Discontinued moving coil transformers & head amplifiers
Older models of MC transformers are ...erm ... old MC transformers ...how can I put this, there has not been a great change in the quality of transformers over the last 60 years or more, there has been a gradual move towards better materials and a slight improvement in design and winding techniques but nothing similar to the series of revolutions that we have seen with electronics in general, so basically the only difference between a new MC transformer and an old model may be down to the effects of ageing and the fact that modern MC pickups generally have slightly different characteristics than they generally had a few decades back, thus mating an old transformer with a new pickup or the other way around may not result in a perfect match but close enough in most cases, and unlike electronics the effects of aging in transformers are not always on the minus side.All transformers and wound transducers suffer from magnetic build-up and other gradual changes that affect the characteristics of the units with the passage of time, mind you the effect is not always negative and for electric transformers it's nothing that will have a great effect on the performance but on audio transformers the effect will be noticeable over decades, this can often be rectified by rewinding or demagnetisation. Some manufacturers like for instance Ortofon will rewind old transformers for you and there are also independent workshops that will perform this work, make sure to find a workshop that has specialist knowledge of audio trannies, I have sent an audio transformer to a general transformer workshop and got back an unusable unit.
Still if it's only a is 10 or 25 years old unit you should not bother and if it is a transformer wound from silver wire the chances are that it will actually have improved with age, but be aware that some of the transformers on the market are 40 years old or more, we have actually seen Thordarson trannies from the 1920's advertised on Ebay as "almost new, little used", so do a little bit of research before acting.Apart from this the only change that have been seen for the last 40 years or so is the change from fixed impedance models to variable impedance models, most of the old fixed impedance models were sold as single transformers housed in a simple metal cans that hi-fi stores, radio outfitters and mixer manufacturers etc. then integrated into mixing decks, turntable bases or amplifiers and so on as either pick-up or microphone amplifier stages. Most modern transformers are generally pairs fitted into separate boxes however and a large portion of them offer variable impedance, it should be noted though that there is quite a difference between the sound of transformers, especially between a high quality one and a low quality item were you can hear the difference quite easily but it is often not as pronounced as between head amps or other pieces of active electronics.
As for head amplifiers you are well advised to stay away from anything much older than 15 - 25 years old or so, the advancements in op-amp technology have been so great that listening to a 25 year old model and a modern one side by side is a revealing experience, and makes you wonder why you never noticed all that noise before.
It was replaced in Oct. 1984 with the more upmarket C-17 model that was produced until the company stopped the manufacture of its entire phonographic line-up in 1989. Unlike the C7 the C17 actually offered some variability in gain and impedance and could thus be used with pickups that had different specifications to the models Accuphase itself was offering, it was also considered to be an excellent sounding unit in its day but was in turn considerably more expensive than the C7 model. Note that both units have switchable power supplies and can be used anywhere in the world.
Unlike the C-7 the signal path in the C-17 is almost entirely discrete and therefore is a considerably more refined sounding than its predecessor and in fact one of the few headamps from the 80´s that has stood the test of time, the Dual Mono design helps as well. However it should be taken into account that the second hand prices for the unit are also considerably higher than for the C-7, in 2011/12 they were routinely going for USD 1000 in the USA and in some cases even more in Asia and Europe.
The Accuphase C-7 technical specifications are; Frecuency responce: 5Hz ~ 100kHz. @ +0/-0.2dB. Inputs: 2x cinch + earthing terminal. Max input level: 35mV RMS. Outputs: 2x cinch. Gain: +26dB. Total harmonic distorion: Less than 0.002% at max input/20Hz ~ 20kHz. Signal to noise ratio: Better than 72dB @ 0.1mV input, A-weighted. Bypass: Yes. Size:10.2 x 6.1 x 35cm (Width x height x depth). Weight: 2.5 kg. Power requirements: 100, 117, 220 and 240V (Switchable). Power consumption: 5 watts.
The Accuphase C-17 technical specifications are; Frecuency responce: 20Hz ~ 20kHz. @ +0/-0.2dB. or 2Hz ~ 100kHz. @ +0/-3dB. Inputs: 2x cinch + earthing terminal. Max input level: 150mV @ 1kHz/+26dB and 76mV @ 1kHz/+32dB. Rated input level: 0.1mV @ +26dB or 0.05mV @ +32dB. Input impedance: 10, 30 or 100 ohms (Switchable) ohms. Outputs: 2x cinch. Output levels: 2mV. Output impedance: 50 ohms. Minimum load impedance: 10k ohms. Gain: 0dB, +26dB or 32dB (Switchable). Total harmonic distorion: Less than 0.005% at max output/20Hz ~ 20kHz. Signal to noise ratio: Better than 72dB @ +26dB gain or +66dB @ +32dB gain. Bypass: Yes. Size:19.4 x 14.2 x 37.1cm (Width x height x depth). Weight: 8.1 kg. Power requirements: 100, 117, 220 and 240V (Switchable). Power consumption: 30 watts. RRP: 190,000 ¥ in 1984.
Electro Sonic Laboratories (ESL)
Thorens - Restek
Uesugi Brothers (U*Bros)