- The Woefully Misguided Turretboard Stiletto Ace Thread -

[frontsideboneless]

Hello to you all.

The following is my ongoing attempt at creating a turretboard layout for a Mesa Boogie Stiletto Ace.

Stiletto Ace Layout v02.pdf

I am a complete beginner, so naturally I have decided to jump headfirst into the deep end of shark infested waters! I really want to learn and I thrive in the challenge, so I have chosen to try and do something difficult to help me understand things better.

This is my first time doing something like this and my first time using the DIYLC software so please forgive my ineptitude (and messiness of the layout, please let me know any tips on using DIYLC better)

The main thing I would feedback and criticism on is the obviously the layout (especially with regards to noise) but I also have a few questions I hope you can help me figure out.

This is still a work in progress and I am yet to draw heater and ground connections, signal path and routing on this layout.

This is the schematic I am working from (I have deleted the 2nd pair of EL34s in the original schematic).

Stiletto Ace Schematic.pdf

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In this project these are things I don’t care about and as such won’t be including.
Channel independent rectifier selection.
Solo boost.
Bold/Spongy switch (As I understand this is a proprietary feature of specific mesa power transformer… I can always just buy a variac later.)

Footswitching is not important to me, but then I wonder what the utility of having 2 channels (with individual controls) would be. Why not just have a single channel amp with 6 “modes” or just have the possible routing all on switches? (Though that may be switch overkill and it may be difficult to remember which switches are or aren’t in the signal path and inoperative in certain combinations). I really would like to hear what you all think.

I may add the fx loop and fx level further on in this project, most likely on a daughterboard for space reasons.

I only want the slave output if I can use it as a DI straight into my interface for use with IRs.

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Obviously, the switching is where I am having the most difficulty. I don’t care at all if I have a bunch of switches on the panel, in fact I would quite enjoy the manipulability. As long as any popping won’t damage the amp or the speakers, I am ok with popping when using switches.

So far I have deduced that the following can just be connected to SPSTs,
R12 V2A Mixing Resistor
C9 Channel 1 Gain Bright Capacitor (perhaps this can be on a pull pot)
R16 V1A Cathode Bias Resistor (as long as the J175 isn’t important)
C11 V1A Cathode Bypass Capacitor (same as above)
R33 V2B Cathode Bias Resistor

However, I am not sure about,
C16 V3A Cathode Bypass Capacitor (I suspect an SPST is fine)
R14
R47

When it comes to the rectifier, channel and mode selections I am completely in the dark, especially because I don’t know the individual modes signal paths. Before diving into the implementation of modes or routing options, I’ll simply ask could a 4PDT or a 6PDT be used for selecting between Channel 1 and Channel 2?

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Other general things I want to understand are,
How the presence knobs are connected.
The 3 capacitors between the export power transformer’s primary windings shown on the schematic. (I am in the UK).
What resistors in the circuit require higher wattage ratings, the schematic only shows 3 5Ws (R62, R63 + R122).
How do I find out what kind of ferrite bead and choke are used.
Why is the voltage given at the connection of R55 + R56 -38V, when the bias supply from the connection of C47, R83, R82 + R81 is labelled -39V.
The purpose of RY1/R (which I presume is used for muting) and if I need to have R1 + R2 on a switch to ground.


Thank you for reading and I’m very excited to get further along in this endeavour and develop my knowledge and skills.

[Phil_S]

It would help a great deal if you can tell us about your general background in electronics and whether you've every worked with tube amplifiers. Are you a college educated electrical engineer or maybe you've got some sort of technical certificate or military training? Built any pedals? Do you have tools, a meter (what kind) and anything else? Otherwise, you should expect people to treat you like you don't know very much. Background will help move the conversation to a more appropriate level.

Your enthusiasm is admirable. You've chosen a challenging amp to build. I suspect from what you posted about your experience that this project is more than a little stretch. The thing about building amplifiers is that hands-on experience teaches you many things that are not readily apparent, even if you been taught and told about them. Perhaps you'd be better off starting off with an easier single channel build?

[GAStan]

+1 to everything Phil said. I too admire your enthusiasm.

A cautionary note: tube amps, for me, has proven to be a very deep rabbit hole and I'm still on my way down...enter at your own risk

The amp you have chosen is hybrid, both tube and solid state. Either one can prove to have a steep learning curve. Combining the two may prove to be extremely challenging.

A bit of advice from techs much more experienced than myself that I'll repeat: first get the amp working as it was intended, then start modifying one thing at a time.

The above is said with the best intentions. My intent is to help you achieve your overall goal but consider doing so in smaller steps such as Phil suggested.

[Phil_S]

I finally looked at the layout. Frankly, a dozen pots on the front panel scares me. I'm pretty sure I'd need a 24" x 8" chassis to get all the parts in it. The cost of the chassis alone may be a discouraging factor. In a factory production situation, they know how to pack things tight that ordinary people can't or won't do.

[frontsideboneless]

Whilst I absolutely understand the impetus for doing so, building something like a Champ, from an existing layout isn’t really going to teach me what I want to know. I would liken it to paint by numbers. What I am trying to do is go out of my way to discover what makes a layout good and how to adapt schematics to a layout that follows these principles. As I stated previously, I am open to creating a single channel adaptation (and adaptation/modification/improvements in general), however translating the switching sans relays is something that I would very much wish to understand.

The considerations for actually building this are not yet a factor in this project. Even just creating an effective and valid layout is a success for me, presently. I am going to work towards that and only then we will then see about manifesting it into reality.

That said, as long as the amp will fit on top of a Marshall 1590B, I don’t care how large it is. The original amp uses 16mm pots arranged in two rows on top of one another and I may do this too. I only have arranged all of the pots in a single row in my layout for visual clarity, as I don’t yet know how to use DIYLC in a more “legible” manner, and I apologize for the messiness of my layout. Is there a recommended wire colour scheme that would make things more coherent?

