[braaam]

Update about the plate voltage CZ4A:

The plate voltage is 210V, and both 6G6 & 6W6 are good to use.

Now that's interesting since it seems a bit above spec for those types?

 

[CZ4A]

Originally Posted by chellity /img/forum/go_quote.gif
 
I tried out the vali 2 like others, and found it a little lacking.  I eventually found this amp and was surprised I could even get a full tube amp that would work with my 400i in this price range.  I bought a miniwatt ecc83, but the seller broke it so he sent me two equivalent quality tubes for the price of one I got pretty lucky..ended up with a fisher/amperex ecc83 and a dyanco/telefunken that I haven't even tried yet.  the amperex sounds so amazing that I don't even feel the need to pop in the telefunken yet.   I do find some microphonics on a few extreme songs, but i'm guessing its mostly because amperex ecc83s can be prone to ringing at times?  (neon indian, im looking at you)  I also tried some rca power tubes, but I'm not sure if they had a positive effect on the bass.  I might be interested in trying some newer power tubes, later.  
 

 
 

 
I can't quite tell from the picture, are the plates smooth or ribbed? Either way, you're in for a treat if you like a dryer sound. I have four T-Funk smooth plate 12AX7 (three of them very used up) and have tried them in the 1502A with my Sylvania 6V6GTs. braaam is right about them being analytical - the level of detail is impressive. The T-F smooth plates do lean bright, though, so take that into account with your power tubes - before my Sylvania 6V6GTs burned it the combination was almost painfully bright. I might try rolling some different power tubes soon, but for now I'm going to leave the T-Fs for my other amp. I'm currently using a gray plate GE 5-Star 5751 that does a good job of balancing out the highs with the lows.

Update about the plate voltage @CZ4A:
Now that's interesting since it seems a bit above spec for those types?

The 6W6 has a max plate voltage of 300V, so that isn't a problem (I was more concerned about the max screen voltage, but after re-reading the datasheet it may not be a problem after all). The 1502A's plate voltage is above spec for the 6G6 (180V) but that maybe not enough to cause huge problems- plus it may automatically bias the power tubes too.
 
If the manufacturer says they're OK to use it may be worth the ol' college try. I'll let you know how my 6W6GTs fare. The labels on the bases are gone so I don't know who made them but I suspect CBS Hytron. The type label is still present on the top of the glass, just like their 6SN7s.

 

[CZ4A]

I've tried my CBS(?) 6W6GTs in the 1502A and they work. I didn't see or hear anything troubling. I only had them on in for about an hour, so I'm not ready to give an impression yet. The 6W6 might make for a cheap rolling option if they sound good. They're much cheaper than most other power tubes on eBay. My Google-fu tells me they have limited uses, mostly in TVs. Sometimes they find their way into 6V6 guitar amps but they are not ideal.
 
http://www.antiqueradios.com/forums/viewtopic.php?f=6&t=91062 (just watch out for the shade they throw at us audioph00ls).
 
We might be coursing some uncharted territory with rolling the power tubes. Most of the discussions I've found about replacing 6V6s, 6W6s, 6L6s, etc. seem to apply to guitar amps or restoring vintage electronics. The only other modern, mass-produced amps I've seen that uses these octal power tubes are all-in-one Chi-Fi designs like this one, and I've seen no rolling discussions about them:
 
http://www.china-hifi-audio.com/en/yaqin-tube-amp-audio-c-14/yaqin-ms-6v6-hi-fi-vacuum-tube-integrated-amplifier-new-p-154

 

[CZ4A]

I hate to triple-post, but I have some more info for all you tube rollers out there.
 
First, my quartet of NOS Amperex 8416s I won from eBay arrived today. I've plugged one in with my CBS 6W6s.
 

 
Not only am I happy to report that the 8416 works in this amp, it sounds great! I'm still new at describing sound and there aren't any other 8416 reviews out there to glean from (on the other hand, I have to bias my opinion with), so bear with me. This is easily one of the most detailed tubes I've rolled. Highs are crisp without being piercing, has a good grip on bass, good attack. The 8416 is pricey and rare, but if you have the means, I highly recommend giving one a try!
 
