AC30 Comparisons - TB/TBX Pros and Cons

[@luthiervandros]

Lyle, never ran across you on any forums, though I realize you've been a big contributor at TGP. Just wanted to give you a shout-out. A lot of techs make income based upon videos like yours, or off the sweat of your brow. I want to thank you, bc you've helped me streamline my pre-roll intake with incoming repairs. I do homework days before to help me hit the ground running. Your TB/X series was very helpful to me, even as an Electronics Engineer. The biggest compliment o could pay you is to state that you are at engineer level in your analysis and troubleshooting approaches. Thank you. FrankD @ Forgotten Gear Restorations

[@PsionicAudio]

Thanks so much Frank! That means a lot.

[@PsionicAudio]

At one point I say "low pass" when I meant to say "high pass." Sorry about that.

[@richclayton5785]

I don’t know how I missed this series a year ago, but I am finding them very helpful in that I have a great deal of interest in the amp you are attempting to get into production. It’s now more clear where you are going with your amp.

[@lordhonksworth7701]

Interesting video, thanks for going over this amp - I still have one of these, bought it in 2001, at the time I knew nothing about Vox amps but knew that I wanted an AC30 to emulate my guitar heroes, mostly late 90s Brit-rockers. I always thought it sounded fantastic! I always loved the normal channel as a great basic sound to layer use with pedals. It seemed to have a darker sound, although still clear and tight at the low end (I also had a Fender Deluxe which I thought sounded either 'wooly' down low, or too 'glassy' up high). Definitely not the most reliable amp though, has needed a lot of repairs over the years.

[@stonemartens_music]

Thanks alot for these great videos! I'm an happy owner of an ac30 tb6/x which has been slightly modified (just few little updates). I have to say that normal channel is often underrated, I use it every time. Artists such Adrian Utley (Portishead) and Yorke, O'Brien and Greenwood (Radiohead) always use this channel to achieve their tone. Having a good eq pedal or a bright booster can help. The normal channel is a perfect platform for pedals! Thanks again, great content man!

[@plexiface7902]

Really appreciate your videos on the 90s Vox amps! Excellent.

[@svendtveskg5719]

I started playing electric in 1972. My first amp was a used AC30 TB from '65. At the time it was nothing like an icon or anything, just a used amp, that I saved up for - and Dad helpede out as well. A couple of years later it was not big enough, oh no, it had to be a Marshall 100W halfstack, oh yeah... for school parties and venues like that. I SHOULD NEVER HAVE SOLD THAT VOX! :-D

[@PsionicAudio]

When I was 20 I traded a '64 Deluxe Reverb for a JC-120. Plus cash. Because "louder." If I go to hell, that's why.

[@svendtveskg5719]

@@PsionicAudio See you there... :-D

[@Becsturf]

same. Marshall was all I saw in the early 90's. had to be a grunge kid. bought a jam 800.

[@michel333100]

