Reliving the 1976 sound of Dynaco PAT-5 preamplifier and SWTPC power amplifier!

Gentle reader,

Thanks to the world's largest flea market, otherwise known as eBay, I have been gathering vintage stereo components to recreate my very first stereo I built from kits in 1976 when I was 19-20 years old.

I had bought 32 year old Klipsch KG-4 speakers at a thrift shop and seeing all this vintage equipment people are enjoying in the various FaceBook groups I belong to, AND seeing all the awesome vintage equipment at HiFi Heaven in northern Virginia, I really wanted to experience that "vintage sound".

I first wrote about it here:

BACK to: My First Stereo 1976 Dynaco PAT-5 SWTPC Tiger 01  and also showed photos of various Dynaco equipment I have owned since having a digital camera, here:

Dynaco, the Legendary American Audio equipment company.

The original Dynaco PAT-5 preamplifier that I built as a kit was a bit newer than the one you are about to see. The faceplate was not gold-hued like so much Dynaco equipment of yore. And the PAIR of Southwest Technical Products Corporation 60 watt mono amplifiers I built after completing the PAT-5 are long gone. They stopped working and eventually I gave them to a coworker. 

I have bought, enjoyed and passed on to others countless pieces of stereo equipment over the decades since 1976. Not buying my first CD player, a used early model one, until 1996. I bought it only because I could not find a certain Jazz album on cassette. But I digress.

So, I have these Klipsch speakers from 1985 and a LUXMAN turntable from I don't know when and really no where to put them all together! Oh, and I am also acquiring a pair of my very first speakers too: Dynaco A-25s. I just bought one via eBay for a great price and will eventually find a mate for it.

So, here we have my latest PAT-5. Got it for $99 via eBay. Was told it works and it does. Aside it is NOT a SWTPC 207 Tiger .01 60 watt mono power amplifier, but a later model called 215. It uses a smaller (lighter) transformer and smaller less powerful power transistors all enclosed in what normally houses just one Tiger mono amp. It puts out 25 watts per channel and uses the same circuitry as it's big brother seen below in a scan from the original instructions:

 

Below is the same company information sheet for the smaller, yet stereo amplifier:

 I have periodically looked for SWTPC equipment on eBay but they were always listed as not working. To my delight, I saw the 215 listed as working at $60 or best offer. So, I offered $50 and the seller accepted it! 

Here is a photo of my original PAT-5 that I sold once one channel stopped working. See the differences in the faceplate?

Someone in the past replaced the power switch with a light, above.

Seeing the insides of this PAT-5 brought it all back to me all the work it took to complete it.

I came across this photo I made some years ago of the inside of a modified PAT-5. It was NOT a Van Alstine mod, but the eBay buyers recognized the name of the man who did the work.

Quite a number of changes now that I have a stock unit to compare it too!

The seller of the 215 power amp showed photos of the inside and they were accurate! Here are my photos once I got the cover off.

It's a very strange dust, the color and texture. Below are the "after" photos:

As you can see, although the dust is gone, corrosion and even rust on a steel piece that runs between the circuit boards, abounds. I cleaned metal bits with Dylek contact cleaner and DeToxit too. I found one wire had broken off and located where it attached to one of the big capacitors. Other than that, it all seems whole.

Below is a photo of a Tiger amp's rear panel. The heatsink shown above is used throughout the entire SWTPC audio line, even the amazing TIGERSAURUS 200 watt mono amps. The Tiger uses two sandwiched with T03 type transistors.

Above photo was found via a Google image search. I could not find any photos of the inside of a Tiger to show you.
Quite a bit different, aren't they? All the fuses are inside the 215. Note the normal RCA inputs, but 1/4" mono plugs for the speaker cables. I had to buy a pair of professional speaker cables which had the 1/4" plugs on one end and dual banana plugs on the other end via eBay:

As I discovered some time ago, the standard 3/4" spacing for banana plugs as seen on the PAT-5 and many speakers isn't followed anymore. So, I replaced those that came with these Seismic Audio cables with the ones seen above.

Another Google image search netted me these fine images of the inside of a very pristine 215 power amplifier.  Yet despite the age, this thing is working perfectly!

Note the board atop the big capacitors is vertical as were the ones in my Tigers.

I suspect this amplifier was factory wired, where the one I have clearly was not! Yet, after forty-some years, it and the PAT-5 are still rocking away!

Yes! Even the meters still work!

I've only played CDs so far via the SONY WALKMAN portable player.

First Dynaco A-25 speaker has arrived. Amazing condition. It is the "VW" model which means vinyl instead of real walnut veneers. Am now searching for a matching one. I always play my music with the grilles off.

  

I came across the idea of wall mounting a shelf to hold the Luxman turntable. There are many available ( for a fraction of the cost of a "real" shelf to hold a turntable!) but I wanted one made of real wood, not particle board. Bot this via Amazon. Very well made. Now, where to put it!

Stay tuned for an update once it is all located and when I have two A-25 Dynaco speakers too!

Thanks for looking!

Scott