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Post by kauai82 on Jan 19, 2017 19:22:54 GMT -5
With the unexpected demise of my Emotiva 8100 AVR receiver early this week that must be sent into Emotiva service center (luckily under warranty, but at the cost of $61 dollars to me in shipping from So. Ca. ) . I was in a position of having no tunes for a period of four or five weeks since Emo's service center is backed up currently as stated in their email to me with the directions to send the unit to them. I normally have an extra vintage receiver or integrated amp around the house as I sell them on eBay that I could plug into the family room system, but nothing at this time. See my Signature. I looked on eBay, but no luck with anything that was not way over priced. I did not want to tear apart one of my other systems so I was starting to panic on having tunes downstairs. I remembered that I had my little 25 watt Monoprice hybrid Tube Amp that I use in the garage, but that only had 12 watts per channel and would not drive my DIY Tango speakers in the family room system. However, I did remember that Monoprice had come out with a "big brother " to my little amp. Looked on Monoprice web site and sure enough there it was a 50 watt (into 4 ohm) a channel hybrid integrated tube amp. That means that the preamp tube driven with a solid state amplifier section. I was still a little hesitant to purchase the big brother amp. I had purchased the 25 watt Monoprice amp about a year and half ago and had some real problems with Monoprice quality control as the first two unit I got had a hum in the headphone section and one that the headphone jack did not work at all. There is an old thread on my journey in cheap Chinese preamps. However, Monoprice is headquartered only about ten miles from my house and they always have took care of me in the past so I figured for $200 lets try out the big brother unit.
Monoprice sells the 25 watt version of this amp for $150. It has a total output of 12 watts per channel and includes a headphone jack and Bluetooth connectivity. In the preamp section of the unit it comes with two 6n1 and two 6p15 vacuum tubes. In the 50 watt version you get a bigger base and a three pounds heaver unit. The preamp section has two 6n1 and two 6p1 tubes. I am not sure what the difference is from the 6p15 tube to the 6p1 tubes. I will have to research that for a latter update. In the big brother version you lose the headphone jack, but gain a RCA output jacks that can be used to run a subwoofer or use the tube amp as strictly a preamp. You also get of course more watts per channel and I believe better build quality. It also has Bluetooth as the lower priced version. I think that Monoprice and its Chinese manufacturer learned from it's first problems with its 25 watt version as I had no problems with the newer 50 watt version.
The new 50 watt version came well packaged and the tubes were preinstalled. Took just a couple of minutes to get the unit hooked up in my family room system. I have in the last few years used my family room system primarily for 2.1 channel sound. I normally surf the internet and keep the dogs company as they are not allowed upstairs. My critical listening and multichannel audio/ video is upstairs. I still have to have decent sound from the family room system, but the room is not acoustically good and the wife does not want any acoustic treatments. I was not sure what to expect from my new Monoprice Tube Amp, I knew it should sound okay at the least because of my experience with its sibling.
Wow, was I pleasantly surprised at the SQ. The amp puts out much better than expected SQ. I believe that it is better than the Fusion 8100 at normal to slightly high listening volumes. The Fusion 8100 wins at very high volume levels in sound quality due to its 110 watts into two channel specs. At $200 this is a very pleasant surprise. I will give more listening impressions and a comparison with my Primaluna Prologue One integrated amp in about a week. Matt
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Post by leonski on Jan 19, 2017 19:54:57 GMT -5
The difference between 25 watts and 50 watts TOTAL is only 3db. Barely enough to bother with.
I use a PE amp in the Garage. Yep, the DTA-1 which is a claimed 9x2 @4ohms is perfect with higher sensitivity speakers.
The Parts Express amp can be powered by batteries or the supplied Wall Wart.
And yes, it Will only play so-loud, which is fine for what I'm using it for.
