The LF357 has a substantial 'sonic signature'. I am very familiar with this chip as I used it in my commercial GB1b amplifier and line stage of the GB1a preamp in 1988. I quickly replaced these with the quantum leap cleaner OPA627/637. Chalk and cheese.
It helps to bias the output stage as well of you will have a substantial forward path discontinuity ( big gain drop) at zero crossing (resistive load).
Cheers,
Greg
It helps to bias the output stage as well of you will have a substantial forward path discontinuity ( big gain drop) at zero crossing (resistive load).
Cheers,
Greg
The DC300A is biased AB+B for a reason.
If you want to re-engineer the thermal compensation, be my guest.
The Carver M1.5T also uses the LF357, but sounds much better than a DC300A. The DC300A is an old work horse, fine sounding hi-fi it never was.
IMO: Fix and use for bass, or let it go down the road.
If you want to re-engineer the thermal compensation, be my guest.
The Carver M1.5T also uses the LF357, but sounds much better than a DC300A. The DC300A is an old work horse, fine sounding hi-fi it never was.
IMO: Fix and use for bass, or let it go down the road.
Hi djk,
Have to agree. But I'm sure that, if used in a low duty full range 8 ohm hi fi application the heatsink could easily handle 25-50 mA of output transistor bias. After all, it has done a fair job of road PA use under worst conditions. I'll have a look at the thermal comp.
Cheers,
Greg
"fine sounding hi-fi it never was." I think this could be easily corrected.
Cheers,
greg.
Have to agree. But I'm sure that, if used in a low duty full range 8 ohm hi fi application the heatsink could easily handle 25-50 mA of output transistor bias. After all, it has done a fair job of road PA use under worst conditions. I'll have a look at the thermal comp.
Cheers,
Greg
"fine sounding hi-fi it never was." I think this could be easily corrected.
Cheers,
greg.
Hey djk,
You approach these things differently from me! I see a problem as a challenge - particularly with Crown as I see a lot of competent and inspired (for the time) design there, with few surmountable weaknesses.
Perhaps it's my outlook - low footprint, recycle, clean air to breathe, something left for future generations that I search for the good features and try to solve the weaknesses to 'save' the
value in the product.
It's just my way. It works for me. A GAIAN philosophy.
Yes my GB150D is fine with 52V supplies and would probably do about 120-140W depending on supply strength.
Cheers,
Greg
You approach these things differently from me! I see a problem as a challenge - particularly with Crown as I see a lot of competent and inspired (for the time) design there, with few surmountable weaknesses.
Perhaps it's my outlook - low footprint, recycle, clean air to breathe, something left for future generations that I search for the good features and try to solve the weaknesses to 'save' the
value in the product.
It's just my way. It works for me. A GAIAN philosophy.
Yes my GB150D is fine with 52V supplies and would probably do about 120-140W depending on supply strength.
Cheers,
Greg
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