I have an antek 275-0V 275-0V 500mA + 2x 6.3V 5A power transformer, a Hammond 193K choke (2.6H 21R 300mA) and a 16x8x3 aluminum box. I figure I might as well throw together one of these because honestly the parts aren't being used. The thing is, I figure I want to build this amp so I can take it to college, so I'd like to make it integrated.
Here's my idea (too lazy to write everything out so i'll just cut and paste schematics)
cut off the input stage of the Simple El84, right where the 220K resistor is:
http://diyparadise.com/ultracompact.html
tack on the following linestage, maybe with a 100K alps pot in front:
here's the power supply. i'm getting a steady 320v into 160mA and around 255V into 16mA for the input stage. power across the 4K resistor peaks at around 1.4 watts so 5 watts should be plenty. the power transformer is set at 290V to allow for house AC being over 115V, into .5A with 4% regulation. That cap input should be 22uF as the 5u4GB's max seems to be 40.
edit: i was thinking either hammond 1608's or, for super budget, the edcor XPP10-8-8K for output.
how does it look? or am i seriously deranged personally, my only gripe is needing a filament transformer for the 5u4, but i needed its big voltage drop to make this work.
Here's my idea (too lazy to write everything out so i'll just cut and paste schematics)
cut off the input stage of the Simple El84, right where the 220K resistor is:
http://diyparadise.com/ultracompact.html
tack on the following linestage, maybe with a 100K alps pot in front:
An externally hosted image should be here but it was not working when we last tested it.
here's the power supply. i'm getting a steady 320v into 160mA and around 255V into 16mA for the input stage. power across the 4K resistor peaks at around 1.4 watts so 5 watts should be plenty. the power transformer is set at 290V to allow for house AC being over 115V, into .5A with 4% regulation. That cap input should be 22uF as the 5u4GB's max seems to be 40.
An externally hosted image should be here but it was not working when we last tested it.
edit: i was thinking either hammond 1608's or, for super budget, the edcor XPP10-8-8K for output.
how does it look? or am i seriously deranged personally, my only gripe is needing a filament transformer for the 5u4, but i needed its big voltage drop to make this work.
Hi
Hmm...the use if a 12AU7 may imply that some people around here won't reply 😀 so I do that... first...it should work! I believe that the input sensitivity for full output will be around 1VRMS, enough for standalone CD and DVD players, but you mention you will use this amp in college. I figure you may be using some portable source (MP3 player) and I don't know if those put out a full 1VRMS.
Erik
Hmm...the use if a 12AU7 may imply that some people around here won't reply 😀 so I do that... first...it should work! I believe that the input sensitivity for full output will be around 1VRMS, enough for standalone CD and DVD players, but you mention you will use this amp in college. I figure you may be using some portable source (MP3 player) and I don't know if those put out a full 1VRMS.
Erik
Erik, I think you might be referring to me! Sorry😉 Anyway, I promise I won't go on about the @#$$$ 12AU7 any more!
Seriously, though, I would just say that an SRPP stage seems to have worked better for other people - I've never tried it - with higher mu tubes. For example, 6SL7 has reportedly given better-sounding results than 6SN7. So, it may be that a 12AT7 or 12AX7 would be better in this case than a 12AU7.
Seriously, though, I would just say that an SRPP stage seems to have worked better for other people - I've never tried it - with higher mu tubes. For example, 6SL7 has reportedly given better-sounding results than 6SN7. So, it may be that a 12AT7 or 12AX7 would be better in this case than a 12AU7.
Hi Ray_moth
Actually I was referring to you, to SY, to EC8010, to Morgan Jones... 😀
Offtopic
If I understood well you have an amplifier based on Morgan Jones Crystal Palace. Could you share the schematic?
Erik
Actually I was referring to you, to SY, to EC8010, to Morgan Jones... 😀
Offtopic
If I understood well you have an amplifier based on Morgan Jones Crystal Palace. Could you share the schematic?
