I've built some Carfrae little Big Horn replicas. They are 105db per watt efficient and I'm struggling with volume control.
What's the best way to improve this. Do Fostex transformer attenuators work well or would adding a couple of resistors to the volume pot on my integrated amp be OK. I'd estimate the output of my modified amp at 15watt tops.
I guess the big question is:
Is it better to attenuate before or after amplification when you've got more gain than you can handle?
What's the best method?
What's the best way to improve this. Do Fostex transformer attenuators work well or would adding a couple of resistors to the volume pot on my integrated amp be OK. I'd estimate the output of my modified amp at 15watt tops.
I guess the big question is:
Is it better to attenuate before or after amplification when you've got more gain than you can handle?
What's the best method?
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Is this a joke? Who complains about too much sensitivity of their speakers - Just don't turn the volume up high. I have tractrix FLH's that are 109dB sensitive and I never complain.
These are BLH's so I assume you are saying the bass gain from the back wave is higher than the front cone output? Adding stuffing behind the driver in the back chamber will attenuate the BLH output.
Very nice work on the horns by the way.
A measurement showing relative output of BLH vs front radiator output would be great if you have it.
These are BLH's so I assume you are saying the bass gain from the back wave is higher than the front cone output? Adding stuffing behind the driver in the back chamber will attenuate the BLH output.
Very nice work on the horns by the way.
A measurement showing relative output of BLH vs front radiator output would be great if you have it.
Ideally you want to decrease the gain of one of your pieces of electronics...
What is your entire chain?
dave
Backloaded Lowther drivers driven by Triode wired Audio Innovations 500, Hypex plate amp and Seas Subwoofer and Passive radiator combination in the base/bass units. Original Carfraes used a single subwoofer and a port. The carcas kit is provided by Creation Audio in Australia under licence from Jim Carfrae.
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Integrated Amp at the moment including the Phono stage. Replacing the whole lot with a Pre Power and Phono amp is an option but not a cheap one
Bottlehead paramours with 3watt output might be nice!
Not optimally biased but for a lark you could try ECC81 or 82 (or 12BH7) in place of V3.
dave
"Not optimally biased but for a lark you could try ECC81 or 82 (or 12BH7) in place of V3.
dave"
That's a pretty good suggestion on the face of it
http://www.drtube.com/datasheets/ecc81-philips1969.pdf
http://www.drtube.com/datasheets/ecc83-philips1970.pdf
dave"
That's a pretty good suggestion on the face of it
http://www.drtube.com/datasheets/ecc81-philips1969.pdf
http://www.drtube.com/datasheets/ecc83-philips1970.pdf
Truly gorgeous.
High efficiency is no virtue, at least since 1965. Paul Klipsch used to say he only wanted 5 clean watts. Maybe the fix is to get a bigger knob on the amp so you can more easily dial 9.5, 9.6, etc. (like the famous "11" on the volume control in Spinal Tap movie). Even so, the net S/N when your ear is near the horn has to disparage the whole fancy system.
Hard to endorse or find feasible any of the electric fixes downstream of the amp output. I wonder if there's anything acoustic - like stuffing stuff in the horn - that makes sense but that you'd never think of doing ordinarily?
Ben
High efficiency is no virtue, at least since 1965. Paul Klipsch used to say he only wanted 5 clean watts. Maybe the fix is to get a bigger knob on the amp so you can more easily dial 9.5, 9.6, etc. (like the famous "11" on the volume control in Spinal Tap movie). Even so, the net S/N when your ear is near the horn has to disparage the whole fancy system.
Hard to endorse or find feasible any of the electric fixes downstream of the amp output. I wonder if there's anything acoustic - like stuffing stuff in the horn - that makes sense but that you'd never think of doing ordinarily?
Ben
Another good Idea
Quite a bit better - bit cleaner sounding too!Tubestore recommended 12AY7 valves as being a closer match than ECC81 with a gain factor of 44. Only need one so I've put in an order.
Thanks for some good advice. I used to drive insensitive AE1 Mk1 Speakers (8ohms) from the 16ohm tap so why not drive Sensitive Carfrae's from the 4ohm tap
In the same situation as yours, I am using autoformers like this one: Apart Audio ? Sounds like the right choice
Don't use resistive divizors --not even L-pads-- because you lose amplifier's control over traductors. By using autoformers, in theory, output impedance get lower and you get even more control. More than that, you can use just headphone amplifiers; usualy they have not so low output inpedance, but using autoformers you improve that. I am using such a setup for just 104dB traductors in a normal dining-room and have lots of acoustic power.
Don't use resistive divizors --not even L-pads-- because you lose amplifier's control over traductors. By using autoformers, in theory, output impedance get lower and you get even more control. More than that, you can use just headphone amplifiers; usualy they have not so low output inpedance, but using autoformers you improve that. I am using such a setup for just 104dB traductors in a normal dining-room and have lots of acoustic power.
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