Extra overdrive stage in ODS?
Moderators: pompeiisneaks, Colossal
Re: Extra overdrive stage in ODS?
My D'Lite 44 is pretty gainy, just sayin'.
Re: Extra overdrive stage in ODS?
Hi ryan,
I would caution building the Bogner circuit as shown. Even though I have not built this particular circuit, I have built many high gain stages. This scheme does not have enough control over the interstage attenuation, ie pots. The third and fourth stages will be railed resulting in a sticky or farty sound. Compare this scheme to the Dumble, and you will notice more interstage attenuation pots on the Dumble. BTW, the Bogner scheme as shown would probably overdrive the PI too, even with the tone stack after the cathode follower.
If you build the circuit, change a couple of the 500 k resistors to ground with 500 k pots feeding the next stage grid. This should help.
To answer your question, and as others stated, this is a complete standalone OD stage. The wiper from the treble pot would feed the power amp.
Good luck,
John
I would caution building the Bogner circuit as shown. Even though I have not built this particular circuit, I have built many high gain stages. This scheme does not have enough control over the interstage attenuation, ie pots. The third and fourth stages will be railed resulting in a sticky or farty sound. Compare this scheme to the Dumble, and you will notice more interstage attenuation pots on the Dumble. BTW, the Bogner scheme as shown would probably overdrive the PI too, even with the tone stack after the cathode follower.
If you build the circuit, change a couple of the 500 k resistors to ground with 500 k pots feeding the next stage grid. This should help.
To answer your question, and as others stated, this is a complete standalone OD stage. The wiper from the treble pot would feed the power amp.
Good luck,
John
Re: Extra overdrive stage in ODS?
Hi Guys,
The Bogner's interstage attenuators chop the signal in half , twice. That should be more than enough to keep the signal from "railing" the third and fourth stage. One of the main reasons to chop the signal down is to prevent grid rectification, the main culprit of a sticky or farty sound, or to prevent clipping the plate. If you replace just the lower leg of the attenuator with a 500k pot, in every setting other than 500k you will be decreasing the attenuation thus increasing the chances of grid rectification. If you replaced the entire attenuator with a pot (a.k.a volume control) than this would give control between each gain stage just like with a Dumble.
I have played an Ecstasy and thought that it sounded very good so I can only assume that the interstage attenuator is designed empirically with the goal of having a nice (subjective) distortion, meaning not farty or sticky. Most amps out there that do not have an adjustable attenuator between each stage ala Dumble and, IMHO, a lot of them sound very good (subjective).
Basically, my point is that if the amp is properly designed it should sound good. It doesn't have to have user control over every gain stage to achieve this as most don't. And sometimes it is tough to tell how a circuit performs just by seeing it on paper. Throw one more 500k/ 500k attenuator in there and this is a clean preamp with no worrys about a flatulant sound. Just MHO.
P.S.- The Ecstasy has a master volume which solves the problem of overdriving the PI or PA if thats not what you are after.
-Kevin
The Bogner's interstage attenuators chop the signal in half , twice. That should be more than enough to keep the signal from "railing" the third and fourth stage. One of the main reasons to chop the signal down is to prevent grid rectification, the main culprit of a sticky or farty sound, or to prevent clipping the plate. If you replace just the lower leg of the attenuator with a 500k pot, in every setting other than 500k you will be decreasing the attenuation thus increasing the chances of grid rectification. If you replaced the entire attenuator with a pot (a.k.a volume control) than this would give control between each gain stage just like with a Dumble.
I have played an Ecstasy and thought that it sounded very good so I can only assume that the interstage attenuator is designed empirically with the goal of having a nice (subjective) distortion, meaning not farty or sticky. Most amps out there that do not have an adjustable attenuator between each stage ala Dumble and, IMHO, a lot of them sound very good (subjective).
Basically, my point is that if the amp is properly designed it should sound good. It doesn't have to have user control over every gain stage to achieve this as most don't. And sometimes it is tough to tell how a circuit performs just by seeing it on paper. Throw one more 500k/ 500k attenuator in there and this is a clean preamp with no worrys about a flatulant sound. Just MHO.
P.S.- The Ecstasy has a master volume which solves the problem of overdriving the PI or PA if thats not what you are after.
-Kevin
Last edited by Tavda3172 on Wed Dec 12, 2007 5:31 pm, edited 1 time in total.
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Fischerman
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Re: Extra overdrive stage in ODS?
The clips I've heard of the Ecstasy sound anything but sticky and/or farty. They are quite smooth in fact. I've never played an Ecstasy however I have built that circuit before and it certainly can sound sticky/farty/fuzzy...but I built it a second time and it sounds great. Smooth, rich distortion.
