Dhillon Posted May 21, 2016 Share Posted May 21, 2016 (edited) Would like to start a mini thread here instead of hijacking the 'Show us your tubes post', together posting with some better photos: http://www.stereo.net.au/forums/index.php/topic/51808-show-us-your-tubes/page-18#entry1625921 Firstly as all reviews, it's subjective, so if you don't agree please don't be upset Introducing is the latest invention from Eric Chan, aka McChanson. For a lots of people in the forum the name is not new. He's a local master amp builder in Sydney. Here introducing is the latest product from him, a 3 tubes SET amp using 2 6EM7 and 1 rectifier. According to Eric this's his second made of this kind and was never on public listing. Spec: 2W Single End Triode (SET) Class-A (of course) Rectifier: (one) Could use any in-direct heated GZ30 / 32 / 34 Driver / Power: (two) 6EM7 Size: 10.5 x 14.5 inch (Junior Chassis in Eric's term) Functions: okay @@liteneasy you spotted it. This amp is 3-in-1. Speaker out / Line out (as pre-amp) / Headphone amp As a Integrated amp It produces a rich and warm tube sounds. Similar to other McChanson amp I have (6AS7) I found that it's very sensitive to tube rolling and cable matching. As it's 2W only I would recommend you to borrow one from Eric to try in your setup and see if it's sufficient for you before you buy. (I did). I am using it in my bedroom for music before sleep so much more than enough power, normally turning volume to around 8 o'clock only with an old pair of Marantz speakers. Impression on this 2W amp is it got a very quiet noise floor, probably because of its 'direct coupling' design. (we'll talk more on the design section). If you also have a few pairs of 6EM7 / some GZ's from your Woo or any other headphone amp I would highly recommend you to give this a try and reuse your existing GZ's together. One example is the Mullard 6EM7 as a pure driver I found that create a bit of noise. When using on this amp as driver + power direct coupling it's perfectly right and sounds much more open / airy sound. If you don't have any existing, Eric still go some good NOS GE 6EM7 on sales and that's the pair I am using lately. (if plp are interested I may post some reviews on the 6EM7 I used). Personally saying I think tube rolling is really fun!! Specially on a tube amp that needing only 3 or 4 tubes you can do that whatever you feel like pretty much. I got a friend with a mcint 275 forgotten to turn off overnight and burnt one power tube ending up replacing all 4 (or 8? can't remember) to match. Not the case here, the most damage you can do is one tube (do both driver and power, more in the design section). Bias adjustment? non-existing / not needed. Just buy more / try more tubes and the combinations into the amp and you're be surprised how good the amp provide you as a platform for tube rolling and music enjoyment tailored to your taste. As a Line out (preamp) Be honest I haven't try it so can't comment. I may try later and update this post. According to the first owner of this kind it's the best usage out of all the 3 features. Myself do not have a good power amp to try it out (maybe someone in Sydney like to try I can come with it for an audition session?) As a headphone amp I am using this to drive my Beyer DT-880 250 ohm and is more than enough (I turn to around 11 o'clock). But keeping in mind DT-880 is not that hard to drive anyway. Sound is good and rich. Same sound signature as whatever tubes you throw in to the amp on speaker out. DT-880 itself is more a nature / open can that benefit from the tube warm sound. So think of connecting a very good monitor speaker to the amp output is what the headphone jack can provide with my DT-880. Depends on your placement, I do need to unplug all cables and move the amp around in the house to use as a headphone amp. The amp itself is the 'Junior' and not the 'Mini' chassis in Eric's terms so is slightly bigger. Still 'portable' in the sense of moving around in house, obviously it's not any true portable headphone amp to say. And the main reason of using this Junior chassis instead of Mini is that I wanted to use a GZ32 instead of a small rectifier. You can order the same 6EM7 amp from Eric using smaller size rectifier on a Mini chassis if this concerns you. Design: Now come to the design - firstly please forgive me if I used any incorrect terms etc as I'm not any expert in any tube / amp building. It is by design a pure Single End Triode amplifier. So obviously it's also a class-A design as it's Single End and nothing to do any push-pull. As a three tubes amp, it's using one rectifier and two 6EM7 tubes. Since the 6EM7 tube itself is indirect heated and there's no separated slow start circuit, recommendation is to use a indirect heated rectifier to avoid directly powering up the 6EM7. This particular design (on my request) accepts a larger output rectifier and can use any of GZ30, GZ32 and GZ34 or equivalent (like 5Z4, 5ar4 etc). Usage of rectifier is up to your personal taste and some people / amp builder prefer not to. I personally found a good rectifier contributing to a much solid bass and open sound-stage so I do enjoy using it. The standard rectifier comes with Eric's amp is also good as well. Comes to the 6EM7 is a bit of story and learning for myself. So how's the single tube power up one channel and therefore needing