F5 power amplifier

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#6,445
vitalica said:
Please tell me, what power have bridged the 4 ohm F5 ?
I want to use it to Open Baffle for 2 x Eminence 15 ".
Thank you very much !
Click to expand...

don't bridge it for 4 ohms

because you're anyway willing to make two stereo F5 and to bridge them - you'll have 4 "usual" channels ..... and you have 4 Eminence bass drivers ;
connect one bass to one channel - so called "vertical biamping"



much better drive conditions than bridged 4 ohms , where each channel see just 2 ohms
 
#6,448
vitalica said:
Please tell me, what power have bridged the 4 ohm F5 ?
I want to use it to Open Baffle for 2 x Eminence 15 ".
Thank you very much !
Click to expand...

I dont know if there is a need for this.

I use just a lonely F5 bi-amped with each channel driving 2 Alpha woofers.
The power seems there and well behaved. The top end I run the amp of the day, but the F5 surely is one of the best on top and bottom end for me.
 
#6,450
Can anybody direct me to instructions for setting the bias and any other complicated aspects there might be in constructing the F5 please, before I decide if I'm up to the task? I feel that I probably am capable, but had previously been attracted to the notion of building the Quad 405 Mk2, partly on the basis that it has dynamic bias setting, and remains within spec without adjustment until component failure. I'd prefer to build the F5, however, as it's almost certainly a better amp, which is saying something. I guess what I'm really asking is, does setting the bias on the F5 involve any tools beyond a decent soldering kit and a DMM?

Many thanks
Lucas
 
#6,451
LucasAdamson said:
Can anybody direct me to instructions for setting the bias and any other complicated aspects there might be in constructing the F5 ................................ I guess what I'm really asking is, does setting the bias on the F5 involve any tools beyond a decent soldering kit and a DMM? Lucas
Click to expand...

Two DMMs would be usefull, one to watch the bias on one mosfet and the second to watch the DC offset on the output. But, it could be done with just the one switching the leads back and forth, back and forth, back and forth :sad:
Just remember to start with the pots set at their lowest value.

The F5 pdf on the First Watt web has instructions, also it's repeated numerous times in this thread.
 
#6,456
vitalica said:
Hi Tea-Bag ,
Please tell me if I understand well ...
Each Alpha 15 is run at you from a channel F5?
I mean you vertical-biamping?
I have tried but ... Supravox with an F5 is heard louder🙂

Thanks!
Click to expand...

Vitalica,

One F5 normal stereo kit drives 4 total alphas OB, two on left channel two on the right. The drive is like 1.5 or 2 ohms in parallel, but this is not a problem for this puppy. I use the T-Bass booster as well, and it does give a little more juice on the lower end, but still rolls off fast after 35hz. A electric cross over could give some bass boost like this too.

I have not tried vertical bi-amping, but I do have an army of amp's to work with. I will settle for this for now, it works. I am sure running one F5 per two Alpha's may bring more low end control, but these are quite efficient speakers.
 
#6,457
MOSFET and JFET matching sockets

Does anyone have part numbers for machine sockets to use for temporarily holding Mosfets and another one for JFets -- for use in testing and/or matching?

I haven't done any testing yet. But, I figure it would be a good idea to be ready just in case I run into any issues. Plus, I have to order some parts after the holidays.

Thanks,
Steve
 
#6,458
Hi Tea-Bag,

Now I understand🙂
And I connected just like you - a single F5 to 4xEminence by active XO.
Bass very good, but did not know if I can go to 2 ohm .
The drop-biamping version I liked more-much, bass more accurate and powerful.

Thank you very much and ...Merry Christmas!🙂🙂
 
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