Do I need a pre-amp?

[mortware]

Newbie question time...

 

I have a Washburn T24 (passive) bass, going into a Tuner > Compressor then straight into a Aguilar TH500. The DI out on the amp goes into our PA to try and fill the room a bit more.

 

The main problems I'm having are:

1. I get a lot of complaints about not being loud enough. The amp is often maxed out
2. The compressor gives off a pretty bad hiss in everyone's in-ears (not that noticeable during play)
3. If I turn up the gain on the PA, it gets quite distorted

 

I've started to think that my bass might need it's signal boosting before it hits the pedals - I'm not even sure those are the correct words... but I wonder...

 

1. Do I need a pre-amp?
2. If yes, I'm guessing it goes before the tuner in the signal chain?
3. Generally speaking, do passive basses usually need a pre-amp?
4. Could my guitar be at fault somehow?
5. Why do people DI out from a pre-amp into a PA AND use an amp? How would the PA get any effects if it's first in the chain?

 

Happy to be educated!

[Lozz196]

The TH500 is a loud amp, what speaker are you hooking it up to, as I had one and I think I would have blown my eardrums out running it anywhere near max.

 

In general (and as an answer to Q5) I run a preamp pedal to always have the same sound to the FOH, irrespective of what amp/cab is on the stage. This way I can also adjust the amp to suit my on stage needs without it affecting what the audience hear. 

 

 

[Bassmidget209]

Yeah I would agree, the preamp would only increase the gain further. I would say either you need an extra cab (if your current one is running at 8 ohms, adding a second one OR getting a single cab to run at 4); or possibly look at the pa situation. In Most situations the PA does the heavy lifting volume wise. The amp gives you colour but the PA is the canvas size....to continue the terrible metaphor 🤣

[warwickhunt]

In simple terms bass amps have 2 sections pre / power.  

 

The preamp section takes the signal from your bass (passive or active) and boosts it, generally by some form of pot / gain control to a level the power amp needs and then the power amp gives you the level for your speakers.  Some amps have a button before the preamp which can be labelled Hi/Lo Active/Passive which helps match input levels.  

 

A preamp 'before' your amp simply means that you won't turn the input gain up as far or need to use the active/passive button.  

 

The DI level should be matched at the desk so that is not your amps problem.  If you need more volume from your gear on stage I'd say the issue lies with your speakers... not enough of them or not sensitive enough.

[Downunderwonder]

1st order of business, take the compressor and tuner out and see what bass into amp does.

 

Generally it takes a lot of experience to get to where DI bass through PA to fill a room is going to be better than a decent cab with 500w behind it, no matter how many toys you put in between. With bass a 'blend' very quickly turns to muddy stew out front.

[Bill Fitzmaurice]

+1. By and large you want to high pass the bass in the PA around 150-200Hz. That way the directional mids and highs get dispersed throughout the room by the PA, without adding lows that the backline amp will usually provide enough of. The exception would be a very large room.

[prowla]

I'm not sure what the purpose of the amp is if you're using the PA and IEMs?

[mortware]

4 hours ago, prowla said:

I'm not sure what the purpose of the amp is if you're using the PA and IEMs?

Great question - The PA doesn't have any kind of dedicated bass cans or anything, so I was told to keep using my amp and speaker on stage. Plus I like the feels on the back of my legs 

 

11 hours ago, Lozz196 said:

what speaker are you hooking it up to

 

Yes I should have said that! I've been using an Ashdown MAG 210T Slim Cab. It's 8ohms so I think I'm only getting half the output from the amp at best right? That being said - Paul Turner (namedrop) sold me his Aguilar GS410, which I've paired up with the 210 on a couple of larger gigs. It's a freaking beast, but I still have to max out the amp to get it louder than the drummer. I'm considering selling both for a Barefaced SuperTwin - for the portability and just having a single 4ohm cab. First I need to figure out where things are going wrong.

