Could I safely make out of two Levinson ML-3 stereo amplifiers two mono-amps by shorting the left and right speaker output binding posts and drive them with the two outputs from a Levinson ML-7preamp? (Two left connections two one amp and the right to the other) Or should I be worried about DC offset differences between the to shorten channels, gain differences and/or feedback problems?
Is it maybe saver to bridge them or would that induce other problems with something like instability/oscillation in the high frequencies of mt Acoustat model 2 + 2 electrostatics.
Thanks in advance for "feedback"
Is it maybe saver to bridge them or would that induce other problems with something like instability/oscillation in the high frequencies of mt Acoustat model 2 + 2 electrostatics.
Thanks in advance for "feedback"
Don't short!
No, you can't short the outputs together! Each amp would see the output impedance of the other, which in a high-damping factor amp is practically zero. I don't know enough about it to tell you what to do otherwise. Some amps can't be bridged. If I were you I would try to get the manufacturer to answer the question.
No, you can't short the outputs together! Each amp would see the output impedance of the other, which in a high-damping factor amp is practically zero. I don't know enough about it to tell you what to do otherwise. Some amps can't be bridged. If I were you I would try to get the manufacturer to answer the question.
DC offset can be trimmed internal and gain can be finetuned at the balancepots of the ML-7. I'm mostly worried about the feedback I mean that the feedback circuits from the paralled channels are going to errorcorrecting eachother.Nelson Pass said:
The only statement I can find about the use of feedback with this amp that large amounts of feedback are unneccesary due to the use of selected discrete components, for what is worth. In a German publication from september 1980 ("Hifi Exklusiv Nr. 9) a pair of Threshold Stasis 1 is compared with a ML-3 were the Thresholds are designated as the NFB (globally) type of amp.
Bridging would be an alternative (easier to manage when I had a balanced output at the ML-7A) but as said I'm worried about the low impedence at high frequencies.
The No. serie of Levinson have allready balanced inputs and only the ML-2 had as only member from the ML (MLAS) serie XLR's so it was possible to bridge two ML-2 for 100 Watts instaed of 25 Watts at 8 Ohms. The Threshold S/1000 was also a bridged amplifier as I recall and John Soderbergh had his reservations about the stability with electrostatic loudspeakers. A pair of S/1000 Series II I had was converted to SA/1 so was converted from a bridged to a massive parallel configuration.
So I think that amps with no global feedback circuit that calls upon the predriverstage to correct errors at the output stage like Thresholds and Rowlands are maybe saver to convert in a mono parallel configuration then Levinson's and/or maybe Krell's from that era that use more feedback.
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