Hi all I have a question for ya.
If I build a guitar amp is it ok to use ultra linear configuration?
And also If I build the output stage with a higher then needed output transformer will this have any effect on removing distortion created by the preamp?
I know this is probably a stupid question just not sure.
Thanks for the help.
Nick
If I build a guitar amp is it ok to use ultra linear configuration?
And also If I build the output stage with a higher then needed output transformer will this have any effect on removing distortion created by the preamp?
I know this is probably a stupid question just not sure.
Thanks for the help.
Nick
Nick-
If you want to get distortion (ie blues-y or more) from your guitar amp- and most of us do- it's probably better to stay away from 'hifi'-type circuits, like UL. However, it could be an interesting experiment.
When you say 'higher than needed' output transformer, are you referring to the primary impedance or the power rating?
Too-high impedance will reduce output and lose some of the 'tubey' sound .
A higher power-rated transformer won't give the same distortion characteristics as a smaller unit but may be smoother- which could be a good thing.
It's only a guitar amp- just use what you have and do some experimenting.
Cheers
John
If you want to get distortion (ie blues-y or more) from your guitar amp- and most of us do- it's probably better to stay away from 'hifi'-type circuits, like UL. However, it could be an interesting experiment.
When you say 'higher than needed' output transformer, are you referring to the primary impedance or the power rating?
Too-high impedance will reduce output and lose some of the 'tubey' sound .
A higher power-rated transformer won't give the same distortion characteristics as a smaller unit but may be smoother- which could be a good thing.
It's only a guitar amp- just use what you have and do some experimenting.
Cheers
John
Sorry I didn't mention it I meant the primary impedance of the output transformer.
I was planning on using an edcor push pull transformer for a circuit with 4 el34's and the impedance in 5k which is about 2k high. I know it will drop the output power just wondering about anything else.
I wanted to try it in ultra linear just for the sake of simplicity, you know one less voltage to come up with.
Thanks for the help,
Nick
I was planning on using an edcor push pull transformer for a circuit with 4 el34's and the impedance in 5k which is about 2k high. I know it will drop the output power just wondering about anything else.
I wanted to try it in ultra linear just for the sake of simplicity, you know one less voltage to come up with.
Thanks for the help,
Nick
Hey Nick,
I would just use a large dropping resistor (1K -4.7K 5 to 10W rating) to get the screen voltage you need for the EL34, that is pretty much what everyone does anyway. 22uF cap will probably provide enough filtering to keep hum reasonably in check, and should allow for some nice quick sag as the screens start to draw some current.
UL has been used in some obscure accordian type amps (Gretsch??) and I have heard some diy amplifiers using it, and you won't be surprised to hear that IMO poorly regulated pentode sounded much better, nice sustain and crunch, UL just seemed to clip a lot harder and sounded bad.
Avoid the temptation to do your usual overkill psu, you want poor regulation in this supply. Check out some of the old Marshall EL34 designs for some inspiration.
If that edcor has an 8 ohm tap just connect a 4 ohm speaker load to it and you will reflect about 2.5K to the primary which is in the right range.
I haven't been posting much as my current consulting job keeps me really busy.. Nice to have work in this economy.
I would just use a large dropping resistor (1K -4.7K 5 to 10W rating) to get the screen voltage you need for the EL34, that is pretty much what everyone does anyway. 22uF cap will probably provide enough filtering to keep hum reasonably in check, and should allow for some nice quick sag as the screens start to draw some current.
UL has been used in some obscure accordian type amps (Gretsch??) and I have heard some diy amplifiers using it, and you won't be surprised to hear that IMO poorly regulated pentode sounded much better, nice sustain and crunch, UL just seemed to clip a lot harder and sounded bad.
Avoid the temptation to do your usual overkill psu, you want poor regulation in this supply. Check out some of the old Marshall EL34 designs for some inspiration.
If that edcor has an 8 ohm tap just connect a 4 ohm speaker load to it and you will reflect about 2.5K to the primary which is in the right range.
I haven't been posting much as my current consulting job keeps me really busy.. Nice to have work in this economy.
I had thought about putting half the load on the secondary of the out put. That good to know about using it in ultra linear, I won't do it.
I'm basically going to clone a rather obscure guitar amp,one I can't afford LOL . It's a Orange GRO 100.
Here's a link to a schematic
http://www.schematicheaven.com/newamps/orange_gro_100.pdf
I like the amp and I also like the simplicity of the design. Just trying to find the secondary specs of the power transformer though to see if one I have on hand will work.
As you can see the power supply has decent filtering for a guitar amp, I have found most of the expensive one at least have clc filter network.
Nick
I'm basically going to clone a rather obscure guitar amp,one I can't afford LOL . It's a Orange GRO 100.
