The chokes in this series are designed for the high-voltage power supply filtering of preamplifiers and low to medium power tube amplifiers. They are particularly well suited wherever effective filtering is required while keeping size, weight, and cost to a minimum.

The range includes models with different inductance values and current ratings to cover the most common design requirements. Each model is optimized to provide the best balance between electrical performance, compact dimensions, and ease of installation.

Due to their compact size, these chokes inevitably have a higher DC resistance than larger models with comparable specifications. In most applications this is a perfectly acceptable compromise, offset by significantly reduced size, weight, and cost.

Below you will find the technical specifications of the available models, including their mechanical dimensions, to help you select the most suitable choke for your project. The photographs are representative of the product. Minor cosmetic differences, such as wire color, paint finish, or bobbin type, may be present without affecting the electrical characteristics. A clear varnish finish is also available on request.

As with all SB-LAB products, quantity discounts are available. Ordering chokes together with power transformers, output transformers, or other products from our catalog allows you to benefit from more favorable pricing than purchasing individual items.

Mod. 23i6
	High-voltage filter choke 5H, 50mA DC, RDC 5ohm
	Dimensions (mm) L  50 H  43 S  40 F  60 F2  *

Mod. 15S60
	High-voltage filter choke 1.75H, 200mA DC, RDC 62ohm
	Dimensions (mm) L  50 H  43 S  40 F  60 F2  *

Mod. 15S55
	High-voltage filter choke 20H, 50mA DC, RDC 500ohm
	Dimensions (mm) L  50 H  43 S  40 F  60 F2  *

Mod. 15S56
	High-voltage filter choke 10H, 100mA DC, RDC 200ohm
	Dimensions (mm) L  50 H  43 S  40 F  50 F2  *

Mod. 15S57
	High-voltage filter choke 5H, 125mA DC, RDC 90ohm
	Dimensions (mm) L  50 H  43 S  40 F  60 F2  *

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Dimension Reference

The 18S100 Choke

Vacuum tube amplification has a long and fascinating history of sonic fidelity and distinctive character. Among the many key components that contribute to an immersive and detailed sound, the choke plays a fundamental role—especially when implemented in a parafeed configuration. In this context, we proudly present the 18S100 Choke, a robust and reliable component that opens new possibilities for high-quality audio enthusiasts.

The 18S100 is a high-quality choke designed to excel in tube amplification. With a nominal value of 100 Henry and the ability to handle up to 40 mA of continuous current, it stands out as a versatile and powerful element for those seeking a rich and detailed sound in their audio systems.

What Is Parafeed

Parafeed is a unique configuration in tube amplification where the choke takes on a central role as the anode load. In a triode stage loaded with an inductance in parafeed, the 18S100 Choke plays a key role in shaping the amplifier’s frequency response and linearity.

A fascinating aspect of parafeed is its direct impact on the gain of the tube stage. In particular, the gain of a triode stage loaded with an inductance in parafeed approaches the Mu value of the tube used. This connection between the tube’s intrinsic characteristics and the parafeed configuration contributes to a more accurate and controlled sound reproduction.

Practical Applications

The 18S100 Choke lends itself to a wide range of audio applications, offering an ideal anode load for tube stages that require precise DC current handling and an extended frequency response. Whether you are designing a hi-fi amplifier or a tube preamplifier, the 18S100 provides a key element for optimizing audio performance.

The versatility of the 18S100 becomes especially evident when used in preamplifier stages or as a driver stage for power tubes. Thanks to its ability to handle higher currents, the 18S100 offers an ideal option for audio projects that demand precision and flexibility in various configurations. Integrate the 18S100 into your audio designs and discover how this innovative component can elevate your listening experience to new levels of performance and satisfaction. Whether you are building a high-end preamplifier or designing a complete amplification chain, the 18S100 stands out as a reliable choice for audiophiles seeking superior sound quality.

The photographs are representative of the product, though slight variations in paint finish, wire color, or bobbin appearance may occur. Transparent varnish versions are also available. However, the general appearance and main characteristics remain consistent with what is shown in the images. In addition, all products listed are subject to quantity discounts. When purchasing inductors together with other products such as output transformers, power transformers, or any other items available on the website, you can benefit from significant savings compared to the single-unit cost, as indicated by the ratios below.

Model 18S100
	Universal Anode Load Choke, Nominal 100H (80H @ 100 Hz / 115H @ 1 kHz), Max 40 mA DC, DCR 750 ohm Test conditions with tube 6J5 (or one section of 6SN7) – Ri = 7700 ohm – bias current 5 mA – cathode bypass 220 µF – frequency response 25 Hz – 60 kHz at –3 dB. Test conditions with one section of 6BX7 – Ri = 1650 ohm – bias current 20 mA – cathode bypass 2200 µF – frequency response 20 Hz (flat) to 80 kHz at –3 dB. The choke withstands up to 40 mA DC with only a slight decrease in bandwidth. It can be used with any triode or pseudo-triode having an internal resistance (Ri) equal to or lower than 7 k ohm. With triodes or pentodes having higher Ri, a slight low-frequency attenuation may occur unless compensated by a small amount of local feedback.
	Dimensions (mm) L 63 H 77 S 86 F 50 F2 46

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Dimension diagram

This component, available in two versions, 17S71 with single winding and 17S71B with split winding, represents a powerful upgrade for audiophiles seeking superior audio performance.

Outstanding Features:

1. 10mH Value: With an inductance of 10mH, this component provides effective filament power supply filtering, ensuring a crystal-clear and noise-free sound.

2. Current up to 3.5A: Supports currents up to 3.5A, ideal for powerful tubes such as 2A3, 300B, 845 and 211, offering unprecedented stability and power.

3. DC Resistance of 195 milliohm: The total DC resistance value of 195 milliohm ensures optimal conductivity, helping to maintain sound clarity.

4. Different Versions: Choose the 17S71 with single winding for traditional filtering, or the 17S71B with split winding for common-mode filtering, ensuring flexibility in applications.

Versatile Applications:

This choke is not only a powerful component for high-grade tubes. Its versatile applications include:

• Powerful Audio Tubes: Optimizes the filament supply for tubes such as 2A3, 300B, 845 and 211.
• Advanced Filtering: Perfect for high-gain audio applications, ensuring advanced filtering and superior audio quality.

The photographs are representative of the product, although slight variations may occur in paint quality, wire color, or bobbin appearance. Transparent coating is also available. However, the general appearance and main features are consistent with what is shown in the images. In addition, all items listed are subject to quantity discounts. By purchasing chokes together with other products such as output transformers, power transformers, or any other items available on the site, you can benefit from significant savings compared to the unit cost, as indicated in the proportions below.

Model 17S71 – 17S71B
	Universal filament filter choke for directly heated tubes (2A3/300B/etc.) 10mH, max 3.5A DC, RDC 0.195ohm
	Dimensions (mm) L 63 H 77 S 86 F 50 F2 46

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Dimensions caption