Spring reverb transducer repair possible? (and does it make sense?)

[rock soderstrom]

Hi guys, I am a spring reverb lover and collect spring reverb tanks.

I have been given some defective ones over time. Sometimes just the thin connecting wires to the RCA sockets are broken, a simple repair.

But unfortunately often the transducer coils are open. With the "made in USA" Accutronics I have, it is always the red output transducer coil. No idea why, coincidence? I'm afraid there is a reason. What do you think?

As an example here a 9AB2A1B, the red coil shows again no continuity.
Is it possible to repair this, does anyone have experience with this?

The transducer coil as a spare part will not be available, right?

I could remove the corresponding coil from other similar Accutronics tanks, unfortunately all defective ones in my environment are broken exactly at this point.

What can I do? Rewind?

 

[Whoops]

What can I do? Rewind?

I repaired some of those in the past...
If I remember correctly you have just 1 coil, so 2 wires.
The wire is so thin that sometimes it breaks near the connector where it's soldered to.
Easy fix is , take the tape out and unwind 1 turn of the broken wire, then remove the varnish of the coil wire (burn it with a lighter) and solder tin it. Install the tape and resolder the wire to the connector.

If the coil is shot, like burned, remove the wire while counting all the turns, write the number of turns and then wind it with the same wire gauge as the original and the same number of turns.

hope this helps

 

[JW]

Hmmmm. Off topic, but this post makes me realize spring reverbs aren't something this community has DIY'd much? Would be super amazing to somehow DIY one of those AKG box thingys. BX10 or whatever. Why did I get rid of that? Kicking myself again.

 

[Whoops]

Hmmmm. Off topic, but this post makes me realize spring reverbs aren't something this community has DIY'd much?

There's different DIY projects all involving the use of Accutronics reverb tanks.
Being it a Fender Tube spring reverb clone, or just using an IC based driver and recovery circuit for the tank

Would be super amazing to somehow DIY one of those AKG box thingys. BX10 or whatever. Why did I get rid of that? Kicking myself again.

That would be great for sure, but a really big endeavor due to the complexity of those specific mechanical spring circuits as found in the BX20 and BX10. It would be really hard to DIY.

I've seen people DIY amazing big Plate reverbs, in the vein of the EMT 140, but although really big/massive the mechanical parts are pretty simple when compared to an AKG BX20/10 unit

Check this out:

 

[Tubetec]

The higher the Z of the transducer , the finer the wire , most often its the pickup transducer that goes O/C in my experience ,the 10k impedence pickup transducers are most likely to die due to the very fine wire used

The coil can be stripped and re-wound , if its lo-z like an 8 ohm drive end transducer that easy to wind by hand , 40 odd gauge wire is possible but its a delicate job , you'd need a varispeed pickup coil type winder .

 

[JW]

That would be great for sure, but a really big endeavor due to the complexity of those specific mechanical spring circuits as found in the BX20 and BX10. It would be really hard to DIY.

You mean it's not as easy as just throwing a couple accutronics tanks in a vat of peanut oil and hoping for the best?

 

[mjrippe]

You mean it's not as easy as just throwing a couple accutronics tanks in a vat of peanut oil and hoping for the best?

Check out these shots of a BX-20 on my old web site:
https://analogaudiorepair.com/2013/05/03/akg-bx20-spring-reverb/Craziest spring mechanism I have ever seen.

Note that since that post someone here has recreated the coils, though it is an extremely delicate job to replace them.

 

[JohnRoberts]

I recall as a manufacturer using truckloads of spring reverbs because that was the cost effective technology back then. When we first moved guitar amp production to China (last century) the Chinese did not know how to make a spring reverb that didn't suck so we had to ship US springs to China until they learned how.

These days there may be some nostalgia value.. YMMV

JR

PS; I recall how nice it was when digital efx became cheap enough to replace cheap springs in top box powered mixers.

 

[rock soderstrom]

PS; I recall how nice it was when digital efx became cheap enough to replace cheap springs in top box powered mixers.

That's how it was back then, digital was just better. Even devices that were fully analog had "digital" on their front panel.

In terms of flexible room simulation, the digital devices were (and still are) far superior to the analog ones, without a doubt.

Nevertheless, spring and plate reverb have undeniable musical qualities, not only from a nostalgic perspective.

