You are here

TL Audio Ivory 5050 & 5001

Valve Preamp & Mic/Line Amp By Paul White
Published April 1998

TL Audio PA5001.TL Audio PA5001.

TL Audio's Ivory range of affordable valve‑based processors continues to expand. Big game hunter Paul White strikes (c)amp and bags the latest two in the herd (SOS wishes to point out that no elephants were harmed during the writing of this review)...

TL Audio's new Ivory series of processors uses hybrid valve/solid‑state circuitry, with the aim of combining the tonal magic of valves and the low noise and reliability of semiconductors, at a price point acessible to project studio owners. As this point is lower than previous valve products from the company, the philosophy behind the Ivory range seems to be to keep it simple.

5001 Mic/Line Amp

TL Audio 5050.TL Audio 5050.

Presented in a very traditional looking 2U rack case, the 5001 provides four identical mic preamps, all powered by an internal mains PSU. There are no line or instrument input options, and the metering is very basic, with just one LED showing the amount of drive through the valve stage and a second warning of peaks that are within 5dB of clipping. The brightness of the Drive LED gives some indication of how much 'warmth' is being added by the valve.

The single Gain control is continuously variable from 16 to 60dB, with a separate Output Level control adding up to a further 15dB of gain. Phantom power (48V) is switchable, as are phase reverse and a 90Hz low‑cut filter with a 12dB per octave slope. All four mic inputs are on rear‑panel XLRs, and the outputs are available on both balanced XLRs (+4dBu nominal) and unbalanced jacks (‑10dBv nominal). A voltage‑select switch is also located on the rear panel, along with the mains inlet. With the exception of the Power button to the right of the front panel, none of the buttons have status LEDs.

Internally, each channel comprises a solid‑state, low‑noise mic amp followed by a two‑stage valve amplifier based around a single ECC83 dual triode. An audio bandwidth flat within 1dB from 10Hz to 40kHz is claimed, and the equivalent input noise is specified at ‑127dBu for maximum gain. Of course, the really important measure of performance is how quiet the input is at more typical gains, but this is perhaps best judged subjectively under real recording conditions.

5050 Valve Preamp

The 5050 Preamplifier combines a single preamp and compressor, and has a front end based on that of the 5001, except that it adds line and instrument input options. The Instrument input jack is on the front panel, while the unbalanced line out jack is on the rear panel next to the mic XLR socket. On this model the output is on a line‑level, balanced jack only. Again, the circuit is a hybrid design featuring a solid‑state front end followed by a valve buffer, but this time it seems that only one stage of the ECC83 is used. The other resides in the compressor amplifier block. There's no mic‑level metering at all on this model, and no phase switch, though the 90Hz low‑cut filter and phantom power switching have been retained from the 5001. A single Input Gain knob sets the mic gain, up to 60dB, though the Output Fader following the compressor can add a further 15dB to this figure, with yet more gain available from the compressor's Gain Makeup control if required.

Most compressors monitor either their own input or output to derive the side‑chain control signal, but this design appears to do both. Threshold and Ratio are fully variable, as is the Gain Makeup control (+20dB max) with attack and release independently switched between fast and slow. To prevent distortion when compressing low‑frequency sounds at the Fast release setting, the circuit has a built‑in hold time that prevents the compressor from attempting to go into release mode after each cycle of the incoming signal. Gain reduction is shown by a meter above the mic/line amp, and a green LED above the compressor shows the Bypass switch status. A further bargraph level meter is fitted above the Output Fader knob to indicate output level.

Though the compressor has a conventional Ratio control, with a range from 1:1.5 right up to 1:30, the voltage‑controlled circuit has been designed with a soft‑knee response, so the compression ratio actually increases towards the target value as the signal level approaches the threshold. Overall, the technical specification for the unit is similar to that for the 5001 preamplifier.


Despite the use of valves in these units, there's no obvious noise penalty, and the mic amps perform cleanly and transparently. Driving the valves more heavily does produce a thicker tone, but it's not an effect that I actually like on vocals — I think the sound is best when it's clean or very mildly driven. There's no obvious difference in performance between the mic preamps on the two units under review.

I tried the 5050 instrument input with my Strat guitar and found it matched pretty well, giving a clean and lively tone. I've no doubt it would work equally well on bass guitar. However, some EQ would generally be needed to achieve acceptable guitar voicings, and as none is provided, that would have to come from elsewhere. I experienced no problems with the line input.

Moving on to the compressor section, this is surprisingly transparent, to the extent that you really have to push it hard if you want to hear compression as an effect. The effect is most obvious with the slow attack and fast release setting, which imparts a nice glassy edge to guitars and brings out the attack in bass and drum sounds, but most of the time the effect is just a gentle evening out of levels. I didn't really miss not having variable attack and release controls, though a hard/soft setting might have been useful for occasions where more overt compression is demanded. There's plenty of makeup gain, and in combination with the Output Fader this means that there's no problem getting enough level out of the unit, even with relatively weak input signals.


Both these products are well built, clearly set out and easy to use, and both treat the signal being processed with respect. The mic amps are about as good as you'd expect to get in a good mixing console, but because you can patch them directly into your recorder, the resulting signal is likely to be cleaner, as you cut out all that unnecessary routing through a mixer. The 5050's compressor errs on the side of being over‑polite for me, and you seem to have to pile on a lot of gain reduction to get the job done, whether you're after simple levelling or thickness and warmth. The slow‑attack, fast‑release setting works particularly well on transient sounds, but in all other respects I'd say the compressor is competent rather than exciting.

Given the relatively low cost of these units, they have to be considered good value, and their signal integrity wouldn't disgrace a serious professional recording facility. There are better‑sounding products out there, but you generally have to pay a lot more than this to get them. If you want no‑nonsense processors that get the job done simply and cleanly without costing a fortune, the Ivory range fits the bill nicely.


  • Well engineered, with a clear layout.
  • Attractively priced.
  • Hybrid valve/solid‑state circuitry.


  • The 5050's compressor is more workmanlike than exciting.
  • Little or no mic amp metering.
  • The 5001 has no line or instrument inputs.


These are practical and well designed processors that combine simplicity and affordability with a clean audio path.