Dirty Ol' Bogen

jpciii

I like pizza
I just came back from my non-audio buddy's house. He dug this DB115 out of his basement and sent me home with it. Now, what the heck am I supposed to do with it? I have no experience with tubes and I have never worked on gear before. Is it safe to plug it in?
 
wait 'til summa the tubesters around here start talking to you about that unit, but, in the meantime DON'T PLUG IT IN!! unless you have a variac and know how to bring it up ssslllloooowww .... but in the meantime, look for deteriorated insulation on wiring and get all that dust offa there...

shrinkboy
 
Read the stickey at the top of the page and it has a fairly detailed explaination on how to bring an old amp back to life.
What you have is a nice mono block of around 15 watts hence the 15. That gold was only painted on their made for audio stuff so it is not a PA amp but made for in home Hi Fi.
The chances of that Bogen being ready to go after just a session with a variac are pretty slim, but the only way to find that out is to warm it up and try it out.
 
I may be a risk taker but I always just hit it with the 110 AC, just as long as it has a fuse. Only time I had damage out of hundreds of tube units I've tried was with a 1930 Sparton radio, a resistor was accidentaly disconnected and the electrolytics began to smoke.

Before I really put a device into use, though, I replace all the paper caps, add a fuse if it doesn't have it, and check all wiring for deterioration. jpciii, I would recommend that you learn about repair and maintenance of these amps and the proper safety precautions before you really begin using it, even if it passes the "smoke test".
 
Chaud,
This guy has never had a piece of tube gear before. The easiest, safest thing to do is to clean, inspect and warm the thing up using standard precautions. The reason they are commonly used by people that know something about tube gear is that they tend to work. A used Variac is cheaper than a set of caps and warming a piece of gear up is a whole lot easier than recapping one.


jpciii,
Can you read a schematic? The Sam's number for the service guide is 376-10.
Also do you want a mono integrated amp? If not you will have to find another one just like it for stereo and since I don't know what kind of gear you have, maybe speakers that will work with a 15 watt 6BQ5 PP amp. Make no mistake David Bogen was one of the largest producers of tube amps in the world and the DB series was HiFi and the gold painted DF series the TOTL. That doesn't mean that what you have is worth a lot, but when it was new it was as good as anything out there using those tubes. Figure the age to be around 40 to 45 years.
 
jpciii:

Do the following - a quick and safe way to power up an old unit.

Get a basement ceiling lamp (light socket) fixture (the one that mounts directly to an electrical box) and a good extension cord,

Carefully cut into the extension cord about 2 feet from the socket end (nearest the unit) and separate the wires.

Cut the black wire. Strip the ends and connect these to the screw terminals under the light socket. Screw the lamp fixture down onto a piece of suitable wood (protects against touching the bare connections :D ).

Put a 100 or 150 watt bulb into the lamp socket.

Plug the unit into the extension cord and the extension cord into the wall.

Turn on the unit.

The bulb will reduce the draw to the unit by at least 50%. You can substitute 60 watt or 40 watt bulbs for an even greater draw.

Paul
 
Yes, the light bulb method is easy and effective, but read to sticky at the top of the page anyway. There is more to it, like not having the power tubes in during the 1st stages so that the electrolitics reform fully and correctly before full power is applied.
I would advice your finding a local who works on antique radios. They have the same gear and do the same things to their finds.
 
Thanks for the replies, guys. Very helpful

Thatch:

I read the sticky. Will read it again later to make sure I didn't miss important stuff.
I actually have speakers that will like this amp. Homemade cabs (pretty nice actually) with 15 inch Jensen Dualax (whizzer cone) two way speakes (16 Ohm). The cabs are a kit, I think, that has a cut-out for a big horn for the upper freq. No horns or crossover though, just the 15 inchers. I used them with an old Marantz and they seem very efficient.
Now, do I want a mono setup? Probably not at this point. I'm just starting to build my first real audio setup around a Marantz 2265B. This Bogen will either be an amusing little learning project or something to trade/sell towards speakers or a tape deck.
I've never read a schematic, but I am certainly smart enough to learn. I also have poor noobie soldering skills.

I took off the bottom and took a pic. I noticed a couple of wax drops and some spots that look like they got pretty hot at some point. Maybe this is normal... see pic. Didn't notice any oil or frayed wires, just lots of dust bunnies.

thanks
 
Looks to be in good shape. Yes there are a few things I would change if I was going to keep it, but I would clean it, get some DeOxit after the pots and switches, test the tubes and warm it up. The full range Jensens sound like a good bet. Its too bad your not in this neighborhood. We could get a Sam's at the library, test the tubes and replace the bad ones at Nortex and pik up a cheap variac there as well as replacement caps and resisters.
Your hot spots are from high wattage wire wound resisters which get hot. The wax off the wax covered paper caps is normal and the only thing I would think of changing before cleanup and warmup are the 3 small electrolitic caps under the hood. They have the cardboard covers and the + sign on them. Not changing then right out probably isn't a big deal but they would be weak spots. I'll have to take another look for a selenium rectifier.
 
