Just bought one of these shipped from Hong Kong. It's branded "Oldchen". Yes its a very nice amp. I got great sound right out of the box only to improve after 100 hrs . Thanks for reviewing this amp under a microscope. I also have a Jolida 502brc and this 300b Amp is comparable in quality and articulate in sound. With a tube up grade the enhancement is a pure audiophile dream.
the white stuff is liquid electrical tape. It is not corona putty, which is used only on high voltage to prevent corona arch discharging. . The liquid electrical tape is there, to prevent terminal corrosion, and accidental shorting by people poking around in there with screw drivers , like you.
My theory is that the white goop is applied specifically to discourage one from modifying the amp. Removing it will probably void the warranty. I am building an Elekit TU-8300R which looks to have a similar design. My amp will also let me use 6550 (KT88) tubes as well as the 300B. Looks like you have a good amp. Thanks for help keeping analogue audio alive.
I got a NAD that looks exactly like yours. Mine is rated at 80 w per ch. It sounds good, but treble is a little "wirey" compared to my more natural treble on my way cheaper 200 w per ch. jaycar amp. And the jaycar has better bass. But the NAD does sound "alive", maybe that's why they are liked so much (but just a bit more "transistory" in the treble. lol And $800 is cheap for a tube amp. who cares if it's not that powerful. The sound would be amazing, going by your reaction. I had a tube amp (an old Sansui) looked much like your old tube amp. But I had a fairly gutless tube amp as well (small size old school one) and it was less powerful but miles better in sound than the old Sansui. Your NAD started my rant. I use my NAD sometimes but usually it just sits around, but I would never sell it. Sound system nuts always need a second amp just in case one fails, and for parties elsewhere occasionally.
they also said in the description that the VU meters show tube current in real time, which i find odd because VU meter looks to show only db scale, can you tell me if your amp shows tube current or is it db scale? another concern is the shipping, and did you have to pay a customs fee which is sepperate from the shipping charge. I like the looks of the 300B tubes, right now this amp is selling for $849 on ebay but they also have the Yaqin MC-100B for the same price, i do like what i hear about the MC-100B but it does have a circuit board but it is user biased which i like.
I have presently three SE amps: Will Vincent 2A3/45, Sanei 2A3/45 and a custom-built 6BG6 tetrode. All three amps will drive my Klipsch Heresies and DCM Time Windows to adequate listening levels. Proper speaker matching is important with low-power tube amps! For my Quad 57's and Rogers LS3/5A's I prefer 20+ watts of PP power - Dynaco ST70 and Paoli/Dyna Mk3's.
The left and right imbalance could also be due to the volume pot having some tolerance. See if you can add a high value parallel resistor from center to either ends to bring that in sync with the other channel.
Great review. I have the same model amp, and I agree with your description of the sound. I like the sound of Gemtune GP-01 300B with sensitive speakers better than my hybrid tube/solid state, $1,895 Croft Phono Integrated amp, which is itself a very good integrated amp (a Stereophile Class B Recommended Component for several years). The Croft does have better control of the bass with more impact on full range speakers, as it should with its MOSFET solid state output stages, and 45 Wpch output power. However, for my flea watt SET amps like the Gemtune, I prefer to use an active subwoofer that has a solid state amplifier driving the subwoofer, so that the SET amp only has to drive the high efficiency speakers above the subwoofer's cross-over frequency, which in my current setup is 100 Hz. This type of setup provides the low bass control and impact of the solid state amp married to the rich upper bass and mid-range, extended sweet treble, and spacious soundstage of the SET amp. To make this work, one must be willing to spend the time and effort in listening and tweaking the subwoofer cross-over frequency, level and polarity until the transition between the subwoofer and the speakers sounds seamless. My Gemtune amp also has a channel imbalance, which I can hear as a steering of singers and instruments off of center when they are supposed to be centered between the speakers. I corrected this using a high quality attenuator on the input of the louder channel. Another way to handle this is to use a preamp with a balance control with this amp. Some source components may have channel level controls, like my Oppo blu-ray player, which can be used to correct the channel imbalance. However, most of my other sources do not have channel level controls nor balance controls, hence my using an attenuator.