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Post by kauai82 on Jan 30, 2017 15:29:36 GMT -5
Well I have been listening for the last 10 days and I am still very impressed with this little hybrid tube amp for $200 from Monoprice. The Bluetooth works very well and the sound quality from my FLAC files from my HP laptop to XDA-2 to Monoprice is very good. I did hook up my Primaluna downstairs in the family room system and compared the two amps. I must say that the Primaluna does give a more detailed imaging (as it should for the money ) and a little more bass with its KT88 tubes than the Monoprice. It was much closer in SQ than I was expecting. I believe because my Tango DIY kit speakers have aluminum drivers in both the tweeter and mid woofer, RS28a and RS180 drivers for you Parts Express fans, combined with my acoustically challenged family room I am now looking for a little warmer sound than I have currently. I will have to think my upgrade path for the family room a little differently than I was originally thinking. I might want to go with a truly integrated tube amp like the Primaluna, but I can't justify spending that much and I love the sound of the Primaluna in the office. Maybe a used Yaqin integrated amp ? This is why my wife hates this hobby --I am always looking for a little bit better sound or different sound. Matt
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Post by leonski on Jan 30, 2017 15:39:55 GMT -5
Great news. The only thing I'd be careful of is if an amp uses a rare or Very Expensive tube.
Other than that? ENJOY your new amp.
Don't forget that pre-loved gear may be a way to try something and if you don't like it, sell it for little to no loss, other than maybe shipping.
That PrimaLuna might be less $$$ than you first thought.
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Post by charlieeco on Jan 30, 2017 16:04:48 GMT -5
Well I have been listening for the last 10 days and I am still very impressed with this little hybrid tube amp for $200 from Monoprice. The Bluetooth works very well and the sound quality from my FLAC files from my HP laptop to XDA-2 to Monoprice is very good. I did hook up my Primaluna downstairs in the family room system and compared the two amps. I must say that the Primaluna does give a more detailed imaging (as it should for the money ) and a little more bass with its KT88 tubes than the Monoprice. It was much closer in SQ than I was expecting. I believe because my Tango DIY kit speakers have aluminum drivers in both the tweeter and mid woofer, RS28a and RS180 drivers for you Parts Express fans, combined with my acoustically challenged family room I am now looking for a little warmer sound than I have currently. I will have to think my upgrade path for the family room a little differently than I was originally thinking. I might want to go with a truly integrated tube amp like the Primaluna, but I can't justify spending that much and I love the sound of the Primaluna in the office. Maybe a used Yaqin integrated amp ? This is why my wife hates this hobby --I am always looking for a little bit better sound or different sound. Matt |
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Post by garbulky on Jan 30, 2017 16:17:11 GMT -5
Well I have been listening for the last 10 days and I am still very impressed with this little hybrid tube amp for $200 from Monoprice. The Bluetooth works very well and the sound quality from my FLAC files from my HP laptop to XDA-2 to Monoprice is very good. I did hook up my Primaluna downstairs in the family room system and compared the two amps. I must say that the Primaluna does give a more detailed imaging (as it should for the money ) and a little more bass with its KT88 tubes than the Monoprice. It was much closer in SQ than I was expecting. I believe because my Tango DIY kit speakers have aluminum drivers in both the tweeter and mid woofer, RS28a and RS180 drivers for you Parts Express fans, combined with my acoustically challenged family room I am now looking for a little warmer sound than I have currently. I will have to think my upgrade path for the family room a little differently than I was originally thinking. I might want to go with a truly integrated tube amp like the Primaluna, but I can't justify spending that much and I love the sound of the Primaluna in the office. Maybe a used Yaqin integrated amp ? This is why my wife hates this hobby --I am always looking for a little bit better sound or different sound. Matt I know what you mean. In the beginning that's what I was doing. What I was doing was going for incrementally better things. And then just a bit more etc. I find I get a lot more satisfaction in taking time to save up, doing some research and going big - with the expectation that the sound gets significantly better. And since I do try to go big, then my expectations are higher. This way there's no justification "well that's what I should expect for what I paid". It's good or go home. |
