Crookwood Products: Paintpot Pre

The Paintpot Preamp is a 2 channel portable remote controlled mic preamp that can be used by itself, or via a remote controller. It has superb features, good specs and is sonically very clean and neutral. It's been around in various formats for over 10 years, and is widely used by location and studio recording engineers alike.

 

A 2ch Paintpot, complete with leather handle!

Downloads   

• Paintpot Sales Flyer (120K, pdf)
• Paintpot User Manual (559K, pdf)
• Paintpot Hi Res Pictures (HTML index)

All About the Paintpot   

The Paintpot preamp was the first product we designed, back in '93. Since then it's had a couple of makeover's, and now is in it's 3rd incarnation. It's called the Paintpot because it looks like a gallon can of paint, or as some American owners call it, a bucket! This unique styling however has a purpose. The Paintpot was designed for location, or spot recording, and it's shape means that compared to a 19" rack mounted unit:

• It's easy to carry and place on the floor next to a pair of mics. You can even suspend it from it's handle!
• It's easy to connect up to and use, as all the connectors and controls are on the top or high up on the sides. Compare this with a 1U pre sitting on the floor.
• It's built for the job, not for generic industrial racking!

Beyond it's unusual shape, it's packed full of features, and probably the most neutral amplification you will ever come across. Ever.

Key Features   

Pre Amp

• Each channel has a balanced (XLR) and an unbalanced (TRS jack) input. The pre copes with mics, balanced line, unbalanced line and Instrument signals. Each type of input has a special input stage associated with it.
• You can choose between high or low input impedance for each type of input signal (mic, line,-10 and DI). This is particularly useful on the DI and mic inputs.
• A precision low noise 48V power supply can be switched on for phantom mics. A special, (made to order) 130V power supply can be specified for B&K (DPA) 130V mics.
• The output phase can be reversed. The switch is passive, so no extra circuitry is added when using this feature.
• Each channel's gain is digitally displayed, and can be set in 1dB increments.
• The output is hard balanced on a XLR, and the electronics have a high current output capable of driving long lengths of cable.

Digital Outputs

• A full digital option is provided using a 24bit 192 ADC, with an SRC for the highest sound quality, even when locking to external wordclock.
• The SRC (sample rate converter) allows the ADC to run off one ultra stable internal crystal clock, for the best sound quality. The SRC adapts the output sample rate to either the incoming wordclock, or the front panel settings. The noise and distortion contribution of the SRC is less than -140dBFs, providing a near transparent interface.
• Sample rates can be chosen from 44.1 to 192k, and external wordclock.
• Bit depth can be 24, 20 or 16 bit, with full DSP dithering on the 20 and 16 bit depths.
• AES, SPDIF and TOSLINK outputs are provided. The SPDIF output can also be changed to a professional unbalanced AES signal, running over terminated coax. This allows you to use the Paintpot digitally over distances of 200M (700ft) plus.
• Selectable termination of the wordclock, allows you to chain several Paintpots together using a coax T adapter.
• The ADC card can be supplied at order time, or retro fitted at any time in the future.

Mechanics

• The top panel is backlit, so you can use it and read it in low ambient light.
• All features, including gain control, can be controlled locally from the front panel, or remotely by a compact wired remote unit, using a single mic tieline.
• A standby switch allows for a controlled power down of the unit, keeping all audio circuits active, for the best sound quality, but reducing power consumption.
• The last user settings are stored and automatically recalled on controlled power down/ power up.
• All audio connections are made to the top panel for easy connection.

Technology   

We've been making remote controlled audio devices since 1992 and have got quiet good at them. The key to making a great audio device is the choice of circuit elements to do the remote bit. We chose relays from day one, which while expensive and bulky, are the perfect device - no distortions, delays, frequency or level limitations (within reason!). We use relays for all switches and gain elements. The gain circuits in particular act as stepped, switched attenuators, giving perfect repeatable control.

One of the benefits of remote control is that you can place the relays exactly where you want them on the circuit board. Normally with a conventional design, you have got to lay out the front panel first, and then squeeze the electronics around the front panel knobs and switches. Or use lots of wire to join the front panel to the electronics. Now by being able to design the way you want, the whole circuit becomes much smaller and linear - a definite boost for sound quality!

The other unusual feature is our addiction to fully balanced circuitry. Normally designers just put balancing circuits on the inputs and outputs of a box. We keep our circuits fully balanced from input to output, making the design completely symmetrical. This advanced symmetry means that any distortion generated by the design on the hot phase, is matched by an identical distortion, generated in anti-phase on the cold phase. This approach removes the distortions by simple subtraction. It's interesting to note that John La Grou of Millennia Media, and Crookwood arrived at this topology, independently, at about the same time. And both our products are renowned for their neutrality and accurate amplification.

What other design features have we got?

