Henning Bottle Rocket Amp... UPDATED 1/22!

[Anonymous]

Hey guys,

Thought you might like to see some of what goes into designing one of my amps. I'll try and update this thread as the design proceeds if people are interested.

So... to review, here is what I'm going for:

50 watt power amp (EL34 based)
DC heaters
Single channel (customer chooses either my PLEX or ROD channel from the Cherry Bomb) and a single board can implement either design
Two footswitchable masters (Regular and Solo), each with 3 way saturation switch
Series/Parallel switchable Tube buffered EFX Loop with independent Send and Receive pots (can be footswitched in/out of the circuit)
New 3 way "Bright" switch
Replacing Density control with a Resonance control
External Bias points and adjustment
Overall Master (PPIMV)
No line out (I figure people can use the Suhr Iso Line out box if they need one)…
Price $1850-1999 (TBA, of course!)

The first thing I did was get the schematics done and then it is on to 3D mechanical design. 3D Models of each part are made (Including the new custom 50 watt transformers from Mercury Magnetics) and then the mechanical design can proceed. Here is where things are right now:

You can see the new bright switch in the front view:

Hookups for your multimeter for bias adjustment on the back:

In the top view, you can see the black cutouts in the chassis by each power tube socket for the bias adjust pots for each tube. You just put your screwdriver in the hole and the bias pot is right there. The new head shell design will make it easy to take the back panel off to get at these pots. At least you don't have to take the amp out of the chassis!

Now one of the things I wanted to do to reduce cost and simplify the builds was to PCB mount the power tubes (my preamp tubes have always been PCB mounted). Some people complain about PCB mounted tubes, but I think this approach will satisfy everyone. Below are some screenshots I captured from the 3D model to show how these will be done.

So, as you can see, the long leg Belkin socket is soldered to the (green) PCB and there is a hole cut in the PCB on each side of the socket. A 15mm standoff will be screwed to the PCB. When assembling the amp, the standoff comes up to the chassis as well and the standoff is screwed onto the chassis. This way, it is ROCK solid AND I can easily take out the board without having to unsolder the octal sockets. Pretty cool, huh? PCB AND chassis mounted. I'll still be using 1/8" thick boards, so this out to work well. I'll use metric screws and spilt washers on this. This design will allow me to use the same pcb to chassis spacing as the Cherry Bomb (same PEMs ~15.956mm).

BTW - those long Belkin octal socket legs will be trimmed after soldering. Not gonna leave all that leg on the PCB - we'll keep it neat.

Steve

 

[Badronald]

Very nice!
Do you have a time frame on production?
Head only? Rackmount?
Smaller head?
High gain? Vintage high gain?

 

[chumbucket]

Very cool.
That looks like a pretty robust solution for PCB mounted power tubes. Waiting for the next installment.

 

[Deleted member 10619]

External bias points

I'd love my Cherry Bomb even more if it had this feature!

I'd choose the ROD single channel, because it cleans up really nice with a decent guitar.

 

[FourT6and2]

Looks awesome!

The implications of the chassis mounting... with long PCB pins mean lots of extra work to service the amp. Not gonna go that route.

Why the change of heart? You seemed pretty adamant about not doing it that way. Or were you always planning to do it this way with the power tubes, but not the preamp?

 

[Anonymous]

Looks awesome!

The implications of the chassis mounting... with long PCB pins mean lots of extra work to service the amp. Not gonna go that route.

Why the change of heart? You seemed pretty adamant about not doing it that way. Or were you always planning to do it this way with the power tubes, but not the preamp?

I found a way to do it that made it possible and met my needs for ease of servicing. The key is the 15mm standoffs. Let me explain...

