Bottlehead Forum

General Category => General Discussion => Topic started by: Thoburn on February 23, 2015, 04:34:18 AM

Title: Dynamite ST-70
Post by: Thoburn on February 23, 2015, 04:34:18 AM

Anybody have experience with the Dynakit ST-70 kit. I have found a replacement for the 7199 tube. I need something with more umph that a 300B amp. I built a Frugelhorn MK3 with an Alpair driver that is only 85 Db rated and my Stereomour doesn't driver them well. This for a secondary system for down stairs and the room is large.

Title: Re: Dynamite ST-70
Post by: Grainger49 on February 23, 2015, 04:43:46 AM

I still have one.  It did well with lower sensitivity speakers where my Paramours didn't.

What seems odd to me is horns and lower sensitivity.  That one is a head scratcher.

Title: Re: Dynamite ST-70
Post by: Zimmer64 on February 23, 2015, 07:34:48 AM

Can't help with the Dynakit, but I have built the VTA St-70 (tubes4hifi.com), which I use in my main system. The kit is great and so is the sound. There also is a support forum: http://dynacotubeaudio.forumotion.com

Michael

Title: Re: Dynamite ST-70
Post by: corndog71 on February 23, 2015, 11:51:23 AM

I second VTA!  They also sell a 60 watt stereo version called the ST120.  It's a great amp and can be made even better with some tweaking.  ;)

Title: Re: Dynamite ST-70
Post by: Thoburn on February 23, 2015, 05:04:50 PM

Thanks guys for the input. The ST-120 is a little to expensive for this project. I'll start stashing away some of the beer money and get an ST-70 kit. Much appreciated.

Title: Re: Dynamite ST-70
Post by: Thoburn on February 24, 2015, 05:02:14 PM

Quote from: Thoburn on February 23, 2015, 04:34:18 AM

Anybody have experience with the Dynakit ST-70 kit. I have found a replacement for the 7199 tube. I need something with more umph that a 300B amp. I built a Frugelhorn MK3 with an Alpair driver that is only 85 Db rated and my Stereomour doesn't driver them well. This for a secondary system for down stairs and the room is large.

Ok. The Alpair 7.3 have some hours on them now and I have to modify my first impression. At low to moderate listening levels with singer song writer music (Diana Krall, Nora Jones, Melody Gardot) they sound great with my Stereomour. Just don't try Beethoven's Ninth. I did. Maybe with a few hundred hours on them I'll try it again.

These Frugelhorn Mk3 with the Alpair 7.3 are an amazing speaker even though they are only 85 Db.

Title: Re: Dynamite ST-70
Post by: Paul Birkeland on February 25, 2015, 03:47:05 AM

I'll offer a little tidbit of thought on this matter. 

The maximum excursion on that particular driver is 4mm one way (noted for bass peaks, not sustained input), this would be 1 Watt of power at 55Hz.  Loading may or may not buy you a little more power handling.  At 75Hz, you can take more like 4W.

I'd still try a bigger push-pull amp, just for a point of comparison. 

-PB