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APPJ PA0901 A (Miniwatt N3)

Thanks and it's fine to ask questions as that's the way I learned what little bit I know.

A fixed bias is one that has no adjustment and fixed bias/non-adjustable bias is pretty much the norm for single ended triode ( SET ) amps while the bias is adjustable and required for push pull amps.

You should consider the Sweet Peach FU50 single ended amp on ebay. It is rated at 10 watts and may have enough power to drive your B&W's at low to moderate levels.

The little Chinese flea amps are very affordable and the sound can be shockingly good.
 
So my 88db B&W speakers would be a no-no for this amp ? I wouldnt want to place any strain=damage on it. My listening room is small around 12ft square-ish.
 
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I'm afraid the N3 may run out of gas with 88db speakers. Sure it will drive them but with little head room and more heat/stress. My APPJ plays fine with 93 db speakers ( @1 o'clock volume ) in a small to moderate sized room but far better with the 98 db Zu's.

The FU50 amp is referred to as a pint sized 300b but at 10 wpc it's perhaps a little more powerful. The Sweet Peach FU50 ( the FU50 version is the only one to consider with this amp ) is made by Xiangsheng which is a large well known electronics manufacturer. Not much information on the N3's origins.

The Xiangsheng website states the Peach can drive inefficient 87-89db speakers at normal levels.

I've read everything I can find on the Peach and will probably buy one as the extra power would allow me to try some Mark Audio drivers in open baffles which I can not do with my 3.5 watt SET amps.

http://www.xshn.com/en/display.asp?id=20
 
Poultrygeist said:
.

A fixed bias is one that has no adjustment and fixed bias/non-adjustable bias is pretty much the norm for single ended triode ( SET ) amps while the bias is adjustable and required for push pull amps.
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Correction: fixed bias could be adjustable despite the name. Often, cathode biased amp automatically adjust the bias...

Patrice
 
Poultrygeist said:
If my amp's bias was adjustable I sure as heck wouldn't call it fixed.
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I understand it is not logical but here it is:

http://www.aikenamps.com/WhatIsBiasing.htm

Excerpt: "There are two main types of biasing: fixed biasing and cathode biasing. Fixed biasing does not mean the bias is not adjustable, in fact, it usually means the opposite. Cathode biasing is usually fixed, and not adjustable, and fixed biasing is usually adjustable with a small trimmer potentiometer, or "trimpot". It is no wonder the subject is confusing to people!"

I have here a Scott LK-72 with fixed bias but there was no pot to adjust the bias. I've added one...
 
Ive just ordered my own little APPJ PA0901A yesterday. How is everyone else doing with theirs ? Still going strong ? I need to get a phono stage too, probably a Graham Slee. I can see me spoiling this little tubed box !
 
I guess it would make far too much sense to use the terms adjustable and non-adjustable bias.

But of course someone would probably provide a link that says non-adjustable is still adjustable. :scratch2:
 
sthomas048 said:
Ive just ordered my own little APPJ PA0901A yesterday. How is everyone else doing with theirs ? Still going strong ? I need to get a phono stage too, probably a Graham Slee. I can see me spoiling this little tubed box !
Click to expand...

For the price of a Graham Slee you could pick up a Jolida JD9 tube phono stage. The thread here on the JD9 has been going strong for years.
 
Poultrygeist said:
I guess it would make far too much sense to use the terms adjustable and non-adjustable bias.

But of course someone would probably provide a link that says non-adjustable is still adjustable. :scratch2:
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Yes, it makes no sense and I prefer your way of "adjustable" and "non-adjustable". :D

And, for the record, it wasn't meant to start a debate, just to clear up an unlogical (but still used) terminology...

So, finally, this amp is cathode biased? Correct?

Patrice

EDITED: found a not so clear schematic: cathode biased with 300 ohms resistors on each side.
 
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Poultrygeist said:
For the price of a Graham Slee you could pick up a Jolida JD9 tube phono stage. The thread here on the JD9 has been going strong for years.
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Not really ! The Graham Slee is cheaper than the amp !

