Little Giant with an audiophile DNA
Lyd audio in almost an intriguing device. A whole amplifier preamplifier and even a RIAA stage in an enclosure that would normally host only a shrink phono module.
LYM AUDIO plan with Audio LYM 1.0T PHONO was not only to created and design another class T amplifier. They wanted to do sompething different. So inspite of the strong competition, low cost and especially the desire to improve the performance of a Chip, the Tripath TA2024C, used in many various forms and circuit solutions, they refined the workings for LYM 1.0T PHONO and tried to make a difference.
They challenged themselvs to create something better. The amplifier under review is with RIAA and it's already in production. The circuit module RIAA has some improvements (less noise and wider dynamic range) than the previous prototype version and it also look slighty different. You can see them in the pictures below.
I asked Lym Audio’s Nino Campo to share the insights of LYM Audio LYM 1.0T PHONO:
1. SMD TECHNOLOGY
Whenever possible, we used SMDs (Surface Mounting Devices) because this type of component has parasitic elements with very low values, due to the absence of leads, the very small size and the fact there is almost no reactive parameters (inductances and stray capacitance).
These parasitic elements, which are almost always counterproductive, are present in THT (Through-Hole Technology). Another additional factor that improves the SMD components is the reduction of the length of the connecting tracks. This means a reduction of the effect of inductive coupling and a reduction of electrical connections between adjacent circuits.
The use of SMD components requires automated assembly: this typically provides precision and repeatability to the behaviour of the circuit and, no less importantly, allows for cost reduction for both the components and the mounting.
2. THE PRINTED CIRCUIT BOARD (PCB)
We designed the circuit board not only to interconnect electrical components, but also to create shielding plans, heat dissipation surfaces for some power components, creating anchor points of mechanical components. A good PCB allows for high current distribution in a very technically precise pattern. The preparation of one or more return points of current, for example one for the power supply circuit, one for analogue signals, and another point for digital circuits, can significantly reduce the interference between the various sections.
A stretch of electrical earthing track, shared between the power circuit and the input circuit, can induce unwanted signals in the latter that can alter the integrity of small signals (audio).
A wise distribution of ground planes lead to, in terms of audio, less noise, less interference between channels, better detail and the manual phase of the assembly will be reduced to the essentials.
From this, we can easily understand how the PCB represents an essential element for the success of this project. The designer carefully considers the PCB component as essential for the success of a piece of electronic equipment, regardless of its use: audio, analogue instrumentation or digital.
The LYM1.0T was designed according to the concepts set out above; looking at the inside you can see how the careful arrangement of the components on the PCB has allowed for an assembly that is free of stray wires, and last but not least, has allowed for a cost reduction for both the components and the assembly.
3. CHIP: TriPath TA2024C
The LYM1.0T is based on the Tripath chip TA2024C. It's a chip with amazing performance, the object of attention of many audiophiles, even those diehards.
LymAudio has invested time and money searching for the best reproduction of the TA2024. The final choice fell on TA2024C produced in a magnificent golden robe across both legs Tab and the bottom (heat slug) for the dissipation heat (there are very few components that receive this high-quality treatment). Not that gold is an fundamental element to the functioning of the device, but if you allowed, shows a clear intention to make things right.
The TA2024C represents a refinement of previous TA2024 and TA2024B, it was the annoying clikpop improved, that occurs at power on and off amplifier, a characteristic of its predecessors. It was improved the efficiency (90% vs. 88%) and also power is changed, 14V against 13.2V of their predecessors.These changes cause an improvement in terms of audio playback and, last but not least, a small increase of acoustic power.
The TA2024C represents a refinement of previous TA2024 and TA2024B, it was the annoying clikpop improved, that occurs at power on and off amplifier, a characteristic of its predecessors. It was improved the efficiency (90% vs. 88%) and also power is changed, 14V against 13.2V of their predecessors.These changes cause an improvement in terms of audio playback and, last but not least, a small increase of acoustic power.
4. THE TWO-STAGE OUTPUT FILTER
In all class-D amplifiers, on the output to the speakers, a low pass filter must be used that extracts the audio information (analogue) from the PWM signal (digital). The accuracy and quality of sound reproduction depends on the type and the design of this filter.
For the LYM1.0T, we chose to adopt a two-stage filter (LC + LC). This solution, compared to the often used single stage one, can further reduce the high frequency noise coming from the PWM (Pulse With Modulation) which is based on the operation of a Class D amplifier, and improves THD + N to obtain an extremely accurate reconstruction of the audio signal.