So think about it this way. The pins have to be soldered to the PCB on top and on bottom of the board, so they have to be soldered to the board first - you can't screw them into the chassis first. This also means they have to be mounted under the chassis, not on top. Given that, it is impossible to have enough room to get your fingers between the board and the chassis and far enough back to get a washer and nut over screws through the chassis and the octal sockets. Now you could have a threaded insert built into the chassis, but that wouldn't work either because the octal sockets would have to be mounted on top of the chassis to do that, which can't be done because the octal sockets have to be soldered to the board first... it would also add cost to have the chassis fabricated with threaded inserts...

So... the 15mm standoff, which is threaded completely through solved the problem. You screw the octal sockets to the PCB, solder them on both sides, trim the excess length of the legs and remove the top screw and split washer. Now when you're ready to insert the board, you simply screw in the octal sockets to the chassis from the top and the rest of the board to the PEMs. This was the only way I could think of to make it work to have the sockets screwed to the chassis, make it possible to remove the board without de-soldering the octal sockets and allow the sockets to be soldered on both sides of the PCB.

The long PCB pins are necessary to make this work, but the way you originally suggested wouldn't have worked for me for two reasons. One, you'd have to screw the sockets to the chassis first, so you can't solder them to both sides of the PCB, and two, you'd have to de-solder the pins anytime you remove the board because there would be no way to reach under the boards to unscrew the sockets. Now, as I said, you could do it with threaded inserts built into the board, but then the sockets would have to be top mounted, which is an issue for soldering both sides and adds cost...

Steve

 

[Anonymous]

Very nice!

Thanks man!

Do you have a time frame on production?

I hate to quote this stuff because everything always takes longer than you think it will, but I'm planning for the first production units in Q1 2015...

Head only? Rackmount?

Head and combo...

Smaller head?

The chassis will be only 20". 21.75" total including the head shell - much smaller footprint compared to the Cherry Bomb.

High gain? Vintage high gain?

You have a choice between my ROD (high gain) or PLEX (vintage high gain) channel. The board will accommodate either channel.

Steve

 

[rlord1974]

Cool stuff, Steve. I'm intrigued.

Bookmarked to follow the journey!

 

[FourT6and2]

Looks awesome!

The implications of the chassis mounting... with long PCB pins mean lots of extra work to service the amp. Not gonna go that route.

Why the change of heart? You seemed pretty adamant about not doing it that way. Or were you always planning to do it this way with the power tubes, but not the preamp?

I found a way to do it that made it possible and met my needs for ease of servicing. The key is the 15mm standoffs. Let me explain...

So think about it this way. The pins have to be soldered to the PCB on top and on bottom of the board, so they have to be soldered to the board first - you can't screw them into the chassis first. This also means they have to be mounted under the chassis, not on top. Given that, it is impossible to have enough room to get your fingers between the board and the chassis and far enough back to get a washer and nut over screws through the chassis and the octal sockets. Now you could have a threaded insert built into the chassis, but that wouldn't work either because the octal sockets would have to be mounted on top of the chassis to do that, which can't be done because the octal sockets have to be soldered to the board first... it would also add cost to have the chassis fabricated with threaded inserts...

So... the 15mm standoff, which is threaded completely through solved the problem. You screw the octal sockets to the PCB, solder them on both sides, trim the excess length of the legs and remove the top screw and split washer. Now when you're ready to insert the board, you simply screw in the octal sockets to the chassis from the top and the rest of the board to the PEMs. This was the only way I could think of to make it work to have the sockets screwed to the chassis, make it possible to remove the board without de-soldering the octal sockets and allow the sockets to be soldered on both sides of the PCB.

The long PCB pins are necessary to make this work, but the way you originally suggested wouldn't have worked for me for two reasons. One, you'd have to screw the sockets to the chassis first, so you can't solder them to both sides of the PCB, and two, you'd have to de-solder the pins anytime you remove the board because there would be no way to reach under the boards to unscrew the sockets. Now, as I said, you could do it with threaded inserts built into the board, but then the sockets would have to be top mounted, which is an issue for soldering both sides and adds cost...