Hi Lyle, I just thought that I would tell you my Vox AC30 Brian May Special Edition story. I got this amp off of a guy that had this amp in a studio that was brand new and had been used on a session in Toronto, Ontario. The guy I got the amp from didn't like it because it was too loud. When I got the amp, I started poking around on the net to get information on this amp. I found some people that were all connected in some way over Brian May's amps. One name that I came up with was a guy guy in the UK that had built a few AC30 amps for Mr. May. His name is David Petersen. The other guy from the UK as well was named Mike Ryde. Mr. Petersen and myself started talking to each other and I said that I did not like the stock sound of this remit done by Steven Grinrod that was the chief engineer on this special edition amp of Brian May that was supposedly endorsed by Mr. May. The amp in stock form was to be only the normal channel of the Vox AC30 Brian May Special Edition which David Petersen designed. It supposed to be an exact knockoff of Petersen's original schematic. Well , once the bloody Chinese got a hold of it, it was nothing like the original. Mr. Petersen sent me for free the caps and resistors and all of the parts for free. He was unbelievable. Mr. Petersen now lives in the Philippines with his wife. But for many years Mr. Petersen worked at Vox and ran his own company ShereSound company out of the UK. Well once I got these parts installed the amp somehow blew up. It was minor but I had to send it to Michael Klein in Kansas City, Missouri. This guy built a buffer for Nik at Ceriatone in Malaysia. Nik put me onto Michael Klein. He is a young bloke that is an Optometrist, but he also builds amps. Well he was kind enough to rebuild my Vox AC30 Brian May Special Edition to the exact specs of Mr. Petersen. My amp today only has one knob and that is for volume and a boost channel knob. No tone stack at all. It sounds so good that you do not need one. Mr. Greg Fryer of Australia also built these types of amps for Brian May. He is another awesome amp builder of VoxAC30 amps. Just wanted to add my little story about my Vox AC30 Brian May Special Edition amp. I love your chann else and you are obviously a guy that is well versed with these amps. My opinion is that these new amps from China are nothing like the originals other than the cosmetics of these new amps. Ceriatone from Malaysia is a different story all together. Top notch amps all the way. I own two of his amps. But this Chinese crap is unbelievable. My Vox now with the Mercury Magnetic output transformer and power transformer makes my amp now sound as good as any 60's Vox. I am quite happy with it. Like I said, I love your videos . They are incredibly interesting just like this other bloke down in Elpaso, Texas, Uncle Doug that has a KZbin channel. Very cool what you guys do. Unfortunately here in Canada, there aren't any really competent repair people.I am an old guy now and I have a lot of great amps. I play just as a hobby that I have done since I was about 10 when the Beatles came out in the 60's. Always wanted a Vox AC30 amp. But having owned this amp of mine for many years now, it's great now, but this amp was suggested retail price of $3000.00 USD. The price of this amp in 2005 was unbelievably expensive and to boot, it sounded like shite. Thanks Lyle Caldwell keep up the videos. Mike Ryde has an interesting document on the rebuild of my amp showing pictures and each step of process. All of Brian May's amps are gutted and only have the normal channel modified. Check it out. It's very interesting mate. Just as a point of interest, this amp came with the Chinese Alnico Blue speakers. I did put some old Alnico Celestion blues in the cab, but I have done a side by side comparison and I must say the Chinese blues sound every bit as good as the older Celestion UK blues that I have. That's my side by side comparison, but the Chinese Vox amps, well there is no way that I would buy one. Ceriatone all the way especially from a price standpoint. Ceriatone is state of the art guitar amps. Stacks up to anything made in the States.

[@merseybeat1963]

I don't think so..I have one of these AC30BM Amps.. I bought it new at the same time I bought one of those Limited (250 World wide) Marshall JTM45 40th Anniversary Stacks. That Brian May Amp is a perfect sounding AC30. I did have some trouble with the Treble Boost Circuit which they kindly replaced as it had a constant hum. Maybe yours was a result of faulty workmanship and why they were unloading it..as that short one year warranty is just too short a time if the Amp is rarely used. I realized my hum issue after warranty was out as well.

[@michaelnewell3823]

@@merseybeat1963 All I can tell is David Peyersen of the UK and Greg Fryer from Australia have both actually built the exact amps that were made fro Brian May to tour with. The remittance that Steven Grindrod had the the Chinese do was nothing like Petersen's schematic, but the bottom line is, that if you are happy with the amp as stock, then that is all that matters. I am just saying, after having Michael Klein rebuild my amp exactly per spec of Petersen's schematic, the amp sounds a million times better than stock. You see, the original amp has two channels actually. One is the boost channel, which is done strictly with the V1 valve being pushed to give you a treble boost that is naturally created through the wiring schematic of Petersen. The cheap bloody circuit board treble booster board in the stock amp is crap compared to Petersen's tube generated boost treble channel. It really is a thing of beauty. Just watch the video on KZbin of my amp. The video is not well recorded but the name of the video is Vox Brian May Custom- overhaul by now audio design. Michael Klein changed the sockets for the valves. So capacitors and carbon comp resistors. Vishal caps. I mean he followed Petersen's original schematic that I had sent him a copy of to his email. Absolutely an amazing American builder. This bloke is an Optometrist as well. He is very smart. He knows electronics. I am not going to say really that the stock amp doesn't sound ok, but the original schematic that this amp was supposed to be made to be was changed completely by Steven Grinrod. The point that I am trying to stress as well, the stock amp has ghost nothing when played at very high volumes. Petersen's original amp was a huge difference in tone. You hear my amp in person and you would take my amp over the stock version. I have been playing guitar since Jesus was a baby. I have played many great amps in my life. I think I know tone after all of these years. Just consider getting the conversion done and take out that awful treble boost circuit board out. You won't be sorry when you hear how that amp was meant to sound. Michael Klein works his magic.

