What do you think about this? | Rift Midweek Update and Q&A |

Apologies to channel members, I forgot to include the scrolling credits!
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PLEASE NOTE: This is not a tech channel, but simply a show-and-tell. It is not designed to give advice and support on vacuum tube amplifiers but to show what I get up to each week in the workshop.
I deliberately keep tech talk to a minimum, or at least to a point where it’s understandable to the casual viewer. There are other channels more suited to that level of detail.
I do not do reviews, either paid or unpaid. My opinions are entirely my own and do not represent those of others.
All comments are welcome but those deemed unhelpful, rude, inappropriate, or unsavoury will be reviewed and possibly censored.
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Updates
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EQUIPMENT I USE
Wire Strippers - uk.rs-online.c...
Knipex Snips - uk.rs-online.c...
Oscilloscope - uk.rs-online.c...
Signal Generator - uk.rs-online.c...
Soldering Station - uk.rs-online.c...
Chisel Tips - uk.rs-online.c...

[@lamppostwillie]

Calling someone lame on the internet because of a trivial matter. Lame. Great work, Chris.

[@MikeM-Colorado]

That 5c3 is a beauty. First thing I noticed was most or all the resistors on the board are 1 watt. Overkill 😂. Excellent demonstration of the wattage calculation. Thanks!

[@chrisgmurray3622]

Very good. Chris, and others,... I hope we won't start being rude to someone for being rude, because it's easier to be polite anyway, and the buck stops at the person "taking offence", rather than being re-charged and passed on... a good time for a short circuit!

[@jjsant3250]

Fender added a ~320pf cap from grid to cathode on the 6V6 in the AB764 version of the Vibro Champ to stem that oscillation. I took it off mine since it can be considered a “tone sucker” and got the oscillation. I then changed the grid wire to shielded and it resolved.

[@jmormino5465]

Very well done. Nice finesse Always love a little math refresher

[@bambule5268]

Great video. Nice to see those fenders working perfectly again!

[@johnburns5783]

Put a blanket over the car windscreen 😂😂😂

[@andypendlebury6445]

Love those old fenders, what a treat seeing those, so thanks for sharing. The vibrochamp sounds delicious! As the OT on that Fender is a non standard replacement? Could you go into how you got those values? Many Thanks ✊

[@giulioluzzardi7632]

Keep the shades handy, don't know why but it makes me trust your judgement.

[@midnighthour4299]

Love the way you handled the cranky comment, it was a bit uneccessary, could have been phrased as a question. Well done.

[@chrisgmurray3622]

Rumour has it that Leo Fender was famous for being frugal and using up whatever parts were lying around to make up finished items and sell them. At one point, even though Leo was no longer in charge of Fender, but staying on as advisor to expedite the change into new ownership under CBS, Fender put out Telecaster guitar bodies with Strat necks (Tele Special). This was typical of mist engineering at Fender Marshall or anyonein large scale manufacturing before CAD CNC machines etc. Parts in Gibson Les Paul Standard PAF humbuckers were used whether the bobbins were white or black, contrary to popular myth that thete was some special tonal differences. They simply used combinations of identical but sometimes differently coloured pickups in what has been called "zebra humbuckers. Just using up stuff you have; normal practice " back in the day".

[@nigeltrueman5931]

Great video. Once again I know this is not a technical channel (but as I said before your so good at explaining things :-) I was interested in the choice of capacitor size for the parasitic oscillation, what made you choose that value?

[@JEmilioJNava]

Greetings from Mexico City.

[@David-gx9lh]

Thanks for going over the maths for resistor rating Chris, that was really informative and definitely not lame! On a different topic, do you ever fit master volumes to your Princeton Reverb-style builds? I tried a post-PIMV on a 6g3 Deluxe build, and though it has its uses it seem to pull a fair bit of the grit from the tone. I know the PI is different, but is there an effective solution for a cathodyne PI amp? Cheers, David

[@planetcaravan8044]

Everyone loves a line Out

[@planetcaravan8044]

Lame

[@jamesunderhill1603]

I must admit i've often wondered why no one just used one type of wattage resistor, now I know. 👍👍

[@kmetal83]

I really enjoy your channel. You're not a pompous ego-maniac like some other KZbin techs/builders. Cheers

[@danielsaturnino5715]

Am I wrong assuming that a proper watt rated resistor (or a bit larger to ensure normal working conditions lifespan) would prevent transformer damage by going open if say a valve goes shorted?