The software simulations in the design phase and subsequent adjustments made to the circuit allowed for the best results. the accurate listening tests, performed by sound professionals, have proved the quality and excellence of this solution.
We did not use air-core coil filters because they have a high leakage flux and we could not meet the EU directive (EC 2004/108/EC) which stipulates the maximum limit for radiated noise (generators of potential interference to other nearby devices).
As a filter, we could have used the certainly better toroidal inductors, but due to the lower power of the LYM1.0T, we would not have obtained noticeable improvements, but only additional costs.
5. INTERNAL VOLTAGE REGULATOR
In an audio amplifier, the power supply circuit is what requires larger space and distance from the circuit amplification. The best solution is to move the power supply away from the audio amplifier. This reduces the classical electromagnetic interference and some problems related to its heat dissipation. Unfortunately, this leads to an increase in production costs largely due to the construction of a second device that is separate from the amplifier. However, it is important to choose the type of power supply: linear or switching. In the first case you will have a supply of superior quality but at a higher cost. Instead, using a switching power supply will cost less but it will have lower quality due to the classic ripple generated by the high-frequency switching of the active components.
In the LYM1.0T, we have opted for a circuit solution that allows you to use a switching power supply without sacrificing the benefits of a linear power supply, because in the LYM1.0T we have implemented a post-regulator that eliminates the inevitable ripple and stabilizes the voltage at the optimum value of 13.68 V.
Thanks to the stabilized post-regulator, you can feed LYM1.0T with any power supply with an output of 16/19 Vdc and deliver a current of at least 2.5A. A diode, placed immediately after the power connector, protects the amplifier from inadvertent reversals of polarity. The icon placed above the power connector indicates the correct polarity and voltage range allowed. The user can then use a simple power supply for notebooks (probably already in their possession), and thus avoid further unnecessary additional costs.
6. CAPACITORS
In the LYM1.0T, we have two types of capacitor. The first type, high-capacity electrolytic (10000μF), is placed at the output of the post-regulator. The correct sizing of this component provides an energy reserve for the power stage of the power amplifier (better dynamics). This capacitor also allows you to avoid any external power failure due, for example, to the length of the power cable and/or contact resistance of the power connector. Even an inadequate sizing of the external power supply can cause failure which, if contained, can be compensated for by the insertion of this large capacitor. The quality of power supply allows the dynamic capabilities of the TA2024C chip to be taken advantage of. A second type of capacitor has been used at the input of the TA2024C chip, after the volume circuit. This capacitor is necessary to electrically decouple the input circuit of the chip. from the sound source The high quality of this capacitor (metalized polypropylene), has allowed us to significantly reduce both the noise and the harmonic distortion which is normally produced by the presence of this necessary decoupling element.
7. “OL”: LED DI OVERLOAD
The lighting up of the Overload indicator identifies the introduction of distortions into the music playback. These distortions mainly depend on the output signal amplitude in relation to the value of power supply voltage (13.68 V) and secondarily on the RDSon parameter of the Power MOSFET inside the TA2024C chip. In fact, with the voltage required to operate the TA2024C, you cannot exceed the maximum electrical power the amplifier can provide. A 4Ω speaker with a power supply of 13.68 V cannot provide a power greater than the theoretical one given by the following formula:
Prms = (11.68V)2 / (2*4Ω) = 17.05W
where 11.68V is the voltage drop applied to the MOSFET inside the TA2024C chip when the current is maximum. In this formula, we made the hypothesis of a sinusoidal signal at 1kHz applied at the input of the amplifier and a RDSon of MOSFET equal to 0.342Ω.
Practically, in special conditions, lacking a sufficient dynamic, the amplifier performs a cut on the amplitude of the audio signal, producing a strong distortion. Being aware of the limits of operation of the chip leads the user to lower the sound volume, thus ensuring consistently optimal music listening: this is the reason which led to the introduction of the OL indicator. Another function performed by this indicator is to report an accidental short circuit at the output terminals (amplifier output or speakers input). When this happens, the amplifier is muted and the OL indicator light comes on.
In this case, the amplifier must be turned off, the cause of the short circuit must be removed and the amplifier switched on again. A similar operation also occurs when there is overheating of the TA2024C chip (>150°C), in which case you must switch off and wait for the chip's temperature to drop below 105°C before turning it on again (in our workshop, this event has never happened). This anomaly may occur if speakers with impedance lower than 4Ω are in use.
