tbonner1
Headphoneus Supremus
- Joined
- Mar 13, 2002
- Posts
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Little Dot LD2 Review
Here is the capsule review upfront so there is no need to search for the conclusion nor wade through my bloviating:
Treble 4.5 of 5 stars
Shimmering cymbals with very musical decay
Midrange 4 of 5
Lush and life like, but lacking the last bit of detail of the very best tube amps
Bass 4 of 5
Full with great impact. Not as tightly detailed and lacking the pitch and speed of the best.
Imaging 4 of 5
Great soundstage but does not have the pinpoint precision of the best solid state designs
Dynamic range 4.5 of 5
A strength of this design. If you are used to similarly priced opamp units in this price range you will be pleasantly surprised by the improvement.
BACKGROUND
I am not a newbie and have waited to write this review to be sure of my thoughts and avoid the over excitement and self-congratulations associated with a new purchase decision.
I have been frustrated with headphone and headphone amplifiers since my initial infatuation with Stax SRX and SRD-7 in 1977. I have had many satisfying speakers (Dahlquist DQ-10 to my current JM Labs Cobalt 820) and amps (Ampzilla to the current Cayin TA-30/Prima Luna tube amp), but never had headphones sound close to live music.
Recently I have found renewed interest in the Senn 580 and 650 when used with proper amplification. I went through a series of opamp based amps including several CMOY’s, Pimeta, PPA, and M3, of which the M3 was the best with the best bass. The Senn 650’s scaled well and sounded better with each improvement in amplification, which speaks very highly of the Senn’s resolving power.
An opinion often repeated with the Senn’s is that they are dark with somewhat loose bass. To offset this, many choose a solid state amp such as the Gilmore Lite, which is fast, changes the darkness of the Senn’s to light and grips the bass with nice control. I found the Gilmore (with the Elpac) clean sounding but lacking full bass and dynamic range.
BUILD QUALITY
I believe the latest generation of Chinese tube amps offers unsurpassed quality and performance at a bargain price. It is hard for anyone to compete with 35 cent an hour labor. As one example I look to my own speaker amp, the Cayin TA-30 which is very similar to the Prima Luna 2. Superb build quality and workmanship, point to point wiring, and sound that exceeds expectations at its price point. I got mine for $500 and found it compared to tube integrated amps around $2500. I would compare the Little Dot 2 to other tube headphone amps in the $300-$400 range in sound (but not build) quality.
I have no problem at all with the fit, finish and parts quality of the LD2 regardless of price, and I am particular about my audio gear. When I opened it up I found the board to be of good sturdy quality as were the tube sockets. Some inexpensive tube amps (Bada and others) don’t even have sockets and actually solder the tubes presumably to save money (Gasp! It makes you wonder what other expenses were cut). The unit has an IEC adapter to allow for power cord upgrades, and a good quality power switch. The volume pot used was not an Alps Blue level of quality, but it did not have the cheap feel of other inexpensive units. The caps and components used are of medium quality, not too low, but no audiophile name brands. If you are looking for Solen, WIMA or Black Gates look elsewhere.
The case is sturdy and made of metal. Perhaps there would be less ringing with a Bakelite or composite plastic case but the unit gets hot, and is not vented, so this is not an option. There are nice heavy-duty cardas style (not Cardas brand) RCA connectors on the rear. I think proper termination is critical for connecting the reproduction chain and this is a high point of the parts used for the LD2. They could have cut costs here.
TECHNICAL INFO
The design of the LD 2 calls for two separate drive tubes and two power tubes. Other (high-end) tube headphone amps have two driver tubes but a common power tube for both left and right stereo output. I suffered with crosstalk problems for years with even the very expensive Revox A700 reel to reel tape recorder and would prefer to minimize any crosstalk concerns with a separate tube for each channel as with the LD2.
One updated note regarding the relatively inexpensive tubes on the LD2. I have not found the 4P1S power tubes at any of the usual tube websites such as BOIAUDIOWORKS. The Little Dot distributor, David Pang, informs me that the Russian 4N1N are direct replacements for the 4P1S, although I have not tried this yet. Little Dot has upgraded the driver tubes from the 1B2 on older versions to the less microphonic 1K2. A direct replacement for the 1K2 is the 1T4. The good news is that you can order the OEM tubes from the Little Dot resellers for the comparatively bargain price total of $15 for all 4 tubes, so you may want to get a spare set when you order your amp.
