Chassis / Layout question.. first build! :)

[unknowntome]

Hello! Hoping you all can help me with my project and more specifically answer some layout and chassis questions for me. This is my first amp build (have been making guitar pedals for sometime) and ive got loads of woodworking experience which is where the chassis comes into it.

Im planning on building the Benson Monarch layout that’s been unpacked on this site. I want to house it in a ‘boutique’ exposed tubes headphone amp type chassis with wooden sides and aluminium top. This build will sit in my lounge room.. ive got other amps for gigging and jamming.

My main question is, for the purposes of having maximum flexibility with regards to tube and transformer layout, are there any issues with separating the preamp side and the power filter side of the turret board (ie. having two boards) and have them mounted on opposite sites of the chassis on the side panels? (Ill also be abiding by some universal principals re transformer orientation and tubes placement etc).

Below ive attached a pic of the layout (can be found on the benson monarch thread - thanks BobL) as well as an example of the type of amp build.

Cheers!
Tom

https://imgur.com/a/JH1RIY1

[johnnyreece]

Several builders use a separate board for power supply and preamp/PI. You should be fine, barring something extreme. Good luck!

[unknowntome]

Thanks for responding.. are there any issues with running wires across (or around) the chassis from one board to the other? I’m think about length.. there seems to be 3 connections one if which is ground.

[johnnyreece]

The ones you want to be most careful about would be the grid wires. I'm not sure exactly how you want to split it, but assuming you're separating the PS caps from the rest, I can't think of anything that would keep you from doing that. Heck, Fender used to run theirs to a doghouse outside the chassis.

[fred.violleau]

Having build a few D clone amps, I always separate the preamp from the PS. That being said, it comes with a great attention to lead dress for the B+ wires (90 degrees angle when crossing signal path), and grounding scheme. I would advise you read this great article https://www.aikenamps.com/index.php/grounding

Have fun with your build !

Fred.

[unknowntome]

Hey Thanks for that.. I've stumbled upon that article before however will take a more precise look at it... lots to consider!

I've attached a link with my ideal layout which I think adheres to most principles re layout however im certain that you guys can probably spot something that I haven’t noticed. Love to get some feed back before I commit to the build. Let me know if you need some help deciphering the layout.




https://imgur.com/a/wE4lnoq

[johnnyreece]

Looks like there will be several long grid wire runs on that setup. Not sure of the scale, but would it be possible to mount the preamp board between the power tubes and Preamp tubes?

[ChopSauce]

Where's the input?

I'd suggest you push the knobs on the left to make room for the input jack, as close to V1 - put rightmost - as possible, far from everything else.

Also you want your preamp tubes to read 1, 2, 3 from right to left.

IMHO you should either reconsider departing from safe designs, either delay the build the time to learn some more about the rationales for my suggestions.
- if I'm right -

EDIT2: if you want to build something along the lines of living room hifi amps, why not P2P inside?

I made an AC4 like that, which turned pretty original with respect to its layout

DSC08543.JPG

That has the advantage of flexibility, for your layout suggests some conflict between the horizontal (as seen on the computer screen) arangement of preamp tubes and vertical arrangement of the preamp board.

[johnnyreece]

EDIT2: if you want to build something along the lines of living room hifi amps, why not P2P inside?

Stellar idea! Depending on how simple/complicated this ends up being, the layout (as presented) seems like an excellent candidate for PTP. Also, to answer your question, it seems the input is on the top right. If it were mine, I'd see if there was space for the input on the other side (near the knobs), and maybe switch the positions of V1, 2, and 3 to something that has them lined up in a row (with V1 closest to the input).

[unknowntome]

Where's the input?

I'd suggest you push the knobs on the left to make room for the input jack, as close to V1 - put rightmost - as possible, far from everything else.

Also you want your preamp tubes to read 1, 2, 3 from right to left.

IMHO you should either reconsider departing from safe designs, either delay the build the time to learn some more about the rationales for my suggestions.
- if I'm right -

EDIT2: if you want to build something along the lines of living room hifi amps, why not P2P inside?

I made an AC4 like that, which turned pretty original with respect to its layout

DSC08543.JPG

That has the advantage of flexibility, for your layout suggests some conflict between the horizontal (as seen on the computer screen) arangement of preamp tubes and vertical arrangement of the preamp board.

Hey - thanks for your input.

I really like the idea of point to point and can see the added flexibility however not feeling so confident in executing it.

The size isn’t confirmed yet although will be approx 300mm wide x 220mm deep x 100mm high… something like that give or take. Are there any issues re longer grid wires? Specific wiring recommendations?

Ill re-arrange the preamp tubes 1-2-3 from right to left and move the input to the front (or side) next to V1.

anything else that's jumping out? I've just waiting on the resistors that I can start! also, once I settle some of the design/layout considerations I can begin work on the chassis etc.

thanks again!

[unknowntome]

EDIT2: if you want to build something along the lines of living room hifi amps, why not P2P inside?

Also, to answer your question, it seems the input is on the top right. If it were mine, I'd see if there was space for the input on the other side (near the knobs), and maybe switch the positions of V1, 2, and 3 to something that has them lined up in a row (with V1 closest to the input).

Hey - that's definitely the first thing i'll change.. potentially have the input installed on the side of the chassis near V1.

[ChopSauce]

I am sorry I don't remember precisely any document in english, about the basics of analog/tube amps layout. You can probably find some usefull informations on other forums (EL34 world or some site about "diy tube amp" - for example) and their design documents, if any?

If you can read french, maybe you can find some usefull information at: https://www.projetg5.com but I'm not even sure.

Otherwise, you can start with reading material on steroids https://ampgarage.com/forum/viewtopic.php?f=6&t=9023 in this section of the forum.

[Phil_S]

The size isn’t confirmed yet although will be approx 300mm wide x 220mm deep x 100mm high… something like that give or take.

Are you making your own chassis or buying one? If you are making it, 300mm is rather short, but probably OK for this project. 220mm front to back is good and will give you some extra room. 100mm high is very high. I suggest 50-60mm is a better size unless you plan to put the transformers inside (not recommended.)

[unknowntome]

The size isn’t confirmed yet although will be approx 300mm wide x 220mm deep x 100mm high… something like that give or take.

Are you making your own chassis or buying one? If you are making it, 300mm is rather short, but probably OK for this project. 220mm front to back is good and will give you some extra room. 100mm high is very high. I suggest 50-60mm is a better size unless you plan to put the transformers inside (not recommended.)

Hey Phil..I’m making my own chassis (timber sides and aluminium top plate).

100mm is a bit high although it will have to accomodate the turret boards which I plan on securing to the side panels.

[Phil_S]

100mm is a bit high although it will have to accomodate the turret boards which I plan on securing to the side panels.

This is unconventional. Please make sure you think this through. You'll need the side panels to mount pots and jacks. If I understand your intent, this would mean securing turret boards on rather long standoffs and I think it could be awkward to secure the boards and to work on the amp. I am guessing you have at least two boards. I think you might be better off to consider making it wider than 220mm and mount the turret boards side by side in a more conventional orientation. If you make the chassis 300 x 300 x 60, you can probably drill for tube sockets down the middle and mount your boards in a conventional orientation. If you like the wood look, use veneer on the 60mm side panel. Of course, it's your project. I'm not telling you what to do.