I'm researching my future setup and I'd like to do it right the first time and build a b1 preamp and an F5. I've been looking at building the zaph sr71s. From what I've read the F5 requires sensitive speakers. Are th sr71s a bad match for this amp setup?
The F5 puts out 25 watts in class A, and 50 in AB. It will have plenty of power for a pair of the SR71s.
In my experience, the F5 is the best I've heard for driving my Proac clones, which are not exactly high efficiency.
In my experience, the F5 is the best I've heard for driving my Proac clones, which are not exactly high efficiency.
F5 needs about 4V peak at its input to produce 25W@8Ohms and most sources will give you 2.8V peak. Since B1 has zero gain you better go for the preamp with some gain (6-10dB) instead of searching for very sensitive speakers.
Search the forum for adequate preamps for F5 - there's plenty of them...
Yup noticed that after the edit window had closed that the B1 won't work as a preamp. Is there any way to build a preamp into the same case as the F5 and have it run off the same power supply without having to redesign things?
Yes Juma made a very nice preamp for driving the F5 to full power.
However I don't entirely agree that you can't use a B1. How many of us listen to music using the full power of the F5.
I connected my cd player direct to F5 to show my wife and she freaked out because it was too loud for her. So I actually need to attenuate the signal (not add gain to it).
My speakers are 89dB
It looks like those Zaph speakers are 85dB. I think it would be worthwhile having a look around at other speakers of higher efficincy that you also like.
I am not saying you can't use those Zaph speakers, they're just not ideal.
If you don't mind waiting and like open baffle speakers then Nelson's BOB might be worth considering.
However I don't entirely agree that you can't use a B1. How many of us listen to music using the full power of the F5.
I connected my cd player direct to F5 to show my wife and she freaked out because it was too loud for her. So I actually need to attenuate the signal (not add gain to it).
My speakers are 89dB
It looks like those Zaph speakers are 85dB. I think it would be worthwhile having a look around at other speakers of higher efficincy that you also like.
I am not saying you can't use those Zaph speakers, they're just not ideal.
If you don't mind waiting and like open baffle speakers then Nelson's BOB might be worth considering.
Does having lower sensitivity deaden the sound or does it simply mean that I have a more lilmited gain? I live in a very small apartment 18 sq meters, so I can't really crank it up, i sit roughly 3 meters from the speakers. The sr71 are ideal for me in that I can purchase the baffles and crossovers assembled and avoid the expense of purchasing numerous woodworking tools. I intend on running all audio into the f5 via an arcam rdac connected via usb to a mac mini, do i even need a preamp in this case?
in my experience lower speaker sensitivity leads to more "deaden" sound , even with more powerful amps
to my ears - gain is in speaker's gain
to my ears - gain is in speaker's gain
It may partly turn on the particular speaker, amp and room. One thing I noticed when using B-1 with F-5 with the Karma Indignia speaker, a small 2 way with about 85 db efficiency, is that when I switched out to the Mcintosh MC225 power amp, it suddenly sounded like a heavy hitter, way more toe tapping sound. When I equalized the volume between the F-5 and the MC225, the F-5 ate its lunch. With a preamp with gain, the F-5 sounded a bit more in the heavy hitter catagory. (By heavy hitter, I mean ability to get louder than you need)
Moving the speakers and the F-5 to an upstairs bedroom, (much smaller) and listening more near field, the B-1 really provides enough volume. While it is quite adequate, I still enjoy that setup better with a little gain on the pre's part.
With the Large E'waves, approx. 93 dB, they get rock and roll loud with the B-1.
I'd build the B-1 regardless. Very inexpensive, board is available from Pass Labs with matched fets, and sounds dynamite. With other amps, the B-1 had plenty of gain to drive them to maximum volume.
Russellc
Moving the speakers and the F-5 to an upstairs bedroom, (much smaller) and listening more near field, the B-1 really provides enough volume. While it is quite adequate, I still enjoy that setup better with a little gain on the pre's part.
With the Large E'waves, approx. 93 dB, they get rock and roll loud with the B-1.
I'd build the B-1 regardless. Very inexpensive, board is available from Pass Labs with matched fets, and sounds dynamite. With other amps, the B-1 had plenty of gain to drive them to maximum volume.
Russellc
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I made a pair of the SR71's...
http://www.diyaudio.com/forums/multi-way/167051-zaph-sr71-build-concrete.html
I use them with a pair of Peter Daniels Gain Clones @ around 55 watts...
http://www.diyaudio.com/forums/audi...kit-building-instructions-97.html#post2036286
I get plenty of volume running them with the B1 preamp and using an Apple TV as the source. My room is about 12 x 16 with me sitting at about 10-11 feet away.
I plan to make an F5 amp to go with these as soon as I can find the time!
erpiii
http://www.diyaudio.com/forums/multi-way/167051-zaph-sr71-build-concrete.html
I use them with a pair of Peter Daniels Gain Clones @ around 55 watts...
http://www.diyaudio.com/forums/audi...kit-building-instructions-97.html#post2036286
I get plenty of volume running them with the B1 preamp and using an Apple TV as the source. My room is about 12 x 16 with me sitting at about 10-11 feet away.
I plan to make an F5 amp to go with these as soon as I can find the time!
erpiii
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