KAEI TAP-1 Portable Hybrid Balance Headphone Amp
Nov 25, 2022 at 1:26 PM Post #272 of 380
KAEI introduced a smaller 3.5SE only tube amp. TAP-2.

On a AE product description the tube used in the TAP-2 is listed as "Using two American jan6418 tubes for RAYTHEON".
Maybe the TAP-1 is using the same tube?

S58c1a3eaa3814c3aafe7aa35dfa23d86i.jpg

Since my TAP-1S is disassembled, to modify the case, I took a photo of the four tubes.
They're taped, labeling down, to the bubble-wrap (Description from the AliExpress webstore - Air bag shock absorption technology: exclusive electronic tube suspension air shock absorption technology, effectively reducing the microphone effect).
So, I can't read the numbers on them.
But, they do look like photos of the Raytheon JAN 6418 tubes that are in eBay listings.
It is interesting that a lot of the small, portable, headphone amps are using NOS (New Old Stock) tubes that were designed in the 1950s & '60s - and that haven't been produced for 30 or 40 years.
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[ Photo of the inside of my KAEI TAP-1S ]
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KAEI_TAP-1S_Vacuum-Tubes.jpg
 
Nov 26, 2022 at 3:16 PM Post #273 of 380
Since my TAP-1S is disassembled, to modify the case, I took a photo of the four tubes.
They're taped, labeling down, to the bubble-wrap (Description from the AliExpress webstore - Air bag shock absorption technology: exclusive electronic tube suspension air shock absorption technology, effectively reducing the microphone effect).
So, I can't read the numbers on them.
But, they do look like photos of the Raytheon JAN 6418 tubes that are in eBay listings.
It is interesting that a lot of the small, portable, headphone amps are using NOS (New Old Stock) tubes that were designed in the 1950s & '60s - and that haven't been produced for 30 or 40 years.
.
[ Photo of the inside of my KAEI TAP-1S ]
.
KAEI_TAP-1S_Vacuum-Tubes.jpg
Can’t help but to find this funny:

“exclusive electronic tube suspension air shock absorption technology” = …bubble wrap

What will they think of next :)
 
Dec 14, 2022 at 9:43 PM Post #275 of 380
Well ... I didn't end up being able to use the X-Y table, bolted to my Dremel Drill Press - since the Z-axis mechanism that holds the Dremel, isn't stable enough to hold it stationary against the lateral forces that machining aluminum would produce.
But, I was able to use the Dremel, and some Cut Off Discs, to cut out the openings in the top of my TAP-1S.
There were a few scuffs & scrapes around the openings, so I went over them with a black permanent marker.
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My modified TAP-1S -
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2022-12-14_Modified-TAP-1S-Amp.jpg
 
Dec 29, 2022 at 7:30 AM Post #276 of 380
Well ... I didn't end up being able to use the X-Y table, bolted to my Dremel Drill Press - since the Z-axis mechanism that holds the Dremel, isn't stable enough to hold it stationary against the lateral forces that machining aluminum would produce.
But, I was able to use the Dremel, and some Cut Off Discs, to cut out the openings in the top of my TAP-1S.
There were a few scuffs & scrapes around the openings, so I went over them with a black permanent marker.
.
My modified TAP-1S -
.
2022-12-14_Modified-TAP-1S-Amp.jpg
Nice! Are you planning to install Burson V6 Vivid op-amps?
 
Dec 29, 2022 at 8:59 AM Post #277 of 380
Nice! Are you planning to install Burson V6 Vivid op-amps?

I can - but first, I'm going to measure the (+) and (-) supply voltages, to see which op-amps can be used safely.
 
Dec 29, 2022 at 9:09 AM Post #278 of 380
Can’t help but to find this funny:

“exclusive electronic tube suspension air shock absorption technology” = …bubble wrap

What will they think of next :)
Actually the "exclusive electronic tube suspension air shock absorption technology" is more than just bubble wrap, though most people will focus solely on that.