SOUND
Audiophiles have known the synergy of tube preamps and high current solid state amps since the Absolute Sound touted the virtues of the tube Audio Research SP3a and Ampzilla in 1975. I like the advantage of tubes in the critical midrange and soundstage department, but with the grip and control of solid state in the bass. But even compared to the Feel HP100A 6922 tube hybrid amp, the Little Dot 2 performs quite well. The Little Dot 2 synergizes well with the Senn’s to present an open soundstage. I have heard the designer of the LD 2 likes Sennheisers. It is the lack of soundstage that has led me to dismiss countless headphone/amp combinations over the years. When compared to speakers, headphone sound simply did not come close to the image presented by stereo speakers.
Tubes seem to have a distinct advantage over opamps in this difficult area. Many argue that this is a euphoric coloration that adds an element of distortion. This may be true, but the result with tubes sounds more like live music to me.
With the new generation of Chinese tube headphone amps, I can now experiment with different amps such as the Ming Da 66 without breaking the bank. The Feel HP100A reminds me of the Stereophile recommended Melos SHA headphone amp which also uses the 6922 tubes although I do not have both on hand to compare.
I find myself largely in compliance with pjr300’s detailed review:
http://www4.head-fi.org/forums/showthread.php?t=146825
The Little Dot 2 sounds a bit more coherent across the frequency spectrum than the hybrid 6922 tube/mosfet amp. Treble is tilted up a bit which adds “light” to the Senns. The decay on cymbals is typical tube, which allows for proper sheen. If you are used to hearing truncated solid state note decay on cymbals on other treble sounds you will be surprised at all the analog sounding detail in your digital recordings through tubes. Midrange is lush and tube smooth (without losing too much detail) and has a wide soundstage. That soundstage is not as pinpoint as the opamp, solid state and mosfet amps but it is so open and musical it detracts very little from the listening experience. The bass is where the real surprise is: It is powerful and full unlike many of the opamp based headphone amps. The bass does not have the detail and pitch definition of other solid state amps, but it is close. The LD2 also has good bass impact and slam lacking on many opamp based amplifiers.
A negative of the LD2 is that it sounds congested during complex music passages when the amp is strained. I believe this may be, at least partly, due to a less than robust power supply. In my experience, there is no substitute for a big, beefy filtered power supply. This is one of the most expensive parts of an amplifier and you usually have to pay to have this done right. The WooAudio3 is better built and uses the good sounding and easy to find 6922 tubes. Little Dot has an upgraded LD3 plus with an isolated power supply with better parts, which I believe is the designer, Mr. Yang’s attempt to address this issue.
I have read comments about the (high) noise floor of the LD2. I find the unit to be quiet compared with other tube amps with hardly a trace of hum with the Senn 650. You may need to take some care to keep the LD2 away from other power supplies or from stacking for the best performance depending on the shielding you have, or don’t have, on your other equipment. You can also purchase relatively (compared to 5-10 years ago) inexpensive power filters from companies like Monster that may help lower the noise. Despite the low cost tubes used, with the exception of microphonics (which can be ameliorated with tube dampers and isolation feet) I found very few typical tube artifacts with the LD2.
CUSTOMER SERVICE
My experience with the Little Dot representative, David Pang who sells on Ebay, was very positive. I have found not only a language barrier dealing with many other Chinese vendors, but cultural barriers as well. The combination has resulted in what translates into the appearance of cryptic and/or rude emails. This can make pre and post sales support unsettling to audiophiles if you are used to good customer service from superb companies such as Ultimate Ears (who have migrated from a pro audio customer base). Post sales service and support can be non-existent (i.e. you bought it, you own the problem and with no US service centers). David responded almost instantly to emails in detail and with precise technical information. After the sale he responded to a shipment problem and corrected it right away. He has been very helpful for after sale support as well. The Little Dot arrived to my door in great shape with custom foam packing 4 days after my order from China with tracking.
The new version of the Little Dot 2 is version 4. Although they have not updated the model designation, this shows an ongoing attempt by a small manufacturer to improve a good simple design after the early cap improvements. If you have the unit with the 1K2 tubes you have the latest revision as of the day of this review. The newer revision can also be determined by finding a labeled jumper on the circuit board that allows you to use either the 1B2 or newer 1K2 tube.