 

11 hours ago, Downunderwonder said:

1st order of business, take the compressor and tuner out and see what bass into amp does.

 

It's very much the same. The compressor is "boosting" the gain somewhat, with how I've got it dialled-in... but recent experience has taught me that I should hear the bass at the same volume with compressor on or off - so I'm likely mis-using that.

 

So I can only think that I have a very low-volume bass?

 

11 hours ago, warwickhunt said:

In simple terms bass amps have 2 sections pre / power.  

 

The preamp section takes the signal from your bass (passive or active) and boosts it, generally by some form of pot / gain control to a level the power amp needs and then the power amp gives you the level for your speakers.  Some amps have a button before the preamp which can be labelled Hi/Lo Active/Passive which helps match input levels.  

 

A preamp 'before' your amp simply means that you won't turn the input gain up as far or need to use the active/passive button.  

 

The DI level should be matched at the desk so that is not your amps problem.  If you need more volume from your gear on stage I'd say the issue lies with your speakers... not enough of them or not sensitive enough.

 

This is the bit that confuses me... If I understand correctly, you're saying the TH500 has it's own pre-amp? Would that mean my bass needs to to go directly into it? Or does it boost the gain down into the pedals, then into my bass? I've seen the POST/PRE switch on the front, but it doesn't seem to do much with my setup. I don't use the SEND or RETURN jacks - should I be?

[warwickhunt]

EVERY bass amp has a pre amp 'section' (and a power) but they are just built into the box as a unit; hence you can buy separate pre amps and/or power amps if you want to.  The preamp also does all of the tone shaping (EQ) before it passes your signal to the power section.  
 

The TH500 will send nothing 'to' your pedals nor does anything go 'into' your bass.  Most of the time it doesn't matter which of the 2 routes you go:
bass>pedals>amp>cabinet
bass>amp>pedals[via send/return]>cabinet

You can try putting the pedals in the effects loop if you like but personally if you go: 

bass>amp>cabinet

and it isn't loud enough then you've got something wrong somewhere!  

 

Post / Pre switch is associated with your DI out.  It basically dictates if the DI signal goes from the amp before (pre) or after (post) the EQ.  

 

There is either something wrong with your gear or your band if you are using a TH500 + 4x10 + 2x10 and you still have issues with 'volume'.  That rig should easily compete on stage with any drummer.  

 

There are loads of variables in what you are describing but you need to ensure the basics are right; cables are all OK (you are using proper speaker cables not guitar/instrument leads?), speakers haven't been messed with and are out of phase with each other, your bass 'works' (have you tried a different bass into your amp and cabs?), get your pedals out of the way for now, EQ is centred and not set fully anti-clockwise, button above input is out (not pressed in), you are using the input gain knob at 12:00 or possibly higher... have you read the manual? 

 

http://www.aguilaramp.com/wp-content/uploads/TH500-Manual-6.0.pdf

 

Edited September 20, 2022 by warwickhunt

[Merton]

@mortware - what are your EQ settings?

[Lozz196]

I think try and borrow another bass and amp from somewhere to try and find out where the problem lies - the TH500 connected to those two cabs making a 610 should be deafening, there`s something wrong somewhere. 

[Downunderwonder]

1 hour ago, warwickhunt said:

if you go: 

bass>amp>cabinet

and it isn't loud enough then you've got something wrong somewhere!  

This.

 

Possible your cabinets are incompatible with one another. Plug in the 410. It should be plenty plenty loud all by itself. If adding the 210 makes it less loud or less clear you can forget that plan.

[mortware]

Thanks all - this is all great info, and shows considerable gaps in my knowledge.

 

I need to test everything at home properly... I usually test all this at a gig. Which means my neighbours won't be happy

 

I'm still suspicious of my bass being at fault - but I have another one I can try. 

 

Essentially (if I understood correctly) I don't need a pre-amp for FOH - the amp's balanced out should be enough. Something else is wrong.

