Fender Bassman 1965 Circuit AB165

Fender Bassman 1965 Circuit AB165 - Amp Demo

Рет қаралды 33,306

5 жыл бұрын

I've been working on this amp for an extended period as I'm able to carve out some bench time. This amp came to me with some broken power tubes, microphonic preamp tubes and some low plate voltages. It has new Sprague Atom filter caps, metal film dropping resistors, new Sprague bypass caps for the normal channel, re-wired filaments, metal film resistors on the output tube sockets with an added 1 ohm to ground for biasing. All of the potentiometers were cleaned as well as the brass grounding plate inside the chassis. There were some changes to the bias circuit to make it more like a Pre-CBS Fender circuit and a new electrolytic in the bias.
Other changes included removing some broken and microphonic ceramic capacitors one broken resistor and a couple suspect resistors and reflowing solder.
PLEASE NOTE: The pictures in the beginning of the video are taken from several different times throughout the work and do not reflect exactly what is being discussed before the demo.
I'm providing a link to infomration I used to guide my changes. I didn't do everything the link discusses. Bypass capacitors in the Bass Instrument channel were left in and the Deep switch on the Bass channel doesn't work and I didn't bother replacing it. Essentially the Bass channel was left alone. Here is the link:
acruhl.freeshell.org/mga/main/...

Пікірлер: 111

@JohanSegeborn 3 жыл бұрын

Sounds great!

@bbmade 3 жыл бұрын

I appreciate that coming from a tone hound like yourself. You have great videos and great tone sir!

@Donfleebie1 Жыл бұрын

My Dad bought me a brand new 64. I stupidly traded it for a new Randall RG-80 Combo in 1980. I still have my 1973 SFTR, but back then we didn’t know what we had. Just like a couple of muscle cars I wish I still had.

@bbmade Жыл бұрын

I hear ya. I think most of us have those types of experiences letting something go and regretting it. I sold off a Gibson Howard Roberts my dad surprised me by paying off the layaway. Now that he’s gone, I really regret selling it as a young broke kid trying to figure out life.

@LateNightYinzer 2 ай бұрын

It's so true. Just don't even know what you have till it's gone. So many guitars and amps I should've just kept. Keep chasing the tones but don't sell the ones you once chased before, you'll want them again someday!

@jtn191 4 жыл бұрын

Great video & amp 👍

@bbmade 4 жыл бұрын

jtn191 - thanks!

@Tonetwisters 4 ай бұрын

Not a thing wrong with that amp! Sounds real fine!

@bbmade 4 ай бұрын

Classic Fender tones.

@kravensoda6038 5 жыл бұрын

Sounds good BB... & niccce rippin man. Xheers! likd 31

@bbmade 5 жыл бұрын

Hey Soda - Thanks!!

@danh.8490 2 жыл бұрын

Installing a trainwreck type 3 post PI master volume works great in these amps, I used a PEC 1 meg pot & put it in the ground switch hole. I get best results with a 12AX7 PI instead of the stock 12AT7. Leaving the PI tube shield OFF smooths out the treble when using the MV. Converting to the AA864/AA165 power amp layout also helps alot. Sozo blue signal caps sound similar to the old blue molded capacitors & are great replacements.

@bbmade 2 жыл бұрын

Thank you for the info. I have a couple more of these and might try that on one of them.

@fivewattworld 5 жыл бұрын

Hey BB, Nice video and nice old amp. I didn't know you did this much amp work. As you know I've done some amp building but you seem to know what you're doing (where I decidedly am a build by the picture sort of guy.) Good to see the astrons hadn't been plundered long ago. There is a bit of magic there in those in my experience.

