Ok I will try to make more photos. (Soon I will post a topic about the speaker system i am running, also old school alnico...
The output Z is moot; many power amps have high Zout.
The point here is that the higher-volt devices are driven "Common Base". On the old leaky devices, CB connection offers higher breakdown voltage. See Zoran's numbers:
Maximum Collector-Base Voltage |Vcb|: 90 V
Maximum Collector-Emitter Voltage |Vce|: 60 V
The low-volt transistor has a solid 10V across it, no Miller, no Early effect. The high volt transistor swings 30V to 60V (more?) but the low (dynamic) impedance at its Base improves the breakdown voltage from Vce to Vcb.
Intersting. I don't remember ever seeing Westrex in the USA, just Europe and of UK origin. I have seen some Vitaphone labeled horns that must have been W.E.
Is Zoran's amp a cinema amp? And from what decade - the 1960s? My Magnavox and Clairtone germanium amps are both early to mid 60s.
I think that it was mono block amps for rack console. For the cinema audio branch. They come with preamplifier units same brand, and 2way Westrex big box loudspeaker system with LF 15in unit 2080E and big HF unit 2390A. All alnico. I have these units and they are in perfect condition, 2390A running in current system...
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(Strange, additional monitor speakers was labeled as Westrex, but inside was fullrange University 8in alnico (beautiful), driven by Leak TL12+, P-P ultralinear, british amplifier unit. I restored this Lak amp too and it is very very good sounding amp.)
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(Strange, additional monitor speakers was labeled as Westrex, but inside was fullrange University 8in alnico (beautiful), driven by Leak TL12+, P-P ultralinear, british amplifier unit. I restored this Lak amp too and it is very very good sounding amp.)
I thought the last Westrex audio products were record cutting lathes and their power amplifiers. That is what I assumed Zoran's amp was.
The film-sound racket had been divorced from BellTel by US government pressure in the 1930s. Much of that work fell on All Technical Products, a servicing outfit, which soon shortened its name.
However Westrex was a name in record-lathes past the 1950s. Bell Labs had indisputable experience, and I guess the small market did not raise the political pressures of the huge theater market, and Scully was always an effective foil to Westrex lathes (and both doomed by the rise of Neumann).
How-ever.... I see now that the US divorce would not have affected use of the Westrex name in the UK, so business may have gone on.
BellTel, AT&T, Bell Labs were not pig-headed about building everything in-house. Much stuff was open-market bought and tested to spec. Some stuff was ahead of the curve and they "had" to do it themselves. But UK/EU Westrex had less support from US AT&T, now "only a telephone company", so the University/Leak components are a revelation but not a shock. You can't quibble with the quality of either. Also even AT&T was beginning to realize that "build for eternity" was not always the best path in an increasingly throw-away world. Big studios especially moved their best-room gear to their back room and then out to the curb, GAS-ing for sexier newer best-room gear every few years (or every good year).
And remember that for all that AT&T gave us, they "hid" the possibility of Magnetic Recording as long as possible.
The film-sound racket had been divorced from BellTel by US government pressure in the 1930s. Much of that work fell on All Technical Products, a servicing outfit, which soon shortened its name.
However Westrex was a name in record-lathes past the 1950s. Bell Labs had indisputable experience, and I guess the small market did not raise the political pressures of the huge theater market, and Scully was always an effective foil to Westrex lathes (and both doomed by the rise of Neumann).
How-ever.... I see now that the US divorce would not have affected use of the Westrex name in the UK, so business may have gone on.
BellTel, AT&T, Bell Labs were not pig-headed about building everything in-house. Much stuff was open-market bought and tested to spec. Some stuff was ahead of the curve and they "had" to do it themselves. But UK/EU Westrex had less support from US AT&T, now "only a telephone company", so the University/Leak components are a revelation but not a shock. You can't quibble with the quality of either. Also even AT&T was beginning to realize that "build for eternity" was not always the best path in an increasingly throw-away world. Big studios especially moved their best-room gear to their back room and then out to the curb, GAS-ing for sexier newer best-room gear every few years (or every good year).
