Dumble clone first build questions

[Mharv]

Hey! Im new to the forum, seems like an incredible resource for new builders.

Im just about to start my first build based off of the stickied 3rd gen dumble thread in the dumble files sub forum and the ceriatone ots 50 w layout found on the website.
ive ordered most of the parts, but am yet to purchase transformers. i dont know too much about transformers so im looking for a bit of guidance. so far i have found a pt
(equivalent to 022749) and an ot (equivalent to 022871) (fender transformers) for sale locally and am wondering if these two would work with these builds?

Thanks for your time guys,

[Stevem]

what impedance speaker(s) are you thinking of using and what over all do you need more from the amp, a blues nature on the soft side, or a loud punchy amp with tight Bass?

[martin manning]

Greetings. This thread belongs in the Dumble Discussion forum. Maybe one of the Mod's will move it?

Fender 022749 is a Deluxe Reverb PT, and much too small. You need an equivalent to 022814 as listed on the layout.

[Mharv]

I have a 16 ohm orange cab that i will use but im also considering putting it in a combo eventually (not sure which speakers yet).
Probably going for more of the second option with the tight bass i guess.

Sorry about that, martin manning, i thought it was more related to technical discussion than a specific dumble amp.

OK, so bigger PT it is!

thanks for the quick responses!

[Stevem]

That Fender OT will not work for a 16 ohm load, you need something like a Hammond 1650N with a 4200 ohm load and a 50 watt or better rating for tight Bass.

[martin manning]

i thought it was more related to technical discussion than a specific dumble amp.

No worries, but if this is the first of many questions on your adventure, then it will be best to keep them together in one thread, and it will be D-specific.

This is a fairly complicated project for a first try. How much electronics background do you have?

[Mharv]

I have a fair bit of experience soldering etc. just not much on the theory.

so neither transformer will do? On the ods layout i see it has written 022871 for the ot. or do you mean it wont achieve that tight bass tonality?

Do you guys have any transformers that you can recommend?

[martin manning]

I have a fair bit of experience soldering etc. just not much on the theory.

so neither transformer will do? On the ods layout i see it has written 022871 for the ot. or do you mean it wont achieve that tight bass tonality?

Do you guys have any transformers that you can recommend?

If the one you have picked out is like the original then it has only one 4 ohm output. There are replacements with multiple taps, e.g. http://www.classictone.net/40-18009.html

Scroll down to see various options.

[Mharv]

thanks for the link martin.

so for pt i could go this one: http://www.classictone.net/40-18097.html
and for ot this: http://www.classictone.net/40-18009.html

just picking the numbers matching with those of the ods 3rd gen layout will work?

[martin manning]

Why not? New-made equivalents to the transformers HAD used, with the addition of multiple secondary taps if you need that flexibility.

[Mharv]

Hey guys, i have a few new questions regarding the build, please bare with me, im a complete newbie.

Q1. Looking over the ods 3rd gen layout, i saw this and was wondering what it is. (image below)

Q2. What is the underlying Isolation material underneath the circuit boards?

Q3. How simple would it be to remove the FET circuit? (image below)

Q4. Would it be possible to put in an impedance selector switch like the ceriatone ots layout? (image below)

Q5. Finally, unrelated to the actual build, is it possible to rename the title of this thread?

Thanks for looking guys, Mitch

[tele_player]

Hey guys, i have a few new questions regarding the build, please bare with me, im a complete newbie.

Q1. Looking over the ods 3rd gen layout, i saw this and was wondering what it is. (image below)

That's the AC power cable.

Q2. What is the underlying Isolation material underneath the circuit boards?

Looks like Dumble used Formica for that. If you're not trying to make an exact copy, just use standoffs, no insulator.

Q3. How simple would it be to remove the FET circuit? (image below)

Just leave it out.

Q4. Would it be possible to put in an impedance selector switch like the ceriatone ots layout? (image below)

If you have an OPT with multiple taps, yes, of course.

-Robert

[martin manning]

If the FET booster is eliminated, most put a resistor to ground (150-180k) in its place to maintain the preamp voltage levels.

The originator of the thread can edit the thread title by clicking on the edit button in the first post.

[Mharv]

Thanks again for the responses guys.

So for the FET i could just leave it all out except the 150k resistor between the NOR jack and B+5?

I have sourced all the parts apart from the relay power transformer. i am having trouble finding the triad f-313x here in australia.
I was wondering if i could use the voltage regulator ( http://www.hobbytronics.co.uk/datasheets/L7812.pdf ) in the ceriatone ots
build in place of the triad transformer? or would i be better off finding a similiar transformer ( http://www.jaycar.com.au/productView.as ... TID=1002#3 )
and sticking by the ODS 3rd gen layout?

also, how important is it that the wiring for relay and STBY are AWG 20 teflon? I have AWG 20 600v pvc wiring on the way and
didnt want to buy an entire reel of teflon stuff (it was about 50$) if its a big deal, i might try find some smaller pieces of wiring locally.

Thanks for reading!

[martin manning]

If you leave out the FET booster just put a 150k-160k from B+5 to ground.

The Jaycar 12.6 VAC 500 mA transformer will work, and you can wire it as shown in the layout using half of the secondary (6.3VAC), or reconfigure the relay supply as a FWB using the whole secondary, and add a 12V regulator if you like.

20 AWG 600V PVC will be fine.