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Posts by Chops

There's two different types of 6Z4's out there. The ones you pulled up are the American versions. The Chinese version is the one in our amps. Two totally different tube types, however they might be designed the same internally. I guess if you changed out the tube socket, it might work, but don't quote me on that. Derek would be the one to ask.
Quote: Originally Posted by dcheming Wow, quite a bit happened since I was last here. It's good to have you back Charles. Bummer about the computer virus causing so much trouble. Congrats on the new job though. I've also been making plans to put together a nice two channel system since I'll be moving to San Francisco this summer. Hopefully we'll find a place big enough to have a proper setup. Those Onix X-Statik look interesting. Open baffle...
Quote: Originally Posted by Cloth Ears Ain't that always the way...? I read somewhere on this site (before I'd become a real person and signed up) that someone wasn't sure what the voltage to the audio board should be. So I asked at the source, and received this response: Yeah, you'll have to insert a resistor in the heater curcuit to lower the voltage. Mine was 7.58v and after I installed a 1 ohm - 10 watt resistor, it dropped down to 6.63v....
Quote: Originally Posted by Cloth Ears Hi Head-fi'ers, mine is the 708B that James is modding (also my first post, over from DIYaudio & AudioKarma). I'm going along tomorrow to have a listen and discuss, so I'll take the camera and hopefully have a couple of shots to document the progress. Welcome Cloth Ears! I knew that name sounded familair. I know you from DIY Audio. Looking forward to seeing some pics and hearing what you have to say about...
Quote: Originally Posted by jrhill Yeah, following on from your work and others in this thread is like getting first hand instructions and made the upgrade quite straightforward - many thanks to you and all the others for writing up your work ... jh I'm glad to hear that we were able to help in some way. It is much easier to perform mods to something when you have good instructions and plenty of good pictures to go by. I certainly wouldn't...
Quote: Originally Posted by OblivionLord Item is still up for sale if anyone is interested. Thanks PM sent.
My brother had the LDII++. It wasn't a bad sounding amp, but boy did it ever run hotter than heck! Anyway, if you want to go on the cheap and want to roll some tubes and even try a little modding, you may want to look into the Xiang Sheng 708B. It's really not a bad little amp once you replace the stock crappy tubes for something better. And for about 30 bucks more, upgrading the volume pot and input caps will easily put this amp right up there with the higher-end amps....
Quote: Originally Posted by jrhill Hello All, This is my first post here and in the middle of modding a friends 708B and thought I'd add a bit of measured info for others to see. In Oz, we have 240v, 50Hz and this gives high volts (B+) of +215 on pcb, heaters of 7.3v ac, and the current thru the input valve (6N3, etc) is about 2.7mA, and 10.5 mA thru the 6N11s. Reducing the B+ to 195v via p/s resistors (1k2 for the 1k0 and 2k2 for the 2k0) and...
Another update... I've only had this amp back up and running for a few days now and I've already done another mod to it... Kinda. I had a couple of Solen 51uF caps sitting around that I used in a loudspeaker project a short while back. They were used to absorb any turn-on thump from an amp to a pair of compression horn drivers (as they were connected directly to the amp and were crossed over via a digital x-over). However, there was never any turn-on thump, but just...
Well I just finished uploading the 708B pictures to my site then reinserting them into this thread in all my various posts. I also reinstalled the Mundorf output caps into my amp. They really are much better sounding than the 1500uF caps I had in there. I hope to keep this thread going as it is chalk full of great information. It's simply amazing how far you can take one of these amps. A true sleeper!
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