Direct Boxes for Bass?

[Guitargodgt]

I agree with farview on the can/can't thing. It seems like solid state amps would put up with it better. I have never seen any sort of tube amp that you could run without a load on it.

I always do it out of the ol' better safe than sorry mantra.

 

[ecc83]

I agree with farview on the can/can't thing. It seems like solid state amps would put up with it better. I have never seen any sort of tube amp that you could run without a load on it.

I always do it out of the ol' better safe than sorry mantra.

Well you can't actually RUN the power amps I was working with without a load but unless a jack was inserted into both the input and a speaker socket the OP valves are biased off . It is really a safety feature but it is possible to run the amps as pre amps with no speaker connected and the master turn to zero.

N.B. This applies to almost all amps in the range but not the hand wired A series.

Dave.

 

[Farview]

Awesome! I wondered how they did that. I knew at least some amps let you run them without a speaker, but I never knew how that worked.

 

[jokerone]

Awesome! I wondered how they did that. I knew at least some amps let you run them without a speaker, but I never knew how that worked.

I'm told that Solid State amps are ok to run without a load. Tube amps you will burn up quick.

 

[Farview]

I'm told that Solid State amps are ok to run without a load. Tube amps you will burn up quick.

Did you read what ECC83 wrote? "valves" are tubes on the other side of the atlantic. He is talking about tube amps.

 

[jokerone]

Did you read what ECC83 wrote? "valves" are tubes on the other side of the atlantic. He is talking about tube amps.

Yes, what I'm wanting to do is run the amp head (ampeg portaflex PF-500) and have the audio come out of the XLR line out to the mixer without running any "power" to an actual amp itself. I believe based on what I read for Solid State this is possible and won't harm anything.

thanks

 

[Farview]

yes, you can.

 

[jokerone]

yes, you can.

cool. thanks.

 

[damianhk]

just searched "bdi21", and went to end of thread. If i purchase the behringer bdi21, do i need a compressor, or does the amp simulation compress the signal? I know it's a newbie question.

 

[Farview]

just searched "bdi21", and went to end of thread. If i purchase the behringer bdi21, do i need a compressor, or does the amp simulation compress the signal? I know it's a newbie question.

It depends on which amp simulation you use. A distorted SVT sim will be all the compression you need. Some other sims might not be compressed enough.

 

[RecordingMaster]

If your bass has passive pickups, your best bet is an active di. If you have active pickups, it doesn't matter.

I've always used a passive DI box for an active bass for fear of running it through yet another stage of (unneeded) amplification and just because I always thought that was "the thing to do". Or I just bypass the DI box if there is a "line" input on the pre. The first time I ever tried plugging an active bass into a "Hi Z" jack on a pre/interface, was certainly my last time. Seemed like it lopped off a bunch of top and low end and just made things sound weird in general.

But who the hell am I?!?!?!?

 

[BroKen_H]

When I used to record in the 80s, we always ran a DI box, but then also put an LDC about 12" away from my cab at the bottom of one of the 10s. (Peavey 1820 cab) Got good mixable bass tone then, and still use the same technique today. Although my MXL 2001 is not as good a condenser as the studio mikes, I still get a really clean strong signal. If I kick the drive on the B100, it gets a really nice "glow".

 

[ashcat_lt]

I've always used a passive DI box for an active bass for fear of running it through yet another stage of (unneeded) amplification and just because I always thought that was "the thing to do". Or I just bypass the DI box if there is a "line" input on the pre. The first time I ever tried plugging an active bass into a "Hi Z" jack on a pre/interface, was certainly my last time. Seemed like it lopped off a bunch of top and low end and just made things sound weird in general.

But who the hell am I?!?!?!?

But the passive DI attenuates the already-probably-hot-enough signal from the bass which then generally requires gain at the mic pre to get it back up. An active DI at unity would not add any amplification, but would be another circuit to add noise or whatever. Straight into the line input would be your purest possible path.

 

[ecc83]

I often think we should preserve a bit of sense and reason regarding "minimalist, clean gain paths"!

The output from a guitar pickup is going to be a bit distorted anyway because they are "single ended" devices . An active DI is usually just a unity gain buffer and so even the meanest, cheap TLOXX chip will have virtually un measurable distortion and even if it HAD bit of gain it would still be very clean.

