tube amp Archives - Quartz Acoustic Pte Ltd

Muzishare X7 KT88 Class AB Push-pull Integrated Tube Amp in details

August 18, 2022August 18, 2022 2 Comments

Muzishare X7 KT88 Tube Amp has attracted vast attentions since QA has moved into a shopfront to allow the audition of this wonderful amplifier. Our bad for taking so long in getting the details of the amp into writing as there just too many stuffs to settle in setting up of the shop. So let go straight into a better detailed introduction of the X7 for more accurate information instead of hearsays and misnomers being fed to our customers and misinterpreting the facts.

Above: Video of the sound demo with Muzishare X7

As the official dealer for Muzishare in Singapore, tube amps sold from QA will always be the latest version of what Muzishare has to offer, make no mistake about that. We can understand that due to the lack of recognition and information of Muzishare in Singapore, some details being posted from unofficial routes or channels not from QA may not be the most updated ones. So in any case, please just seek us out for any clarifications.

Reason for saying this being that the current X7 QA is selling is the latest model since beginning of 2022. Yes, now is already 8 months into 2022, but we do have customers comparing cheaper X7s out there when they were the older models WITHOUT the balanced inputs and better optimization of the circuits within. By getting Muzishare products from QA, you are making your spending worthwhile with official support and warranty for the updated models.

To clear another doubt about whether the balance inputs in X7 are truly balanced – yes, they are. The higher end models, but still considerably affordable in comparison for now, of Muzishare tube amps are getting balanced inputs as a future-proofing design consideration. More DACs are getting balanced outputs nowadays, as the number of DACs exploded into scenes for consumers in the past few years. It should not really be a surprise to see tube amps getting such inputs for a more improvement in dynamics and noise reduction in connections when digital music is concerned. What is surprising is some other brands of tube amps are still not making balanced inputs available. Which is why such spec being available in Muzishare tube amps is what makes the price performance ratio exceptionally high.

Above: back panel of the X7 detailing the phono, balanced and pre inputs

The balanced inputs are followed by 2x line in inputs, 1x phono input and 1x pre in. Generally 2x line ins and 1x balanced in for this price range of the amps should be suffice for most users. The presence of the phono input is another bonus for some users who may have just starting into vinyl playing can consider playing with that. We always manage the expectation to our customers and with regards to the phono input, an external phono stage will always triumph any build-in phono pre amp most of the time. We should just treat this presence of a phono input as a bonus good-to-have feature, which can come in handy in anytime of troubleshooting future external phono stage – who knows? Such feature is not available in many other amps while still costing less, so why not?

Pre-ins are not getting uncommon in Muzishare tube amps too. By connecting to a pre-amp one may have, all volume control will be ceded to that, and Muzishare tube amps, the X7 in this case, will be acting as the power amp. Again, another misinformation floating around was that preamps tubes will not be used when pre amp is connected via pre-in – they do. Caveat of using pre-in will be the restriction to using single-ended RCA connection instead of any possibility of using balance connections. However, balanced pre-in is really a niche in tube amp. It will no doubt raise some cost of it on such implementation, but this is definitely a feature QA will hope to see in future Muzishare integrated tube amps as well.

Going to the front of the unit, from the left, we are greeted with something familiar for users who have seen it in the X5. And that is the toggle switch to change between triode and ultralinear modes. Basically triode mode has less power output, at 25W per channel while ultralinear mode produces the maximum power from the 4x KT88 tubes at 45W per channel. 45W per channel is aplenty of power in tube amps specs, rivalling and equivalent to 200-250W per channel of solid state (SS) amps. Hence there is really no issue of X7 not able to drive certain speakers. They are definitely able to drive most speakers out there as low of a sensitivity as 82-83dB no problem.

Above: a pair of toggle switches and a pair of VU meters

Ultralinear mode unleashes to the speakers in its maximum capability, providing the juice and power if ever the speakers need. High dynamics in the frequency spectrum, crisps highs, engaging mids and importantly, deep and tight bass. The wide stereo imaging X7 gives make music listening a truly enjoyable experience, and we are not even talking about the merits of tube-y sound yet.

The clean and precise sound signature of KT88s is the reason why QA always mentioned that they are the best tube type for any one entering or transitioning into tube amps from SS amps. They can almost sound like one, even by any reason if they do not (which is not a deficiency of tube sounds), the tube sounding characteristic will carry you over into another form of enjoyment – emotional enjoyment. Vocals will sound magically sweeter and more realistic, for which we are no longer hearing into the technical part of music listening (some of you will understand what this means), but just purely enjoying music. This literally should be what it is. Even for Classical/Ensemble fans, the lack of vocals will still be up to the treat in that the level of details KT88s can bring to pick up the various instruments is playing is just fascinating.

As for 25W per channel triode mode, the reason of its existence is the flexibility of sounds X7, like the X5, can give. This lower powered mode is useful for higher sensitivity speakers like horns and full range speakers, where the sound signature is also more midrange focused. Listening to Jazz or Oldies where the warmth of tube sound is so desired will appreciate the triode mode available for toggling. The more laid-back and mellow harmonics from triode mode can never make listening on the X7 a fatiguing experience, especially on lower volumes on some late-night music relaxation.

Above: single-ended headphones with 6.35mm plug can enjoy the powerful KT88 driving headphones while another pair of precisely-CNCed msooth knobs are on display showcasing top-notch quality.

KT88 tubes for headphone usage tend to be a bit overkill in all honesty but still can be done with the presence of a 6.35mm single-ended headphone jack. Admittedly not being marketed as a headphone amp, the TRS connection is still available for compatible headphones to be plugged in and be driven with great power in melodic sweet nature of the tubes.

X7 employs a dual VU meter for each channel and as the grooves play, the needle will dance beautifully in the warm, orange back-lit glow of the meter, giving one a sense of nostalgia in a modern-designed amplifier outfit. The VU meter is also crucial for biasing adjustment for the KT88 power tubes, which is made very easy in all Muzishare tube amps with just a simple switch of knobs and trim pots-turning with a small flat head screwdriver.

Turning the knob at the top of the amplifier near the tubes to the respective power tube V1 to V4 (two to each knob, one of each side), the needle will show that particular tube biasing current. The needle should be pointed to 40mA – that is the correct biasing current for KT88 and 6550 tubes in X7. New X7 owners should have no need to adjust anything as it was already done accurately right out from the factory in most cases. There is no harm to switch the knobs to check for it, even when music is playing. However, do take note any future bias adjustment should be done at least 30 minutes in after the amp is switched on, just so the electricity and heat has stabilised the tube for a more accurate reading without much drifting.

Above: turning the biasing knob to the respective tube allows adjustment of its bias through reading of the VU meter

Contrary to some myths, please understand only power tubes need biasing. Preamp tubes do not need biasing. Both tube types, however, will need matching in order for the specs of the tubes in their pairs or quads to be as close and similar to one another in order for the two channels to run exactly the same as much as possible. Still, each and every tube is different. A perfectly identical spec matched tubes may over time drifted and aged at different speeds. That is perfectly normal. Hence it is a good practice to check on the bias reading every few months because the tubes may be drifted higher or lower from the ideal range. Again, that is normal. Just adjust them back.

A single rectifier tube is present in X7, which makes this tube a very likely first to be rolled, in QA’s opinion. As with all mentions to our customers, QA firmly believes the merit of a rectifier tube in tube amps and Muzishare so far is upholding that ethos too. As much as the rectifier being a simple function of converting AC to DC which can be easily done by a small transistor chip, having a rectifier tube doing this job in a tube amp speaks volume in Muzishare tube amps as a true tube amp in this regard. Some, if not most, brands have chosen not to use rectifier tube(s) and that is totally fine. For our case, rolling the rectifier tube(s) in Muzishare tube amps give users an additional avenue of play, of fun, and chance to further improve the sound – yes, rolling rectifier tube(s) affect the sounds in Muzishare tube amps too! And we highly recommend that.

And at the topic of tube rolling, KT88 tubes may not be the cheapest tube to roll. But there are still options nonetheless where 6550 and KT90 are some alternatives users can consider. If not, swapping out the smaller 2x 12AU7s and 1x 12AX7 can be great starting fun! 12AU7 alternatives, vintage or reissues, are not very expensive afterall. And while although 12AX7 will cost more, at least the X7 only requires one of it, so a good investment in an improved 12AX7 can go a long way definitely.