OTHER HEADFI LD2 OWNER COMMENTS
From another LD2 owner and headfi member who has owned a PPX and WooAudio3. I asked him to comment regarding the bass difference between these three tube amps:
Wow! That's quite a nice, in depth review. I'd say you're pretty spot on with what you said. A couple of things that could be better:
Tube sockets seem low-moderate in quality
Potentiometer could use a step up
Knob is cheap in feel and materials
Paint on transformer box flakes easily
Everything else, like the board quality and materials inside seem to be of decent quality.
Perhaps the maker has changed the formula since he built mine. The LDII I got was one of the first ones built, back before there was much of an interest from overseas buyers. The sound is definitely one of the warmest amps I've heard. I listen with HD650s and other various portable headphones before I go to sleep, like porta pros. I have heard the LDII has been voiced for Sennheisers. I'm surprised the new LDII has more upfront treble, it might be worth picking up a second one just to hear the differences.
Bass on all the amps is decent, nothing as good as solid state, but decent. If I had to assign a number I guess this would be about right:
tweaked Woo3-7
PPX3 6SN7-6
LDII-5
End of other headfi member comments
My response:
I agree that the volume pot could benefit from an improvement. The knob is not the best but it is metal and has grooves for improved grip. If you get one of the metallic paints you will improve your chances against flaking.
The original LD2 has been replaced and updated (4 revisions to date) and the sound has changed. I did not find my unit tended to be warm.
CONCLUSION
As of 6/16/06 the new Little Dot 2 is being sold for $95 plus shipping on Ebay. The price of this amplifier is less than the price of replacement tubes for some other headphone amps resulting in the decision to try one being a no-brainer. Despite the low price, I consider the LD2 to have an audiophile level of sound in a modern headphone amp. The (low) price and (high) performance of the LD2 must be a nightmare for other headphone amp manufacturers in the $200-$300 range. The Millet hybrid has been around for some time as another low priced tube amp. But it is not a pure tube amp and costs around $250. The Xiang Sheng 708B sells for around $190. It has slightly better build quality and perhaps a bit better power supply. The 708B has some positive comments and I have one that I would like to review. I find it great fun to get 80-90% of the performance of high-end headphone amps for around one-third of the price with the LD2. If someone can tell me of a better deal for any home headphone amplifier I would like to hear about it.
Here is the capsule review upfront so there is no need to search for the conclusion nor wade through my bloviating:
Treble 4.5 of 5 stars
Shimmering cymbals with very musical decay
Midrange 4 of 5
Lush and life like, but lacking the last bit of detail of the very best tube amps
Bass 4 of 5
Full with great impact. Not as tightly detailed and lacking the pitch and speed of the best.
Imaging 4 of 5
Great soundstage but does not have the pinpoint precision of the best solid state designs
Dynamic range 4.5 of 5
A strength of this design. If you are used to similarly priced opamp units in this price range you will be pleasantly surprised by the improvement.
BACKGROUND
I am not a newbie and have waited to write this review to be sure of my thoughts and avoid the over excitement and self-congratulations associated with a new purchase decision.
I have been frustrated with headphone and headphone amplifiers since my initial infatuation with Stax SRX and SRD-7 in 1977. I have had many satisfying speakers (Dahlquist DQ-10 to my current JM Labs Cobalt 820) and amps (Ampzilla to the current Cayin TA-30/Prima Luna tube amp), but never had headphones sound close to live music.
Recently I have found renewed interest in the Senn 580 and 650 when used with proper amplification. I went through a series of opamp based amps including several CMOY’s, Pimeta, PPA, and M3, of which the M3 was the best with the best bass. The Senn 650’s scaled well and sounded better with each improvement in amplification, which speaks very highly of the Senn’s resolving power.
An opinion often repeated with the Senn’s is that they are dark with somewhat loose bass. To offset this, many choose a solid state amp such as the Gilmore Lite, which is fast, changes the darkness of the Senn’s to light and grips the bass with nice control. I found the Gilmore (with the Elpac) clean sounding but lacking full bass and dynamic range.
BUILD QUALITY
I believe the latest generation of Chinese tube amps offers unsurpassed quality and performance at a bargain price. It is hard for anyone to compete with 35 cent an hour labor. As one example I look to my own speaker amp, the Cayin TA-30 which is very similar to the Prima Luna 2. Superb build quality and workmanship, point to point wiring, and sound that exceeds expectations at its price point. I got mine for $500 and found it compared to tube integrated amps around $2500. I would compare the Little Dot 2 to other tube headphone amps in the $300-$400 range in sound (but not build) quality.
