mrdave45, maybe it would be cheaper/less hu-har to build another F4 and monobloc them.
Mr. Pass says "The F4 is Class A impedance converting amplifier, having no voltage gain or feedback. Its input impedance is 47,000 ohms, and its output impedance is about 0.2 ohms. It is suitable for driving a high sensitivity loudspeaker with the output voltage of a preamp or other line-level audio source. It is also useful with a less sensitive loudspeaker in a bi-amped configuration where it takes input from the output of a conventional amplifier.
As a stereo amplifier with single-ended inputs and outputs, it will deliver up to 25 watts into 8 ohms with a damping factor of 40. It will do 50 watts into 4 ohms, and as a mono-block amplifier with parallel inputs and outputs, it will do about 100 watts into 2 ohms. As a mono-block amplifier with balanced inputs and outputs the power output rating is 100 watts into 8 ohms at 1%."
brian.
Mr. Pass says "The F4 is Class A impedance converting amplifier, having no voltage gain or feedback. Its input impedance is 47,000 ohms, and its output impedance is about 0.2 ohms. It is suitable for driving a high sensitivity loudspeaker with the output voltage of a preamp or other line-level audio source. It is also useful with a less sensitive loudspeaker in a bi-amped configuration where it takes input from the output of a conventional amplifier.
As a stereo amplifier with single-ended inputs and outputs, it will deliver up to 25 watts into 8 ohms with a damping factor of 40. It will do 50 watts into 4 ohms, and as a mono-block amplifier with parallel inputs and outputs, it will do about 100 watts into 2 ohms. As a mono-block amplifier with balanced inputs and outputs the power output rating is 100 watts into 8 ohms at 1%."
brian.
Thanks Brian. It's actually going to be for anonther set of speakers. My open baffles and f4 live in the lounge. I may well build another f4 for that setup too.
I'm most likely going to build some studio monitors from troels gravesend site and speakers of near field size tend to be a bit less efficient. But instead of building a single stereo higher powered amp I was thinking of biamping.
I'm most likely going to build some studio monitors from troels gravesend site and speakers of near field size tend to be a bit less efficient. But instead of building a single stereo higher powered amp I was thinking of biamping.
Ok I see. In that case you might have to carefully consider the layout as i had a right faff on with emi in a 3u case. Thought I had grounding issues or a fault somewhere. Turned out that using one 625va toroid I had to have it right at the front of amp away from the very sensitive inputs. Of course, I'm sure you know all this. Good luck.
brian.
brian.
Hi 6l6, yes, the f4 and open baffles ~94db go plenty loud enough. I was considering another for that system so I could biamp, not so much for volume but hoping it would be an uograde. That's my main hifi system in my living room. I also have a recording studio completely separate to this. I need to replace a pair of supposedly high end near fields, hence another amp and speakers. Tbf 25w a side probably would be enough if they are 90db speakers I build.
Had not thought about the burning amps. I'll check that out.
Had not thought about the burning amps. I'll check that out.
Hello new friends! Total nube over here and I've got a finished F5 sitting on my table and I'm getting nothing across the resistors no matter how much I crank the pots. It sounds like the same problem 6L6 had in his guide, but I'm not exactly sure and I may have taken unwise liberties with the design.
First off, I omitted R15-18 leaving only R19-20 to limit current. I'm also running 32V rails which are measuring 34V. Aside from that it's built to specs on DIYaudiostore boards. I'm in totally uncharted territory here and would appreciate any advice to be proffered.
First off, I omitted R15-18 leaving only R19-20 to limit current. I'm also running 32V rails which are measuring 34V. Aside from that it's built to specs on DIYaudiostore boards. I'm in totally uncharted territory here and would appreciate any advice to be proffered.
http://www.diyaudio.com/media/build-guides/diyaudio-f5-build-guide.pdf
Highly useful for F5 DIY folks
Have a nice day
Highly useful for F5 DIY folks
Have a nice day
Yes, thanks for the link, i read it before. It did not answer my question though.
I got F5 behaving well on the floor, no problem. Before i embark on puting it into box, i need to decide on the pot. I use these amps with active crossovers and its usefull to have way to adjust each section separately.
I got F5 behaving well on the floor, no problem. Before i embark on puting it into box, i need to decide on the pot. I use these amps with active crossovers and its usefull to have way to adjust each section separately.
Link was not intended to answer Your question no doubt :
An illustrated guide to building an F5
Precise answer(s) to precise tech questions :
What audio source output and preamp output impedance is ?
Greetings
My two main systems are both bi-amplified. Typically I split the signal at ~160Hz, sending higher pass to high quality class a amp for mids and tweeters section. I leave passive crossover for tweeter and breakup cure for mid in place, if there.
Lower pass below goes to any class ab amp, powering the woofers, typically without any passive crosover, saving on the coils.
I do like to have aditional volume controls on each amp, not just master volume on the active crossover. This allows to use speakers with different efficiencies. Typically you adjust woofer section litte higher without any need for lpads in mids and tweeter. No need to waste class a output.
I have made quite a number of active crossovers recently, and now i am quite satisfied. I am already looking to build 3 or 4 way one. I can't stand the opa based active crossovers, somehow they sound different.
chrisb, i wish i had time...i am so far with my blogs that i would have to spend weeks to catch up
Lets see, briefly, main system has volume pot, jlh buffer, passive upper pass (just a cap and resistor out), active lower pass with ebay subwoofer circuit, with mods by andrea ciufoli
Second system has volume pot, kaneda upper pass (i have a thread about it), lower pass is ebay stuff as above.
Third active crossover is in use in my diy audio room, has volume pot followed by simple jfet buffers, feeding passive upper and lower passes. Sounds great actually, inspite slightly higher distortion than above two.
My measuring capabilities are limited, but i collecled some spectrum data.
Last few days i optimized crossoved for little bookshelf, AC130 with Benton planar. I will post fr sweep, pretty amazing.
