Rectifier

0 Members and 1 Guest are viewing this topic. Read 2666 times.

Tomy2Tone

Rectifier
« on: 27 Aug 2016, 12:45 pm »
Anybody know if the 274b and 5R4 are viable replacements for the 5u4 in the Melody AN845?

FullRangeMan

  • Volunteer
  • Posts: 8825
  • All Tweeters look like a target, then shoot them!
    • Never go to a psychiatrist, adopt a straycat or dog. On the street they live only two years average.
Re: Rectifier
« Reply #1 on: 27 Aug 2016, 01:57 pm »
Anybody know if the 274b and 5R4 are viable replacements for the 5u4 in the Melody AN845?
A useful response must came from a Melody AN845 owner that have tested all these tubes, seems a rare event.
You have to compare the tube data sheet here:
http://www.mif.pg.gda.pl/homepages/frank/vs.html

If you Google you will find various specs from this amp:
http://www.cattylink.com/AN845.html
MELODY AODIXUN AN845 VACUUM TUBE INTEGRATED AMPLIFIER
GENERAL: 
AODIXUN is the premium line series developed by MELODY
Ultimate high end Class A vacuum tube amplifier from Melody
Anodised aluminum chassis with piano lacquered wooden side benches
Massive custom built transformers made from Japan imported materials
Net weight of AN845 over 42kg
Point to point hand wiring production
Ultra expensive high end parts: Mcap Supreme silver oil capacitors
Nichicon Gold, Solen Gold Label capacitors
Mundorf M-RESIST supreme resistors
Silver plated contact exchange mechanism for line input selection
Remote control for volume setting
5AR4 rectifying tube, NOS 6EM7 x 2 in preamplifier session
Gold plated CMC ceramic tube sockets, gold plated rca inputs
Nickel and gold plated WBT standard speaker out terminals
Terrific 845 authority with the silky mellow direct heated triode sound
RCA and XLR balanced inputs with shortest signal paths
Detachable power cord system (IEC)
TECHNICAL:
Rated Output Power: 22W x 2 RMS Class A
Frequency Response: 20Hz to 30Khz
Distortion THD: <1% (1Khz)
S/N Ratio: 88db
Input Impedance: 100Kohms
Input Sensitivity: 480mV
Output Load Impedance: 4 and 8 ohms
Tube Complement: 2 x 845,
                                     2 x 6EM7,

                                     1 x 5AR4 (5U4)
Remote Control: yes
Dimensions (mm, WHD) : 450 x 260 x 440

Hugh

Re: Rectifier
« Reply #2 on: 27 Aug 2016, 11:27 pm »
Tom,

I replied to your PMs.

The 274B is a good replacement.

Hugh


Tomy2Tone

Re: Rectifier
« Reply #3 on: 27 Aug 2016, 11:31 pm »
Tom,

I replied to your PMs.

The 274B is a good replacement.

Hugh

Thanks Hugh.

Is the 5r4 also possible?

Hugh

Re: Rectifier
« Reply #4 on: 28 Aug 2016, 12:20 am »
I'd stick with 274B.

Hugh

Re: Rectifier
« Reply #5 on: 29 Aug 2016, 10:52 pm »
Just FYI,

Do NOT waste your money on Psvane WE845.
We had 2 customers who tried those and they're not impressed given the money spent.

Also, stay away from KR845, Period.
They are NOT reliable.

FullRangeMan

  • Volunteer
  • Posts: 8825
  • All Tweeters look like a target, then shoot them!
    • Never go to a psychiatrist, adopt a straycat or dog. On the street they live only two years average.
Re: Rectifier
« Reply #6 on: 30 Aug 2016, 01:51 am »
Its a shame that big sino amps builders refuse to do GM70 and 6C33 amps :duh:
They insist in favor chinese tubes makers that are hi priced commercial products not military stuff.

Gopher

Re: Rectifier
« Reply #7 on: 30 Aug 2016, 01:57 am »
Just FYI,

Do NOT waste your money on Psvane WE845.
We had 2 customers who tried those and they're not impressed given the money spent.

I share this sentiment.  My fav current production are still the 845Bs. 

Hugh

Re: Rectifier
« Reply #8 on: 30 Aug 2016, 02:29 pm »
Its a shame that big sino amps builders refuse to do GM70 and 6C33 amps :duh:
They insist in favor chinese tubes makers that are hi priced commercial products not military stuff.