IMO, the B+ voltages on that schemo seem low. I don't know what the voltages in a real Ecstasy are and I don't have my homebrew (the good sounding one) voltages handy but when I built it with those lowish B+ voltages it sounded bad but with higher supply voltages it sounds great.
I have another schemo that shows a slight difference from that one posted. The difference is the interstage attenuation 'network' between the second and third stages. The 'other' schemo I have shows the same coupling cap, then the series 470K, then the 470K//470p pair in series with the first 470K, then it splits to the grid and the 470K to ground. Other than that they are the same. Also, most of the 500K are shown as 499K (however...not all...which seems strange) but that seems trivial.
EDIT: the Bogner distorts in a similar way that the SLO, Dual Rectifier, and JCM800 (2203/2204) Marshalls. The bulk of the distortion occurs in that gain stage/cathode follower pair...which is a totally different tone than an ODS. And IMO when set-up right, these GS/CF pairs can distort beautifully.
Some light reading attached.
IMO, the B+ voltages on that schemo seem low. I don't know what the voltages in a real Ecstasy are and I don't have my homebrew (the good sounding one) voltages handy but when I built it with those lowish B+ voltages it sounded bad but with higher supply voltages it sounds great.
I have another schemo that shows a slight difference from that one posted. The difference is the interstage attenuation 'network' between the second and third stages. The 'other' schemo I have shows the same coupling cap, then the series 470K, then the 470K//470p pair in series with the first 470K, then it splits to the grid and the 470K to ground. Other than that they are the same. Also, most of the 500K are shown as 499K (however...not all...which seems strange) but that seems trivial.
EDIT: the Bogner distorts in a similar way that the SLO, Dual Rectifier, and JCM800 (2203/2204) Marshalls. The bulk of the distortion occurs in that gain stage/cathode follower pair...which is a totally different tone than an ODS. And IMO when set-up right, these GS/CF pairs can distort beautifully.
Some light reading attached.
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Re: Extra overdrive stage in ODS?
Kevin,
I don't doubt that a true bogner sounds good. I was just pointing out to the original poster some troubles he may encounter with the scheme posted. BTW throwing away half the signal twice as you pointed out, with the voltage divider, may not be enough as the gain stages are set up to have fairly decent gain, therefore even a 5 v p-p signal will try to swing 100+ volts etc.
Just trying to help a new guy out, high gain setups can be difficult to tune without a scope etc, and an interstage pot or two could help ease the pain.
FWIW, my poison is the bone crushing bottom end of the Egnaters..... As I have said before, I love heavy Marshall tones....
John
I don't doubt that a true bogner sounds good. I was just pointing out to the original poster some troubles he may encounter with the scheme posted. BTW throwing away half the signal twice as you pointed out, with the voltage divider, may not be enough as the gain stages are set up to have fairly decent gain, therefore even a 5 v p-p signal will try to swing 100+ volts etc.
Just trying to help a new guy out, high gain setups can be difficult to tune without a scope etc, and an interstage pot or two could help ease the pain.
FWIW, my poison is the bone crushing bottom end of the Egnaters..... As I have said before, I love heavy Marshall tones....
John
Re: Extra overdrive stage in ODS?
John,
Please don't take my above post the wrong way. I just want to make sure that all the "why's" for trying something or not are understood. About making the amp easier for a new guy, that makes total sense that it would be easier to tweak with a volume control between each stage. Please take the above post as my opinion or preference and please, please, continue to post yours. I feel that everyone here has something valuable to say and that is just my take on it. Your mileage may vary. Keep up the good work.
-Kevin
Please don't take my above post the wrong way. I just want to make sure that all the "why's" for trying something or not are understood. About making the amp easier for a new guy, that makes total sense that it would be easier to tweak with a volume control between each stage. Please take the above post as my opinion or preference and please, please, continue to post yours. I feel that everyone here has something valuable to say and that is just my take on it. Your mileage may vary. Keep up the good work.
-Kevin
Re: Extra overdrive stage in ODS?
Well thanks for the replies everybody. I had definately planned to put in a volume pot at the end. I will definately put some trim pots between gain stages as well, just to have the ability to adjust things.
Fisherman, do you have any idea about the ranges of those voltages? They seemed low to me, just by looking at other amps. I guess it isnt that hard to experiment with those. Thanks alot everyone!
Fisherman, do you have any idea about the ranges of those voltages? They seemed low to me, just by looking at other amps. I guess it isnt that hard to experiment with those. Thanks alot everyone!