[warwickhunt]

1 hour ago, mortware said:

Essentially (if I understood correctly) I don't need a pre-amp for FOH - the amp's balanced out should be enough. Something else is wrong.

 

Your bass amp has a balanced DI out (3pin XLR type), which is what drives your PA desk but forget that for now.

 

You need to sort out why your onstage sound is quiet, fixing that will likely sort any issues with your desk distorting or whatever else seems to be the issue.  

 

I have no idea of your level of equipment experience re knowing how to set input/EQ/output but your amp (or any 500w amp) through a 410 or 610 (with your 2 cabs) should be smashing down walls, especially if you are getting anywhere near the max you can get out of your amps output.  If you know another (experienced) bassist, see if you can swap items in and out of your 2 set ups (assuming he has an amp and cab); alternatively ask the guy who runs the studio you rehearse in if he can have a quick look at the way your amp is plugged in/set up.

[Chienmortbb]

I think you need a new drummer. Seriously though the TH500 uses the 250ASX2 power module that from memory gives close to full output at 8 ohms. This is a line from the ICEPower datasheet. "500W @ 1% THD+N, 20Hz – 20kHz, 8ohms, BTL".

 

Clearly the preamp in the amp has its own baked  in sound, according to a friend, and many on-line reports. However, this would not affect the real output of the amp. You should be able to melt the drummer, even with an 8 ohm speaker.  Have you tried a different amp? There may be a problem in the amo.

 

Edited September 20, 2022 by Chienmortbb

[mortware]

17 minutes ago, Chienmortbb said:

I think you need a new drummer. Seriously though the TH500 uses the 250ASX2 power module that from memory gives close to full output at 8 ohms. This is a line from the ICEPower datasheet. "500W @ 1% THD+N, 20Hz – 20kHz, 8ohms, BTL".

 

He is a very loud drummer >.<

That's great info to know - I always wondered how it was performing considering it's a single 8ohm cab.

 

45 minutes ago, warwickhunt said:

alternatively ask the guy who runs the studio you rehearse in if he can have a quick look at the way your amp is plugged in/set up.

 

I didn't think of this... the only time I ever get to speak to a fellow bassist is before or after a gig - and we're usually too busy setting up! 

 

Thanks again - I'll report back soon

[gjones]

Very odd that you're having problems hearing yourself with a loud amp and 6 speakers.

 

I would remove the tuner and compressor and see if that helps. If it doesn't, then you have a very quiet bass.

[Osiris]

4 hours ago, Merton said:

@mortware - what are your EQ settings?

 

That's what I was wondering too. Are you going for that scooped mid range sound, i.e. lots of lows and highs but with not a lot going on in between? If you are then I suspect that's where the problem lies. While a scooped sound can sound great when it's just the bass playing it's often the last thing you actually need to get the bass to be heard in a band context. Most of the audible frequencies of the bass are in the mids, so that's where you need to shape your sound. IME the sounds that work best with the band are not usually very exciting on their own but you need to be able to sit in the mix with the other instruments for the bass to work as part of the whole. And from memory - so I'm happy to be corrected - the bass control on the Tone Hammer is centred at 40Hz which is a very low frequency, and if you're boosting the bass control lots all you are doing is putting a big strain on the speakers, especially a single 2x10, and not really getting anything audible, or of much use, out of the speakers.  

[jezzaboy]

If you have a 4 x10 and a 2 x 10 running from a TH500 and you still can`t be heard over the drummer, either you or your band have some serious problems 

 

I used one of those Ashdown cabs with MAG 300 head a few years back in quite a loud band and could be heard fine. They aren`t the best cabs but all the same. Can you not borrow another head from someone, ditch the pedals and try going right into the amp and see if it`s loud enough?

