Integrating multiple impulse-response recordings from the same source can further reduce the noise floor. The circuit is meant to be based on a 'Howland current pump', and while these can be made to work very well, the results may be unpredictable if you don't know how to set it up properly. It is actually quite difficult to drive properly. In fact, they work so well that, when sampling or convolution reverb made it possible to 'copy' reverb from actual spaces, many people found that it didn't sound exciting enough for pop music, so turned the process to sampling pieces of reverb hardware. There are many delay plugins out there that can do some of the obvious short delay stuff that this plugin can do, but sometimes less is more. I used a woofer tester normally used for measuring the Thiele-Small parameters of loudspeakers to do the impedance graph.
Note that in the circuits shown below, I have used standard polarised electrolytic capacitors, including in locations where there is no polarising voltage. As the drive coil impedance rises further, the voltage needed to drive the coil exceeds that available from any common cheap opamp. . The current is limited by the power supply rails, divided by the tank Zin. Rockfield Studio in Wales even had a room made with suspended glass plates to create a variable reverberant environment.
This is important to ensure maximum headroom. This simple circuit has a deliberately limited output impedance, and the constant current characteristic only extends to about 6. The larger the plate, the longer the reverb time — but these things were big, clumsy and heavy. This will allow the output, or recovery amplifier gain, to be reduced, lowering possibilities of feedback and minimizing microphonics. Some guitarists might like to experiment with using a second small amp and speaker just for the reverb - it's an interesting sound. It also includes novel features such as a fully automatable Shake control that will shake the virtual springs around for those thunderous spring effects. Using half of the winding doesn't mean the impedance is nominally 500 ohms - it actually ends up being only 250 ohms, ¼ of the impedance of the full winding.
If you make a sound in a room then that sound will reflect back to you, not just from the walls but by objects in the room. Are there parasitic impedances, or electro mechanical effects that make the input impedance change in a way different than the simple math? See below for more on that topic. So it's quite common use convolution reverb to accurately get the sound of an actual plate into your mix. Most opamps can provide up to ±20mA peak , but that is usually a measure of the short circuit current. After getting a new 8 ohm tank for some experiments and to take a few measurements, it turns out that the coil can be driven somewhat harder than claimed. With a 600 ohm drive coil, the transformer's nominal impedance at 1kHz will be about 20 ohms in theory, but the way the transformer is made might cause that to be somewhat different these are hardly precision components.
An addition to the original circuits is C3 in Figures 5, 7 and 14. The transformer is used in reverse, so the 'primary' is used to drive the reverb tank and the 'secondary' is used as the primary. I'd like to thank 'PhAbb' for suggesting the use of one of the el-cheapo 1k:8 ohm transformers to drive high impedance coils. With Repeater preset on mix bus. In this case, R5 22k is effectively in parallel with the coil, although it may not look like it at first glance.
While it may not evoke the sense of a concert hall or a nice sounding room, it does offer a quality of resonance that's desirable on many tracks. As a result, it is possible to replace even extremely old tanks if necessary, and a direct replacement is almost always available. Yes, of course it's overkill, but the added cost is actually quite small. While it is possible to get good low frequency performance, it's generally undesirable because it tends to muddy the sound too much. You adjusted the reverb level simply by increasing or decreasing the sound going into the room. In order to reproduce the build-up in complexity in the decaying reverb tail, multiple re-circulating filters usually a mixture of comb filters and all-pass filters were used, sometimes fed from the original input, sometimes from the outputs of the tapped delay line, depending on the designer. A measurement of inductance for example gives a very different value from that calculated, but an impedance scan shows that the quoted figures are fairly close.
The most famous of the digital reverb manufacturers is probably Lexicon, who defined the pop reverb sound of the day with their 224 model. The circuit's gain will be constantly changing, depending on the input level. Convolution is essentially a brute-force, number-crunching means of producing reverb or other linear delay-based treatments which is brilliant in its simplicity. Originally released in 1963, Super Reverbs were all tube designed amps with a spring reverb in it. Because the plate is rectangular and the sound waves propagate in a circular manner, even the first wave of reflections is very complex, as the expanding wavefront will encounter different parts of the edge of the plate at different times. With the values shown, the limiter will be at the limiting threshold when the 'Compression' pot is at maximum resistance and with an input voltage of around 150mV.
Specific information available on each instrument's page. Probably the first successful artificial reverb device was the spring, though all kinds of weird and wonderful devices were created, including coiled pipes with a speaker at one end and a mic at the other. To capture the sonic signature of an electronic reverb unit, the same test signal can be fed through it and then mathematically processed to produce an impulse response, enabling that particular hardware setting to be recreated with almost perfect precision within a convolution reverb system. Digital Methods: There are many methods of creating reverberation, both digital and analog. The advantage is that it's easier to reproduce a suitable signal level for measurement, and because the measurement is integrated over a few seconds it tends to be less susceptible to corruption by low levels of background noise in the room being sampled.