Double Bass Red Eye Preamp

[Jim Dombrowski]

“The Red-Eye Preamp’s impedance-matching field-effect transistor input circuit is designed especially to match and track the impedance of passive piezoelectric pickups.”

There is no vacuum tube in the Red-Eye. The Sarno Black Box uses a tube, but it is not the tube alone that provides the impedance matching - it is the specific circuit built around the tube.

And no, a tube preamp does not provide some “impedance matching magic” simply because it contains a vacuum tube.

 

[JBarz]

Yeah, I get that there are no tubes in the redeye - I was just vamping off something someone mentioned in passing earlier in this thread (?) about this being the inherent nature of how tubes work (the variable impedance matching mumbo jumbo that I wouldn’t even know where to begin to understand…). I extend the word ‘nerd’ as the highest of compliment, btw.

 

[crd]

The Sarno Blackbox definitely sounds great with the Realist. If my name ever comes up on the trial I will A/B the Blackbox with the Red-eye. I am really curious about what the impedance matching per-note is all about. To be honest, the only reason why I need a buffer at all is cause I like to use the Fdeck but I do not like 10meg with the Realist.

I am definitely curious that the Red-eye sounds better 2nd in the chain after the Noble/SushiFX. I know that guitarists who use a bunch of pedals sometimes use a buffer at the end of there chain before there amp. I followed @JeffKissell example and sprung for the SushiFX More pedal which I am excited to play with when it comes. I am hoping to replace my beloved WW's with something that sounds similar so am hoping combination of pedals and the Grace Designs Felix will get me in a similar tonal space.

 

[steve_rolfeca]

….The Sarno Black Box uses a tube, but it is not the tube alone that provides the impedance matching - it is the specific circuit built around the tube.

And no, a tube preamp does not provide some “impedance matching magic” simply because it contains a vacuum tube.

It depends on what the designer is after, but classic tube preamp designs are down around 200k input impedance, which is horrible with an unbuffered piezo.

 

[Jeff Kissell]

It depends on what the designer is after, but classic tube preamp designs are down around 200k input impedance, which is horrible with an unbuffered piezo.

The Sushi Box Slampegg X is a pretty faithful take on the Ampeg B15/B25 preamp stage. Those flip tops had a couple of input options that play nicer with a piezo like the Realist. 5.6Mohms is what this one has.
Honestly, for me, it’s doing more than the Red Eye but the two together are pretty great.
I was really happy with the sound last night which was just the Slampegg into the Red Eye as a DI to FOH. The sound in the monitors and FOH was very even, warm and articulate without the typical piezo brittleness.

 

[Ric Vice]

Here's what Brad Sarno has to say about piezo pickups and tubes.

"the big secret I’ve discovered with piezo’s and tubes is that by the sheer nature of a tube’s inherently very-high impedance, a tube can very smoothly and naturally track the wildly fluctuating output impedances from a piezo. When a piezo sees a solid state device, they seem hard, harsh, barky, and crispy-

distorted. Then so many people try to EQ those problems away. Midrange parametric surgery, high end darkening, etc. But when a piezo sees a tube grid, there’s an amazing dance there, they just get along so well. The response from the pickujp becomes MUCH more smooth and normal, natural sounding, more like

a good microphone than a pickup. So that’s where the Black Box comes in so handy with bass, guitar, fiddle, etc. It just smooths things out so much the player may not need all that complex EQ offered by the many acoustic preamps out there. It becomes so much easier to find a natural and balanced tone."

 

[crd]

It all seems kind of like we are spinning wheels without some precise testing. I understand that takes a lot of time to do that sort of thing so I am not criticizing or volunteering. I get the idea that you have to field test something to know it's use. But I can tell a lot from di a signal and a/b tests. (Especially if they are gain matched !!!) The idea isn't to replace your acoustic tone or use the di for recording but if you get your signal nice direct, it only gets better when you use it through a speaker.

The Fire-eye and Blackbox claim to do similar things. The Fire-eye does claim to match the impedance to the pick-up and frequency of the note you are playing which seems novel and unique. The only other place I've ever seen a similar claim is on this uber expensive fancy German tube-amp.

Impedance is kind of a quirky complicated beast. Everything with cables has a certain input and output impedance that can be optimized.

When I hear the Red-eye is helping people between their chosen preamp it seems like they are just getting a more optimal impedance match between their preamp and there power amp. One of the pitfalls of having a separate preamp/power amp is it opens a can of worms about how to best drive the power amp. I've found the Felix seems to be best matched to go right into the instrument input of an amp rather than bypassing an amp's preamp and going into the effects loop. I think this may have something to do with proper impedance matching? I'm not sure. There are a lot of variables at play.

 

[crd]

Red Eye arrived yesterday. I fired it up today. It sounds OK (even... no hot or cold notes), in my practice room, (which is meaningless, IMFO.)
I'll try it out this Saturday on my trio gig (drummerless, real piano, saxophone - no PA), and report back. (Underwood single element on E side of bridge/Red Eye/WW Electracoustic/12" Eminence in my DIY cab.)
Also - It is built like a tank! Very solid construction.
Thanks.
View attachment 4867593

How was this on your gig? Is it still seeming to improve the WW?

 

[Don Kasper]

How was this on your gig? Is it still seeming to improve the WW?

Yes...but, I had a lackluster nite and will need to reevaluate at a later date. I'll report back at that time.
Thx.