Would this be a good choice for Altec 755A full range drivers mounted in custom cabinets without crossovers? Thanks in advance. Great video by the way.
Try swapping power tubes. See if that follows. If it doesn't, then you may want to check all of your electrolytic capacitors using an ESR meter. I'm thinking that is probably your problem.
@stereopolice you mentioned that this tube amp and other tube amps,dont do as well with the lows as solid state.Can you recommend a tube amp that does well through the whole frequency range?Or a hybrid that does?
wonder if you can help clear up some confusion i am getting from the Doukmall store on ebay, they have this amp forsale and one that is simular to it, i asked if the amp is auto biased or user biased and the reply that i got was just (biased) so i messaged them again and had to explain it to them in more detail, and they replied back (also self biased) so at this point im wondering how i can get the truth out of these guys, then they said it was user biased, but in the description and specs they put on the ebay site there was no mention of how its biased, so can YOU tell me if its ( self biasing or user biased) because judging by there photos i could not see any adjustment screws or ports for multimeter probes.
You should work to Stereophile. How can you compare a PP with a SE, not to mention the SE has OPTs (impedance matching devices). So are you listening to the 300Bs or the transformers? Are you trying to mislead buyers? Otherwise - very good review.
Could you suggest some affordable speakers to pair with such an amplifier? Its an uncomfortable feeling when I mention decibels, spl, thd, etc and the salespeople dont know what the terms are or they reply with no one uses those terms anymore.
John Thornton John, speakers are an iffy thing; we all hear things so differently. I like full range, and use Fostex for listening. However, I'd recommend some classic Klipsch ... get on ebay and see what's for sale.
I did tons of research for tube amp/speaker matching. Since its an exclusive group that enjoys it.. speakers are hard to find manufactured unless you wanna pay good $$. DIY is the way to go. As low as $40 a pair for Atlas full range 8" with whizzer, to $2600 for a pair A series Lowthers similar size. You can buy cabinets from parts express..(love the folded horn) or be creative... that is what I did.. out ofold book shelves and cabinets from the thrift stores. ( why buy new wood/) After all those old shelves from thrift stores are REAL wood and cheap. I had fun building them but can never enjoy them. Friends, family and neighbors are always buying off from me.. ( I just cant say no..lol).
Thanks Lord for nerd tech geeks so we don't just have to trust some stranger's ears !!!...and this one can even translate all the chinese tech to street English ! Awesome video man !!
Hi Great review . Thank you. I am thinking to buy this as never heard 300B SET. I have David Bogen DB-212 Vintage amplifier and Klipsch Heresy I Vintage from 1982. I love the Bogen but its not SET . Are you still use yours? One important question as like simple circuit does this amplifier has Global Negative Feedback? As I heard that Negative feedback degrades quality. Your valued answer is much apreciated.
Agreed, typically imbalance...can.... come from non-matching tubes. However, if this tube amp allows u to adjust the tube BIAS, then I would start there. Seems like u fixed this w balancing pots....but since u like this tube amp so much, do additional research from currents users. See what tubes they rolled to. My Yaqin MC100b allows u adjust the bias on the tubes. Honestly, I would not even think about buying a tube amp, unless it had user adjustable bias, via screwdriver and a volt meter. Tubes notoriously fade in performance over time,and also certain makes and models of tubes need bias set specifically when paired with a specific tube amp ...really only takes a few minutes every 6 months, less for more frequent daily usage..but once u roll in BETTER tubes...could be old stock vintage tubes, or newer matched tubes.....wow...u think your tube amp sounds great now...roll tubes and u reach phenomenal listening levels, especially playing vinyl, or even using a tube buffer w CDs or music streamer. High efficiency speakers are a must...if u r a basshead, can always add a subwoofer to a pair of great book shelf speakers. Have fun.
specs for response above human hearing range, are useless- what matters is how good it sounds to the human ear. checking a stereo with a meter, is like sizing up a woman with a tape measure. you can get great measurements, and the package may look awesome on the surface, but you may end up with something you can't live with for more than a weekend. her "personality", tone, and habits may be horrible.same with stereos.
AWESOME comparison man, I second that ;) PS any idea weather Parallel Single Ended amplifiers sound any different than Single Ended amplifiers? this Parallel tube amp uses 2 valves per channel in paralel for more power: www.amazon.com/YAQIN-MC-550C-Vacuum-Integrated-Amplifier/dp/B00A7IZPGY
the ultimate stereo is a single ended, period. the downside is, lower volume, bass hit, power. the upside is, great detail, depth, soundstage, realism, no listening fatique. an added perk, a nice single ended stereo saves you ears from volume abuse.
Easy way to know an electronic component is from China, all the glue they us everywhere. But, the CCP thanks you for your purchase as it helps them with their important work (keeping their people under their control).
Just bought one of these shipped from Hong Kong. It's branded "Oldchen". Yes its a very nice amp. I got great sound right out of the box only to improve after 100 hrs . Thanks for reviewing this amp under a microscope. I also have a Jolida 502brc and this 300b
Amp is comparable in quality and articulate in sound. With a tube up
grade the enhancement is a pure audiophile dream.
the white stuff is liquid electrical tape. It is not corona putty, which is used only on high voltage to prevent corona arch discharging. . The liquid electrical tape is there, to prevent terminal corrosion, and accidental shorting by people poking around in there with screw drivers , like you.
White Protected solder from cracking with age, very clean build.
I'd like to invite you to visit my stereo shop. I hope you can come
www.hiendchina.com
My theory is that the white goop is applied specifically to discourage one from modifying the amp. Removing it will probably void the warranty. I am building an Elekit TU-8300R which looks to have a similar design. My amp will also let me use 6550 (KT88) tubes as well as the 300B. Looks like you have a good amp. Thanks for help keeping analogue audio alive.
Can't thank you enough for this thorough review!
I got a NAD that looks exactly like yours. Mine is rated at 80 w per ch. It sounds good, but treble is a little "wirey" compared to my more natural treble on my way cheaper 200 w per ch. jaycar amp. And the jaycar has better bass. But the NAD does sound "alive", maybe that's why they are liked so much (but just a bit more "transistory" in the treble. lol And $800 is cheap for a tube amp. who cares if it's not that powerful. The sound would be amazing, going by your reaction. I had a tube amp (an old Sansui) looked much like your old tube amp. But I had a fairly gutless tube amp as well (small size old school one) and it was less powerful but miles better in sound than the old Sansui. Your NAD started my rant. I use my NAD sometimes but usually it just sits around, but I would never sell it. Sound system nuts always need a second amp just in case one fails, and for parties elsewhere occasionally.
they also said in the description that the VU meters show tube current in real time, which i find odd because VU meter looks to show only db scale, can you tell me if your amp shows tube current or is it db scale? another concern is the shipping, and did you have to pay a customs fee which is sepperate from the shipping charge. I like the looks of the 300B tubes, right now this amp is selling for $849 on ebay but they also have the Yaqin MC-100B for the same price, i do like what i hear about the MC-100B but it does have a circuit board but it is user biased which i like.
I have presently three SE amps: Will Vincent 2A3/45, Sanei 2A3/45 and a custom-built 6BG6 tetrode. All three amps will drive my Klipsch Heresies and DCM Time Windows to adequate listening levels. Proper speaker matching is important with low-power tube amps! For my Quad 57's and Rogers LS3/5A's I prefer 20+ watts of PP power - Dynaco ST70 and Paoli/Dyna Mk3's.
Robert Jermantowicz t
The left and right imbalance could also be due to the volume pot having some tolerance. See if you can add a high value parallel resistor from center to either ends to bring that in sync with the other channel.
wow that is a review! thank you!
The white stuff as you refer to it is to show that the Joint has been inspected.in the old days it used to be a RED dye that they put on the Joint
Great review. I have the same model amp, and I agree with your description of the sound.
