Dumblelator straight-up, with a twist

[martin manning]

This is the classic serial loop with no extra frills. I don’t use rack gear, so I wanted a stand-alone unit. The enclosure is a Bud “Slimcab,” which is actually a ¼ rack box (1u height, half-width, and half-depth) so it is rack-mountable if desired with the addition of some long brackets. Right now it is on the rubber feet that were supplied with it. The 1/8” aluminum front and rear panels are drop-in flat plates, and so are easy to machine. These things are not cheap at ~$70, but it makes an attractive unit, IMO.

The PT is an Allen TP-2X, which just fits in the 1u height and produces ~365V at the reservoir with a FWB. To squeeze the circuitry in, the board layouts had to be compacted and the main board layout is flipped to get the best positioning for the shielded cable runs. The chassis-mount shielded tube socket on stand-offs worked out well, trading the eyelets needed for a PC mount socket for the wire pigtails. It also allowed tying the socket and the board directly to the chassis with a third L-bracket at the lower stand-off for some extra support when changing the tube.

What a lot of work to run one 12AX7! But hey, it looks like it will be a great asset for tone shaping by itself, and for running FX.

[ToneMerc]

Very slick, nice job!

TM

[Tonegeek]

The bar has been raised!

[Cliff Schecht]

This is not how HAD did it and therefore it is imperfect. Sorry man...


But seriously, it looks great! I'd be proud of that one. A lot of times when people go for maximum crammage they make devices that are impossible to work on. This looks well planned and well built. Again great job!

[martin manning]

Thanks guys. I was just tickled that it didn't hum, but I guess it was pretty low-risk, as I'm following the ground scheme in the other layouts. It was time consuming to wire due to the limited space. A bit more on the voltages: The dropping string is per the schematic right now, and it has ~330 and 233V on the two supply nodes with 119VAC. It sounds great, but I think I'll reduce the 15k just to see what happens (should be able to get another 10-15V), and maybe scope it to see where it clips.

[rogb]

Nice work Martin!
I built a full rack width Dlator, but I am now considering downsizing the case to your specs, so thanks!
It will sit nicely then on top of my 13" o/d combo cab, or maybe even inside at the base of the cab!

[Dr d]

Really neat work, Martin. Makes perfect sense to reduce the size if not useing rack effects. Great work!!!

[DonMoose]

I am OUTRAGED that this thing looks so perfect. Can you point me to photos of your shop/work area?

/ a poor workman blames his tools, but he may just understand he IS a tool

[Structo]

Man that looks good Martin!

Way to cram in the components!

I may have to look into one of those transformers.

[stelligan]

Cool size! Does that fit inside the bottom of a head for you?

[martin manning]

Thanks for the kind words, rogb, Dr d, and Structo! I guess you guys in the UK would have to find another small PT for this layout. There are likely some flat-packs or toroidals that would fit in this size box. Don, ha! My shop is a mess! Stelligan, it's still too big to fit in the cab... too bad, that would be cool.

So, after a swap of the first dropping resistor to 3k9, I now have 358 and 252V on the PS nodes, and I'm calling it done. Attached is the layout in case anyone else wants to do one like this. The last page is a guide for positioning the rubber feet.

Edit: revised schematic to correct diode orientation in FWB Layout moved to first post

[talbany]

Martin
Very Cool!! Nice unit..I bought a computer monitor switch box at a local thrift store about that size and have been meaning to build a loop with it to go along with my new LXP-1..Throw them on top of the amp no (rack needed).. This helps get me off my butt and build it..

Congrats! and Thanks for the Layout!!..

Have a good weekend!!

Tony

[martin manning]

Thanks, Tony. I was thinking this box looks like one of the Gandalf modems that were common some years ago. Old gear like that is a good source of bargain chassis... usually new front and rear panels are easy to make, too.

Re the layout, you're most welcome. Only too glad to give one back!

Cheers!

[kevster]

Thanks, Tony. I was thinking this box looks like one of the Gandalf modems that were common some years ago. Old gear like that is a good source of bargain chassis... usually new front and rear panels are easy to make, too.

Re the layout, you're most welcome. Only too glad to give one back!

Cheers!

I used to maintain a HUGE Gandalf system when I was stationed at West Point about 20 years ago. The boxes we had were the older, sky blue colored ones. Been a long time since anyone mentioned Gandalf.

Cool layout for sure, but I'm going to have the D-Lator in the amp cabinet (head). If I were ready to go to a rack system, this'd be great.

[Tonegeek]

Thanks, Tony. I was thinking this box looks like one of the Gandalf modems that were common some years ago. Old gear like that is a good source of bargain chassis... usually new front and rear panels are easy to make, too.

Re the layout, you're most welcome. Only too glad to give one back!

Cheers!

Modem cases work great for foot pedals too This was an ancient Boca 1200 baud Modem that Henry H (Redplate) made a label for: