line level transformers - Big v Little

[blackieNYC]

I have a nice big Edcor WS10k/10k.  The wound core of it is larger than an entire TM018.  I'm testing it between two pedals - a buffer on the front.  The frequency response, measured at the secondary, is the same! from 12K down to 40Hz, where the TM0 is down only .5dB.

The specs for the TM018 cite 300Hz to 3.5KHz.  The Edcor curve is flat from 20Hz to 20K. I'm using a Micronta true RMS voltmeter. Why are they performing the same on my bench? 

I'm looking for a ground isolator for a 2nd amplifier input.  this isolator will follow pedals and not the guitar. I expected the TM018 would need RG's isolated splitter active circuit to compete with this big chunk of iron, and maybe outperform it.  (It too is quite flat.)

[PRR]

Size is more about maximum bass level un-distorted, not how far down small-bass can go.

A microphone transformer smaller than my thumb can be flat to 20Hz. So can a Fisher output transformer half the size of my head. Difference? The peanut iron only carries 0.1V at 40Hz before it comes out bent. The big lump may carry 20 Watts at 40Hz clean, which at same impedance is like 62V.

What are you *driving* it with? The $2 transformers are rated for sorta-matched source and load. If you are driving with much-less than 10,000 Ohms, bass will be very extended.

[blackieNYC]

This would  be on the input of the second amp.  After a pedal of 1K output Z, let's say.  Like I said, I have it between two pedals now: 1K output Z -> 10K/10K transformer -> 1M input Z pedal. The Edcor is fine, but I don't know why the little xformer is doing just as well.

[wavley]

This would  be on the input of the second amp.  After a pedal of 1K output Z, let's say.  Like I said, I have it between two pedals now: 1K output Z -> 10K/10K transformer -> 1M input Z pedal. The Edcor is fine, but I don't know why the little xformer is doing just as well.

I went through this a few years ago screwing around with RG's Hum Free ABY, the little transformer does just fine with the low end of a regular guitar.  I play a lot of baritone guitar and Bass VI and I was getting some distortion on the low end of those, not like the good fattening you get from pushing a good small mic input transformer or the output transformer of a good mic pre, it was more abrupt and nasty, kind of like blocking distortion on the grid of the tube.  I played around with the circuit a bit and then I rebuilt it a little differently using the Edcors and problem solved.  Now I'm not saying that there isn't the possibility of some other non-linearity in the driver circuit that didn't agree with the Triad transformer I was using, but it didn't have the same problem with the larger transformers.  There was some discussion with RG a while back and he had some theories, but I don't think that we ever truly came to a resolution, it just required more time screwing around with a circuit that didn't fit my needs when I already had one that did solve my problem so I moved on to other things.

[blackieNYC]

I read that thread.
So I could go with the edcor AND the op amp driving it. Sounds like that's the best performance.
I was really hoping to go passive with the edcor. So it could live in a little box in the bottom of amp #2. 

[wavley]

I read that thread.
So I could go with the edcor AND the op amp driving it. Sounds like that's the best performance.
I was really hoping to go passive with the edcor. So it could live in a little box in the bottom of amp #2.

I recently got an EHX 2880 and it's always on buffers drive the edcors just fine.  Mine now live on the floor next to the amp, the junction boxes I put them in just aren't enough to shield them from the hum induced by my power transformer.  Works great, I was just playing Bass VI last night and deciding that I need a little less low end.

[blackieNYC]

The Edcor, w or w/o the buffer driving it, is prone to picking up hum?  I don't suppose the little ones are much better.
So you could not put it on top of the amp.  How happy are you with this now? Is the metal box, and a little distance from the amp, still give a little hum? 
This isn't sounding quite as solid a solution as I thought

Anyone else using ISO transformers to go to two amps? 
I did this for years with a ground lift plug- don't do that.  But what is the best way to go stereo in a club/studio environment? 
Is it better to just get a short n sturdy extension cord and make sure both amps are on the same circuit?  I don't think I've ever tried it.