[@merseybeat1963]

@@michaelnewell3823 Where does Mr.Klein live ? That Treble Boost Board I had trouble with which makes the Amp sound very good (which cost us in $ and stress..long story) is supposed to replicate the Booster Deacon did for Brian May for his early Vox. I wonder how similar or unsimilar the stock Treble Boost board is to what Deacon did. I would not have minded doing the upgrade if he was in driving distance. Have you tried the modern JMI Amps that were made in England..supposed to be accurate and high quality and expensive but all of a sudden they seem to no longer exist and there is a cheap imposter using that JMI logo.Do you know anything about that ? Thanks

[@michel333100]

@@merseybeat1963 no I don't know anything about that company JMI . I do remember them but like you said, they are defunct now, out of business. Mr. Michael Klein lives in Kansas City, Missouri. He runs an Optometrist business there but he also builds amps and has worked with Ceriatone amps in Malaysia with Nik Asam. What happens when you do this Petersen schematic conversion of this amp, there amp does not exhibit ghost noting at high volumes. If you read Mike Ryde's conversion papers that he puts on the net, that will explain everything about this amp that was plagued with problems from the start. This conversion gives you two volume control knobs. One is for normal and the other is for the boosted channel. There's two inputs. The conversion puts this amp in a totally different space. It sounds extremely vintage just like a 60's VoxAC30. This is not hype. Brian May actually had this amp but with the conversion done by Greg Fryer from Australia. This amp of mine is done right now and it rocks.

[@merseybeat1963]

@@michel333100 Hi ..I see the conversion papers ..very interesting but all of that work introduces a great possibility of error but if it could be done right sounds like a very good upgrade.Also sourcing all the right top quality parts and the labor required to do it sounds expensive..how much do you think it would be..plus another $200+ to ship it cross the country and back if sent to the gentleman you know. Really in 2004 I paid I think it was $2299 plus tx to buy it and another $250 to clear up the faulty Boost board which Vox Marshall were kind enough to make and supply as a courtesy this is in 2006 or 2007 or something. I probably haven't used it 4 hours since then but the Amp sounded beautiful to me but I am all for things made as they originally were. Let me ask you..this Vox AC30BM it is proper Point to Point wiring except for the Boost right ? Thanks

[@bugeyedmudafuka2]

Thanks for this. Was about to buy a 65 with no top boost. I'll hold out for a top boost so

[@middle_pickup]

I have played a lot of these Korg reissue AC30tbx amps, and they seem to be a little different sounding through the years. I love my 1993. Other ones I have played from later years were super dark. Did they change them much as the years went along? Between myself, and all my church friends we must have half a dozen of these amps. They all sound kinda different. The closest to mine is my friends number one amp, also a 1993. Enjoying the channel! I love learning about this stuff. You're tempting me with the vibrato channel pot idea! 🤔 💡

[@PsionicAudio]

Thanks! AFAIK the circuit stayed the same through the years. 2-3 different board revisions but thosev were slight layout changes. Maybe they changed iron but I don't think so. AC30s can be tricky to compare to each other, as very slight changes the in TB settings can yield radical differences, and the pot tolerances are fairly wide, so two different amps' treble pots set to the same o'clock setting may not in fact be set the same.