In an overall package, the Muzishare X7 is an absolute bargain of a highly capable and great performing KT88 tube amp. It is only just a few years ago when many other more established tube amp makers are marketing KT88s as their highest end of tube amp models. Muzishare, along with a couple of Chinese-made tube amp manufacturers, have over these few years been producing very well-designed KT88 tube amps like the X7 without a hefty price tag, lowering the barrier of entry in financial terms for those who yearn for a KT88 or for the matter, any tube amp. Muzishare’s continual improvement to their amps has allowed X7 to punch way above their weight in recent times as the more affordable price does not relate to a lesser representation of sound. Anyone who have seen the X7 in person will know and understand the quality of the construction is unbelievable for a high-end equipment costing just slightly over two grand Singapore dollars. If you have not, you are more than welcome to make an appointment with us and come down to our shop front to see and hear for yourself why it makes perfect sense, as well as a sound investment (we can jolly well keep it a secret in all honesty but Muzishare and QA have no qualms of sharing that Muzishare amps will only cost more as time goes) to own and enjoy a X7. So why wait. Muzishare X7 listing here.

A little backstory of Muzishare R100

February 4, 2020February 10, 2020 1 Comment

Our Muzishare X5 was the first full-fledge branded factory-made tube amp we brought in around 3-4 years ago in bid to increase its exposure to the general audiophile community in Singapore and the region. A tube amp so well-made and beautiful has no reason not to be considered for anyone seriously into getting his/her first, second or third tube amp.

Muzishare over these years has consistently improved on the quality further, both on the aesthetic front as well as the worksmanship and most importantly, audio quality. Their increasing popularity in China are slowly bringing much awareness outside the region and to the global scene. It is imperative such exposure could do a lot of good to have a focus here in Singapore. And as outlined in our previous post, QA’s effort has finally paid off to have secure the official distributorship of Muzishare tube amps in Singapore from November 2019 onwards.

In recent months, Muzishare has been building a flagship model in order to refresh their tube amp lineup, which has been consistently hovering in these respective tube series – EL84 of X3T, EL34 of X5, KT88 of X7 and 300B of X-300B. While KT88 tube amps are traditionally the onset of big boys, for those graduating from a EL34 tube amp, it is no longer a tube series of amp that holds the charm. Many other manufacturers have come out with various KT88 tube amps and begin saturating the market. The once-powerful and rather exclusive KT88 tube amp is now quite a dime a dozen. Not to undermine KT88 tubes at all for I am still a huge fan of the fat beam tetrode, but above this class is another league that just dwarfs the KT88s (as can be seen in the photo below), big triode tubes, 211/845/805.

***From left to right:*** EL34, 5881, 6L6GC, KT66, KT88 & 845. The first four belongs to the same tube type and are interchangeable in most EL34 amps. Currently using the 5881 Brown base from RCA. But 6L6GC remains my all-time favourite which I could not even bear to use, similar to my reverend 6L6GC Blackplates from RCA that are preciously stowed away.

Line Magnetic is one brand of the Chinese-made amps that have enjoyed stellar reputation worldwide for its indisputable quality. They are one of the early adopters in Chinese tube amp manufacturing to use these giant triode tubes. Their 845 and 805 series of amps are parked at the higher end range of the tube amp chain in many rooms, providing a sound output of the higher echelon.

Muzishare’s flagship model of R100 is heading towards this direction – a hefty tube amp that branches into three different versions of 211/845/805 tubes respectively, allowing customer to choose one that they are most comfortable with. It may seem like a challenging feat for Muzishare in building the R100 as it is only a recent development and lack of previous big triode tube model to back as portfolio. Truth to be told, amps from both Muzishare and Line Magnetic come from the same factory estate in Zhuhai at Guandong, China. Connecting the dots, Muzishare does has a wealth of expertise in building a big triode tube amp, confidently and remarkably, as we are to find out in the next post, where I will dive in details on the Muzishare R100.

Quartz Acoustic is now the official distributor of Muzishare tube amps in Singapore

January 8, 2020February 10, 2020 1 Comment

This news came way earlier but the festive period and orders have been preventing us from announcing!

We are pleased to announce that Quartz Acoustic is now the official distributor for Muzishare tube amps in Singapore!