Recent information shows that the instrument input on some AIs is probably the worst culprit but even here keeping the level down should sort things out.

Just found this..
http://www.radialeng.com/pdfs/Selecting-a-DI-box-for-bass.pdf

Some of the levels are bit OTT but tis interesting!

Dave.

 

[RecordingMaster]

But the passive DI attenuates the already-probably-hot-enough signal from the bass which then generally requires gain at the mic pre to get it back up. An active DI at unity would not add any amplification, but would be another circuit to add noise or whatever. Straight into the line input would be your purest possible path.

No, no no....
You read my reply wrong or I didn't word it correctly. I was responding to how Fairview said passive bass is better with active di, but active basses, it doesn't matter. I was basically saying that I always thought passive bass goes with active di and active bass goes with passive di if the pre only accepts xlr, then of course in both of those scenarios the di would then go into a preamp. Or alternatively for active bass, to plug straight into the 1/4 line in on the PRE AMP.

 

[ecc83]

Hmm,

It all depends upon the relative noise/gain levels of the active DI and the proposed mic pre amp.

Yes, a passive bass into a passive DI will be attenuated (but by a transformer, not "noisy" resistors), typically by 20dB. But most 1/2 decent mic pres should be able to make up that gain without a significant noise penalty.

An active DI has the benefit of a much higher input impedance. 1meg typically as against ~200k at best for a simple transformer. This will preserve a bit more output, especially HF output and might indeed sound "livelier". It is also technically better in terms of distortion to drive transformers from as low a source Z as possible but as I mentioned earlier, I don't think 0.1%THD one way or the other will matter in a guitar circuit!

As for ACTIVE basses? Never had one but it has been the case for 1/2 a century or more for some guitar amps to have a "hi" and "lo" input jack. The level difference twixt the two is almost always just 6dB (and the input Z of the low input, for the high output device, has always been about 68k, NOT the magic meg! Not a Lot of People Know That!) It would seem rather silly therefore if active guitars put out more than 6dB above their passive counterparts since it could lead to overload problems? In fact it would be a poorly designed guitar amp or AI that was bothered but ***t'appen!

I would aver that the MAIN benefit of an active guitar is that it allows of a very low output impedance which gets over cable capacitance issues and induced noise. It also allows better tone and volume control without the loading interactions and "tone suck" of passive designs.

Dave.

 

[Farview]

I would aver that the MAIN benefit of an active guitar is that it allows of a very low output impedance which gets over cable capacitance issues and induced noise. It also allows better tone and volume control without the loading interactions and "tone suck" of passive designs.

Dave.

The main benefit of an active bass is the active tone controls. The rest is just icing. I hate active guitars, but love active basses. I suppose that isn't really true, I hate EMG's but I used to use Bardolini's a long time ago and they were cool.

 

[ecc83]

The main benefit of an active bass is the active tone controls. The rest is just icing. I hate active guitars, but love active basses. I suppose that isn't really true, I hate EMG's but I used to use Bardolini's a long time ago and they were cool.

Now that is interesting! Well, it is if by "active" you mean feedback "Baxendall" types? These are strictly verboten in guitar amps! I don't know of even one design that uses them, all subscribe to the passive "tonestack" or totem pole design.

The big advantage of feedback tone controls is of course virtually no interaction between bass, mid and treble where as passive stacks are horribly (or nicely! Yer pays yer money!) interactive and gitist (say they!) LOVE that!

Must look for some active bass and 6'er shcemos..


Dave.

 

[ecc83]

Had a bit of a shufty round. Mixed bag, some are feedback actives, some just passive tone pots into a chip, some are discrete transistor designs. Seems to be little "convergence" of ideas.

One big problem is that even tho' I put "schematic" into Google it insists on finding 90% WIRING diagrams and the actual electronics is just shown as a "black box"!

Dave.

 

[jokerone]

I bought this one at Gearfest last weekend. Spoke with the rep. He claimed The Edge (U2) uses them (in a rack setup) instead of the Radials more expensive ones because he said, nobody can tell the difference. (got a gearfest discount of $10 too)

Radial ProDI | Sweetwater.com