Hoffman Amplifiers Tube Amplifier Forum

Other Stuff => Other Topics => Topic started by: MoparWade on February 03, 2017, 08:08:47 pm

Title: 300B SE Stereo
Post by: MoparWade on February 03, 2017, 08:08:47 pm

Want to build a home stereo with 300B's. Found this circuit and wondered what peoples thoughts were on it. I would clearly have to use this circuit twice for left and right channels. Thinking I would run a shared PT but from there on everything would be doubled. Let me know what you think.

Title: Re: 300B SE Stereo
Post by: shooter on February 03, 2017, 08:30:34 pm

Here's my MonoBlock version with a KT88.
I also basically copied the pre-section you're showing to drive a QuadSE of EL84's.

The QuadSE drove a pair of Audio Nirvana 8" and sounded very sweet, probably wouldn't pass a cork-sniffer, but most discerning folk gave me a thumbs up.  Dialing the KT88 now for about the same, speakers still to be chosen.

Title: Re: 300B SE Stereo
Post by: MoparWade on February 03, 2017, 08:40:24 pm

I think you posted some pics of that build a while back?

Title: Re: 300B SE Stereo
Post by: PRR on February 03, 2017, 09:31:42 pm

> thoughts

Only 70V across driver plate resistor. Can't swing 60V peak, and will be straining to get near there.

Meanwhile the 300B is run at very high voltage, will need large drive voltage, probably over 80V peak.

diyaudio.com will have far more thoughts. (Far too many.....)

Title: Re: 300B SE Stereo
Post by: MoparWade on February 04, 2017, 01:33:30 am

Thanks for the response. It's a bit of a gear shift from guitar amp to hi-fi but I'll figure it out.

Title: Re: 300B SE Stereo
Post by: shooter on February 04, 2017, 08:38:40 am

Quote

It's a bit of a gear shift

Yup, you get to put her in drive and just enjoy the ride, instead of 2nd gear with the tach red-lined :icon_biggrin:

300B was a pricey tube last time I looked, depending on your volume hopes, a big bottle guitar tube either UL or triode strapped might be a choice.

This is my 3rd official audio build, big quality iron for OT, and caps that let all the tones through is a recommendation.  High quality speaker is a must also.  If you get "tempted" to plug in a guitar, expect very sterile clean.