The Sushi Box FX Secret Society

[Rodrigo Silva]

Fine, I'll go ahead and spoil the surprise It's a hand-wired Space Heater. I was having a talk wioth one of my friends this morning and mentioned how cool it is that people enjoy the Space Heater so much, so figured it would be a good candidate for the hand-wired treatment. It's a simpler circuit than Underground Accelerator, so I should be able to do it for a little less this time.

Noob question. Why would I want it to be hand-wired? I imagine it sounds better, but how?

 

[moon-bass]

Psyched!!! Ordered.
View attachment 4405991

I think Red Penguin would be a great name for a pedal.

 

[Lowendtech]

Psyched!!! Ordered.
View attachment 4405991

I was so close to landing one of those. Congrats.

 

[Pedalnetics]

Psyched!!! Ordered.
View attachment 4405991

Lol, the eventual plan is we'll start documenting the pedals-in-progress, along with a way to sign up with notifications when it's ready for ordering

 

[Pedalnetics]

Noob question. Why would I want it to be hand-wired? I imagine it sounds better, but how?

Photo of the hand-wired UA. Ignore the details in this post, they were for another question about the UA in general:
The Sushi Box FX Secret Society
A tiny bit more detail here:
The Sushi Box FX Secret Society

Basically the bigger parts result in being able to run the tube at higher voltages, which is supposed to sound fuller/thicker/whatever-you-choice-good-phrase-is.

But, it's a lot more work physically, more time consuming, and more expensive overall for Sushi to do, so they're small batch limited edition runs

I haven't heard one myself compared to a regular, but I have no reason to doubt what others hear

 

[Rodrigo Silva]

Photo of the hand-wired UA. Ignore the details in this post, they were for another question about the UA in general:
The Sushi Box FX Secret Society
A tiny bit more detail here:
The Sushi Box FX Secret Society

Basically the bigger parts result in being able to run the tube at higher voltages, which is supposed to sound fuller/thicker/whatever-you-choice-good-phrase-is.

But, it's a lot more work physically, more time consuming, and more expensive overall for Sushi to do, so they're small batch limited edition runs

I haven't heard one myself compared to a regular, but I have no reason to doubt what others hear

Oh I see, higher voltages. That makes sense, thank you!

 

[Sushi Box FX]

Noob question. Why would I want it to be hand-wired? I imagine it sounds better, but how?

Aside from the higher voltage (not to downplay the higher voltage, that's a huge deal), there's also carbon comp resistors instead if metal film resistors. Carbon comp are common in boutique amps and preamps because of the way they fluctuate value based on voltage and current passing through them, so they "sag" at high voltages, whereas metal film resistors are more "stiff".

Also I use polyester film caps in the signal path, whereas my typical pedals use MLCC. There's subtleties there that I won't get into on those as it's a big debate between audiophiles and mass produced electronics, but even where the capacitance is the same the different dielectric will result in a different inductance, so just another factor in the tonal character.

From a reliability standpoint I really like them as well, since the caps are "self-healing," so if a voltage surge shorts the cap (shouldn't ever happen, but if) then the cap isn't ruined. MLCC if it shorts then it's dead and you swap it out.

So why don't I use film caps and carbon comp resistors on all my pedals?

1) way more expensive
2) way more labor intensive
3) way bigger; I'm a lot more limited as to what circuits I can fit in the boxes

 

[Rodrigo Silva]

Aside from the higher voltage (not to downplay the higher voltage, that's a huge deal), there's also carbon comp resistors instead if metal film resistors. Carbon comp are common in boutique amps and preamps because of the way they fluctuate value based on voltage and current passing through them, so they "sag" at high voltages, whereas metal film resistors are more "stiff".

Also I use polyester film caps in the signal path, whereas my typical pedals use MLCC. There's subtleties there that I won't get into on those as it's a big debate between audiophiles and mass produced electronics, but even where the capacitance is the same the different dielectric will result in a different inductance, so just another factor in the tonal character.

From a reliability standpoint I really like them as well, since the caps are "self-healing," so if a voltage surge shorts the cap (shouldn't ever happen, but if) then the cap isn't ruined. MLCC if it shorts then it's dead and you swap it out.

So why don't I use film caps and carbon comp resistors on all my pedals?

1) way more expensive
2) way more labor intensive
3) way bigger; I'm a lot more limited as to what circuits I can fit in the boxes

Thank you for the detailed explanation!

