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Another AU-919

BLAH BLAH said:
Why not use a phono pre-amp with the 919...?!?
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Unlike a phono (head) pre-amp, the step-up transformer (Audio Technica MK10T) doesn't need an electrical supply and it was designed specifically for the Signet MK111 cartridge.

Dispensing with the transformer and feeding the signal into the MC input will help keep cable losses to a minimum as well as reducing the number of electrical connections. The transformer needed to be located close to the amplifier but positioned/orientated so as to avoid any possibility of hum induced by magnetic fields, so that's another little issue side-stepped if the MC input is now usable.
 
Protection PCB complete, resistor changes complete.

Reassembly and settings went well, front panel and all controls fitted, but none of the internal covers on yet, now listening to a CD that I know very well. :music:
 
Trying out all the inputs - now using Phono 1 MM :rockon:

I can hear it 'settling down' I think, older components getting used to their new friends. :banana:
 
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EW (Glenn) was able to calculate the exact resistors needed to get the loading right for my MC/cartridge input. It took 68 Kohm resistors in R39 & R40 to get the 47Kohm input that my Low-output Grado needed. Keep this in mind before sending the 919 back!
 
Which model of Grado is it?

As I understand the matter, low-output moving coil cartridges typically need to see an input impedance between 80 to 500 (ohms, not kilo ohms), though some specify lower or higher.

Vinylengine lists a large number of Grados needing to see 47K but all but one of them are Moving Iron type. The sole Moving Coil specified to need an input impedance of 47K is the XR Mk1, but this seems to date back to 1963. Another, the Mono from 1957, calls for 5K and the Laboratory (from 1963) needs 10-100 ohms (with its output impedance shown as 700 ohms)

As a novice, I rely on finding reliable sources of information, mainly on the internet. One of these sources is http://www.rothwellaudioproducts.co.uk/html/mc_step-up_transformers_explai.html. At the bottom of the webpage they list 40 or 45 MC cartridges together with their own recommended loading . The list doesn't include any Grado but there are a couple of other makes/models for which they recommend up to 47K. This high loading is clearly an exception to the norm, and I have no doubt whatsoever that the Signet would perform very poorly with anything like that.
 
I'm not saying that any MC cartridge needs a 47kohm load (except for the high output type). I'm saying that whatever your cartridge may need can be calculated to know what resistors to put in there. Better to get it right before sending it back. (By the way,...All grado's need 47kohms).
 
ghamilton, I have been reliably informed that 10 times the cartridge impedance will get the job done. David's cartridge has an 18 ohm impedance - hence 180 ohms was selected. Add to that elsewhere the cartridge is said to work best anywhere from 50-500 ohms impedance - hence 180 ohms fitted this too.

Also, don't you think myself, and the amp & cartridge owner have investigated this thoroughly? - I consulted EW and others along the way incidentally.
 
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Ok, perhaps I was assuming a bit too much for you to know how very important getting the MC input on the AU-919 working with the owner's specific MC cartridge, the cartridge is not well known and is somewhat unusual.

David and I have a 4 page conversation going on in the background about this specific issue.
 
Learn something new in every thread. Never having the luxury of an MC cartridge I always wondered why a few of my collection pieces have adjustable mc load controls, now I know.
-Lee
 
You're not alone, Lee.

Having learned back in 1980 of the benefits of Moving Coil, confirmed by further study in recent times, I'm surprised how many hi-fi experts and afficionados seem not to have experienced this advance.

Prior to the Signet, I had a Shure V15(?) MM and an Ortofon MM (different arm and turntable but all high quality) and I still recall the huge improvement in detail and 'musicality' that came with the Moving Coil cartridge. Other factors could have played a bit part, but not the full part.
 
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Incidentally, John, and with apologies for drifting off topic...

Was your 'you know the controversies' comment in post 113 in reference to the 'new speakers need 100/200 hours break in' argument that keeps cropping up?

I've read a lot of arguments for and against and, whilst I haven't any direct experience, the 'engineer' in me says that the only benefit of a lengthy break-in is in giving the owner's ears time to adjust to the different nuances of the sound that's reaching them.

An hour or so's loosening-up run might be helpful, but I'd say that anything more is a waste. I'm sure the manufacturers don't run their speakers for 100 or 200 hours at each and every stage of development so as to 'bed them in' before carrying out listening or measuring tests.

Back to the topic...
 
Multimode said:
Was your 'you know the controversies' comment in post 113 in reference to the 'new speakers need 100/200 hours break in' argument that keeps cropping up?
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No, actually it was the old chestnut 'do new capacitors require break in' - I'd best not say any more than that :D
Multimode said:
An hour or so's loosening-up run might be helpful, but I'd say that anything more is a waste.
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This :thumbsup:
 
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