@bbmade 5 жыл бұрын

five watt world - Thank you! Amp turned out pretty well in the end. I’ve been fascinated by tube amps for a couple decades while doing guitar repair and building. It’s been the last five or six years where I’ve finally jumped in the deep end. Lots of reading, studying, soaking up info anywhere and everywhere to have a better understanding of them. I feel fairly comfortable with Fender designs because that’s what I’ve always played. I am nowhere near an expert on amps. I know many people who have forgotten more than I’ll ever know but I get obsessive about these things. Some new adventure every ten years or so. More amp videos in the future for sure!

@fivewattworld 5 жыл бұрын

@@bbmade Do you know the books by the Canadian guru O'Connor? I don't know much but I still found them very readable and an incredible wealth of information.

@bbmade 5 жыл бұрын

@@fivewattworld No I haven't heard of those. There are lots of .pdf books from the early days of radio and books the Navy puts out on electronics which are a great place to start. The amp technology that I'm interested in was fairly ironed out in the 50's and 60's. I have a bunch of other books as well and am hoping to grow into solid state and pedals in the future as well. If you have any you'd recommend I'm interested!

@fivewattworld 5 жыл бұрын

@@bbmade I'll get the specifics on the O'Connor book. He invented power scaling. Search under "london power". I think that's what he called it.

@kosmicwizard 3 жыл бұрын

@@fivewattworld Mark Stephenson builds amps with this technology in them! His builds are killer, Keith. If your ever in Chicago try the 40 watt Stephenson combo that's been on reverb for years. Cheers.

@bluesslider76 2 жыл бұрын

Great video.

@bbmade 2 жыл бұрын

Thanks for the comment. Glad you liked it.

@resonatemobile3398 3 жыл бұрын

Love the up close view of the amp controls. Great video overall, although I would have loved to hear the amp cranked to like 8 or 10!

@bbmade 3 жыл бұрын

Thank you! Yes I did realize the error of my ways not cranking it wide open. I have a couple more of these to fix up so next time we’ll be sure to do that.

@mentholdeathray 4 жыл бұрын

I love my 66. It was completely blown up when I got it and a good friend restored it for me. He built it to have very much a Marshall vibe. Also the ground switch on the rear is now a boost. Thing absolutely rips! Jumping channels and cranking it makes for some sweet overdrive tones

@bbmade 4 жыл бұрын

Awesome, these are cool amps and the Marshal vibe is a cool mod. Thanks for the comment.

@bbmade 5 жыл бұрын

PLEASE NOTE: The pictures at the beginning of the video were taken over a period of time that I was working on this amp and do not reflect exactly what is being said by me as the video starts. This is a demo video of the amp and not a "how to" on anything. Don’t work on amps if you don't understand the safety considerations involved.

@leonardo.rafael 5 ай бұрын

When I use humbuckers (14.7 ohm) the volume increaases and the tone is not so clean. So I try in the jack number 2 which is for a more strong signal instrument, but it loses high frequencies. I was concerned with mine being a little noisy, but I heard yours sound similar even you have changed a lot of old components and using humbuckers. Its nice to know that. Thank you for your demo.

@bbmade 5 ай бұрын

Thanks for the comment. I was standing right next to the amp with lights all around me so it probably made it a little more noisy. This video was quite a few years ago so the work isn’t fresh in my mind. I wouldn’t be overly concerned with a little bit of noise. If it makes noise with you turn the controls the pots could need cleaning or a coupling cap might be letting a little DC through which is worth having it looked at.

@regiizii9559 5 жыл бұрын

This is the sound I've been looking for. In all seriousness, Do you know if these mods can be made for all AB165 or it is specific to this year of production 1965? I'm a looking at a really clean 1966 blackface bassman and was wondering if I could get this tone with the mods. Great work, it sounds fantastic!

@bbmade 5 жыл бұрын

Thank you! Glad you liked it. The changes to this amp were fairly simple to get it more like earlier Bassmans. There’s a link in the description to what I used as a reference for the changes. I would guess a ‘66 could easily be changed and the later Silverfaces would be too but might require a few more to get it to be the same. I’d have to look at schematics to see what other changes they made in the Silverface era. The AB165 from that era are pretty easy to come by and won’t break the bank. I have two more that need work but check Reverb and you can find them in the $800 range. If they have a lot of original caps they’ll benefit from getting serviced.

