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Can I get drippy reverb w/AC30 by switching tank?
Old 4th August 2020
  #1
Here for the gear
 

Can I get drippy reverb w/AC30 by switching tank?

I recently got a Vox AC30 cc2, and the reverb tanks are notoriously crappy and frequently replaced. Before this amp, I was pretty accustomed to the spring reverb coming from a Fender Blues Jr, and tbh I miss it a lot.

Since then I've learned that I really like drippy, springy reverb, and that it's difficult to emulate without buying an expensive AF pedal. However, I like my new Vox and I'm not going back to the Blues jr.

This may sound like a stupid question, but I've looked a bit and can't find any internet threads about anyone who has done this - is it possible on my vox to switch the reverb tank to one that will sound more like that Fender spring that I'm used to? Or maybe even more drippier than that?

Thank you for your help!!!!!!!!!!!!
Old 4th August 2020
  #2

So, you like the bad sounding reverb better than the smooth Vox response....

There's more than just the tank. You might do well to get a "spring reverb" pedal and put it in the effects loop. I like the Boss FRV1, but there are others out there that are very fenderesque...




-tINY

Old 4th August 2020
  #3
Deleted dc388e1
Guest
Quote:
Originally Posted by joythirstpop View Post
I recently got a Vox AC30 cc2, and the reverb tanks are notoriously crappy and frequently replaced. Before this amp, I was pretty accustomed to the spring reverb coming from a Fender Blues Jr, and tbh I miss it a lot.

Since then I've learned that I really like drippy, springy reverb, and that it's difficult to emulate without buying an expensive AF pedal. However, I like my new Vox and I'm not going back to the Blues jr.

This may sound like a stupid question, but I've looked a bit and can't find any internet threads about anyone who has done this - is it possible on my vox to switch the reverb tank to one that will sound more like that Fender spring that I'm used to? Or maybe even more drippier than that?

Thank you for your help!!!!!!!!!!!!
Hi,

Is the CC2 the older Vox, with the single input, or the more recent version with the Normal/Top Boost inputs?

Some years ago I had an AC15 CC2 (I think - it was the older version with the single input). I had similar issues with the less than excellent reverb tank, so I switched it for the tank from a Laney VC30.

From memory, the reverb unit from the VC30 was a 12" tank, whilst the tank from the AC15 was 8" or 10". When fitted to the Vox, the 12" tank produced a much lusher reverb than it's predecessor.

One thing to consider - different reverb tanks have different input and output impedences. I played my AC15 with the Laney tank for years without any issues, but I may have been lucky.
I don't think mismatching impedences will harm your amp (although best ask a qualified repair person to be on the safe side), but a mismatch may cause crappy sound.
Valve reverb tanks typically operate on tens of ohms, solid state tanks hundreds or even thousands. The tank in your Vox will be driven by an op-amp, and so will expect a few hundred ohms at least.

There are also myriad grounding schemes, although these can often be jumpered to suit. Here's a guide to what the code on a standard Accutronics tank is telling us:

https://www.amprepairparts.com/reverb_numbering.htm

If you have the code for your unit, you should be able to search out a matching tank with longer springs.



Edit: I took 'drippier' to mean smoother/lusher. It occurs to me now it may mean splashier/nastier. That being so, the advice still applies, just look for a shorter tank instead!

Last edited by Deleted dc388e1; 5th August 2020 at 10:17 AM.. Reason: Clarification.
Old 5th August 2020
  #4
Here for the gear
 

Quote:
Originally Posted by kingofspain View Post
Hi,

Is the CC2 the older Vox, with the single input, or the more recent version with the Normal/Top Boost inputs?

...

If you have the code for your unit, you should be able to search out a matching tank with longer springs.


the CC2 I have has the separate normal and top boost inputs

anyways, this is exactly the answer I was looking for. Thank you!

Quote:
Originally Posted by tINY View Post



There's more than just the tank. You might do well to get a "spring reverb" pedal and put it in the effects loop. I like the Boss FRV1, but there are others out there that are very fenderesque...


-tINY

I love the sound of the FRV1, and would jump on it in a second if I had the money. But, replacing the tank is $~20-30 compared to hundreds, so that's more realistic for me right now.

Thanks for your answers!
Old 6th August 2020
  #5
Lives for gear
Quote:
Originally Posted by tINY View Post

So, you like the bad sounding reverb better than the smooth Vox response....

There's more than just the tank. You might do well to get a "spring reverb" pedal and put it in the effects loop. I like the Boss FRV1, but there are others out there that are very fenderesque...




