mopardave Posted January 12, 2019 Author Share Posted January 12, 2019 22 minutes ago, Ossidian said: True, if you are bypassing the preamp section of your integrated the Mapletree preamp tubes would be best to concentrate on. Without seeing the schematics on the Ap-900 I have no idea what role the 6N1P play in the integrated. I have searched the internet but found no information on the AP-900. Don't know if this helps. Craig at nosvalves did some modds way back with the large green caps and small yellow caps. Also the resistors on pins 8. Quote Link to comment Share on other sites More sharing options...
mopardave Posted January 12, 2019 Author Share Posted January 12, 2019 I just changed out the sovtek 12ax7LF for the original Chinese 12ax7 and the sound is more detailed in the highs with a brighter clearer sound. Quote Link to comment Share on other sites More sharing options...
Ossidian Posted January 12, 2019 Share Posted January 12, 2019 1 hour ago, mopardave said: I just changed out the sovtek 12ax7LF for the original Chinese 12ax7 and the sound is more detailed in the highs with a brighter clearer sound. Looks like the tech installed some nice Russian and Hovland caps in your AP-900. It's amazing how swapping tubes affect the sonics. The AP-900 is quite a nice unit indeed. Quote Link to comment Share on other sites More sharing options...
mopardave Posted January 12, 2019 Author Share Posted January 12, 2019 14 hours ago, Ossidian said: Looks like the tech installed some nice Russian and Hovland caps in your AP-900. It's amazing how swapping tubes affect the sonics. The AP-900 is quite a nice unit indeed. Yes, I will play with it some more today. Yeah, Craig@nosvalves does nice work. Inventor/builder of the VRD's I think there called. Work was done in 2003 when I bought the amp. Wish I new what the 6n1's where actually doing. I found an old post by nosvalves about the Mapletree pre. He said at that time the 12sx7GT was much better than the 12sn7GT that I currently using/came with. I found some old stock tested 90% or better smoked glass 12sx7GT last night on ebay and bought them. Curious to see what these do as well. Thanks Quote Link to comment Share on other sites More sharing options...
mopardave Posted January 12, 2019 Author Share Posted January 12, 2019 10 hours ago, Ossidian said: Looks like the tech installed some nice Russian and Hovland caps in your AP-900. It's amazing how swapping tubes affect the sonics. The AP-900 is quite a nice unit indeed. I'm looking for an inexpensive, low watt kt88 tube amp to play with(Douk). I have my heart set on this amp, just haven't pulled the trigger yet. What's your opinion? Curious to know what low watt(13w) and kt88 sound like. 1 Quote Link to comment Share on other sites More sharing options...
thebes Posted January 12, 2019 Share Posted January 12, 2019 Did you let the amp warm up for an hour or so before setting the bias. It's my understanding the tubes stabilize after a bit and then setting the bias results on a more accurate setting. Quote Link to comment Share on other sites More sharing options...
mopardave Posted January 12, 2019 Author Share Posted January 12, 2019 45 minutes ago, thebes said: Did you let the amp warm up for an hour or so before setting the bias. It's my understanding the tubes stabilize after a bit and then setting the bias results on a more accurate setting. yes, biasing right now. amps been on all day. thanks Quote Link to comment Share on other sites More sharing options...
codewritinfool Posted January 12, 2019 Share Posted January 12, 2019 I'm looking for an inexpensive, low watt kt88 tube amp to play with(Douk). I have my heart set on this amp, just haven't pulled the trigger yet. What's your opinion? Curious to know what low watt(13w) and kt88 sound like. That’s a beauty. Which model is that? Quote Link to comment Share on other sites More sharing options...
codewritinfool Posted January 12, 2019 Share Posted January 12, 2019 Nevermind, found it. It is $549 on Amazon and $509 direct from doukaudio. Sweet amp! Quote Link to comment Share on other sites More sharing options...
mopardave Posted January 12, 2019 Author Share Posted January 12, 2019 39 minutes ago, codewritinfool said: Nevermind, found it. It is $549 on Amazon and $509 direct from doukaudio. Sweet amp! Sorry, was working on my Maple tree pre amp. That little amp is $497 on ebay/free shipping from Douk. I may get this ordered before the price goes back up. 1 Quote Link to comment Share on other sites More sharing options...
