Vox AC30 Custom Classic : Common Issues & Tech Tips

[@nigelduckworth4419]

I have a marshall built 1997 AC30 (not CC) on which the top boost channel was fading out to nothing after a few minutes playing. The normal and tremolo channels were ok. I paid £180 sterling to an amp tech to fix it and it did work for a week or two and then started to fade out again. He had replaced the power tubes and also some condensers. I got hold of the wiring diagram and studied it, even though I have no electrical experience. I decided that the input valve splitter might be at fault and replaced it. Result: no more trouble for a few years. I think that this bit of common sense as I call it, might help others who have experienced the same problem if the problem is not solved by your excellent video.

[@outofcontrol-au2tribute383]

Grateful for this video - I have a 2005 CC2 (only mod is a Weber Copper Cap SS rectifier) that started acting strangely a few months ago - a dramatic drop in volume, with a thin sound along with some hum. No scratchy pots or switches, and all tubes confirmed to be working properly. Changing the input volume on the normal channel would occasionally make it "wake up" (startling everyone with a sudden increase in volume). Then it would function normally until the end of the session but same thing happened again next time I powered it up. After watching your video, I sprayed contact cleaner into the effects loop switches and cleaned the input jacks. PROBLEM RESOLVED.

[@milespunter9791]

Really helpful. My amp used to fizzle out when hot, changed the valves to cracking Russian units, brilliant high treble sound but it didn’t help. Was thinking it would have to go in for repair but seems it was a dry loop switch. I flicked back and forth a few times and problem solved. Happy as a pig in ****. Cheers

[@miristebivka2694]

Lyle, just discovered your YT today, though as a CC2 owner I have been aware of your name and mods for a long time. Glad you're here. I had the same 'fizzle out' problem, I have taken the amp apart a bunch of times to see what's up. Finally today I discovered the culprit was the loop bypass switch. Just flicked it on and off and the problem disappeared. So probably a bad switch, though have never used the loop. I've seen the same issue come up online when searching for a solution, but no answer until accidentally today. Thanks for sharing what you know, Lyle.

[@HF1600ie]

Mine also muted himself when i was using the loop until I flicked the switch a few times. Then I used de-oxit spray in there a few times and seems to be fine since.

[@IndianaDoug]

Just stumbled upon the channel. Very impressed, thanks for sharing your work. I am now subscribed and look forward to future videos.

[@PsionicAudio]

Thanks!

[@JPDESS]

Hi did the effect loop on this thing, and prefer the original with .22 and 10uf. I think its better as it is than with the 2.2uf. One thing youre right is the input jack, if they doesnt touch the chasis it can also create oscillation on top boost channel. My advice is to bring them back after cleaner, but gently not to break them. Otherwise this thing sound great and doesnt not need any mod if you like classic rock tones. I thing mr grindrod did a great job on the custom classic. I prefer them over the other vox ac 30. Thanks for the video!

[@PsionicAudio]

Um, you like losing the lowest octave of the guitar when the loop is on?

[@JPDESS]

In this circuit its better not to add to much bass before the output section when overdriving the first stages

[@PsionicAudio]

It doesn't add any bass. It's a simple highpass filter. But if you are playing high gain, you very well might like the effect. It doesn't hurt anything, and if you like it, you aren't wrong for that. But it was a factory mistake that you happen to like. Given where the client has his Bass knob set, he doesn't seem to. ;)

[@cjmutschler]

@@PsionicAudio Yeah was gonna say... there are times you want to pull in the bottom end... but it's nice to have the option and it's not intuitively "I am using the effects loop... therefore I want to boost the mids/highs".

[@Saturnine10]

Can you use a radial cap for the fx loop fix or does it need to be a box type? What orientation? Amazing channel for sure, thank you for all your awesome work!!

[@PsionicAudio]

Thanks! It's hard to find a film box cap 2.2uf or larger that will fit the available space, so I use an electrolytic. Negative facing the Send Jack.

[@fordsrestorations970]

Thanks I'm trying to learn everything I can about Vox amps.

