UPDATE Inexpensive Chinese-Made TUBE BUFFER amplifiers. A Review of One using 6J1 Tubes Upgraded to GE JAN 5654W Tubes

 March 18, 2024

#476

UPDATE!

Gentle reader,

It has been a VERY long time since I have written anything about the listening room stereo. I have (after more than forty years) been very happy with the system and thus stopped trying to improve it.

Over the years of which I have been writing this blog, several of my readers have reached out to me via Facebook and we have become Facebook friends. Of them one lives within reasonable driving distance and we have gotten together a couple times. Another lives in the same town my Aunt does in Arizona. So, someday we will actually meet, when we finally go out there for vacation. We talk frequently by phone and both are dear to me.  In the mean time, these two and I have come to call ourselves The Three Amigos. Which is the title of a comedy film starring Chevy Chase, Steve Martin and Martin Short.

One of them, who has a Dynaco Museum in his home, last year came up with the idea of all three of us building a small Chinese-made tube buffer amplifier. 

The one in Arizona had these guitar pick holders custom made for the three made up for all of us and surprised the other two with them. He is a very giving person.

This is what the kit is comprised of and the parts list for it. 

This is the schematic.

This image is from an eBay seller called Yunsirui. What was NOT included with our kits was the clear plastic housing (shown with protective paper covering), switch knob or 12 VAC "wall wart" power transformer.

Sadly, none of us got around to actually building the kits! No excuses. I did provide four 12 VAC transformers and knobs (two for me, more on that later) to all of us. The transformers are for landline telephones. See below.

Note the 4.17 AMP (50VA) specification. Talk about potential GAIN!

The transformers are large and heavy, which makes sense since they have lots of potential power.

I went ahead and bought two prebuilt ones via eBay, just in case I failed at building them. The first time any of you saw the first one was here:

The Robb Collections: UPDATE on Review of SKW Cables "Audiophile" at Bargain Prices? Amazon Exclusive SKW Cables

Never one to leave well enough alone, I bought two "Audiophile Grade" 6J1 tubes which are shown below. I do NOT have golden ears and could not tell any difference between the factory supplied tubes and these.

For many months I have enjoyed this little tube buffer in my "home office" with a vintage all-Yamaha stereo stack and an OPPO universal player. No room to use a turntable with it. The stack sits inches from me. Initially, I had the buffer atop the OPPO. I used QUAKEHOLD reusable adhesive putty to hold it in place since the unit has no feet and the pull of the cables would surely snatch it off the top.

I have had zero problems with the little unit and since I have no idea what "Warmth" means as far as the sound of music, I can only say that it does sound a bit nicer than before. Plus, the gain the transformer provides can really crank out some volume. My neighbors, who put up with my occasionally loud music would draw the line should I decide to see JUST how much louder it could get.

I finally decided to assemble the second eBay-purchased board in the case, etcetera. Prior to doing so, I was looking at other similar (all likely Chinese-made) tube buffers on offer out there.  

To my dismay, the second buffer I already had, produced barely any volume from the right channel! I looked at the board and it's components and it was easy to see that the volume control had been replaced. Since I'd bought it from a Chinese vendor on eBay a while back, I set out to find a replacement from a USA vendor. And did so for just over $13.00 with free shipping.

Being curious, because some vendors offered "upgraded" tubes for additional money, I decided to see what are considered the "best" seven-pin tubes. Here are two sites I looked on to learn more:

electron Tube Data sheets - 6 and 7-Pin Vacuum Tubes 5654W Upgrade – 6AK5 6J1 6J1P EF95 6k4 – Fosi Audio

The latter stated that vintage General Electric JAN 5654W Tubes were the best, but due to demand, are getting harder to find and thus, pricy. I found a pair on Amazon for way less than those being hawked on eBay.

According to the labels, they were made in July, 1987. Which qualifies as vintage by any metric.

The seller wrote:

• Built to the TOUGHEST USA standards for Amplifier.
• JAN 5654W Made by General Electric USA, Higher Durability and Life, Heavy Duty Cycle Military Specification Grade (JAN) , Considered one of the best of the 5654 family of tubes for audio use. Large ring, enhanced mica, green powder word + matte word mark.
• The sound is full, soft, delicate and poisonous, (?) larger soundstage, Treble and bass is more noticeable. Can hear some details that did not hear before while more complex music.
• JAN 5654W Can Perfect Upgrade For Little Dot / Little Bear Amplifier, Directly replace 7-Pin 6J1 / 6Ж1 / 6J1P / 6J1P-EB / 6Zh1P-EV / 6AK5 / 6AK5W and EF95 tubes. It can also replace 6J2/6J3/6J4/6J5 and ordinary 5654. It can used for WE-403A/403B/EF95 Matched Vacuum Tubes replacement.
• Platinum Grade Pair JAN 5654W tubes show you the difference in natural voice reproduction and simple musical. Match it plate current and mutual conductance. Also pass a specialized life test, aging test and audio sound test.5654W tubes are NOS, It's new stock tubes.

