|
Title: Not a lot of people building these?? Post by: Franc on April 17, 2010, 06:53:32 AM HI,
I am about to build a DR103 clone. Going by pics and layout of the original but using some of Nik's parts. First thing that catched my attention is the heatersupply. Why is Nik adding 100R resistors to ground (normally used with a tranny without center tap) while the tranny cleaarly has a center tap? Just wondering :) Title: Re: Not a lot of people building these?? Post by: tmac on April 23, 2010, 07:45:30 AM From the Ceriatone layout image it seems to have seperate heater secondaries for preamp and poweramp, and only the poweramp one has a centre tap? Maybe this could reduce preamp hum?
I have a pre-built DR103, but haven't inspected the heater circuit. I might do it just to see if it really has dual heater secondaries. Good luck with your build! Title: Re: Not a lot of people building these?? Post by: Franc on April 23, 2010, 07:59:51 AM Ah! Good catch. Hadn't noticed the fact that there's 2 heatercircuits.
That explains it :) Title: Re: Not a lot of people building these?? Post by: JimmyPage968 on January 17, 2011, 05:16:53 PM HI, I am about to build a DR103 clone. Going by pics and layout of the original but using some of Nik's parts. First thing that catched my attention is the heatersupply. Why is Nik adding 100R resistors to ground (normally used with a tranny without center tap) while the tranny cleaarly has a center tap? Just wondering :) I would definitely love to see pictures of yours. Title: Re: Not a lot of people building these?? Post by: plasticvonaband on July 14, 2011, 09:46:36 PM if i'm looking at the layout properly, there is only one set of filament secondarys, center tapped as per normal, and one set of HT (High voltage) secondary taps center tapped as per usual. I attached an image to better explain...
Title: Re: Not a lot of people building these?? Post by: tmac on July 15, 2011, 09:29:34 AM But your picture doesn't seem to be the same as the one on the Ceriatone site:
http://www.ceriatone.com/images/layoutPic/HeyWhat/HeyWhat103.jpg (http://www.ceriatone.com/images/layoutPic/HeyWhat/HeyWhat103.jpg) Title: Re: Not a lot of people building these?? Post by: wyatt on July 15, 2011, 01:23:20 PM I think tmac nailed it. There is no center tap on the preamp heater currents.
You may occasionally find a center-tapped filament current that also uses the 100 ohm resistors, that's for noise, the 100 ohm resister faux center tap actually gives a better reference to ground than a center tap. How much better? How much less noise? Probably not much, must people just use a center tap, but if I were building a hi-gain amp, I might consider it. Title: Re: Not a lot of people building these?? Post by: cmoore on July 15, 2011, 01:36:38 PM Common practice to use the 100 ohm resistors with a PT Heater CT......been done for years.
Perhaps you guys are discussing 2 different layouts....? 504 has a single 6V winding 103 has a PT with 2x6V winding......perhaps.? Best Title: Re: Not a lot of people building these?? Post by: plasticvonaband on July 15, 2011, 06:08:15 PM yup. I was looking at the 504 layout. Doh! My bad guys ;)
|