posted 10 July 1999 04:25 PM         

It seemed to me that the 3-way connector he used would put in parallel three pairs of wires:

the output of the sustain box
the input of the tuner
the input of his volume pedal

so if there is a short (R=0, hence V=0) across one pair, there is a short across all. I think this would drain the batteries on the buffer amp pretty quickly, and v=0 means no signal.

Any impedance of the input of his tuner is paralleled with the pedal, which could change his sound.

Let me summarize what has been said here , then maybe mention the concerns. First of all I think everyone has good inputs(no pun intended) and reasonable concerns and Ernest seems to have some good technical points. In a nutshell we want to get the full frequency spectrum available from our steel to an amp input without rolling off the spectrum unless we choose to roll it off by adjusting someones impedance matching network that is between the guitar and amp or just turn the treble down on our mixer or amp etc. The load that our precious guitar pickup sees is everything that hangs on the other end of the cable. In this case, the total load for the pickup is the impedance offered at INPUT of our volume pedal WITH ALL the loads hanging on the outputs of the pedal. In this case it sounds unfortunately that the pot in the volume pedal will control not only what goes to the amp but also what would go to a tuner had you run output 2 to a tuner. The tuner load is in parallel with the capacitance of the cable which is hooked up to your main amp at the other end of cable #1 . If the input impedance of the tuner is infinite then it wont roll it off or rob signal power BUT its not infinite . Lets say its 50K and lets say your amp input is 50K . That means that the great high impedance of your amp has been pulled down to 25K and the cable capacitance will roll off the frequency. Lets just say if you did this arithmetic: 1 divided by the quantity (impedance in ohms times the cable and tuner input capacitance in farads) this would tell you where you will start rolling the high end (what Ernest said).
Also if you paralleled the input jack at least you could tune in silence leaving the two outputs available to drive stereo or two amps etc.

What us steelers need is a way to buffer auxilary outputs like this when they hang on the input side of our pedal so as not to rolloff our frequency range and so as not to cause impedance mismatch between source(guitar pickup) and critical load(main amp in). Hanging capacitance on any high impedance will quickly roll off the highs. If you turn your treble down half way , you may be able to recover.
Use a tuner with the highest possible input impedance , lowest capacitance, and dont agrevate the problem with the capacitance of long cable to the tuner :--) .

An opamp makes a pretty good buffer for auxilary loads like this like to a tuner.

Having a high quality active device , Keith's unit etc., inbetween is a great idea to sort out all of this. Maybe some circuit knobs to adjust the match and frequency response and buffered outputs to auxilary line outs like to a tuner or headphone monitor etc. Buffer amps will MASK the effects of auxiliary loads on the output side of the buffers.

Heres a tidbit: you will get maximum power if your source impedance is a conjugate of the load impedance ( in a way like source and load impedances are the same except you need inductance to tune out capacitance etc). If you have a resistive mismatch then all you lose is power so you need to preamplify to stay the same, there is no freq rolloff. If there is reactance like capacitance or inductance then you need a matching network (extra knobs on a magic little box) to not have frequency response problems.

To complicate the issue I'm sure there are a variety of impedances associated with all the pickups out there. The point is find the combination that SOUNDS good to you and your peers and then dont change your setup. In my case, I would make sure my wife likes it :--)

Using a coax Y adapter will just parallel the coax connection that it plugs into. There is no isolation between the two loads that you hook up to it. The direction you care about is how does the tuner affect the main amp input response. Here would be a bad situation. Lets say you had an amp with 50K input impedance and a tuner with 5K input impedance. Not only would you wonder where your signal to noise ratio went but you would also wonder where your high end went if you have much capacitance in this hookup.

Also if you bridge off before the pot in your pedal the ufortunate thing is that the frequency response will be more affected by what volume you have rocked your pedal to. Reason is the capacitance of the tuner and cable bridges a resistive load which is not constant. So if you ever try such a thing make sure its acceptable at all volume levels you would use.

Sorry this is so long but I guess it was a reply to all replys. Now for this you must all send me a spare #3 G# string for my E9 neck. PPOOIINNGG .... JUST KIDDING.

posted 10 July 1999 10:23 PM         

Am I running any risk to any of my equipment by hooking things up this way?

posted 10 July 1999 11:08 PM         

The first thing I noticed was that a good portion of the high frequencies had disappeared. I had to ootch up the highs to about 1 on both amps to get close to the same tone I had before, with the DS unit. However, the tone was still a bit muddy. (By the way, ootch is a technical term for the electronically challanged, like me.)

Next, I unplugged the tuner from the splitter. BIG improvement in tone. A very noticable improvement in tone. Still not as good as it was with the DS unit, but a definite improvement. By plugging the tuner back into the splitter, it went back to a very muddy sound.

So, I would have to say the Hilton Digital Sustain unit is what is making this setup work. And I have to say, although my Mullen sounds wonderful, it just gets wonderfuller with the Digital Sustain unit. (Wonderfuller is not a technical term. I just made it up. )

posted 11 July 1999 09:17 AM         

But it doesn't solve Doug's original problem. I have to switch my amp to standby while I tune if I don't want to annoy bystanders.

Doug, if you just add a second input jack it will work (bridge both hot and ground, by the way), but it will affect your tone a little bit. You'll bleed off some highs. Also if the tuner doesn't have a very high input impedance, it will throw off the taper of your pedal. Both of these effects are small but noticable to the discerning ear.

It seems to me that the buffer curcuitry from the Goodrich 10k could be applied before a volume pedal. That would be like a Matchbox with two outputs. One output would go to your pedal, and the other to your tuner.

A simpler approach would be an A-B box, though. This is a passive electronics project. Make a little box that will plug into your guitar with two outputs and a switch.

Simpler yet: add a second output jack and a switch to your guitar. Flip the switch when you want to tune. (hmmmm... I might just do that!)

posted 11 July 1999 09:41 AM         

My rack contains a Korg DT1 tuner (older) and an MPX100, in that order. I run straight from guitar to Korg-Lexicon, to volume pedal, to amp. In this fashion the tuner is always receiving unaltered signal from the guitar, and to tune in silence I simply back off the volume pedal.

The Korg has a mute button additionally, though not necessary if the tuner is inline before the pedal.

I was running my rack in the effects loop of my Evans, but the signal from the loop was not enough to effectively excite the tuner, and the output of the Lex was distorted. Then, as a last resort only, I read the Lexicon manual (!) which suggested the effects path I am currently using.

Would a Matchbox or similar buffer amp help my sound? Or would I not notice?

Oh, I'm playing a '65 Emmons wraparound with 15k ohm pickups that have more highs than anyone would possibly want. When using my Evans, the treble control is set to 1 or 1.5. My Nashville 400 has distinctly less high end and for that reason I've been playing it more lately. I'm going to put a BW 1502 in the Evans to see if I can cut the highs mechanically. As an experiment, I swapped the Eclipse from the Evans with the BW from the Peavey and got a little better response from the Evans in terms of balanced highs. The Evans might like a 1502, which is a bass speaker. Rick Price has this setup in his Evans and likes it a lot. But I think the Evans likes pickups in the 18k-20k range more than the 14k-15k types. Just MHO.

posted 12 July 1999 10:58 PM         

I think I must have started this in an earlier thread where I described how to modify a Goodrich pedal to convert the secondary output to a tuner thru connection. If I didn't state the necessity of a preamp drive, I should have.

Another advantage of the pre-volume connection to the tuner is that you don't route the signal through the tuner using the mute function. This adds more connectors and cables for the signal to go through and reducing the reliability of your setup. If you have a loose cable with the pre-volume (not thru the tuner) setup it will not affect your performance. You may not get a reading on your tuner but you can still play.

As I mentioned in that earlier thread, I don't see how anyone can make it through a live performance without quick tuning setups. I have played venues where AC systems chill my neck and "boom" 20,000 watts of stage lighting comes on and within minutes I am sweating and raising my string and neck temperature as much as 10 deg C. Tempered tuning scales and modern tuners like the Korg are wonderful things. If the temperature never changed, I could probably go all night without tuning. I never seem to experience that stable environment.

If you need quick tuning setups, it is not a challenge. Preamps with low output impedances are vital to this function.

posted 12 July 1999 11:29 PM         

Another issue with tuner connections that I failed to mention is hum. Often the Korg rack mount tuners have insufficient magnetic shielding with their internal transformer. The transformer shield is good enough for there internal circuits, but there is often enough primary winding flux leakage to induce a hum. A simple ground lift adapter on the Korg line cord can fix this. Everybody hates wall warts (transformer DC power supplies that plug in the wall) but Korg may have eliminated this problem and spent less money on a UL approval. I can't complain, they make a great tuner.

Nice inputs from everyone. I think this forum thing is gonna catch on.