Any opinions / reviews on Gemtune APPJ PA1502A
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Mortus

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hello 
 
I am searching any opinion about this: Gemtune APPJ PA1502A  tube amp ,probably it is based on Miniwatt N3  APPJ PA0901A speaker amp
and if so miniwatt has good review ,has anybody hear of it ? is it worth any attention ?
 

Description


Class-A single-ended triode  and 100% tube amplification.  Designed for resolution of fine musical details, expansive soundstage presentation, and lush tonal quality.
6P6P Replaceable Tube: 6V6
6N4 Replaceable Tubes: 12AX7, ECC83, ECC803
Specifications:
• Tube: 6N4+6P6PX2
• Input: RCA Jacks
• Input Impedance: 10K ohms
• Input Sensitivity: 800mV
• Output: 6.3mm Jacks
• Output Impedance: 8 to 600 (Japan Z11-EI48*24 Output Transformers)
• Output voltage: 18Vp-p
• Frequency Response: 30-30Khz (+-1db)
• Input AC Voltage: 100-250V AC
• Power Consumption: 27W
• AC: Standard IEC Jack with Fuse protection (2A Fuse)
• Weight: 2.5kg
• Dimensions: 160mm (w) x 134mm (d) x 125mm (h)
• 0.13W/600 ohms   0.26W/300 ohms   0.5W/100 ohms   1W/32ohms
 

 
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pr0ggy

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Bump, would also like to hear some reviews.
 
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yangian

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Yes. Wondering about this:
https://www.massdrop.com/buy/appj-1502a-tube-headphone-amplifier
 
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kazcou

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I bought this amp recently. The first think coming to your mind is : the amp is small and not heavy. But do not worry, it is working very well. You can turn to the max, the sound still remain very clean. And it have enough power for mostly all headphones on market.
 
The first think you have to do is change the preamp tube. It a really bad tube ! Any 12AX7 will do a better job.
 
The power tubes is ok. But you can swap them for cheap, I got a pair of nos mazda 6V6GT for 30€ and moderns tubes are also selling for the same price. With the Mazda, I got a little more detail and the music is a little more sweet also.
You can also change the inter-stage coupling capacitors, put a 0,47uf 400v insteat of 0,1uf 400v, that make the amp more alive, with more deeper bass.
 
The isound signature is neutral, so the general signature is more depending on you DAC.
 
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yangian

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  I bought this amp recently. The first think coming to your mind is : the amp is small and not heavy. But do not worry, it is working very well. You can turn to the max, the sound still remain very clean. And it have enough power for mostly all headphones on market.
 
The first think you have to do is change the preamp tube. It a really bad tube ! Any 12AX7 will do a better job.
 
The power tubes is ok. But you can swap them for cheap, I got a pair of nos mazda 6V6GT for 30€ and moderns tubes are also selling for the same price. With the Mazda, I got a little more detail and the music is a little more sweet also.
You can also change the inter-stage coupling capacitors, put a 0,47uf 400v insteat of 0,1uf 400v, that make the amp more alive, with more deeper bass.
 
The isound signature is neutral, so the general signature is more depending on you DAC.
How is this compared to your other amplifiers? Thanks!
 
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kazcou

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  How is this compared to your other amplifiers? Thanks!
For the price is not a bad amplifier, but you have plenty of chinese amplifiers for that price.
the bass is ok
the treble is missing the typical warmth of tube sound,
the high is not enough airy
the spacialisation is ok
not enough details
I think, I need a better preamp tube, currentlly I have only some NOS Balwind and they are not very good.
I was thinking to use some NOS E188CC, but too bad the preamp tube heather is on 12,6V.
 
Now I have to read thousand of pages for looking a good 12ax7.
 
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yangian

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  For the price is not a bad amplifier, but you have plenty of chinese amplifiers for that price.
the bass is ok
the treble is missing the typical warmth of tube sound,
the high is not enough airy
the spacialisation is ok
not enough details
I think, I need a better preamp tube, currentlly I have only some NOS Balwind and they are not very good.
I was thinking to use some NOS E188CC, but too bad the preamp tube heather is on 12,6V.
 
Now I have to read thousand of pages for looking a good 12ax7.

Understand. Thank you!
 
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yangian

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  For the price is not a bad amplifier, but you have plenty of chinese amplifiers for that price.
the bass is ok
the treble is missing the typical warmth of tube sound,
the high is not enough airy
the spacialisation is ok
not enough details
I think, I need a better preamp tube, currentlly I have only some NOS Balwind and they are not very good.
I was thinking to use some NOS E188CC, but too bad the preamp tube heather is on 12,6V.
 
Now I have to read thousand of pages for looking a good 12ax7.

Any new impression of this? Thanks!
 
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CZ4A

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This amp is on Massdrop right now. I'm seriously considering it as a second amp, especially for the price. I have plenty of 12A(whatever)7s and a few 6V6GTs to roll. I've read the stock tubes are underwhelming at best and the 6P6P tubes look bad, with the glue peeking above the base.
 
Quote:
 
I think, I need a better preamp tube, currentlly I have only some NOS Balwind and they are not very good.
I was thinking to use some NOS E188CC, but too bad the preamp tube heather is on 12,6V.
 
Now I have to read thousand of pages for looking a good 12ax7.
You can probably roll some ECC81s or ECC82s if you have some. Less gain, though.
 
Also, do you happen how many amperes the preamp tube heater puts out?
 
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kazcou

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I want to use some E188CC because I have somesiemens, valvo, telfunkun, tesla, amperex, sylvania in stock

I think i need to rebias the heather.


It will be hard since there is no trimpot, so you have to change add a resistor.

I am amazed of that my tubes are still alive
 
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CZ4A

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Ok, I understand better now about the tubes.

I am not sure what you mean by "rebias the heather." By "heather" do you mean "heater?" Which contacts were you measuring? From the first picture it looks like the no. 4 or 5 pin contact but I can't see on the second picture.

In any case, I've put down my ducats for a 1502a on Massdrop. Should be interesting to compare with my Sunrise III.
 
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Here are some impressions by E8ArmyDiver from different threads. He's comparing it with a Schiit Vali 2 amp and driving the HE-400i. 
 
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I decided to go for this same combo. Both 400i and appJ are on the way.
 
For fellow european's: the appJ's are sold on amazon.de for very reasonable prices at the moment and in stock (+ free shipping in the EU). I got mine for 175 euro's. 
 
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APPJ is here! It's been breaking in for about 7 hours.

the original pre-amp tube isn't that terrible IMO, but lacks in definition and has a bit muddy bass. It is holding back the potential of the amp.

I've been rolling some oldies. Some first impressions

Mazda ecc82: lean bass, narrow soundstage, warm mids

Dario/Philips miniwatt ecc82: well balanced sound, open and detailed, much bigger soundstage, very enjoyable.

The miniwatt is the clear winner for now. Makes for a good match with the HE-400i.
 
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APPJ is here! It's been breaking in for about 7 hours.

the original pre-amp tube isn't that terrible IMO, but lacks in definition and has a bit muddy bass. It is holding back the potential of the amp.

I've been rolling some oldies. Some first impressions

Mazda ecc82: lean bass, narrow soundstage, warm mids

Dario/Philips miniwatt ecc82: well balanced sound, open and detailed, much bigger soundstage, very enjoyable.

The miniwatt is the clear winner for now. Makes for a good match with the HE-400i.
Cool! Will try to find one.
 
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