Recapping and Retubing - when to do it
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- Опубліковано 31 січ 2024
- Recapping and retubing are two major service operations that come up when discussing vacuum tube audio amplifiers for musical instruments (guitar, bass, harmonica, keyboards, steel guitar, fiddle, mandolin, etc.) or audio playback (speakers or headphones for home or studio). In this video, Rob from Auburn Amplifiers talks about if, when, and how to go about replacing the capacitors and tubes (valves) in an amplifier to maximize its performance and reliability. Filmed in stereo in a front office at Auburn Amplifiers so that the traffic passing outside the window doesn't sound like waves crashing on a shore. If you like our content, please consider subscribing to our channel. It doesn't cost you anything or expose you to unwanted advertising, but it does encourage us to keep making our cheapo videos in an effort to offset some of the outrageous hooey that seems to have made itself at home in the world of guitar forums in particular. And if you really appreciate our approach, give some thought to your long term equipment needs and consider having an Auburn amplifier made for you. You probably deserve it, and genuinely good gear you can use and enjoy for years and years is a much better investment than a room full of almost anything else. Except perhaps maple syrup.
Great job, your explanation was spot on Rob. It's nice to hear others that actually know what they're talking about.
Very much appreciated. Just don't ask me anything about cooking. My daughters will politely taste a few mouthfulls before asking what time their mother will be home.
Thank you for sharing your experience and sensible, practical information. So much nonsense floating around out there.
You're very welcome.
Great video !!! It's great to hear some honest 'No BS' information for a change. Keep up the good work. It would be good to here more of your advice on preferred manufacturers of capacitors etc. I would always prefer to spend a bit more for quality but in my experience price does not always guarantee quality as there is 'BS' everywhere. Would you be prepared to offer your preferred makes? Keep up the great videos!!!
Thanks very much for your positive comment, David. The subject of capacitors is indeed a can of worms - the answer would fill a book. In general, be cautious about caps that are being marketed directly to music gear enthusiasts as being of a special grade - it's not always the case. Definitely don't let price be your only guide. Good caps do cost more, but an overpriced rebranded or resold cap is not the answer. You're best to work alongside someone who regularly uses a professional components distributor (Mouser, Digi-Key, Newark/Farnell, etc.) and make your searches on those websites based on actual specifications, not colorful descriptions. You may have to buy a few extra pieces of a cap you need, but you'll still come out ahead, especially if you know someone in the same boat. Good luck to you! And be safe!
Having worked in Aerospace I am well aware of Farnell, Digikey and Mouser but cannot always find the values I need. I have a 1965 Fender Vibro Champ which is all original except for one resistor. It still works fine, but obviously the filter capacitor should probably be replaced. I have been looking at the CE Manufacturing version which is expensive but would you say worth it rather than something like a JJ ? @@auburnamplifiers1786
Good post .
I would have liked to hear more on what are the risks of not replacing old electrolytic caps.
Thanks for your very good question. In a nutshell, a failure in an electrolytic capacitor - which can happen quickly - in the worst case can lead to the hasty destruction of much more expensive amplifier components, including tubes, transformers, chokes - even speakers in extreme cases. What's more likely is that your amp's hum will become unbearable and you'll switch it off before anything else is damaged. This could happen in the middle of a gig or a session. This is why it can be false economy to put off a recapping job for too long. This doesn't apply to museum pieces of course - just amplifiers that are actually being used.
Thanks.
I collected Kustom Amps (still have *3) and have been using them on an off
over the years. Id visually inspected and checked uF readings in spec on electrolytics w/ a meter. The big Pwr Caps avg 30 to 60$ a pop and as I don't use the amps much anymore its not worth it to me to sink in the cash.
I power them on every 3 months as I'd heard that it helps.
Fingers crossed.
*I had (3) all Red Kustoms w/ Altec's I sold to the TV show 'GLEE' as they had red ones in their band room.
65DRRI new tubes... new reverb tank.... new rca jk cables' no reverb until turned up to 8 and then is very faint?
I generally agree with what Rob has stated, but to the best of my knowledge and limited testing (older original tubes vs NOS tubes) if the tube emissions are getting low the power output will drop and continue to do so. I think Rob meant to say/explain, that if your amp is working fine or if the sound volume (power and possibly sound quality) from the amp is just marginally down its probably not worth considering replacing tubes just for sake of it... Lastly, within reason (specification, especially in regards to tube rectifiers) I don't think it would necessarily hurt to increase the filter cap capacitance on some cheaper older (the smallest value cap/cost they could get away with) etc Hi-Fi Tube Amplifiers/radios. But like Rob eluded to, due to distortion, sag etc. being part of the sound characteristic of a Guitar Amp you wouldn't want to change the filter cap values on them, even if there is rectifier headroom... unless you purposely want to change the sound signature.
Thanks very much for your insightful comment and support. You're quite correct that tube emissions become reduced as the tube ages. What's perhaps a little counterintuitive is that those emissions won't all fall off at the same rate, even if the tubes are the same age and have seen the same number of hours. This is why it's important to actually check the tubes and replace only the ones that either no longer meet their specs OR fail to provide satisfactory performance (which is not the same thing). It's not like changing the light bulbs on a suspension bridge, where the labor costs might justify changing them all at once. I just don't like seeing people needlessly paying to change their reverb driver or the preamp tubes in a channel they never use as part of a retubing job. Regarding filter cap size in amps with tube rectifiers, I should have mentioned that the tube's spec sheet usually indicates what the maximum safe filter cap size is. I've seen situations where an excessively large cap was installed in an (unsuccessful) attempt to reduce the hum in a single-ended amp, which of course is not being canceled the way it is in a push-pull amp.
@@auburnamplifiers1786 Thanks for the detailed reply Rob, thanks for the extra details on emissions, while I didn't suspect a linear decline you've added a bit of insight into typical emission modes of decline... while I have started "playing" (no playing @ ~400volts) around with tube (hi-fi) electronics I have no personal long term experience (usage) of tube(s) aging . building my own 7868 PP amp but its sadly been on pause for year now...
Sound stuff but didn’t mention the significant of band make end no the paper wax capacitors😊
Do you mean the outside foil connection, and how it should always go toward the circuit point with the lowest impedance to ground?
@@auburnamplifiers1786 yep that’s exactly what I mean ☺️
Hi, this is random, but my amp doesn't work and only shows E3 when i turn it on. Any ideas what i need to do?
All I can suggest is searching online for the error codes for your model of amp. "Error 3" doesn't have a generic meaning, unfortunately. Our own amplifiers don't have error codes.
I see way too many people replacing tubes especially preamp tubes when they dont need to.
Exactly.