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Vintage Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players Open-reel tape recorders, cassette recorders, 8-track players etc. |
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6th Mar 2017, 3:58 pm | #21 |
Dekatron
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 13,454
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Re: How to bias Philips EL 3536 valve tape amp?
For measurements where the circuit voltage is high then switch the probe to X10.
Lawrence. |
6th Mar 2017, 4:12 pm | #22 |
Octode
Join Date: Mar 2006
Location: Lund, Sweden
Posts: 1,631
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Re: How to bias Philips EL 3536 valve tape amp?
Normally you would do that anyway to get the probe compensation circuit switched in. And especially in that position, it's not a problem to measure a couple of hundred volts with an oscilloscope.
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7th Mar 2017, 11:37 am | #23 |
Pentode
Join Date: Aug 2007
Location: London, UK.
Posts: 115
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Re: How to bias Philips EL 3536 valve tape amp?
Hi All
I've attached result pics from my CRO. I attached a 1kHz signal generator to the mic input, set it to PA and recorded the o/p across one speaker channel. Top is input bottom is output, (sine then square wave). It was quite a quiet signal going in. So mainly seems to be high freq boost? Or bass cut? I think the peak seemed to increase when I turned up the input. Now this is the mic i/p which uses an extra bit of circuitry to the tape head. Also I realised afterwards the tone control was set to full treble - not sure if this does anything on PA (the volume knob doesn't do anything on PA - it's the mic i/p that adjusts volume). Is there a better place to apply the signal eg on the tape head somewhere to get a better idea about playback? I wonder if should I record the signal on tape and play it back and test this. Cheers John |
7th Mar 2017, 6:54 pm | #24 |
Pentode
Join Date: Aug 2007
Location: London, UK.
Posts: 115
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Re: How to bias Philips EL 3536 valve tape amp?
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