Which amp should I built for my 16 ohm speakers?

ajohn · 12th March 2010, 06:14 AM

My speakers' impedance is 16 ohm. Which Pass Labs amp should I build? I have some experience building DIY tube pre-amps but in fact I possess very basic electronics knowledge.

Zen Mod · 12th March 2010, 09:24 AM

you didn't said what's efficiency of your speakers , but I presume that they're easy to drive ;

anyway - one of solutions is on first few pages of F4 thread - F4 with just one pair of output mosfets ;

F4 is "just" current buffer , so tube pre is welcome , with usual tube voltage swing

so - find latest F4 schematic ( probably is on First Watt site as pdf file ) , leave just one output pair of mosfets in place , and enjoy

if you have some more questions - just ask

flg · 12th March 2010, 12:22 PM

Probably not a bad idea

But, in that case I would pump up the bias a little more

Maybe 1A or so... Just my 2 cents.

Zen Mod · 12th March 2010, 02:01 PM

Quote:

Originally Posted by flg

Probably not a bad idea

But, in that case I would pump up the bias a little more

Maybe 1A or so... Just my 2 cents.

it really depends of nature of his speakers

in any case - valid and good note

ajohn · 12th March 2010, 02:22 PM

I don't know the sensitivity for sure but it should be about 95 db.
Is the F4 easy to build?

flg · 12th March 2010, 04:36 PM

Well, 95 is a good eff # for most people

I acctually made a little mistake in my post

"I" would actually try to run the output FETs in their most reliable/linear range. And to me that would be about 30-35W dissapation. 65C Heatsink temp max. Considering maybe 22-23Vds. 1.4 or 1.5A Iq. A 70W heatsink is not that difficult

There are other factors but... For instance, you can gain a bunch by insolated H.S. and Arctic Ice with no pads, mica etc. ect.

ajohn · 14th March 2010, 11:42 PM

Please tell me why a F4 is more suitable for my 16 ohm speakers rather than, say, the F5.

Bill Fuss · 15th March 2010, 12:38 AM

It isn't necessarily, mathematically speaking. A 16ohm driver pulls less current than an 8ohm and would like a proportionally higher rail voltage. You would be optimising the amp for that particular load and could do it by lowering the bias current simply by eliminating some output transistors. IMHO the F4 would be a better choice if your tube pre has enough voltage swing.

But that's just my opinion.

12th March 2010, 06:14 AM	#1
ajohn diyAudio Member Join Date: Jan 2007 Location: Hong Kong	Which amp should I built for my 16 ohm speakers? My speakers' impedance is 16 ohm. Which Pass Labs amp should I build? I have some experience building DIY tube pre-amps but in fact I possess very basic electronics knowledge.

12th March 2010, 09:24 AM	#2
Zen Mod diyAudio Member Join Date: Jan 2003 Location: ancient Batsch , behind Iron Curtain	you didn't said what's efficiency of your speakers , but I presume that they're easy to drive ; anyway - one of solutions is on first few pages of F4 thread - F4 with just one pair of output mosfets ; F4 is "just" current buffer , so tube pre is welcome , with usual tube voltage swing so - find latest F4 schematic ( probably is on First Watt site as pdf file ) , leave just one output pair of mosfets in place , and enjoy if you have some more questions - just ask __________________ my Papa is smarter than your Nelson ! tnx to clean thread ; Cook Book ; PSM LS Cook Book ; Baby Diyaudio FORUM ; BAF Forum & Gallery;I'm dumb

12th March 2010, 12:22 PM	#3
flg diyAudio Member Join Date: Jul 2005 Location: North East	Probably not a bad idea But, in that case I would pump up the bias a little more Maybe 1A or so... Just my 2 cents. __________________ “Be who you are and say what you feel because those who mind don't matter and those who matter don't mind.” Dr. Seuss

12th March 2010, 04:36 PM	#6
flg diyAudio Member Join Date: Jul 2005 Location: North East	Well, 95 is a good eff # for most people I acctually made a little mistake in my post "I" would actually try to run the output FETs in their most reliable/linear range. And to me that would be about 30-35W dissapation. 65C Heatsink temp max. Considering maybe 22-23Vds. 1.4 or 1.5A Iq. A 70W heatsink is not that difficult There are other factors but... For instance, you can gain a bunch by insolated H.S. and Arctic Ice with no pads, mica etc. ect. __________________ “Be who you are and say what you feel because those who mind don't matter and those who matter don't mind.” Dr. Seuss

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12th March 2010, 02:22 PM	#5
ajohn diyAudio Member Join Date: Jan 2007 Location: Hong Kong	I don't know the sensitivity for sure but it should be about 95 db. Is the F4 easy to build?

14th March 2010, 11:42 PM	#7
ajohn diyAudio Member Join Date: Jan 2007 Location: Hong Kong	Please tell me why a F4 is more suitable for my 16 ohm speakers rather than, say, the F5.

15th March 2010, 12:38 AM	#8
Bill Fuss RIP Join Date: Oct 2005 Location: Central Florida	It isn't necessarily, mathematically speaking. A 16ohm driver pulls less current than an 8ohm and would like a proportionally higher rail voltage. You would be optimising the amp for that particular load and could do it by lowering the bias current simply by eliminating some output transistors. IMHO the F4 would be a better choice if your tube pre has enough voltage swing. But that's just my opinion.

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