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OT: School me on the AC30 Bright cap mod AC30 History


Josh33

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so... ive heard some ac30s letely and they have all sounded spectacular. the problem is every time i play an ac30 i absolutely hate it. i dont really know much about vox amps but i know i like my ac4 and stuff..i really like the sound of the heritage stuff but that is alot of monies.

 

so whats the deal?

do the newer ac30s just suck? (arnt they chinese or some asian country made now)

 

do those bright cap mods really help?

 

any history on the ac30?

 

sorry for all the random qustions but its the one amp ive never really known much about. i think the reason ive never liked them is because ive usually only played the ones at GC that have been beat to hell and they give me a {censored}ty ass guitar with no set up or anything to try it out with... but yeah... lets discuss this {censored}.

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The sound quality of the new AC30cc's is quite variable - Because I've got one, I usually ask to play through one when I try gear out in guitar shops, and I've heard some absolutely disgusting amps. Usually the bad ones have wharfdale speakers that aren't broken in.

 

Most of the horror stories relating to unreliable amps come from the first few years of their production in the far east. They are generally much better now, and the ones that sound good are generally considered to be very close to the original '60s versions - go over to the vox forum on plexi palace, there are a few people there who own both vintage and modern AC30s who think the new ones are as good.

 

I think the amp sounds much, much better with Alnico speakers like the Celestion Blue, Webber Blue Dog etc. The wharfdale speakers generally sound too grungy, fizzy, plasticy and stiff. I don't think they do the amp any favours at all. Also, the valves that come in the amp aren't awful, but upgrading them to NOS or even better new valves makes a big difference.

 

The bright cap mod makes a difference, I performed it to my amp about 6 months ago. Basically, the treble cap "bleeds" high freqencies past the top boost volume pot when it's turned down. So if you turn the volume up to max, it's not doing anything. But if you've got it turned down and you're using boost/distortion pedals, an unnatural amount of treble gets through the input stage and makes the amp sound harsh in a way that's nigh on impossible to dial out. By cutting this cap the tone doesn't get too bright when you're boosting the amp with pedals, and sounds a more musical. You can still get "bright" sounds using the EQ, it just means as you turn the volume down the amp doesn't get relatively brighter.

 

Alternatives to this mod are to replace the treble cap with a lower value, which some people recommend if you mainly use a humbucker equipped guitar. I believe the '60s AC30s used a bright cap that is half the value of the one on the CC series.

 

So I recon all in all the new CC series can sound as good as the old AC30s, as long as you don't pick one of the bad ones, and invest in decent speakers, valves, and time to learn how to dial in the tones you want as the interactive EQ takes a little getting used to. I've not bothered talking about upgrading the filter caps, transformers etc because that gets pretty pricy and the resulting "improvement" is really a matter of taste, and I don't think it's necessary to get good tones.

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There's two problems with the CC amps. One is the bright cap making the amps pretty bright and, in the case of the AC15CC, close to unplayable with how I like my gear (and no, it's not a case of 'just turn the treble down'). The other is that the Chinese-made Celestion Blue speakers (Chinese made are labelled Vox on the bell cover, the UK ones are labelled Celestion) are a lot brighter and harsher than the UK ones. So bright cap + bright Blue speakers = a shitload of brightness in one amp especially when you dump pedals into the equation.

 

I've said many times on this forum that the AC15CC1X is the shittiest amp I've ever owned. The reverb is crap, the trem isn't that special, the quality of the cabinet isn't high, the stock amp sounds like arse, and the Chinese Blues are shit. The AC30CC on the other hand is something I like. It pisses all over the AC15CC. If I were in the market for an AC30, and one day I will be, I'd go like this:

 

-Buy an AC30CC head unit. Ignore the combo and save your back :D

 

-Carry out the bright cap mod.

 

-Source a separate cabinet. In the US, somewhere like Avatar, Mojotone, Lopoline, whoever you want. The Vox 2x12" cabs with Chinese Blues are pretty bloody horrible.

