Hi. I found a BGW 250D for sale at a good price, but don't have any experience with these amps. What does it sound like?
The input op amp, LM318, is likely to be hissy at high gain. It is pin compatible with some others, so maybe it could be tamed with something more modern like OPA604, but some care may be necessary to prevent oscillation.
I do not own one. +-55 v with heat sink for 4 pairs of output transistors, So I would be tempted at the right price for just the transformer & heatsinks. If you're a bar band, you donot want to carry that much weight. For home parties the wattage is about right for a poolside setup. I do not see a DC detect and speaker relay, so the Peavey Crowns & QSC's are one up on protecting your 500 w party speakers.
I do not own one. +-55 v with heat sink for 4 pairs of output transistors, So I would be tempted at the right price for just the transformer & heatsinks. If you're a bar band, you donot want to carry that much weight. For home parties the wattage is about right for a poolside setup. I do not see a DC detect and speaker relay, so the Peavey Crowns & QSC's are one up on protecting your 500 w party speakers.
All of the parts for the BGW's appear to be still available, which can probably not be said for the Onkyo M-505 (although I'm still leaning towards it). The BGW has a full protection circuit, and there are no complaints of input noise.
I searched the opamp in question, and found that there is no suitable substitute.
I searched the opamp in question, and found that there is no suitable substitute.
The entire speaker runs off one amplifier. People are using these amps for planars and electrostatics.
Same pinout as uA741, 5534, OPA604 etc. You may have to fiddle with the compensation pin. MJE340/350 is available, and output transistors are fully complementary, MJ15015/16 still available.
The LM318 is still available, even in a PDIP package: https://www.digikey.com/en/products...fer-amps/687?s=N4IgTCBcDaIDIFkDMBGAHAGhAXQL5A
That said, a more modern replacement would probably be advisable.
A band I played with in the mid-late '70s used BGW for their PA system (not sure which one), and we never had any trouble with it.
They are not compatible without modifications. The LM318 is still a good opamp for its purpose.
Well, according to what I have found so far, this amp is favored over all of the rest of the pro amps of its time do to its sound quality, with many people still using them it high end systems to this day.
However, I also found out that all of the original parts are still available for the M-505, whereas the original output transistors may be hard to find for the BGW.
Both amps however are fully tested, and guarateed to work, with the BGW (15K input) selling at half the price of the Onkyo (100K input). I don't know which will perform better with my PS Audio IVH preamp.
However, I also found out that all of the original parts are still available for the M-505, whereas the original output transistors may be hard to find for the BGW.
Both amps however are fully tested, and guarateed to work, with the BGW (15K input) selling at half the price of the Onkyo (100K input). I don't know which will perform better with my PS Audio IVH preamp.
If they are that cheap, buy both and sell the one you don't want. Or keep it for a second system, or a spare.
With the small output cap on the PS Audio preamp, the Onkyo may have more low bass than the BGW.
With the small output cap on the PS Audio preamp, the Onkyo may have more low bass than the BGW.
rayma, did you see my other post stating that the manual for the IVH states thats its passive output impedance is "around" 1K?
There is absolutely nothing wrong with the LM318. If it works leave it alone. Maybe buy a few spares and leave them in a drawer somewhere for when they DO quit making DIP packages. In another 20 years you will NOT be able to get them.
MJ15015/6 are junk. If they ever die use MJ15003/4 or anything higher on the food chain. Even C5200N/A1943N retrofits will work and are superior ruggedness-wise.
MJ15015/6 are junk. If they ever die use MJ15003/4 or anything higher on the food chain. Even C5200N/A1943N retrofits will work and are superior ruggedness-wise.
Yes, it's an odd circuit with two halves in parallel, each with around 2k series resistor.
But if I recall, each half also has a series 1uF coupling capacitor. That is what rolls off the bass, not the resistors.
Yes, but because of the small output coupling capacitors.
They appear to be 1uF in the schematic, but they should be more like 10uF.
Even the 2k preamp output going to the 15k amp input, is still good enough.
They appear to be 1uF in the schematic, but they should be more like 10uF.
Even the 2k preamp output going to the 15k amp input, is still good enough.