Steve

Seems like a good solution Not sure if there's room, but couldn't you also just make the hole in the PCB where the standoff mounts a little larger so you could get a thin philips screw driver down there. And then do away with the standoff? Then you could just insert the screw through the PCB to reach to the socket's mounting flange. And put the nut on the outside of the chassis instead of the inside.

 

[Anonymous]

Looks awesome!

The implications of the chassis mounting... with long PCB pins mean lots of extra work to service the amp. Not gonna go that route.

Why the change of heart? You seemed pretty adamant about not doing it that way. Or were you always planning to do it this way with the power tubes, but not the preamp?

I found a way to do it that made it possible and met my needs for ease of servicing. The key is the 15mm standoffs. Let me explain...

So think about it this way. The pins have to be soldered to the PCB on top and on bottom of the board, so they have to be soldered to the board first - you can't screw them into the chassis first. This also means they have to be mounted under the chassis, not on top. Given that, it is impossible to have enough room to get your fingers between the board and the chassis and far enough back to get a washer and nut over screws through the chassis and the octal sockets. Now you could have a threaded insert built into the chassis, but that wouldn't work either because the octal sockets would have to be mounted on top of the chassis to do that, which can't be done because the octal sockets have to be soldered to the board first... it would also add cost to have the chassis fabricated with threaded inserts...

So... the 15mm standoff, which is threaded completely through solved the problem. You screw the octal sockets to the PCB, solder them on both sides, trim the excess length of the legs and remove the top screw and split washer. Now when you're ready to insert the board, you simply screw in the octal sockets to the chassis from the top and the rest of the board to the PEMs. This was the only way I could think of to make it work to have the sockets screwed to the chassis, make it possible to remove the board without de-soldering the octal sockets and allow the sockets to be soldered on both sides of the PCB.

The long PCB pins are necessary to make this work, but the way you originally suggested wouldn't have worked for me for two reasons. One, you'd have to screw the sockets to the chassis first, so you can't solder them to both sides of the PCB, and two, you'd have to de-solder the pins anytime you remove the board because there would be no way to reach under the boards to unscrew the sockets. Now, as I said, you could do it with threaded inserts built into the board, but then the sockets would have to be top mounted, which is an issue for soldering both sides and adds cost...

Steve

Seems like a good solution Not sure if there's room, but couldn't you also just make the hole in the PCB where the standoff mounts a little larger so you could get a thin philips screw driver down there. And then do away with the standoff? Then you could just insert the screw through the PCB to reach to the socket's mounting flange. And put the nut on the outside of the chassis instead of the inside.

The problem is that getting the 4 screws in that hole for the screwdriver and accurately into a chassis hole small enough to just make it around the screw would be like playing that game Operation where you have to pull out the body parts without touching the sides. I guess there are magnetic screwdrivers, but seems like a pain whereas the standoff thing is completely painless...

Steve

 

[FourT6and2]

Looks awesome!

The implications of the chassis mounting... with long PCB pins mean lots of extra work to service the amp. Not gonna go that route.

Why the change of heart? You seemed pretty adamant about not doing it that way. Or were you always planning to do it this way with the power tubes, but not the preamp?

I found a way to do it that made it possible and met my needs for ease of servicing. The key is the 15mm standoffs. Let me explain...

So think about it this way. The pins have to be soldered to the PCB on top and on bottom of the board, so they have to be soldered to the board first - you can't screw them into the chassis first. This also means they have to be mounted under the chassis, not on top. Given that, it is impossible to have enough room to get your fingers between the board and the chassis and far enough back to get a washer and nut over screws through the chassis and the octal sockets. Now you could have a threaded insert built into the chassis, but that wouldn't work either because the octal sockets would have to be mounted on top of the chassis to do that, which can't be done because the octal sockets have to be soldered to the board first... it would also add cost to have the chassis fabricated with threaded inserts...