[@middle_pickup]

@@PsionicAudio I've seen different looking capacitors in them. Orange drop looking ones, blue ones etc. I wondered how different those parts make it.

[@PsionicAudio]

Not at all.

[@violentomar]

Also keep in mind that the tubes used and tube combinations you choose to use in these amps play a big part in shaping the sound. Beatles aside, I think that blank slate versatility is what has helped this amp to endure for so long (especially the JMI and Korg Marshall TB/TBX reissues).

[@richclayton5785]

Hendrix was very jazzy, so that was a good lick for a jazz demo.

[@chojinkid]

Thank you for these videos, Vox community really needed this, one question, was the normal channel of the original JMIs as dark as the one on the TB/TBX reissue?

[@PsionicAudio]

Yes, really dark and boomy. But the originals didn't hum like the stock TBX. Notice Rory Gallagher and Brian May never turned their Rangemaster Treble Boosters off.

[@chojinkid]

@@PsionicAudio yes, with the treble booster always on the normal channel gets even better than the TB channel alone those artists always said.

[@Slammintone]

What output tube brand are you using here, and which version of JJ 12AX7 do you use? Thanks!

[@steveymoon]

Thank you so much for this. What are the mods you made to the normal channel? I'm in the UK, otherwise I'd send you my amp.

[@ocduff]

Another option, if noise bothers you on the TBX series, “delete” the oft-unused and noisy Vib/Trem channel by pulling the 3 pre-amp tubes on the back right side of amp. Amp will be noise free and work normally. Your valuable UK Drake made trans will run cooler, you’ll have 3 pre-amp tubes in your stash, and your now collectible amp will remain so.

[@PsionicAudio]

No, that's not how this works. The Vibrato channel tubes being pulled do not magically erase ground loops, bad heater dress, and noisy PTs.

[@ocduff]

No more than adding oil to an engine leaking some would solve an oil leak, but it does help the overall issue. And in this instance (and it’s the left three pre’s, I misspoke), a whole channel and its associated noises are cut out of being amplified. Between that - and ideologies aside - tweaking heater wires, setting opposing channel to noise free setting, the minor issue can be - perhaps not solved - but certainly mitigated.

[@5756strat]

Hi, the crossover channelling is a little out of screen shot - are you crossing the the bottom inputs of both channels and using the top inputs (either normal or brilliant) for the guitar ?

[@joshuakessler4634]

Thoughts on Greenbacks vs Alnico's?

[@FOXDADDYSUPREME1]

Hey, thanks for the video. I decided to pull the trigger on an ac15tbx after watching this. It needs new tubes though, any suggestions? Thanks!

[@carlosalves4444]

You know I'm getting to the point where, I'm seriously considering ditching the tube amp and the constant crap of maintaining these things and can't play them at any decent level and going to plugging as when doing a a/ b/ C test actually prefering the sound of the plug ins without pissing my neighbours off and have options that one amp just can't do.

[@jaycee30865]

Chinese blues 2010 absolutely equal to current and 2003 blues. DOD 270 a/b pedal proves it. Pulsonic era probably a different animal.

[@cobowe]

I have 60s,70,s and New Chinese blues. The new Need to be worn in to sound good... But they don’t touch my 60s Silver dogs

[@jaycee30865]

@@cobowe paper formers is why

[@ThemanfromZambodia]

That tremelo sounds nothing like the 2003 handwired ac30 model I play through.

[@Slammintone]

Umm, your Vib/Trem switch is backwards or something. When you show it switched to Vib it’s choppy like a trem and when switched to Trem it warbles like a Vib.

[@PsionicAudio]

That was Korg, not me. ;)

[@Slammintone]

@@PsionicAudio it sounds good! I wish Vox would have kept the Trem circuitry the same for the AC30C2. It’s not as intense as it is on the TB/TBX.