Volume Knob Board - what are the dimensions of the knob post?

My first ever DIY project is to convert a vintage Montgomery Ward Airline radio into a modern streaming device. I am using the Up2Stream AMP v4/mono to power a Dayton Audio speaker (replacing the original speaker).
I would like to have an analog volume control for the v4, so I’m looking at the Volume Knob Board for this purpose; however, I would like to use one of the original knobs from the radio instead of the stock knob that comes with the board.
Question: Does anyone know the dimensions of the knob post? Length and diameter would be helpful, but most important is the diameter. I’ve looked for specs on the Arylic site and can’t find anything.
Many thanks in advance for your help!

I do not own the volume knob board but if they use the same knob as for the Up2Stream 2.1 amp board (what I assume from comparing the product pictures) then the diameter should be 6mm. As far as I know, this is the standard for most rotary encoders. The length (axis plus thread) should be about 20mm. Unfortunately, I cannot measure the length exactly since the knobs of my board cannot be reached from outside the speaker box (used my own knob for volume control).

By the way: Nice project. Love the art deco look of the radio :+1:.

Regards, Sven

Hi Sven - Many thanks for your reply and this helpful info. It’s good news, because the diameter of the original knob posts are exactly 6mm - seems like this standard has been around awhile! The radio is ca 1936, so its definitely deco. I’ll share a full design post with pictures after I complete the project.

Love your boombox project, by the way. The vintage amp vibe is excellent, and I am very envious of your system design skills. I’m just getting started and have a long way to go. It’s great having experts like you who are willing to guide beginners like me. Thanks for being so generous with your time!



Hello Andy,
nice project you started there, especially the old receiver looks really nice! I also rebuild old receivers from time to time, mostly the diameters of the old buttons fit exactly to the new 6mm axles of the potentiometers. But I have three questions because of your pictures: What type of Dayton speaker do you use exactly? Why are you running 2x2 cables to the speaker? With a mono output, does that make sense? ((Stereo: R+,R-,L+,L-) (Mono: +,+,-,-) Last question: Does the push function of the Arylic Volume knob finally work on your amp? Thanks for the short feedback! Greetings Jörg

Hi, I am also working on transformation of a vintage radio and the volume button was an issue to integrate So I have used an Aluminum profile and a 6 mm extender so I can adjust the length to my need

You can find the part on aliexpress

Do not hesitate to ask more :slight_smile:

Hi Joerg,
Sorry for the slow reply. I am a beginner in this forum and messages from Arylic user forum are not in my workflow yet. I will get better!
To answer your questions:
1 – The speaker is Dayton Audio PS180-8 6-1/2" Point Source Full-Range Neo Driver (Parts Express part #295-344)
2 – Regarding the cables: I could be completely wrong about this, but my assumption is that with the jumpers set to “mono” mode, the amp delivers current to all 4 terminals, so connecting all 4 is necessary for the driver to receive all current available from the amp. Maybe R+R- and L+L- are bridged so this is unnecessary? I’d welcome any guidance you may have. Note: the 2 cables from RR and LL are combined and connected to R and L terminals on the driver. Seems to be working fine.
3 – I haven’t received my volume control board yet, so I’ll post a reply once it is here and implemented.
Thanks - Andy

Hi Philippe - Thanks for your suggestion about the volume knob. I am hoping to re-install my volume knob on the original electronics chassis from my vintage radio and use the chassis to hold my circuit boards and such. I want to try to use circuit board standoffs and let the original chassis house the new electronics. Not sure if it will work. I’ll let you know how it goes.

Great looking solution, by the way. Can we see pics of your radio?


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