Hoffman Amplifiers Tube Amplifier Forum
Other Stuff => Solid State => Topic started by: kagliostro on December 29, 2013, 04:13:53 am
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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
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Sorry I couldn't provide more help.
So, what's your point???
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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 (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 (http://www.paia.com/talk/viewtopic.php?f=6&t=90)
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Hi K, Some fun stuff for you. :icon_biggrin:
Found it here http://www.blueguitar.org/new/articles/other/mikede30.pdf (http://www.blueguitar.org/new/articles/other/mikede30.pdf)
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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 :worthy1: :worthy1:
K
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Thanks
but my interest is more about a "conversion" of one of this reverb circuit in a SS reverb circuit
K
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I hope now you can see the schematics correctly
K
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Thanks
And Happy New Year
Franco
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> looking at this link
? ? ? That's a Tremolo. Franco is looking for reverb:
"I'm looking for SS HV (mosfet ?) transformerless reverb schematic - anyone ?"
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Yes, as PRR say I'm looking for a HV SS (mosfet) reverb
however thanks Drgonzonm
that circuit is anyway of interest :thumbsup:
Franco
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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 :icon_biggrin:
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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/new-pcb-and-kit.html)
http://surfybear.weebly.com/fet-reverb---project.html (http://surfybear.weebly.com/fet-reverb---project.html)
http://surfybear.weebly.com/uploads/1/3/6/2/13625127/surfybear-jfet-reverb.pdf (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.
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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
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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. :dontknow:
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Grazie Steve
and I'm sure at 99% I've seen your schematic before now, only I didn't remember it :rolleyes:
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 (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
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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 :icon_biggrin:
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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
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Would be so nice if it were that simple :icon_biggrin:
K
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That IFR820 will handle a lot of current. You would not need two in parallel to drive the reverb tank.
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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
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> 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.
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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
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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
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Very interesting discussion. Muy interesante K, gracias por el questione.
:icon_biggrin: