I'm building a set of high efficiency line source speakers (98db/w) and looking for suggestions for a high quality amplifier design with balanced inputs. I want to build monoblocks that will be located near each speaker which necessitates long interconnects. The speakers are a nominal 8 ohm load.
I'm actually almost done with a pair of F5T monoblocks (two output pair, no diodes, cascoded, 28v rails), but I'm using Jensen transformers for balanced inputs. I started building these before I decided to build the more efficient speakers, so now I'm wondering whether there might be a better option.
I have active servo-controlled open baffle stereo subs which will handle up to 80hz or so, so the amp doesn't have to "plumb the depths". With this kind of efficiency (and a line source), I don't think I need more than single digit watts.
Suggestions for a low-power, balanced-input, super-high-quality SS amp design? I'm obviously going to finish the F5T (should be able to power up one channel this weekend), but always thinking about the next project or modification.
I'm actually almost done with a pair of F5T monoblocks (two output pair, no diodes, cascoded, 28v rails), but I'm using Jensen transformers for balanced inputs. I started building these before I decided to build the more efficient speakers, so now I'm wondering whether there might be a better option.
I have active servo-controlled open baffle stereo subs which will handle up to 80hz or so, so the amp doesn't have to "plumb the depths". With this kind of efficiency (and a line source), I don't think I need more than single digit watts.
Suggestions for a low-power, balanced-input, super-high-quality SS amp design? I'm obviously going to finish the F5T (should be able to power up one channel this weekend), but always thinking about the next project or modification.
Stay with the F5T, you'll have some mods to do to reduce noise and hum, because of the high speaker efficiency.
You're a step ahead already with lower hum, because of the monoblocks and input transformers.
Can your preamp drive the long cables?
You're a step ahead already with lower hum, because of the monoblocks and input transformers.
Can your preamp drive the long cables?
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I'm using a Parasound JC2 preamp which has 60 ohm output impedance. I'm current driving 5M interconnects to a Parasound JC5 amp. I'll need to increase the interconnects to about 7M to reach the monoblocks, but I don't think that will be a problem for the JC2.
If I'm happy with the sound from the F5T, I may swap out the transformers (currently using Antek 400VA 25V for each monoblock) for 20V versions which I happen to have just to reduce heat.
I built the F5T using XRKAudio's Smooth as Butter PS.
If I'm happy with the sound from the F5T, I may swap out the transformers (currently using Antek 400VA 25V for each monoblock) for 20V versions which I happen to have just to reduce heat.
I built the F5T using XRKAudio's Smooth as Butter PS.
I listen on 101 db 1w 1m speakers all the time, and I use an amp with 25 v peaks available, 70 W.
My base level is 1/8 W, 1vav into 8 ohms, but when the cannon goes off in 1812 overture, I want it to be impressive. 55 db s/n just on the Mercury living presence LP's, more in Telearc CD's.
If you're listening to strumma/strumma singer-songwriter with acoustic guitar, or living strings easy listening, you don't need as much crest factor in your amps.
With 7 m to drive to amp, type cable matters. Twisted pair on stereo phone plugs is the way to go, which may be why you are looking for balanced input. I have a 4 m run, was getting hum with RCA coax cable, reduced it by putting a PV8 mixer to drive the twisted pair between my RIAA mixer near the turntable and the power amp over between the speakers. I'm using Peavey cs800s as power amp now, which is overkill on watts, but it does have the balanced input receiver built in. No room to stuff a +-15 supply and op amp board in my dynakit ST120, which is the amp that runs 1/8 w most of the time but peaks at 70 w for brief bursts.
The Peavey was cheapest solution anyway, $100 used +a 50 cent cap, a $1 ntcr the cap blew, and $20 in new mains caps just for reliability after 20 years with a bar band. .03% HD if you're not familiar with the model, and dead quiet at 1/8 W.
My base level is 1/8 W, 1vav into 8 ohms, but when the cannon goes off in 1812 overture, I want it to be impressive. 55 db s/n just on the Mercury living presence LP's, more in Telearc CD's.
If you're listening to strumma/strumma singer-songwriter with acoustic guitar, or living strings easy listening, you don't need as much crest factor in your amps.
With 7 m to drive to amp, type cable matters. Twisted pair on stereo phone plugs is the way to go, which may be why you are looking for balanced input. I have a 4 m run, was getting hum with RCA coax cable, reduced it by putting a PV8 mixer to drive the twisted pair between my RIAA mixer near the turntable and the power amp over between the speakers. I'm using Peavey cs800s as power amp now, which is overkill on watts, but it does have the balanced input receiver built in. No room to stuff a +-15 supply and op amp board in my dynakit ST120, which is the amp that runs 1/8 w most of the time but peaks at 70 w for brief bursts.
The Peavey was cheapest solution anyway, $100 used +a 50 cent cap, a $1 ntcr the cap blew, and $20 in new mains caps just for reliability after 20 years with a bar band. .03% HD if you're not familiar with the model, and dead quiet at 1/8 W.
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