As some of the customers know, we have always been huge admirers of Muzishare amps. They are just very well-built, fantastic quality in performance and are some of the more beautiful tube amps manufactured from China. Their specifications often edged out amps of the same tube types from competitors which gives their amps an excellent value for money.

Muzishare has a strong following in China, where it is considered relatively high-end for a tube amp brand with extensive features and solid workmanship. Manufactured in Zhu Hai, Guandong, China, the components and parts in Muzishare tube amps consisted of high quality, audiophile-grade of materials, build together with remarkable point-to-point exquisite soldering. External chassis are all well-machined and sand-blasted to a posh exterior, resulting in Muzishare tube amps to be heralded as one of the more beautiful and refined tube amp brands in China. A lesser-known fact is that Muzishare amps are manufactured in the same production factory as the remarkable Line Magnetic.

QA will provide all official queries, sales and support of Muzishare amps through all official channels of contact. 1-year official warranty, as with all our other products, will be provided. We will see to your issues and rectify them, if any, before extending the support to China factory if that need arises, even if your warranty has unfortunately expired. Terms and conditions of warranty and returns still applied. All warranties and supports are only applicable to customers of QA and units purchased from QA. Grey and/or imported sets will not be honoured.

Other than the modded and upgraded version of the X5, we also carry:

X3T – EL84 small-scale tube amp that works very well as a headphone amp as well at S$850
X7 – KT88 tube amp with balanced and phono inputs at S$1,850
R100 – 845 tube amp with plenty of power with balanced and phono inputs at S$3,050

How we test our vacuum tubes

April 28, 2017April 28, 2017 0 Comments

We do our testing of preamp triode tubes with the Tube Imp tube tester specifically on their mutual conductance (or transconductance as some say), measured in the unit Gm. Mutual conductance is a common way of measuring, to be it simply, how much life is left in the tube, by measuring the change in plate current across the change in grid voltage. With operating characteristics from tube data widely available, we chart the readings according to what a specific tube type typically shows.

Every single tube type has their own operating characteristics; hence 12AU7’s Gm rating is different from a 12AX7’s Gm. Looking at different readings of Gms across different tube types may be difficult. So to put it simpler for you, we converted the readings into a percentile. It instantly allows the gauge of the tube’s lifespan to be so much easier. A reading of 92% simply means, theoretically, it has still up to 92% of lifespan.

The two percentage readings you see is because a preamp triode tube is actually comprised of 2 individual amplifying sections. So the reading is for one of each.

There are many talks and hearsays on a pair or quads of tubes got to be balanced/matched to sound the best. Matching only applies to the power tubes like EL34, 6L6GC, KT88, 6550 tube types; basically tubes at the output stage of the amp where current draw of the tubes are kept in similar range. Even so, amps with biasing features are totally not reliant on matched tubes to sound their best. Our tube amps like Yaqin MS-110B and Muzishare X5 have their biasing adjustment built into the amps, so unmatched power tubes are never a problem operating in such circumstances. What are the advantages then? Money is saved! Probably too much mark-up is done to tubes being sold just because they are matched. We are not saying that is not important, but if your tube amp has easy bias adjustment, there is certainly no need to spend an extra premium on power tubes being matched which we can only trust some seller to really do the matching.

With matching not applicable to preamp tubes, we then talk about them being balanced. As previously mentioned, a preamp triode tube has 2 amplifying sections in each tube. So a balanced preamp triode tube means the 2 readings within it is very close to each other. So how much of a variation is considered balanced? Well, the good news is this ‘balanced’ attribute of a preamp triode tube is actually not that a big issue in determining the good from the bad. Still, a range of not more than 15% difference between the two readings of a preamp tube is more than fine. And our tubes listed are definitely within that range.

In conclusion, do take precautionary note on getting tubes from sources that advertised their preamp triode tubes are matched, as there is no need for that as far as preamp triode tubes are concerned in audiophile devices. While balanced preamp triode tubes are desirable, if the extra premiums are paid just for them being balanced, the cheaper alternative with some slight variation is probably the better deal.

