Threshold400AThreshold 400A power amplifierThis listing is for a Threshold 400A power amplifier in overall good condition, a few scuffs on the edges and rack handles (pictured). A 1978 model by the serial number. It came to us with a bad ch...699.00

Threshold 400A power amplifier [Expired]

no longer for sale

This listing is for a Threshold 400A power amplifier in overall good condition, a few scuffs on the edges and rack handles (pictured). A 1978 model by the serial number. It came to us with a bad channel, we replaced 4 output transistors to make it work correctly again. It has been here waiting for the customer to pick it up for over 2 years now and has been released to sell, he will not be picking it up. It was not completely rebuilt, just made to work again. It has not been in use for a long time until now.

We guarantee it to work correctly upon arrival and for 30 days from ship date.

Threshold 400A

A two Channel audio power amplifier employing patented dynamic bias circuits that maintain the amplifier in Class A operation to beyond 500 watt transient output levels per channel.

Rated Power:
100 watts per channel, both channels driven into 8 ohms, 20 Hz through 20 kHz at 120 volt line source.

Harmonic and Inter-modulation Distortion:
No greater than 1 percent total harmonic or intermodulation distortion at rated power, decreasing monotonically with lower power. Distortion virtually unmeasurable at small signal levels. Harmonic distortion components are dominated by 2nd and 3rd harmonics. Intermodulation sidebands are primarily 1st and 2nd order. Distortion components of higher orders are negligible below 40 kHz.

Transient Intermodulation Distortion:
Transient intermodulation distortion sidebands are at least -75dB below a 10 watt output signal consisting of a 1.5 kHz sine wave linearly mixed with a -20 dB 80 kHz sine wave, the sidebands are symmetric about the central frequency decreasing to approximately -90 dB by the seventh order.

Rise Time:
Leading and trailing edge 1 microsecond.

Slew Capabilities:
Maximum voltage slewing rate each channel 50 volts per microsecond. Maximum current slewing rate each channel 25 amps per microsecond.

Loop Propagation Time:
Propagation delay appearing at the bases of the input differential transistors 20 microseconds.

Current Output Capability:
Maximum instantaneous output current capability 20 amps per channel. Maximum continuous output current capability 5 amps per channel.

Voltage Output Capability:
Maximum voltage swing -+ 50 volts per channel.

Frequency Bandwidth:
+0,-3 dB 1 Hz through 250 kHz at small signal levels. -+0 dB 20 Hz through 20 kHz at 200 watts per channel.

Input Impedance:
75 kohms

Damping Factor:
Constant 100 from dc through 20 kHz measured at output terminals

Hum and Noise:
.5 millivolts at the outputs.

Individual peak vs average output level readings for each channel.

produced and built from 1977 to 1981.

Underrated as an 7 for buyer satisfaction.

Guaranteed to arrive intact, and to be as described.

Offered for $699.00, pls add 2% if using Paypal or credit cards. Bank wire and Paypal only outside the US. Always carefully packed and promptly shipped.

We can be reached at (352) 378-0192 ext 307 or ask for Rob


Revised shipping policy as of September 20, 2005.

Due to items lost or damaged in shipping, any item over $50.00 in cost will require delivery confirmation and insurance for the sale amount. It is unfortunate that this is necessary but experience has proven it is well worth the small extra cost. We apologize for this, but it is for the good of all involved.

Our reputation is very important to us. If you would like to check our eBay feedback rating you will find over 2000 satisfactory transactions with no negative results. We still maintain a 100% positive feedback rating. soundideasflorida is our user name.

TERMS: All listings are plus shipping unless noted. 6.25% sales tax added to all In-Florida destinations. This unit is guaranteed to be in "as described" working condition (unless otherwise noted) upon arrival and has a 30 day limited warranty, baring any abuse. 15% restocking fee on all returns unless defective or "not as described"

PAYMENT or payment notification expected within 48 hrs of invoicing. We accept PayPal, credit cards, money orders, international money orders, cash if local p/u. Money orders, international money orders, etc, must clear before shipment.

SHIPPING: We ship internationally on smaller items . Domestic packages are shipped via Fed Ex. Small items (such as vacuum tubes) or international packages shipped via USPS. All shipping quotes will include insurance and delivery confirmation. Shipping charges reflect actual cost of shipping, plus a nominal fee for packaging materials. Items are very carefully packaged for shipment. Items ship from 32609 in Florida.

INSURANCE: International shipments to countries that do not allow insurance, buyer assumes FULL RESPONSIBILITY for the safe shipment of their packages. Sound Ideas cannot provide refunds or compensation for packages shipped without shipping insurance. All shipping quotes for packages shipped includes insurance.

RETURNS: Any item may be returned within 15 days for a full refund of the purchase price, not including shipping and restocking fee, unless otherwise stated in the ad. It must arrive back at our store in Florida in the same condition as sent. International purchases need to be returned with incoming custom's duty prepaid, if any. Any postage or import duty that is due upon arrival will be deducted from the refund. 15% restocking fee on all returns unless defective or "not as described."

CONTACT: We stock over 50,000 vacuum tubes. Contact us if you have any special vacuum tube needs.
Sound Ideas,
3215 NW 13th Street,
Gainesville, FL 32609.
352-378-0192(9 am-6pm Monday-Friday,10 am-5pm Saturday, EST)
Since 1977.We carry over 50 new brands of electronics, please stop by the store when you are in Florida.

Rob - Internet Sales Manager
Mon-Fri 9am-6pm
Please feel free to e-mail me: ""
Sound Ideas - Gainesville, Florida
Tel: 352-378-0192
Fax: 352-371-1791

Thank-you for your time and interest!
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