[@OZKÄRSTALIN]

Hello!! I just bought a Vox AC30 TBR 1985 - 25th anniversary. When the seller sent me videos the amp works fine but once the amp was delivered when I open the box the first thing happened was that a little fuse came out from the leathet cover, I plugged the amp and it turn ON but it doesn't sound at all. I checked the fuses in the back panel and they were there, now watching this video I could see that are 2 internal fuses. The thing is that my model the inside is different than this one on the video, I am not sure at all if the fuse is the problem yet, the claim with the delivery company started and I'm afraid that touch it and make a mistake, I don't have really experience open amps and fix them. Could you give me your opinion of what I am sharing with you? Do you think my amp model has internal fuses like you're showing in your video? Thank you so much.

[@nickven156]

Thank you for this video! I have a ac30cch head, but there are soms problems. I cant get in in overdrive, how high i set volume. It stays clean. Also tremolo and reverb doesnt work. When i turn reverb on then i hear a loud hum. The hum has a reverb sound. It is pulsing. Hum goes on and off like reverb. Reverb tank is new and leads are good. Do you ever heard of this problem?

[@jaycee30865]

Getting the fx board out- can it come out without removing other boards or is it a mess? Great videos thanks.

[@Reverend_Taco]

Boy I wish mine was one of these later ones, ‘cause the four speaker wires clipped straight to the circuit board really sucks!

[@ronnieholm8838]

Love your videos. If you should pick between a Vox ac30h2 50th anniversary and a Vox ac 30 from 1970. What would you say would be the best pick? Are the transformers in the ac30h2 50th anniversary just as bad as the other transformers? And need to be changed? Bedt regards Ronnie Holm

[@jimcastillo8950]

Hello, question, my friend has a Vox AC30 and while playing his sound went weak. He looked at the tubes and they were not glowing. He has sound but not like it was so would this be the heater circuit? and can an amp still work without the 6.4 volts? thank you......

[@cjmutschler]

Mine has gotten really buzzy since I changed speakers and put it on an amp stand that tilts the amp back about 15 degrees. Sounds like maybe I need to check those input jacks.

[@tilersun]

My amp is fine for about a half hour before the volume begins to randomly drop out for a few seconds. I replaced all 7 tubes (the rectifier is removed for a solid state). Gonna try cleaning it but something says it's a different problem. Any ideas??

[@chrisdee5032]

I have a Custom Classic and love it having carried out many of your mods to it! I was thinking of changing the filter caps to F&T caps, are they a good brand for these amps?

[@PsionicAudio]

It's tricky. F&Ts are great, but they are physically larger than the original axial 22ufs, and there are relatively few axial electrolytics being made today. Four F&Ts will not fit, so you have to decide whether you will just do 22uf + 22uf or 47uf (single cap) and 22uf. So the stock 22/44 switch has to be abandoned. Unless you added terminal strips inside the chassis which would take radials.

[@brunosucheck1191]

Thanks for the video just got a cc2 with blue alnicos, and I'm in love with it. What do you think about the stand by switch on this amp? I've heard that using it can blow the rectfire tube. Ps: poor english here greetings from Brazil

[@PsionicAudio]

The standby isn't needed in any amp with a tube rectifier, and on the CC it kills rectifier tubes. Just use the power switch, leave standby in the playing position at all times.

[@brunosucheck1191]

@@PsionicAudio thank you

[@pedroromero1870]

Hello. Could you tell me what preamp tubes do. V1, V2 and V3? Thanks

[@jonbuckner4467]

I opened up my AC30CCH, circa 2007/2008 I can’t see the 2 fuses you point out on the circuit board, do not seem to be there ….

[@dangitdan9938]

Pretty sure I’m getting an AC30 in the next couple weeks here and one of these is for sale local for not too bad money but I’m wondering if this is a good buy or should I get a new one or a different model? Any help y’all?

[@patinthechat6452]

You mentioned the metal rings on the input jack having poor contact with the ground. Could I use di-electric grease on those rings to help prevent it from happening again?

[@PsionicAudio]

No. Just have the metal surfaces clean and tight against each other.

[@cjmutschler]

Speaking from experience 😂... you can buy a power screwdriver that allows you to "angle" between the tip and the handle. Mine does not go to full 90 degrees... but it still prevents 75 percent of the cussing. 😂

[@GShockWatchFan.]

Does custom classic share same common issues as C2 you mentioned in other videos? I.e the arching and potentially burned board

[@PsionicAudio]

No, It has other issues. ;) Both amps’ issues are pretty minor though.

