Fender Bassman Reissue Part 1 Wrong Output Tubes Wrong Primary Power Voltage Wrong Bias Setting
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- Опубліковано 7 вер 2024
- A fender 59 Bassman reissue in for repair. It has a red plating tube and is need of a re-cap. The more I delved in to this amp the more I found that this particular set of tubes/valves were wrong for this amp. The primary power voltage was set to 230 volts; it should be 240 volts. The tubes had been put in but the bias hadn't been checked. The problems on this amp gave me a chance to do some testing and I ended up making this video on just solving the problems above.
Edit: The original 59 Fender Bassman did have 5881 tubes/valves from the factory. This amp is a reissue and came with 6L6GC tubes/valves from the factory. I should have made that clear in the video. For that I am sorry.
We never got on to the re-cap, that will be in part two.
Friend of mine has a 1961 bassman . I can't afford it but I like it . Very loud , those 4x10s cut thru nicely .
Hello Tom. Yes, the old ones are very pricey. I think I would sooner go for a clone than the PC board version. Although a clone can be a bit pricey too. Thanks Tome and take care.
Nice explanation! I like the old Fender amps with the bias balance circuit (output tubes matching). That way you can use tubes that aren't perfectly matched. Also, I've seen amps where the resistance on the 2 halves of the output transformer differs by a fair amount and the bias balance circuit can compensate for that. I usually add a bias trim pot to the bias balance pot (after lowering the value of the bias resistor to ground), so you have the most flexibility in dialing in the bias.
Hello Michael, thank you. It makes you wonder why more guitar amps don't have a balancing pot on the bias. It makes sense. I have never worked on an early Bassman. We don't see many of them over here. What few there is are in collections. A good idea to have the trim pot with the Balancing pot. Take care Michael
@@vintageguitaramp_guitarteacher I know Fender amps were rare in the UK up until the mid 1960's due to the import ban after WW2, but I would have thought they would be more common these days. I now have 7 of them from the '60s and '70s, the most recent a Vibrolux Reverb I received on Monday. Ordered parts for a recap and other maintenance yesterday.
Excellent video. What a perfect opportunity for instruction on proper tube checking and biasing. The best UA-cam I have seen on this subject yet. Kudos..to you for seizing the moment..!
Hello David. It's good to hear from you again. Thanks you for your kind words. I hope you are well. take care.
Quick, logical and effective diagnosis and correction. We’ll done, and thanks for the video
Hello Scott, thank you. Thanks for watching and take care.
I've learnt more from you Martyn than any other tech who has a channel on You Tube with the exception of Stuart at Berkshire Amp Repairs. Showing a repair or mod but leaving out even a small piece of the puzzle or not joining the puzzle up completely can be quite a dodgy thing to do for amateurs like me. You do not do this and your videos are both entertaining and very informative with the bonus of some great guitar playing at the final testing stage. I've always had a soft spot for the 59 Bassman which is really where it all started as in the 1950's and early 60's these amps were used for PA, bass guitar, lead & rhythm guitar, sax and piano etc. A real jack of all trades and generally very reliable with great sound reproduction. Ray Charles swore by them for his band. (I'm giving my age away here 😅).
Hello Pete, thanks for those kind words. @stuartukguitarampguy5830 is a great tech. He's good with the Solid State amps too. Yes, I think the Bassman is the most iconic amp and will remain so for ever. Although this one a more modern one, I really like it. Thanks for supporting the channel Pete. take care.
Worth noting that the original 4 x10 Bassman did use 5881 tubes, running well above their specifications, but back then they had tough-as-nails American-made 5881's which were made to military specs.
Hello, good to hear from you again. Those 5881s were JAN tubes. The boxes were in the bottom of the amp. The dates on them are December 86. So they were bought as new old stock. They are 6L6 WGB tubes. Would you class these as good tubes?
@goodun2974 - JAN Philips tube is actually a military spec American tube. The last runs were spotty and circulating
That might be true, but do we know what brand or manufacturer was of the original 4x10 Bassman output tubes…? It could make a difference.
truth
i should have pointed out in the video that the amp was a Bassman reissue. The bias circuit in the reissue amp wasn't right for the 5881s. The sweep on the trim pot ran out before you could get the tubes to run cool enough at 70% of 23 watts. Taking the pc board out just to change the bias circuit wouldn't be a great idea. I didn't make that clear enough in the video. I have amended the title to reissue though.
Fender, Boeing and many other ones US reputable companies have been now managed by a ‘bean counters’ instead of engineers. The quality went ‘south’ as soon as those accountants took a power.
Hello. I think most of the world is being managed by bean counters now. It's sad, but at least there are still plenty of old vintage amps left to enjoy. Thanks for watching and take care.
Bassman Reissue not a real one BTW. You can totally use a 5881 in that amp, probably better because they draw less current and get lower volume breakup. Those Phillips ECG if I am not mistaken are ruggedized 1970's tubes or valves for you in the Monarchy. You can't tell until you check the bias actually if they are messing anything including themselves up .(edit) After I watched I see you are doing what I imagined I might do. I just don't care for any tube/valve amp with a PCB but that is just my humble opinion.
Hello, yes, not a real one. I should have made that clear in the video. I should have also made it clear that the original 59 Fender Bassman came from the factory with 5881s. I have amended this in the title and description. 59 Bassmans are rare in the UK. I have never worked on one before. The problem with this reissue is the bias trim pot didn't have enough sweep to adjust the bias down cool enough for this set of 5881s. I did show that in the video. It then means that the board will have to come to change the bais circuit. So this particular set of tubes were not right for this amp. Of course some 5881 tubes draw more current than other 5881 tubes do. I don't think I made that clear enough in the video either. So I am sorry for that. Thanks for pointing that out. It's fair and constructive. Thanks for watching and take care.
😄😎 great video
Thank you. Take care.
@@vintageguitaramp_guitarteacher You are welcome, I learn/you instruct me, as to how to and what to look for as I repair my 15 amps mostly tubes amps . Thanks again from the USA
so sad how badly made these modern fenders are, they took pretty much perfect proven designs and ruined them to save a few bucks.
Hello. Yes, when you look inside this amp, it wouldn't have taken much time to put an eyelet or turret board in it. Some of the more modern Fender amps are a terrible design. Thanks for watching and take care.