-tINY

Yeah, kind of surprised as few people think of the Blues Jr. with its digital reverb circuit and tiny tank as a good Fender reverb sound... but to each their own.

Given that the CC2s have (or had) a lot of reliability issues, you may want to ensure everything is correct on the amp before trying to swap reverb pans.
Old 6th August 2020
  #6
Deleted dc388e1
Guest
Quote:
Originally Posted by nedorama View Post
Yeah, kind of surprised as few people think of the Blues Jr. with its digital reverb circuit and tiny tank as a good Fender reverb sound... but to each their own.
Unless I'm mistaken, the Blues Juniors reverb circuit is solid state, not digital.

https://elektrotanya.com/PREVIEWS/63..._sch.pdf_1.png

Like a lot of modern amps (the Vox AC30 CC2 included), it's driven by op-amps rather than valves, but it's still driving a good old fashioned spring tank.

Using op-amps is more effficient than valves, which waste a lot of energy generating the currents required to feed a spring tank, plus you loose the need for an extra transformer.
Whether one or the other is tonally superior is in the ear of the beholder - I'm ok with either.

I'll be happy to be corrected on this, but I think from an engineering point of view, op-amp is superior. I'd wager the reason a lot of high end amps still use valves to drive the reverb is less about tonal superiority, more to do with the mains transformer needing extra taps for to feed the op-amps the +/-15V.

Old 6th August 2020
  #7
js1
Lives for gear
 

I stuck an Accutronics tank in my AC15CC1, and it's better, but the results were not as good as I hoped. Still sounded cold.

And from an engineering point of view (I'm an old EE), op amps are not necessarily superior. Depends on the application.
What they are is versatile and cheap. Both in parts cost and manufacturing (automated assembly).

A tube reverb circuit is much more expensive, the tube alone costing more than entire op amp reverb circuit. There's a reverb driver transformer, so you don't save on iron.

Last edited by js1; 6th August 2020 at 05:52 AM..
Old 6th August 2020
  #8
Lives for gear
Quote:
Originally Posted by Deleted dc388e1 View Post
Unless I'm mistaken, the Blues Juniors reverb circuit is solid state, not digital.
You are correct; I was using digital to mean solid state, not tube-driven.

https://elektrotanya.com/PREVIEWS/63..._sch.pdf_1.png

Quote:
Like a lot of modern amps (the Vox AC30 CC2 included), it's driven by op-amps rather than valves, but it's still driving a good old fashioned spring tank.

Using op-amps is more effficient than valves, which waste a lot of energy generating the currents required to feed a spring tank, plus you loose the need for an extra transformer.
Whether one or the other is tonally superior is in the ear of the beholder - I'm ok with either.

I'll be happy to be corrected on this, but I think from an engineering point of view, op-amp is superior. I'd wager the reason a lot of high end amps still use valves to drive the reverb is less about tonal superiority, more to do with the mains transformer needing extra taps for to feed the op-amps the +/-15V.

Lots of modern inexpensive amps use opamps to drive their reverb, where as you move up in price and quality, they're tube driven. The Blues Jr. and CC2 were both built to a price point, and for that price point most users are fine with the solid state reverb drivers.

As for your thinking on tonal superiority, I doubt it; if opamps sounded better boutique amp makers, especially those already using PCB construction, would be shifting to that - but from what I can see, they're not. But would be interested to see any quality amps that use op amps for reverb driver/recovery over tubes.
Old 6th August 2020
  #9
Quote:
Originally Posted by kingofspain View Post
Unless I'm mistaken, the Blues Juniors reverb circuit is solid state, not digital.

https://elektrotanya.com/PREVIEWS/63..._sch.pdf_1.png

Like a lot of modern amps (the Vox AC30 CC2 included), it's driven by op-amps rather than valves, but it's still driving a good old fashioned spring tank.

Using op-amps ...


I have a Vaporizer (sounds good with decent speakers). It has an op-amp tank driver (no transformer) that gets pretty drippy. There is a current feedback in the circuit that compensates for drive-coil inductance - so it drives the tank like a triode and transformer would.

Not sure how the Vox circuit compensates. I have one and the reverb is fine for me, but it don't surf..... The Vox doesn't have the right bottom end for that anyway.



-tINY

Old 6th August 2020
  #10
Here for the gear
 

Quote:
Originally Posted by tINY View Post



Not sure how the Vox circuit compensates. I have one and the reverb is fine for me, but it don't surf..... The Vox doesn't have the right bottom end for that anyway.


