Where to buy Mu Metal for SUT build.

[diceman]

After a long-time lash up using oodles of crocodile clits I'm now forced to finish off my part built SUT as I'm chamngin gcartridge so need teh other loading option on my Hashimotor HM-3 SUTs.

I started on the copper chassis years ago and bought the silver wire, switches and foo grade phono sockets but just needed the mu-metal and to get the chassis sides machined up. It sounded pretty good as is and hum was not terrible so I just lived with it as time has been very short over the last few years.

Does anybody know what type or where is best to source the mu-metal self adhesive lining material for the inside of the case? Do I need to line copper top & bottom as well?

I believe the appropriate wiring diagram is on here somewhere sop as to add the switch for the Hi/Lo gain and I plan on using a phono socket with added loading resistors if required (hence the 3 Phono holes).

Any help greatly appreciated.

 

[zeta4]

Try Magnetic Shields Ltd. They specialize in mu metal shielding cans/foils etc. The Hashimoto is already mounted in a mu metal can
within another ferrous metal can. Normally this is enough shielding but adding more certainly wont hurt. Ive got some 0.1mm mu metal foil
with an adhesive backing and it may have come from them but I cant find any shipping details. If you can get something like this I think it would work well as you dont need a thick foil as the transformer is already shielded by a thick one. Also your foil on the case will be some distance from the transformer.

 

[rabski]

Here's your switch connections. You may (will) want to experiment with the grounding, and a ground lift switch is a must. It's also worth messing around with connection or not connecting a separate ground wire, as assuming the phono case and turntable are both external ground, sometimes a ground wire to the SUT case can be noisier than connecting the SUT case to signal ground and not connecting a separate ground.

 

[dave]

crocodile clits

 

[rabski]

I missed that. Obviously someone else is using the same spellcheck as me

 

[diceman]

Thank you, I will phone the mu metal supplier once I’ve worked out quantity. I hadn’t found a uk based supplier so that’s a big help

Schematic helps a lot I’m not sure I understand the grounding options though.

 

[Jag]

Thank you, I will phone the mu metal supplier once I’ve worked out quantity. I hadn’t found a uk based supplier so that’s a big help

Schematic helps a lot I’m not sure I understand the grounding options though.

I bought some mu metal self adhesive type A4 sheets from the USA a few years ago so will have a look in case I have any spare you can have one free for postage cost. I can not promise but will have a look for definite next couple of days, after my house move it is a bit hectic here.

 

[rabski]

Thank you, I will phone the numbers metal supplier once I’ve worked out quantity.

Schematic helps a lot I’m not sure I understand the grounding options though.

It's down to the difference between earth, ground, and signal return and also down to the fact that 'earth' is not always at exactly the same zero voltage as would be ideal. The differences are minute and in a CD system, or between a preamp and power amp, it won't make any noise. Unfortunately, the signal from a cartridge is incredibly low, so there is the opportunity for ground loops to cause hum.

The ground pin on the Hashimotos is connected to the transformer cases and the internal shield, and this should be connected to the case of the SUT. You can/should add a grounding post to the case. Normally, you will leave the signal return separate, but add a switch to connect the signal return to the case (ground).

The connection (or not) between signal return and ground is where hum loops turn nasty. The two are usually connected (or referenced) in preamps or integrated amps, they are usually separated (but with a ground/lift switch) in phono stages, and they are frequently not connected in turntables, though can be in some arms.

You would normally run a separate ground wire from the turntable to the phono stage. Adding a step-up increases the complication, because if you run a separate ground wire to the phono stage, turntable and SUT case, it's an open invitation to cause a ground loop. Almost every situation is different, and the only real answer is to experiment. You'll find the combination that gives the lowest noisefloor.

 

[diceman]

I bought some mu metal self adhesive type A4 sheets from the USA a few years ago so will have a look in case I have any spare you can have one free for postage cost. I can not promise but will have a look for definite next couple of days, after my house move it is a bit hectic here.

I'd be more than happy to pay teh going rate, if you find it please let me know and thank you.

 

[MF 1000]

There is a shielding tape available on Amazon…Titan RF shielding tape

 

[diceman]

It's down to the difference between earth, ground, and signal return and also down to the fact that 'earth' is not always at exactly the same zero voltage as would be ideal. The differences are minute and in a CD system, or between a preamp and power amp, it won't make any noise. Unfortunately, the signal from a cartridge is incredibly low, so there is the opportunity for ground loops to cause hum.

The ground pin on the Hashimotos is connected to the transformer cases and the internal shield, and this should be connected to the case of the SUT. You can/should add a grounding post to the case. Normally, you will leave the signal return separate, but add a switch to connect the signal return to the case (ground).

The connection (or not) between signal return and ground is where hum loops turn nasty. The two are usually connected (or referenced) in preamps or integrated amps, they are usually separated (but with a ground/lift switch) in phono stages, and they are frequently not connected in turntables, though can be in some arms.

You would normally run a separate ground wire from the turntable to the phono stage. Adding a step-up increases the complication, because if you run a separate ground wire to the phono stage, turntable and SUT case, it's an open invitation to cause a ground loop. Almost every situation is different, and the only real answer is to experiment. You'll find the combination that gives the lowest noisefloor.

Perfect, thank you. It makes a lot more sense now I’ve read your response and reminded myself of the pin designations of the transformer - I hadn’t remembered there was an earth pin on the tx.

 

[MF 1000]

There is a shielding tape available on Amazon…Titan RF shielding tape

Just had some of the RF shielding tape delivered plus some Farady cloth …..my dearest will be making a sleeve to fit over my home brew digital interconnect to further shield the signal from RF etc.
I’ll post up a new thread on here with the idea & test plus any results etc