I have no problem at all with the fit, finish and parts quality of the LD2 regardless of price, and I am particular about my audio gear. When I opened it up I found the board to be of good sturdy quality as were the tube sockets. Some inexpensive tube amps (Bada and others) don’t even have sockets and actually solder the tubes presumably to save money (Gasp! It makes you wonder what other expenses were cut). The unit has an IEC adapter to allow for power cord upgrades, and a good quality power switch. The volume pot used was not an Alps Blue level of quality, but it did not have the cheap feel of other inexpensive units. The caps and components used are of medium quality, not too low, but no audiophile name brands. If you are looking for Solen, WIMA or Black Gates look elsewhere.
The case is sturdy and made of metal. Perhaps there would be less ringing with a Bakelite or composite plastic case but the unit gets hot, and is not vented, so this is not an option. There are nice heavy-duty cardas style (not Cardas brand) RCA connectors on the rear. I think proper termination is critical for connecting the reproduction chain and this is a high point of the parts used for the LD2. They could have cut costs here.
TECHNICAL INFO
The design of the LD 2 calls for two separate drive tubes and two power tubes. Other (high-end) tube headphone amps have two driver tubes but a common power tube for both left and right stereo output. I suffered with crosstalk problems for years with even the very expensive Revox A700 reel to reel tape recorder and would prefer to minimize any crosstalk concerns with a separate tube for each channel as with the LD2.
One updated note regarding the relatively inexpensive tubes on the LD2. I have not found the 4P1S power tubes at any of the usual tube websites such as BOIAUDIOWORKS. The Little Dot distributor, David Pang, informs me that the Russian 4N1N are direct replacements for the 4P1S, although I have not tried this yet. Little Dot has upgraded the driver tubes from the 1B2 on older versions to the less microphonic 1K2. A direct replacement for the 1K2 is the 1T4. The good news is that you can order the OEM tubes from the Little Dot resellers for the comparatively bargain price total of $15 for all 4 tubes, so you may want to get a spare set when you order your amp.
SOUND
Audiophiles have known the synergy of tube preamps and high current solid state amps since the Absolute Sound touted the virtues of the tube Audio Research SP3a and Ampzilla in 1975. I like the advantage of tubes in the critical midrange and soundstage department, but with the grip and control of solid state in the bass. But even compared to the Feel HP100A 6922 tube hybrid amp, the Little Dot 2 performs quite well. The Little Dot 2 synergizes well with the Senn’s to present an open soundstage. I have heard the designer of the LD 2 likes Sennheisers. It is the lack of soundstage that has led me to dismiss countless headphone/amp combinations over the years. When compared to speakers, headphone sound simply did not come close to the image presented by stereo speakers.
Tubes seem to have a distinct advantage over opamps in this difficult area. Many argue that this is a euphoric coloration that adds an element of distortion. This may be true, but the result with tubes sounds more like live music to me.
With the new generation of Chinese tube headphone amps, I can now experiment with different amps such as the Ming Da 66 without breaking the bank. The Feel HP100A reminds me of the Stereophile recommended Melos SHA headphone amp which also uses the 6922 tubes although I do not have both on hand to compare.
I find myself largely in compliance with pjr300’s detailed review:
http://www4.head-fi.org/forums/showthread.php?t=146825
The Little Dot 2 sounds a bit more coherent across the frequency spectrum than the hybrid 6922 tube/mosfet amp. Treble is tilted up a bit which adds “light” to the Senns. The decay on cymbals is typical tube, which allows for proper sheen. If you are used to hearing truncated solid state note decay on cymbals on other treble sounds you will be surprised at all the analog sounding detail in your digital recordings through tubes. Midrange is lush and tube smooth (without losing too much detail) and has a wide soundstage. That soundstage is not as pinpoint as the opamp, solid state and mosfet amps but it is so open and musical it detracts very little from the listening experience. The bass is where the real surprise is: It is powerful and full unlike many of the opamp based headphone amps. The bass does not have the detail and pitch definition of other solid state amps, but it is close. The LD2 also has good bass impact and slam lacking on many opamp based amplifiers.
