Alix and a buffer

[rschultz]

Hi,

Been using an Alix for a while now with Barbera passive pickups. I've realized that I need a buffer as my first pedal, without it can really sound thin. This is fairly common with passive pickups. But if Alix is first, it doesn't seem to buffer the sound like other buffered pedals which surprises me. Changing the impedance doesn't affect the sound.

Anyone else experienced this or know if/how Alix is buffered?

[ljguitar]

Originally Posted by rschultz

Hi,

Been using an Alix for a while now with Barbera passive pickups. I've realized that I need a buffer as my first pedal, without it can really sound thin. This is fairly common with passive pickups. But if Alix is first, it doesn't seem to buffer the sound like other buffered pedals which surprises me. Changing the impedance doesn't affect the sound.

Anyone else experienced this or know if/how Alix is buffered?

Hi rs…
Have you talked with Grace? They hand build their wonderful equipment, and are quite knowledge (and are known for great service). You see their gear ending up on professional rigs all the time (pro as in full time touring top shelf pros).

I'd start there…I bet they know.

[Rudy4]

Originally Posted by rschultz

Hi,

Been using an Alix for a while now with Barbera passive pickups. I've realized that I need a buffer as my first pedal, without it can really sound thin. This is fairly common with passive pickups. But if Alix is first, it doesn't seem to buffer the sound like other buffered pedals which surprises me. Changing the impedance doesn't affect the sound.

Anyone else experienced this or know if/how Alix is buffered?

This from Grace Alix manual:

"The instrument input has a 3 position impedance switch to ensure your pickup system sounds its very best.
Instrument Input: HI: 10MΩ / MED: 1MΩ / LOW: 330kΩ"

Sounds like it offers as much buffering as you'll find.

[rschultz]

Originally Posted by Rudy4

This from Grace Alix manual:

"The instrument input has a 3 position impedance switch to ensure your pickup system sounds its very best.
Instrument Input: HI: 10MΩ / MED: 1MΩ / LOW: 330kΩ"

Sounds like it offers as much buffering as you'll find.

Impedance... is not a buffer.

[Rudy4]

Originally Posted by rschultz

Impedance... is not a buffer.

What do you think impedance matching is?

[sdelsolray]

Impedance “matching" and impedance “bridging” are two different things.

Impedance matching involves identical impedances at each end of a connection, e.g., 75 Ohm for work clock connections, 110 Ohm for AES digital connections, and 600 Ohm for early analog transmissions).

Impedance bridging occurs when a low impedance source feeds a much higher impedance, e.g., passive pickups to a preamp.

[lkingston]

I don’t have that preamp but it is one of the major players. I would be quite certain that the high impedance setting also included whatever preamping and buffering was needed.

[rschultz]

Originally Posted by lkingston

I don’t have that preamp but it is one of the major players. I would be quite certain that the high impedance setting also included whatever preamping and buffering was needed.

Yes I tend to agree... any effect pedal that is ON is in essence providing an active buffer/gain of some sort.

[rschultz]

Originally Posted by Rudy4

What do you think impedance matching is?

True bypass pedals have an input and output impedance.
Buffered pedals also have an input and output impedance.

The difference is that buffered pedals are actively applying some amount of fixed DC gain via an op amp, elevating the AC audio signal to make it resist noise or transmission loss etc.

You can have passive impedance matching (aka true bypass).

[lkingston]

If you use a buffer pedal, you will find yourself at the mercy of however well that buffer pedal handles the high impedance passive pickup. The buffer pedal will lock whatever that sound is in then pass it on the the Alix. I’m not sure you want that.

As I read the first post, my understanding is the problem is a thin sound from the Alix not handling the impedance of the passive pickup properly. Have you tried all three settings? It seems strange to me if that doesn’t fix the thin sound problem.

[rschultz]

Originally Posted by lkingston

If you use a buffer pedal, you will find yourself at the mercy of however well that buffer pedal handles the high impedance passive pickup. The buffer pedal will lock whatever that sound is in then pass it on the the Alix. I’m not sure you want that.

As I read the first post, my understanding is the problem is a thin sound from the Alix not handling the impedance of the passive pickup properly. Have you tried all three settings? It seems strange to me if that doesn’t fix the thin sound problem.

Yes I tried all 3 impedance settings... no noticeable difference.

[rschultz]

I talked to tech support at Grace Designs. He confirmed that obviously the Alix is buffered and recommended the high 10M impedance setting. As for why it sounds different with or without a buffer before it, he suggested the sound might be colored from the buffer.

I have tried 2 buffered pedals before Alix: Becos CompIQ compressor and a Klone overdrive with the gain at zero. The Klone is buffered bypass so it works on or off. Both sound the same to me, much better than going directly into the Alix. He suggested trying either pedal in the FX loop.

[rschultz]

Buffers are generally short for what the electronics world would call a Unity-gain buffer. Here's a good article explaining this:

https://www.learningaboutelectronics...ty-gain-buffer

One of the pedals I've used as a buffer is a Klon clone, or what PedalPCB refers to as Kliche buffer:



When pins 1 and 2 are connected without a resistor, it's unity gain. Otherwise gain is applied through a ratio of resistors around the op amp.

So as someone else pointed out, a buffer is trying to change the impedance from high to low without changing the overall signal level.

[rschultz]

I've been completely off base here. Just spent an hour or so:
Guitar straight into FRFR
Guitar straight into Alix, then FRFR
Guitar into 2 different buffered bypass pedals, then Alix, FRFR
Etc.

The Alix is fine, and it sounds generally similar (flat EQ) to direct into FRFR. Both buffered pedals I tried severely color the sound by cutting highs and boosting lows... IF they are first in the chain. But if they are placed elsewhere after Alix, they are great.

So there definitely is something about impedance mismatching and passive pickups. My Barbera Soloist wants 1M impedance. Alix has inputs of 330k, 1M, 10M, I can't tell the difference with either choice. Output impedance is 150 ohm.

Becos CompIQ (buffered when on) has an input of 1M and output of 100 Ohm. Not sure why that colors the tone so much if it's first in the chain, but sounds great after the Alix.

Klon (buffered bypass) has a 2M input and 100k output. This is probably designed to go into an electric guitar amp with that high of an output impedance.

So sorry about the runaround... I'm still trying to figure this stuff out.

[lkingston]

This is probably too obvious…but you know…just in case…

You are using a high quality, low impedance, short as possible cable into the Alix…right?