In searching though one of my parts drawers, I found some small rubber feet I had saved "just in case" and two of the knobs shown (above) which are splined inside like the On/Off Volume switch is outside. The knobs I had found in the past for these were from Parts Express, and use set screws to secure them.

I tested the new unit on the stereo here beside me and it sounded fine. Next, I got started on the task of pulling the heavy stereo in the listening room away from it's location so that I could get to the back of it.

A 10mm wide-angle-lens shot of the listening room. The system is on a large and heavy glass and steel stand made for a very large HDTV and for many components. I modified it to have casters at each corner.

Since the PAT-6 only has one Tape input, I added a SONY audio/video switch for the TDK CD Recorder unit's output I have in the system. I used the QUAKEHOLD to secure it to the top of the PAT-6.

Here is an overhead view. Note the white power cord snaking away. I only had to unplug the RCA cables from the OUTPUT terminals of the PAT-6 and plug them into the (right pair) RCA outputs of the buffer. I added a good pair of RCA cables to bring the PAT'6's output to the input of the buffer.

Upon turning on the buffer, there was a low-level (and deep) hum. It seemed to me lower than 60 Hertz. "Hmm," I thought, "it didn't do that in the other room. But then, the speakers there only have eight inch woofers. These are twelve inches."

I was referring to the black Cerwin-Vega! LS-12 speakers. Which are the last models made in the United States. The smaller ones are vintage Dynaco A-25XL which have ten inch woofers. I switched to those and the hum was barely audible. Which is why I think it is not AC interference I am hearing.

Playing music, the hum is not audible and it only starts to get louder if the buffer's volume is past 50%. Nonetheless, I set out to eliminate the noise. 

"Okay," I thought, "I'll run a ground wire from the transformer."

Prior to that, I marked one terminal insulator and swapped the two AC terminals. It made no difference. 

The hum was still there! I decided to shield the white power cord. I cut some lengths of good quality aluminum tape and carefully wrapped the cord from the bundle all the way to the right-angle plug in three layers. I then fished the wires through  heat shrink tubing and shrunk it with a propane torch.

The hum seems quieter to me, but that may be wishful thinking. Again, as long as I keep the buffer's volume control below fifty percent, the hum is barely audible and not at all when the music is playing.

UPDATE: My friend in Arizona called and we talked about the issue. He concluded that maybe one of the capacitors is failing in the buffer's circuitry. My next step is to substitute that one back in this room to see if there is a hum, if not, then the one sitting on my PC into the listening room system to see if there is a hum...

In the interim, I have loaded these photos of post-cord-shielding.

I moved the unit away from the SONY switch (and wherever the preamp's transformer sits inside the cabinet) just in case that is causing the hum.

While on the subject, let me find a photo of the inside of the PAT-6 preamp-tuner...

As you can see, the transformer sits smack in the middle of the right side of the unit.

UPDATE TWO: I swapped into the listening room system the unit from the Yamaha stack (below, NOTE: I have since moved the OPPO to the top. I don't know what I was thinking.) and there WAS a hum from this unit, but not nearly as loud. Then, I swapped the transformers and there was no difference.

I first placed each unit on top of the dbx box, which of course, has a transformer inside it. No difference in the hum. Then, I gently placed each on top of the turntable and there was still a faint hum from the office's buffer and the same hum from the listening room unit.

Conclusion: Both the unit and it's transformer are hooked into the Yamaha stack. There is NO hum!* The speakers attached in here are two KLIPSCH KG-4s which have two eight inch woofers and a twelve inch passive radiator on the rear. And two of the latest BOSE 301 speakers which also have eight inch woofers. Therefore, neither will go deep enough to reproduce the hum, but will still receive it. *See third update below.

To conclude-conclude, I have purchased yet another buffer board from a different US seller. I will keep you posted.

Third UPDATE March 18, 2024: I received the replacement board (identical to all the other ones I have bought) from a different US seller of these completed boards via eBay. 

It is the one in front. Note, the rubber feet, while the one in the rear is secured with Quake Hold reusable adhesive.

I tried it initially in the Listening room system and the hum was still there! But, only audible on the largest speakers. ARRGH! Here, it is using the power supply with the unshielded cord.

Here, it is powered by the modified shielded cable. I tested them both, since in the Yamaha system it is placed in the Accessory RCA in and out terminals, using my Audio-Technica AIR ATH-AD700 headphones. They are THE best headphones I have ever tried and I have enjoyed them for many years.

They are super comfortable because they rest ON your head rather than clamped to your ears by tension. There are later models now for sale in the USA.

Here is a link to Audio- web page about them: ATH-AD700 | Audio-Technica should you like to get some. Specs on that page note frequency response of 5-30,000Hz.

Prior to bringing the new unit back into this room, I tried a test tone CD played through my  Cerwin-Vega! LS-12 speakers. They have the highest efficiency and lowest reach of the many speakers I own now. Their frequency response is 28-20,000 Hz and efficiency is 98dB, one watt at one meter.

The hum was there as soon as I turned the volume control up from zero. Through my Dynaco A25XL speakers it was barely audible.

I put a test tone CD in starting at 10Hz, nada then 20, zip 30 was audible, but too deep as was 40 and 50. 60Hz, as you are now thinking was identical!

Anyway, regardless of which system these units are installed in, at least in my home, there is an interfering 60 Hertz hum, whether the speakers can reproduce it or not.

I looked on eBay for better (i.e., more expensive) tube buffers but the lowest prices were near $200. On to Amazon I went, I chose two of these: 

【Upgrade】AIYIMA T2 6K4 Tube Preamplifier Bluetooth 5.0 with Treble & Bass Control HiFi Audio Preamp for Home Audio Amplifier System with DC12V Power Adapter

They were offering me a 10% discount. They use 12 volt DC power supplies and have full metal cases which I hope should prevent this hum. They should be here tomorrow, so I'm keeping my fingers crossed that they will work, sound good and be interference free.

Thank you for taking the time to read this article and commenting if you have ideas what might be causing the hum.

Scott Robb

March 18, 2024 Updated

#476

Review of Chinese-Market Cadillac ATS-L Luxury Sedan Kamo Brand 18th Scale Diecast Car Model

 January 21, 2024

#475

Gentle reader,

Back in April of 2023, we were looking for a newer car for me to use for when I travel from Northern Virginia all the way down to almost the border of North Carolina, as part of a KAIROS prison ministry team at Sussex I maximum security prison.

I wanted a manual transmission which greatly narrowed the field. I drive a 19-year-old turbo-Volvo wagon with a 6-speed and since it's rare, I do not want to subject it to potentially being hit by other vehicles. What with distracted driving and other things people keep doing. I've seen too many photos of wrecked ATS and Volvos in the various Facebook groups. We did test drive a nice late-model Mazda 6 but, I didn't like the used car dealer, something seemed hinky.

Our daughter texted us that she'd found a "Cadillac with a 6-speed manual in Colonial Beach!" And, thus, we were able to buy our very first Cadillac. We absolutely love the car, and like my 2005 Volvo V50, it is also rare having a manual transmission.

And here it is. Below is the box it came in. It was well protected. It came with a little plastic tool of some kind. I finally figured it out as being a door opener! Slip the hook in the door handle and gently pull. Finish opening the doors by hand. 

My AutoArt JDM 2002 Subaru WRS STi wagon also came with a similar, but more robust, tool, and now, I know what it is for. We owned a USDM 2002 Subaru WRX wagon. Here is that model, all opened up.

I reversed the image to make it look like it has left-hand-drive.

I am showing you an image (shot from a higher angle, because I'm tall) to let you compare the doors length. Here is a link to an article about the ATS-L: Cadillac Reveals Long-Wheelbase ATS-L For Chinese Market

"In China, prestigious vehicles are often used as chauffeured limousines, prioritizing rear seat space and extra rear features over the cars' counterparts in the U.S. and Europe. With its new ATS-L, Cadillac has stretched the regular ATS sedan's wheelbase by 85 millimeters to a new total of 2,860 mm. Interestingly, World Car Fans reports that the width of the car has gone up by 19 mm to 1,824 mm, and the height dropped by 6 mm to 1,421 mm."

85mm is just over 3 3/8th inches, therefore, we are not going to be able to tell the difference in length, in real life or (if there existed a non-L model) in miniature. Interesting that they somehow widened the L as well.