Photo credit: @DBaldock9
11919928.jpg


Most people will ignore / overlook the leads from the tubes to the PCB. The normal tube leads are solid wires. They replaced those leads with very flexible wires which allows the tubes to "float" on a cushion of air (contained in bubble wrap) lessening mechanical shock and tube ringing. It's really a clever design / workaround.
 
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Dec 29, 2022 at 9:27 AM Post #279 of 380
I can - but first, I'm going to measure the (+) and (-) supply voltages, to see which op-amps can be used safely.
I made those measurements some time ago...

pin 4 to ground: -7.9vdc
pin 8 to ground: +7.9vdc
pin 4 to pin 8: +15.8vdc

Pretty low rail voltages.

Edit: I read back on the previous page where you mention cutting the holes... looks like maybe SS3602 op-amps are your goal(?).
 
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Dec 29, 2022 at 2:01 PM Post #280 of 380
I made those measurements some time ago...

pin 4 to ground: -7.9vdc
pin 8 to ground: +7.9vdc
pin 4 to pin 8: +15.8vdc

Pretty low rail voltages.

Edit: I read back on the previous page where you mention cutting the holes... looks like maybe SS3602 op-amps are your goal(?).

I did do a quick check with a set of the SS3602 - but they had noise / oscillation, and were getting hot to the touch. So I installed a set of OPA-1622, and they're working fine.
 
Dec 29, 2022 at 6:26 PM Post #281 of 380
I did do a quick check with a set of the SS3602 - but they had noise / oscillation, and were getting hot to the touch. So I installed a set of OPA-1622, and they're working fine.
Well, that's nice to know. I tried Burson V5i-D op-amps without any issues, sounded great. Of course, can't slide the boards back in due to height clearance which you already resolved. I also picked up a couple Analog Devices AD827SQ per a recommendation by our friend @WoodyLuvr, but they did not work at all. Those AD827SQ had a loud hiss. That's actually why I measured the op-amp supply rails because I could not figure out the cause of the loud hiss. Since we don't have a schematic, the only thing I could think of is that the op-amp circuit is optimized for MUSES02, though the AD827SQ should be compatible and has the same pinout.

I did try NE5532 and Burson 5i-D which both worked fine, but those AD827SQ did not. Having said that, the AD827SQ did work in my Little Bear B4-X which has a higher + / - supply rail then the Tap-1. It could also be that I got counterfeit AD827SQ op-amps since I got them on ebay. Reliable sources like mouser or digikey don't have them in stock and I'm not even sure if Analog Devices still manufactures the AD827SQ.
 
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Dec 29, 2022 at 9:58 PM Post #282 of 380
I've also used a set of OPA-627-AU, and they sound good.
 
Dec 30, 2022 at 6:43 AM Post #283 of 380
I made those measurements some time ago...

pin 4 to ground: -7.9vdc
pin 8 to ground: +7.9vdc
pin 4 to pin 8: +15.8vdc

Pretty low rail voltages.
I made those measurements without the linear psu, so not sure if the values will change with the linear psu connected.
Edit: Nice to see Woody dropped in here.
 
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Jan 2, 2023 at 2:33 PM Post #284 of 380
Actually the "exclusive electronic tube suspension air shock absorption technology" is more than just bubble wrap, though most people will focus solely on that.

Photo credit: @DBaldock9
11919928.jpg


Most people will ignore / overlook the leads from the tubes to the PCB. The normal tube leads are solid wires. They replaced those leads with very flexible wires which allows the tubes to "float" on a cushion of air (contained in bubble wrap) lessening mechanical shock and tube ringing. It's really a clever design / workaround.



:)
 
Jan 5, 2023 at 2:55 PM Post #285 of 380
Ordered one a couple weeks back from Linsoul, it was apparently a pre order, now it says sold out, I ordered a DACless one, i hope it will be fulfilled, I really don’t want to buy a C9, or a little bear…
 
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