codewritinfool Posted January 16, 2019 Share Posted January 16, 2019 Be careful. I was excited about this inexpensive amp and told @Hornographic about it, and he pointed me to an online forum warning about potential fakes. Not this model, but apparently someone ordered a tube amp from China, took it apart, and discovered that the output transformer was hollow. Inside was a small solid-state amp board and associated regulators. There was a filament supply to light the tubes up, but no high-voltage supply anywhere. The audio path was wired in some way to use the tubes as path components. The tubes did nothing, other than when you removed a tube, the audio stopped for that channel. I'm now curious to see if anyone has disassembled one of these enough to see the socket wiring, check for high voltage, etc. Mind you, it was not this model (I don't think so, anyway), but if this is true it isn't cool. Edit: One of the sites talking about it is here: http://audiokarma.org/forums/index.php?threads/nobsound-fake-hybrid-tube-amp.706645/ Quote Link to comment Share on other sites More sharing options...
mopardave Posted January 16, 2019 Author Share Posted January 16, 2019 26 minutes ago, codewritinfool said: Be careful. I was excited about this inexpensive amp and told @Hornographic about it, and he pointed me to an online forum warning about potential fakes. Not this model, but apparently someone ordered a tube amp from China, took it apart, and discovered that the output transformer was hollow. Inside was a small solid-state amp board and associated regulators. There was a filament supply to light the tubes up, but no high-voltage supply anywhere. The audio path was wired in some way to use the tubes as path components. The tubes did nothing, other than when you removed a tube, the audio stopped for that channel. I'm now curious to see if anyone has disassembled one of these enough to see the socket wiring, check for high voltage, etc. Mind you, it was not this model (I don't think so, anyway), but if this is true it isn't cool. Edit: One of the sites talking about it is here: http://audiokarma.org/forums/index.php?threads/nobsound-fake-hybrid-tube-amp.706645/ Yes. I read about that the other day. Not cool. I bought this from doukmall. 1yr warranty I think. Can't wait to get it to look it over. Thanks Quote Link to comment Share on other sites More sharing options...
codewritinfool Posted January 16, 2019 Share Posted January 16, 2019 16 hours ago, mopardave said: Yes. I read about that the other day. Not cool. I bought this from doukmall. 1yr warranty I think. Can't wait to get it to look it over. Thanks Dave, The thing I'd check for is the presence of microphonics. Lightly flicking a tube with your finger may produce an audible result in the output if the tube is really doing something. I'm hoping that someone with a ton more experience will comment on this. Quote Link to comment Share on other sites More sharing options...
mopardave Posted January 16, 2019 Author Share Posted January 16, 2019 32 minutes ago, codewritinfool said: Dave, The thing I'd check for is the presence of microphonics. Lightly flicking a tube with your finger may produce an audible result in the output if the tube is really doing something. I'm hoping that someone with a ton more experience will comment on this. Ok I'll try that. Quote Link to comment Share on other sites More sharing options...
mopardave Posted February 3, 2019 Author Share Posted February 3, 2019 Ok, the Gold Lion KT77 came around real nicely. Sounds very good and easy to listen to. I rolled the KT77 JJ's back in this weekend and listed for half a day. Awesome tube as well. Horns, strings and vocals just a bit more revealing. The GL smoother and easy to listen to all day and the JJ closer to real, but the bass was deeper and a little flabby I thought. They both have their merits and I like them both. Quote Link to comment Share on other sites More sharing options...
Mopardamo Posted February 3, 2019 Share Posted February 3, 2019 I know nearly nothing about tub gear. Just thought it would be cool to have mopardave & mopardamo in the same thread.LOL Glad you like the sound of both! Quote Link to comment Share on other sites More sharing options...
mopardave Posted February 3, 2019 Author Share Posted February 3, 2019 39 minutes ago, Mopardamo said: I know nearly nothing about tub gear. Just thought it would be cool to have mopardave & mopardamo in the same thread.LOL Glad you like the sound of both! Cool! another mopar guy. I don't know anything about tubes either, just playin and enjoyin. Good winter hobby. 1 Quote Link to comment Share on other sites More sharing options...
Les Lammers Posted February 5, 2019 Share Posted February 5, 2019 On 1/8/2019 at 8:12 AM, mopardave said: New Genalex kt77 in my amp. How much burn in time is required? Regarding the GLKT77 from Upscale Audio: A quick note on this tube: These tubes seem to take a bit longer to break in than some other power tubes, so if they sound a little lightweight in the bass, you have to give them time. Some guys are reporting at least 100 hours before the fully come into their own. Quote Link to comment Share on other sites More sharing options...
mopardave Posted February 5, 2019 Author Share Posted February 5, 2019 48 minutes ago, Les Lammers said: Regarding the GLKT77 from Upscale Audio: A quick note on this tube: These tubes seem to take a bit longer to break in than some other power tubes, so if they sound a little lightweight in the bass, you have to give them time. Some guys are reporting at least 100 hours before the fully come into their own. That's good to know. Bass could be a bit better in the mids, but very happy with these. Quote Link to comment Share on other sites More sharing options...
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