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Author Topic: Schoeps m221b transformer  (Read 272 times)

Online afterlifestudios

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Schoeps m221b transformer
« on: June 06, 2018, 10:54:03 am »
Most of the Schoeps m221's I've seen (including my own pair) employ an "A925" output transformer.  I've recently come across one containing an "A700" transformer. Does anyone have any info about the differences or the history on this topic?
Thanks in advance,
John

Online David Satz

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Re: Schoeps m221b transformer
« Reply #1 on: June 06, 2018, 06:27:42 pm »
The original M 221 (1955) used a transformer designated as T 43, while the M 221 A (1956) used the T 44/1. The change from the latter to the A 925 appears to have occurred in about 1958; documentation in July of that year (M 221 F = version with Sogie output connector, made specifically for the French radio) shows "old" and "new" amplifier schematics (SB 92 and SB 93) with these two transformer types respectively.

After that, the A 925 is still shown in M 221 parts lists dated 1961, 1962, and even as late as September, 1971--and I don't have any Schoeps schematics or parts lists that refer to any "A700" transformer at all. That certainly doesn't mean that it never existed; there are significant gaps in Schoeps' own documentation from that period, let alone my subset of it. But I just don't see any reference to it.

--While interviewing people at Schoeps about the history of the company, I was told that Schoeps themselves had wound the transformers for the M 221 series, assigned individual serial numbers to them (!), and tested them individually to find the ones with the lowest distortion (said to be largely a function of how accurately the core laminations could be aligned). But I don't know whether this statement applied only to the A 925 (for example), or whether it applied to the other transformer types used in the M 221 series.

--best regards
« Last Edit: June 08, 2018, 12:41:21 am by David Satz »

Online afterlifestudios

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Re: Schoeps m221b transformer
« Reply #2 on: June 07, 2018, 02:23:34 am »
Thank you David.  Great info.  Thanks for sharing.

Here's a pic of the a700 in the m221b...

John

Online afterlifestudios

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Re: Schoeps m221b transformer
« Reply #3 on: June 08, 2018, 01:47:30 am »
Update:  I wrote to Schoeps and got this reply within just a few hours...
    
Hello John

Earlier M221 had the A925, later models the A700. In case of a defect transformer it was replaced by the A700 for older models as well.  Their in-out ratio was the same, their impedance as well. So their diference had no influence on sound or other parameters.

Kind regards,



Offline Recording Engineer

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Re: Schoeps m221b transformer
« Reply #4 on: June 08, 2018, 03:01:30 am »
What are those impedances and the ratio anyhow?