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Post by Deleted on Jan 31, 2017 10:04:02 GMT -5
Well I have been listening for the last 10 days and I am still very impressed with this little hybrid tube amp for $200 from Monoprice. The Bluetooth works very well and the sound quality from my FLAC files from my HP laptop to XDA-2 to Monoprice is very good. I did hook up my Primaluna downstairs in the family room system and compared the two amps. I must say that the Primaluna does give a more detailed imaging (as it should for the money ) and a little more bass with its KT88 tubes than the Monoprice. It was much closer in SQ than I was expecting. I believe because my Tango DIY kit speakers have aluminum drivers in both the tweeter and mid woofer, RS28a and RS180 drivers for you Parts Express fans, combined with my acoustically challenged family room I am now looking for a little warmer sound than I have currently. I will have to think my upgrade path for the family room a little differently than I was originally thinking. I might want to go with a truly integrated tube amp like the Primaluna, but I can't justify spending that much and I love the sound of the Primaluna in the office. Maybe a used Yaqin integrated amp ? This is why my wife hates this hobby --I am always looking for a little bit better sound or different sound. Matt Keep in mind, the PrimaLuna is an actual tube integrated amplifier, with a tube power amplifier section, while the Monoprice unit is a two-channel solid state amplifier with only a tube preamp section for "color". They both will provide some amount of that tube "color" but the Primaluna integrated will likely have even more of it since the entire system is tube-based. I would also expect that the PrimaLuna is "better" enough in sound, materials, and workmanship, and better supported by the manufacturer with parts and repair, while the Monoprice unit would be more of a "throw-away" if it went south. All that being said as preamble, I am interested to hear kauai82's response on the question of the sound. |
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Post by Loop 7 on Jan 31, 2017 11:02:23 GMT -5
The difference between 25 watts and 50 watts TOTAL is only 3db. Barely enough to bother with. I use a PE amp in the Garage. Yep, the DTA-1 which is a claimed 9x2 @4ohms is perfect with higher sensitivity speakers. The Parts Express amp can be powered by batteries or the supplied Wall Wart. And yes, it Will only play so-loud, which is fine for what I'm using it for. I wonder if Parts Express amps are the most common garage and workshop amps? Two pals and myself use them. |
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Post by kauai82 on Jan 31, 2017 11:10:12 GMT -5
Great news. The only thing I'd be careful of is if an amp uses a rare or Very Expensive tube. Other than that? ENJOY your new amp. Don't forget that pre-loved gear may be a way to try something and if you don't like it, sell it for little to no loss, other than maybe shipping. That PrimaLuna might be less $$$ than you first thought. The tubes used in the Monoprice are very easy to buy online and very inexpensive. I am thinking of upgrading the 6n2 tube to a matched pair for a cost of $30. The 6P1 are about $5 apiece and I will buy a back up pair. I did buy my Primaluna Prologue One used for about $850 with Primaluna tubes with low hours on them. A real steal. I would not be able to buy the Primaluna at regular retail prices. I might be looking into a used Yaqin integrated tube amp in the future. Matt |
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Post by kauai82 on Jan 31, 2017 11:31:36 GMT -5
Well I have been listening for the last 10 days and I am still very impressed with this little hybrid tube amp for $200 from Monoprice. The Bluetooth works very well and the sound quality from my FLAC files from my HP laptop to XDA-2 to Monoprice is very good. I did hook up my Primaluna downstairs in the family room system and compared the two amps. I must say that the Primaluna does give a more detailed imaging (as it should for the money ) and a little more bass with its KT88 tubes than the Monoprice. It was much closer in SQ than I was expecting. I believe because my Tango DIY kit speakers have aluminum drivers in both the tweeter and mid woofer, RS28a and RS180 drivers for you Parts Express fans, combined with my acoustically challenged family room I am now looking for a little warmer sound than I have currently. I will have to think my upgrade path for the family room a little differently than I was originally thinking. I might want to go with a truly integrated tube amp like the Primaluna, but I can't justify spending that much and I love the