Edited September 20, 2022 by jezzaboy

[jezzaboy]

1 minute ago, jezzaboy said:

If you have a 4 x10 and a 2 x 10 running from a TH500 and you still can`t be heard over the drummer, either you or your band have some serious problems 

 

I used one of those Ashdown cabs with MAG 300 head a few years back in quite a loud band and could be heard fine. They aren`t the best cabs but all the same. Can you not borrow another head from someone, ditch the pedals and try going right into the amp and see if it`s loud enough?

Sorry, I should have read the other replies before posting 

[Downunderwonder]

7 hours ago, Osiris said:

 

That's what I was wondering too. Are you going for that scooped mid range sound, i.e. lots of lows and highs but with not a lot going on in between? If you are then I suspect that's where the problem lies. While a scooped sound can sound great when it's just the bass playing it's often the last thing you actually need to get the bass to be heard in a band context. Most of the audible frequencies of the bass are in the mids, so that's where you need to shape your sound. IME the sounds that work best with the band are not usually very exciting on their own but you need to be able to sit in the mix with the other instruments for the bass to work as part of the whole. And from memory - so I'm happy to be corrected - the bass control on the Tone Hammer is centred at 40Hz which is a very low frequency, and if you're boosting the bass control lots all you are doing is putting a big strain on the speakers, especially a single 2x10, and not really getting anything audible, or of much use, out of the speakers.  

^ Pay close attention to this.

 

If it's not this then something is broken, possibly a result of said low EQ abuse.

 

There's an easy test you can make on any cab with a 1/4" input jack.

 

9V battery applied across the exposed cable end, tip +ve, will make the speakers pop out when the -ve hits the cable shaft. All going well it will give you a big fright with the bang it makes.

 

If one or two stay still or move backwards you have miswired or broken speakers. 

 

 

[blisters on my fingers]

This is great advice from Downunderwonder, and it will show non-functioning/broken speakers, or speakers that are wired out of phase.

 

Out of phase speakers will be "fighting each other" and will wreck the sound.

 

After you've checked each cab individually, repeat the battery test with both cabs wired up together. *

 

All the speakers in both cabs should move in or out together, if not something is wrong. 

 

And if so it is a very simple fix. Let us know how you get on with that.

 

 

* Apologies .... I was assuming that the cabs are daisy chained (speaker cable into 1st cab, another cable from 1st cab into cab 2).

I'd forgotten that the TH500 has two Speakon outputs.

If you using both Speakon outputs to each individual cab then it will be a bit more of a faff to check the phase of the cabinets is correct, but not impossible.

 

How are you connecting the cabs to the amp?  Do the cabs have Speakon or jack inputs? Are both cabs 8 ohms?

 

And please  please  please

 

Whatever you do....   do not put a 9v battery across the instrument cable into the amp  !!!!!!!!!! 

 

 

 

 

 

 

 

 

 

 

Edited September 21, 2022 by blisters on my fingers
must read before posting

[prowla]

7 hours ago, blisters on my fingers said:

Whatever you do....   do not put a 9v battery across the instument cable into the amp  !!!!!!!!!!

I have to say I first read it as that and thought WTF????

[lemmywinks]

Plug the bass straight into the TH500 and use a single cab. Set the eq flat, the -10db button out and drive to 0, set the gain until the clip light comes on then back it off a little until it doesn't. If it still sounds bad/quiet then try with the 2x10.

 

Sounds like an input gain issue to me so pay attention to the bit in bold.

Edited September 21, 2022 by lemmywinks

[Downunderwonder]

41 minutes ago, lemmywinks said:

Plug the bass straight into the TH500 and use a single cab. Set the eq flat, the -10db button th out and drive to 0, set the gain until the clip light comes on then back it off a little until it doesn't. If it still sounds bad/quiet then try with the 2x10.

 

Sounds like an inpout gain issue to me so pay attention to the bit in bold.

Sounds like this is the voice of experience with this amp. Either way it will serve very well in diagnosis.