side of a 6U8 or 6GH8 as the first gain stage that has the 'squish' control in them.  It very much changes the feel of the amp and adds quite a bit of compression when it's dialed in all the way.  I ended up wiring my pots backwards on both amps so the knob is labeled 'dynamics'. 

The summary on what it does is vary the stiffness of the screen voltage.   With just the cap from screen to ground, the screen voltages is very stiff which allows the pentode to have it's full range of dynamics.   If you remove the cap totally, the screen voltage varies with the signal.  The larger the signal, more current the screen pulls which drops voltage through the resistor feeding the screen, the 100k in your schematic.   The pot varies the screen stiffness between these to extremes. 

'Zoe N Iain' over at ax84 are the ones that originated it over there, so they'll probably give you a much better description than me.

And yes, I think it would work at low voltage. And yes, you need to breadboard it.  You may need to drop the value of the cap to get the full range though. 

And yes, I need to order me some submini tubes.  You've come up with some seriously cool stuff.

Matt

Thanks morcey/yecrom, that's a really interesting concept. I'm going to have to investigate this fully at some stage soon. I guess it will end up in another damned pedal build!

[Jimmy-H]

I guess it will end up in another damned pedal build!

TSS TSS TSS TSS

[morcey2]

I guess it will end up in another damned pedal build!

Hate it when that happens!!

[morcey2]

Rick,
Have you had a chance to try the squish control on one of these yet?   

Matt

[frequencycentral]

Rick,
Have you had a chance to try the squish control on one of these yet?   

Matt

Haven't tried it yet - though jasperoosthoek over at the AX84 forum is doing some interesting experiments with the PentaBoost/Red Star Drive, including adding a CCS instead of the anode resistor to get more gain - I suggested 'squish' to him. Hopefully something good will come out of that. I'll get onto it in a while - I've got another project on the breadboard right now though!

[sweetwilly]

I breadboarded a hybrid of Jasper's revision and the MKI this evening and played around with diode combos for a bit.  I found 2 1n67a's and a 1 1n4148 to suit.  Also changed the input cap to 0.0022 for the hell of it to see if it brightened up with both neck and bridge.  Didn't really make a huge difference straight into a USB mixer to my mac.  I used the extra PNP transistor stage from the Pentaboost MKII as I don't have all the parts for the full Red Star MKII but still found the results very pleasing.  Also tried the squish pot out. Seems to reduce gain a bit from my quick play, but only played around very quickly. 

Nice work again Rick and kudos to Jasper at AX84 also.

[frequencycentral]

Jasper Oosthoek over at AX84 has now finalised his redesign of my "Red Star Drive" and has also finished his pedal build. He's christened it "Decibel".

Here's Jasper's soundclip, the song was recorded with a telecaster equivalent for riff #1 and les paul type sound for riff #2 and solo. The clip/texture knob is either at 0% for riff #1 and at 100% for the rest.  : http://www.iivault.com/jasper/She%20just%20won't%20listen.mp3

And here's his schematic, the 'Clipping/Texture' pot is a dual-ganged Lin pot, which maintains the volume when increasing the clipping. In my MkI version increasing the clipping caused a decrease in volume.

[frequencycentral]

Hi Adriano,

Could I ask you check my vero layout please? I'm asking because a couple of people have PM'd me asking if it's verified, so I'd like to know that another set of eyes other that mine have checked it out. If you could look it over and bump the thread if you think the layout is cool I would be grateful. If you see mistakes please PM me.

Best wishes and thanks,

Rick

I didn't build it but seems ok to my eyes...
So yeah it should work correctly - Adriano

[stereovoid]

hey guys, hope all are well! does anyone know where i can source the diodes for this pedal? found one at maplin but the second i'm having no luck with! cheers!

[frequencycentral]

Hi Rick,

Sorry for the delay, but the Vero you made seems OK to me!
But you already have a new version so.......time for a new vero
I've been busy with all kind of stuff...sadly not with effect building!
But keep up with the good stuff you are doing'.

Best wishes to you to!

[svstee]

Question about V2.
I bought up a bunch of those subminis when I saw the thread over at AX84, but ran into some problems getting the 317's. I want to build one, but I don't have any 1 watt resistors. Can I use 1/2 watt resistors?

[frequencycentral]

Question about V2.
I bought up a bunch of those subminis when I saw the thread over at AX84, but ran into some problems getting the 317's. I want to build one, but I don't have any 1 watt resistors. Can I use 1/2 watt resistors?

Hi, nice to see this thread again, I do love the RSD for rhythm work. That 220 ohm/1 watt resistor drops the 12 volts supply down to 1.275 volts (which is the heater requirement). All that voltage that's being dropped has to go somewhere, and is dissipated as HEAT, so thats why the resistor is 1 watt - to handle the heat. If you were to use a 1/2 watt resistor you would risk it burning out, as it would be incapable of handling the dissipated heat. So to be safe you really need a 317 or the specified 220 ohm/1 watt resistor.

I'm not sure if it would be possible to parallel two 440 ohm/ 1/2 watt resistors? That would give you the correct voltage drop, but I don't know if paralleling two 1/2 watts gives a 1 watt. Anyone know?

If you have some 5672 spare you could try my "Murder One" amp - but hold off for a while as I'm still experimenting with different topologies.

Good luck with your build!

Rick

[svstee]

I've been following your murder 1 thread, it looks awesome, unfortunately I don't have any LM317's or the transformer. Once you get the final setup worked out, I'll get what I need, though.
I thought about two 1/2 watt 440's, but I'm not sure if that would give you 1 watt. I think you just get 1/2 watt 220, I'm not sure, though.

[svstee]

OK, I'm going to use two 1/2 watt 440ohm resistors and hope for the best.
Wish me luck!

[frequencycentral]

OK, I'm going to use two 1/2 watt 440ohm resistors and hope for the best.
Wish me luck!

Good luck! Hope it works out!