old Philips caps from Holland factory and German Roederstien are my favorite for filter caps and cathode bypass caps.
I cut the aluminum cans and put Philips caps inside of 70’s Sprague paper sleeve caps.
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haven’t checked the serial nubmber. it just looks came from between 1964 to 1965. someone added an extra diode on the original one. but the original diode works fine without it. more than one component have replaced at some point.
the output level is too low and I guess it’s the filiter caps. it has 20+20+20+20uf 450v multi cap.
found this nicely built 5F1 with 10″ WGS speaker in Mergili cabinet on Ebay while I was in search of the parts for my first 5F1 build. grabbed it off for very good price and I’m changing the components and wires one by one like the filter caps, bypass caps, speaker wires along with the plug.
I think the speaker wires and Amperex 12ax7 changed way more than the capacitors. I’m waiting for yellow and red Jupiter 0.022 caps as well. an A/B comparison video on youtube was very interesting. and red one looks very close to the original Astron firecracker.
there are few tweed amp inspired cabinets around. and it’s the first cab I like except for the original ones. this cabinet sings with WGS ceramic speaker. I’ve been biased toward vintage Jensen alnico speakers so far. and this speaker changed it a bit
the orange filter caps are Roederstein 33uf 450v which replaced the stock caps from the kit. I didn’t know the limit of 5y3 and was brave enough to put two of them on it. then realized the rectifier was too hot and went to 33+10+10.
the first 33uf right next to the rectifier seems fine so far. I’ve tried on the original 5D3 and 5F1 without an issue before. this very capacitor is one of the caps I trust most
this 5F1 is dead quiet and the filament wiring is a bit different to the original champ. I’m trying to figuring out it. nothing is easy with the electric stuff even 5F1 is this simple.
I’ve got some NOS Sprague black beauty caps 15 years ago and tried it on this amp. I expected something vintage with them. but I’ve learned they are not useful as the coupling caps. they were good as the guitar tone caps. but they dramatically reduced the output volume regardless of the values. realized why my 18watt replica’s output volume was that low 15 years ago today. I’m still wondering why anyway.
[update] the sprague caps I put on this amp had twice high capacitance than the marking. I couldn’t find any 0.02 and tried 0.03 but they actually were over 0.05. higher capacitance changes the frequency and reduces the output volume as I learned from them. and NOS caps need time to break in. they sound getting louder for the last few days
Not sure what I’m going to do with this speaker while I don’t have any SF or BF fender. I remember my friends older than me loved it when I was a kid. even I still remember how the sound was. I saw the same speaker with gray and orange frames. this D120F came from 70’s silver face twin reverb and it’s orange. and it still has the original cone
MR-4BX series has been produced for only a couple of years. the first version came at ’06 and replaced with B-Max4 which was different from previous yoke buggies at ’08.
MR-4BX series is like the last blood of traditional Yokomo to me. and I see the same blood on Jconcepts BJ4.
I have managed to get a nicely used Worlds edition last month. and took some pics with my factory edition. they both came at ’07.
the differences between them are main chassis, F/R shock towers, top deck(s), steering, rear bulkhead, and a few misc parts
MR-4BX Worlds came with a new camber mount which allows only the longest upper rod setup. also the steering is different than previous 2 versions
this new camber mount can be installed on older versions as well
the steerings are quite different. I hope I can feel the difference while I’m running this Worlds edition. but, didn’t have a chance so far.
this steering was introduced with MX-4. prototype MX-4 still had older servo saver. and the first time I saw this was in MX-4 kit.
but the difference is the angle. this steering system on MR-4BX is tilted for better handling.
MR-4BX Worlds came with this 1 piece chassis with 2 extra holes for new steering system. please ignore the stainless screws on the Factory chassis. I’d go back to the black steel screws.
the top deck, now it covers the rear belt. and new camber mount is here
Factory edition had 2 piece top deck like the original version. but the rear piece was improved that older one has clearance problem with the belt
there were a few guys tried this before Worlds edition came. the shocks were moved to the back end of the car.
also they put a camber mount like the front end
the original and Factory edition had same suspension geometry. the shocks can be moved to the back end with this stock mount plus a few tricks
the new aluminum part which holds the the shock tower is changed along with new bulkhead and camber mount
Researchers at the Massachusetts Institute of Technology (MIT) and Harvard Medical School have teamed to develop a novel tattoo ink that can show your body’s health changes.
The novel ink consists of biosensors that react to changes in the tissue fluid and make the skin an “interactive display”. So far, researchers have investigated four biosensors that respond to three types of body information, changing their colors.
As the pH-value increases, the color changes from violet to pink, an increasing sodium content is seen as a bright green under UV light, and blue becomes brown when the glucose level increases.
This animation from a video of the researchers shows how such a tattoo might look like:
Especially for diabetics, a tattoo with ink that reacts to an altered glucose level could be useful. They have to prick their finger with a small needle if they want to measure their blood sugar level – usually several times a day. This procedure can be painful in the long run and can lead to small scars.
You can read more about this innovative technology here: https://www.media.mit.edu/projects/d-Abyss/overview/
My interest in fuzz pedal came from JMI Tone Bender III reissue which belongs to a friend. this pedal has 3 of OC75 glass tube transistors.
And, unfortunately, My Sola Sound Bum Fuzz came with 3 of NPN transistors while OC75 is PNP type. then found this web page with germanium and silicone transistor lists
There are 26 of germanium NPN transistors from the data sheets
2N1302, 2N1304, 2N1306, 2N1308,
OC139, OC140, OC141
NKT713, NKT773, NKT774, NKT781
Black glass tube NPN transistors are OC139, OC140, OC141 from them.
OC75 is like this according to this web page on alltransistors.com
Type Designator: OC75 (PNP)
Maximum Collector Power Dissipation (Pc): 0.125 W
Maximum Collector-Base Voltage |Vcb|: 20 V
Maximum Collector-Emitter Voltage |Vce|: 20 V
Maximum Emitter-Base Voltage |Veb|: 10 V
Maximum Collector Current |Ic max|: 0.01 A
Transition Frequency (ft): 0.1 MHz
Collector Capacitance (Cc): 50 pF
Forward Current Transfer Ratio (hFE), MIN: 55
And, for OC139, OC140 is
Vcb: 20 V / 20 V
Vce: 20 V / 20V
Forward Current Transfer Ratio (hFE), MIN: 40 / 75
I’m going to try OC139. simply beccause, OC139 is cheaper than OC140 on ebay. and I’m wondering how Transition Frequency differences work with Fuzz. I’ll update in a few weeks