Music angel amps

[arvin]

I already have a yarland 34 amp and have been looking at the music angel amps with kt88 tubes, are they worth buying?

How good are they?

[jesabel]

Hi. I'm new to this forum. I have bought a Music Angel KT88 amp (2 of them in fact), from China (ebay). Myself and a friend decided to take the risk and buy one between us, and go halves if it was no good. In fact we both found it quite stunning! So we had to buy another one. I was running an Audiolab 8000C pre amp and 4 Rotel RB850 power amps, and felt they were lacking clarity. My friend was running an Audiolab 8000C and a pair of Audiolab 8000M monoblocks - a very good set of amps no doubt. Both of us could not believe the massive improvement in clarity and stereo separation. It was like listening to all favourite CDs for the first time - so much there that we had never heard before! Neither of us have used our other amps since. Unfortunately mine has developed a fault after only 2 weeks, and it is not worth sending it back to China as the shipping costs more than the amp, but they have sent me the schematics and I have taken it to a local repair man to get sorted. Dispite this, it's worth every penny. Looks great and sounds superb.

[arvin]

where did you obtain these amps please?

How much exactly were they?

[Original Burnedfingers]

If you had checked prior threads you would have found one from gingertube "My experience with Music Angel Amps EL34"

What would seem to be a good deal on the surface turns out to be more expensive than buying a good used tube amp that is made by a suitable manufacturer. The amps have numerous quality control issues. They don't seem to run over 6 months without developing a defect of some type. They use cheap transformers and are put together probably by a 10 year old working in a sweat shop.

Sorry but I will pass them up on the name alone. My suggestion is to put them on ebay while they are still operational and auction them off to get your money back. Once that is done shop for a decent tube amplifier that will still be operational 15 years from now.

[Original Burnedfingers]

but they have sent me the schematics and I have taken it to a local repair man

Why don't you post the schematic so we can have a look see?

[jesabel]

Arvin. The amps were bought from ebay seller jennychan4028. For both I paid for express delivery (DHL) from Hong Kong. Both were shipped on a Thursday and both arrived on my doorstep (UK) Friday lunchtime. They are on a buy-it-now for £230, but I bought both on auctions, paying £140 and £165 respectively. I believe you can get them in the UK from Alphamission (ebay again).

For anyone that's interested, I have no idea how old the person is (or was) that put them together. I speak from personal experience and from the comments made so far from the expert (of 50 years) who is repairing it - and that is that the quality is not bad at all. Most of the components within are made by recognisd brands. The general assembly and workmanship is okay (not brilliant, but not bad either). It weighs 26kg, a measure of the size of the transformers - a good thing I understand! I cannot speak of the quality of the transformers themselves - they are encased in metal covers, but I do know that overall the sound quality knocks the socks off Audiolab's best.
I have instructed the repair man to change any components that he thinks are below par, or that would improve reliability or sound quality. So far he is quite happy it. He has fixed the problem. It was a faulty diode in the RH power supply circuit. Not major.

You can also get valve amps in the UK (through ebay) again - Chinese made amps which are then modified/improved in the UK. No doubt these are better quality, but you pay £1400 for one. I paid £300 including shipping and duty. I don't therefore mind too much if I have to spend £100 repairing/improving it. There are also comments about Chinese imports being for 220v, and as such not suitable for UK voltage (at 240v). In fact they all have a least a +/- 5% tolerance, and the UK is currently on 230v. Again, no problem.
They drive my Kef 107's with superb clarity and depth. I'm sticking with it for now!

[jesabel]

Schematic of Music Angel XD800 KT88 amp as requested.

[aau70]

I bought one last year from eaudioguy (ebay).
Just be carefull, mine does not have grounding ( I need to ground it my self)
It has 2 mode triode and ultra linear and It's making a loud popping sound when you turn off the amp in triode mode
It is still working well, nothing special until: I read a posting re this amp in this forum:
Help! Upgrade a Music Angel KT88
You won't believe the improvement when you disable the ultra linear/triode switch.
The sound stage is amazing, just like different class amp.
If you bought this amp, I recommend you to:
1. Check the grounding.
2. disable the ultra linear/ triode switch (triode all the time)
but be carefull, it's high voltage inside

Cheers

[OXAUDIO]

I am in the process of repairing/modifying one of the Music Angel KT88 Amplifiers, and have found C25 to be faulty, along with the 1n4007 diodes, in one channel's preamp/phase splitter supply. As a result I have changed C25 & C27 in both channels for JJ 47uf 400v Capacitors, and may well change other PSU filter capacitors as a precaution, since I don't know what caused C25 to fail, but this meant that the HT(B+) was only about 265v instead of 400v, and caused a loud hum in one channel.
There was no mains earth connection to this one,either. This has now been rectified. With regard to the mains supply, what is the opinion of other UK contributors regarding the unfused mains lead/plug assembly supplied with these amplifier?

[OXAUDIO]

Further to my post yesterday, and, after having made some further checks on the amp. I am in pricess of repairing, i can report that various modifications have beem made, seemingly by the manufacturers, which address some of the points raised by EC8010 on 12-07-06, and by gingertube, amongst others. In particular the circuitry around the driver stages has been revised, including raising R23 & 25 to 660k, fitting 1k grid stoppers to the KT88s, and other modifications. I may redraw the schematic to show the changes, and post a copy on the forum, if I get time.

The grid stoppers have been fitted on the preamp PCB, which results in long(-ish) flexible leads to two of the KT88 tube bases.
I am in the process of rewiring the resistors directly to the tube bases, and have also fitted 0.22uf 275vac Class X capacitors in parallel to C7 in each channel. Due to the PCB layout there appears to be no room to fit similar capacitors accross C5, which might be desirable.

In the original Williamson design a series r/c network was fitted accros V1(a) anode(plate) load resistor R3, but I haven't checked whether this is present on this amp.

I have not yet added balancing resistors accross any of the PSU Filter Capacitors, nor changed the 1n4007s for UF4007s, nor powered up the amp. since making the changes noted above, consequently I do not yet know what, if any, effect these changes have had

Some versions of this amplifier do not have the LF chokes in the negative HT line. Instead a 33 Ohm resistor(R55) is fitted. Since an L/C filter(in my opinion) is better than an R/C filter I shall retain the chokes, but would be interested in other users opinions on this one.

Incidentally, jesabel, I have been in the repair trade 35 years, not 50 - I am not(quite!) that old!