Wyred 4 Sound ST500

High-end dual mono 250wpc stereo power amplifier

Wyred 4 Sound's best selling stereo power amplifier, the ST-500 offers extremely low noise and distortion – outstanding performance at an unbelievable price. Stable to 4 ohms, there are few speakers the 500's can't handle.

The ST-500 is a true dual mono design, using the same ICE based amplifier modules as high end Bel Canto and Jeff Rowland designs. The ST-500s are then modified to sound better. Modifications include extensive use of Dale resistors and Muse audiophile grade capacitors as well as other upgraded parts.

These amps also feature a custom buffered dual FET input stage designed by Bascom King. This very high quality input stage has an input impedance of 61k to work with both solid state and tube preamps.
You will find all specifications listed below, but it is worth noting that these amps have a distortion level below 0.02% and a damping factor of 2000 for tremendous woofer control.

Sonics are exceptional with superb low level resolution, exceptional transparency and tremendous bass detail and extension.

The standard ICE modules which are found in the many other amplifiers have 8K ohms on the positive input and 10K ohms on the negative input to the ICE amp. So if you’re using RCA’s, your source would be driving an 8,000 ohm load which isn’t really bad, but much harder to drive than 61.9K ohms. The lower impedance your source has to drive, the more you will experience lower volume levels, and slightly higher distortion going into your amplifier. This normally changes the way a preamp can amplify the signal applied, thus giving you less than optimal sound. Balanced amplifiers (differential, driven from + and – signals) have a much better performance when driven balanced.

All the parts used in the ST500's input buffer are of the best quality: Dale Rn55D copper leaded resistors, Wima, and MUSE audio grade capacitors, and a thick traced PCB to connect everything. Audio signal doesn’t sound as good through standard magnetic steel leaded resistors, and electrolytic capacitors. Inside the FETs on all of Wyred 4 Sound input buffers, there is a voltage to current conversion for a 'sweeter’ sound. The way a FET works is the current that flows from the output (the drain to source current) is controlled by the voltage on the input (the gate). This has a softening effect that complements the slight brightness and edgy sound of the Class D amplifier. It tends to make everything softer, smoother, and accurate. Given that the function of the amplifier, Wyred 4 Sound's input stage (buffer) has unity gain (no gain produced), and is ultra transparent.

Modifications are made to the modules in every amplifier to enhance their performance. Critical input coupling caps are bypassed to allow audio to freely flow through while still allowing for DC protection, and “beef-up” the servo (feedback) circuit for enhanced bottom-end extension. Every module is connected to the binding posts with 14AWG 99.9% OFC high strand pure copper paralleled with 14AWG high strand PURE silver wire.

One of the outstanding traits of all Wyred 4 Sound power amplifiers is exceptional imaging and soundstage rendition: uncommon in depth and height.

REVIEWS:

“I bought a 4-CH amp for use with my CS2's. It has two 250W modules and two 125W modules. I have not had a chance to hook up the CS2's with it yet as I am still scrambling to find my extra XLR cables, but I AM running the 250W modules to drive my Greybeard KB/3/3's 4ohm nominal (90dB) and 20-20Khz flat response. These things are FANTASTIC. Also, at $2495 for a 4CH amp with THAT much power, you really can't go wrong. As far as listening goes, so far, with my big Greybeards being driven by only 2CH of the amp, via the 250W modules, I am VERY impressed. Bass is thunderous and controlled. Highs sparkle with no fatigue and the noise floor is non-existent! We are driving the amp with our own tube equipment. Highly recommended!!!" – Dan W. President, ModWright Instruments Inc.

“I had opportunity to audition a Wyred 4 Sound ST-250. It is one of the best sounding solid state amps I have heard. It has detail without harshness and is not dull either. It has a rich midrange and analog sound, yet is more accurate and has less noise than tube amps. However, to me, it did not offer the full richness of a live performance like a tube amp like my Cayin can. Nor does any other solid state amp by me preferences have that 3 dimensional quality of the sound. However, with the Joule tube preamp feeding in to it, the Wyred 4 sound amp sounded remarkably good – and by my memory it bested my Musical Fidelity Nu Vista amp that I owned years ago as the Wyred seemed less fatiging and more analog sounding. I know of several people who like a hybrid tube pre with a solid state amp who gave up their tube amps for the Wyred. Considering the great price of the Wyred, less maintenace issues and the cost of tubes, and how respectably close it comes to the sound of a tube amp, it remains a tempting tube amp alternative and a wonderful first choice for a solid state amp.

The Wyred 4 Sound ST-250 sounded wonderful with my Spendors and plenty powerful. However, with the warmer sounding Zu Druid speakers the net sound seemed a little too soft to me. Interestingly, at the same preamp setting, my 45 Watt push pull tube Cayin played slightly louder than the Wyred 4 sound at the same setting. The Cayin has allot of iron and is a heavy amp and may be higher current I imagine. However, a friend of mine powers some demanding speakers very well with the Wyred.” – Audiogon forum member

“Hi, got my SX-500's Monday, hooked them up that night with my Cary SLP-03 balanced preamp (new also), let it play for one day, last night I sat down to listen and I was blown away these amps sound incredible, more detail, more depth, greater dynamic range, I swear I good tell that Ray Charles (new sacd) was sitting at his piano with his voice projecting from left to right instead of forward, big upgrade from my Krell 400xi integrated. I bought these on Walter Liederman's recommendation unheard and also since Dan Wright mentioned he liked the sound ( I have Dan's new phono stage), paid full retail and have no regrets, cant wait to listen to vinyl tonight!!!!"”

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