So... the 15mm standoff, which is threaded completely through solved the problem. You screw the octal sockets to the PCB, solder them on both sides, trim the excess length of the legs and remove the top screw and split washer. Now when you're ready to insert the board, you simply screw in the octal sockets to the chassis from the top and the rest of the board to the PEMs. This was the only way I could think of to make it work to have the sockets screwed to the chassis, make it possible to remove the board without de-soldering the octal sockets and allow the sockets to be soldered on both sides of the PCB.

The long PCB pins are necessary to make this work, but the way you originally suggested wouldn't have worked for me for two reasons. One, you'd have to screw the sockets to the chassis first, so you can't solder them to both sides of the PCB, and two, you'd have to de-solder the pins anytime you remove the board because there would be no way to reach under the boards to unscrew the sockets. Now, as I said, you could do it with threaded inserts built into the board, but then the sockets would have to be top mounted, which is an issue for soldering both sides and adds cost...

Steve

Seems like a good solution Not sure if there's room, but couldn't you also just make the hole in the PCB where the standoff mounts a little larger so you could get a thin philips screw driver down there. And then do away with the standoff? Then you could just insert the screw through the PCB to reach to the socket's mounting flange. And put the nut on the outside of the chassis instead of the inside.

The problem is that getting the 4 screws in that hole for the screwdriver and accurately into a chassis hole small enough to just make it around the screw would be like playing that game Operation where you have to pull out the body parts without touching the sides. I guess there are magnetic screwdrivers, but seems like a pain whereas the standoff thing is completely painless...

Steve

Yeah, I was thinking you'd have to use a magnetic screwdriver. Either way, same result. Looking forward to seeing the finished product.

 

[Anonymous]

Looks awesome!

The implications of the chassis mounting... with long PCB pins mean lots of extra work to service the amp. Not gonna go that route.

Why the change of heart? You seemed pretty adamant about not doing it that way. Or were you always planning to do it this way with the power tubes, but not the preamp?

I found a way to do it that made it possible and met my needs for ease of servicing. The key is the 15mm standoffs. Let me explain...

So think about it this way. The pins have to be soldered to the PCB on top and on bottom of the board, so they have to be soldered to the board first - you can't screw them into the chassis first. This also means they have to be mounted under the chassis, not on top. Given that, it is impossible to have enough room to get your fingers between the board and the chassis and far enough back to get a washer and nut over screws through the chassis and the octal sockets. Now you could have a threaded insert built into the chassis, but that wouldn't work either because the octal sockets would have to be mounted on top of the chassis to do that, which can't be done because the octal sockets have to be soldered to the board first... it would also add cost to have the chassis fabricated with threaded inserts...

So... the 15mm standoff, which is threaded completely through solved the problem. You screw the octal sockets to the PCB, solder them on both sides, trim the excess length of the legs and remove the top screw and split washer. Now when you're ready to insert the board, you simply screw in the octal sockets to the chassis from the top and the rest of the board to the PEMs. This was the only way I could think of to make it work to have the sockets screwed to the chassis, make it possible to remove the board without de-soldering the octal sockets and allow the sockets to be soldered on both sides of the PCB.

The long PCB pins are necessary to make this work, but the way you originally suggested wouldn't have worked for me for two reasons. One, you'd have to screw the sockets to the chassis first, so you can't solder them to both sides of the PCB, and two, you'd have to de-solder the pins anytime you remove the board because there would be no way to reach under the boards to unscrew the sockets. Now, as I said, you could do it with threaded inserts built into the board, but then the sockets would have to be top mounted, which is an issue for soldering both sides and adds cost...

Steve

Seems like a good solution Not sure if there's room, but couldn't you also just make the hole in the PCB where the standoff mounts a little larger so you could get a thin philips screw driver down there. And then do away with the standoff? Then you could just insert the screw through the PCB to reach to the socket's mounting flange. And put the nut on the outside of the chassis instead of the inside.

