Chill-amp

Description: Experimenting with gainclone amplifiers. Gainclone amplifiers utilize operational amplifiers (op-amps) instead of the tubes and transistors commonly found in most amplifiers. This document presents the second iteration of the Chill-amp concept. The interest in exploring op-amps originated from positive reviews of the Gaincard by 47 Labs and the article "Op-amps are More Fun than Tubes." Subsequently, various gaincard clones, known as gainclones, were discovered, including a forum dedicated to building amplifiers with op-amps, the Amp Chip DIY Forum. An interesting circuit design by Thorsten Loesch, an inverting gainclone, inspired the creation of the first amplifier, the Thor-amp, which produced a pleasing sound. However, limitations were noted, leading to the exploration of a non-inverting op-amp circuit, which was found to have superior performance in certain aspects and was named the Chill-amp. The popularity of gainclones surged on Diyaudio, particularly following a thread showcasing Peter Daniel's aesthetically pleasing casework. The development of the second version of the Chill-amp took longer than anticipated due to various challenges, but the improvements in sound quality over the first version justified its release. The Chill-amp II aims to enhance performance in detail, imaging, dynamics, and instrument realism while ensuring compatibility with a diverse range of music. A significant upgrade from the first version is the power supply, which now employs two transformers per channel, reducing the number of diodes required and enhancing the speed and linearity of the supply. Dual Schottky diodes, STPS20H100CT, are utilized, with only two needed per channel. A 50k stepped attenuator from DiyFidelity, featuring 23 steps, is implemented for volume control, providing a wide range while maintaining sound quality at an affordable price. The Chill-amp II is optimized for high-efficiency speakers (>90 dB/W) with an 8-ohm impedance and is not suitable for speakers with an impedance below 4 ohms. The amplifier delivers approximately 40W and is currently paired with Supravox 215 Signature Bicone full-range speakers in open-baffle configurations. Additional information on these speakers will be provided. The interior of the Chill-amp II is documented with photos, and earlier beta versions are also available for viewing. The Chill-amp II employs printed circuit boards (PCBs) for several reasons: ease and speed of assembly, improved solder connections (especially for ground wires), enhanced rigidity of component mounting to reduce the impact of vibrations on sound quality, increased channel matching, and overall robustness. While the supply PCB is more suited for the Chill-amp I, it is compatible with the Chill-amp II as well. The cost of the amplifier PCBs is EUR 10.00 per pair, while the supply PCBs are EUR 12.00. A set of four PCBs is available for EUR 20.00, with international shipping costing EUR 5.00. For further inquiries, please reach out via email. A stock of block transformers has been acquired for use in the Chill-amp II, featuring a 220V primary and an 18-0-18V secondary, sourced from the late 1970s. These transformers are likely rated between 40-60 VAC, sufficient for a gainclone configuration when four are employed. They are priced at EUR 32.00 for four, excluding shipping, and are only available in conjunction with the purchase of Chill-amp PCBs.

The Chill-amp II amplifier design focuses on utilizing operational amplifiers to create a high-performance audio amplifier that is user-friendly and adaptable to various audio setups. The choice of components, particularly the use of dual Schottky diodes and a stepped attenuator, reflects a commitment to achieving superior sound quality while maintaining affordability. The design philosophy emphasizes the importance of speaker compatibility, advocating for high-efficiency speakers to maximize the amplifier's performance. The implementation of PCBs not only simplifies the construction process but also enhances the overall durability and sound quality of the amplifier by minimizing potential noise and interference from external sources. The use of high-quality transformers ensures that the power supply can deliver stable and reliable performance, which is critical for high-fidelity audio applications. The Chill-amp II represents a thoughtful evolution of the original Chill-amp, addressing previous limitations and enhancing the listening experience for a wide range of musical genres. The careful selection of materials and components, along with the innovative design, positions the Chill-amp II as a compelling option for audio enthusiasts seeking to explore the potential of gainclone amplifiers.Experimenting with `gainclone` amplifiers. Gainclone amplifiers use opamps instead of the tubes and transistors that can be found in most amplifiers. I now present the second reincarnation of the Chill-amp concept. My interest in trying something with opamps was born when I saw the raving reviews of the Gainc ard of 47 Labs and the article "Op-amps are More Fun than Tubes". Soon, I found some pages describing various clones of the gaincard (called gainclones). The most interesting was a forum dedicated to making amplifiers with opamps, the Amp Chip DIY Forum. I found an interesting circuit made by Thorsten Loesch there, an inverting gainclone. With this circuit, I made my first amplifier, the Thor-amp. That amplifier sounded quite sweet and for a long time I was quite happy with the result! I found some limitations. I tried the non-inverted After a while, opamp circuit, and found it to be superior to the inverted circuit in some ways. I called it the Chill-amp. Meanwhile, on Diyaudio a gainclone rage was born, especially after the gainclone thread with beautiful casework of Peter Daniel.

Finishing the second version of the Chill-amp took longer than expected due to various reasons. There are still some things to be tried out, but I think that the difference in sound over the first version is worthy of a release. The target of the Chill-amp II was to raise the bar further in performance (detail, imaging, dynamics, instrument realism etc.

) while maintaining a good listenability with a wide range of material. Ultimately, I built this amplifier to enjoy all kinds of music, not to listen to some obscure audiophile labels only. The biggest difference compare to the Chill-amp I is in the supply. The supply makes use of two transformer per channel. This way, less diodes are necessary. This improves the speed and linearity of the supply. I use STPS20H100CT dual schottky diodes. These are very practical because only two are necessary per channel. I now use a 50k stepped attenuator from DiyFidelity. It has 23 steps, which is more than enough for a good range in volume. The attenuator sounds great, and is very affordable. A very important topic regarding chip amplifiers is the choice of speakers. The Chill-amp II can be best used on high efficiency speakers (>90 dB/W). Also, speakers with an impedance of 8 ohm are better suited. This amplifier is not so suitable for speakers with an impedance under 4 ohm. The Chill-amp II delivers about 40W. I currently use the Chill-amp II with Supravox 215 Signature Bicone full-range speakers in open-baffles.

Very recommendable! More information will follow about these speakers. Here is a photo of the interior of the Chill-amp II: click me!. Furthermore, here you can find some photos of an earlier version of the Chill-amp II: Chill-amp II beta photos The Chill-amp II makes use of PCB`s. This done for multiple reasons. The first reason is that it makes the amplifier much easier and faster to build. It is easier to make good solder connections, especially for the ground wires! The components are mounted more rigid, thus vibrations will have less influence on the sound. Also, the two channels are more identical. Finally, the robustness is somewhat improved. (and it even looks better IMHO!) The supply PCB is more suitable for the Chill-amp I, but can be used for the Chill-amp II too.

The amplifier PCB`s cost only EUR 10, 00 for a pair, the supply PCB`s EUR 12, 00. Four PCB`s cost EUR 20, - International shipping is 5 euro. Mail me for more information! I bought a stock of block transformers to be used in the Chill-amp II. The transformers are 220 V primary, 18-0-18 V secondary, NOS from the late seventies. They are probably between 40-60 VAC; enough for a gainclone if four are used. The transformers are available for only EUR 32, 00 for four! (excluding posting, only in combination with Chill-amp PCBs). I