The first channel of my gainclone is 2 hours old.
300VA, 25VAC (34 DC or so), 32mV DC offset, VERY cheap 450k linear pot, 12cmx7cm aluminium heatsink, 1000uF Panasonic FC caps, 25A bridge diodes, LM3875, inverting configuration, pin7 to ground, 220k in feedback loop, 10k in to pin 8. No input cap, fed straight from my CD player.
Sound: The bass peformance is EXCEPTIONAL-resolution, depth, weight is all there. Unbelievable! I actually laughed listening to one Marcus Miller track, the bass was that fantastic...
Mids so far are very hi resolution, oodles of detail and again incredible clarity.
Highs as far as I can tell are a bit hard, just a bit. I imagine that will improve with time....
Sound also appears transparent (again harder to judge with one channel) and transients are ver quick.
Only obvious drawback is in the upper mids, which seem a bit tizzy, again time will tell.
Conmpared with an El34-based push-pull power amp, I prefer the gainclone by far. Also the NAIM 140 power amp, wih a 62 pre-amp sounds relatively bland by comparison.
Took me three hours to build the first channel and I am sure the second will take about 1 hour, now that I am sure of everything!
For anyone considering the LM3875, buy it, build it, listen to it. VERY worthwhile.
Regards
Ryan
300VA, 25VAC (34 DC or so), 32mV DC offset, VERY cheap 450k linear pot, 12cmx7cm aluminium heatsink, 1000uF Panasonic FC caps, 25A bridge diodes, LM3875, inverting configuration, pin7 to ground, 220k in feedback loop, 10k in to pin 8. No input cap, fed straight from my CD player.
Sound: The bass peformance is EXCEPTIONAL-resolution, depth, weight is all there. Unbelievable! I actually laughed listening to one Marcus Miller track, the bass was that fantastic...
Mids so far are very hi resolution, oodles of detail and again incredible clarity.
Highs as far as I can tell are a bit hard, just a bit. I imagine that will improve with time....
Sound also appears transparent (again harder to judge with one channel) and transients are ver quick.
Only obvious drawback is in the upper mids, which seem a bit tizzy, again time will tell.
Conmpared with an El34-based push-pull power amp, I prefer the gainclone by far. Also the NAIM 140 power amp, wih a 62 pre-amp sounds relatively bland by comparison.
Took me three hours to build the first channel and I am sure the second will take about 1 hour, now that I am sure of everything!
For anyone considering the LM3875, buy it, build it, listen to it. VERY worthwhile.
Regards
Ryan
Well done Dr H and welcome to the laughing audiophiles club! 
Yes, you can't help but smile when you hear the sound and I laughed a few times too!
I have heard this with some recordings too and IMHO this is possibly down to the GC faithfully reproducing a poor recording. In other words, it is so clear that it shows up problems that we couldn't hear with a lesser amp.
I expect that this is more or less prominent depending on the speakers used/crossover frequency/tweeter/etc.
Yes, you can't help but smile when you hear the sound and I laughed a few times too!I have heard this with some recordings too and IMHO this is possibly down to the GC faithfully reproducing a poor recording. In other words, it is so clear that it shows up problems that we couldn't hear with a lesser amp.
I expect that this is more or less prominent depending on the speakers used/crossover frequency/tweeter/etc.
Welcome to the club Dr. H.
One of the best moments i have ever had was having a friend come over who has a krell/B&W combo worth about 15K US and seeing his jaw hit the floor when he heard my GC/fostex horn combo (which i had about 400$ wrapped up into).
Have fun and believe me it can get better.
ron
One of the best moments i have ever had was having a friend come over who has a krell/B&W combo worth about 15K US and seeing his jaw hit the floor when he heard my GC/fostex horn combo (which i had about 400$ wrapped up into).
Have fun and believe me it can get better.
ron
Fostex fe-103e horns
I have since re-designed the horns to have a greater efficency.The new design has the angled baffel going up to the top instead of the mini baffel , this provides for a better image and an increased soundstage.The wings on the lower have been re-designed for a sectioned 4.5" OD, 1/4" wall PVC pipe as i have simmed the wave front (fluid dynamics program) and the wavefront is more coherent if it wraps smoothly around the mouth exit(instead of a 45 deg flat plane) and exits 180 deg from the primary mouth direction.
This was an attempt to provide for an apt. size simple to construct horn with a small footprint. It dosent have quite (within 10%) the efficency of either a traxix or exponential/hyperbolic flare but has the advantage of less LF distortion.My next design will be expo/hyper flare using the fostex Fe-108e driver.Any questions please contact roncla@txucom.net.
ron
http://community.webtv.net/roncla/FOSTEXfe103ehorns
I have since re-designed the horns to have a greater efficency.The new design has the angled baffel going up to the top instead of the mini baffel , this provides for a better image and an increased soundstage.The wings on the lower have been re-designed for a sectioned 4.5" OD, 1/4" wall PVC pipe as i have simmed the wave front (fluid dynamics program) and the wavefront is more coherent if it wraps smoothly around the mouth exit(instead of a 45 deg flat plane) and exits 180 deg from the primary mouth direction.
This was an attempt to provide for an apt. size simple to construct horn with a small footprint. It dosent have quite (within 10%) the efficency of either a traxix or exponential/hyperbolic flare but has the advantage of less LF distortion.My next design will be expo/hyper flare using the fostex Fe-108e driver.Any questions please contact roncla@txucom.net.
ron
http://community.webtv.net/roncla/FOSTEXfe103ehorns
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