Double Bass Gain structure

[eric.damstra]

I have a technical question.
I have a Musima upright bass with a Fishman full circle going into a headway EDB-1 preamp. So far no problems.
The headway is connected to a SWR baby blue combo. But which input should I use?
I don't have the specifications of the Baby blue but I asume they are not very different from the baby blue II.

EDB-1
Output line put nominal 0.5v rms @ 100 ohms

SWR Baby blue II
Passieve/active input 800k ohms
Active input 60k ohms
Effects return 27k ohms

But this leaves me with 4 volume controls. How should I set these? All controls at maximum and adjusting the volume with the master volume or .....?

 

[iiipopes]

Since you have an outboard headway preamp, which is "active" by definition (uses a battery or other external power source, as opposed to a conventional "passive" coil-and-magnet pickup on a standard electric bass) start by trying the active or bottom input. It has extra circuitry to handle the increased output of the preamp (called a "buffer") so you have more usable range on your pre gain knob on your amp, and less chance of overdriving the gain stage into distortion when you're not wanting to. Start with the pre gain and post gain or master on the amp in the 9:00 position and your tone controls at 12:00, and your headway preamp at zero, and gradually bring up the headway. If you bring it all the way up and you get distortion or not enough volume, turn it back down, turn your amp volumes up to 10:00 and start over, repeating as necessary, and experimenting with various combinations of pre and post knob settings on your amp until you get the tone you want. Generally, for clean, master or post gain is usually up a little more than the pre gain on the amplifier. But all setups are different, and your mileage will vary.

 

[eric.damstra]

I ended up with all volume controls at 3 o'clock and the master at 12 o'clock. Tone controls are bypassed on the baby blue and I'm using the active/passive input.

There's only a gain indicator on the input of amp.

Are these settings on the EDB-1 normal ?

 

[JohnDavisNYC]

one thing you may want to try, although it isn't necessarily 'better', is to run the output of your preamp into the effects return of the effects loop... this should bypass the preamp stage completely, feeding the output of your preamp directly to the baby blue's power amp.

one thing to consider, however, is that the parametric nature of the babyblue's eq could make it great for adjusting your sound based on room acoustics. get a really great bass sound from your outboard preamp on studio monitors, or high quality headphones, and then leave it set that way all the time and adjust for room acoustics with the eq on the amp. this way you could also be certain that you're sending a signal you're happy with to the PA/FOH engineer.

cheers,
john

 

[Ric Vice]

I ended up with all volume controls at 3 o'clock and the master at 12 o'clock. Tone controls are bypassed on the baby blue and I'm using the active/passive input.

There's only a gain indicator on the input of amp.

Are these settings on the EDB-1 normal ?

Eric,
I don't know what version of the Baby Blue 2X8 you have but here's some things that might help you use that amplifier. I had the first version of that amplifier. SWR used Bag End 8" drivers in the first version and switched to Celestion 8" drivers in version II. I had both of these speakers and really preferred the Bag Ends. They went with the Celestions to lower the speaker load from 16 to 8 ohms to increase the rms.

As John suggested above, you should seriously consider bypassing the Baby Blue's pre amp running the Headway EDB-1 into the effects return. I have used the Headway with both my Walter Woods MI-400-8 and Walter Woods Electroacoustic Ultra and it just works better this way. Using the Headway EDB-1 into the effects loop just sounds better, because it's pre amp tends to overdrive the front end of an amplifier pretty fast, and it's very confusing, at least to me, to have a dual set of pre amp controls to deal with.

Finally, there is a way to modify the Aural Enhancer on the Baby Blue so that it can be bypassed, or give you a flatter, more even mid boost. Here's a link to that thread
http://www.talkbass.com/forum/f15/swr-aural-enhancer-bypass-643201/ with pictures here http://www.talkbass.com/forum/f15/swr-aural-enhancer-bypass-643201/index7.html. It would have to be done by a technician, but what you get as a result is the ability to either totally bypass the Aural Enhancer, change it's frequency curve, or revert to it's original settings. In the picture below you will notice a little DPDT switch right above the Aural Enhancer.

Ric

 

[eric.damstra]

I have version I but the bag end woofers were replaced bij Eminence. Those must sound more like the bag end woofers, they say.

I don't know if it makes much difference when I use the effects return because I have the tone controls already switched off. But I will try it.

Does bypassing the aural enhancer really make a big difference? Een turned to 0 it shouldn't influence the sound.

 

[Ric Vice]

I have version I but the bag end woofers were replaced bij Eminence. Those must sound more like the bag end woofers, they say.

I don't know if it makes much difference when I use the effects return because I have the tone controls already switched off. But I will try it.

Does bypassing the aural enhancer really make a big difference? Een turned to 0 it shouldn't influence the sound.

"Not exactly, the mid-scoop is present even with the aural enhancer set to zero (unlike the Enhance control on the Eden and Thunderfunk amps). Up to a 2 O'clock setting the SWR aural enhancer controls how much additional signal from your bass passes through the second half of the 12AX7 tube. This adds gain and extra high end harmonic coloration to your sound but does not change the preset EQ curve present when the control is in the off position. At settings beyond 2 O'clock there's no extra gain, but rather an additional mid scoop added around 200 Hz."

If you have replaced the Bag Ends with Eminence 8" Drivers, those speakers sound excellent in my EA VL 208. That should be a distinct improvement over the Bag Ends, that had foam surrounds, which tend to deteriorate over time. IMHO they would sound much better than the original Bag End's or the Celestions.
The input impedance on the SWR Baby Blue is 800 K ohms and the effects return is 27 K ohms, where the input impedance on the Headway has three settings, the at 1 meg ohm, 5 meg ohms, and 20 meg ohms. The all three of the Headways input impedances are better for a piezo pickup like the Fishman. My preference would be
to use either the 1 or 5 meg ohm settings.

 

[shwashwa]

i feel just the opposite. i run my preamp into the passive/active input so i can get the tone running through the tube. i really like how it sounds. there is something to that effect in the manual to about using a preamp first in order to hit the tube with some gain and get some breakup. i use it for my upright, and while i dont want "distortion" i really like the warmth i get from this amp when hitting that tube with some gain. i also run with the EQ bypassed

 

[eric.damstra]

I tried all inputs with a headphone on. The passive input sounded a little muddy to me. The passive/active input sounded better. The effects loop in sounded most natural, probably because it bypasses the aural enhancer and tube preamp.

Still in doubt 'cause the preamp adds also some tube warmth I really liked. I will try both options next week during a rehearsel with my big band. In a band situation things can work out different then at home.