Frequently Asked Questions

I have recently purchased one of your fine amplifiers and I am very pleased with the sound and performance, but I'm having problems with what i think is some kind of earth loop. When I sing and play bass I get a shock from my microphone. I wonder if you have experienced this problem elsewhere in the world and if there is anything I can do about it.

This is most likely caused by the difference in ground potential between where your Ashdown is connected to the mains supply and where the mixer is connected to the mains supply.

You see the strings on your bass are connected to ground through your guitar and amplifier for safety. The body of the microphone is also connected to ground through the mixer, again for safety. If there exists any difference in ground potential between the two (because they are plugged into different mains sockets) then this potential will exist between your guitar and microphone. This may be only small but you will feel it when you touch the guitar and the microphone. There are a number of solutions to this problem:

1. Make sure the Ashdown and the mixer are plugged into the same mains board.

2. Use a pop shield on you microphone so your lips do not actually touch the metal of the microphone.

I have an original ABM 500 chrome rack. I'm having trouble matching tonal characteristics with my cabinet at times. I like the modern sound the shape button gets, but I lose the upper content.

+8dB @ 50Hz & 4kHz, -8dB @ 400Hz Filter slope = 6dB per octave

I have an ABM C410t-500, the sound is Great, however I have a "hum" when I use the "DI"

The DI is a Balanced, low impedance output intended for connection into a Balanced Microphone input on a mixing desk.

The connection must be Balanced for it to function correctly. If the correct connection has been established then the only possibility of hum being introduced is via any ground connection between the amplifier and the mixing desk. Removing the connection from pin 1 of the XLR should break this ground connection and eliminate any possible source of hum.

However check your XLR cable to see if pin 1 is connected to the metal body of the XLR plug. If it is then you will still have a ground connection via the body of the XLR which is secured to the chassis of the ABM. For a balanced signal you need connection to only pins 2 & 3 of the XLR.

Why you have put the sub-speaker output, on the front of the amp, instead of the back?

It puts out 130hz and lower only, it takes out these frequencies into your standard cabs and redirects them to a powered sub or power amp to just boost the real low end for mega subs.

What's the difference between VU Monitoring on the ABM and the MAG or Electric Blue?

On the ABM the EQ is a 2 stage circuit, each stage of this circuit is monitored separately to ensure that there is no clipping in either stage.

To allow this to be possible it is not possible to monitor from just one point i.e. after the EQ in/out switching. These monitor points are the most likely parts of the pre-amp to become overloaded and clip and it is essential to monitor both. This also ensures that you do not suddenly decend into distortion when you switch in the EQ because it is monitored all the time. On the ABM this is the most sensible approach for a professional product.

On both the EB and the MAG the VU monitoring is after the switching because of the number of comments we have received about this. On the ABM this is not possible (as outlined above).

Do you have any technical specs?

They are in the owners manuals you can download here

I have a hum or buzz when using the DI output on my amp.

Pin 1 is the earth on the Ashdown Di. If you experience earth hum on early non EVO models of Ashdown Bass amps you can simply remove the wire to Pin 1 either in your cable or in the amp (via your local service centre or qualified dealer).

Is the stereo line input on the ABM 500 - pre or post EQ?

Post EQ

Having problems recording to Mini Disc from DI output.

The DI output is a Balanced output intended for connection to the balanced Mic input on a mixing desk.

The input on your Mini Disc is an un-balanced input and this is why you are having the problems.

You would be far better off to use the Line Out from the Acoustic Radiator into the Line Input on your MD, a perfect match and the correct level.

DI problems?

a) Phantom powering should cause no problems on the new updated version of the ABM. Check it is going to a 'Balanced' input on a desk. If it is unbalanced there will be problems. In this case use the 'Line Out'.

b) The DI out is a low level signal intended to match the input level required by a balanced Mic input on a mixing desk ( for D.I. ). This will not be enough to match the level required by any Line level input without boosting it first i.e. through the Mic input channel of a desk or any studio Mic pre-amp. Other than this, for a signal with a higher level use the Line out from the unit.

What are the EQ centres and Q on an ABM pre amp or head?

A. BASS = 50Hz Q = 1
180Hz Q = 1.6
340Hz Q = 1.6
MID = 660Hz Q = 1.6
1.2kHz Q = 1.6
2.6kHz Q = 1.6
TREBLE = 7kHz Shelving

Can I rewire the mains from 115 to 230v or 230v to 115 v?

Yes - For 240v wiring the GREY and Violet wires from the mains transformer primary are connected together. The BROWN and BLUE wires go to the mains switch LIVE and NEUTRAL. For 115v wiring the BROWN and GREY wires from the transformer primary are connected together and go to the mains switch LIVE. The BLUE and VIOLET wires from the transformer primary are connected together and go to the mains switch NEUTRAL.

We strongly recommend that all electrical maintenance is carried out by qualified personal only.

Can I use stereo effects with an RPM1?

The RPM-1 pre-amp is a mono device, if you wish to use stereo effects these will have to be placed between the pre-amp Full Range output (using a Y splitter cable) and the stereo input to the power amplifier. This will give you a full range stereo system.

The only other option for you is to use the High and Low pass output from the pre-amp into the power amp channels A and B for a Bi-amp system. Effects will in this case have to be placed in the effects loop of the pre-amp and will be in Mono.

Effects Loop / serial/ parallel?

The effects loop on the Ashdown is a Serial effects loop i.e. it breaks the signal through the amp when a jack is inserted into the Return socket. You could try returning the effects signal into the Line Input instead, this will not break the signal path through the amp and may provide that you need.

How can I use headphones on an Ashdown ABM or MAG?

The only way is to buy a small battery powered headphone amplifier and plug it into the TUNER OUT with the amp MUTED, or unplug the speakers and use it plugged into the LINE OUT. Other than this if you have a walkman that has a record facility you could use this as a headphone amp.

The amp will come to no harm with the speakers unplugged. It is possible to plug headphones into the speaker output but you risk the possibility of blowing up the headphones if you turn the amp up too far.

Are the signals from the line level inputs of the ABM 500 processed through the effects loop (or are the line inputs summed into the signal path downstream from the effects return bus)?

The Latter (the line inputs are summed into the signal path downstream from the effects return bus).