I like the sound of Gemtune GP-01 300B with sensitive speakers better than my hybrid tube/solid state, $1,895 Croft Phono Integrated amp, which is itself a very good integrated amp (a Stereophile Class B Recommended Component for several years).
The Croft does have better control of the bass with more impact on full range speakers, as it should with its MOSFET solid state output stages, and 45 Wpch output power.
However, for my flea watt SET amps like the Gemtune, I prefer to use an active subwoofer that has a solid state amplifier driving the subwoofer, so that the SET amp only has to drive the high efficiency speakers above the subwoofer's cross-over frequency, which in my current setup is 100 Hz. This type of setup provides the low bass control and impact of the solid state amp married to the rich upper bass and mid-range, extended sweet treble, and spacious soundstage of the SET amp. To make this work, one must be willing to spend the time and effort in listening and tweaking the subwoofer cross-over frequency, level and polarity until the transition between the subwoofer and the speakers sounds seamless.
My Gemtune amp also has a channel imbalance, which I can hear as a steering of singers and instruments off of center when they are supposed to be centered between the speakers. I corrected this using a high quality attenuator on the input of the louder channel.
Another way to handle this is to use a preamp with a balance control with this amp.
Some source components may have channel level controls, like my Oppo blu-ray player, which can be used to correct the channel imbalance. However, most of my other sources do not have channel level controls nor balance controls, hence my using an attenuator.
Would this be a good choice for Altec 755A full range drivers mounted in custom cabinets without crossovers? Thanks in advance. Great video by the way.
At one w per ch you wouldn't want a power hungry crossover. lol
Try swapping power tubes. See if that follows. If it doesn't, then you may want to check all of your electrolytic capacitors using an ESR meter. I'm thinking that is probably your problem.
@stereopolice you mentioned that this tube amp and other tube amps,dont do as well with the lows as solid state.Can you recommend a tube amp that does well through the whole frequency range?Or a hybrid that does?
wonder if you can help clear up some confusion i am getting from the Doukmall store on ebay, they have this amp forsale and one that is simular to it, i asked if the amp is auto biased or user biased and the reply that i got was just (biased) so i messaged them again and had to explain it to them in more detail, and they replied back (also self biased) so at this point im wondering how i can get the truth out of these guys, then they said it was user biased, but in the description and specs they put on the ebay site there was no mention of how its biased, so can YOU tell me if its ( self biasing or user biased) because judging by there photos i could not see any adjustment screws or ports for multimeter probes.
Why do some tube bigger? Is this something to do with output,?
You should work to Stereophile. How can you compare a PP with a SE, not to mention
the SE has OPTs (impedance matching devices). So are you listening to the 300Bs
or the transformers? Are you trying to mislead buyers? Otherwise - very good review.
How do you think this sounds compared to the DIY Tubelab SE 300b?
If you are not happy with your Fisher 500b you need to fully rebuild, upgrade and modify it. Also use the right tubes. Not cheap crap.
Were you ever able to get a schematic from Gemini Doctor/Gemtune ? I can't get a straight answer from them
No, couldn't get one. Oh well, I'm still enjoying the amp.
Great review . one of the better ,more in depth I've seen on y t . do you take requests?
Could you suggest some affordable speakers to pair with such an amplifier? Its an uncomfortable feeling when I mention decibels, spl, thd, etc and the salespeople dont know what the terms are or they reply with no one uses those terms anymore.
John Thornton John, speakers are an iffy thing; we all hear things so differently. I like full range, and use Fostex for listening. However, I'd recommend some classic Klipsch ... get on ebay and see what's for sale.
I did tons of research for tube amp/speaker matching. Since its an exclusive group that enjoys it.. speakers are hard to find manufactured unless you wanna pay good $$. DIY is the way to go. As low as $40 a pair for Atlas full range 8" with whizzer, to $2600 for a pair A series Lowthers similar size. You can buy cabinets from parts express..(love the folded horn) or be creative... that is what I did.. out ofold book shelves and cabinets from the thrift stores. ( why buy new wood/) After all those old shelves from thrift stores are REAL wood and cheap. I had fun building them but can never enjoy them. Friends, family and neighbors are always buying off from me.. ( I just cant say no..lol).
