amp-schematic questions...

macce78 · 25th November 2004, 07:50 PM

Hi!

I'm finally starting my first valve amp project, and as I Googled around for a nice and simple (read: cheap) SE-design I ran in to this:http://www.lundahl.se/claus_b_se.html. What do you guys think of this one, and is it a suitable project for a noob?

Is it OK to run the amp with a 230V // 280-0-280 0,190A / 6,3V 4A / 5V 2A transformer if I connect the 280 V windings in parallel? That's the closest match I can find here in Finland, and I don't have a credit card wich makes ordering from abroad a bit tricky... (it's actually quite hard to find the right parts to any design, and I'm pretty amazed that only the transformer is missing from this one.)

cheers,

Marcus

fdegrove · 26th November 2004, 12:32 AM

Hi,

That xformer should be O.K.
You could even arrive at the same voltage values if you could source a 10H 200mA choke with a DCR lower than 200 R.

It could be made as a first DIY amp I suppose but be aware of the high voltages involved.

Just one note: I wish Mr. Byrith would have picked a 6SL7 or 12AT7A (for instance) iso that dreaded 12AX7........
And another one: variable feedback often means that unless you have the necessary mearuring tools you'll never be sure when you have the correct setting.
That's enough to drive alot of people bananas...

Cheers,

macce78 · 28th November 2004, 07:22 PM

Do you think a 7 H 250 mA 60 ohm choke would do (Lundahl LL1673 / 7H) if I increase the value of the filter capasitors? That's the only choke I found that can handle 250 mA with current.

I calculated that using a 280 V xformer and this 7 H 60 ohm choke will give me about 5 Volts more compared to the original setup. This won't do any harm, will it?

fdegrove · 28th November 2004, 11:30 PM

Hi,

Quote:

Do you think a 7 H 250 mA 60 ohm choke would do (Lundahl LL1673 / 7H) if I increase the value of the filter capasitors?

Sure.

Quote:

I calculated that using a 280 V xformer and this 7 H 60 ohm choke will give me about 5 Volts more compared to the original setup. This won't do any harm, will it?

That's absolutely neglible. You may even find it to deviate to either end of the scale but better to have a little too much voltage to start with than not enough.

Cheers,

macce78 · 29th November 2004, 06:56 AM

OK, thanks Frank

25th November 2004, 07:50 PM	#1
macce78 diyAudio Member Join Date: Jan 2004 Location: Southern Finland	amp-schematic questions... Hi! I'm finally starting my first valve amp project, and as I Googled around for a nice and simple (read: cheap) SE-design I ran in to this:http://www.lundahl.se/claus_b_se.html. What do you guys think of this one, and is it a suitable project for a noob? Is it OK to run the amp with a 230V // 280-0-280 0,190A / 6,3V 4A / 5V 2A transformer if I connect the 280 V windings in parallel? That's the closest match I can find here in Finland, and I don't have a credit card wich makes ordering from abroad a bit tricky... (it's actually quite hard to find the right parts to any design, and I'm pretty amazed that only the transformer is missing from this one.) cheers, Marcus

26th November 2004, 12:32 AM	#2
fdegrove diyAudio Senior Member Join Date: Aug 2002 Location: Belgium	Hi, That xformer should be O.K. You could even arrive at the same voltage values if you could source a 10H 200mA choke with a DCR lower than 200 R. It could be made as a first DIY amp I suppose but be aware of the high voltages involved. Just one note: I wish Mr. Byrith would have picked a 6SL7 or 12AT7A (for instance) iso that dreaded 12AX7........ And another one: variable feedback often means that unless you have the necessary mearuring tools you'll never be sure when you have the correct setting. That's enough to drive alot of people bananas... Cheers, __________________ Frank

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Some questions about schematic symbol	Nordic	Power Supplies	2	17th May 2008 06:47 AM
Jolida schematic questions	JayH3	Tubes / Valves	13	27th March 2008 08:04 AM
Amp Hack schematic questions	rafaelblock	Tubes / Valves	12	13th March 2008 09:35 PM
some schematic questions by newbie help!	Raj1	Tubes / Valves	19	27th September 2003 12:34 AM
schematic questions	Magnetmaz	Parts	14	19th December 2002 05:09 PM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

28th November 2004, 07:22 PM	#3
macce78 diyAudio Member Join Date: Jan 2004 Location: Southern Finland	Do you think a 7 H 250 mA 60 ohm choke would do (Lundahl LL1673 / 7H) if I increase the value of the filter capasitors? That's the only choke I found that can handle 250 mA with current. I calculated that using a 280 V xformer and this 7 H 60 ohm choke will give me about 5 Volts more compared to the original setup. This won't do any harm, will it?

29th November 2004, 06:56 AM	#5
macce78 diyAudio Member Join Date: Jan 2004 Location: Southern Finland	OK, thanks Frank