 

[BlueRock]

It all seems kind of like we are spinning wheels without some precise testing. I understand that takes a lot of time to do that sort of thing so I am not criticizing or volunteering. I get the idea that you have to field test something to know it's use. But I can tell a lot from di a signal and a/b tests. (Especially if they are gain matched !!!) The idea isn't to replace your acoustic tone or use the di for recording but if you get your signal nice direct, it only gets better when you use it through a speaker.

The Fire-eye and Blackbox claim to do similar things. The Fire-eye does claim to match the impedance to the pick-up and frequency of the note you are playing which seems novel and unique. The only other place I've ever seen a similar claim is on this uber expensive fancy German tube-amp.

Impedance is kind of a quirky complicated beast. Everything with cables has a certain input and output impedance that can be optimized.

When I hear the Red-eye is helping people between their chosen preamp it seems like they are just getting a more optimal impedance match between their preamp and there power amp. One of the pitfalls of having a separate preamp/power amp is it opens a can of worms about how to best drive the power amp. I've found the Felix seems to be best matched to go right into the instrument input of an amp rather than bypassing an amp's preamp and going into the effects loop. I think this may have something to do with proper impedance matching? I'm not sure. There are a lot of variables at play.

This brings up something sort of related I was wondering about. Hearing people using 2 buffering preamps like the Red Eye and Noble what's going on between input and source impedances in that signal chain vs running the Red Eye first?

From Fire Eye:
"The Red-Eye Preamp’s impedance-matching field-effect transistor input circuit is designed especially to match and track the impedance of passive piezoelectric pickups."


A Noble has an input impedance of 10MegΩ and the 1/4" output is 2kΩ @30hz. So when the Red Eye sees an already buffered signal what's it actually doing with that much lower source impedance that's so magic? Is the impedance-matching field-effect of the Red Eye such a great design concept that it functions well within a broad range of source impedances? If color of a tube preamp is more pleasing earlier in the signal chain why? I trust what my ears tell me but I'd like to understand more technically what's happening with I/O impedances through the signal chain.


I feel like a guy with no theory trying to understand and assimilate why McCoy Tyner sounds different from Bill Evans.

 

[flatback]

I just spent some time A/Bing the tubepre first vs. Redeye first and I gotta disagree (with my different bass pickup amp ears etc) but the REDEYE first in line does the magic for me. The Redeye second has too much microphonics and too much bass impedance even with my variable impedance input on the Sarno V8. The Redeye first and then into the tube preamp gets you perfect impedance balance with no microphonics and a totally clear well balanced sound. From there I can add or subtract bass or treble or mid and easily get to perfect. But with the Tube Preamp first, I feel like "Why Redeye?" after that.Personally I think the mojo of the Redeye is in the Impedance matching which means it is first in the SC. If you had a tuner with true bypass in front of the Redeye it would pass on the Imp to the preamp but the tube pre does not do that. I want to try that little Sushi box, it would fit on my pedal board (I'd let go of the Fdeck) and if it tube warmed the sound without a big box great (I'd transfer my NOS RCA 12AX7 from the Black Box)
But my vote is Redeye>Tubepre>Poweramp

 

[Bruce Calin]

Used it on two gigs this weekend(amazingly quick delivery!). They were very different types of music where I would normally have to have quite different tone setups. The RE made it possible to use pretty much the same for both-nice and clear, very even across strings and registers. It was even better after I actually read the directions and figured out the best way to use the various controls. The technical discussion has literally no meaning(or interest) for me, but the results that I can hear are impressive. I went back and forth between the Ehrlund(great sound, less output, a little wolfy, probably from placement) and an old Clevinger Natural Presence(much more output, more colored tone, more low end) with nothing else before the amp input besides the pickups. Both were very usable with no extra anything. The Clevinger was effected more by the RE, definitely in a positive way. I very seldom buy new gear anymore besides strings, and those not very often, but this seems to be a very worthwhile purchase.

 

[JBarz]

For what it’s worth to the subjective collective experience with this red eye pre : I’ve just discovered mine gets along with other pedals (tube pre included) way better through it’s own effects loop. The XLR to 1/4” cable I dug up the other day let’s me plug direct into my PJB powered cab. Pretty slick - I wonder if it somehow buffers the signal on the back end to keep it clean and clear. I don’t know - this stuff is a mystery to me.

 

[basss]

Is that a line level input on the PJB cab?

 

[JBarz]

Is that a line level input on the PJB cab?

Aye, ‘tis.

 

[basss]

Wait I just saw that you are going xlr out of the red eye, correct? I'm wondering how the red eye's 1/4" out does into a line input.

 

[Jim Dombrowski]

From Fire Eye:
"The Red-Eye Preamp’s impedance-matching field-effect transistor input circuit is designed especially to match and track the impedance of passive piezoelectric pickups."

Why would you put it anywhere else in the signal chain?

 

[Ric Vice]

It depends on what the designer is after, but classic tube preamp designs are down around 200k input impedance, which is horrible with an unbuffered piezo.

I’m unfamiliar with what preamp you’re referring to but the Ampeg B-15 has three different input impedances all higher than 200k. The primary input on Channel 1 is 5.6 Meg Ohms while Channel 2 is 2.2 meg ohms. So there are exceptions.

 

[flatback]

Field-effect transistor - Wikipedia

 

[Jim Dombrowski]

I’m unfamiliar with what preamp you’re referring to but the Ampeg B-15 has three different input impedances all higher than 200k. The primary input on Channel 1 is 5.6 Meg Ohms while Channel 2 is 2.2 meg ohms. So there are exceptions.

Yeah, but who owns one and would drag it to their upright gig?