9.1 Phono Hum and upgrade

[Punkuk]

I have a 9.1 but using the phono input is imposable due to the hum.
I don’t think it is a ground loop as I have:
Disconnected everything but the phono input
Turned off all other power in the house except the power circuit for the Hi Fi
Used an MIT Z-Isolator for the power supply
Ungrounded everything
Grounded the amp then the step up amp then the TT.
Added a ground loop isolator to the TV coax.
Tried shielded ICs
Tried shielded ACs.
I have spent hours trying to get rid of this hum

When I unplug the phono IC from the amp no hum if I connect an IC the hum returns
I tried connecting the other end of the IC to a tape , Video and CD deck all these units were unplugged (I did not send a signal) the same hum.
I have checked for a short in the phono input but it reads fine so I am left with????
I am using a MC cartridge with a step up amp this just makes the hum worse.
It is louder than the music.

As a second point how do I upgrade the 9.1 since I have had it I have never tried to upgrade, is there a web site with new firmware?
I called Integra but they said there are no upgrades available but I read on the web that this can be upgraded to a U2.
Thanks

[Azeke]

OK, I'll take a shot.

Is there a ground wire on the phono which can be directly connected to the ground on the receiver?

Just a quick thought,

Azeke

[Punkuk]

Hum Maybe Active ICs?

Yep tried that also from the step up to the TT, step up to the amp, tt to the amp.
Then amp, tt, step up tried every combination.
What I have found is that the only time is completely eliminated is if I plug it into my DVD (This is not a grounded unit).
Also I am using Black Mountain Pinnacle silvers if I use my signal cable copper it is also reduced.
Where can I get a braded sleeve as I will try to cover the ICs with some form of EMI filter?
I did just try a choke well three of them on different connections but no change.
I was seriously think active cable has anyone had any experience with this type of IC?

[alupats]

I suggest you try going with a "ground lift" by plugging your amp into a 3-to-2 prong adapter, you know the ones people use in older houses that have "two wire" outlets. Cut off the metal ring (that represents the midle ground wire) so it doesn't contact the face plate mounting screw when you plug it in. I used to play bass in a band, believe me probably every bass player out there has one or two of these adapters in his guitar case. You never know when you might need it. Actually there are different opinions as to why this works. The most believable is the bass amp is connected to a different leg of the incoming 220V line than the rest of the system.

[Punkuk]

Just gave up! and went with Copper Ics

Thanks for all the suggestions I have tried them all I ended up going with Signal Cable Analog Twos this has reduced the hum by 95% the sound quality has diminished as I found the silver to be a much better choice for the IC but I can live with what I have rather than what I had.
I am still going to experiment with different set ups and if I find a mind blowing revelation to the hum I will post it here.

[Burke Strickland]

I would expect the hum to be much worse with a step up amp plugged into the phono input, since you are then feeding a line level signal into the phono input, which is designed to accept a much lower level signal. Have you tried plugging the output from the step-up amp into a line level input on the 9.1 (virtually any other input than phono -- tape, CD, video) ?

Input Sensitivity and Impedance
PHONO: 2.5 mV, 50 kohms
Phono Overload: 110 mV RMS at 1 kHz, 0.5% T.H.D.

Have you compared the impedence and output voltage characteristics of your cartridge to the specs for the phono input? While the 9.1's phono input is designed to be compatible with a wide range of cartridges, yours might be one that is beyond its design limits, especially if your turntable has a phono preamp built in. (Typically a Thorens would not, but it is still worth asking.)

If it does have a phono preamp built in, then it would be giving you a line level output which would definately cause problems when plugged into the phono input, which would predictably be made even worse by using a step-up amp in between.

It might be interesting to try plugging the output of your turntable, with and without the step-up amp, into a line level input and see what happens. (Can't hurt anything -- it will just be very low in volume if the signal isn't strong enough.)

If the cartridge's impedence is a mismatch, then you may have to put a resistor in the circuit or replace the cartridge. Hopefully the step-up amp would take care of the impedence issue and inputting via a line level connection solves the input level issue.

Of course, if your cartridge's impedence and output are within the 9.1's specs, then there is still the possibility that your 9.1's phono input circuity is damaged or defective. But I'd try the other things before sending the unit in for repair.

[Punkuk]

I use a solo step up as I have a denon103r I just reaaly want that tube sound for my music but still need the 7-1 surround

[Punkuk]

tried without the step up not enough gain

[Burke Strickland]

So we've ruled out the poosibility that your turntable has a "stealth" phono preamp built in.

The DL103R is a low-output moving coil type cartridge. It has .27mv output and an impedance of 14 ohms.

It definately needs a step-up amp and the Solo is a good one. It is designed to input into a MM phono input, so the combo "should" work.

There's obviously something else going on here, but hard to pin down without knowing what is connected to what and how, throughout the system. Although you have installed a ground loop isolator for the TV coax feed, have you tried the phono setup with the TV coax completely disconnected? That's been the culprit in several installations I've helped troubleshoot, and not every isolation device works in all situations. Just a thought...

Burke

[Alaric]

Just read the owner's manual for the 9.1 and it specifically states the receiver's phono input is designed for a MM cartridge. I think you stated you are using a MC cartridge. Could this be the problem?

[Punkuk]

I use a solo step up amp.
It was the ICs I have to use shealed as opposed to unshealded sound suffers but anything is better than that awfull hum.