MORE Output Issues to FIX | Rift Midweek Update and Q&A |

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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[@MikeM-Colorado]

Thanks for answering my question about populating the board. Your way is definitely easier. I look forward to trying that method.

[@Pete_Harris]

Lovely channel...Subscribed!

[@MyNameWasTecho]

Interesting video as always. A design question for you. When designing an amp, what is your process for selecting the speaker you are going to use in terms of voicing? Do you tend to have a good idea of what you will choose when you are in the planning stage or do you audition a few options as the prototype is nearing completion? Thanks again for the great content and for sharing your knowledge and experience.

[@fuzznerd]

My important amp building question is: what sort of coffee do you drink Chris?!

[@southsidejohnny5624]

“This transformer is unenergised” 😂 I know the feeling mate, I know the feeling. Tbf, I’m even older than that amp.

[@IAmChrisR]

What's the ballpark cost of a transformer rewind? I didn't even know that was an option until I started watching your channel. Seems like the most common option is to replace them, even in vintage amps where that could negatively impact value.

[@januskampmann8307]

My 1964 AC30 has the exact same problem and I have gotten a quote of 200 GBP for a rewind when they use a replacement bobbin. It would be close to double the labor and price if they should use the original bobbin. So I went with the more affordable option. A replacement transformer wouldn't be much less than the rewind, so it was an easy decision.

[@seanblythe9109]

Is there a way we may become a member on a mobile device?

[@RiftAmps]

Not on the IOS app, annoyingly, you have to use the desktop version instead

[@waynegram8907]

What frequencies are you sweeping when using the spectrum analyzer to measure the output transformer? why are you setting the frequency to 25khz?

[@RiftAmps]

I inject a 1kHz sinewave into the amp and measuring the harmonic content at the output. 0-25kHz is audio range so that's all I'm interested in.

[@waynegram8907]

@@RiftAmps That is what I'm confused about if you're injecting a 1Khz sinewave, how are you getting 0hz to 25hz because it should only display 1khz harmonic on the spectrum analyzer. I'm not sure why its displaying harmonics from 0hz to 25khz from a 1Khz audio sinewave.

[@RiftAmps]

@@waynegram8907 any harmonics displayed above the fundamental frequency are generated inside the amplifier. It's that harmonic profile that we're interested in.

[@waynegram8907]

@@RiftAmps But what components or what is generating those other frequencies and harmonics above 1khz and below 1khz?

[@RiftAmps]

You should read up on Harmonic Distortion theory in valve amplifiers :)