Artificial rooms define virtual localities with a special character, the events sounding in them somehow become larger than life.

I love the archaic sound of spring tanks on voices, guitars, snares and especially synthesizers. It has such a rough texture that still can't be completely simulated from my point of view.

Spring reverbs are one trick ponies by nature, the sound signature is largely static, meaning you have to select the particular tank for your sound. That's why you can't have enough of them...

 

[AnalogPackrat]

You also can't kick a digital simulation at the end of your spanking surf solo.

 

[rock soderstrom]

The higher the Z of the transducer , the finer the wire , most often its the pickup transducer that goes O/C in my experience ,the 10k impedence pickup transducers are most likely to die due to the very fine wire used

I think you are right here, even though most accutronics receiver transducer have an impedance of just over 2k.

I will, when I have some time to analyze my defective reverb spring in more detail, unwind the output coil.

I will keep you posted...

 

[ccaudle]

You also can't kick a digital simulation at the end of your spanking surf solo.

All new rage: adding an accelerometer to a modeling amp so you can get the microphonics and spring tank kick response modeled correctly.

 

[AnalogPackrat]

For realism we'll need a six axis device.

 

[Saransk93]

Not all "spring" reverb tanks work the same. VOX, and Thompson-VOX (US)< didn't want to pay the licensing fee for the typical Accutronics reverb tanks so they uses a setup with two crystal phono pickups to drive and receive the signal.
The AC30 used an ACOS GR71 with the spring attached to the needle
I believe this was used all through the JMI period.

 

[rock soderstrom]

Not all "spring" reverb tanks work the same. VOX, and Thompson-VOX (US)< didn't want to pay the licensing fee for the typical Accutronics reverb tanks so they uses a setup with two crystal phono pickups to drive and receive the signal.
The AC30 used an ACOS GR71 with the spring attached to the needle
I believe this was used all through the JMI period.

Thanks for info. How well do this crystal phono pickup tanks sound compared to the ordinary accutronics style reverb tanks?

 

[Lawrocker]

Check out these shots of a BX-20 on my old web site:
https://analogaudiorepair.com/2013/05/03/akg-bx20-spring-reverb/Craziest spring mechanism I have ever seen.

Note that since that post someone here has recreated the coils, though it is an extremely delicate job to replace them.

Woooow. I made a remote visit to a client in another city. One side of his BX-20 had audio going in, but nothing coming out. Looking at what it seemed to take to get at the innards, I had to leave it. Looking at these photos, I made the right choice. I could do it in my shop, but it isn't a one day on-site thing.

 

[57sputnik]

You can buy replacement Accutronics assemblies from CE electronics.

The coil wires are very fragile. If Molex connectors were plugged onto the leads, unplugging them can often break the magnet wire.

This is my DIY reverb: MicMix MasterRoom XL-305 Spring Reverb Clone - Pro Audio Design Forum

MasterRoom XL-305 Clone Sleds

The XL-305R is now being made by Audio-Scape: XL-305R Equally Tempered Stereo Reverb — Vintage Pro Audio Equipment | AudioScape Engineering Co.

 

[Tubetec]

I 'm a major proponent off driving your reverb tank off the speaker output of your tube amp ,via a variable attenuator .
never mind recovering the reverb through the amp and mixing it back with direct signal , take it back to the mixer or Daw via a mic amp or DI if its a high z transducer , record it as two seperate tracks .
One direct mic off the cab , the other a clean feed from the tank

 

[Nick Nack]

That's how it was back then, digital was just better. Even devices that were fully analog had "digital" on their front panel.

Headphones!

 

[CJ]

I used to rewind those hi z reverb transducers, pain I'm the rear. They rivet the coil/core assembly to the plastic carrier
I find that after rewinding and reassembly that the pan sound is weaker. This is probably from the stress the Ni lams go though when bending them to get the coil off. Since Mod pans are cheap, much better to buy new pan. I also like the crazy noisy piezo pans used in the Silvertones.
For some reason, the wire tension got real tight on the accutronics pans, that, coupled with using a different potting compound which hardens real stiff has led to the demise of around 20 pans that I have replaced
Most of the Fender black face twin reverb tanks that I have seen are still kickin, probably due to wax being used.
Man the whole band got drunk tonight and embarrassed the hell out of me being the only straight guy, I don't t know about this rock and roll biz