[1800yolk]

  Question for the current and prospective PA1502A owners reading this thread: Would you prefer it if I made a separate tube rolling thread? That way I can gather all of the info in from Gemtune and from my own research into the first post instead of it being scattered around.

i like that you are posting your findings here, since it relates directly to the amp we are all interested in. You could always do both though! But my vote would be to put the focus here mostly. As our tube rolling adventures continue, this forum will grow and more people will pay attention to this little-known amp, and more will get it, tube roll.. and then talk about it here! it's like an investment if you think about it. appreciate the info you've provided so far, should be getting my amp soon and will be going over posts again to figure out what tubes i'll shoot for first.

 

[chellity]

  Question for the current and prospective PA1502A owners reading this thread: Would you prefer it if I made a separate tube rolling thread? That way I can gather all of the info in from Gemtune and from my own research into the first post instead of it being scattered around.

 
i'm down would make it easier to see all the tube related info.

 

[Preludio]

.

 

[Preludio]

Interesting, didn't know these types could be used as well.

I went all French today: RT 6189 with the Visseaux 6F6. The RT is a military 12au7 screened for low noise. Very transparant and resolving with tight bass. A bit rolled off in the highs and a bit of sweetness in the mids. A great tube that fits a lot of styles.

Edit: update on the RT 6189

Listened to Bach's Concerto in E Major for Violin, Radiohead, Daft Punk, Patricia Barber. The RT 6189 is doing a lot (read: everything) right. Dynamic and alive with Daft Punk, intimate and never harsh with Patricia Barber and always in control with Radioheads "15 step". With Bach you can pick up every note from the different instruments but it all sounds coherent at the same time.

It may be resolving too much for things like black metal but that's not really a fault of the tube itself and could be fixed by using warmer power tubes I'm sure

It is close to perfection for what I'm looking for.

Hi, how was the soundstage imaging performance? compared to amperex dario philips?...

 

[Preludio]

High guys!, any opinions about this tubes?
 
12at7 RCA grey plate, aprox 22 USD. They're in my country so no extra shipping cost...
 
http://articulo.mercadolibre.com.pe/MPE-418158370-tubo-valvula-rca-12at7-grey-plate-nos-new-old-stock-_JM

 

[yangian]

How about this compared with LDIII or DV336? And how about it for HD600?

 

[canthearyou]

This little amp keeps surprising me. It does pretty well with the HE-500.

 

[CZ4A]

   
i'm down would make it easier to see all the tube related info.

 

 
i like that you are posting your findings here, since it relates directly to the amp we are all interested in. You could always do both though! But my vote would be to put the focus here mostly. As our tube rolling adventures continue, this forum will grow and more people will pay attention to this little-known amp, and more will get it, tube roll.. and then talk about it here! it's like an investment if you think about it. appreciate the info you've provided so far, should be getting my amp soon and will be going over posts again to figure out what tubes i'll shoot for first.

 
I think what I'll do is compile all the technical information we have here and put it in a separate thread. That way we have a one-stop shop for rolling info instead of leaving it all scattered.
 
Of course, I've been busy rolling new stuff too...

 

[1800yolk]

anybody know what this stuff is?


i don't have headphones to even test this out with, definitely doesn't look right though.
 
EDIT: I'm a dum dum. ignore this post!

 

[InAndOut]

Got this little baby on the last MassDrop and am loving it! Looking at some new tubes on Amazon. I think I'm going to go with a JJ 12AU7 Long Plate. And to the poster above, my left tube was a little unseated when it first arrived. I think the black covers around the Power tubes are just for show. I do like how the stock tubes have a tint to them.

 

[1800yolk]

anybody know what wattage this pumps out at any given impedance? Thanks
 
EDIT:
according to a rando user in the massdrop discussion:
 
Afterman:
Seems to be pretty good with power. Thinking of getting it. I like how it looks.
1W @ 32ohms
500mw @ 100ohms
260mw @ 300ohms
130mw @ 600ohms

 
so my calculation of 2.5W matches up close enough i guess, 2-2.5W
 
EDIT 2:
those numbers are probably on high gain, dunno what low gain would look like.
 
EDIT 3:
I think ultimately those numbers don't matter, what matters is whether or not we can get the volume we want without distortion, and as soon as i get some cans hooked up to this amp i will report back. still waiting on my dac to ship too. it being a transformer coupled amp, i think it will pair well with any low impedance cans, as many people have stated before me.

 

[1800yolk]

also, this was an interesting read. It clearly isn't the same app, but it definitely has to be made by appj. it consumes more power and is meant to drive speakers, but a few points that were interesting to me were:
 
"It also gives better performance, with the same regulated outputs regardless of inputs, brownouts or poor house wiring, and it drives the heaters with DC, not AC, so there's much less room for any hum. I tested it from 100 ~ 135 VAC, and saw no difference in heater brightness, power consumption, distortion or power output. This little jewel is completely immune to power supply variance, which few if any audio power amplifiers are."
 
and
 
It's microphonic: when tested into dummy loads in the lab, the transformers make sound, and playing test tones through speakers you may hear the innards of the tubes rattling.
 
also, he includes instructions on how to turn that amp into a monoblock amp. might be useful if you know what you're doing
 
also, my guess is that because peak to peak voltage is 18V, that should mean total output is 2.5 Watts. What I'm unsure of is whether or not each channel attains that peak to peak, or if that is combined. shows how much i know about electronics.

 

[DarthTater]

I've been listening to mine for several days.  With a pair of Beyerdynamic DT880s (250 ohms, I think) on high gain, it sounded pretty pedestrian.  I don't mean that in a bad way, just that it didn't particularly move me.  On low gain, it seemed kind of "closed up" to me; that is, it felt a little compressed, without a lot of dynamic punch.
 
Today I replaced the tubes with new manufacture Gold Lion ECC82 and a matched paiar of Electro-Harmonix 6V6GTs.  That made a pretty huge difference in terms of dynamic range, openness and soundstage.  I don't mean to imply that it turned a relatively bargain basement amp into an audiophile triumph, but I think that it's fighting above its weight at this point.
 
I find that the amplifier complements my Grado SR-225e's as well.  The bottom end is a bit rolled off, as you might expect, but on small group jazz recordings, particularly live ones, man, this thing really sounds great.  A lot of detail is there.

I think that even with the extra expense of replacing the tubes, this was a good deal through Massdrop.
 
The amp that 1800yolk described in the previous post sounds like the 1501A.  I use one of those to drive an old set of Stax SR-40s.  I replaced the stock tubes with some Zenith 6AD10s on the cheap and I really like it.  Other than running hotter than the dickens, it's a fun little micro amp.

 

[Halazzi]

A few quick observations after a week of office use, my apologies for being somewhat new to this and not having the full vernacular.
 
I had already picked up a NOS RCA preamp tube and a pair of 6V6G 1940s Westinghouse power tubes before the amp arrived so this is based only on using the NOS tubes, not the supplied ones. The 6V6G tubes are a little taller than the towers on the amp, I thought it made for a nice visual pairing (sorry no picture rights yet).
 
Having tried it with a few headphones, for whatever reason it seems to play better with orthos on high gain (400i, Mad Dog 3.2) than my Nighthawk on either gain setting. I do not have any other dynamics so I am not sure if it is just better with orthos or something specific with the Nighthawk.
 
In terms of sound quality, running ODAC -> 1502A -> 400i or Mad Dog was shockingly close (given the price disparity) to my home setup of Herus -> Valhalla 2. Not quite there, but much closer than I would have expected.

 

[CZ4A]

So I said I would post some more tube rolling results here. First of all, I got two new pairs of power output tubes - a pair of matched, nearly-new Tung-Sol Reissue KT66s (seller said they only had about 2 hours of use on them) and a used pair of 50's Soviet 6P3S tubes. "Wait," you say, "didn't you post earlier that KT66s draw too much current?" Well, the T-S KT66 is essentially the guts of their 6L6GC stuffed into a KT88 bottle, which also means the heaters draw only 0.9A, well within the PA1502A's capabilities. All of the other KT66s I looked at, both new and vintage, draw 1.3A, so they can't be used in this amp. Unfortunately, I lost the pictures I took of them. I will post them up later.
 
The 6P3S tubes are the Soviet copy of the 6L6G. Most are the straight-glass type, but there are still a few Coke bottle types around. Like these:
 

 
The 6P3S-E is a military version with extended life and higher plate/screen voltages like a 6L6GA. Electrically, the extra headroom isn't necessary in the APPJ because it isn't going to push its power tubes like a guitar amp. I don't know if there is any sonic difference between the 6P3S and 6P3S-E though. I can say these open up the soundstage a lot. And they're cheap. They may not be as good as some NOS American and European tubes, but they definitely are an improvement over the stock 6P6Ps and certainly hold their own.
 
I've collected up a few 12SN7GTs from various sources. The 12SN7 is the same as the famous 6SN7 except for the heater voltage, and since there are fewer applications for the 12V tubes, they tend to be cheaper. A 12SN7 to 12AU7 adapter is needed, but I'm stoked to say the 12SN7GT works in the APPJ!
 

T00bheads will recognize the power tube as the famous Tung-Sol Round Plate Black Glass. It fits with the 6P3Ss, too!
 

 
There's not a lot of space between the 12SN7 and the 6P3Ss, but that's because I went for the ST bottles. Straight bottle tubes will leave more space. Maybe the extra heat will lessen the 12SN7's life, but frankly I'm not that worried since the amp is open everywhere except for the transformer covers. If this were a closed amp I'd be more concerned. Plus, the 12SN7 + 6P3S combo just sounds awesome.