sound of the Primaluna in the office. Maybe a used Yaqin integrated amp ? This is why my wife hates this hobby --I am always looking for a little bit better sound or different sound. Matt That is the million dollar question. I bought my Primaluna Prologue One used for $850 on line. As I have stated many times love the sound of my Primaluna with both EL34 and KT88 output tubes. If I had paid full price for the Primaluna amp I might question my decision to spend that much money. The Monoprice 50watt is fairly close in sound quality to the Primaluna as I stated before. Because the Monoprice amp is a hybrid with SS amp you don't get the full tube sound effect that you do with the Primaluna. However, the difference in SQ is subtle, but important. I would say in my opinion that for comparison sake , the Monoprice is about 92% of the SQ of the Primaluna. Is that 8% difference worth $1600 dollars ? For the third system in my house in a family room that is very reflective and I don't really use often for critical listening I would have to say no. For my office system I where I have a better listening environment and do more critical listening, possibly. However, since I bought my PL amp used for $850 I would say that 5-8% improvement is well worth the extra $650 that I paid for the PL amp. Of course that is my opinion and your YMMV. Matt |
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Post by kauai82 on Jan 31, 2017 11:58:30 GMT -5
Hi Kauai82 could you hear the $1,600 difference between them? Keep in mind, the PrimaLuna is an actual tube integrated amplifier, with a tube power amplifier section, while the Monoprice unit is a two-channel solid state amplifier with only a tube preamp section for "color". They both will provide some amount of that tube "color" but the Primaluna integrated will likely have even more of it since the entire system is tube-based. I would also expect that the PrimaLuna is "better" enough in sound, materials, and workmanship, and better supported by the manufacturer with parts and repair, while the Monoprice unit would be more of a "throw-away" if it went south. All that being said as preamble, I am interested to hear kauai82's response on the question of the sound. One of the reason that I bought the Primaluna integrated amp was that the West Coast representative is Upscale Audio not more than 30 minutes from my house. I can get the unit fixed if it goes south--replacement tubes etc. Also, I knew what the amp sounded like on a visit to Upscale Audio so I knew the SQ was what I was looking for in my office system. Those benefits have little to do with SQ, but a lot to do with keeping the amp for years to come working in great shape. Since I and my wife are retired, my audio budget has shrunk substantially than it was just a few years ago. I have to make my audio dollar go as far as I can. I would have to say that for the full retail price of $1800 I would not be able to justify buying the Primaluna over the Monoprice 50watt unit. There is not enough difference in SQ quality in my opinion and current audio budget to justify the $1600 dollars difference in retail price of the units. See post earlier in the thread on my thoughts on this. True after the one year warranty on the Monoprice unit --it becomes a throw away unit. But for the price of the Monoprice unit you can replace it many times if it fails and still not come close to the original retail price of the Primaluna. Both units at the price points I purchased them for $850 for the PL and $200 for the Monoprice are fantastic bargains in SQ and well worth the price I paid for them and I am very happy that I own both of them. Matt |
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Post by copperpipe on Jan 31, 2017 12:37:30 GMT -5
One of the downsides to tube amps is the power consumption and heat output. Since the monoprice amp section is SS, does it escape that particular downside? Or does it still get very hot?
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Post by kauai82 on Jan 31, 2017 13:21:44 GMT -5
One of the downsides to tube amps is the power consumption and heat output. Since the monoprice amp section is SS, does it escape that particular downside? Or does it still get very hot? No the Monoprice is fairly cool. The tubes get hot but they have little metal cage protectors around them. The Primaluna can heat up the room, especially the KT88 output tubes I am using now. Matt |
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Post by leonski on Jan 31, 2017 13:59:29 GMT -5
Simple matter to measure power consumption using an Easily Available Kill-A-Watt meter. Maybe 20$ to 25$ at the local home store or online.
Just assume that while producing NO sound that all the input energy is going up in heat.
If you measure, please post some results. I think some people would be curious.
