Hi,
I saw this preamp offered from Philly Audio and was wondering if anyone can give me their thoughts about their design. The literature states the following:
7B is a real build quality preamp, with harmonious blend of high musicality and transparency. Sound quality can be better than that of preamps priced five times more. 6N3 are very good vintage tubes, sweet and musical. The 6N3 replacement - WE396A/2C51 - can be found from Western Electric; GE JAN 5760 can also be a substitute of 6N3. They work even in mixed combinations (for example, two WE396A tubes in the front + two JAN 5760 or 6N3 tubes at the back). It's a game you can play.
7B uses 2 6N3 dual triode tubes per channel. One channel uses one dual triode to acquire two-stage gain; the signal couples to the other triode 6N3, based on a SRPP design pattern. 7B takes advantage of 120 Watts power transformer to make more stable and smooth power supply. B+ power supply design uses 5Z4 to do the full-range rectification and employs CLC filter circuit. You can see the big choke from the photo. Choke and cap filter has much more smooth and steady output than solid-state does. All capacitors (except one) are specially made MKP film ones.
http://www.phillyaudio.com/id26.html
Thanks in advance
I saw this preamp offered from Philly Audio and was wondering if anyone can give me their thoughts about their design. The literature states the following:
7B is a real build quality preamp, with harmonious blend of high musicality and transparency. Sound quality can be better than that of preamps priced five times more. 6N3 are very good vintage tubes, sweet and musical. The 6N3 replacement - WE396A/2C51 - can be found from Western Electric; GE JAN 5760 can also be a substitute of 6N3. They work even in mixed combinations (for example, two WE396A tubes in the front + two JAN 5760 or 6N3 tubes at the back). It's a game you can play.
7B uses 2 6N3 dual triode tubes per channel. One channel uses one dual triode to acquire two-stage gain; the signal couples to the other triode 6N3, based on a SRPP design pattern. 7B takes advantage of 120 Watts power transformer to make more stable and smooth power supply. B+ power supply design uses 5Z4 to do the full-range rectification and employs CLC filter circuit. You can see the big choke from the photo. Choke and cap filter has much more smooth and steady output than solid-state does. All capacitors (except one) are specially made MKP film ones.
http://www.phillyaudio.com/id26.html
Thanks in advance
hey that's interesting!
i have a couple of western electric 407A, 407B, RCA 407A, Ratheon 2C51, western electric 396A and 5670 (given to me by a friend who has around 300 of this tube!)
i experimented on one using the topology i can understand- cathode follower.
it sounds good to me, that it replaced the Foreplay i've been using for years.
but i'm still interested on what else can be done using these tubes!
i have a couple of western electric 407A, 407B, RCA 407A, Ratheon 2C51, western electric 396A and 5670 (given to me by a friend who has around 300 of this tube!)
i experimented on one using the topology i can understand- cathode follower.
it sounds good to me, that it replaced the Foreplay i've been using for years.
but i'm still interested on what else can be done using these tubes!
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A fat 6AL5 that works a lot better. The link may have died a long time ago, but these tubes are useful. I have been searching for a replacement for the 417/5842. Now that the audiophile community has discovered the 5842 the prices for them have skyrocketed.
I have been testing the 5670/2C51 for an input tube. It is one of those triodes that works well with a CCS load. Put both sections in parallel.
6BQ7 and 6BK7 works good too.
It has been a while since I played with them, but the board that I have here runs both sections in parallel at 14 mA total. The plate voltage is set at about 160 volts. I use an IXYS CCS chip as the plate load, this sets the plate current. The plate voltage is set by the cathode resistor. There is quite a large tube to tube variation, and you may get better sound with less current. I am using these as driver tubes for SE triodes. There is not quite enough gain for a 2 tube design with 300B, good enough for 45. Plenty of gain if you use a line stage that has some gain.
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