When it comes to a chassis, there is a company called Modulus Amplification here in the UK that offers chassis’, however if price is an issue, I see no reason why I could not fabricate one myself for much cheaper from some 14-18ga sheet metal, if I built myself a metal brake. But again, this not a prescient issue at this point.

I am just an ordinary guy who understands that the secret is to just do things. I have experience with creating pedals, audio stuff and synthy noise thingys but I’ve never played with tubes or higher voltages.

Even if I never build this but nonetheless create a good layout, I see value in having contributed something to the medium, especially something that I don’t believe has ever been done before (A turretboard layout of a Stiletto Ace). But it is learning and discovering new things that I desire the most.

[TUBEDUDE]

Greeting citizen, and welcome to this addictive venture.
You can absolutely accomplish your vision, but here's why we are suggesting a slightly different path to your goal.
You say "What I am trying to do is go out of my way to discover what makes a layout good and how to adapt schematics to a layout that follows these principles."

Of the numerous factors that are needed for a good layout, most can only be learned by the experience of building an amplifier or ten.


"The considerations for actually building this are not yet a factor in this project. Even just creating an effective and valid layout is a success for me, presently. I am going to work towards that and only then we will then see about manifesting it into reality."

The only way to establish a valid layout is to build it and prove it functions correctly.
Executing a new build, or adapting a build to a different layout, will inevitably create issues of noise, hum, oscillation, and/or response irregularities that make experienced builders frustrated. With limited knowledge and background it will be a mammoth task.
I'm not recommending building a Champ, but if your goal is to adapt a proven design to a different layout, starting with a simple amplifier to adapt will give you a greater chance of success. And that will give you some of the experience needed to establish a good layout with more complex designs.
This addiction can be rewarding.
To that end I recommend you have a good multimeter, soldering station and an oscilloscope. Practice soldering until you can make good shiny joints on a variety of joints, turrets, switches etc.
Again, welcome! Keep us posted and good luck.

[Reeltarded]

Practice soldering until you can make good shiny joints on a variety of joints, turrets, switches etc.

That!

[WhopperPlate]

Practice soldering until you can make good shiny joints on a variety of joints, turrets, switches etc.

That!

+10000000000000

This will prevent the most headaches and tail chasing while troubleshooting builds . It’s hard enough dealing with inconsistent and possibly defective components out of the box , but complicate that with poor soldering skills and there will be a struggle to tell what’s causing each issue. You will be surprised how a bad solder joint can seemingly look good …

There are some great articles on lead dress and layout , and I suggest you read up on the Frequently asked question sub forum . Merlin Blencowe , Aiken Amps, Robrobrinette… all found easily within web search results .

Your enthusiasm is inspiring, and exactly what you will need to tackle this project. Keep in mind that it is easier to answer one direct question than approach a dozen hypothetical ideas. I recommend using the forum to ask specific questions , rather than shotgun every hypothetical quandary that has you scratching your head .

You may not be building a champ , but it’s very helpful study up on what’s already worked before to understand how to approach your project . Start downloading schematics and layouts of all the classic amps and get an idea for what has already worked .

Cheers

[bepone]

a small note: there is enormous experience needed to tame high(er) gain amp!

[romberg]

Whilst I absolutely understand the impetus for doing so, building something like a Champ, from an existing layout isn’t really going to teach me what I want to know.

Rather than diving into the deep end of the pool with an amp at the extreme end of the complexity scale, I'd argue that there would be quite a large amount one could learn by studying less complicated amps and then working your way up. Don't work from an existing layout.

Take a champ schematic. Or a marshall jtm 45, fender bassman, etc. Then using just the schematic, draw your own layout. When you get stuck, take a look at how others do it. Just like doing math problems helps solidify the theory trying your own layout may show you how good (or sometimes bad) the original was. I bet you'd be surprised at just how much you can learn by drawing up a layout for even a simple amp.

Can you make a better layout for these old "paint by numbers" amps? Sure you can. But you can also easily make one that is worse. Best way to get good at this sort of thing is to just do it. But it is easier to get the basics down with a less complicated circuit.

Mike

P.S. A really good place for information about tube guitar amplifiers is https://www.valvewizard.co.uk/ There you can find several free chapters from his books (which I highly recommend). The grounding article ( https://www.valvewizard.co.uk/Grounding.html ) is very good and shows that you can improve upon old layouts. A good exercise is to read this chapter and redo old layouts with improved grounding schemes.

[timrobertson100]

Welcome, and nice project you have.

For your question on resistors, this thread probably answers what you need to know.

You're correct to assume toggle switches are suitable for swapping in/out caps and resistors for tuning on the preamp cathodes - it's pretty common.

Before diving into the implementation of modes or routing options, I’ll simply ask could a 4PDT or a 6PDT be used for selecting between Channel 1 and Channel 2?

Without looking at the circuit in detail I suspect a challenge you will face will be noise due to a lot of wiring and it being in close proximity. Shielded wires may help but I think this might be difficult to get satisfactory results.

Just a thought - it might be an idea to buy the transformers and start in a scratch chassis, building up one channel, and then progressively adding more to it learning along the way. When you arrive with something you want to keep, port it to a final chassis.

[maxkracht]

+1 to what everyone else has said. I fully support the learn by doing approach, but agree that a complicated, two channel, high gain, amp is asking for trouble your first time around. I had my fair share of somewhat complicated build ideas as a beginner that ended up being more discouraging than helpful. I have also rebuilt or repaired plenty of failed first projects that were too far beyond the builder's skill level. (It is surprising how wrong, and dangerous, you can make a champ.) Many of these skills may be simple, few are easy.