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KeithL
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Post by KeithL on Jan 31, 2017 14:28:40 GMT -5
Big power tubes tend to make a lot of heat, while little preamp "peanut" tubes really don't. One of the downsides to tube amps is the power consumption and heat output. Since the monoprice amp section is SS, does it escape that particular downside? Or does it still get very hot? |
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Post by copperpipe on Jan 31, 2017 18:16:14 GMT -5
Next question  I leave my 2 mini-x's permanently in standby mode; when it senses a signal it turns on, then turns off after 5 minutes of no sound. Quite often through the entire day, they will cycle on and off about 10+ times in the day. I've never worried about the lifetime of the mini's mainly because I'm assuming that this type of cyling doesn't hurt them significantly. But what about tube amps... do they get ornery if cycled on/off too much? |
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Post by charlieeco on Jan 31, 2017 21:49:01 GMT -5
Hi Kauai82 could you hear the $1,600 difference between them? That is the million dollar question. I bought my Primaluna Prologue One used for $850 on line. As I have stated many times love the sound of my Primaluna with both EL34 and KT88 output tubes. If I had paid full price for the Primaluna amp I might question my decision to spend that much money. The Monoprice 50watt is fairly close in sound quality to the Primaluna as I stated before. Because the Monoprice amp is a hybrid with SS amp you don't get the full tube sound effect that you do with the Primaluna. However, the difference in SQ is subtle, but important. I would say in my opinion that for comparison sake , the Monoprice is about 92% of the SQ of the Primaluna. Is that 8% difference worth $1600 dollars ? For the third system in my house in a family room that is very reflective and I don't really use often for critical listening I would have to say no. For my office system I where I have a better listening environment and do more critical listening, possibly. However, since I bought my PL amp used for $850 I would say that 5-8% improvement is well worth the extra $650 that I paid for the PL amp. Of course that is my opinion and your YMMV. Matt0 Pretty clear response, thanks Matt, I´ll try the Monoprice when on sale!! just for the fun of it. |
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Post by leonski on Jan 31, 2017 22:36:43 GMT -5
WHY do tubes fail? I wonder if, when turning off a tube amp, you could IDLE the heaters at about 1/2 voltage? That might extend tube life and should also get near 'instant on'.
Do tubes fail like Incandescent lamps, which fail for me usually when turned 'on'?
Auto bias helps tube life, too. Letting a manual bias setup go or simply never checking it might adversly impact tube life.
Are tube amps better off if left on? I don't know, but I don't think so.
If I lived some place that had a cold winter, I might have a winter amp and a summer amp! Tubes for winter to help keep the place warm.
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Post by Boomzilla on Feb 1, 2017 6:51:49 GMT -5
Tube amps are not space heaters. Don't leave them on all the time. Tubes DO have a finite life span, with many things affecting that life. Some circuits run their tubes hotter than others (more bias). The sound changes, depending on the circuit. The hotter the tube is run, generally, the shorter the tube life.
The problem with tubes isn't with tube aging, but with tube failure. When a tube fails, it has the potential to temporarily cause a voltage surge in the amplifier that can damage other tubes. The best solution I've seen is for each tube to have an independent fuse.
Rectifier tube failure can sometimes cause damage to the amp as well. The best tube amps offer solid-state rectification with a delay so that at turn-on, the tube heaters have the tubes hot before the rectified B+ voltage is applied.
The better tube amps also have ventilation holes around each and every tube for convective cooling.
Another tube-amp-killer is power blips. Most tube amps don't gracefully tolerate rapid on-off cycles. This can be dealt with by either using a UPS or by having a time-delay in the amp that prevents rapid re-energization after turn off.
Auto-bias is also a great convenience feature. This isn't the same as "fixed bias." With inexpensive tube amps, the tube characteristics are assumed to remain constant, and bias voltage is supplied with a fixed resistor. With slightly better tube amps, the user can measure the bias with a volt-ohm meter and manually adjust a variable resistor to set the bias. The best tube amps automatically and continuously measure the amplification from each tube and automatically adjust the bias to that individual tube to maintain equal gain throughout the life of the tube.
And finally, chassis layout contributes to tube life. The best designs keep the (hottest) output tubes away from the transformers and from other tubes for the most even cooling. Bad designs use an existing "legacy" chassis where no thought was given to heat dissipation.
In theory, good design costs not significantly more than bad design. But few inexpensive amps have the features mentioned above.