 

[cusar5]

Space Heater arrived! It's much smaller and lighter than I anticipated, and I'm very impressed with the build quality.

It has an insane amount of volume on tap, so the internal attenuator trimpot is a great feature. 9v and 12v both sound good, but I feel like there's a bit more definition on the low B at 12v, so that's probably what I'll stick with.

 

[Moody Tuner]

I just ran through everything with @Sushi Box FX, tested Paypal + all the new-site stuff (My Account stuff, streamlined-shipping, etc), and all is still happy with Paypal.

So, we'll leave both enabled, no extra fees anywhere, and ya'll can pay however you want: Google Pay, Apple Pay, CC direct on the site (and you can save cards on the site for future purchases, it is all handled by Stripe and fully PCI compliant storage/etc; payment security is part of my day-job ), or any-of-the-Paypal-options.

So buy away

Everyone loves SAQ-A!

 

[Sushi Box FX]

9v and 12v both sound good, but I feel like there's a bit more definition on the low B at 12v, so that's probably what I'll stick with.

There really shouldn't be any difference, the high voltage supplied to the tube is the same regardless of supply voltage. The only difference will be that the tube will heat up a little more, but at 9V it's already heating up enough to pass the full signal.

Glad you're enjoying it

 

[Pedalnetics]

Everyone loves SAQ-A!

Compared to dealing with Level 1 certification yearly, SAQ-A is amazing.

 

[bassbrad]

@Sushi Box FX would it be correct to describe Finally as a Space Heater that is also a Tube Direct Box?

 

[Sushi Box FX]

@Sushi Box FX would it be correct to describe Finally as a Space Heater that is also a Tube Direct Box?

Yup, 100% accurate description. I don't have the schematic in front of me right now but I can't distinctly think of anything I would have changed in the circuit. So take a Space Heater and add an $80 DI transformer, an XLR out and a couple toggle switches and you have Finally.

 

[JackFawkes]

I was listening to some Slampegg samples on sushiboxfx.com and I noticed the tube starting to breakup with gain at 12:00. Is this because the pedal was using 9v? Will I have more clean headroom at 12v? Could I possibly switch to a different tube to achieve this?

I'm late to the party (longtime Secret Society reader, first time poster) but I don't think anyone answered the last part of your question:
Theoretically, running a 5751 instead of a 12AX7 should let you turn up the Gain dial a few more notches before tube breakup while maintaining more or less the same tone overall.

Jack

P.S.: There are a bunch of other little details/theories/rules-of-thumb when it comes to swapping 12AX7; but to keep it simple, my understanding of one of them is that certain tubes are better for amplifying voltage in an audio circuit (12AX7, 5751, 12AY7) and others are better for amplifying current (12AT7, 12AV7, 12AU7).
So if you're swapping a 12AX7 (without changing any other components/bias in the circuit), you'll usually get best results from a 5751 or 12AY7... or so the Germans would have us believe.

 

[cusar5]

I'm late to the party (longtime Secret Society reader, first time poster) but I don't think anyone answered the last part of your question:
Theoretically, running a 5751 instead of a 12AX7 should let you turn up the Gain dial a few more notches before tube breakup while maintaining more or less the same tone overall.

Jack

P.S.: There are a bunch of other little details/theories/rules-of-thumb when it comes to swapping 12AX7; but to keep it simple, my understanding of one of them is that certain tubes are better for amplifying voltage in an audio circuit (12AX7, 5751, 12AY7) and others are better for amplifying current (12AT7, 12AV7, 12AU7).
So if you're swapping a 12AX7 (without changing any other components/bias in the circuit), you'll usually get best results from a 5751 or 12AY7... or so the Germans would have us believe.

So I should be able to swap a 5751 into the Space Heater as well?

Has anyone tried swapping tubes before? Any tips on how to get the tube in/out? I doubt I'll be trying it anytime soon, but I am curious.

 

[Pedalnetics]

Yup, 100% accurate description. I don't have the schematic in front of me right now but I can't distinctly think of anything I would have changed in the circuit. So take a Space Heater and add an $80 DI transformer, an XLR out and a couple toggle switches and you have Finally.

So I should be able to swap a 5751 into the Space Heater as well?

Has anyone tried swapping tubes before? Any tips on how to get the tube in/out? I doubt I'll be trying it anytime soon, but I am curious.

I swapped a 5751 into my SH, and it lost all growl and became a nice clean tube boost. I liked that usage for some things so much, I'm thinking I'll get a second SH so I don't have to tube swap.