If you are viewing this article on something other than a handheld device, clicking or tapping any image will open a window over the article with ALL of the images much larger, so that you can look at details better.

The chrome details and other little things are very good on this model. 

As is to be expected, the front wheels/steering wheel turns/rotates. They strapped the car down so hard that bits of Styrofoam stuck to the tires. Cleaning it off was a bit of a job. A little is still visible on some of the tires.

There are little Cadillac Brembo brake calipers behind the front wheels. Another cool thing this car has: Sprung suspension. In the front, it is independent, in the rear the axle is solid, so they both move down and up in sync. More in the undercarriage photos.

You will get a closer look at the trunk's emblems in a photo further down. 

These three images are from the linked article above. 

They must have used a very w-i-d-e angle lens to take this image. It almost looks like the rear doors are rear-hinged!

I suppose for the average Chinese person, having an extra 85mm of rear seat legroom would be a lot. Anyone who owns an ATS knows, the back seat legroom in non-L form ATS leaves much to be desired.

Perhaps, if you are reading the linked article on a handheld device, one can spread the photo above. 

Using the included door opening tool, I was able to get everything open easily.

That's it for trunk opening. Which is not unusual in the diecast model world. Trunk is all lined with soft material, like the real cars.

They even replicated the heatshield above the turbocharger on the under hood insulation!

Almost looks ready to be climbed into and take for a spin.

Even the foot pedals are detailed. The shift paddles are a little thick, but that is understandable.

Note the engine size error above: 28T. The article linked lists the two engine sizes to be identical to standard ATS: 2.0T and 3.6 V6 N/A.

CUE screen is standing by to begin melting in the sun! My OCD wants me to reposition that rearview mirror. 

They even replicated the little forward-looking camera and the Head-Up display location. Sunroof does hinge upward, but that is it. That would be quite a trick to get it to slide into the roof!

Oh, and the side mirrors fold, just like the real car's do. If you look closely at these two photos, you can see flaws in the paint on this particular model. Had it cost three-figures, that would be unacceptable. 

But, I was $74.99 via eBay and this seller: jency739 | eBay Stores They, as of this writing, have twenty different Cadillac models from 1/64th through 1:18th scale. Most diecast, a few in resin.

And now, for the engine bay.

I was getting a reflection from the light on the windshield in this image. Below is better.

Pretty realistic, right? LOL! One can see they left off things like the strut braces and drive belts/pulleys. But, that's OK.

Sometimes, I handhold an LED flashlight to get more light under the hood, or into the interior of a car model I am shooting. 

In the latter, there was plenty of light to see interior details due to the model having four doors. In the case of these images, I lightened them digitally in Photoshop.

I parked the model right at the edge of the platform for these shots.

And now, the undercarriage!

When I took mine into my favorite (Volvo)* shop for the emissions test, he put it up on the rack so we could look around. Had I known he was going to do that, I would of taken pictures. Since I'm 67 and new to smart phones, I tend to forget that I always have a camera on me. 

*The Cadillac dealer near to us are quite a distance away. Where we had the car checked out by them and repaired after buying it, they don't have emission testing requirements, and thus, could not do the test. Only cities and larger population areas in Virginia are required to have emissions testing done bi-annually.

Rear axles are much thicker than in real life. For strength in the case of the model since it has springs.

All-in-all, I am pleased with this model. I had to chose which car model to remove from the cabinet. I chose the blue Viper GTS's spot, on the second-to-the-bottom diecast cars shelf.

