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Old 16th April 2009, 03:56 PM   #1
6J7 is offline 6J7
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Default 2A3 or KT88 ?

Hello,

First, sorry for my bad english..

Could you please help me before I buy a new amp ?
I had a Melody H88II (KT88) amp, I loved it but unfortunately it's broken, not still under warranty anymore and very expensive to be repaired ( I don't have the required knowledge for doing this myself).

So I have to buy a new one.

A lot of hesitations between Melody I2A3 and I880:

I2A3:
Vacuum Tubes: 2A34, 6SN74, 101Dx1
Power Output: 18W+18W, Class AB1
Frequency Response: 20Hz - 30KHz
Zero-Feedback
Input Impedance: 250KΩ
Output Impedance: 4Ω, 8Ω
Input Sensitivity: 480mV
S/N: ≥90dB
T.H.D: 1%

I880:
Vacuum Tubes: KT884, 6SN74, 101Dx1
Power Output: 50W+50W, Class AB1
Frequency Response: 20Hz - 20KHz
Input Impedance: 250KΩ
Output Impedance: 4Ω, 8Ω
Input Sensitivity: 480mV
S/N: ≥90dB
T.H.D: 1%

I have Cabasse Iroise 500 speakers (93db).

I listen to heavy metal, classical, electro, jazz, etc.
I like deep bass when listening for example to Tangerine Dream, Klaus Schulze, etc.

Now, a few questions..

- I2A3: 18w, is it ok for 93db speakers ? I don't listen to music very loudly but sometimes.. I like
- 101D tubes... it seems to be expensive to change and difficult to find.. right or not ? is it a "long life" tube ?
- what are the main "common" sound differences between 2A3 & KT88 ?
- do you think I'll have a lack of bass with I2A3 ?
- if you listen to heavy metal, it's better to have KT88 (pentode instead of triode): is this statement true ? or not at all ?

When reading this review: http://www.6moons.com/audioreviews/melody3/i2a3_2.html
The Melody I2A3 seems to be a fantastic integrated amp.. and doesn't "sound" typically like a 2A3 amp, no lack of bass, etc.

What do you think about it ?

Thanks for your help.
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Old 16th April 2009, 04:22 PM   #2
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I think you should repair your KT88 amp. Start a thread about the repair and you will definitely get a lot of advice. These amps are generally very simple and easy to repair. Unless the iron has given up the ghost.

An important difference between the amps you mention is the lack of NFB on the 2A3 amp. Due to the low damping factor this may or may not work well with your speakers. It's just impossible to tell without trying. The 2A3 will obviously sound different and you may find you listen to more classical and jazz and less heavy metal. Which can only be good
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Old 16th April 2009, 04:41 PM   #3
Jeb-D. is offline Jeb-D.  United States
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Quote:
I think you should repair your KT88 amp.
x2

If you liked the sound, get it repaired. You should be able to find somebody that can do it for a reasonable price. If you don't have experience around high voltage, I wouldn't attempt to do it yourself. But if you do, we can help you trouble shoot.

Getting the 2A3 amp seems like a gamble for your circumstance and preferences.
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Old 16th April 2009, 08:37 PM   #4
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I agree with the previous two posts. Fix your KT 88 amp. The pp 2A3 amp will not be suitable for the Cabasse speakers because of the poor dampening factor. You listen to dynamic music which means you need to have good control of the woofers in the speakers to get good clean bass. The Zu speakers in the 6 moons review are more sensitive by at least 3 db and with much simpler cross over and a much higher impedence. All this means that the dampening factor needed to control the Zu speaker is much less than your Cabasse speakers which has a much lower impedence and much more complex cross over
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Old 17th April 2009, 06:58 PM   #5
6J7 is offline 6J7
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Thanks for your advices, I won't go for a I2A3 amp.

And yes, I would prefer to get my KT88 amp repaired instead of "stupidly" buy a new one.
I'll open a new thread..

The technician said that the power transformer is dead (when switching on the amp, there is a big "hum" noise), and there is some "high voltage stage" components to change.. but I don't have the details, so I don't know which transformer to buy because Melody doesn't reply anymore to my messages..
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Old 17th April 2009, 07:45 PM   #6
MikeR is offline MikeR  United States
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My advice is don't buy another Melody amplifier.

You already have one bad one and you already know they have poor customer support. Two strikes against them.
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Old 17th April 2009, 08:03 PM   #7
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Have your tech remove the cooked transformer and have him find a transformer shop to rewind the power transformer. The transformer shop should be able to unwind the bad transformer and build up a new one with exact same windings to get the needed voltages. I would recommend having them wind a little bit heavier duty transformer. because these Chinese amps tend to run a undersized power transformer to save few pennies. While that is being done your tech can replace the toasted power supply parts. Most likely the power supply parts failed and took the power transformer out. Have him look at the power supply closely to make sure that it is up to the task. No point in spending the money to fix the amp only to have go up in flames in a year or so. When you get it back monitor how hot the power transformer is getting after the amps been playing for a few hours. If you can't keep your hand on the power transformer for more than a few seconds then you will have problems in the future and I suggest moving it. This repair shouldn't be to costly. Much less than a new amp. There are well designed amps available from the far east you just have to know what to look for. Check out the Silk web site. Google Search for Silk audio transformers.
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Old 19th April 2009, 09:32 AM   #8
6J7 is offline 6J7
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No, the tech didn't remove the transformer and didn't contact a transformer shop because I told him I'll contact Melody to see if it's possible to have a new one shipped.

I contacted the shop yesterday for more details, they said the tech said that there is the power transformer to change, some capacitors and resistors and a bridge (diodes?) but I don't know what exactly and it's a little bit tricky to ask exactly what are the components to change because the quote is too expensive and I'll try to repair it with a friend.

Anyway, the tech said this amp (Melody H88II) is a piece of crap, bad solderings, tube sockets in a bad shape, etc.

Do you have an idea about Melody amps ? is it really bad made despite the well finished impression ? I love it and it sounds good

I'll see for a transformer and open a new thread when I'll pick-up back my amp at home.

Thanks
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Old 19th April 2009, 11:52 AM   #9
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Interesting. I have never seen a Melody amp but was under impression it's one of the best Chinese brands. Improving/upgrading sockets and parts can be an easy and fun exercise. Obviously if you can afford to spend the time.

I cannot imagine repairing, incuding a transformer rewind would cost much more than a hundred euro. And it is probably unnecessary to reverse engineer the transformer. The output voltages should be obvious from the types of tubes and the rated power.
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