Boom
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KeithL
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Post by KeithL on Feb 1, 2017 9:44:26 GMT -5
Unfortunately, there are also "issues" with turning tubes on and off too often. Because tubes run so hot, they go through a rather extreme temperature cycle as they heat up and cool down. As with incandescent light bulbs, tubes, and especially power tubes, "wear out" depending on how many hours they're run, but they also experience a different sort of wear each time they heat up and cool down. Therefore, while it doesn't make sense to leave them on all the time, you also shouldn't turn them on and then off again to run them for a half hour either. Some audiophiles also insist that some tube amps need to "warm up" for a long time before they sound right. While I would agree that solid state rectifiers are preferable, one advantage of the old tube rectifiers was that, because they warm up slowly, they have a built-in delay on the B+ voltage. (A final note is that tube rectifiers have a relatively high pass impedance, which means that they yield a "softer" power supply, which sags more under load. While, from a circuit design perspective, this is a weakness, it's also why unregulated tube rectified power supplies can cause an amplifier to sound different than the same amplifier with a solid state or regulated power supply.) I would also like to correct one misunderstanding about cathode bias (which is when you bias the tube with a cathode resistor bypassed by a capacitor). That type of circuitry does NOT "assume that tubes never change" - in fact it's rather the opposite - and the concept, while simple, is quite elegant. Because the grid of the tube is referenced to ground, but the voltage across the cathode bias resistor is determined by the current through the tube, the circuit actually continually adjusts the bias for the condition of the tube. This adjustment is inherent in the circuit design itself. If the tube starts to draw more current, the voltage drop across the resistor goes up, which raises the bias, which reduces the current. That simple old circuit also compensates for both tube wear and differences between individual tubes... and is somewhat protected against damage if the tube actually fails. (If one of those fancy new auto-bias circuits fails, it's pretty much a doomsday scenario.) The drawback to cathode bias is that, while it's an elegant feedback system, it's still not as precise as the more modern auto-bias systems.... so the newer systems can squeeze slightly better performance out of tubes - and adjust over a wider range of variation - especially if they aren't well matched to begin with. I should also mention the other disadvantage of cathode bias - which is efficiency. The bias resistor "eats up" about 5% to 10% of the output power capability of the tube. This is meaningless on a preamp tube, but may be significant on a power tube where the designer is trying to squeeze every watt out of the tube for better ratings. One of the biggest down-sides of modern tube designs is simply that many modern designers don't actually know what they're doing.... and a lot of what was learned years ago seems to have been forgotten (or is simply ignored for other reasons). Tube amps are not space heaters. Don't leave them on all the time. Tubes DO have a finite life span, with many things affecting that life. Some circuits run their tubes hotter than others (more bias). The sound changes, depending on the circuit. The hotter the tube is run, generally, the shorter the tube life. The problem with tubes isn't with tube aging, but with tube failure. When a tube fails, it has the potential to temporarily cause a voltage surge in the amplifier that can damage other tubes. The best solution I've seen is for each tube to have an independent fuse. Rectifier tube failure can sometimes cause damage to the amp as well. The best tube amps offer solid-state rectification with a delay so that at turn-on, the tube heaters have the tubes hot before the rectified B+ voltage is applied. The better tube amps also have ventilation holes around each and every tube for convective cooling. Another tube-amp-killer is power blips. Most tube amps don't gracefully tolerate rapid on-off cycles. This can be dealt with by either using a UPS or by having a time-delay in the amp that prevents rapid re-energization after turn off. Auto-bias is also a great convenience feature. This isn't the same as "fixed bias." With inexpensive tube amps, the tube characteristics are assumed to remain constant, and bias voltage is supplied with a fixed resistor. With slightly better tube amps, the user can measure the bias with a volt-ohm meter and manually adjust a variable resistor to set the bias. The best tube amps automatically and continuously measure the amplification from each tube and automatically adjust the bias to that individual tube to maintain equal gain throughout the life of the tube. And finally, chassis layout contributes to tube life. The best designs keep the (hottest) output tubes away from the transformers and from other tubes for the most even cooling. Bad designs use an existing "legacy" chassis where no thought was given to heat dissipation. In theory, good design costs not significantly more than bad design. But few inexpensive amps have the features mentioned above. Boom |
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