A negative of the LD2 is that it sounds congested during complex music passages when the amp is strained. I believe this may be, at least partly, due to a less than robust power supply. In my experience, there is no substitute for a big, beefy filtered power supply. This is one of the most expensive parts of an amplifier and you usually have to pay to have this done right. The WooAudio3 is better built and uses the good sounding and easy to find 6922 tubes. Little Dot has an upgraded LD3 plus with an isolated power supply with better parts, which I believe is the designer, Mr. Yang’s attempt to address this issue.
I have read comments about the (high) noise floor of the LD2. I find the unit to be quiet compared with other tube amps with hardly a trace of hum with the Senn 650. You may need to take some care to keep the LD2 away from other power supplies or from stacking for the best performance depending on the shielding you have, or don’t have, on your other equipment. You can also purchase relatively (compared to 5-10 years ago) inexpensive power filters from companies like Monster that may help lower the noise. Despite the low cost tubes used, with the exception of microphonics (which can be ameliorated with tube dampers and isolation feet) I found very few typical tube artifacts with the LD2.
CUSTOMER SERVICE
My experience with the Little Dot representative, David Pang who sells on Ebay, was very positive. I have found not only a language barrier dealing with many other Chinese vendors, but cultural barriers as well. The combination has resulted in what translates into the appearance of cryptic and/or rude emails. This can make pre and post sales support unsettling to audiophiles if you are used to good customer service from superb companies such as Ultimate Ears (who have migrated from a pro audio customer base). Post sales service and support can be non-existent (i.e. you bought it, you own the problem and with no US service centers). David responded almost instantly to emails in detail and with precise technical information. After the sale he responded to a shipment problem and corrected it right away. He has been very helpful for after sale support as well. The Little Dot arrived to my door in great shape with custom foam packing 4 days after my order from China with tracking.
The new version of the Little Dot 2 is version 4. Although they have not updated the model designation, this shows an ongoing attempt by a small manufacturer to improve a good simple design after the early cap improvements. If you have the unit with the 1K2 tubes you have the latest revision as of the day of this review. The newer revision can also be determined by finding a labeled jumper on the circuit board that allows you to use either the 1B2 or newer 1K2 tube.
OTHER HEADFI LD2 OWNER COMMENTS
From another LD2 owner and headfi member who has owned a PPX and WooAudio3. I asked him to comment regarding the bass difference between these three tube amps:
Wow! That's quite a nice, in depth review. I'd say you're pretty spot on with what you said. A couple of things that could be better:
Tube sockets seem low-moderate in quality
Potentiometer could use a step up
Knob is cheap in feel and materials
Paint on transformer box flakes easily
Everything else, like the board quality and materials inside seem to be of decent quality.
Perhaps the maker has changed the formula since he built mine. The LDII I got was one of the first ones built, back before there was much of an interest from overseas buyers. The sound is definitely one of the warmest amps I've heard. I listen with HD650s and other various portable headphones before I go to sleep, like porta pros. I have heard the LDII has been voiced for Sennheisers. I'm surprised the new LDII has more upfront treble, it might be worth picking up a second one just to hear the differences.
Bass on all the amps is decent, nothing as good as solid state, but decent. If I had to assign a number I guess this would be about right:
tweaked Woo3-7
PPX3 6SN7-6
LDII-5
End of other headfi member comments
My response:
I agree that the volume pot could benefit from an improvement. The knob is not the best but it is metal and has grooves for improved grip. If you get one of the metallic paints you will improve your chances against flaking.
The original LD2 has been replaced and updated (4 revisions to date) and the sound has changed. I did not find my unit tended to be warm.
CONCLUSION
As of 6/16/06 the new Little Dot 2 is being sold for $95 plus shipping on Ebay. The price of this amplifier is less than the price of replacement tubes for some other headphone amps resulting in the decision to try one being a no-brainer. Despite the low price, I consider the LD2 to have an audiophile level of sound in a modern headphone amp. The (low) price and (high) performance of the LD2 must be a nightmare for other headphone amp manufacturers in the $200-$300 range. The Millet hybrid has been around for some time as another low priced tube amp. But it is not a pure tube amp and costs around $250. The Xiang Sheng 708B sells for around $190. It has slightly better build quality and perhaps a bit better power supply. The 708B has some positive comments and I have one that I would like to review. I find it great fun to get 80-90% of the performance of high-end headphone amps for around one-third of the price with the LD2. If someone can tell me of a better deal for any home headphone amplifier I would like to hear about it.