only 2 tubes for 2 channels? The answer is a dual-triode. Normally in a valve you'll see 8-pins, our modern valve designs (KT-88 eg) are using as a pentode for higher power output and you can only fit one set of pentode into 1 set of 8 pins. In the case of triode, since you got 8 pins it's possible and common in the old day design to fit 2 sets of triodes into a set of 8 pins, therefore you got 2 triodes in one tube!! How is that being used? Then come to the basic of tube design you always need a driver and a power tube for a good stable output. On this Eric's creation, he use one set of triode as a driver and the other set of triode wiring as output all in the single dual triode tube. As a result, since you can only using one tube or not using it and they started / stopped at the same time, there's no need of an extra capacitor in between to safeguard / separate the two and therefore is 'direct coupled'. SET circuit is famous on it's simple design and removing the need on the capacitor further pushing that envelope. Is that sounds better? that's another subjective question but at least it saves you the costs on expensive capacitor upgrades - save your money and invest on NOS tubes! Conclusion: Another beautiful creation from Eric Chan!! If you are new to tube amp or using similar tubes on headphone amps and would like to explore into speakers I would highly recommend to give this a try. Typical Eric sound signature - warm and open sound Sensitive to tube rolling and is inexpensive on this 3 tubes amp design, and fun!! Multi-function, can be used as an integrated, preamp or headphone amp (Contact Eric for a price) won't break your bank account, with local support My first review post. Thanks for viewing. Edited May 21, 2016 by Dhillon 9 1 Link to comment Share on other sites More sharing options...
dwbasement Posted May 21, 2016 Share Posted May 21, 2016 (edited) Nice review there Nicky, I've heard most of Eric's amps, I must say his Sv83 is his best miniwatt amps so far. I thought I have tried the 6em7 before but apparently it might have been a 6FD7 and or a 6BQ5 Anyway, all Eric's amps are super good value, and depends on what your taste and setup, you can always find one that suits. Sent from my C6903 using Tapatalk Edited May 22, 2016 by dwbasement Link to comment Share on other sites More sharing options...
Happy Posted May 22, 2016 Share Posted May 22, 2016 I have a trio of his 6fd7 amps.. Sent from my iPad using Tapatalk 1 Link to comment Share on other sites More sharing options...
alucart1985 Posted June 20, 2016 Share Posted June 20, 2016 I have his 300b amplifier, modified with a headphone output - sings beautifully! 1 Link to comment Share on other sites More sharing options...
Krispy Audio Posted June 20, 2016 Share Posted June 20, 2016 I've heard one of his amps at a customers house and was really impressed not only at the sound, but the low pricing too! 1 Link to comment Share on other sites More sharing options...
Happy Posted June 20, 2016 Share Posted June 20, 2016 I've heard one of his amps at a customers house and was really impressed not only at the sound, but the low pricing too! Sure is! His amps price solved my having to feed SET to my horns in a multi active amping way Sent from my iPad using Tapatalk Link to comment Share on other sites More sharing options...
Dhillon Posted June 20, 2016 Author Share Posted June 20, 2016 Sure is! His amps price solved my having to feed SET to my horns in a multi active amping way Sent from my iPad using Tapatalk @@davidro so you're using 3 amps to drive your stereo speakers? Interested to know your setup Link to comment Share on other sites More sharing options...
Happy Posted June 20, 2016 Share Posted June 20, 2016 @@davidro so you're using 3 amps to drive your stereo speakers? Interested to know your setup 4 amps. There's a 440wpc carrying out the bass bin duties! Sent from my iPad using Tapatalk Link to comment Share on other sites More sharing options...
dwbasement Posted June 29, 2016 Share Posted June 29, 2016 @@davidro so you're using 3 amps to drive your stereo speakers? Interested to know your setup@@davidro lives in a concert hall!Sent from my C6903 using Tapatalk 1 Link to comment Share on other sites More sharing options...
Happy Posted June 29, 2016 Share Posted June 29, 2016 @@davidro lives in a concert hall! Sent from my C6903 using Tapatalk he's been to the hall now too.... Link to comment Share on other sites More sharing options...
dwbasement Posted June 29, 2016 Share Posted June 29, 2016 he's been to the hall now too....Yep, was lucky to get a premium ticket.Sent from my C6903 using Tapatalk Link to comment Share on other sites More sharing options...
Happy Posted June 29, 2016 Share Posted June 29, 2016 Yep, was lucky to get a premium ticket. Sent from my C6903 using Tapatalk i mean the OP you should come around again too man. the hall has upgraded. Link to comment Share on other sites More sharing options...
dwbasement Posted June 29, 2016 Share Posted June 29, 2016 i mean the OP you should come around again too man. the hall has upgraded. Oh yes, he picked up the cd and something...can't remember. I will definitely come again when I am not as busy... Sent from my C6903 using Tapatalk 1 Link to comment Share on other sites More sharing options...
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