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February 19, 2025, 12:59:35 PM

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#21
Amplifier Discussion / Re: Ruby amp from LM386M-1 mod...
Last post by J M Fahey - February 11, 2025, 01:06:02 PM
Good!!! :dbtu:

No need go get *exact* cap values if not available, +/-20% is always close enough.
At least it was close enough for Leo Fender ;)

We are pampered by modern parts availability and precision; but way back then ... not that much ... yet they made killer amps.

Please continue posting your experiments  :tu:
#22
Amplifier Discussion / Re: Ruby amp from LM386M-1 mod...
Last post by blackcorvo - February 11, 2025, 12:47:03 AM
I had some free time at work today so I drew this perfboard layout for the buffer, and made it once I got home - worked first try.

Attached are the layout and some pictures of the project so far.

Only difference between the Hiwatt/Bassman mod I drew and the actual build is that I didn't have any 18nF caps (to get 15nF in series with 100nF for the Hiwatt mode), but I do have a bag of 33nF caps, so 2x of those in series gets me in the right ballpark (~14nF) for this mod.
#23
Amplifier Discussion / How to setup headphones and am...
Last post by kellanphil - February 10, 2025, 08:50:20 PM
I have OneOdio A70 fusion headphones and I plugged it into my amp and sounds coming out of both the headphones and amp? Both the amp and headphones were gifted so maybe I just need to get better, not so cheap headphones/amp but I'm hoping maybe it's just the settings or something.
#24
Schematics and Layouts / Re: Schematic sites for differ...
Last post by J M Fahey - February 10, 2025, 12:40:37 PM
Thanks for posting, this one looks much cleaner.

There is an error at the power supply: the -12V rail is shown feeding 4558 Op Amp pin 8, it should go to pin 4

Maybe there are others, will check the full schematic later.
#25
Schematics and Layouts / Re: FAL Super 100 4 channel PA
Last post by J M Fahey - February 10, 2025, 12:30:08 PM
You place too much trust in our divination skills ;)

We donĀ“t even know what *Country* you are in, let alone state or province :o 
#26
Amplifier Discussion / Re: Ruby amp from LM386M-1 mod...
Last post by J M Fahey - February 10, 2025, 12:26:15 PM
Just checked your YT video: killer sound  :tu:

Congratulations :)
#27
Amplifier Discussion / Ruby amp from LM386M-1 module
Last post by blackcorvo - February 09, 2025, 01:09:06 AM
Recently I got a handful of those LM386 module boards peeps seem to like turning into fuzz boxes, and got very dissapointed with how they sounded right away, but then I thought "what if I added the input buffer from the Ruby to it?", and went to work.


It's night and day. More gain, better dynamic response, and the "Hiwatt" and "Bassman" mods work as expected.

So, if you have one of these lying around, try adding that buffer to the input and see how it works for you.

For a "full Ruby conversion", on top of adding the input buffer, you can remove C1 on the board and attach a couple wires to it's pads to connect the 1K gain pot, remove the volume trimpot and wire up a 10K volume pot to it's pads, and change C3 from 100uF for a 220uF.
#28
Schematics and Layouts / FAL Super 100 4 channel PA
Last post by Bandito - February 08, 2025, 02:06:54 PM
Hello!

Who can share a schematic for a FAL Super 100 4 channel PA amplifier?
Who would repair/resuscitate it for fun?
https://www.thegearpage.net/board/index.php?attachments/s-l400-jpg.835074/

Mine looks tattier but it makes a noise, is not dead.

Cheers, Bernd.
#29
The Newcomer's Forum / Re: Filtering frequency revisi...
Last post by J M Fahey - February 05, 2025, 12:06:33 PM
Interesting data, thanks.

I see a blast furnace as a tube, one end open, one end closed, with high pressure air injected at the closed end: an organ pipe (or a flute)





the analogy is evident.

It will definitely produce sound, at an easy to calculate frequency.

A 20 meter )(60 something feet) long pipe will produce very high power 4.29Hz, go figure.

Chest pounding indeed.

I was *smashed* by the power involved: an Austrian blast furnace used 8.4 MEGA watt blowers, an old 1919 US one used eight 2000kW steam powered ones.

At the same time, the very low frequency/long wavelength (40 meters) makes it very hard for human ears , separated by mere 30 cm/1 ft or so, to pinpoint source. 
#30
The Newcomer's Forum / Re: Filtering frequency revisi...
Last post by g1 - February 04, 2025, 06:12:50 PM
Quote from: saturated on February 02, 2025, 05:43:03 AMAt night in the small town it got quiet with the exception of an audible hum  :grr
Sometimes I would have the windows open I was in an upstairs room at the end of the house.  This (real or perceived) hum/pitch/monotone frequency tormented me to some end.  In fact I made a few nocturnal excursions around town looking for it.  I would drive around to different areas and shut the engine (slant six 66 Dart) off and sit and try to determine where it was coming from.
Spoiler alert: I never did find it or find out anything.
Tinnitus is not always a ringing and can be a hum.  I have it at 104 Hz.
Most of the time I don't notice, but sometimes it gets bad.

Sometimes the hum can be external though.  For a long time there were people driving around in Windsor, searching for the hum, like you.   :)

https://www.detroitnews.com/story/news/local/wayne-county/2020/07/28/windsor-residents-rejoice-after-mysterious-hum-goes-silent-after-decade/5529975002/