Second, I've been on the hunt for another type of power tube to roll besides my 6W6GTs and 6V6GTs. Something in a shape other than a plain-Jane GT bottle, maybe. I sent out an e-mail to Gemtune and this was their answer:

 Yes,it may can supply for 6W6 tube,but it can't handle kt66,el34 and 6550 tubes.Thanks.

I wasn't able to get an actual amperage number, but based on the 6W6's amp draw, it look like 1.2A per power tube is the upper limit of the transformers. Someone earlier said Gemtune told them 6Y6 would work- that draws 1.25A, so that maybe might work. Goes to show that it's important to read the datasheets before rolling.
 
Unless anyone here wants to put their PA1502A on the line with a KT66 (1.3A) or above. For science. You monster.

 

 

[1800yolk]

I hate to triple-post, but I have some more info for all you tube rollers out there.

First, my quartet of NOS Amperex 8416s I won from eBay arrived today. I've plugged one in with my CBS 6W6s.




Not only am I happy to report that the 8416 works in this amp, it sounds great! I'm still new at describing sound and there aren't any other 8416 reviews out there to glean from (on the other hand, I have to bias my opinion with), so bear with me. This is easily one of the most detailed tubes I've rolled. Highs are crisp without being piercing, has a good grip on bass, good attack. The 8416 is pricey and rare, but if you have the means, I highly recommend giving one a try!

Second, I've been on the hunt for another type of power tube to roll besides my 6W6GTs and 6V6GTs. Something in a shape other than a plain-Jane GT bottle, maybe. I sent out an e-mail to Gemtune and this was their answer:
I wasn't able to get an actual amperage number, but based on the 6W6's amp draw, it look like 1.2A per power tube is the upper limit of the transformers. Someone earlier said Gemtune told them 6Y6 would work- that draws 1.25A, so that maybe might work. Goes to show that it's important to read the datasheets before rolling.

Unless anyone here wants to put their PA1502A on the line with a KT66 (1.3A) or above. For science. You monster.  

are you sure it's 1.2 amps and not 0.012 amps? I'm still learning about tubes in general and could be wrong, but if the tube can only handle about 2 watts..? I will do more reading though

 

[CZ4A]

are you sure it's 1.2 amps and not 0.012 amps? I'm still learning about tubes in general and could be wrong, but if the tube can only handle about 2 watts..? I will do more reading though

When I talk about amps, I'm talking about how much current a particular tube's heater (filament) draws from the amplifier in either amperes (1.2A) or milliamperes (1200mA). If a tube's heater current rating is too high, it will damage the transformer or other power supply.

 

[JordiMB]

Is this little amplifier a better value than the Little Dot Mk II, or similar? Don't know if you have any experience with both, to compare. Thanks.

 

[Wantat Chin]

hi all, i am decided to purchase this mini tube amp as my first tube amp, and i saw there is a 6v6>el84 socket, does it make improvement to use el84 instead of 6v6?

 

[canthearyou]

FYI I just listed mine for sale with a few extra tubes. It is a great amp, but I recently purchased a HE-500 and need to move some stuff to get a more powerful amp.

 

[1800yolk]

FYI I just listed mine for sale with a few extra tubes. It is a great amp, but I recently purchased a HE-500 and need to move some stuff to get a more powerful amp.

 
3 ohms extra resistance over the 400i's, i hope i don't have this issue as well. People on this thread like this amp with the 400i's, but until i listen myself.. some of my vinyl rips are on the quiet end, so we'll see D:

 

[canthearyou]

3 ohms extra resistance over the 400i's, i hope i don't have this issue as well. People on this thread like this amp with the 400i's, but until i listen myself.. some of my vinyl rips are on the quiet end, so we'll see D:

But it has -6db sensitivity.

 

[1800yolk]

But it has -6db sensitivity.

oh good point. i am considerably less worried now ha

 

[canthearyou]

oh good point. i am considerably less worried now ha

It sounds amazing with the 400i IMO and gets plenty loud on low gain.

 

[CZ4A]

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.

 

[a44100Hz]

If someone wants a silver one of these with some tubes drop me a line. (It's good; just don't need it anymore.)