@willdenham 2 жыл бұрын

I have the highly underrated red headed sister amp, the bandmaster. It sounds amazing cranked with a Les Paul. It's, like the bassman, as beefy as my old Marshall was.

@bbmade 2 жыл бұрын

Very cool. I have a very crusty bandmaster chassis and an even crustier head cabinet to fix up. Look forward to hearing that compared to a Bassman. Thanks for the comment

@willdenham 2 жыл бұрын

@@bbmade Mine had been stored in a damp basement for 18 years. Took it to a local amp guy, he recapped it and I think that was about it. I dimed it in the studio space through a used cabinet I picked up for 100 bucks, in the company of my frontman and both our jaws dropped. It's the kind of gain we both dream of. It's like the thing grew teeth while in storage.

@willdenham 2 жыл бұрын

@@ErikThomasMusic Funny you mention that, I was considering switching the OT on my 65' for a Bassman OT. I thought it would tighten up the low end. I have a 1959 SL Plexi build coming soon so I think that will provide what I'm looking for.

@willdenham 2 жыл бұрын

@@ErikThomasMusic The 63' must be the tuxedo tolex, correct?

@willdenham 2 жыл бұрын

@@ErikThomasMusic I think it's also interesting how you changed out both OT and PT's on those amps. I have never heard of that.

@jim3232 5 жыл бұрын

That sounds absolutely excellent. I am considering getting an old bassman head but so many people tell me it will be too loud. With a 1x12 cabinet, will I be able to get those tones at home at relatively low volumes?

@bbmade 5 жыл бұрын

Hello Jim Bo - I’d have to say you can’t get those tones at a low volume at home. It was pretty darn loud when I got it up to around 5 on the volume. To my ear that head at low bedroom volumes is pretty uninspiring but as you turn it up magic happens. I’d look to something lower wattage with maybe two channels. The Zinky Velvet amp I have sounds killer at lower volumes. A good Blues Jr with an overdrive could work well too.

@jim3232 5 жыл бұрын

@@bbmade Thanks, BB

@aaronbrooks3913 5 жыл бұрын

You can with an attenuator. I would recommend dr z air break attenuator.

@bbmade 5 жыл бұрын

Aaron Brooks - That’s true. I’ve had mixed results using them and it’s an additional cost but certainly an option. Thank you for the comment.

@jazzzfer 4 жыл бұрын

@bbmade That strat sounds very cool. What pickups are and that ? and what guitar is it ?

@bbmade 4 жыл бұрын

Fernando Franco - That is a guitar I made and it has Lollar pickups. I think that guitar has the Lollar Blackface staggered pole piece set. Thanks for the comment!

@jazzzfer 4 жыл бұрын

@@bbmade thank you. That sounds great.

@fullstop213 4 жыл бұрын

Very nice, all the way around! I'm hoping that the resistor used in parallel with the 8 ohm speaker was a typo at 4 ohms, as that equivalent resistance is 2.7 ohms. (2) 8 ohm resistors in parallel = 4 ohms.

@bbmade 4 жыл бұрын

Yes the actual resistance reading of the speaker is less than what it’s labeled as. May very well have been a typo. Head is 4 ohm output, speaker was 8 ohm so I used an 8 ohm resistor across it so the amp was “seeing” 4 ohms. Good catch! Thanks for the message.

@joseceraia 3 жыл бұрын

@@bbmade One step up or lower does not harm anything .

@bbmade 3 жыл бұрын

@@joseceraia Perhaps but it does change how it sounds. It’s my understanding you can go up in the impedance without issue but going below works the output transformer harder. I would need to do more homework on it.

