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Vintage Audio (record players, hi-fi etc) Amplifiers, speakers, gramophones and other audio equipment. |
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14th Jun 2021, 9:25 am | #21 |
Dekatron
Join Date: Sep 2015
Location: Southwold, Suffolk, UK.
Posts: 8,336
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Re: Pye black box 1004 transistor background noise problem
That high-output Acos cartridge will overload VT1 and will give you a non-linear volume control operation until it distorts at the higher volume settings. You could use one of those cheapo Red Ceramic chinese stereo cartridges often mentioned on here. Bear in mind that your very rare Acos Stereo-Compaible GP91-3SC has a high intrinsic value and will easily sell for £35-00 or more.
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Edward. |
14th Jun 2021, 12:23 pm | #22 | |
Dekatron
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
Posts: 16,536
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Re: Pye black box 1004 transistor background noise problem
Quote:
The "loudness" effect would seem to be about an 8dB increase in relative bass at low volume from a simple simulation treating the cartridge as a voltage source in series with 800pF capacitor.
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14th Jun 2021, 3:42 pm | #23 |
Octode
Join Date: Oct 2019
Location: Stockport, Greater Manchester, UK.
Posts: 1,646
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Re: Pye black box 1004 transistor background noise problem
Thank you Graham
Edward, I did see your post in another thread about the cartridge, and for this reason I had purchased a banpa bp2ATC cartidge aka "one of the Chinese red ones". Mounting it will require some thought as it's a clip on, but it can be done, even if I 3d print a mounting clip myself. The other issue is the output which is around 200-300mv/3cm for the Chinese ceramic ie significantly lower than the ronette the BB was built with which as you know is around 200mv/1cm. I could replace the Acos with the Chinese ceramic I bought, but I wasn't sure whether I would need to build a small pre amp with a x3 gain to go with it, and a linear power supply from the voltage across the bulb. So when I tried the acos and it sounded good at normal playing volume, and for quite a bit more volume to spare, I thought I'd call it a day. The BB is not going anywhere and I could always revisit this at a later stage. Gabriel |
14th Jun 2021, 8:46 pm | #24 |
Dekatron
Join Date: Sep 2015
Location: Southwold, Suffolk, UK.
Posts: 8,336
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Re: Pye black box 1004 transistor background noise problem
You certainly should not need any kind of pre-amp, nor would I add, or advise, one.
There is sufficient sensitivity and gain through all the AF stages of the Pye's amplifier to allow the average 200/250mV Chinese Ceramic to perform with ease.
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Edward. |