Muzishare X7 Owners & Discussion Thread

[xlr8or]

1 hour ago, crazycatman said:

Well I received my X7 today. It's a very impressive looking beast indeed. However, it looks like I'm getting a red plate on V2. When biasing, the VU meter is off the chart for V1 and V2, then it  hardly moves for V3 and V4. I've tried moving the KT88s into different slots, and swapping round the 12AU7s but still no change. I've also swapped out the 5AR4 and the 12AX7 but no change either. I just get a red plate on V2 every time. I daren't leave this amp on for long incase it does some damage. Is this a faulty amp or am I missing something stupid? TIA

 

@SkunkieDesigns Any thoughts Stephe? Thanks!

[crazycatman]

4 minutes ago, xlr8or said:

 

@SkunkieDesigns Any thoughts Stephe? Thanks!

It's ok thanks, I fixed it. One negative wire was loose in a banana plug. All sorted now thankfully. That's a huge relief! Currently enjoying some Diana Krall and the X7 sounds superb. Now to let her break in ...

[xlr8or]

7 minutes ago, crazycatman said:

It's ok thanks, I fixed it. One negative wire was loose in a banana plug. All sorted now thankfully. That's a huge relief! Currently enjoying some Diana Krall and the X7 sounds superb. Now to let her break in ...

 

Just a tip for the future, a quad set of KT88 bias tube socket adapters would be handy in confirming the bias mA being set the same for each tube independent of the X7's VU meter. There are plenty of these bias adapters available on eBay.

[crazycatman]

8 minutes ago, xlr8or said:

 

Just a tip for the future, a quad set of KT88 bias tube socket adapters would be handy in confirming the bias mA being set the same for each tube independent of the X7's VU meter. There are plenty of these bias adapters available on eBay.

 

Great tip once again, thank you!

[SkunkieDesigns]

2 hours ago, xlr8or said:

 

@SkunkieDesigns Any thoughts Stephe? Thanks!

The amp I am working on had issues with the rotary switch used for setting the bias. It appears the contacts in these open switches are prone to corrosion. I would first just exercise them back and forth a dozen times and see if this cleans them up? Maybe spray them with some de-ox?

 

In this video I show how to replace them with higher quality units.
 

 

[SkunkieDesigns]

And this is my first impression on the amp sent to me for repair. Honestly this looks like a well designed and laid out amp, with possibly a few budget parts that need upgrading to make it a solid, reliable amp.
 

 

[crazycatman]

12 minutes ago, SkunkieDesigns said:

And this is my first impression on the amp sent to me for repair. Honestly this looks like a well designed and laid out amp, with possibly a few budget parts that need upgrading to make it a solid, reliable amp.
 

 

Thanks Skunkie, funny actually it was this exact video that I watched that made me choose the X7 over the Willsenton R8 that you also reviewed.  I'll have a watch of the first video you posted later once I've listened to this thing a bit more. I'm currently swapping between running my DAC directly through the X7 and using my Sansui 555a as a pre amp through the X7 pre ins. Kinda leaning towards the Sansui at present due to the tone controls. Either way the X7 sounds good even after only a couple of hours. Things can only get better!

 

(Speakers are Klipsch RP600M MK2 and DAC is a Schiit Modi 3E with a Wiim Mini streamer.)

[SkunkieDesigns]

24 minutes ago, crazycatman said:

Thanks Skunkie, funny actually it was this exact video that I watched that made me choose the X7 over the Willsenton R8 that you also reviewed.  I'll have a watch of the first video you posted later once I've listened to this thing a bit more. I'm currently swapping between running my DAC directly through the X7 and using my Sansui 555a as a pre amp through the X7 pre ins. Kinda leaning towards the Sansui at present due to the tone controls. Either way the X7 sounds good even after only a couple of hours. Things can only get better!

 

(Speakers are Klipsch RP600M MK2 and DAC is a Schiit Modi 3E with a Wiim Mini streamer.)

Let it burn in before you succumb to tone controls. A good tube amp shouldn't need them. 

[crazycatman]

11 minutes ago, SkunkieDesigns said:

Let it burn in before you succumb to tone controls. A good tube amp shouldn't need them. 

Will do. And great video of the switch repair thank you. That earned a sub

[crazycatman]

While we're on the subject of tone controls, I'm finding the amp sounds a bit thin and raspy when using the 8 ohm taps. Yes it's early days yet being 30 hours in to the break in period. However, a quick test of the 4 ohm taps seemed to fix it completely with a much fuller bottom end and far less raspiness. In fact I'd say it's near perfect and no need for tone controls!