And remember that for all that AT&T gave us, they "hid" the possibility of Magnetic Recording as long as possible.
Some of the preamp modules was
Westrex 32725 plug-in amplifiers
with wery good input and output signal balanced/SE transformers, and Bridged 600ohm, 11step/1db, T attenautor.
Westrex 32725 plug-in amplifiers
with wery good input and output signal balanced/SE transformers, and Bridged 600ohm, 11step/1db, T attenautor.
Attachments
That's quite a lovely find Zoran. What yo have represents and such an important part of audio history.
Thanks Pano.
That is because I like those parts and equipment. I like the sound. I will try to open other topics about the "system" I made based on all these "old" but beautiful parts.
(Wait for the RCA LC1A, Neumann DST cartridge...)
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I simply cant let go this beautiful Germanium piece of cake.
One more info about this amp, only output stage with transformer, has +17.5db cca gain (mesured with load).
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I am happy that some folks showed an interest at all in this topic... I see almost "old" members from 2003/4 ha ha... cheers.
I will post other datas I measured about parts, Westrex interstage transformers etc.
That is because I like those parts and equipment. I like the sound. I will try to open other topics about the "system" I made based on all these "old" but beautiful parts.
(Wait for the RCA LC1A, Neumann DST cartridge...)
.
I simply cant let go this beautiful Germanium piece of cake.
One more info about this amp, only output stage with transformer, has +17.5db cca gain (mesured with load).
.
I am happy that some folks showed an interest at all in this topic... I see almost "old" members from 2003/4 ha ha... cheers.
I will post other datas I measured about parts, Westrex interstage transformers etc.
By the way
Who (Brand), was making the interstage transformers for Westrex?
Western Electric, Triad..?
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(Power transformers in this amplifier have Logo label "Albion Transformers")
Who (Brand), was making the interstage transformers for Westrex?
Western Electric, Triad..?
.
(Power transformers in this amplifier have Logo label "Albion Transformers")
I found some photos of Interstage/phase splitter transformer. Also from Albion Transformers.
I measured (with simple RLC meter):
ALL COILS 1-2, 3-4, 5-6
2.1 ohm cca.
23-27 mHy cca.
...
Very low resistance of coil wires, slightly bigger wire, unfortunatly leads to also very low inductance of primary winding, but probably good coupling factor (I didnt measure) and lower capacitance?
Maybe is some air gap, I cant see.
I measured (with simple RLC meter):
ALL COILS 1-2, 3-4, 5-6
2.1 ohm cca.
23-27 mHy cca.
...
Very low resistance of coil wires, slightly bigger wire, unfortunatly leads to also very low inductance of primary winding, but probably good coupling factor (I didnt measure) and lower capacitance?
Maybe is some air gap, I cant see.
Attachments
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Interesting
I found some article mentioning Albion transformers
https://www.mercurymagnetics.com/pages/news/VGmag/VGMay11SHinterview.pdf
I found some article mentioning Albion transformers
https://www.mercurymagnetics.com/pages/news/VGmag/VGMay11SHinterview.pdf
New topic about my loudspeakers:
https://www.diyaudio.com/forums/mul...0a-iskra-ez1605-loudspeakers.html#post5607377
https://www.diyaudio.com/forums/mul...0a-iskra-ez1605-loudspeakers.html#post5607377
If You point to safety it is safer than usual line power wiring. By the standards wires have to be min. 6mm from metal chasses. It is not the case in contemporary equipment. These wires are original Westrex with excellent insulations. And they are away from ch. ground metal parts 2-3cm. 🙂
And offcourse that is absence of any heat in any of those wires. I checked with few days power on constantly...
Hi Kay
Thanks.
(It should be more precise, but I have only handy tools without stands...)
Cheers
Thanks.
(It should be more precise, but I have only handy tools without stands...)
Cheers
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