I'm looking for SS HV (mosfet ?) transformerless reverb schematic - anyone ?

[kagliostro]

I'm looking for Solid State high voltage (mosfet ?) reverb schematic (to be used in tube amp)

anyone has a link ?

Thanks

K

EDIT: I apologize, I omitted to say that I'm looking for a Transformerless SS High Voltage reverb schematic

[sluckey]

Sorry I couldn't provide more help. 

So, what's your point???

[Ritchie200]

Hey K!

I do have a suggestion, but it may not be what you are looking for...  However, if you can wire up a 15v supply (I know, not very "High Voltage"!), this might be a simple add-on.  PAIA sells a kit called the Hot Springs Reverb.  It is a Craig Anderton design that is quite unique.  It uses two tanks in a humbucker type setup that supposedly cancels out all the boinging and other noise that happens with a single tank.  I have looked on with interest for several years, but never had an application for it.  It does have good reviews and is simple to build with a quad op-amp taking care of the send/recover duties.  I dont know if you could make it from scratch cheaper than buying the kit.  You will also need to add a mixer circuit to this.  It is meant for a rack, but I have read where people have put them in amp builds - like any tank, you have to watch where and how you mount them.  

Jim

Link to site:
http://www.paia.com/proddetail.asp?prod=6740K

Link to manual/article explaining operation with parts list:
http://www.paia.com/talk/viewtopic.php?f=6&t=90

[TIMBO]

Hi K, Some fun stuff for you.  

Found it here http://www.blueguitar.org/new/articles/other/mikede30.pdf

[kagliostro]

Many thanks to all

SORRY I forgot to say a thing

the schematic posted by TIMBO is very interesting

but I'm looking for a Transformerless SS Reverb

I apologize, in this last time often happen to me to omit something in my discourse  

K

[kagliostro]

Thanks

but my interest is more about a "conversion" of one of this reverb circuit in a SS reverb circuit


K

[kagliostro]

I hope now you can see the schematics correctly

K

[kagliostro]

Thanks

And Happy New Year

Franco

[PRR]

> looking at this link

? ? ? That's a Tremolo. Franco is looking for reverb:
"I'm looking for SS HV (mosfet ?) transformerless reverb schematic - anyone ?"

[kagliostro]

Yes, as PRR say I'm looking for a HV SS (mosfet) reverb

however thanks Drgonzonm

that circuit is anyway of interest 

Franco

[Willabe]

4. In the reverb circuits, the transformers are SE,  I am wondering whether PP transformers could be used.  (Additional circuitry, and a PI.

Sure. The standard Fender verb circuit could be PP but I don't think that will help K for what he wants.


           Brad      

[PRR]

I just saw this. It is low-voltage high current, but is transformerless FET.

http://surfybear.weebly.com/new-pcb-and-kit.html
http://surfybear.weebly.com/fet-reverb---project.html
http://surfybear.weebly.com/uploads/1/3/6/2/13625127/surfybear-jfet-reverb.pdf

> high voltage ... reverb

Reverb springs are low-voltage high-ish current. Say 1V 100mA. Maybe 10V 10mA for the higher impedance tanks.

The most sensible way to drive them from a high-voltage supply IS an audio transformer.

[kagliostro]

Thanks DrGonzom & PRR

The examples that I've find effectively are all using a penthode, not a triode

but I was hoping that a Mosfet version can be build

As PRR say

Reverb springs are low-voltage high-ish current

and may be this is a reason as we don't see a Mosfet HV version

Thanks

K

[sluckey]

Franco, here's a cap coupled reverb circuit that's driven by parallel triodes. This circuit is from my Magnatone M10-A and sounds very good. Maybe this can be a model for your MOSFET quest. Notice the 10 watt plate resistor? As PRR said, this is a current hungry driver.

I'm thinking that some of the FETs used in the VVR circuits could be used in this  circuit.   

[kagliostro]

Grazie Steve

and I'm sure at 99% I've seen your schematic before now, only I didn't remember it 

I'll save your cut image in my reverb schematic collection

As is possible to substitute a triode with a mosfet, like Mosfet Follies show

http://www.geofex.com/Article_Folders/mosfet_folly/mosfetfolly.htm

may be this your schematic can be converted to be build with mosfet

I think I can go on a bit more on searching

Many Thanks

Franco

[Willabe]

I was just reading the accu bell sound web site.  Apparently, the reverb tank needs to SE, to maintain tension on the springs.

What?  

Kevin O'Connor has a PP reverb circuit in TUT1 (or 2) and  TUT5 and sells the transformer for it on his store web site.

As long as the reverb transformer feeds the tank the right ohms/current/voltage it can't tell if it's coming from a SE or PP primary.


           Brad    

[kagliostro]

Also I've read something on TUT about a PP transformer for reverb

I'm not sure

but may the reason be the fact that an SE is more prone to Humm

missing the cancellation present in PP circuit ?

K

[kagliostro]

Would be so nice if it were that simple 

K

[sluckey]

That IFR820 will handle a lot of current. You would not need two in parallel to drive the reverb tank.

[kagliostro]

After a read on the Mosfet Follies

I think that the more difficult circuit to be arranged with the mosfet

is the recovery circuit

about the CF (SourceFollower) I think is more easy to obtain something

but as I understand near nothing about SS may be I'm saying something of stupid

Franco

[PRR]

> That IFR820 will handle a lot of current.

Also a LOT of input capacitance. 5X-10X more than we ever expect into a tube grid. About as much as the 500pFd coupling capacitor often found in a tube reverb driver.

500-1000pFd across the tank output will take all the shine (>3KHz) away. Worse it is likely to resonate with tank inductance and give an annoying ringing. The recovery amp really should be a small JFET on 25V supply.

[kagliostro]

A guy of an italian forum was asking for that thing, so I and one other guy developed some interest in the matter

We were wondering if the thing is feasible as a low cost mod to an existing amp to add to it an old style spring reverb

Nor I or the other guy are enough skilled to draw something in this sense and so I asked about

Till now we didn't find a schematic do that way, so I think that this wasn't a good idea and isn't feasible

Many Thanks for the interest and answers

K

[kagliostro]

Hi Drgonzonm

I see you've great interest in this thing

I have a bit tempered my enthusiasm about this thing as it seems that it isn't so simple

and may not doable

I Know the experiments that Tubenit has done about the use of IRF820 as Source Follower (CF)

and also in bootstrap configuration and I've find it very interesting

But about transformerless SS drive now I doubt

Ciao

Franco

[smackoj]

Very interesting discussion. Muy interesante K, gracias por el questione.