 

I've read a few people do this. My speakers are Klipsch RP-600M MK2 and I believe their minimum impedance is around 3 ohms despite being a nominal 8 ohm speaker. Just want to check so see if anyone else uses the 4 ohm taps with 8 ohm speakers and will this break anything? Hopefully not as it has transformed the X7s sound for the better.

[muon*]

On 14/05/2023 at 5:15 PM, crazycatman said:

While we're on the subject of tone controls, I'm finding the amp sounds a bit thin and raspy when using the 8 ohm taps. Yes it's early days yet being 30 hours in to the break in period. However, a quick test of the 4 ohm taps seemed to fix it completely with a much fuller bottom end and far less raspiness. In fact I'd say it's near perfect and no need for tone controls!

 

I've read a few people do this. My speakers are Klipsch RP-600M MK2 and I believe their minimum impedance is around 3 ohms despite being a nominal 8 ohm speaker. Just want to check so see if anyone else uses the 4 ohm taps with 8 ohm speakers and will this break anything? Hopefully not as it has transformed the X7s sound for the better.

Your speaker are likely more suited to the 4ohm taps.

 

The nominal stated by speaker makers often don't tell the whole story.

Edited May 28, 2023 by muon*
typo

[SkunkieDesigns]

6 hours ago, crazycatman said:

While we're on the subject of tone controls, I'm finding the amp sounds a bit thin and raspy when using the 8 ohm taps. Yes it's early days yet being 30 hours in to the break in period. However, a quick test of the 4 ohm taps seemed to fix it completely with a much fuller bottom end and far less raspiness. In fact I'd say it's near perfect and no need for tone controls!

 

I've read a few people do this. My speakers are Klipsch RP-600M MK2 and I believe their minimum impedance is around 3 ohms despite being a nominal 8 ohm speaker. Just want to check so see if anyone else uses the 4 ohm taps with 8 ohm speakers and will this break anything? Hopefully not as it has transformed the X7s sound for the better.

 

It's not going to hurt anything. What IS bad is to run a signal through a tube amp with no speakers connected.

[SkunkieDesigns]

Here is the next video in the series where I am replacing the cheap factory bias pots with some nice Vishay ones.
 

 

[crazycatman]

Hello everyone, just thought I'd share my recent experiences with the X7 to get this thread going again.

 

Firstly, I swapped out the stock 12AU7s with a matched pair of RCA clear tops last week and they were pretty good with lots of detail, but a tad on the bright side. 

This week I swapped those out for a matched pair of JJ's ECC802S long plate tubes to go with my JJ's ECC803S 12AX7. They are brilliant and improved the bass with no harsh mid-range. Very listenable indeed, and relatively cheap and commonplace. Sorry I'm sure NOS sound better but they're outside of what I'm prepared to pay.

 

Finally today, I received my Topping E50 balanced DAC that can output to single ended and balanced at the same time, and swapped out my Schiit Modi 3E for it. I've got the balanced outputs going directly into the X7 and the single ended outputs going to the Sansui 555a as a pre amp. This lets me use the X7's pre-in switch to A/B between pure X7 and the Sansui pre amp. I'm pleased to say with the Topping the sound from both is much more livelier and crystal clear. The X7 on its own sounds a touch bright,  has slightly more pronounced mids (maybe the balanced effect?) but still a bit thin on bass, but I think I prefer the sweeter sound of the 555a's preamp. Much more easier on the ears. There really isn't much in it though and I don't lose any soundstage - both sound excellent. I just like the option of tone controls when they are needed, but most of the time they aren't necessary, unless a track comes on that I feel the need to flick the Sansui's magic loudness switch and all is well!

 

I do have 12 inch sub occasionally in the mix but that's because my Klipsch 600M's are small speakers. Lintons next maybe? 

 

Anyhow, I highly recommend the inexpensive JJ's ECC802S and the Topping E50 DAC on the X7. This was a fun and worthwhile learning experience and i hope it helps others . I'm grabbing some JJ's KT88s later today to try to fatten up that bottom end before I start looking at bigger speakers.

 

Edit: The JJs were a good improvement!

Edited May 27, 2023 by crazycatman

[SkunkieDesigns]

Yeah, I recommend replacing the KT88 tubes these come with. I put some KT88-Z tubes into the one I am working on and it really gave it some needed bottom end. You might try a 7025 pre-amp tube in the 12AX7 spot, I thought the EH7025 I tried sounded nice. Good tip on the JJ 12AU7, their small tubes do sound nice. 

[crazycatman]

Thanks Skunkie, do you have any more vids on the X7 coming out soon?  Been looking forward to some more content

 

I've read the JJ's E83CC 12AX7 tube is also a good replacement so I've got one of those on order. I also found, after swapping in the JJ's KT88s, that the stock 12 AU7s go well with them. Still waiting on a 1953 long black plate RCA 12AX7 to arrive from the States too, so will report back when that arrives. Will give that EH 7025 you mentioned a go too. Thanks for the tip!