Thanks Lord for nerd tech geeks so we don't just have to trust some stranger's ears !!!...and this one can even translate all the chinese tech to street English ! Awesome video man !!
Input impedance mis match?
Hi Great review . Thank you. I am thinking to buy this as never heard 300B SET. I have David Bogen DB-212 Vintage amplifier and Klipsch Heresy I Vintage from 1982. I love the Bogen but its not SET .
Are you still use yours? One important question as like simple circuit does this amplifier has Global Negative Feedback? As I heard that Negative feedback degrades quality.
Your valued answer is much apreciated.
I suspect the imbalanced Left Right is caused by non-matching tubes.
Could well be. But, I've since added balancing pots to compensate, so no biggie. Regards ...
how do i add a balance pot ? at which point in the circuit ? cheers
Agreed, typically imbalance...can.... come from non-matching tubes. However, if this tube amp allows u to adjust the tube BIAS, then I would start there. Seems like u fixed this w balancing pots....but since u like this tube amp so much, do additional research from currents users. See what tubes they rolled to. My Yaqin MC100b allows u adjust the bias on the tubes. Honestly, I would not even think about buying a tube amp, unless it had user adjustable bias, via screwdriver and a volt meter. Tubes notoriously fade in performance over time,and also certain makes and models of tubes need bias set specifically when paired with a specific tube amp ...really only takes a few minutes every 6 months, less for more frequent daily usage..but once u roll in BETTER tubes...could be old stock vintage tubes, or newer matched tubes.....wow...u think your tube amp sounds great now...roll tubes and u reach phenomenal listening levels, especially playing vinyl, or even using a tube buffer w CDs or music streamer. High efficiency speakers are a must...if u r a basshead, can always add a subwoofer to a pair of great book shelf speakers. Have fun.
Cadê a música? Cadê o som? Porque não ligou?
Great review!
Thank you very much for this stellar review! The channel imbalance is a deciding factor for me.
Glad I could help!
The tubes are not matched to each other in pairs at the factory. Try switching them L-R then see what happens.
james borg I think he did that and got same results I would be great if a schematic were included so adjustments could be made
hi stereopolice, can you compare 1000$ hi-end speaker cable with 50$ medium class cables using your gadgets :)
It means worth to get one?
You are the FKING MAN!
specs for response above human hearing range, are useless- what matters is how good it sounds to the human ear. checking a stereo with a meter, is like sizing up a woman with a tape measure. you can get great measurements, and the package may look awesome on the surface, but you may end up with something you can't live with for more than a weekend. her "personality", tone, and habits may be horrible.same with stereos.
AWESOME comparison man, I second that ;) PS any idea weather Parallel Single Ended amplifiers sound any different than Single Ended amplifiers? this Parallel tube amp uses 2 valves per channel in paralel for more power: www.amazon.com/YAQIN-MC-550C-Vacuum-Integrated-Amplifier/dp/B00A7IZPGY
the ultimate stereo is a single ended, period. the downside is, lower volume, bass hit, power. the upside is, great detail, depth, soundstage, realism, no listening fatique. an added perk, a nice single ended stereo saves you ears from volume abuse.
How is this an integrated amp? There's no phone output.
For a 300B at this price point, it's an excellent bargain, and it sounds fantastic. Need very very efficient speakers though.
Πολύ καλός.
blows the socks off the fisher?>?> wow....
Say "soder" again.
I had to stop watching as i was getting dizzy due to the movement of the camera
If you want perfect sound go to Kipnis studio,s But you will pay for perfect sound.
channel issues a no no.
Easy way to know an electronic component is from China, all the glue they us everywhere. But, the CCP thanks you for your purchase as it helps them with their important work (keeping their people under their control).
1 watt. What? That's two, 1 w per each channel. You can't be serious. $800 for one w per ch? And no phono input?
chinese style mass goods!
Yea man. These Chinese companies make me nervous 😅
too technical its sbored
Is thou not amused? I will dance for you (spinning in circle on tip toes and right rand over head).
Great review!
Thank you!