A Smooth EL34 Tube Amp for both your Speakers and Headphones

April 18, 2017July 5, 2019 2 Comments

Muzishare is a brand that enjoys quite a bit of popularity worldwide. It is hard not to, when it has the design appeal and construction of a fine tube amp, and performing just as well as it looks. X5 from Muzishare possesses all that great quality and carrying the EL34s as its power tubes, we do need further decision to bring that in as the first Muzishare tube amp on sale at QA.

EL34 tube is a very versatile tube type in terms of the varieties it has for replacement and rolling. Main sound signature for EL34 is the smooth and sweet midrange it extends to the upper region of the frequency spectrums. Vocal lovers, this tube type is your best companion! Be mesmerised by your favourite artistes singing with a true presentation in front of you, probably even catching the breathing done!

Getting more details of this amp is entirely possible if better quality of EL34s are inserted in or with rolling of 6L6G/6L6GC tubes. Your listening experience may be transformed with a livelier soundstage and added crisp. If you find yourself having 5881s instead, no problem too. These military tube variants are acceptable into this Muzishare X5 tube amp as well. That is what we called flexibility.

Pre-amp section of the tube amp is driven by 2x 12AU7 and 2x 12AX7 tubes. Easily available with different brands and vintage types too, rolling these tubes will add on to the fun of creating a sound flavour to your liking!

With so many tubes available for rolling, biasing of the tubes is important to ensure the tubes put in are always operating at their best settings. X5 brings tube biasing to a great level of ease, with just a flat-head screwdriver needed. The front panel of the amp is a VU-meter lookalike that negates the requirement of a multimeter. That is the bias meter used for gauging the correct amount of current going to the tubes. There is a knob on the top of the amp on the right-hand side indicating which tube to select to while doing the bias, and that is also indicative of the reading with respect to the tube it measures off. Biasing is simply adjusting the adjustment screws on the side of the top panel respective to the tubes labelled until the needle in the bias meter points to the accepted range.

To the right of the bias meter are two fantastically-made aluminium knobs from CNC machining. Controlling the volume is a smooth act, while changing between the input settings is a solid affair. With 4 inputs selection to plug in and choose from, you can plug in a wide range of sources to play your favourite music from!

Two wonderful features of this X5 are found to the left of the bias meter. A 6.35mm headphone out ensures this amp not only powers speakers, but it can also drive headphones of any sizes and demands without difficulties at all! Dedicated tube-powered headphone amps can cost close to what this X5 is offering. At the same time, they may use tubes less commonly found for replacement or rolling. This restricts the headphone amp from performing to a variety of sound flavours. An amp like X5 almost brings the best of all worlds in giving you one package with exceeding performance, cost and versatility.

The switch beside the headphone out is to toggle between Ultralinear and Triode mode of the amp. These two modes are common connections within the circuit of tube amps that provides different power outputs and also different flavours of sounds. Ultralinear has a high power output, i.e higher gain. It boots a higher dynamism to the sounds, like a SS amp in some sense. This mode is great for orchestra, ensemble and classical genre of music.

Triode mode on the hand has a lower power output. Volume control tends to need to be higher for similar sound level appreciation. However, this mode has an emphasis to midrange of the music. Hence it is a very popular mode chosen for vocal genres like pop and opera. Either mode can be toggled on the fly even with the music being played. A-B auditioning can be done to see which mode is preferred.

At the back panel are high-quality binding posts and RCA jacks that are bound to secure all connections hooked to them. RCA caps are provided to cover whichever ports not used to prevent oxidisation of the contacts. A voltage switch at the back allows the X5 to be usable anywhere in the wold regardless of 110v or 220v AC.

Weighing close to 18kg, the entire amp was constructed out of solid materials like steel and aluminium. The front panel is already one 10mm thick aluminium. The rest of the chassis is an enclosure well-glazed with sand-blasted glittering gloss that does not leave fingerprints. Quality of the construction extended to the cage. No tools are needed to fix it over the tubes. With a banana-plug-like feature, the cage can be affixed securely to the amp. Removing it from the socket is just as easy and quick. Brilliant!

Finally, the other piece of well-machined hardware is the remote control. Crafted entirely out of aluminium, it matches excellent with aesthetics of X5. While it only offers volume adjustment and mute/unmute operation, having that remote on your hands is undoubtedly a convenient in controlling the volumes while seated comfortably on your listening spot.