The problem is that getting the 4 screws in that hole for the screwdriver and accurately into a chassis hole small enough to just make it around the screw would be like playing that game Operation where you have to pull out the body parts without touching the sides. I guess there are magnetic screwdrivers, but seems like a pain whereas the standoff thing is completely painless...

Steve

Yeah, I was thinking you'd have to use a magnetic screwdriver. Either way, same result. Looking forward to seeing the finished product.

Steve

 

[Anonymous]

So here is an update. I got some great input from GuitarBilly and others over at GAB and decided to make some changes to the control layout.

Biggest change is moving the "OVERALL MASTER" (PPIMV) to the front of the amp and re-naming it "MASTER". It was pointed out that the overall volume is something that people are going to want to change a lot during performance and it would be a pain in the ass for it to be on the back. You can also see that I've renamed the normal channel master "VOLUME". This all seems intuitive now - VOLUME = channel volume, SOLO = solo channel volume, MASTER = overall amp master volume.

Also renamed "FOOTSWITCH OUTPUTS" to "FOOTSWITCH INPUTS", which makes more sense...

Updated models:

Steve

 

[gibson5413]

I can't wait until these are ready to go!

 

[Kapo_Polenton]

Would the Rod channel be more like hot rodding an 800? Would it still be able to get the gain dialed back AC DC tones that a regular 800 can get or would one be better off going plex?

 

[Anonymous]

Would the Rod channel be more like hot rodding an 800? Would it still be able to get the gain dialed back AC DC tones that a regular 800 can get or would one be better off going plex?

The ROD channel can be dialed back to AC/DC tones easily. Unless you are going to be mainly doing a lot of 60/early 70s Marshall classic rock stuff, but want a little extra gain sometimes, I'd go ROD over PLEX...

Both channels do great cleans when you roll off the guitar volume no matter how high the gain is set...

Steve

 

[the4thlast1]

IMO what would top this thing off magically would be to have two foot-switchable gain controls. Now you have a do it all single channel amp that has everything a gigging musician would want IMO. You can have a mild crunch clean channel and a high gain channel via the gain switch. You would have the solo switch ( was a great idea ) which is a def bonus for kicking up the volume for a lead on the fly. With the added second foot-swtichable gain I am suggesting you have a do it all amp in my book. Not everyone likes to roll down the volume knob on a guitar for cleans or mild breakup. I would even prefer having this alone over the solo switch if you had to eliminate something. A pedal could be used in the loop to boost volume for a solo.

 

[russoloco]

Except for the diode clipping and the mercury magnetics tranny's seem like a solid platform thus far

 

[rlord1974]

IMO what would top this thing off magically would be to have two foot-switchable gain controls.....I would even prefer having this alone over the solo switch if you had to eliminate something. A pedal could be used in the loop to boost volume for a solo.

I agree with this ^ as well. If you have run out of front panel space, you could accomplish this by either (a) using concentric pots for the Solo and Volume controls, or (b) putting the two separate Gain controls on the rear panel and leaving the Solo and Volume controls on the front panel (I personally find that I am more likely to adjust volume during a performance than the level of preamp gain, so having the gain controls on the back would not be an issue - YMMV).

I have another suggestion as well that has nothing to do with the tone of the amp.

I see on the rear panel you have separate 1/4" TS jacks for the 'Loop' and 'Solo' switching. I recommend you make one of the two a 1/4" TRS jack and wire it with the other 1/4" TS jack. Why? This would allow someone to use a two-button footswitch that has only one cable and one stereo male connector with your amp without needing a Y-splitter - for instance, if the included footswitch is accidentally left at home, is misplaced or breaks at a gig (not that that would ever happen )! It would also allow someone to use other rack relay switching systems that use TRS male plugs for switching purposes. The best part of all is that this would only cost you about 2 extra minutes of labour and $0.10 in solder, and would make the amp's switching much more flexible. I wish all amp manufacturer's that use separate 1/4" jacks for external switching would do this!

 

[gtr31]

I could be wrong but I thought amp was planned to come with foot with for solo and loop??? no