-tINY

I have noticed the lack of bottom end- recently got an EQ pedal, stuck it through the FX loop... can get a surprisingly gratifying amount of more different sounds out of it now!
Old 6th August 2020
  #11
Deleted dc388e1
Guest
Quote:
Originally Posted by nedorama View Post
You are correct; I was using digital to mean solid state, not tube-driven.
Fair enough, but you probably wouldn't say football when you meant baseball

Quote:
Originally Posted by nedorama View Post
As for your thinking on tonal superiority, I doubt it; if opamps sounded better boutique amp makers, especially those already using PCB construction, would be shifting to that - but from what I can see, they're not. But would be interested to see any quality amps that use op amps for reverb driver/recovery over tubes.
If you re-read my post, you'll see I didn't claim either method was tonally superior. I said I thought the op-amp was technically better at doing the job, but I'm not an electronics engineer and wasn't making a definitive statement.
How good or bad the reverb sounds - be it valve or op-amp driven - will have more to do with how well the circuit is designed and integrated into the amp, than the technology used. There have been plenty of lacklustre valve driven reverb circuits over the years - for example, Vox used a single ECC83 to drive the reverb in the AC30 for a while, producing a predictably weak sound.

There are some 'boutique' amps which use SS technology to drive the reverb. Hamstead is the first which springs (no pun intended) to mind:

https://www.soundonsound.com/reviews...ks-artist-20rt

I'm pretty sure I've come across a few others over the years.

The elephant in the room here is that - rightly or wrongly - a lot of us slavishly think valves = better. Amp makers are wise to this, and so valve reverb becomes as much a status symbol as a means of driving the tank.
Advertising a 'highly efficient op-amp reverb driver' wouldn't sell many amps, perhaps if we were less biased (pun intended) towards our vintage tech, it would...


Last edited by Deleted dc388e1; 6th August 2020 at 04:30 PM.. Reason: syntax
Old 6th August 2020
  #12
Deleted dc388e1
Guest
Quote:
Originally Posted by tINY View Post


I have a Vaporizer (sounds good with decent speakers). It has an op-amp tank driver (no transformer) that gets pretty drippy. There is a current feedback in the circuit that compensates for drive-coil inductance - so it drives the tank like a triode and transformer would.

Not sure how the Vox circuit compensates. I have one and the reverb is fine for me, but it don't surf..... The Vox doesn't have the right bottom end for that anyway.



-tINY

I had a Vaporizer for a while, I remember the reverb being a little screwy, but in a good way. You could turn the master all the way down and just play the reverb circuit.
Not sure why we parted ways now, as I liked it a lot. Too loud, maybe...

Old 7th August 2020
  #13
Here for the gear
 

so just to clarify... besides something potentially being wrong with the amp as someone mentioned (more likely it's the tank since these particular ones fail all the time) - is there anything that I am very likely to run into that could potentially prevent a different tank from sounding as drippy in a vox ac30 as it would in a fender? I can't imagine how, but, thought it would be a good idea to ask before spending the $
Old 7th August 2020
  #14
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Cirrus's Avatar
 

Yep, there might be something that thwarts you - the power section & speakers of an AC30 are different to most fenders.

The latter tend to have more headroom, and a cleaner, flatter sound before the onset of power saturation which gives the reverb a chance to be clear, clean and deep. Likewise the speakers are often higher powered relative to the amps' output, which means they can reproduce the dry and reverb sounds better.

Whereas an AC30, with 4x el84s, no negative feedback, and speakers that are more closely matched in power rating to the amp output, is a different story - the power section breakup starts earlier and is more gradual, so the headroom even at cleaner settings isn't necessarily there to stop the dry and reverb sounds from mushing together, and especially in the lows give the reverb the space it needs to sound rich.

I had a CC series for a few years, they're good amps. A few reliability foibles, but I'd rather have one of those than the C series that replaced it.
Old 7th August 2020
  #15
Here for the gear
 

very interesting information, thank you. I'm very uninitiated into that type of info. I like the sound of the AC30 but can't see myself buying another fender just to have that reverb sound that I like out of the fenders - I'm pretty dirt poor (I could only buy the CC2 from the last stimulus check ) and live in a tiny place, no space for another amp. Guess I will just have to see how good I can get it with what I have and make do, f**k, lol.

