So far I was just browsing through this forum. There is so much great knowledge available Thanks a lot!
Now my Q:
a friend of mine has a Music Man RD-112 65W amp and since it has a solid state premap he's obviously is not impressed by it's overdriven sound. Here's the schem btw: http://www.ernieball.com/mmonline/techi ... 100-rd.pdf
So my idea was to build a Hyb A preamp for him for getting a nice overdrive. My main electronic experience is with stompboxes (see http://www.diystompboxes.com/smfforum/i ... ?board=2.0 ) but I also built an Alembic preamp clone I use permanently with my bass guitars. So I'm not a complete newbie to high voltages.
So what do you guys think of my idea? Complete rubish?
Did you feed the Hyb A preamp into the send/return loop of the Music Man?
Markus
My Music Man doesn't have an effects loop so I couldn't do that. It might be worth a try. Music man amps tend be be excellent transplants for an ODS of any type.
There is a company called "Menatone" that builds such a pedal, it's called a "Howie" I used to have one, sounded great through my 67 Twin Reverb! There used to be a schematic out there for just such a pedal but I couldn't find it. I think you simply sub JFET's for each triode of the 12AX7's and of course adjust your power supply for 9-18 vDC.
Funkalicousgroove wrote:There is a company called "Menatone" that builds such a pedal, it's called a "Howie" I used to have one, sounded great through my 67 Twin Reverb! There used to be a schematic out there for just such a pedal but I couldn't find it. I think you simply sub JFET's for each triode of the 12AX7's and of course adjust your power supply for 9-18 vDC.
Hybrid Rev A seems the favorite, closely followed by HRM (i.e. an amp which has a post-OD tone stack). I like the 70s version, too.
If you want the amp to be capable of a sustaining lead sound then Hybrid Rev A is a good start. The HRM amp can give you a very nice clean crunch tone with both tone stacks engaged or a bit more of a Marshally tone by bypassing the first tone stack with the preamp boost.
Since I do the crunch tones with pedals and want a fat singing tone from the amp's lead channel I prefer the non-HRM amps.
Dave Allen www.allenamps.com used to sell a 2 12AX7 pedal Kit with a power transformer that will support up to 3 dual triode novial type tubes, I know he has the trannies, not sure if he still has the boxes, also try www.hoffmanamps.com he sells provisions for just such a project.
Hybrid Rev A seems the favorite, closely followed by HRM (i.e. an amp which has a post-OD tone stack).
If you want the amp to be capable of a sustaining lead sound then Hybrid Rev A is a good start.
Seems like I found the version
Dave Allen www.allenamps.com used to sell a 2 12AX7 pedal Kit with a power transformer that will support up to 3 dual triode novial type tubes, I know he has the trannies, not sure if he still has the boxes, also try www.hoffmanamps.com he sells provisions for just such a project.
Thanks!! Will have a look for sure.
I thought about using a 18V AC wall wart and a toriodal 230V to 12V wired up reversed. Should give enough voltage. The heaters could be powered directly from the 18VAC via a 12V DC regulator.
Is this a good idea or would it be better to have a "normal" toriodal with separate heater and high voltage? From what I read at diystompboxes puretube used this "reversed toroidal" method for his EH tube pedals and it seems that going this way reduces hum.
markusw wrote:
and a toriodal 230V to 12V wired up reversed. Should give enough voltage. The heaters could be powered directly from the 18VAC via a 12V DC regulator.
Is this a good idea or would it be better to have a "normal" toriodal with separate heater and high voltage? From what I read at diystompboxes puretube used this "reversed toroidal" method for his EH tube pedals and it seems that going this way reduces hum.
Hi Markus:
I've got a fair amount of experience hooking up transformers reversed. The only caution I can think of is that they will usually run a little hotter. I don't know particularly why this is. One would think that KVA in = KVA out but perhaps it's the orientation of the windings with regard to outside v.s. inside and access to cooling. The other observation concerns large air cooled transformers. They will make more noise when hooked up backwards. The transformer itself hums louder. I don't know about the output waveform and hum transmitted through the filter.
Try it.
Dan
The Last of the World's Great Human Beings
Seek immediate medical attention if you suddenly go either deaf or blind.
If you put the Federal Government in charge of the Sahara Desert, in five years time there would be a shortage of sand.
I've got a fair amount of experience hooking up transformers reversed. The only caution I can think of is that they will usually run a little hotter. I don't know particularly why this is. One would think that KVA in = KVA out but perhaps it's the orientation of the windings with regard to outside v.s. inside and access to cooling. The other observation concerns large air cooled transformers. They will make more noise when hooked up backwards. The transformer itself hums louder. I don't know about the output waveform and hum transmitted through the filter.
Thanks for your information! Do your observations also apply to toroidals?
Forgot before: could someone please target me to a schem of the HRM?
I would opine (guess) that the noisy winding would probably not translate to the toroid type. There isn't as much to rattle. The windings are wound around a ferrite/ceramic core instead of stacked iron plates. The windings are still going to move against each other though.
If you are into experimenting you may become the guru on this issue. Hook up the tx forward with a full resistive load and take it's temperature after a few hours. Repeat the experiment with the tx wired backwards. Let us know.
I use a bank of 25 watt 1k resistors for such things. You can select your experimental load using ordinary alligator clip jumpers. It's very handy for checking power supplies under load.
Dan
The Last of the World's Great Human Beings
Seek immediate medical attention if you suddenly go either deaf or blind.
If you put the Federal Government in charge of the Sahara Desert, in five years time there would be a shortage of sand.
skyboltone wrote:I would opine (guess) that the noisy winding would probably not translate to the toroid type. There isn't as much to rattle. The windings are wound around a ferrite/ceramic core instead of stacked iron plates. The windings are still going to move against each other though.
If you are into experimenting you may become the guru on this issue. Hook up the tx forward with a full resistive load and take it's temperature after a few hours. Repeat the experiment with the tx wired backwards. Let us know.
I use a bank of 25 watt 1k resistors for such things. You can select your experimental load using ordinary alligator clip jumpers. It's very handy for checking power supplies under load.
Dan
Thanks again for your information!
Will try to compare hum and temperature once I get started with my build
So far my experience on using xfmrs hooked up reversed is pretty limited. For my Alembic clone I used a 230V to 12V and a 230V to 6V which was hooked up reversed and fed with 12V. They were both PCB mounted "standard" xfmrs and there is more or less no hum. Maybe because they are potted? http://en.produkte.era-online.de/produk ... pl_ei42/01
One more Q: when loking at the Music Man schem again (first one in the pdf) I found that the two volume pots that immtately follow the "Hi" return jack are 10k. So running the ODS preamp output into the "Hi" return jack is probably not a good choice considering that the ODS output caps are not that large. Might it be better to feed the ODS preamp into the "Lo" return jack since the pots that follow it are 100k or 1M depending on the channel.
However, in this case the pots are wired in series with the signal.
Any ideas
Thanks a lot!