@joseceraia 3 жыл бұрын

@@bbmade Indeed, it can change the tone, but if it is audible is another question.Until now, I could not hear any change by normal playing. I tried it several time while working on amps.The impedance of a speaker changes very fast the higher the frequency. If you change 2 steps, ex: from 4 ohm with 16 ohm speaker or visa versa that is something else.

@bbmade 3 жыл бұрын

@@joseceraia Thanks! It’s been quite a while since I worked in that amp but I remember not liking what I was hearing and then added the resistor on the speaker to get close to what the amp normally had and it changed quite a bit. Again, it was quite a while ago so I’m working off memory. Thanks for the comment!

@Somnospeed 2 жыл бұрын

This amp turns Devine after turning it past 5 and up. Too bad this video never goes 4. Would have been a perfect video.

@bbmade 2 жыл бұрын

I have four more of these heads to fix up. I’ll goose the next one for sure!

@NnNn-eq5hr 3 жыл бұрын

It's a very cool guitar! What brand and what model?

@bbmade 3 жыл бұрын

Thanks! It’s a guitar I made and refer to it as the BB-1. Semi-hollow/thinline S type guitar. I’m not actively selling instruments right now so I tend not to mention much about them.

@mickgentry8128 Жыл бұрын

What valve are you using for PI?

@bbmade Жыл бұрын

The amp sold a long time ago. It would have had whatever style preamp tube the schematic called for but I don’t know what brand. I’m getting better at documenting the work as a more permanent record but, this was before I tried to do that.

@richardclintondavis2831 5 жыл бұрын

Ab 165 to me is the best bassman circuit

@bbmade 5 жыл бұрын

Thanks for the comment. It’s a fine sounding circuit to be sure. This particular amp sounded a lot better after the servicing. Most of that was getting rid of the leaky coupling caps but a few small changes as outlined in the video description (link) helped it as well. I really enjoyed the end result.

@richardclintondavis2831 5 жыл бұрын

Yeah had the same thing done about 10 years ago mine has been rocking 51. Years now🤘🤘🤘

@nickbracamonte 5 жыл бұрын

Should have janmed the bass channel too it has 3 gain stages vs normal 2 I believe

@bbmade 5 жыл бұрын

Nick Bracamonte - Yeah, that’s probably worth while showcasing. The bass channel itself was pretty uninspiring and I didn’t want to do any mods to it. Some people will do a Marshall type mod to take advantage of that channel but I just wanted to get it sounding good and move it along. I have two more so maybe I’ll dive deeper into it in the future. Thanks for the comment!

@jegr3398 4 жыл бұрын

On the AB circuit both channels have 3 I believe

@fanoboss Жыл бұрын

i love ab165 's

@bbmade Жыл бұрын

Yeah they can be great. I just finished and AA864 and am currently working on another AB165 with one more 165 waiting in the wings. Hopefully I’ll have time to do a comparison of the 864 to 165.

@Hillelfan02 2 жыл бұрын

So because of the mods you did does that mean the normal channel is like the AA864 circuit?

@bbmade 2 жыл бұрын

This is a bad answer but the reality is I don’t remember the specifics of that amp. I used some information I found online to change a few things but it wasn’t full spec to the AA864 from what I do remember. I’ve started documenting work on amps in more detail but this one wasn’t detailed in any notes I have. Sorry about that.

@Hillelfan02 2 жыл бұрын

@@bbmade no worries I’m just asking because I want to buy a bassman and I played through one and the sound wasn’t bad but it can be better I think if I mod it to the AA864 circuit, I’ve read a bunch about some things you can do but I’m trying to figure out if you can fully convert it

@bbmade 2 жыл бұрын

@@Hillelfan02 Well, I have three more to do so I plan to do more homework ahead of time. If you get one an mod it, drop a comment to explain how you like it. I’ll for sure do another video on the next one. A few people pointed out that I never cranked this one wide open. That will happen in the next one.

