Haha, no! Of course not. This 8 channel amp is for some friends of mine in California. Actually, it will be used to drive a special 4 synchronized driver horn sub woofer. The LSA verification builds are mostly done by Jhofland and Vunce. I will sometimes build something too. Like the LuFo or on my docket next is the SuSyLu. If that works we will commercialize it - being a 100w balanced SE Class A amp is kind of cool. I generally do the full system testing though where everything comes together on a plank amp. I then translate that to specs for a production run.
Yes, it’s amazing how fast parts add up. There are two custom DCDC converters: 6.3v filament heater and 90v B+. Lots of Susumu 0.5% metal thin film resistors for gain select on two channels, balanced input buffers, balanced output drivers and single ended drivers. Also solid state relays and gate drivers for speaker pop protection, logic circuits for safe startup and shutdown of the big IcePower amp, the tube buffer section itself,… superb design by Jhofland.
The bench got moved around so the active amp right now is the new IcePower 1200AS2 driven by the HyperSET sold state/E88CC hybrid buffer preamplifier. It’s got some cool looking VU meters. This combo will be the basis for the new EP 600.2SE amp that I am designing. Next to it is the TDA7293 Xmas amp. Both of these feed an A/B switch box. I have been listening to this combo for past couple of days. Very potent amp.
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Alpha 20 sings! Nice work.
Thanks for sharing, Anand.
Finished drilling and tapping one LuFo board. One more to go and I will be able to test SuSyLu.
Thanks for sharing, Anand.
Finished drilling and tapping one LuFo board. One more to go and I will be able to test SuSyLu.
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Both channels of LuFo work! Uneventful firing up for first sound on each channel separately. Then initial tests if balanced SuSyLu shows that bias is stable and output DC offset changes within 20mV through warmup cycle. Balanced common choke appears to be working.
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I've already done numerous amps, both tube (EL84) and impressive SS. (120 to 200w)
Among custom designing some radio gear and other electronic stuff.
So, for a big change, I decided to delve into a small amp for a refreshing change.
Really small, like a couple of watts, maybe 10.
Taken from a trashed reel-to-reel (VM) that had wing speakers, I salvaged the poor little amp board.
Stereo, all class A, 6 transistors (3 per ch) cascaded single-ended driving a pair of output transformers.
Initial testing surprised me, using the test speakers on my bench, so I'm giving it some respectable mods and we'll see how it goes.
Among custom designing some radio gear and other electronic stuff.
So, for a big change, I decided to delve into a small amp for a refreshing change.
Really small, like a couple of watts, maybe 10.
Taken from a trashed reel-to-reel (VM) that had wing speakers, I salvaged the poor little amp board.
Stereo, all class A, 6 transistors (3 per ch) cascaded single-ended driving a pair of output transformers.
Initial testing surprised me, using the test speakers on my bench, so I'm giving it some respectable mods and we'll see how it goes.
Looks like Anand is building the 4 ohm variant of the Alpha:
The IXYS p channel is driven by the VAS, a KSC1845, which works fine. Hugh has often used the combination of a KSC1845 and p channel IXYS with large gate capacitance as a CFP and there is never any issue of gate drive current. Perhaps you can ask Hugh in the
for the Alpha?
The IXYS p channel is driven by the VAS, a KSC1845, which works fine. Hugh has often used the combination of a KSC1845 and p channel IXYS with large gate capacitance as a CFP and there is never any issue of gate drive current. Perhaps you can ask Hugh in the
On the bench tonight is the SuSyLu max power stress test:
It worked fine and can run all day at max power. It's Class A so the amp actually runs cooler. Thermal efficiency is 100w/168w or 60%. So at max power the heatsinks only dissipate 68w vs 168w. The opposite of what happens on a Class AB amp.
SuSyLu is verified to put out close to 90Vpp into a 10ohm dummy load:
This is the o-scope trace - yellow is output after a signal divider - actual value is 89.7Vpp. Input signal is 4.64Vpp for overall gain of 25.6dB.
It worked fine and can run all day at max power. It's Class A so the amp actually runs cooler. Thermal efficiency is 100w/168w or 60%. So at max power the heatsinks only dissipate 68w vs 168w. The opposite of what happens on a Class AB amp.
SuSyLu is verified to put out close to 90Vpp into a 10ohm dummy load:
This is the o-scope trace - yellow is output after a signal divider - actual value is 89.7Vpp. Input signal is 4.64Vpp for overall gain of 25.6dB.