[@IainThacker]

Great idea about the line out, having that or, even sweeter, a balanced DI is really helpful for us gigging bassists. That said, something like this would be a home practiice tool for me - not loud enough for most of the gigs I play. I run a 900W Class D amp into a 1200W Barefaced cab - ultra light setup. I get my sounds from a Quad Cortex - ultra useful when you're on a festival gig and have to get on and off quick! I've actually carried the whole rig, including bass, onto and off a stage in one go! Question though... People often comment that "class D watts" and "tube watts" aren't created equal. From a maths persepctive a Watt is a Watt - the calcs are nicely laid out in this video - thanks! What do you make of that debate?

[@atech9020]

I have a thing about Carbon Comp resistors..... I don't like them. The " Mojo " of them has no value if the " Mojo " disappears when the temperature exceeds 75*F, the humidity goes above 20%, and the voltage that day is 5v higher than normal. CC resistors are just not worth the trouble. I doubt a person could succeed in a double-blind test to tell which of three resistor types is which. I prefer Metal Film for stability, life span and tolerance. Carbon Film is a second best, because you can't argue with them. Carbon Comp though, hard pass...

[@mbosch1970]

Hi Chris, great video again!! One question with the Vibro Champ, I noticed that you didn't change the speed in the sound examples and that the speed at 1 already was quite substantial (at least from what I can hear from the video)...is this typical for this model and what is your preference on the range of speed on Fender amps (I seem to remember from Uncle Doug video's that you can change the speed an intensity of the tremolo by changing the capacitor values in the tremolo circuit...is that correct?)...

[@TwangThang57]

You made chicken salad from chicken sh*t !!

[@MichaelSmith-rn1qw]

The alnico speakers Fender installed in the Vibro Champs were not very good even when new. I built a 2 x 10 cabinet for my Vibro Champ and installed a 1/4" speaker jack so it can also be played thru my 2 x 12 or 4 x 10 cabinets. It is an entirely different amp through bigger/better speakers.

[@marktierney3938]

I always see people recommending to bias amps around the 70% plate dissipation mark. The 5c3 you said was around 100%, is that an acceptable bias setting because it's cathode biased? And does the 70% rule only really apply to fixed bias amps? Apologies for my noob question.

[@RiftAmps]

70% is often quoted as being the correct bias point for a fixed bias amp because the assumption is that hotter is better. However, the acceptable bias range is 50-70% and not every amp sounds/performs best at the upper limit. It's why I bias using an oscilloscope to check the actual performance of an amplifier, becuase that's what actually matters. Cathode biased amps are usually set to around 100%, yes.

[@marktierney3938]

@@RiftAmps thanks for the reply, makes sense!

[@LollygaggerFX]

lol….. ok I repent. Lame….. was not a nice thing to say (Prolly cranky when I wrote it) My point was I usually don’t get too critical about wattage of resistors WHEN you are “NOT” exceeding the rating. I often will go up to a 1 watt if I don’t want to deal with 2 different wattage sizes. Again I apologize for being rude. 😊🙂

[@DanielBobke]

I greatly enjoyed your nursery school teacher voice for the learning section at the end for @LollygaggerFX. Clearly the soothing voice should enhance his learning 😉

[@chaosin73]

What ( no pun) is the difference in cost in the 1W resistor and the appropriately sized one?!

[@petercornell2002]

Lame???? Sorry Sean, we all have our opinions! Another good vid, thanks Chris

[@riley0187]

some of us like a flubby bottom end

[@jupjuck]

Some of us have homes to go to.

[@seanblythe9109]

Big Joules for the lame comment. Go maths!