@Hillelfan02 2 жыл бұрын

@@bbmade I will totally let you know also have a short video of me cranking a bassman to 10 with my strat on 10 with greenbacks it was glorious but the phone sadly doesn’t capture the whole of it but your welome to check it out

@atwozeek 4 жыл бұрын

Where did you get your parts?

@bbmade 4 жыл бұрын

atwozeek - I get some parts from Mouser Electronics and CE Distribution which is the wholesale side of Antique Electric Supply. Thanks for the comment.

@atwozeek 4 жыл бұрын

Do you have a parts list for this project? Just picked up a 12/ 1970 silverface with ab165 circuit. All original Mallorys i believe Thanks

@bbmade 4 жыл бұрын

atwozeek - Sorry I don’t have a list. Check out el34 World. Lots of schematics and layouts so it’s pretty easy to figure out what a particular circuit would need for parts. el34world.com/charts/TubeAmpSchematics.htm

@jegr3398 4 жыл бұрын

Cmon crank that thing up to 10

@bbmade 4 жыл бұрын

Je Gr - Dang The sad thing is it didn’t really occur to me. I was testing it out after all the work was done. I have a few more of these and next time I will crank it open!

@jegr3398 4 жыл бұрын

@@bbmade Right on, some of those big blackfaces sound surprisingly good cranked, I've got a 64 Tremolux that sounds pretty damn good. Cool amps!

@bbmade 4 жыл бұрын

Je Gr - Yeah I need a dedicated speaker cabinet set up to test amps but will definitely crank up the next one for a video.

@jegr3398 4 жыл бұрын

@@bbmade Good idea, so you don't blow the original speakers. I blew one of the original ceramics in my Tremolux cab, but I replaced it with a reissue alnico Jensen out of my Brownface Concert. The Tremolux sounded even better after that.

@stephenmcgraw3610 3 жыл бұрын

I have one also how can i tell what year it is

@bbmade 3 жыл бұрын

EDIT: Good catch by @kosmicwizard. I was thinking of the AA 165 circuit in the following comment. Thank you! The AB 165 was made in a somewhat short window of time if I remember right. If yours has the original transformers you can look up the date code format. The first three numbers are the manufacturer and then there is the week of the year and two digits for the year. Potentiometers, capacitors etc have these sorts of date codes too. Hope that helps! Check out this link for some info too: fenderguru.com/amps/bassman/

@kosmicwizard 3 жыл бұрын

@@bbmade ab165 were from 65 well into the silver faced years.

@bbmade 3 жыл бұрын

@@kosmicwizard - Yes I was referring to the AA 165. You are correct sir!

@kosmicwizard 3 жыл бұрын

I'm not 100% sure that turning the bass channel in one of these into a tweed circuit is the same as the Marshall mod people are talking about, but since the JTM45 is a made in UK Bassman (just like a Traynor YBA1 is a Canadian made Bassman) they are probably really close! Why not try one of these kits when you get the next one up on the bench? No affiliation whatsoever. Cheers! vintagefenderamprepair.com/products/ab165-to-aa864-plus-tweed-preamp-for-blackface-ab165

@bbmade 3 жыл бұрын

I originally found a site talking about mods for this version of the Bassman and they mentioned the AA 864. I have at least three more of these heads so I’ll do some homework and ponder doing something different on the next one. Thanks!

@kosmicwizard 3 жыл бұрын

@@bbmade i think the "plus tweed preamp" part goes in the bass channel side of things. Then you get the best of both worlds dirty tweed and black panel cleans in the same amp. Then you can use an AB pedal to switch between clean and dirty parts during live songs.

@bbmade 3 жыл бұрын

@@kosmicwizard I haven’t looked at any in depth mods to these amps. I’d have to re-watch the video to recall what I documented there. I’ve heard of people modding the normal channel for a Marshall” sound because there’s an extra trios to take advantage of but I could be wrong. Haven’t looked at the schematic in a long time. I also need to look at the 864 schematic and revisit that website I initially looked at. I’m always open to learning more and gaining knowledge from people that have worked on amps. Thanks again!