Seems the common suggestion is a rubber band. I use a jewelers flat sxrewdriver and gently slowly pry it up on multiple sides little by little.

 

[Sushi Box FX]

So I should be able to swap a 5751 into the Space Heater as well?

Has anyone tried swapping tubes before? Any tips on how to get the tube in/out? I doubt I'll be trying it anytime soon, but I am curious.

Yup, I've had a couple people tell me they tried 5751 in Space Heater and really liked it. One of these days I'll get around to making a video to show how I get tubes in and out, I have a lot of practice Here's my basic method:

TUBE REMOVAL

1. Hold the pedal securely with both hands, right hand toward the top and left toward the bottom
2. pinch the top of the tube with your right thumb and index finger
3. place your left thumb near the base of the tube
4. wiggle the tube gently back and forth with your right thumb and index finger while pressing gently upwards with your left thumb

NEW TUBE INSTALLATION

1. Locate the gap between pins 1 and 9 on your tube
2. Holding the tube at an angle toward yourself, line up the tube with the socket, aligning pins 1 and 9
3. Insert pins 1 and 9 JUST A LITTLE BIT to keep alignment
4. Using your left thumb and index finger, gently push the tube backwards while pushing gently down on the top of the tube with your right thumb

Maybe I'll make videos of these processes and post them with these instructions in the FAQ on the website. One of the big reasons I moved away from the mini tubes was to let people change tubes themselves, so any 12A*7 family tube will work (except in Westinghouse).

P.S.: There are a bunch of other little details/theories/rules-of-thumb when it comes to swapping 12AX7;

Two of the biggest specs to look at when designing around preamp tubes is gain factor (mu) and plate current. 12AX7 has a high gain factor and a low plate current, 12AT7 has a medium gain factor and medium plate current, and 12AU7 has a low gain factor and high plate current.

Gain factor is obviously how much gain the tube will have. If you've ever swapped a 12AX7 out with a 12AT7 or 12AU7 in an amp you'll notice an immediate drop in gain. 12AX7 has a mu of 100, 12AT7 is 60, and 12AU7 is 20.

Plate current is the tube's ability to drive a load. How big of a load does a preamp need to drive? Almost none! That's what makes 12AX7 ideal, you can get all the gain you want, and the fact that it can't drive a load is irrelevant. There are a variety of 1W tube amps on the market these days, and most use 12AU7 as the power tube. "But 12AU7 is a low gain preamp tube, how can it drive a speaker?" It doesn't need gain to drive a load, it needs plate current! And 12AU7 has plenty of that on tap. If you put a 12AX7 in place of the 12AU7 in a 1W amp you would lose about 90% of your power. But things like low-impedance buffers and reverb drivers are excellent places for high plate current tubes, which is why Vampire Slayer uses 12AU7. "Tone suck" is a common term used for describing what happens when you're loading the output of a device. A buffer's job is to provide enough current to drive whatever load is being presented, be it a 100' cable or a passive tone stack.

Join us next week for another episode of Absurdly Long Answers to Simple Questions

 

[JackFawkes]

So I should be able to swap a 5751 into the Space Heater as well?

Yep.
Any of the common 9-pin dual-triode tubes can operate in the good Sushi-meister's masterpieces (excluding the Westinghouse).

And as far as my above postscript, you can still try a current amplifying tube like a 12T7 or 12AU7 in a 12AX7 circuit; rule-of-thumb just suggests that a 5751 or 12AY7 will usually sound better... but try anyways and always trust your own ears most.

Jack

 

[NKBassman]

According to the completely unverified tube comparison chart I always refer to via Google image search (attached below), the audio frequency bandwidth varies wildly across the 12A_7 family as well. Refer to the BW column at the right side.

Based on this chart (and moreso on what I had available to choose from in the drawer), I decided to replace the 12AX7 in my SWR Interstellar Overdrive with a 12AU7 ages ago. I didn't really care for the stock gain character of that preamp, but loved the clean tube character. Replacing the 12AX7 with a much lower gain tube widened the available range of clean tones before it goes into breakup, rather than getting straight into raging OD past 9:00 on the dial. And the clean tone is crystal clear without any "tone suck" or sounding choked out at all. Given the fact that human hearing tops out at 20 kHz, a 12AY7 would probably work just as well in that respect, but at more than double the gain VS a 12AU7.

Disclaimer, I don't know what any of the other variables refer to, other than mu and BW.