Barcus-Berry Standard Pre-Amp Model 1330-1  [traced]

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Barcus-Berry Standard Pre-Amp Model 1330-1

Postby turbofeedus » 13 Sep 2019, 19:11

Hey all, picked up this preamp last week. Came to me with a pretty bad crackle/hiss. Haven't sorted that out yet, but I did up a schematic.
I verified the transistor pinouts and gain with a DCA55.
Diodes are 1N7xx, forward voltage is 0.78V.
Enjoy and feel free to ask questions.
More pics here.

bb1330-1-3.JPG

drawings.jpg

1330-1 schematic.jpg
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287m (15 Sep 2019, 09:25), karul (13 Sep 2019, 20:18), Manfred (13 Sep 2019, 23:37), modman (17 Sep 2019, 08:52)
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Re: Barcus-Berry Standard Pre-Amp Model 1330-1

Postby Axldeziak » 15 Sep 2019, 02:49

Are there any visible markings on the Bass pot inductor? (Is it painted over?) Measurement, perhaps?
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Re: Barcus-Berry Standard Pre-Amp Model 1330-1  [traced]

Postby turbofeedus » 15 Sep 2019, 17:07

Axldeziak wrote:Are there any visible markings on the Bass pot inductor? (Is it painted over?) Measurement, perhaps?


Unfortunately not, and as far as I know, measuring for inductance is complicated.
I'd probably just start with a 500mH like this, and go from there.

Updated schematic with a couple corrections.

1330-1 schematic.jpg
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Re: Barcus-Berry Standard Pre-Amp Model 1330-1

Postby Manfred » 15 Sep 2019, 23:21

Unfortunately not, and as far as I know, measuring for inductance is complicated.

Not realy using a LCR-meter.
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Re: Barcus-Berry Standard Pre-Amp Model 1330-1

Postby Axldeziak » 16 Sep 2019, 03:15

I may have found a few clues as to what the ITS30326 is. Seems the style of JFet, round, white on the sides with a black top was produced by Siliconix in the mid 70's and was known as the E series.
From there I was able to find mention of E230 Siliconix fets being used in early Barcus Berry amps. The model number was later changed to J230. Looking in a copy of the 1986 Siliconix FET Databook the J230 is listed alongside the J231, and J232 as being N-Channel "Audio and Sub-Audio Amplifiers."
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Re: Barcus-Berry Standard Pre-Amp Model 1330-1

Postby turbofeedus » 16 Sep 2019, 04:52

Manfred wrote:
Unfortunately not, and as far as I know, measuring for inductance is complicated.

Not realy using a LCR-meter.


Don't have one of those unfortunately.

Axldeziak wrote:I may have found a few clues as to what the ITS30326 is. Seems the style of JFet, round, white on the sides with a black top was produced by Siliconix in the mid 70's and was known as the E series.
From there I was able to find mention of E230 Siliconix fets being used in early Barcus Berry amps. The model number was later changed to J230. Looking in a copy of the 1986 Siliconix FET Databook the J230 is listed alongside the J231, and J232 as being N-Channel "Audio and Sub-Audio Amplifiers."


Nice, ultimately it doesn't matter much in this context. It's just being used as a buffer, so any modern NJFET should work ok; J113, 2N5484, etc.
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Re: Barcus-Berry Standard Pre-Amp Model 1330-1

Postby Manfred » 16 Sep 2019, 15:09

Don't have one of those unfortunately.

I see, perhaps there is repair shop in your area you can aks for measurement.
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