Antonio J. wrote:

So I thought my tuner weren't properly adjusted. It has not been serviced nor recently aligned, I have no proficient technicians around who I depend to let them put their hands into the tuner. The damn thing always picked up Bidat's and CEC's noise. In my case the most noisy of the two is the CEC transport and only can get rid of the noise by switching off both devices. When the Bidat doesn't detect a potential input, like when switching off the CEC, then the noise gets worse. In my case not ferrite nor ERS sheets have been helpful at all. Only placing the digital parts very away (more than 1m) from the tuner is a bit helpful.

Peter, I do not know what is doing in with AM, I do not use it and all my experiments are in FM range. You might do the following: take FM antenna out of tuner and use instead a few cm of local wire. Defeat the noise causation on Sansui and run the tuner from I would say 95.0 to 101.0Meg. You will have a few stations and a lot of nasty air-noise that will be more or less homogenous. Then turn the Larvy 924 on and run the tuner across the range again. You will see some heavy MF signals and regions of complete exclusion of air-noise (that is interference too). Turning Lavry on and off will show up very indicative how much Lavry tosses out noise. Wight down the regions of max MF signal the come from Lavry. Put antenna back, turn Lavry off and tune to a station in the written regions. Attenuate the signal for Sansui for a given station. Listen the background noise – you shell have no hiss of any kind. Then tune the Larvy on. Listen the HF hiss that will be coming…

Sure the result might wary upon many conditions. In my case Larvy 924 and FM reception are not compatible. It does not bother me BTW too much as there is no need to run Lavry DA while I do recording. However, I need to run my A/D machines… That is why I put a lot of ferret in my Sansui… In fact I am contemplation to disengage the Pacific D/A section and use it only as A/D processor… Pacific is WAY quieter from tuner interference then Larvy 924 of 122. Perhaps if I turn all my recording to Rohde & Schwarz (that made at very different pro standards and actually was designed to work in very heavy noisy environment) then it would be less hassles but at this point I am hesitant to give the duty to the Schwarz as it is not ready yet to perform at its full bloom.

Dear Romy,

My tests showed 2 separate types of noise/interference being caused when TU-X1 & DA-924 were switched ON while the TU-X1 was set to OUTPUT FM: -

First noise/interference, the Sansui TU-X1 was passing an AM broadcast on VARIABLE OUTPUT FM and on FIXED FM OUTPUT at a number frequencies 87.0 - 87.8 MHz, 92.2 MHz, 95.9 MHz, etc.  I did some more investigations and found that the wire from an adapter (AC to 12V DC) to my AM antenna tuner was a source of this interference.  Moving the wire affected the interference.  So the cause of this interference was a combination of: -

~ DA-924 being switched ON;
~ TU-X1 tuned to the particular frequency or frequency range; and
~ AM antenna tuner adapter's wire being in a particular position too close to another cable (I will investigate further).

So the first problem could be solved by either turning the DA-924 OFF or shifting the wire.  I shifted the wire.  Note that I could affect the noise/interference by placing my hand on the DA-924 near the IEC connector when trying to switch it OFF.

Second noise/interference, the Sansuii TU-X1 was picking up noise of the DA-924 attempting to locate a digital source, i.e., AES1 -> AES2 -> IEC -> MUTE -> AES1 ... at 95.7 MHz through 96.0 MHz.  Shifting the wire makes no difference to the noise/interference.  Note that I could affect the noise/interference by placing my hand on the DA-924 near the IEC connector of the DA-924 when trying to switch it OFF.

I detected NO OTHER unexpected noise/interference in my tests.

The Lavry DA-924 and Sansui TU-X1 are on separate equipment legs/chains and only come together at inputs to the amplifier.  They also are on separate uninterruptible power supplies that are on separate legs of our wall supplies.  Also, amplifier has internal pre-amplifier section.

Leg/chain A.

Digital source #1 feeds the DD-2 processor.
DD-2 processor feeds the Lavry DA-924 (AES-1).

Digital source #2 feeds the Lavry DA-924 (AES-2).
Lavry DA-924 feeds analog output to the amplifier (inputs pair #1).
Amplifier feeds speaker arrays.

Leg/chain B.