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Vinyl Hanger is talking about rebuilding his DB10 which is probably simular to yours but with older style tubes. He loves his. I have a pair of the DB20 DFs which are great amps. I think your amp is one of the earlier examples of HiFi made with EL-84(6BQ5) made in the US. The Eico HF-12 was a 6BQ5 PP kit but this amp is better. You can tell by the size of the transformers for one.
Before you HF-12 owners start yelling I own 3.
 
I cleaned it. I'm gonna look into finding someone local who can put it on a variac. I heard there was a guy in town who is a vintage guitar amp repair tech. Sound ok?
 
hmmm... Nobody in town will even look at it for less than $45. :( I'm just a poor college student, and I can think of many better ways to spend $45... like buying a variac, some caps and maybe a tube tester LOL!
 
Excellent cleanup job. That looks better than 90% of the vintage gear I see and 100% of the gear I own. I have a Bogen PP 6BQ5 mono receiver around here somewhere and a SE 6BQ5 stereo receiver underfoot in the shop. I like the look of them. Before I gave anyone more than $30 to fix it I'd wait for a used Variac to come along. I have 4 and have never paid more than $35 for one. The parts you'd need to fix this, barring blown transformers, would cost pocket change. You could re-do every passive component in the thing except PSU caps for $10, but you probably wouldn't have to. I agree about canning the wax/paper capacitors. Put in mylars and rest easy about those.
I knew a guy who made his own variable line voltage rig from 10 surplus 12.6VAC 2A filament transformers screwed to a board. He paraleled the primaries, seriesed the secondaries and tapped off the secondary voltages with a 12-position rotary switch. It was clumsy but it worked for gear running up to 250va of power consumption and it cost him next to nothing. If you were to buy those filament transformers new from Hammond, a variac would definitely be cheaper. Sometimes you find surplus filament transformers from tube testers with taps from 1.5VAC to 117VAC, but I don't know if the secondary current is sufficient.
 
I bet if you first clean all the control and tube sockets and pins confirm all the tube are good. Then bring it up extremely slow on a variac the amp works fairly well. If you do this do yourself and the amp a favor and don't leave it on when your not there to shut it off if it decides to go south.
I have brought up hundreds of amps on a variac that have sat idle for years. It never ceases to amaze me that they still work. I alway test every tube first though. A good portion of these amps were shelved for no more then a bad tube.

Craig
 
Beautiful cleanup job. And yep, I love my little DB. Simple simplicity at its best. I hope you get it going. Finding a single speak is getting easier at the thrifts all the time. And the right amp and speaker combination is nice to set in a corner of a den to play sweet old tunes like they were meant to be played.
Thatch, is it odd that this amp doesn't switch to 4 ohm loads, or is that normal?
 
Tubes like higher impedence and some amps even had 32 ohm taps. Eico AF-4 for one.
I am not sure about this but I think that there are less windings needed for 4 ohm and the more windings the better. I could be way off on that but I have been told that if you don't need the power that you can get better sound off of a higher impedence tap.
That amp is looking great! What a nice find.
 
Originally posted by NOSValves
I bet if you first clean all the control and tube sockets and pins confirm all the tube are good. Then bring it up extremely slow on a variac the amp works fairly well. If you do this do yourself and the amp a favor and don't leave it on when your not there to shut it off if it decides to go south.
I have brought up hundreds of amps on a variac that have sat idle for years. It never ceases to amaze me that they still work. I alway test every tube first though. A good portion of these amps were shelved for no more then a bad tube.

Craig

Craig makes a good point. The majority of vintage amps that I find in unrestored condition have one disabling fault. Think about it. People tend to use something until it doesn't work anymore, then put it up to be fixed later, or replaced. That's the condition you find them in years later. Often it's a tube, less often a cap or resistor.
 
Hey guys, thanks for the encouraging words. First I used a paint brush and a toothbrush with a vacume to suck up the loose dirt. Then I sprayed some rags with a little Windex and wiped away. I accidently brushed up against one of the Westinghouse tubes with a rag, and the yellow paint came right off. I took the tubes out after that. The pins appeared to be pretty clean. There where 4 Westinghouse ones that looked somewhat new, and 2 Mullard tubes that looked a little older. The faceplate and the knobs cleaned up nicely too. I used warm water, a little detergent, and the same toothbrush. The knobs took some work though, they where really crusty.

There are a lot of little antique shops, second-hand shops, and flea market type places around here. I should be able to find a variac and a tube tester if I look around. Even the pawn shops have a bunch of old tools and things. ( I wish these places had some audio gear, but I haven't come across anything good yet ) I'll make the rounds in the next few days, and post some more questions when I'm ready to dig into it.

thanks again
:nerd:
 
Ask around in TV repair shops that look like they have been there a long time. I picked up a variac, a tube tester(didn't work) and a few hundred tubes for $20 doing that once. A lot of TV tubes are no good for audio but some are. And since there are TV forums here you can pass on any tubes that don't have audio applications. Maybe do a little horse trading.
 
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