Audioromy 813 Amplifier
The quest for the el-cheapo high end continues.
Are we talking about an end of the Music Angel 845 supremacy here ?!
September 2010, by Lukasz Fikus
When it comes to amps, things are not as easy as with digital. With
digital we can make a 10 dollar piece of PCB sing well, just because of
some clever thinking and tricks. With amps - there is no substitute for
power, and power with good quality is expensive. A good amp is big,
heavy etc. That's why usually amps quality is directly proportional to
the price.
Usually but not always.
Audioromy is the best example that a lot can be achieved with minimal
funds, in fact - with pocket change.
On my last trip to Manhattan, I saw a poster: "super parking deal -
22,5 $ for first 30 minutes." I forgot to ask, how much is the SECOND
30 minutes. Anyhow - a dollar per minute is kind of bargain they offer
on big posters. Interesting.
That must be the best example of law of demand and supply - things are
worth what people are willing to pay for it, especially where demand is
high and resources (parking space) are scarce.
In Audio - people will pay the perceived value, not the real value, and
the perception is a very individual thing. Most audiophiles would
probably say that for a muscle triode amplifier of high quality they
would have to pay between 2 and 4 thousand Euro.
Thanks to the power of internet than informs us about the new products,
and thanks to the Communist Party of China macro economic policy (of
Juan exchange) and thanks to the absolute poverty and misery of China
factory workers, and due to Chinese general approach to
conservation of the Planet Earth (well, it was the West who exported to
china all pollution together with the jobs) - we can buy a very decent
amp like Audioromy 813 - for less than a decent interconnect. And
that includes a great amp, 7 tubes, packing carton, manual, tax,
and their profit.
Last time I checked - Audioromy sold for 660 US$ with free worldwide
shipping. That is 400 dollars net for the amp.
Also known as Suguang FU13 - here it is:
Cute amp, isn't it?
Tuning of Audioromy 813 / FU13 Class A tube amplifier
After getting it I thought that it looks okay, although not as cute as
on the ebay photos. The chrome mirror is kind of cheap one, amp is a
little bit too small, but generally - nothing major to complain.
The power tubes are gigantic. They seem bigger than 211's, than 845,
they are comparable to GM70, except that 813 have additional electrode
on top of their head.
The supplied 813's are obviously chinese made, but this radio
broadcasting tube was popular worldwide in the 50's and is available as
nos from many many brands.
The similar amp at similar price is called Sound Track 813 Class A
Integrated Valve Tube Amplifier and to me looks even better than
Audioromy.
Just look
It betters Audioromy on looks, and on selectable adjustable feedback.
It also has two monaural power transformers, audioromy has one commont
transformer.
The notes from first listening to a virgin Audioromy 813:
It is loud (not powerful but loud) meaning it is very sensitive and the
whole usable range of the pot is 1 hour. Bad input tube choice.
It has huge amount of one note thump thump bass, but we have no clue
about actual instrument playing it.
Generally the sound is okay, it is quite acceptable considering the
price.
But looking at these 813 power tubes I can see strong similarities to a
carbon 211, which reminds me about the Ongaku, and so the thought in my
poor brain goes like that: okay, save for the silver Kondo transformer
- this Audioromy is almost identical amp. Can we make it sound closer
to Ongaku than the present sound of a Yamaha home theater receiver ?
OK, this amp is listed as 50 Watts (for the Sound Track amp) and 30 W
for Audioromy , so even if I go down to 20 Watts, who cares, if the
sound will be good. I NEED ONLY 2 WATTS OF CLEAN POWER TO GO TO
NIRVANA with my 98 dB speakers.
Here is what the specs quote:
Specifications
Input Power
110V-240V AVAILABLE
Output Power
30W×2 RMS Class A
Output Tube
FU13 x 2
Frequency
20Hz-30KHz (±1dB)
Input/Driver Tube
12AU7 x2,6DJ8 x2
Rectifier tube
5Z3P x1
Ohms
8ohm or 4ohm
Lose true degree
0.5% (At Full Power)
Consumption
350W
Input Impedance
100K
Signal Inputs Level
200mV
Input Jack
2 groups
Size Dimension
Width 300mm x Height 370mm x Depth 250mm
Colour
Silver Body
Weight
28kg (2 x Parcel)
Packing Includes
All Tubes, 1.5m Power Cord & Hex Key
The internal inspection shows a good amp - no PCB on small tube area
(only PCB of power supply) , all point to point, neat job, good parts,
no safety horrors like in MUSIC angel.
internally I like this amp better than Music Angel but less than
Mingda.
The circuit was easy to reverse engineer: there is a high
amplification input tube - 6H1P in triode mode followed by ANOTHER 6H1P
in triode - giving ENORMOUS amplification. That's why the amp is so
bloody loud.
This is followed by a strange black octal pentode 6P6P, which drives
the power tube.
Power tube is a tetrode, but it is run in triode mode. This is good.
Power supply voltage is just under 800V DC which is perfect,
considering the modern cap rating rarely exceeding 400 V DC (they stack
two for 800V)
It has a global feedback loop (bad thing generally).
Lampizator's proposition of new Audioromy 813
My plan:
1. Cut and remove feedback loop.
2. Remove the voltage regulating stack of zeners from the input triode
supply
3. Increase the power supply cap near the pentode octal tube from
33 uF to 150 uF
4. Change the input tube to a much less sensitive and much more liquid
sounding Russian 6H6P (not i version and not 6H30P please)
5. Remove octal pentode and completely clean up the socket. Re-solder
heater wires to 7 and 8 pin.
6. Build a paralleled anode follower triode scheme in the octal base -
I suggest 6SN7GT or the one I actually used - russian equivalent 6H8C.
This tube quality is unimportant - no need for NOS redbases.
7. I adjusted the bias to I think 50 mA with two pots on the power
supply PCB.
Here is the old as well as new schematics.
If you want to finish it off nicely, please change the pot to 100K blue
alps, change the input signal wires to decent ones. Bypass all
electrolytes in small tube section with something like 220 nF / 400 V
MKP.
The mod is very easy and innocent. It is doable in 2 hours.
The sound was better than I expected. Not yet Ongaku, but very very
good.
Loudness decreased to "normally expected".
The bass was the best and most powerful I ever heard in my Nirvana
System. It beats my GM70 monos (theoretically 10 x more costly) and all
modified Liungs and Angels.
The stereo effect is excellent - wide, high, deep - full 3D / HD
The mids are ok, acceptable, but not drop dead gorgeous like I wished.
Probably it would take better internal wire and better coupling caps
than those I used.
The trebles are neutrally ok. Not bad at all.
Overall very impressive sound, I am very happy with it and I
recommend to everybody that cant afford a western made 845 kind of amp
like Cary 805, Verdier 845, audio Note Tomei, etc.
In direct comparison of fully Dietmarised Music Angel 845 the Audioromy
is better in every area except the midrange magic. Its midrange is a
little bit transistor like. It may however improve with some burn-in
period for all new tubes and caps.
Lukasz