In 1:18th scale, I have six models which represent (the closest I found, made to match the) real cars I have owned. They are, on the forth shelf from the top: A 1967 Chevrolet Impala SS. My third car, which I bought in 1975. It was a beige convertible with 327 V8 engine/automatic. The black model is hardtop with 427 big block V8/4-speed. To it's right is a Triumph Spitfire. Mine was the 1500 in red, and a year newer than the BRG model here. In front of that, is an Audi 100 Coupe, never sold in the US. Ours was a 100SL four-door sedan in silver/blue. My first European cars, both bought around 1979. NEXT shelf down: The previously shown Subaru WRX wagon, ours was the same color. Then, we bought a black 1987 Porsche 924S. The red model is the last year-made 924 (VW/Audi engine). And finally, the 2000 Audi TT quattro. Ours was that color, Denim Blue, inside and out. The model predates the addition of rear spoiler and other aero aids to prevent loss of control at Autobahn speeds which was happening to TTs. Lastly, on the bottom shelf, we grew up riding in VW Buses. At least three different ones that I can recall. In front of that: Driving home from high school in Spring of 1974, I spied a 1964 Pontiac GTO convertible with a FOR SALE sign in the window. I was driving my first car, a 1964 Chevy Impala two-door hardtop. I stopped, knocked on the door, the owner answered, got the keys and I test drove it. 389 three-two-barrel carburetors, four-speed manual, positraction rear end. The only thing wrong was a dent in the drivers door which could have been popped out from the inside. "How much do you want for it?" I asked. "Two-fifty, do you think that's too much?" For the first time in my life, I tried to have a poker face. "No, I paid $300 for this last year, and it's the same age." Since I was earning $1.65 an hour part time at a Mobil station, I did not have that much. My dad's answer when I asked to borrow $250 was, "But you already have a car." "But, Dad, it's a GTO!" "You could get in trouble with a car like that." He was correct. A few months later, I bought a 1964 Chevelle Malibu SS with a 327 V8, four barrel carburetor, four-speed manual and a positraction rear end for $250. Same car basically, smaller engine. Last model is a 2004 (made in Australia) Pontiac GTO. Of which, I would love to have a real one.

Since I'm going on about cars I once enjoyed owning, I might as well continue with the 1:24th scale models. Starting with the bottom row of big cars: A 1964 Chevrolet Impala SS on the left. It has the top 409 V8 engine and four-speed manual. Mine was tan with 283 small block V8 with a two-barrel carburetor and two-speed automatic transmission. In the middle is a dealer promotional model of a 1964 Chevelle Malibu SS. As mentioned, mine was a convertible, the same color. To the right is a Datsun 510. My dad needed a car to commute on the weekends to and from Washington, D.C. and Richmond, VA. We had a 510 on the lot, it that color, with a four-speed manual. He bought it. When he was home on the weekends, I was always borrowing that fun little car!

Next row up: I traded my Ford Escort wagon, which had a five-speed manual, for a black Chrysler Sebring convertible. It was black with grey interior. Nancy drove it. 

To the right of the Sebring is what this 1941 Plymouth Coupe I was making into a Hot Rod might have looked like, had I finished it. Oh, I miss that lean body. I was six feet three and 155 pounds, with muscle definition, I was SO skinny! I'm 176# now and have lost an inch of height, and a headful of hair.

I fell in love with Linda Frank, then my parents were moving to Northern Virginia. Her dad graciously offered to tow the car, take down his fence and put the car in their back yard! Linda and I broke up, but her parents loved me and told me the car could stay as long as I needed it to. I eventually sold it to a coworker.

OK, back to the story. To the right of the blue Plymouth is another dealer promotional model of a 1974 Chevy Vega. I had a Kammback, their name for the two-door Vega (and later, Monza) wagon. It was a fine car, (I was a Chevy dealer mechanic at the time and kept it running) it had a four-speed manual and no real options to speak of. 

Next shelf up: Another dealer promo of a 1975 Chevy Monza V8. I bought the real car from our next-door neighbor for $150. I intended to swap the V8 engine into the Vega wagon, but that never happened. I rattle-can spray painted it flat black and made Lexan covers for the headlights. A coworker asked me about the paint's color. "It's RAP." "Rap?" "Radar Absorbent Paint. I got it from a buddy at Andrews." (Air Force Base) "Really? Does it work?" "I haven't gotten a ticket yet." I waited a beat then I told him that I was messing with him. I never owned a Police car, but that is as close as I could find for TV's Adam-12's police car. The Porsche 924 Turbo is a plastic model I built. 

Next shelf up: We traded the Porsche 924S in on a 1996 Chevy Camaro Z28. V8, six-speed manual with T-Tops, of course. I built a 1:20th scale model to match it. The red promo model in a 1995. I sold the Z28 and the WRX wagon to buy the Audi TT. I do not have a Volvo C30 (red car next to the red TT). But, if you look at the row of Volvo wagons, second shelf from the bottom, you will see a grey V50 which is the same chassis as the C30, S40 and C70.

V50 T5 / M66 & ATS Performance 2.0T 6MT.

Whew! I never intended to rattle on like that about diecast cars representing real cars. I HAVE, however, written articles on many of the models comparing them to real cars we have owned.

Thank you for taking the time to read this rather long article. Feel free to comment below or on Facebook.

Scott Robb

January 21, 2024

#475