[@gearoftones8585]

See on the CC2, can you make the brilliant setting on the normal channel a little less bright by changing the capacitor on that switch? If so, what value cap would you suggest? I find the normal channel just a tad too dark and with the brilliant switch on its just a tad too bright sometimes

[@PsionicAudio]

You can. But first find the 330k resistor in series before the Normal volume. Jumper that. You'll get more gain and less brightness. Easier to do without disassembling the amp.

[@Pablo-nc6qu]

I found changing R6, R7 to 220k solved the brightness issues on my cc1. Added gain too, made it awesome.

[@raulgrangeiro]

Friend, does a Vox AC15 need to have the BIAS adjusted when changed the tubes?

[@PsionicAudio]

No

[@raulgrangeiro]

@@PsionicAudio Thanks for answering me this question. Don't adjusting the BIAS doesn't cause sound issues on the amp when tubes are changed?

[@papahjoshscene4234]

I have a vox vt30, but now there is a problem. if I play for 30 minutes, the sound suddenly decreases and hoarse. what's the problem?? Please help me. Thank you

[@cgavin1]

Mine fizzled out for many years before I figured out that the CON5 ribbon had come loose and re-hot glued it.

[@chrisdee5032]

Lyle, is it possible to bypass the master volume on these amps. Maybe it's pointless and will make no difference but I always run mine with the MV fully open.

[@PsionicAudio]

Yes, on the top board there are two traces from the ribbon cable to the master volume pot. Cut either of the two traces. No more MV.

[@chrisdee5032]

@@PsionicAudio Thanks for the info Lyle, I'll give that a go!

[@chrisdee5032]

Lyle sorry to revisit this question but I've only just got the time to get my amp taken apart again. Will removing the master volume pot completely have the same effect as cutting one of the traces or does something need to remain connected in the circuit? Thanks again!

[@PsionicAudio]

@@chrisdee5032 no difference. Cutting the trace is easier than removing the pot, and if you remove the pot there's a hole in the chassis. Cutting the trace is also more easily reversible if it's needed later.

[@chrisdee5032]

@@PsionicAudio Thanks again Lyle. I removed the MV from the circuit and I'm getting a little bit more output from the amp now I think. Thanks again for your help!

[@MyMotherTheCar]

You don't want to go too HAM with the power screwdriver. The screws are made of incredibly soft metal and strip out very easily.

[@PsionicAudio]

Amen. I have the power driver set to lowest torque for them, and I start with the barest touch on the button. Lots of experience, and I've replaced many CC screws that others butchered. I just sped up that part of the video to keep the overall length short.

[@voxpathfinder15r]

Why was this series panned so much? Seems like on paper it should be much better than the following custom series

[@PsionicAudio]

Three reasons. 1) They had a factory error causing the loop to lose low end. 2) First amps made to new EU safety specs, so they couldn't use the old cotton grill cloth, and the substitute looked more plastic (since corrected). Also some weird looking purple/pink control panels at times. 3) First Voxes made in Asia, and American buyers tend to be a little bit racist about such things. They love to hate on Asian manufacturers, usually using an iPhone or Android to do so. It's a funny world.

[@voxpathfinder15r]

@@PsionicAudio the classic custom series have real birch combo boxes, right? And hand wired power tube sockets? Seems to me I would pick that one and follow your mods to bring it up to snuff. Agree, disagree?

[@w0lfcrY]

Hello from Greece, i have a problem with the standby , its not working, i just change tubes and fuses but it still not working 😕

[@PsionicAudio]

First, don’t use standby on this amp. It isn’t needed and it kills rectifier tubes. Second, the CC has fuses inside the amp on the power section board. Not just the two externally accessed fuses.

[@w0lfcrY]

@@PsionicAudio thanks for your reply , i watch your video and checked the 2 fuses on board. Its possibly to play without the standby? I don't have a signal, can i send you a video or to upload in my Chanel and watch it to tell me your opinion ? Thank you 🙏

[@PsionicAudio]

Sorry, was thinking Custom Classic. On the Custom you do need to use the standby switch. If all fuses are good and you have known good tubes and you still have no sound, make sure the speaker is good. Use the external out jack to run into a different cab if you can.