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 Post subject: Re: Bogen DB-130 amp 'restoration'...
PostPosted: Feb Mon 12, 2018 6:43 am 
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Location: Thornhill, Ontario
BikenSwim wrote:
... 5AR4 is like a damper tube, must use a smaller input filter capacitor to avoid flashover as it has a much lower internal resistance and voltage drop than a 5U4GB... Don
Now that is a very good point! I knew they dropped less voltage, also the plate to cathode distance does look closer, but I had not linked that to its needing a smaller input cap. Thanks.
Cheers,
Roger

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Ontario Vintage Radio Assoc. http://www.ovra.ca


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 Post subject: Re: Bogen DB-130 amp 'restoration'...
PostPosted: Mar Fri 02, 2018 4:28 am 
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Joined: Feb Sun 04, 2018 9:15 pm
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I am looking for those space age optional feet that go under those gold Bogen chassis. Need two sets if anyone has some for sale. Thanks!


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 Post subject: Re: Bogen DB-130 amp 'restoration'...
PostPosted: Mar Fri 02, 2018 6:31 pm 
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Steven C wrote:
I am looking for those space age optional feet that go under those gold Bogen chassis. Need two sets if anyone has some for sale. Thanks!

Those and the right size case can be hard to find. They come up occasionally on ebay. Probably best to watch for a junker to take parts off of. That's what I do.

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 Post subject: Re: Bogen DB-130 amp 'restoration'...
PostPosted: Sep Thu 20, 2018 12:37 am 
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Help please...any Bogen DB130 owners want to share how they connect a stereo turntable to the preamp section. I have a summing box and use AUX 2 as a mono channel input. Can I use the phono input..either one, with a modern Audio Technica turntable? The gain on the turntable is much lower then the CD player hooked thru the same box. I need more preamp for the phono cartridge. Any help appreciated!


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 Post subject: Re: Bogen DB-130 amp 'restoration'...
PostPosted: Sep Thu 20, 2018 2:37 pm 
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There are two methods that should work.

1) you could try strapping a stereo cartridge for mono and then connecting that to the MAG PHONO in on your db-130.
http://forums.stevehoffman.tv/threads/stereo-cartridge-mono-wiring.181411/

2) You could purchase a separate stereo phono preamp and then connect it to your summing box and AUX input.
https://www.amazon.com/gp/product/B01J3CQKFO/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1

Also, a passive summing box need be no big deal:
http://www.rane.com/pdf/ranenotes/Why_Not_Wye.pdf

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 Post subject: Re: Bogen DB-130 amp 'restoration'...
PostPosted: Sep Thu 20, 2018 3:33 pm 
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Joined: Feb Sun 04, 2018 9:15 pm
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I have a new AT turntable with a new stereo cartridge run thru summing box...can I use either phono input (mag low or mag hi) on the old amp? Currently using an aux input but have to turn up the volume to attain the same volume as my CD player hooked to the exact same aux input. Searching for an owner's manua for the Bogenl...hope to find one. Thanks!


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 Post subject: Re: Bogen DB-130 amp 'restoration'...
PostPosted: Sep Thu 20, 2018 3:36 pm 
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Sorry Sol...you suggested swapping my new cartridge for an older mono magnetic cartridge then using the phono input...got it!


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 Post subject: Re: Bogen DB-130 amp 'restoration'...
PostPosted: Sep Thu 20, 2018 3:56 pm 
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Steven C wrote:
Sorry Sol...you suggested swapping my new cartridge for an older mono magnetic cartridge then using the phono input...got it!

I'm sorry, but an older mono cartridge will not work. The reason is because you cannot play modern stereo LPs using an old mono cartridge - it will ruin your records. You could only play old mono records using an old mono cartridge. You can buy modern mono cartridges that will also work with your stereo records, but that would potentially be a lot of expense, and you do have some inexpensive alternatives.

If you read the link, it explains how to convert a modern stereo cartridge for a mono input. You could also make a connector box to plug your turntable output into that ties the L and R together, then connect that to your MAG LOW input.

I have a manual somewhere, I will see if I can post a picture of the relevant part, however for your situation it won't be much help because it assumes you are using a mono cartridge.

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 Post subject: Re: Bogen DB-130 amp 'restoration'...
PostPosted: Sep Thu 20, 2018 11:57 pm 
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Hi Sol...found a manual thru here and ordered it...tried connecting the summing box from the turntable on both low and hi phono input (one at a time of course), and gently brought up the volume control...extreme preamp on both...my JBL C36 cabinet was thumping hard enough to make me worried at less than 1/4 volume. It was going to clip at that level. I guess I'll wait to get my owner's manual...and follow your links this time. Thank you for being patient...new at tubes


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 Post subject: Re: Bogen DB-130 amp 'restoration'...
PostPosted: Sep Fri 21, 2018 1:09 am 
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If the summing box is active then that could cause the issue.

If it is passive then it should work fine.

That said all you need is an RCA Y cable with two RCA jacks and one RCA plug to make the record player mono.


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 Post subject: Re: Bogen DB-130 amp 'restoration'...
PostPosted: Sep Fri 21, 2018 2:19 am 
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I was told the y plug would not deliver proper input to the preamp section but maybe I'm just gullible. Anyway...the newer turntable has a built in preamp that's switchable...problem solved :) I will keep using the aux input with preamp on


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 Post subject: Re: Bogen DB-130 amp 'restoration'...
PostPosted: Sep Fri 21, 2018 1:39 pm 
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Location: Warner Robins, GA
Awesome.

The Y cable just shorts the positives of the cartridge together in the same way as you would at the cartridge itself.


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