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Blackstar Unity U500 500w 2x10 combo and U250ACT 250w 1x15 active extension cab.

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Posted (edited)


When I first got this rig delivered, I just enthusiastically went plug and play, with little thought given to much proper adjustment to the controls. After an hour or so of playing time, I decided to sit down with the setup guide sheet that is provided. A few things made a little more sense to me after that.

I connected the extension cab to the 500w combo with the XLR cable provided and set the volume to about halfway, for the time being, with the volume control on its rear panel. There are clearly marked cabinet connector sockets for the XLR cable.



I then looked at the U500 top panel and its controls:

Left to right:
Input jack / -15db cut switch and clip indicator / Input gain / Voicing switch / Drive / Drive selector switch / EQ – low, mid + frequency, high / Effect switch / Response / Compressor / Compressor on-off switch / Master volume / Power LED.


Using an active bass, the player should set the cut switch to -15db.
Using a passive bass, the player should set the cut switch to 0db.

I tested the rig with a Fender Precision Deluxe bass and a Rickenbacker 4003W bass

To start with, I turned the drive knob absolutely flat to get rid of the overdrive effects for now and selected OFF for the CHORUS and OCTAVE effects.

Then I adjusted the EQ. I found the LOW knob to be extremely powerful when the inboard effects were added in– to the extent that it shakes the cabs a bit, so I rolled it to about halfway temporarily.

Without them – or with them blended in subtly, I am confident to have the LOW knob set full on. Then I set the HIGH EQ knob to full on. The MID and FREQUENCY knobs make the final fine adjustments to the sound.

Selecting either the CLASSIC, MODERN or FLAT VOICING adds or subtracts body from your sound, to give you more tone. I selected FLAT, but that may change when the rig gets into a venue. CLASSIC and FLAT seem quite similar to me. MODERN boosts bottom ends and mid tones

Heading to the RESPONSE knob, I selected 6L6 (which apparently replicates a 6L6 valve sound).
I switched the compressor on and just engaged the COMPRESSOR knob a little.

If you are going to use the Overdrive, Distortion or Fuzz effects, there is a little bit of adjustment to do. There are blend controls for both on the rear panel of the amp. They need to be blended in carefully against your regular playing volume, otherwise they just give you a terrifying and immediate leap in volume that could potentially damage your speakers. I suggest turning DRIVE knob right down and then blending the effects in to your taste. The blend is very subtle, so keeping the DRIVE setting low to kick off with is vitally important.


Once that was done, the footswitch can be connected to switch the effects on and off. Button A controls whichever of the DRIVE effects (OD, DIST, FUZZ) are selected. Button B controls whichever of the CHORUS or OCTAVE settings are switched on.

Combining the distortion and Octave sounds can give a very interesting and gutsy result (with very careful blending of volumes) and that will be really useful to the more metallic of bassists.

I find the supplied FS13 footswitch that controls the effects a little flimsy and, as I just use a flanger on my line in, along with a tuner pedal, I am just filing the footswitch away. A cable is also supplied, to connect the footswitch to the rear of the U500 in the FOOTSWITCH socket. You can buy an extra FS12 5-way foot controller to control the top combo effects and provide a tuner.

From there in, it’s just a case of experimenting with the voicing and response settings and setting your input gain and master volume and away you go.

I notice that after being on for quite a while, there is no heat given off and no smell from the rig. It is also pretty silent when the jack is out and the master volume is left turned up.

It’s a really solid sounding amplifier setup, well-constructed and really attractive. Not stupidly expensive and the rig could be extended with further ACT 250's that can be daisy chained together. It is feasible to have a pair of U500’s and a pair of ACT 250’s running, but the player would probably need to link the two 500w combos via a splitter box and then go to the two inputs.

Last thing, switch the extension cab off first, as it doesn't like the combo being turned off first at all.

IN LIVE USE… Based on a 4-gig weekend, using this rig exclusively.


I have come to this rig from a Hartke HA3500 and 2x10 and 4x10 cab setup that suits me perfectly.

I admit that it is not realistic for me to expect this rig to get that sound.

My findings over the weekend were mixed. For the first two nights, I just used a couple of passive basses (Rickenbacker 4003W and USA Fender Jazz bass) and I managed to get a decent, solid tone from the rug after some trial and error and fine adjustment. I still avoided the DRIVE effects and the OCTAVER effect, as I have no use for them.

At stage volume, I think the DRIVE effects and engaging the knob to blend them in would really make the amplifier work really hard, unless you experiment at some length beforehand with the input gain and master volume. I am sure that someone who buys these amps for this purpose will work this out and report back.

The LOW and HIGH settings need to be backed off on a bit when working at stage volumes. For the second pair of shows in the weekend, I took two active basses along for the ride – a Fender Precision Deluxe and my trusty Hamer 12-string bass. These initially seemed to be more than the amplification could cope with, as the 500w cab rattled, but backing off on the LOW setting meant that the amplifiers put out a decent bass signal again. They are very directional, so, while our drummer was pleased that my bottom end was not sounding as ferocious to him, out front, watching video of the final show of the weekend, my Fender bass was extremely powerful, projection-wise. More noticeably so far away, than from just standing in front of it.

It took quite some fiddling about to find the setting that delivered something close to ‘my sound’. Now I have it there, I am going to photograph the settings and not mess with them again too much. Working out how to set the mid frequencies was my main issue – too low and the bottom falls out of the sound. Too high and the cabs vibrate. I did think these 500w combo cabs could do with a port hole in the rear, to relieve the pressure on the 2x10 speakers. They have port holes in the front, though.

I ended up rolling some bass off and cutting the mids and got a really great sound.

The extension cabinet does its job, but the tiny switch used for the volume could do with something to show ‘what number you’re on’ when adjusting the volume. It is a bit fiddly to go behind the rig, mid gig, clutching a bass and bend down to raise or lower the cab volume. The main controls on the 500w combo are recessed in the rear of the top of the unit, so they are not easy to see during a gig, if you need to make a fine adjustment.

To sum up, the rig has the potential to deliver a good meaty sound - after lots of experimentation with inputs and the drive and the various valve simulators. It maybe needs to evolve to include a rear port and I could personally live without all the effects, but I do find the chorus quite useful. Someone else may use all the effects at lower volumes and get their desired result. Your mileage may vary.


The Three

The Three


Edited by 12stringbassist
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I have had a couple of messages about my Blackstar rig this week.
I apologise that I can't now answer the questions, as I am no longer a Blackstar Artist.

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