I've found documents from my 1986 purchase from Audio Concepts in Wisconsin. I was mistaken, that a single Strat could be driven directly.
They recommend a series resistor of 1.5 ohms with a single Strat.
Guess I'll be using the transformers.
PS sorry for the off topic
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And I was thinking about 15V trafos, with raised bias
Wasnt there something with input driver stage being at the limit with the original supply
Hi tinitus,
my balanced F5 (EUVL's version, see http://www.diyaudio.com/forums/showpost.php?p=1542055&postcount=1216) runs with 15VAC and 1.6A bias current. But I used 2SK1530/2SJ201 instead of the original IRF types. It sounds great!
Uwe
I routinely push these parts to as high as 40V in my own
stuff. They seem to have been spec'd at lower voltage for
Gate current. If you can put up with higher Gate current,
then you'll find them actually breaking down around 42-43 V.
Not that I recommend that you build an amp on this
assumption...
And has no one mentioned cascoding these?
stuff. They seem to have been spec'd at lower voltage for
Gate current. If you can put up with higher Gate current,
then you'll find them actually breaking down around 42-43 V.
Not that I recommend that you build an amp on this
assumption...
And has no one mentioned cascoding these?
.....
And has no one mentioned cascoding these?
even my tongue is starting to bump , repeating that
I got it to work (this was perhaps a year ago) but the pair of F5's -- 2 sets of 2-- use Fairchild devices.
System needs a few more dB gain to drive F5
I've got a channel of the F5 up and running and I noticed my input to the
amplifier isn't sufficient to get to full output power. Unfortunately, my
speakers only have about 82 dB efficiency so I know I won't get to ear bleeding
levels, but I would at least like to maximize the output. Given the output of my
cd player, I need about 2-3 dB more gain. Any suggestion on how to achieve
this without destroying the quality of the F5? Thanks.
I've got a channel of the F5 up and running and I noticed my input to the
amplifier isn't sufficient to get to full output power. Unfortunately, my
speakers only have about 82 dB efficiency so I know I won't get to ear bleeding
levels, but I would at least like to maximize the output. Given the output of my
cd player, I need about 2-3 dB more gain. Any suggestion on how to achieve
this without destroying the quality of the F5? Thanks.
fritz,
I beleive others have had success changing the feedback resistors (100 ohm 3 watts) to 150 ohms to get higher gain.
Hi
Do you think a 24" length of this extrusion will suffice for a stereo F5? This means about 6" per transistor, and the charts seem to show that it'll just about make it (~20 degrees/30 watts for a single 6" length). If not, can someone recommend a suitable profile from the Aavid site? I'd like to have a backup in case my first set of heatsinks is not sufficient.
http://www.aavidthermalloy.com/cgi-bin/exdisp.pl?Pnum=62725&LengthUnits=in&ExLength=3&airflow=57.2
Do you think a 24" length of this extrusion will suffice for a stereo F5? This means about 6" per transistor, and the charts seem to show that it'll just about make it (~20 degrees/30 watts for a single 6" length). If not, can someone recommend a suitable profile from the Aavid site? I'd like to have a backup in case my first set of heatsinks is not sufficient.
http://www.aavidthermalloy.com/cgi-bin/exdisp.pl?Pnum=62725&LengthUnits=in&ExLength=3&airflow=57.2
What's the max output of your source?
For the peak output of the F5 (54W pk, 24W continuous in to 8R) you'll need 3.7V input, assuming that the amp is giving 15dB of gain. Most preamps should be capable of delivering 3.7V
I actually have that calc filed away in my bookmarks
When you say 3.7V, is that RMS or peak? Of course I'll be safe if that's peak, but if it's RMS I'll need about 10dB of gain from my sources (I have the 'Balanced Line stage' also from the Pass website that I could build for this).
It's peak.
My cd source puts out the standard 2Vrms which is about 2.8Vpk. My preamp
has no gain so I need the extra gain to get from 2.8V to 3.7V. I breadboarded
a quick gain stage that added about 10dB and noticed a jump in volume,
but it was too noisy for me to turn it all the way up. I only need about 3dB
but 10 is probably easier to build. Thanks.
I will give this a try since I only need a small increase in gain. I assume this
results in less feedback and so maybe a little less stability? Right now it is rock
solid. Thanks for the input Tea-Bag.