Here's a link to a schematic
http://www.schematicheaven.com/newamps/orange_gro_100.pdf
I like the amp and I also like the simplicity of the design. Just trying to find the secondary specs of the power transformer though to see if one I have on hand will work.
As you can see the power supply has decent filtering for a guitar amp, I have found most of the expensive one at least have clc filter network.
Nick
nhuwar said:
Despite the stack electrolytics in the power supply you can see that there is a 450V cap at point B and probably less than 4mA of plate current total to the rest of the pre-amp and driver circuitry - figure not much more than 400V at point B and probably a bit less, as a SWAG I would figure on B+ at point A in the 425V - 440V range or so..
You don't need to use a center tapped power transformer for this application, but you do need one with a seperate bias winding if you go this route. Alternatively you could possibly go with something commonly available like a 600 - 650VCT transformer (Hammond?) using full wave center tap rectification (Use UF4007 in series for reliability) with a 50V bias tap. I only suggest this if you cannot find better information than this. That VCT number also depends a lot on the dcr of the choke you will be using, and might need to be adjusted upwards to compensate for DCR. Umm, current rating should be something like 300mA.
The fact that the amplifier has a UL connected output and the nature of the tone control design suggests to me that this amplifier is oriented more towards a clean sound than anything else. Perhaps a hifi type output transformer would not too far off the mark given the nature of the rest of the design and comments about its sound online. Seems like this might be a good amplifier for use with acoustic guitars as well.
I was forwarded to a site by someone off Plexi palace.http://users.telenet.be/orangefg/orange_diy.htm
I has all the info I would need including the primary impedance of the output 1700½ for 4 el34's
and it tells about the power transformer too, so I guess I hit the jack pot so to say LOL.
Nick
I has all the info I would need including the primary impedance of the output 1700½ for 4 el34's
and it tells about the power transformer too, so I guess I hit the jack pot so to say LOL.
Nick
Fender experimented with UL circuits back in the late 1970's in the Ultra Linear Twin Reverb, the Bassman 135 and others. I think this was not all that sucessful. I owned a Bassman 135 and it was a horrible sounding amp for bass or guitar. The 100 watt Bassman or Super Bassman sounded much better. With that said it is certainly worth experimenting with because beauty is in the eye of the beholder and that's certainly true with guitar amps and guitar amp tone. You could even try making one side UL and the other a normal connection, why not?
I think that Fender went with these circuits so that they could eliminate the choke and also get a little bit more power out of 4 output tubes.
I think that Fender went with these circuits so that they could eliminate the choke and also get a little bit more power out of 4 output tubes.
I think even though the circuit I am going to use is a ul output stage I don't think I am going to use it. I'm going to do some modifications on it.
I know this will change the sound drastically but I don't think that will be entirely a bad thing.
I think I will put a transformer in it as a phase inverter and also use cathode bias if I can get away with it.
I'm not sure if I like the fac controller either, I know it just a variable lp filter but I don't see any use for it. That being said I still might try it. Also I think the adding of a master volume would be a good thing too.
I might even consider a switch to change from pentode to triode mode as a way to reduce the power output for playing that won't t off my wife LOL. Although she plays the drums so she could probably blow me away LOL.
Nick
I know this will change the sound drastically but I don't think that will be entirely a bad thing.
I think I will put a transformer in it as a phase inverter and also use cathode bias if I can get away with it.
I'm not sure if I like the fac controller either, I know it just a variable lp filter but I don't see any use for it. That being said I still might try it. Also I think the adding of a master volume would be a good thing too.
I might even consider a switch to change from pentode to triode mode as a way to reduce the power output for playing that won't t off my wife LOL. Although she plays the drums so she could probably blow me away LOL.
Nick
I have a GRO 100 in the shop right now. I basically reworked a butcher job. The output stage is NOT Ultralinear in this one, but the OPT had been rewound, so who knows. I used the same schematic you posted and that was the only difference(mistake?) I saw. I do have one piece of advice though, install a standby switch and use it. All of the non-stacked electrolytics WILL be overvoltaged until the tubes warm up. Also the first single capacitor(B) should be a 500 volter especially if you run the voltages that are present in the original GRO, I used a 450 volt there at first. When it was up and running the voltage was over 450. This is the first GRO-100 I've seen, serviced many of the others. In fact did many for the Blue Man Group, they love their Oranges. If you need transformers check out Mercury Magnetics, they have both the power and output. Yes they are a tad on the pricey side but they ARE clones of the originals so they sound like they are supposed to. They made all of the transformers for Orange a couple of years ago until Orange went Chinese. If you have any other questions ask away while I have it.
Craig
Craig
No problem just trying to get an idea of the power output of the trans. I trying to figure out if a power transformer I have on hand will work for this amp. It's from a hammond extension cabinet. It ran 3 el84 push pul amps. It's a rather large transformer It looks like it would have no problem producing 400 to 500 watts without breaking a sweat.
Nick
Nick
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