Bogen X120B/X220B
Moderators: pompeiisneaks, Colossal
Bogen X120B/X220B
Thrift store find for $15. No idea if anything works. Aside from dust it is reasonably clean, and I've got to remove the huge sticker label they put on it ;-{ informing me of the price. Includes Mullard ECC83 and Mullard 6C4 rectifier. GE power tube 6W6 GT. If the OT is compatible, this looks like a nice champ-like conversion. Any ideal where I might get a schematic? I was hoping for OT and PT information, but it wouldn't be the first time I had to solve for what it is.This was some sort of PA system, so not optimistic on the OT, but the diagram on the bottom says there are two OT's, go figure. Happy find. Tubes alone, if they have life left are worth what I paid!
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Stevem
- Posts: 5144
- Joined: Fri Jan 24, 2014 3:01 pm
- Location: 1/3rd the way out one of the arms of the Milkyway.
Re: Bogen X120B/X220B
It's such a simple circuit do ya really need a schematic?
You can guess real close at the Main V+ voltage by knocking off 20 to 25 volts from what the first filter is rated at,and from there and by means of the tubes spec's and the power supply dropping resistor values use good old ohms law to figure out the other up stream power supply voltages!
Try Sams photo-facts for a schematic.
To remove stickers I use a blow dryer set to medium hot to soften it up well then they peel right off if they are not 20 years or more old.
You can guess real close at the Main V+ voltage by knocking off 20 to 25 volts from what the first filter is rated at,and from there and by means of the tubes spec's and the power supply dropping resistor values use good old ohms law to figure out the other up stream power supply voltages!
Try Sams photo-facts for a schematic.
To remove stickers I use a blow dryer set to medium hot to soften it up well then they peel right off if they are not 20 years or more old.
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Re: Bogen X120B/X220B
I can figure out the PT and OT. The whole thing is in original form, so there is more than enough there to give me a very good idea. Unfortunately, I can't fire it up because 1) I'm sure it needs a cap job without even looking, and 2) I don't know what the appropriate load is the for the OT, thought at 4W, I guess I could use just about any load and it would be OK. I'm not interested in the rest. I was hoping to find a schematic that reveals the transformer specs! Sometimes the public library will get Sams for me. I'll try them. Otherwise, I'll have to test the OT for turns ratio. I am feeling lazy and was hoping for a shortcut.
Thanks for the hairdryer trick. Unfortunately, I already f'd up by pulling off some of the label and now there is the "paper under label" left to deal with. I'll give the hair dryer trick a try. I think it should work. If not, I can resort to a solvent to dissolve the glue, but I don't like the smelly stuff indoors.
Thanks for the hairdryer trick. Unfortunately, I already f'd up by pulling off some of the label and now there is the "paper under label" left to deal with. I'll give the hair dryer trick a try. I think it should work. If not, I can resort to a solvent to dissolve the glue, but I don't like the smelly stuff indoors.
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Stevem
- Posts: 5144
- Joined: Fri Jan 24, 2014 3:01 pm
- Location: 1/3rd the way out one of the arms of the Milkyway.
Re: Bogen X120B/X220B
Sometimes power supply filters flat out surprise me !
Two days ago I was working on a 63 Ampeg with its original multi filter can . It had a bad diode in the bridge due to a shorted tube and I was sure the can would turn up bad also, but as it turned out the amp ( atleast for now) plays fine!
In short you might to might find that your Bogen's filters might turn up being ok at for a bit of moding and build time!
Two days ago I was working on a 63 Ampeg with its original multi filter can . It had a bad diode in the bridge due to a shorted tube and I was sure the can would turn up bad also, but as it turned out the amp ( atleast for now) plays fine!
In short you might to might find that your Bogen's filters might turn up being ok at for a bit of moding and build time!
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Re: Bogen X120B/X220B
Back at this thing. There were several things about the original build that bugged me and that I didn't like. For example, the heater wires were likely 22 ga. and the insulation was sticky-icky. In the end, without attempting to trace the circuit, I gutted it. I'd like to build a simple amp in it. The chassis is small. It will be a PTP build. I'm not too choosy when it comes to this sort of build. Anything that will sound good will float my boat. I'm looking to do it on the cheap, which means I'd rather do this with what I have on hand. Sorry in advance for a wordy post.
It came with two output transformers. One is a champ sized single ended, turns ratio 8.3:1. The internal speaker meters around 42Ω. Assuming that DCR is 75-80% of impedance, that put it at 52-55Ω. Backsolving for the primary suggests about 3.7K. This doesn't seem to make sense for a 6W6GT power tube. It is what it is. The speaker is a 4" Jensen. The amp dates to 1963 by the pots and transformer codes. Though tempted to use it, I think I will putting the speaker and OT on eBay unless someone here can convince me there is a better use for it.
The other OT is a hefty (for it's size) cylinder. It measures about 1.5" diameter x 2" high and weighs 7.2 oz. (38mm x 50mm. 0.2kg.). It has 6 wires coming out of the bottom. The white has no continuity with the others, so I'm assuming it is a frame ground. The black-green appears to be the primary. What seems odd is the 3 wires that make up the secondary, blue-red-brown. Blue-red and brown-red appear to be the same DCR and have the same Vout on the low voltage test. Input 7.28vac to blue-brown gives 174.1v out on black-green and half that to the red, which I'm certain is a CT. So, the turns ratio is 23.9:1. I'm liking this for a build, figuring it will work at roughly 5KΩ to 8Ω or 10KΩto 16Ω. I'm confused by the secondary being split 50/50, each half being roughly 12:1. I don't know what I'd do with 12:1, so I'm inclined to just put some heat shrink on it and ignore it. Any thoughts on this would be appreciated. In particular, do you think this logic holds water?
Thanks.
It came with two output transformers. One is a champ sized single ended, turns ratio 8.3:1. The internal speaker meters around 42Ω. Assuming that DCR is 75-80% of impedance, that put it at 52-55Ω. Backsolving for the primary suggests about 3.7K. This doesn't seem to make sense for a 6W6GT power tube. It is what it is. The speaker is a 4" Jensen. The amp dates to 1963 by the pots and transformer codes. Though tempted to use it, I think I will putting the speaker and OT on eBay unless someone here can convince me there is a better use for it.
The other OT is a hefty (for it's size) cylinder. It measures about 1.5" diameter x 2" high and weighs 7.2 oz. (38mm x 50mm. 0.2kg.). It has 6 wires coming out of the bottom. The white has no continuity with the others, so I'm assuming it is a frame ground. The black-green appears to be the primary. What seems odd is the 3 wires that make up the secondary, blue-red-brown. Blue-red and brown-red appear to be the same DCR and have the same Vout on the low voltage test. Input 7.28vac to blue-brown gives 174.1v out on black-green and half that to the red, which I'm certain is a CT. So, the turns ratio is 23.9:1. I'm liking this for a build, figuring it will work at roughly 5KΩ to 8Ω or 10KΩto 16Ω. I'm confused by the secondary being split 50/50, each half being roughly 12:1. I don't know what I'd do with 12:1, so I'm inclined to just put some heat shrink on it and ignore it. Any thoughts on this would be appreciated. In particular, do you think this logic holds water?
Thanks.