[wavley]

The Edcor, w or w/o the buffer driving it, is prone to picking up hum?  I don't suppose the little ones are much better.
So you could not put it on top of the amp.  How happy are you with this now? Is the metal box, and a little distance from the amp, still give a little hum? 
This isn't sounding quite as solid a solution as I thought

Anyone else using ISO transformers to go to two amps? 
I did this for years with a ground lift plug- don't do that.  But what is the best way to go stereo in a club/studio environment? 
Is it better to just get a short n sturdy extension cord and make sure both amps are on the same circuit?  I don't think I've ever tried it.

The buffers in my 2880 drive it just fine so I didn't need my driver circuit anymore.  So I moved them to the amps and it keeps the buffered length longer.  I still have my drivers boxed up in case I need them, but I'm going to leave the transformers in their own boxes near/on/in the amps.

I have one amp that is really fussy about where I put the box with my transformer in it so I just leave it on the floor, but I could just as easily screw it inside the cab where it doesn't hum.  That amp lives in my studio and I hate getting behind it to unplug it so it lives on the floor.  The amp I was using until just recently on the other side of the room didn't care where I put the transformer.  I've been using two transformers for two amps for a number of years now, one of them has a phase switch so I can adjust for different amps.  Currently I have one amp that needs the transformer to not hum (and the phase switch) and one amp that actually hums less without the transformer that is my main rig.  That's why I like the transformers being in passive boxes that I just use when I need them instead of when they where built onto my pedalboard.  Ground loops are strange and changing one amp out for another can change the whole nature of the loop, every amp I own except my Harmony 525 needs to be transformer isolated from my pedalboard or it will loop with the board and other amp so it's always good for me to keep two around because I like to swap amps a lot when I'm recording.

[blackieNYC]

This is great guys, thanks.  I'm going to use the edcor.
One more question - I think I'll get the best performance with an active buffer, but from what you're telling me, maybe I don't need a buffer built in. Because I always have a pedal on, and the ones most likely to be last in the chain have an output Z of 1k. That's probably a fine buffer to get the most out of the edcor, no?
Definite phase reversal switch.

[wavley]

This is great guys, thanks.  I'm going to use the edcor.
One more question - I think I'll get the best performance with an active buffer, but from what you're telling me, maybe I don't need a buffer built in. Because I always have a pedal on, and the ones most likely to be last in the chain have an output Z of 1k. That's probably a fine buffer to get the most out of the edcor, no?
Definite phase reversal switch.

I seem to remember not liking my Memory Man w/ Hazarai driving the transformers and needing my driver buffers, but I had already moved the transformers to the amps at that point.  My Boomerang+ looper drives both transformers from a mono out just fine and my 2880 drives both transformers (when I need two) from it's stereo outs, the tube output buffer of my Peavey Valverb won't drive them without big loss in the lows, but the digital Ultraverb did great.  Until I end up with a looper that I like more than the 2880 it doesn't seem I'm going to have any problems driving them and having to put my buffers back on the board.

1k will probably be fine.  I have one more iso transformer in my rig, the signal goes up to my Space Echo and back down to the board.  I need something on the output of the Space Echo to break a loop, the discrete buffer in it worked fine, the op amp one I built into it works better.  The Space Echo is weird because it's output impedance changes depending on the setting of the output attenuator, so I built a buffer after the attenuator.  I also built an input buffer using the Mini-Booster as my inspiration to deal with it's miserably low input impedance.  Doesn't seem that I *really* need a bipolar power supply heavy duty buffer to drive them, although if sit down and REALLY listen and critique, my drivers and the Boomerang+, sound just a hair better, obviously not enough that I felt that I needed them on my board and I almost never move my rig anymore now that I have my own repair shop/studio where we can just have people come to us to play a show (I guess that's one advantage to living in a town with zero decent traditional venues) 

It seems that the Edcors are pretty ok with being driven by just about anything, I didn't try all of these things as much with the little Triads and TM018s because I wasn't getting the low end of my Bass VI or baritone guitars that I wanted even with dedicated drivers.

One note, I'm using the 15k:10k  PC series Edcors