Not sure why that's the case.

Hugh

Re: Rectifier
« Reply #9 on: 30 Aug 2016, 02:30 pm »
I share this sentiment.  My fav current production are still the 845Bs.

Actually, the 845C is better but one would need to re-bias one's amp for this particular tube.

Hugh

Re: Rectifier
« Reply #10 on: 1 Sep 2016, 01:30 pm »
How does it sound Tom?

Tomy2Tone

Re: Rectifier
« Reply #11 on: 1 Sep 2016, 01:51 pm »
How does it sound Tom?

It's very nice. The previous owner had several amps and decided his Melody AN300b was the one he wanted to keep so this AN845 didn't get used much by him. When I first received it I noticed it would get distorted as the volume went up. Just happened to have a 5u4g recti on hand and replaced the NU it came with and the distortion went away so I'm wondering if the NU tube was on its way out or if it didn't seat right in the socket, I don't know. I have a few more rectifiers coming to roll. I currently have the Shuguang 845b's in and kept the stock Raytheon 6em7's in place.

But compared to my previous passive pre/ss amps the Melody has a much bigger soundstage and sounds a lot fuller. Acoustical blues sound amazing.

From what I read in the manual it did not suggest to turn the amp off at night but only when away from the house for long periods of time or if there's a thunder/lightning storm. Is this the normal recommendation or should you turn off the amp whenever its not in use?

Hugh

Re: Rectifier
« Reply #12 on: 1 Sep 2016, 02:05 pm »
It's very nice. The previous owner had several amps and decided his Melody AN300b was the one he wanted to keep so this AN845 didn't get used much by him. When I first received it I noticed it would get distorted as the volume went up. Just happened to have a 5u4g recti on hand and replaced the NU it came with and the distortion went away so I'm wondering if the NU tube was on its way out or if it didn't seat right in the socket, I don't know. I have a few more rectifiers coming to roll. I currently have the Shuguang 845b's in and kept the stock Raytheon 6em7's in place.

But compared to my previous passive pre/ss amps the Melody has a much bigger soundstage and sounds a lot fuller. Acoustical blues sound amazing.

From what I read in the manual it did not suggest to turn the amp off at night but only when away from the house for long periods of time or if there's a thunder/lightning storm. Is this the normal recommendation or should you turn off the amp whenever its not in use?

Morning Tom,

Prior to first turn it on, I'd make sure all tubes are not loose due to shipping.

I'd turn it off when not in use.

Enjoy.

Hugh

FullRangeMan

  • Volunteer
  • Posts: 8825
  • All Tweeters look like a target, then shoot them!
    • Never go to a psychiatrist, adopt a straycat or dog. On the street they live only two years average.
Re: Rectifier
« Reply #13 on: 2 Sep 2016, 11:45 am »
Morning Tom,

Prior to first turn it on, I'd make sure all tubes are not loose due to shipping.

I'd turn it off when not in use.

Enjoy.

Hugh
+1. Iam shocked an factory owner manual can say it.
Aside the wear of all parts will increase exponentially
(especially in summer) the electricity bill will:

Hugh

Re: Rectifier
« Reply #14 on: 2 Sep 2016, 02:46 pm »
+1. Iam shocked an factory owner manual can say it.
Aside the wear of all parts will increase exponentially
(especially in summer) the electricity bill will:


Actually not.

Ideally, it should be on all the time...albeit the obvious waste of electricity.
Contrary to what people think, wear and tear would increase with turning on and off.
Tubes are designed to last a very very long time.

FullRangeMan

  • Volunteer
  • Posts: 8825
  • All Tweeters look like a target, then shoot them!
    • Never go to a psychiatrist, adopt a straycat or dog. On the street they live only two years average.
Re: Rectifier
« Reply #15 on: 2 Sep 2016, 03:03 pm »
Actually not.

Ideally, it should be on all the time...albeit the obvious waste of electricity.
Contrary to what people think, wear and tear would increase with turning on and off.
Tubes are designed to last a very very long time.
All cathodes have a limited life, the cathode from Russian military monster GM70 last about 1500-1700 hours with soft start til sound start changing.

Grid and graphite plate are in good shape yet but tube are unsuited for audio due poor electrons emission.