F5 power amplifier - Page 768

tinitus · 5th April 2010, 04:05 AM

It might work safer with device clips
Its tempting

I dont know if black anodizing are made in different ways
The only one I have tried to grind smooth with sandpaper showed a white and VERY tough layer of something between the black anodizing and the alu profile
Im sure that white layer isolates very effectively
Somehow I expect silver anodizing to be different

But the mounting screw may change things
Doing the needed thread can cause various things
Like material rise around the thread hole, etc

Renron · 5th April 2010, 05:50 AM

Pblossom,

Thank you for your input, yours is the only direct response from the "horses' mouth". They should know their products strengths and weaknesses.

Papa bought a case of Thermalcote for a reason.......Yes? Good enough for me!

Anodization is a great insulator, but fragile and prone to scratching.

I'll save the Arctic Silver for the CPUs, YMMV.

Ron

Renron · 06:15 AM

A lifetime (and 1/2) supply on Fleabay.
One pound of Thermalcote. LOL

Ron

Nelson Pass · 5th April 2010, 07:15 PM

Quote:

Originally Posted by Renron

Papa bought a case of Thermalcote for a reason.......

I did not say I bought it.

androuski · 5th April 2010, 07:30 PM

Hello Mr Pass,
I'm building an F5 amp, to feed a pair of 94db/2,83v speakers, do you think I'll need a preamp to get a realistic level ?
Thanks for sharing - this is my first pass diy project !

AndrewT · 5th April 2010, 07:42 PM

The gain of the F5 is ~6times (~+15dB)
the max signal from a cdp is ~2.1Vac.
The max signal from the F5 will be ~12.6Vac
This is equivalent to ~20W into 8ohms. Not quite full power.
The F5 sensitivity is just slightly more than most CDP and considerably more than lower voltage sources. A pre-amp with gain may be required depending on the voltage from your sources.

Now let's look at what SPL you can get.
20W is 13dBW.
The speakers are 94dB/W@1m.
The maximum SPL is ~107dB @1m
If your average level is 20dB below your maximum then your average listening level with zero attenuation from a 210mVac signal (-20dB ref 2.1Vac) will be ~87dB @ 1m. That is getting pretty loud for most listeners. But that requires a high maximum voltage source. Maximum average level will depend on your source voltage.

androuski · 5th April 2010, 08:31 PM

So,
for my domestic purpose, I guess It will be sufficent, with cdp or phono preamp, isnt'it ?

Bigun · 5th April 2010, 08:37 PM

Seems to me you don't need a preamp. But look on the bright side, if you find you need a little more gain you have a reason to build a nice preamp

Renron · 5th April 2010, 08:41 PM

Quote:

Originally Posted by Nelson Pass

I did not say I bought it.

Thanks for makin' us laugh Papa.

BTW, Love my F5!

Ron

a.wayne · 5th April 2010, 11:07 PM

What is the aversion to running a pre-amp with the F5 ? it seems that the gain is of some concern, No ? ...

5th April 2010, 05:50 AM	#7672
Renron diyAudio Member Join Date: Jan 2007 Location: Sacramento	Pblossom, Thank you for your input, yours is the only direct response from the "horses' mouth". They should know their products strengths and weaknesses. Papa bought a case of Thermalcote for a reason.......Yes? Good enough for me! Anodization is a great insulator, but fragile and prone to scratching. I'll save the Arctic Silver for the CPUs, YMMV. Ron __________________ "If it doesn't work properly, hope it catches on fire"- Nelson Pass @ BA3 "I fired up the prototype. Literally." The Prophet Pass.

5th April 2010, 08:37 PM	#7678
Bigun diyAudio Member Join Date: Jan 2009 Blog Entries: 2	Seems to me you don't need a preamp. But look on the bright side, if you find you need a little more gain you have a reason to build a nice preamp __________________ "The test of the machine is the satisfaction it gives you. There isn't any other test. If the machine produces tranquility it's right. If it disturbs you it's wrong until either the machine or your mind is changed." Robert M Pirsig.

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5th April 2010, 04:05 AM	#7671
tinitus diyAudio Moderator Join Date: Nov 2005	It might work safer with device clips Its tempting I dont know if black anodizing are made in different ways The only one I have tried to grind smooth with sandpaper showed a white and VERY tough layer of something between the black anodizing and the alu profile Im sure that white layer isolates very effectively Somehow I expect silver anodizing to be different But the mounting screw may change things Doing the needed thread can cause various things Like material rise around the thread hole, etc

5th April 2010, 07:30 PM	#7675
androuski diyAudio Member Join Date: Jan 2008	Hello Mr Pass, I'm building an F5 amp, to feed a pair of 94db/2,83v speakers, do you think I'll need a preamp to get a realistic level ? Thanks for sharing - this is my first pass diy project !

5th April 2010, 07:42 PM	#7676
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	The gain of the F5 is ~6times (~+15dB) the max signal from a cdp is ~2.1Vac. The max signal from the F5 will be ~12.6Vac This is equivalent to ~20W into 8ohms. Not quite full power. The F5 sensitivity is just slightly more than most CDP and considerably more than lower voltage sources. A pre-amp with gain may be required depending on the voltage from your sources. Now let's look at what SPL you can get. 20W is 13dBW. The speakers are 94dB/W@1m. The maximum SPL is ~107dB @1m If your average level is 20dB below your maximum then your average listening level with zero attenuation from a 210mVac signal (-20dB ref 2.1Vac) will be ~87dB @ 1m. That is getting pretty loud for most listeners. But that requires a high maximum voltage source. Maximum average level will depend on your source voltage.

5th April 2010, 08:31 PM	#7677
androuski diyAudio Member Join Date: Jan 2008	So, for my domestic purpose, I guess It will be sufficent, with cdp or phono preamp, isnt'it ?

5th April 2010, 11:07 PM	#7680
a.wayne diyAudio Member Join Date: May 2008 Location: Front Row Center	What is the aversion to running a pre-amp with the F5 ? it seems that the gain is of some concern, No ? ...