from the 1959 Heathtkit catalog:
High Fidelity
25 Watt Amplifier
Still a favorite in its power class, the W-5M represents one of the most outstanding high fidelity amplifiers available today at any price. It employs a specially designed Peerless output transformer and KT66 tubes to prevent loss of frequency response particularly at moderate volume levels, in addition to allowing increased power output. The circuit is rated at 25 watts and will follow instantaneous power peaks of a full orchestra up to 42 watts. Also featured is a "tweeter saver" which suppresses high frequency oscillation, and an easy-to-adjust balancing circuit to obtain "dynamic" balance between output tubes. In order to reduce harmonic distortion at low frequencies it is essential that the plate current of the output tubes be balanced. The exclusive balancing circuit in the W-5M makes this balancing operation easier and much more accurate. Precision balanced resistors are connected in the cathode circuits of the power output tubes. When the current in each tube is balanced, the voltage drop across each precision resistor will be the same as the resultant potential will be if measured at both cathodes at the same time. A great advantage is gained, since the current in both tubes is measured simultaneously instead of one at a time and only a voltmeter is required. A load limiting device is built into the amplifier to provide high frequency and transient stability. Rising impedance affects of speaker systems at higher frequencies will frequently cause oscillation in a feedback type amplifier, since the amplifier fails to match the load at these frequencies. To counteract this, a resistor and condenser have been installed in series across the output transformer secondary. The condenser is chosen to prevent loading of the amplifier throughout the audible portion of the spectrum and still provide loading above these frequencies. Results of this unique circuit arrangement add up to improved phase shift characteristics, reduced IM and harmonic distortion and improved frequency response with complete stability under all dynamic operating conditions. All connectors and terminals are conveniently located on one side of the chassis apron. The circuit is fused, and two AC outlets are provided for accessory equipment. One outlet is switch-operated and can be used to automatically turn off record player motor when amplifier is turned off. Provision is made for matching 4, 8 or 16 ohm speakers at a terminal strip on the chassis. An attractive cover protects against tube breakage and accidental burns. The bottom plate has large rubber feet to prevent marring of furniture. Featuring stylish gold and black color harmony, the amplifier is suitable for built-in locations or as a bookshelf model. Conservatively rated, high quality components are used throughout to insure years of trouble-free performance. Easy to build and a thrill to use. Shipped express only. Shpg. Wt. 31 lbs.
Specifications
Power output........................ 25 Watts
Frequency Response.................. +/-1db for 5 to 160,000
cps at 1 watt
Harmonic Distortion................. 1% at 25 watts
Intermodulation Distortion.......... 1% at 20 watts (60 and
3,000 cps)
Hum................................. 99 dB below 25 watts
Damping Factor...................... 40:1
Input voltage for 5 watts output.... 1 volt
Tube Complement..................... 2-12AU7, 2-KT66, 1-5R4GT
Output Transformer.................. Peerless Special Design
Power Requirement................... 105-125 volts, 50/60 cycles,
140 watts
Dimensions.......................... 13 1/8" wide x 8 1/2" deep
x 8 1/4" high
Shipping Wt......................... 31 lbs
Specifications, from the Manual....
Rated Power......................... 25 watts
Maximum average Power............... 32.5 watts
Peak Power.......................... 47.2 watts
Hum and Noise....................... 80.2 dB below 250 milliwatts, unweighted. (General average listening level.), 84.2 dB below 5 watts, unweighted. (Loud average listening level.), 99 dB below 25 watts, unweighted.
Feedback Factor..................... 18.1 dB of feedback is applied around entire amplifier and output transformer.
Output Impedances................... 4, 8 or 16 ohms, unbalanced.
Small Output Transformer............. Peerless 16309
Large Output Transformer............. Peerless 16458
Power Transformer.................... Heath p/n 54-32
Choke................................ 7H 150 mA, Heath p/n 46-12
The Heathkit W-5M Amplifier, a "standard" in our audio amplifier kit line for many years, has been discontinued. Style changes and new concepts in circuit design plus the increased trend towards stereo, contributed to the discontinuance of the W-5M. During the production of the W-5M, a few minor changes were made in its circuitry to improve its performance. These changes are listed below:
Page 19, Step 12 - Change "15k ohm, 1 watt reststor (medium body, brown-green-orange)" to "15k ohm, 2watt reststor (large body, brown-green-orange)" R-28.
Page 19, Step 13 - Change "6.8k ohm, 2 watt reststor (large body, blue-grey-red)" to "15k ohm, 2 watt reststor (large body, brown-green-orange)" R-30.
Page 20, Step 12 - Change "22k ohm, 1/2 watt reststor (small body, red-red-orange)" to "22k ohm, 1 watt matched pair of reststors (medium body, red-red-orange)" R-10.
Page 20, Step 13 - Change "22k ohm, 1/2 watt reststor (small body, red-red-orange)" to "remaining 22k ohm, 1 watt matched pair of reststors (medium body, red-red-orange)" R-9.
Page 21, Step 1 - Change "47k ohm, 1 watt reststor (medium body, yellow-violet-orange)" to "47k ohm, 2watt reststor (large body, yellow-violet-orange)" R-8.
Also a Surgistor was added to limit the high voltage surge that may occur when the amplifier is first turned on. This will help prolong the life of the components used in the amplifier, where line voltage or transformer voltages may be somewhat higher than normal but still within their rated specifications. An information sheet regarding the installation of the Surgistor is enclosed with this component.
Peerless 16309 Output Transformer
Subject: Re: Tranny help
From: "Michael
S. LaFevre" <[email protected]>
Date: 1996/10/03
Message-Id: <[email protected]>
References: <[email protected]>
Newsgroups: rec.audio.tubes
David Home wrote:
>
> I have two Peerless 16309s. Could someone tell me something about
them?
> Primary impedance, Q-factor, Symetrical secondary? Thinking of using
them
> with EL34s PP. Thanks.
The 16309 was originally designed on 2\10\55 by Ercel B Harrison and
was
used on the Heath W5 amplifier.
Primary impedance is 10K CT with 50% screen taps.
secindaries are 16, 9, & 4 ohms. they are single ended and hence
not
symmetrical.
quality factor is not specifically called out for in the blueprint or
the testing procedure but it would be quite high...probably circa
100,000.
Mike LaFevre
Peerless 16458 Output Transformer
Subject: Re: Output transformer identification
Date: 3 Jul 1997 08:06:11 GMT
From: [email protected] (AirGapped)
Organization: AOL http://www.aol.com
Newsgroups: rec.audio.tubes
William Bittle wrote:
> > Hi All, I have a Peerless Electrical Products output transformer
that I could use a bit of help with. It is made by Altec Lansing, is an
"Ultra Linear" type, and has a model number of: 16458. It is roughly the
size and shape of an Acro T0-300. What I am wondering is if anyone knows
what the plate to plate impedance of this transformer is and what sort
of power it is rated for. On the output side it has the standard color
coded wires for 4,8, and 16 ohm taps. Thanks, Bill B.
The 16458 was originally designed for the Heath W5M amplifier (Heath part # 51-19) by E.B. Harrison on 5-27-57. It has a 10K ohm load with 50% screen taps. Power rating is 25 watts at 20 cycles per second. FR was tested at +/- 1db from 10 hz to 75 khz.
Mike LaFevre Peerless\MagneQuest
This page last updated on November 29, 1998
