reverb tank impendance

[bagudan]

Hi. I have an accutronics 4fb3d1b lying around. It´s got an input impendance of 1475 ohms. Can I somehow work my way around this,so I can make it a tank with an input around 300 ohms (stage center reverb)?
Thanks

[sean k]

I think you'd be able to find a 1.5k/600 ohm transformer with a centre tap of the 600, which will with the centre tap grounded give you 300, oops, nope that'll give you 150 actually... so a 3k/600ct will do it. That said there are driver configs out there that'll drive a higher impedance and it's somewhat easier as you don't need as much current to drive it. I think your better off driving 1.5k than having to dig up more current to drive 300 ohms.

[bagudan]

Ok. That makes sense. So am I looking for another cirquit than the stage center reverb? or is it possible to do modifications to the SCR cirquit to make it work?

[markeebee]

I've got one of those as well. Tanks with similar impedance were used in Musicman amps - the reverb circuit in them is quite simple, I think you could fudge a stompbox quite easily:

http://www.schematicheaven.com/newamps/musicman_2165-rd_&_2100-rd.pdf

Alternatively, you can use the tank with a valve driver without having to use a transformer. Check out "cheap current source drivers" about two-thirds down the page:

[http://www.freewebs.com/valvewizard2/reverbdriver.html

[sean k]

I'd say you'd most probably not have any problems using the stage centre reverb to drive the 1.5k tank and it may even drive a higher impedance better than it does the lower impedance tanks. That sais if you want something a little more complicated then this looks pretty good.

It was already on the GGG page. Oops, it's got +15/-15 power. I was looking into this stuff a while back and found something I was going to use but I can't find the links. Oops again, it was also on the GGG page.

[Rob Strand]

I'd say you'd most probably not have any problems using the stage centre reverb to drive the 1.5k tank and it may even drive a higher impedance better than it does the lower impedance tanks. That sais if you want something a little more complicated then this looks pretty good.

++++1

There's nothing in the original circuit which forces it to "match" 300ohm.
In fact I'd say at 300ohm the original is pushing the opamp drive circuit.

It certainly doesn't hurt to fine tune the drive circuit gain and receive circuit gains on any reverb circuit.

[petemoore]

  What about takin' a big 'ol Mosfet transistor to transfer the SCR's output voltage swings with a bit more current driving capability, power mosfet/source follower driving the coil ?
 Seems like I did that and the low-boosted notes remained more defined, my recollector is a bit clunky on that...it was kinda big, and then this 5w tube amp started being the driver/recovery unit, then the tube sockets started needing replaced...I'll have to get that SCR out again.