In the UK its tough to get a good valve amp at an affordable price. Brands like Jolida simply arent sold over here. You have the 'bay which sells Jolida and similar sorts plus the usual Chinese imports, but for UK buyers its tough because 99.9% of those amps arent compabtile with the british 240v power supply.

My plan is to test the waters with this amp and in time move onwards and upwards to maybe an Icon Audio amp. This little amp is perfect for me right now.
 
Well my little APPJ arrived today and its pumping out tunes more than loud enough with my B&Ws at the 12 o'clock position. Lovely rich sound and very musical too. This amp really is a bargain.

<UPDATE>
Still having fun with this new amp. However Ive noticed some issues with sound. While vocals are brilliant and natural, the overall sound seems congested and lacks clarity and separation. Is this normal for a new tube amp of this sort ? Maybe it needs to break in ? I would appreciate any advice.
 
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I realize this is a difficult comparison, and that I am posting in the tube audio forum, but how would the APPJ (with upgraded tubes) compare against the best T-amps?
 
sthomas048 said:
Well my little APPJ arrived today and its pumping out tunes more than loud enough with my B&Ws at the 12 o'clock position. Lovely rich sound and very musical too. This amp really is a bargain.

<UPDATE>
Still having fun with this new amp. However Ive noticed some issues with sound. While vocals are brilliant and natural, the overall sound seems congested and lacks clarity and separation. Is this normal for a new tube amp of this sort ? Maybe it needs to break in ? I would appreciate any advice.
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Maybe a bit but I'd roll the cheap Chinese tubes starting with the 12AX7. In my original four tube MW S1 it made a huge improvement but remember that the MW's forte is driving high efficiency full range speakers.

Compared to the Topping T21, Dayton DTA100, and Lapai, I prefer the MW.
 
jkilla said:
I realize this is a difficult comparison, and that I am posting in the tube audio forum, but how would the APPJ (with upgraded tubes) compare against the best T-amps?
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Well I have owned a KingRex amp and currently own a APPJ. I would say most digital amps major on clarity and details, there is some tube-ness there but not a great deal. The APPJ will give you a richer/more musical sound and good timing. But there isnt acres of difference at this price level.
 
I just got my two PA0901A APPJs two weeks ago (very fast shipping.) I haven't had much chance to listen to them as I'm finishing up my DIY speakers (Dayton Audio RS150P-8 woofers and SB Acoustics SB29RDC C000-4 tweeters in Dayton .23 cu. ft. boxes, with a MiniDSP as the crossover.)

Does anybody think there'll be an issue using one channel of each amp in 4 ohm and the other channel in 8 ohm? I'm using one amp for each speaker, with one channel driving the 8ohm woofer and the other channel driving the 4ohm tweeter. I think I know the answer, but I'm kinda new at this.

I'm also using an old 2.2 cu. ft. Dalco subwoofer box with the Dayton DVC310-88, with another MiniDSP and two Kenwood L-O5M monoblocks, which probably need re-capping, at least.
 
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crossrh said:
I just got my two PA0901A APPJs two weeks ago (very fast shipping.) I haven't had much chance to listen to them as I'm finishing up my DIY speakers (Dayton Audio RS150P-8 woofers and SB Acoustics SB29RDC C000-4 tweeters in Dayton .23 cu. ft. boxes, with a MiniDSP as the crossover.)

Does anybody think there'll be an issue using one channel of each amp in 4 ohm and the other channel in 8 ohm? I'm using one amp for each speaker, with one channel driving the 8ohm woofer and the other channel driving the 4ohm tweeter. I think I know the answer, but I'm kinda new at this.

I'm also using an old 2.2 cu. ft. Dalco subwoofer box with the Dayton DVC310-88, with another MiniDSP and two Kenwood L-O5M monoblocks, which probably need re-capping, at least.
Click to expand...

I'm not clear on just what your planning to do. I'm sure someone will come along with an answer shortly. Anyway, welcome to AK.

cubdog
 
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