AM tuner system (aerial, rotator and fine tuner) feeds the Sansui TU-X1.
FM tuner system (aerial array and rotator) feeds the Sansui TU-X1.
Sansui TU-X1 feeds analog output (OUTPUT-1 VARIABLE FM) to the amplifier (inputs pair #2).
Sansui TU-X1 feeds analog output (OUTPUT-2 VARIABLE AM) to the amplifier (inputs pair #3).
Sansui TU-X1 feeds analog output (OUTPUT-3 FIXED FM) to the amplifier (inputs pair #4).
Amplifier feeds speaker arrays.

Leg/chain C.

Microphones feed analog output to the Lavry 4496 (pre-amplifier + clock + ADC).
Lavry 4496 feeds digital output to the hard disc recorder.
Hard disc recorder (inbuilt DAC) feeds analog output to the amplifier (inputs pair #5).
Hard disc recorder (digital source #3) feeds digital output to backup DAC.
Backup DAC feeds analog output to the amplifier (inputs pair #6).
Amplifier feeds speaker arrays.

Thoughts:

1.  Lavry performs a power supply upgrade for DA-924 units marked as 'db technologies'.  Have you done that upgrade?  I wonder if that upgrade would help mask some of the noise/interference you are receiving.

2.  Does your Sansui TU-X1 have the AM section active or did you disconnect/remove it?  I assume that your Sansui TU-X1 has the AM section operational and that, as standard, the TU-X1 is supplying AM and FM output simultaneously.

3.  Do you have an external AM aerial attached to the Sansui TU-X1 or are you relying on the inbuilt AM aerial (which I found unusable in our location)?  In my case, I was able to use my powerful AM antenna system to clearly identify one of the noise sources as a very distant AM broadcast even though the amplifier was switched to amplify the Sansui TU-X1's OUTPUT-1 VARIABLE FM or the OUTPUT-3 FIXED FM.  Weird.

4.  Regardless of the above, there is still a source of noise/interference that the Lavry DA-924 generates on my system when it cycles looking for digital sources, i.e., AES1 -> AES2 -> IEC -> MUTE -> AES1 ... at 95.7 MHz through 96.0 MHz.

Romy the Cat wrote:

Hm, this is interesting. I my case nether neither CEC nor Bidat affect other of the tuners. Lavrys do but not Bidat. Try to put ferrite on ALL Sansui inputs: antenna, power cord, output cables. I have 3 bids on each leg of power cord, 4 bids on combined power wires, one bid on each combined analog output and 12 bids on the combined antenna cable on the cable between the input jack and the entrance to front end. My TU-1X do not acknowledge Bidat at all, ether the DAC is it locked of not. The caT

Peter,

It is obviously that in your installation Lavry and FM are much more isolated then in mine. In fact if your power amp breaks both ground and central wire then when you switch you playback to “Leg B” then digital in not in the picture at all. Even your recorder that pumps to the amp directly is off when your amps are in FM mode. 

peter foster wrote:

1.  Lavry performs a power supply upgrade for DA-924 units marked as 'db technologies'.  Have you done that upgrade?  I wonder if that upgrade would help mask some of the noise/interference you are receiving.

peter foster wrote:

2.  Does your Sansui TU-X1 have the AM section active or did you disconnect/remove it?  I assume that your Sansui TU-X1 has the AM section operational and that, as standard, the TU-X1 is supplying AM and FM output simultaneously.

My TU-X1 has AM section active but I do not use it. BTW, the TU-X1’s AM section is a truly Rolls-Roys -like according to my tuner guys and it shell yield a very high performance. I juts do not care about the AM programming I have in Boston.

peter foster wrote:

3.  Do you have an external AM aerial attached to the Sansui TU-X1 or are you relying on the inbuilt AM aerial (which I found unusable in our location)?  In my case, I was able to use my powerful AM antenna system to clearly identify one of the noise sources as a very distant AM broadcast even though the amplifier was switched to amplify the Sansui TU-X1's OUTPUT-1 VARIABLE FM or the OUTPUT-3 FIXED FM.  Weird.

So, you use AM section to identify the souse of interference? Interesting. The DAC it looks like tosses a lot of noise at wide bandwidth. I afraid that with AM region it might be different then in FM

Antonio J. wrote:

Thanks for the detailed ferrite setup in your system. I'll try it that way and see what happens, hopefully I can keep the digital rig on (which is almost a requirement to have decent sound when starting listening to CDs) while listening to FM.