In another thread about the CC2 someone had mentioned something about plugging pedals etc directly into the fx return loop in the back and bypassing some of what gives the vox its particular tone - I've played with the thought of using a preamp pedal that emulates a fender and seeing what kind of variety of tone I can get out of the amp. Not sure how much more play that'd give me though, I still don't understand much of this stuff.
Old 7th August 2020
  #16
Gear Addict
 

Forgive me if I’m stating the obvious but „drippy“ reverb is not the kind of effect you get with amp spring reverb.
You need an external reverb tank going in before the preamp, like a pedal.
Old 7th August 2020
  #17
Quote:
Originally Posted by plastic_ View Post
Forgive me if I’m stating the obvious but „drippy“ reverb is not the kind of effect you get with amp spring reverb.
You need an external reverb tank going in before the preamp, like a pedal.

I haven't found that to be true. A stand-alone unit into a pretty clean amp is one way to get it. But, as long as the pre-amp isn't compressing the signal too much, you can get a drippy reverb out of most of the older Fender amps - and most of the newer ones.

Heck, I have a Vox that gets pretty drippy - and it has a digital reverb. It's not an AC amp, it's an NT.





-tINY

Old 8th August 2020
  #18
Quote:
Originally Posted by nedorama View Post
Yeah, kind of surprised as few people think of the Blues Jr. with its digital reverb circuit and tiny tank as a good Fender reverb sound... but to each their own.

Given that the CC2s have (or had) a lot of reliability issues, you may want to ensure everything is correct on the amp before trying to swap reverb pans.
Blues Jr. DOES NOT HAVE a digital reverb circuit or it would not have a tank. The Blues Jr. has a fully analog reverb, it just has a really, really crappy one that uses TLO7X chips instead of a proper tube driver (with driver transformer) and mixer circuit like a REAL Fender has.
Old 8th August 2020
  #19
Quote:
Originally Posted by kingofspain View Post
Unless I'm mistaken, the Blues Juniors reverb circuit is solid state, not digital.

https://elektrotanya.com/PREVIEWS/63..._sch.pdf_1.png

Like a lot of modern amps (the Vox AC30 CC2 included), it's driven by op-amps rather than valves, but it's still driving a good old fashioned spring tank.

Using op-amps is more effficient than valves, which waste a lot of energy generating the currents required to feed a spring tank, plus you loose the need for an extra transformer.
Whether one or the other is tonally superior is in the ear of the beholder - I'm ok with either.

I'll be happy to be corrected on this, but I think from an engineering point of view, op-amp is superior. I'd wager the reason a lot of high end amps still use valves to drive the reverb is less about tonal superiority, more to do with the mains transformer needing extra taps for to feed the op-amps the +/-15V.

More "efficient", possibly, although not enough to make a difference.

CHEAPER, HELL, yeah! one or two 25 cent chips in place of two tubes and a transformer, man, you can save a lot of money in quantity on that. It also sounds like utter crap if you hit it hard. TL0 series chips do not sound good clipped.

And, no, you don't need extra taps. All you need is a couple resistors (5 cents each) for a voltage divider. Dig it - it's REALLY EASY to get a low voltage from a higher one for next to nothing.The other way, no.

Cheap sh!t amps use cc reverb drivers. When you see those it's a sure sign of some pretty nasty cost cutting.

The are solid reasons that good amps use tube reverb. And there are reasons that SS circuits are common for beginner/practice amps.
Old 8th August 2020
  #20
Quote:
Originally Posted by plastic_ View Post
Forgive me if I’m stating the obvious but „drippy“ reverb is not the kind of effect you get with amp spring reverb.
You need an external reverb tank going in before the preamp, like a pedal.
No.
Old 8th August 2020
  #21
Quote:
Originally Posted by js1 View Post
I stuck an Accutronics tank in my AC15CC1, and it's better, but the results were not as good as I hoped. Still sounded cold.

And from an engineering point of view (I'm an old EE), op amps are not necessarily superior. Depends on the application.
What they are is versatile and cheap. Both in parts cost and manufacturing (automated assembly).

A tube reverb circuit is much more expensive, the tube alone costing more than entire op amp reverb circuit. There's a reverb driver transformer, so you don't save on iron.
Oh, god, another EE....

They do not teach guitar amps in modern EE courses. In fact they barely cover analog audio at all.

Chips do not sound good when clipping or even just driven hard. That means that in 90% of cases op amps do not work well in guitar amps. I can think of a couple exceptions (Music Man), but they're rare and were not cheap to make. And most companies that made them don't anymore. Wonder why that might be?
Old 14th August 2020
  #22
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davet's Avatar
 

Surf Guitar 101

These guys know what it takes to "drip".

https://surfguitar101.com/
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