 

-Source your own speakers. Weber Blue Dog or Silver Bell, UK made Celestion Blue or Gold, Eminence Red Fang, Greenback and clones... whatever you fancy really.

 

-See how you like the amp now. Bear in mind the speakers will need time to break in.

 

-If the amp sounds too bright still, consider dumping out the stock valves and switching to JJ tubes. These are a little darker in tone to the usual Sovtek/EHX valves Vox use. You could investigate using a 5Y3 instead of a GZ34 rectifier.

 

-If you're still not happy, then consider things like caps and transformers.

 

A few simple changes can make an AC30CC sound really good.

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Yup, good point about the Chinese blues HeartfeltDawn, there's a clip somewhere on youtube demonstrating the difference between China and UK made blues.

 

I think that one of the things that makes vintage AC30s sound so sweet is simply that some of them have speakers that are 40 years old. I think it'd be hard to get anything but a warm tone from them! Of course, they might blow out at any moment - but that's the price you pay!

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thanks for all the help guys... some really good useful information in here. thanks a ton. im not really in the market to buy an AC30 right now but will be soon and i was just really curious about all of this stuff. but i am definitely thinking about picking one up down to line and this has helped and will help me a lot. this explains why the ones ive played have sounded so crappy. they have had the same ac30 at our guitar center for a few years. so... people beating on it + low volumes + crappy production (crappy speakers, no tube replacement, no bright cap mod, not nesecerrily broken in) = crappy experience. ill have to try and find another one to try and hopefully hear the possibilities with some upgrades. i liked the idea of getting a head too... that might not be a bad route to go.

but anyways... thanks again for all the information guys! good stuff! :thu:

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What you are saying about Chinese blues compared to the UK ones is kinda interesting. I read on the vox forum that they are basically identical. Some players even preferred the Chinese ones.

 

 

Of course some people will prefer the Chinese one. It's a purely subjective issue. Some like UK Blues, some like Chinese Blues, same as any speaker by any maker.

 

There is a sound difference between the UK Blues and the Chinese Blues. I've had 2 speakers of each type and it's audible even to a cloth-eared peasant like myself. The Chinese speakers sound harsher to me. I don't like them. Other people do. Voxman's post in this link sums it up perfectly:

 

 

Hi Rojo - Just to clarify, there has been very detailed discussion on this topic from which I think you'll find that care has been taken to expain that there are some differences in the physical materials used, specifically the cone material, which is a matter of fact. That is not to suggest that one speaker is inherrently better or worse than the other, merely that there are some tonal differences. Each person will have their own personal preference as of course tone is very much a personal objective rather than subjective view. There are those that cannot discern any noticeable tonal differences whilst others are more sensitive to the tonal variation.


It is of of course of no consequence whatsover, as you rightly say, as to where the speakers are made - the discussions have merely focussed on the perceived tonal differences and that the images on the Vox product section showed pictures of the UK variant when in fact it was the Chinese variant that is supplied with Vox amps. To avoid any further possible confusion this has now been updated by Vox and the pictures now show the Chinese variant with the 'vox' label'.


The merit of the Chinese variant is, from Vox' perspective, better consistency of build quality.


For my own curiosity, I have compared an AC30 with the UK variant and one with the Chinese variant. Whilst I could not discern any major difference when clean - possibly the UK variant seemed slightly 'sweeter' & brighter - to my ears, there was a bigger tonal difference when the amp was cranked for distortion & when a treble booster was added (I used a Vox cooltron pedal). The Chinese variant seemed to break up a little earlier and the distortion tone was a little different - pretty much as per Pemich's you-tube clip. Both sounded very good & sounded 'Vox', but the characteristics were definitely a little different. There are a number of comparative sound clips posted, which further evidence the difference, & as i said, it's down to each individual as to which they prefer.

 

 

http://www.voxamps.com/forum/topic.php?id=676&page=2

 

Neither speaker is 'better'. It's all down to what you prefer.

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