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ODS with 4xEL84s

ALL, I am here because my brother and I were in the process of building a ODS but decided to use a quad of EL84s instead of 34s. Well my brother has since passed away from colon cancer in Augest '25. He was going to build his own eyelet boards and engineer this whole project. Then I found this site with the boards and layout and thought I could probably do this....? We had already purchased the transformers and chasis, Hammond 370FX and 1750G. I really hope if someone could just chime in with some "definite changes" I will need to make to get this thing to function with 4xEL84s. I just purchased a Hammond 194E choke (VoxAC30 30H 100ma). I'm thinking that might have been a wrong move. According to Google A.I. it was.... This is really a big undertaking for me.But thought it would be a huge learni…


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Dumble Resistor Wattage

I've noticed a discrepancy in three of the resistors listed on the BOM for the Dumble builds, when compared to the layout and schematic. R24 is shown as 1 watt in the BOM but 2 watts on the schematic and layout. R25 and R26 are shown as 2 watt on the BOM but 3 watts in the layout and schematic.

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102 dumble bass treble, and mid stopped working

Can anyone help with any ideas why they would stop working?

Thank you, Bill D.

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Can you give a bit more details? Have they worked before? Did you change anything? Are you in clean or OD mode? Do you have the boost on?

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Dumble ODS 3rd gen build, PT/HT query

Hi all,


Hope everyone is well.

I am currently building the ODS 3rd gen. I the bom it specifies a fender twin PT (022756) Hammond make an exact replacement model no 290fex. My issue is the schematic and the layout call for a 3.15v tap from the transformer but, the required PT doesn't have it. Am I missing something here? Is there supposed to be a way to connect the heater wires even without the 3.15v tap?


Any help would be greatly appreciated.


Thanks

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Dave East
Dave East
Jul 29

The 3.15 volts is for each side of the tube heaters. The Hammond 290FEX doesn't have a center tap (the center tap would connect to ground, splitting your 6.5 volt heater supply into two 3.25 volt legs.) You can easily make what is called an artificial center tap. You would use two 1/2 watt, 100 ohm resistors to connect each heater tap to ground. Most commonly done where the heater wires connect to the pilot light, but since the Dumble schematic is using an LED, you would need to ensure that it was connected before (on the transformer side) the 2 watt, 330 ohm resistors that is dropping the voltage to the LED. There are a ton of different examples online. Just search for "tube amp artificial heater center tap".

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Hello, I bought 4 boards from your store and paid for them, but you refunded me. I don't know what happened, and I asked you but you didn't reply. What exactly happened? I have already arrived at the computer case, only the PCB board is missing

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102 12v section @450ma

I have built two of these before one with this transformer which I can't remember were it hook up and one with out. I assume I had a tap from my power transformer for this. I just don't see the separate transformer in the layout for the 102. I must be getting old and forgetful. I little help would be appreciated. Bill

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The AA Dumble board has a Delon-type voltage doubler that feeds the 7812 voltage regulator from the 6.3 VAC secondary winding. Allows you to make 12 VDC from the filament supply so you don't have to install a separate 12 VAC transformer.

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Is anyone else frustrated with the BETA version material list for fox board?

Is anyone else frustrated with the BETA version material list for fox board?

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Tom Scioscia
Tom Scioscia

Shipping times?

Hi there! I ordered a SLO PCB last week (Thursday night, which may have been Friday morning in the UK) but haven't heard anything regarding shipping. Admittedly, it is to the US, so I imagine that complicates matters, but I've even emailed Andrea without reply.


I also noticed that he had posted on Reddit yesterday but somehow his account got banned, which is confusing since I can see deleted posts (I have moderator tools at my disposal) and see absolutely no reason to have banned his account from the whole platform.


So, I'm just wondering if everything is alright over there in London.

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Hi Tom!

Thanks for the purchase first of all. And yes, everything alright here, all parcels are being handed out to the courier today :)

Unfortunately I’m not sure what happened with the Reddit post: attaching the link to my webpage might have triggered the banning 🧐


Cheers from London

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Dumble 102 Completed!

After many personal delays, I finally finished the Dumble 102 build! Excellent board and great experience. To those who have built it or heard one: is the drive channel meant to be so... different? The distortion sounds super compressed, bright, and fizzy. It's way hotter than expected, but it's very much unlike a cranked Fender or a lower-gain Marshall. A category of its own. A little splatty, a little velcro-y. I realize this is stupid buzzword Bingo.


The clean channel is amazing and to die for. I'm just curious if something may be wrong with the drive.


Thanks!

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The ODS drive channel is difficult to dial in. I'm not surprised you're having trouble with it. The culprit, and the solution, is the trimmer pot that feeds the V2 circuit. If it isn't set just right -- and its sweet spot is VERY narrow -- you'll get too much drive, or so little that the drive channel adds nothing. You may also want to try the "Ayan mod": https://ampgarage.com/forum/viewtopic.php?t=33519 I installed it with 4.7 nF in parallel with 470K and I like how it cleans up the OD sound.

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