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Re: Bogen / NTS-1125 look like a 50-60 Watter...

Hey, Thanx very much for your addition. I gathered already you're an interstage devotee; how did I guess. ;) Personally I'm a total neophite, but I'll be learning.

I looked at some Bogen circuits but didn't find a 807 based one before. I did find one from those models discussed on DIYAudio with an 807, thanx. I'll look for more tomorrow.

I'm pretty sure I'll be ok with the OPT. The person I bought it from has been using it in his HT system. That's right, I just checked the eBay listing and it read "These NTS-1125 have two 16 ohm taps, 140v tap. both 16 ohm taps are strapped for 8 ohm speakers as wired now".

Thanx for the notes about the capacitance. I'll have to do that. I do think this amp will more likely be the one used driving the 4 ohm bass horn then the Dukane; though I will up-size the supply caps in those too eventually. I'm really going to need a 3rd of both this Bogen and the Dukane! ;) I'm definintely not planning on changing from the 807; it's what intrigued me in the 1st place.

And finally if you'll indulge me, I have a few questions that will illustrate just what a neophite I am with 'older' (ok, or 'real old') tube gear.

1) Is setting the bias higher as you mention making it operate furter in AB2 towards class B operation, or moving it more towards AB1?
2) If I don't have a service manual, is whatever pot I need to adjust to set bias 'intuitive' usually? And how do I know what value is 'right'?
3) When do I need to start old amps with a Variac? Only if they haven't been used for a long long time? Both these Bogens and Dukanes have been used (I think regularly) by the people I bought them from, so I think I don't need to start them with a Variac, but I'm wondering.

BTW, feel free to ignore these questions if answering them would be too major a task; I bet it is. I undertstand. I should buy some old service oriented books. I purchased 3 books on tube gear written before the 50s a few months back, but they are more theory then service.

Thanx much for your thoughts,
Steve


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