Every element of the design has been thought about in depth, but here's a few other details:

• Noise performance at real levels. The circuits have been designed to give a low noise floor at all gain levels. People often talk about how quiet the Paintpot is, and this is why.
• Wide frequency response. In order to get good HF distortion figures, you need a high frequency response. However too wide allows RFI to enter the pre. We use a wide frequency response, tailored by passive rolloff filters for RFI protection.
• Local Power Supply. Each active device has it's own power regulators, spreading the load across several devices for better heat management. The local regulators also provide better power performance compared with one big regulator powering the whole device, as is common in most other pre amps.
• Intelligent control. There are 2 processors in the Paintpot, a central one, and a smaller local one on the Pre amp card. This processing power lets us do lots of little clever things, like muting the pre outputs when you turn the phantom power on/off (stops big thumps), and memorising front panel settings on controlled power down.
• Wide AC power range. The Paintpot has been designed to work of a wide range of power supply variations. So wherever you are, you can be sure the Paintpot will keep working, compared with other pre's.
• AC Power filter. An expensive power filter is used on the power input to stop spikes and noise on the mains from getting into the audio.
• Anodised Panels. The Paintpot metalwork is made out of light Aluminium, giving it a low weight of just 3.5Kg (7llbs). The aluminium panels are anodised (chemically coloured), giving them a stronger, more robust finish than just painting.
• Modular design. The whole electronics are based on modules, making them easy to upgrade, repair, fault find and exchange.

Specifications   

Pre Amp

• Mic Noise. >128dB EIN at gains >42dB. >126 EIN at gains > 32dB, >122dB EIN at gains > 12dB, 150R source, 20-20k bandwidth.
• Other Noise. Line noise: < -96dBu, 50R source, DI noise: <-95dBu, 47K source.
• THD+N. <0.0005%(-106dB) @ 27dBu out, +27dB gain, @ 1KHz, >600R load, 22kHz bandpass filter. THD does not increase until 0.5dB before clipping.
• IMD. >0.001%(-100dB) @ 27dBu out, +27dB gain, 60Hz/7KHz tone CCIR.
• Stereo Crosstalk. >115dB @ 1KHz, +20dBu out, +40dB gain.
• Gain. Mic: +12 to +72, Line: -15 to +24, Unbalanced Line: -6 to +30, DI:+18 to +72.
• Input Impedance. Mic: HiZ = 4K, LoZ = 1k5, Line: HiZ = 12K, LoZ = 2K, Unbalanced/DI: HiZ = 1M, LoZ = 470K.
• Max Input Levels. Mic: +15dBu, 130V Mic: +27dBu, Line: +42dBu, Unbalanced line, +33dBu, DI: +10dBu.
• Max Output Level. 27dBu into 10K load, >+25dBu into a 600R load: The Paintpot always clips on output first.
• CMRR. > 85dB @ 1kHz, >75dB @ 20kHz, +40dB gain.
• Frequency Response. <0.03dB @ 20kHz, -3dB @ 400kHz and 0.3Hz, any gain, ref 1kHz.

ADC

• Noise. <-120dBFs, A weighted. In practise it's limited by noise of the microphone used.
• THD+N. <0.001% (-100dB) @ -1dBFs, 1KHz.
• Max Input Levels. Aligned with Paintpot outputs. Nominally 0dBFs is +20dBu.
• Outputs. AES, SPDIF, TOSLINK, AES 1V on 75R Coax. Consumer or Pro flags can be set irrespective of output type.
• Sample rate. The ADC samples at 176.4 or 192KHz. The SRC adapts the output sample rate to suit. The front panel settings are 44.1, 48, 88.2, 96, 176.4, and 196 KHz.
• Wordclock. The SRC adapts for the output sample rate to follow a wordclock between 32KHz and 210KHz output rates. The wordclock can be terminated with 75R or not, allowing you to daisy chain the wordclock.
• Bit depth. The ADC is 24 bits native. 16,20 and 24 bit outputs are provided with suitable dithering.

System

• Weight 3.5Kg (7 llbs)
• Dimensions. 28Hx23Wx20D cm
• Boxed dimensions. 33Hx26Wx23D cm, 4.5Kg (8 llbs).
• Power Requirements. 200-240V or 100-120V AC power, 50 or 60Hz, 20W

Prices   

The GBP £ prices below, are the retail price, ex VAT, FOB Crookwood. Please note that the price you pay from a dealer may be different due to carriage costs, import duties, local taxes and currency conversions. The US dollar and euro prices are for information only: you should check with a dealer or with current currency rates for an accurate figure:

FAQ   

What's the difference between the new Paintpot and it's predecessors?

The new Paintpot has the same basic analogue circuitry, but we no longer support the Tilt EQ, MS encoder and Unbalanced output features of the old Pot. The mechanics have been revised to accept the new circuitry, and ADC options have been added.

How have you managed to reduce the cost without loosing the sonic properties of the Paintpot?

By re-engineering the design, we've radically reduced the labour required to build it. This in addition to removing little used features (see above) has allowed us to reduce the price of the new Paintpot by 30%.

Can I drive unbalanced inputs with a Paintpot?

No. The design of the true balanced amplifiers mean they must drive a balanced input. Anyway, it's unwise to run a length of unbalanced cable, due to ground noise injection.

Can I use 130V powered microphones?

Yes, but you'll need a specially built model. This model has a special power supply and adapter cables to support 130V mics. We can upgrade your existing Paintpot however, if you've already purchased one.

Does the Paintpot have a fan in it?

No, the Paintpot is air cooled, and so is completely quiet, and you can use it right next to a mic without any problems.

 

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Copyright Crookwood 2004. This page last updated 12/04/2005 . All manufacturers trademarks are respectfully acknowledged.
Contact Crookwood on Sales@Crookwood.com