Path: csiph.com!eternal-september.org!feeder.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: Don Kuenz Newsgroups: sci.electronics.design Subject: Re: How do those Spring Reverbs work in guitar amps? Date: Sun, 19 Mar 2017 05:08:19 -0000 (UTC) Organization: A noiseless patient Spider Lines: 62 Distribution: world Message-ID: <20170318b@crcomp.net> References: <50a79d86-0efd-4aa4-a5ac-2d26f4bedff8@googlegroups.com> Injection-Date: Sun, 19 Mar 2017 05:08:19 -0000 (UTC) Injection-Info: mx02.eternal-september.org; posting-host="dfac801a2ddc8f3f07148b03f30f4a3a"; logging-data="4594"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1+eavaOMi80YPldQGj+EJoA" Cancel-Lock: sha1:s56q0ef/JV1Rs2S/uKpbM4J6T8Y= Xref: csiph.com sci.electronics.design:452546 Phil Allison wrote: > olds...@tubes.com wrote: >> >> The Spring Reverbs inside guitar amps have always fascinated me, and I >> took them one step further by connecting one to my stereo years ago, and >> the sound was really cool! >> >> So, yea, I know the basic operation. According to one web article, there >> is a transducer at one end of a spring and a pickup on the other end. >> This caused the spring to vibrate and create the reverb effect. One >> group from the 1960s and 70s that really used them was the Ventures. (I >> have to mention that I love that groups music). Often when they play, >> you can actually hear them springs. >> >> I've taken them inside guitar amps and bnaged them, and they really can >> make a clatter. >> >> But what I am not finding is exactly what or how does this transducer >> work. Is it similar to a speaker coil? Or what goes on inside there? >> >> And the pickup, is that similar to a microphone, or what? >> >> There seems to be nothing that actually details the workings inside of >> them on the web. So, I thought I'd ask on here. >> > > ** The long springs transmit torsional waves, twisting back and > forward so must be driven the same way. Tiny tube magnets are made to > twist by the drive coil assembly while at the far end a near identical > transducer converts the twisting back to an electrical signal. > > The drive assembly is a kind of motor that makes the magnet rotate on > its axis about +/- 30degrees. A torsional wave travels fairly slowly > down a spring, making for long reverb times. > > A major benefit of this method is that external vibrations do not induce > torsional waves in the springs but only lateral ones and so are largely > rejected by the pick up assembly. > > AFAIK the idea was patented by Hammond in the late 50s - then made famous > by Fender in the 60s guitar amps. > > BYI I agree, it is not easy to find the above info on the net since the > Accutronics site disappeared. Your followup just now made me aware of that a company named Accutronics used to exist. There's a couple of spring reverbs in my bone pile. The metal tanks are stamped with "ACCUTRONICS GENEVA, ILL." The tanks originally came from PAIA as part of a kit: http://www.paia.com/proddetail.asp?prod=6740K http://www.paia.com/ProdArticles/hotspuse.htm This site seems like a good source of information: https://www.amplifiedparts.com/tech-corner/spring-reverb-tanks-explained-and-compared Thank you, -- Don Kuenz KB7RPU