 

The seller of the JJ'S KT88s had some TAD KT88 STR tubes for sale, but they looked near identical to the stock KT88s except for some extra internals at the bottom. The plates and everything else was the same. I still think the stockies are rebranded Psvane KT88-C. Happy with these JJs though.

 

Unfortunately, I think I'm getting a ground loop from the DAC setup I mentioned in my last post. Had to disconnect the balanced cables to the X7 to stop it. All units are on the same power board so I don't know why that's happening. Any ideas? 

Edited May 28, 2023 by crazycatman

[happyman3388]

Hi all, i am using X7 for 2 years and recently tried to use an external preamp and connect to the pre-in of the X7, the sound is not what I expected and upon a close look of the X7 circuit, I found that the pre-in in fact will still go through the built in pre amp stage , so practically it's a pre amp connected to built in pre amp, this design seems strange to me 

[xlr8or]

36 minutes ago, happyman3388 said:

Hi all, i am using X7 for 2 years and recently tried to use an external preamp and connect to the pre-in of the X7, the sound is not what I expected and upon a close look of the X7 circuit, I found that the pre-in in fact will still go through the built in pre amp stage , so practically it's a pre amp connected to built in pre amp, this design seems strange to me 

 

I think you'll find it's quite normal, as the front end 9-pin tubes are still needed to drive the octal power tubes. You would only be by-passing the volume control when the preamp selection is engaged. This is quite a common occurrence also in other Chinese made amps such as the Willsenton R8 etc.

[SkunkieDesigns]

2 hours ago, xlr8or said:

 

I think you'll find it's quite normal, as the front end 9-pin tubes are still needed to drive the octal power tubes. You would only be by-passing the volume control when the preamp selection is engaged. This is quite a common occurrence also in other Chinese made amps such as the Willsenton R8 etc.

Correct and like most of these types of amps, the input sensitivity is INSANELY high. 0.2Vrms input signal will drive this amp to pull power/clipping.  I don't recommend using these "preamp" modes, as you are going to need to use the volume control to attenuate the signal out of your pre-amp.

Edited May 28, 2023 by SkunkieDesigns

[SkunkieDesigns]

9 hours ago, crazycatman said:

Thanks Skunkie, do you have any more vids on the X7 coming out soon?  Been looking forward to some more content

 

 

 

Just posted one yesterday on replacing the choke and the two large filter caps. These caps are only rated for 450V and the first cap runs at 452V. Both of these see 475-480V on start up so they really should be 500V rated at a min. The choke is rated for 180ma, which should be enough given this choke only feeds the KT88 tubes biased at 40ma each, but I replaced it with a 250ma rated one just to ensure some headroom there as well.

More to come soon!
 

 

[happyman3388]

6 hours ago, SkunkieDesigns said:

Correct and like most of these types of amps, the input sensitivity is INSANELY high. 0.2Vrms input signal will drive this amp to pull power/clipping.  I don't recommend using these "preamp" modes, as you are going to need to use the volume control to attenuate the signal out of your pre-amp.

Yes, this type of integrated amp shall just stay as integrated 

[crazycatman]

10 hours ago, SkunkieDesigns said:

Correct and like most of these types of amps, the input sensitivity is INSANELY high. 0.2Vrms input signal will drive this amp to pull power/clipping.  I don't recommend using these "preamp" modes, as you are going to need to use the volume control to attenuate the signal out of your pre-amp.

Love the latest video, thank you!

 

Is this sensitivity something that can be fixed by replacing parts?

 

I don't have any problems using my Sansui AU555a as a preamp. I've set it's  volume knob to the loudest I'm comfortable with (about 10 o'clock), then just use the digital volume in my streamer app so it can never clip.  

[crazycatman]

More tube rollings! ......

 

So the JJ's E83CC was a winner most definitely, probably better than the ECC803S with more bass. Was loving this one for a couple of days then the '53 RCA long black plate came. Just a used one but testing very well, was not much more costly than new production. This one is staying put for a while I'd say, and with the stock 12AU7s, it's the best fit yet.

 

Incidentally, I spoke with China HiFi and they do not recommend swapping the 12AU7s for E80CC tubes, which are often used as a replacement. Shame as I hear they are great sounding. Please don't shoot the messenger!

[SkunkieDesigns]

Latest video running this amp on the scope and my analyzer suite. It looks really good here!
 

 

[crazycatman]

There are some good EOFY sales on at the moment for speakers. Has anyone used the X7 on a pair of Wharfedale Lintons? I'd be interested to hear your opinions.

 

Edit: and the Klipsch 8000F II

Edited June 5, 2023 by crazycatman