POWER SUPPLY
Now the chip Tripath is powered at 14V (while the LINE model is around 13.8V). This is the maximum power it can support, as otherwise there are more disadvantages than advantages: an increase in distortion, low efficiency and overheating.
For the power supply a simple notebook AC Adapter was used to allow customers to utilize one already in their possession (16/19 VDC with a minimum 2.5A and jack 5.5x2.5mm). For more information see the brochure "STABILIZED VOLTAGE REGULATOR”.
TWO STAGES OUTPUT FILTER
Due to the sensitivity of the PHONO circuit, we felt it appropriate replace the four coils of the first stage of the output filter, used in the LINE version only (LYM 1.0T), with excellent WURTH coils, which have a higher electromagnetic shielding. In fact the nucleus, around which the copper wire is wrapped, is made of Powered Iron Core, a special alloy that permits an improvement in the electrical parameters (for example the coil goes into saturation from 30A!).
This solution has also enabled a significant improvement in the overall quality of sound.
PHONO INPUT
This module consists of two sections: the power supply circuit and the equalization RIAA circuit. The power supply circuit is there to generate positive and negative voltages for the operational amplifiers used (LME49860). These are excellent components, by "National Semiconductor", which are characterized by high precision, low noise (2.7nV/√Hz) and low harmonic distortion (0.00003% !). The phono section is passive (without feedback). There is also a servo amplifier for nullifying the output offset. The PCB is formed by two layers: the second layer is used for electrical shielding (same technique used on the whole LYM. The input supports only MM cartridges.
NOTES
Overload Led: the lighting of the Overload Led identifies a cut (carried out by the chip) on the amplitude of the audio signal with a consequent introduction of distortion (see brochure "LED Overload"). However, these distortions, especially if short, may be inaudible.
Musical sparkles
LYD Audio have enough sparkles to ignite your little speakers and with thought out combination even bigger ones. I had no problems with discovering all the right attributes of the music with LYM Audio LYM 1.0T PHONO. I clearly shows that LYM Audio team really made their efforts to produce something better.
Conclusion
In the times where we grasp everything so quickly and so consumable its is great to see that someone took time and designed something of compact size and fair performance, pack it in really compact size and make it affordable. Surprise doesn't stops here. This is coming from Italian based company.
If you ever wanted to have an compact all in one system simple to the bones and with true audiophile blood, well here it's. It brings down the boundaries of performance, miniaturisation and cost.
I really love the addition of MM Riaa module. This brings an instant enjoyment and exploring the vast heritage of vinyl. Just connect already set turntable from Project, Rega, Clearaudio and forget about all the hassle. As written many times.... Vinyl can be fun, and LYM Audio LYM 1.0T PHONO makes this really easy to do.
Simple, straightforward products like LYM Audio brings back a positive energy and vibe to the music loving crowd and audiophiles on budget. Want to enthuse anybody not being audiophile into exploring their bellowed music whit a bit more touch? Need small or second system for your living room? Here you have a little big giant!
As I write Lyd audio There is another version called LYM 1.0T UP (upgraded - 2 line inputs) that benefits from all of the changes introduced in version phono: more power, new response curve, new two-stage filter.
The LYM 1.0T PHONO is sold through company website www.lymaudio.it at a cost of EUR 290 (320 with power supply unit) all over Europe. In Italy, the shipping cost is included in the price, while in Europe it will cost 20 euros.
Matej Isak. Mono and Stereo ultra high end audio magazine. All rights reserved. 2006-2013. www.monoandstereo.com. ..:: None of the original text, pictures, that were taken by me, links or my original files can be re-printed or used in any way without prior permission! ::..
Simple, straightforward products like LYM Audio brings back a positive energy and vibe to the music loving crowd and audiophiles on budget. Want to enthuse anybody not being audiophile into exploring their bellowed music whit a bit more touch? Need small or second system for your living room? Here you have a little big giant!
As I write Lyd audio There is another version called LYM 1.0T UP (upgraded - 2 line inputs) that benefits from all of the changes introduced in version phono: more power, new response curve, new two-stage filter.
The LYM 1.0T PHONO is sold through company website www.lymaudio.it at a cost of EUR 290 (320 with power supply unit) all over Europe. In Italy, the shipping cost is included in the price, while in Europe it will cost 20 euros.
Matej Isak. Mono and Stereo ultra high end audio magazine. All rights reserved. 2006-2013. www.monoandstereo.com. ..:: None of the original text, pictures, that were taken by me, links or my original files can be re-printed or used in any way without prior permission! ::..