How do you know what impedance a tank should have? Just for example, in the schematic below. Does the input impedance of the tank, need to reflect back through the tranny, and be appropriate for the AT7? And then, the output impedance needs to be of a value that will correctly drive the input of the AX7 that follows.?
Is that kind of what am amp builder has to figure out?
Thank You
http://www.el34world.com/charts/Schemat ... _AB763.pdf
Reverb Tanks
Moderators: pompeiisneaks, Colossal
Re: Reverb Tanks
For all Fender or any transformer driven reverb you want an input Z of 8 ohms and an output Z of 500-600 ohms.
When you get into higher Z impedance you assume solid state or capacitor driven reveb tanks.
The other coded numbers have to do with how many springs and length of delay. Choose those to suit your taste.
http://roymal.tripod.com/accutron.htm
When you get into higher Z impedance you assume solid state or capacitor driven reveb tanks.
The other coded numbers have to do with how many springs and length of delay. Choose those to suit your taste.
http://roymal.tripod.com/accutron.htm
Re: Reverb Tanks
I appreciate the info and the link.quayhog wrote:For all Fender or any transformer driven reverb you want an input Z of 8 ohms and an output Z of 500-600 ohms.
When you get into higher Z impedance you assume solid state or capacitor driven reveb tanks.
The other coded numbers have to do with how many springs and length of delay. Choose those to suit your taste.
http://roymal.tripod.com/accutron.htm
Thanks.....
Re: Reverb Tanks
With the tank's input impedance, impedance-matching is important for transformer driven tanks. With the output impedance, impedance-bridging is more important I reckon. JM2CW
-
Andy Le Blanc
- Posts: 2582
- Joined: Sat Dec 22, 2007 1:16 am
- Location: central Maine
Re: Reverb Tanks
you only have so many tube building blocks to choose from for the recovery.
A regular tube stage will match a moderate input impedance to a moderate or high impedance.
A cathode follower will match a high input impedance to moderate or low impedance's.
A grounded grid (cathode input) will match low input to moderate or high output impedance.
You see the various inputs, a SE OPT to drive very low imp(fender), and cap coupled driving
moderate imp tanks (Ampeg), sometimes you'll find a follower driving the input like in a univox with a SRPP, or an Alamo with a 6U8A..
At the recovery you mostly see a regular gain stage, maybe a transistor (Sunn),
some magnatones had a grounded grid followed by a gainstage, It matches
to the tank a bit better than just a regular stage and provides RF sheilding
but has little positive gain.
It really comes down to the economy of the feature, how many gain stages you can afford to invest.
I really like the magnatone and ampeg revebarocket rigs but they require
more gain stages, which mean also a greater investment in the PT.
The best use of materials and stages I've seen so far was an Alamo.
It had a 6u8a driver, a pentode gain stage and follower in one tube.
A lot of gain that could be used independently of the rest of the pre amp.
The recovery was a transistor that was powered from the cathode bias off the power tubes.
A regular tube stage will match a moderate input impedance to a moderate or high impedance.
A cathode follower will match a high input impedance to moderate or low impedance's.
A grounded grid (cathode input) will match low input to moderate or high output impedance.
You see the various inputs, a SE OPT to drive very low imp(fender), and cap coupled driving
moderate imp tanks (Ampeg), sometimes you'll find a follower driving the input like in a univox with a SRPP, or an Alamo with a 6U8A..
At the recovery you mostly see a regular gain stage, maybe a transistor (Sunn),
some magnatones had a grounded grid followed by a gainstage, It matches
to the tank a bit better than just a regular stage and provides RF sheilding
but has little positive gain.
It really comes down to the economy of the feature, how many gain stages you can afford to invest.
I really like the magnatone and ampeg revebarocket rigs but they require
more gain stages, which mean also a greater investment in the PT.
The best use of materials and stages I've seen so far was an Alamo.
It had a 6u8a driver, a pentode gain stage and follower in one tube.
A lot of gain that could be used independently of the rest of the pre amp.
The recovery was a transistor that was powered from the cathode bias off the power tubes.
lazymaryamps