@papawx3 5 жыл бұрын

Tony, is that you?

@bbmade 5 жыл бұрын

No sorry, no Tony here.

@xion8309 5 жыл бұрын

Aren't you killing that amp without a cab?

@bbmade 5 жыл бұрын

Thanks for the comment. No, not hurting it at all. It’s a 4 ohm output and I ran it to an 8 ohm speaker. Then I put a 4 ohm 25 watt resistor in parallel with the speaker. You wouldn’t want to run an amp into a lower impedance.

@bbmade 5 жыл бұрын

Oh, and the speaker I’m using is in the cabinet on the workbench just in case that wasn’t clear.

@bloomi5387 4 жыл бұрын

Wait the whole video hoping you dime the godamn amp! Just crack it!

@bbmade 4 жыл бұрын

Hot damn, I guess I better get the next Bassman head fixed so I can let it fly wide open!

@crumb0000 3 жыл бұрын

uh, if you retain the ajax signal caps...put them back in. These orange things change the sound too much..they pass too much signal, way too much.

@bbmade 3 жыл бұрын

The coupling caps to the output tubes? I wouldn’t want old capacitors there? I’ve never heard that about orange drop caps but appreciate that info. Sounds like I have some more homework to do for future projects. Thanks for the comment!

@crumb0000 3 жыл бұрын

@@bbmade you heard wrong, or rather, you do now. Signal caps have a sound, and there's a reason those ajax sell for 50 bucks a pop. Do the research with your ears, orange drops are great caps, really great, too great, they pass highs and lows you don't want, this de-emphasises midrange. They don't wear out, they're just a roll of plastic over a roil of thin aluminium foil, then rolled up like pastry. Some poorly made ones like the tweed Astrons fail because they were just low quality, the leads disconnected from the foil.

@bbmade 3 жыл бұрын

@@crumb0000 - I will try some different caps in that section on the next Blackface Fender. I’ve compared a dozen different caps in the context of guitar tone controls. The differences are subtle nearly imperceptible but that’s not the same. There’s an aspect of psychoacoustics that comes to mind in any of these discussion. Does an orange drop versus another cap in the coupling to the output tubes counteract all the other tolerances and drift of components over decades? Debatable, opinions vary and I’m always looking to people with more experience to inform my processes. I appreciate your insights.

@crumb0000 3 жыл бұрын

- that 2 percent difference becomes 25 percent the longer you play. A beginner wouldn't tell the difference, someone who has played for decades will avoid an amp like the plague for that 2 percent. To be clear, the difference is only ever 2 percent..but it SEEMS much bigger to a keen ear. In reality, most guitarists can't hear shit differences in anything, they hear distortion, or clean, and that's about it.

@bbmade 3 жыл бұрын

@@crumb0000 - Well, again, I appreciate your insights and all things considered it’s a quick slope down the rabbit hole of “tone”. Insinuating people’s ability and generalizing players to say they can’t hear “shit” differences alienates people. I’ve played a long time and always wondered what makes one thing sound “good” or “bad” and what on earth I think is good. To get back to the original comment, the coupling caps to the power tubes need to be reliable. The signal chain is influenced the most, early on and yes it all matters but to what degree those caps make or break an amp is up to the person working on or making the amp. I’ll try different caps there on the next Bassman but I won’t put old caps there. The fact they fetch $50 a cap doesn’t mean they’re the best, it means people are willing to pay $50 for an old capacitor in hopes it makes their amp sound better. It might, or it might not, the caps might leak or they might not. You don’t want DC leaking onto the grid or worse, failing completely letting 220VDC onto the grid in this particular circuit. Thanks again for the comments. I try to do the right thing on all these guitars and amps so wherever I can gain some knowledge it’s all the better.