30-year-old Panor-era Dynaco ST-200 Power Amp loses Left Channel. Meet the B&K Components ST1400 Replacement Amp!

 September 11, 2024

#495

Gentle reader,

Like December 7th, 1941, September 11th, 2001 is "a date which will live in infamy". For that matter, so has January 6th, 2021 joined that terrible days for the USA, list.

But, enough about that! I last wrote about a new-to-me piece of audio equipment here: The Robb Collections: Right Time, Right Place I Found a Working 45 year old Nakamichi Cassette Deck!  That dealt with the stack of equipment to the right of the PC's 27" monitor which I am writing this onto in "the office". It's a bedroom we designated in 2001 before we moved in, for a home office for both of us. It has morphed into mostly mine and I spend a good deal of time in here.

Anyway, when listening to music in the listening room which was the "master" bedroom (I understand we are not supposed to use that word anymore) when the house was new in 1987. But, the original owner finished the lower level creating a much larger bedroom.) the other day, I noticed that the left channel was suddenly silent! 

This is the most recent image I have made of the majority of the room. Camera: Nikon D300, lens: Sigma 10-20mm. Shot at 10mm. Below is the most recent image of the entire system, taken a few months earlier. It is the culmination of almost fifty years of trying and buying hundreds (90+% used) components and speakers. Thanks to a thriving "previously enjoyed" audio equipment market, I had been able to finally afford to buy 1990's Panor-era Dynaco equipment. Specifically, in order of purchase: ST-200 100WPC power amplifier, QD-2 "FIVE CHANNEL HOME THEATER SYSTEM" their reinterpretation of the original 1970's Dyna-quad device. And, latest of all purchase being their solid state PAT-6 preamp/tuner. 

All has worked well for many years. Since I retired, I have been slowly working my way through the 3,000+ recordings and listening to them all. So, the system has been getting a lot of use.

The ST-200 power amp upon the top shelf of the equipment shelf. The PROTON preamp which I was using at that time, sits on the shelf below. Some years ago, the left channel of the ST-200 was cutting out. I correctly surmised that it was overheating. Thus, the "muffin" fan atop it to keep the left power transistors cool. I later bought a dual fan which sat atop the entire opening of the top cover.

The interior of the ST-200. By the way, the ST-400's insides are quite different than the -200. The same chassis is used for the ST-100, but I have never seen one.

So, what could be wrong? I have no idea. My friend, Bob Berne, may have an idea as he used to be in the business of repairing stereo equipment. It's thirty years old, I certainly got my moneys worth out of it. I will hang onto it for a while.

This is the information which Dynaco sent me back in the 1990's. I should have scanned it all. But, at the time, I (incorrectly) figured that I would never be able to afford anything more than a QD device and sold the lot on eBay.

Above is a scan of one of the three pages of Orion Blue Book Audio equipment. Each highlighted line is something I have owned. Note that the ST-400 Series II cost nearly twice as much as the ST-200 did, when new.

Bob has a Panor-era ST-400 Series II power amp and I have seen them for somewhat reasonable prices over the years. I had an original ST-400 as seen in this image (below) from 2007, when the listening room was still a bedroom. The surface they are sitting on is the top of a shelf I made fifty years ago out of white walnut.

I designed it to fit rack-mount equipment (thus 19 inches wide) but, I have never owned any. This image is from 2005. Much has changed since then!

However, the Panor-era ST-400 Series II has only one set of speaker terminals. I got used to being able to switch between front A speakers (large black Cerwin-Vega! LS-12 speakers) or the Dynaco A-25XL speakers and back speakers being a pair of Tannoy C88 tower speakers driven through the QD-2.

This image is a little older than the one at the top of the article. You can see the Tannoy speakers a little better. The 8mm fisheye lens makes it look like they are angled, they are not. Whew! With all that being said, we move to the present.

So, I did as I usually do, went on to eBay looking for a replacement power amplifier. Nothing Dynaco which was not from the last Millennium, so that was out. I began looking at other brands. This black beast caught my eye. 

Back when I was still working a actual paper magazines were still being made, I subscribed to Stereophile and The Absolute Sound magazines (and others before they folded) so, I recognized B&K Components Limited as being an American company.

I "did my own research" and found glowing reviews of B&K products in general and this power amp, specifically. So, I bit and bought this one.

Huge power capacitors and a toroidal power transformer showed it to be well designed. 

They were smart in making their chassis to house more powerful components. More on that later.

The amp included a print of the owner's manual and a power cable. The manual turned out to be for a Series II, but the specs are the same and the main difference is the back panel. The cable was thin, and I already am using Pangea AC-9 power cables.

Below is a photo of it in place of the original Dynaco ST-400.

Below is a "before" image so that you can see what I had to do to shoehorn the heavy amp in place.

The arrangement of the inputs and speaker terminals required it to be shifted to the left. 

The Realistic APM-300 LED power meter not sits atop the QD-2. I have it set at 4 ohms since I now run all four speakers all the time.

The contraption (above) to the left of the turntable is an inexpensive (3-way binding/banana post) speaker switch which I used to switch the meter's input signals depending upon which set of speakers (C-V LS-12 or A25XL + C-88 rears) I was listening to.

Here is an overhead shot of the stack. The switch is very lightweight, so I added two steel weights to the front of it to offset the weight of the speaker cables. The purple dual-banana plugs are ones I found in the trash at work decades ago. The switch is no longer needed, as I am letting the Dynaco A-25XL speakers rest for a while. They are from the 1970's and likely need new crossover capacitors.

B&K Components Limited went out of business in 2010. As a result, there was no longer a website to look things up on about their products. I DID find images (all below, found on the Internet) of related power amplifiers. Their amplifier nomenclature is to me somewhat confusing. I avoided "Series II" units in order to find these images. 

This is the ST1430 which is their three-channel (center channel speaker) version. I suspect that there was an additional, albeit smaller, heatsink and power transistors plus other components inside it.

The rear of a ST1430.

Above and below are images of the ST1400's big 200WPC brother, the ST3030. 

The rear is virtually unchanged from the ST1400.

However, despite the -30 in the ST3030 name, it is only a two channel, not three channel amplifier. Note the addition of a second set of power transistors and heatsinks in this very expensive and no doubt much heavier beast.

So, now, I suspect you may be thinking, "So, how does it sound?" It a word, fantastic! The soundstage has not only widened it is halfway into the room now! Partly, that is because of the Tannoy C-88 speakers right behind me. The music is so much more robust and I am truly sold on B&K Components equipment! 

Does this mean that I am now looking for a matching preamplifier? Maybe. There is nothing wrong with the Dynaco PAT-6. I don't really use the tuner, and could use more inputs, but, so far, it is working and sounding fine. Plus, it is the first preamplifier I have ever owned which has a remote control! So, there's that. 

Thank you SO much for taking the time to read this rather lengthy article. It is my 495th one so far. When I started blogging all those years ago, it was just something to do. I have NO idea that folks would like what I write. But, you do! And I cannot thank you enough. 

Feel free to comment below or via Facebook. 

Scott Robb

September 11, 2024

#495