high impedance isolator

[ecc83]

I was sorting out some transformers I had for a chap on another forum and wondered how one of them might sound in the circuit of an electric guitar feeding my MOTU M4.
The transformer was an OEP Z3002E a '10k +10k' input line bridging transformer and I simply wired jacks to each winding and plugged one into son's Mex Strat and the other into the M4. The guitar was 'floating' i.e. not grounded at all but this did not seem to worsen hum pickup, you could of course make provision to ground the guitar if you so wished, the traff giving 1kV isolation from the rest of the kit.

I have sent the clips to my son in France for him to hear and comment (many of you will know my hearing is FAR from good!) but, busy chap he be, no reply so far. Anyone here have an opinion?

I did not expect the transformer to work anything like as well as it did. I did try a 'low z' one in the circuit (OEP 262A6) and that, as I expected, all but shorted out the guitar signal. Might there be a market for such a box?

Dave.

 

[TalismanRich]

The transformer setup seemed to increase the upper frequencies of the guitar. It wasn't a drastic difference, but I could tell that the "no-tranff" sample was a bit rolled off, somewhat like you would get if you dropped a tone control a couple of numbers.

I didn't hear any obvious hum. What problem are you trying to address with this device?

 

[ecc83]

The transformer setup seemed to increase the upper frequencies of the guitar. It wasn't a drastic difference, but I could tell that the "no-tranff" sample was a bit rolled off, somewhat like you would get if you dropped a tone control a couple of numbers.

I didn't hear any obvious hum. What problem are you trying to address with this device?

No problem Rich. I had the transformers ready to send to a chap on the SoS forum as he wanted to make an isolator and since I had all the bits, traffs, jacks geetar, solder iron all handy I thought I would rig the lot quickly for interest. Many years ago I had tried a "600 Ohm" transformer to isolate a passive guitar and it gave next to no output, even into a high Z, 1meg amp.

We do not hear tales of guitarists being electrocuted these days thankfully. Any musician gigging around the country who does NOT have an RCCD feeding his kit AND a socket tester needs his/her head testing but a Z3000E in a tin could provide 'belt & braces'?

So, there is some difference introduced by the transformer but I venture to suggest it could be lived with if the need arose?

Further thought: Since you detected a small HF lift that could be corrected with a "Zobel Network" (series CR) across the secondary, probably an out of band transformer resonance but since the C R values would depend upon the exact parameters of the load AND the cable capacitance, best left to tone adjustment and Mk One lugs?

Dave.

 

[TalismanRich]

The tone change wasn't anything that a tiny twist of a tone control wouldn't fix. It would probably feel slightly different between a humbucker vs the strat. Guitar pickups can be sensitive to the loading. I noticed a change between plugging in a guitar straight into an amp vs using a buffered pedal board. My guitars into my Tascam interface sound completely different than when I use my Joyo wireless.

As for getting electrocuted today... darn near impossible if you use a wireless. I guess you can always get hit by lightning! Amps are all grounded outlets these days. It's not like the 60s where we had plugs that didn't have a set ground. Back in the day, I got a few shocks hitting a PA mic and my guitar at the same time.

 

[ecc83]

"As for getting electrocuted today... darn near impossible if you use a wireless. I guess you can always get hit by lightning! Amps are all grounded outlets these days. It's not like the 60s where we had plugs that didn't have a set ground. Back in the day, I got a few shocks hitting a PA mic and my guitar at the same time"

Oh I quite agree Rich. The important thing though about using the Z traff is that it allows the guitarist to be "earth free". Therefore even if a mic/mic stand became live* he would be relatively safe (feel a 'tingle' I am betting)

The unexpected thing about this to me at least, is the lack of impact it has had on the guitar's sound or, most importantly, hum level. I am just a bit miffed that this discovery has come about 40 years too late!

*Which I thinks is how it killed one poor guy?

Dave.

 

[TalismanRich]

This got me about as "earth free" as I could get. Our bassist was getting some serious AM radio pickup until he tried one. It cleared that right up. It doesn't stop induced hum like in a single coil Tele, but any grounding issues are definitely fixed.

The added advantage is that I can NEVER EVER step on my cord and pull the jack out of the guitar! (EMBARRASSING!)

 

[ecc83]

This got me about as "earth free" as I could get. Our bassist was getting some serious AM radio pickup until he tried one. It cleared that right up. It doesn't stop induced hum like in a single coil Tele, but any grounding issues are definitely fixed.

View attachment 152264

The added advantage is that I can NEVER EVER step on my cord and pull the jack out of the guitar! (EMBARRASSING!)

Looks good, I shall investigate and suggest one to my son who plays bass for a quartet, drums,guitar, bass, flute in France. Cables are always a bit of an issue. Does the Joyo work well for full range guitar and is latency low?

Dave.

 

[Papanate]

No problem Rich. I had the transformers ready to send to a chap on the SoS forum as he wanted to make an isolator and since I had all the bits, traffs, jacks geetar, solder iron all handy I thought I would rig the lot quickly for interest. Many years ago I had tried a "600 Ohm" transformer to isolate a passive guitar and it gave next to no output, even into a high Z, 1meg amp.

We do not hear tales of guitarists being electrocuted these days thankfully. Any musician gigging around the country who does NOT have an RCCD feeding his kit AND a socket tester needs his/her head testing but a Z3000E in a tin could provide 'belt & braces'?

So, there is some difference introduced by the transformer but I venture to suggest it could be lived with if the need arose?

Further thought: Since you detected a small HF lift that could be corrected with a "Zobel Network" (series CR) across the secondary, probably an out of band transformer resonance but since the C R values would depend upon the exact parameters of the load AND the cable capacitance, best left to tone adjustment and Mk One lugs?

Could you explain what it is that your setup fixes? I don’t see the purpose (maybe I’m dumb too!).

 

[ecc83]

Could you explain what it is that your setup fixes? I don’t see the purpose (maybe I’m dumb too!).

(sigh!) it fixes nothing! I never intended it to. I had the bits and tools out ready to pack the transformers off to a chap when the muse struck me! "I wonder if that 10k traff will work with a passive Strat"? It did.
Then I de soldered everything and sent off the transformers.

Jusfort the info might be interesting to someone is all.

Dave.

 

[TalismanRich]

Joyo claims 5ms latency. I don't have any issue with feel.

The only bugaboo that I've heard was using very high output pickups. Apparently too much voltage can cause overloading. I have Seth Lovers, AlnicoPro IIs, Strat, Tele and Lollar P90s and none of them overload it with volume full up and me strumming hard. I would say that EMGs would be a problem.