Erik
You don't really need a line stage with the Simple EL84. It will produce full output with a CD player or a tuner with a 'high' output connection. Even a standard tuner should be pretty close to full output.
I wouldn't complicate things if it isn't necessary. Just build it according to the schematic with the 100K pot in place. If you need a source selector you can use either a rotary switch for multiple inputs or a DPDT switch for two sources.
I wouldn't complicate things if it isn't necessary. Just build it according to the schematic with the 100K pot in place. If you need a source selector you can use either a rotary switch for multiple inputs or a DPDT switch for two sources.
Sorry Erik, I don't even know what the 'Crystal Palace' is like. I've never read Morgan's books or seen his designs.
My amp is my own design, with 6SL7 LTP splitter, 6SN7 differential driver and EL34 triode-strapped PP OP stage with fixed bias. It has cross-coupled NFB from OPT plates to splitter plates, similar to the arrangement used by Thorsten Loesch. The splitter has a pentode CCS in the tail. The splitter plates are coupled to the driver grids using step networks and there is plate-to-plate NFB between splitter and driver, for good balance.
My amp is my own design, with 6SL7 LTP splitter, 6SN7 differential driver and EL34 triode-strapped PP OP stage with fixed bias. It has cross-coupled NFB from OPT plates to splitter plates, similar to the arrangement used by Thorsten Loesch. The splitter has a pentode CCS in the tail. The splitter plates are coupled to the driver grids using step networks and there is plate-to-plate NFB between splitter and driver, for good balance.
Supposing I wanted to use some NFB, with maybe a 12AT7 in the totem pole instead to provide the gain that it would burn off, what would I connect to what to make it happen? The 8-ohm tap resistively connected to...?
ErikdeBest said:
I think that was SY - I asked in another thread if anyone had heard one as I have a bunch of 13E1s, and SY replied that he'd heard one with LS3/5As:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=88000&perpage=10&pagenumber=2
sorenj07 said:
You may use a resistor from a speaker output to the cathode of El84 if you want some feedback. Soundcard, iPod, CD player can give enough of power to drive el84 without any "pre". Use an input transformer like 600:10K if you need more, also with a symmetrical input you will eliminate a ground hum.
Sounds good - at this point I'm still leaning towards integrated but I'll consider both approaches. Anyway, here's one idea I had in the meantime. The 12AT7 stage has about 30dB of gain, and I put the feedback to the cathode of the bottom section. Would this work?
An externally hosted image should be here but it was not working when we last tested it.
Hi Raymoth
Thanks for replying. I must have confounded something along the discussions here.
Well..the hypothesis that EC8010 is a nichname of Morgan Jones... EC8010 tends to show lots of similar opinions to that of Morgan Jones: the use of EF184 as CCS, the EC8010 is a tube Morgan Jones uses in one of his RIAA preamps, EC8010 has built a Crystal Palace amplifier, (but physically it is different than Morgan Jones's one), the dislike of the ECC82 and in general both are very consequent - good engineers.
Don't know, but I rather suppose they are good friends!
Erik
Thanks for replying. I must have confounded something along the discussions here.
Well..the hypothesis that EC8010 is a nichname of Morgan Jones... EC8010 tends to show lots of similar opinions to that of Morgan Jones: the use of EF184 as CCS, the EC8010 is a tube Morgan Jones uses in one of his RIAA preamps, EC8010 has built a Crystal Palace amplifier, (but physically it is different than Morgan Jones's one), the dislike of the ECC82 and in general both are very consequent - good engineers.
Don't know, but I rather suppose they are good friends!
Erik
sorenj07 said:
Yes, but you'll have ZERO global feedback (capacitor shunted!)
Better shunt a grid of the 2'nd EL84.
Wavebourn said:
Does the fact that I bypass the cathode of the bottom 12AT7 mean that global feedback doesn't work?
Do you mean the 2nd EL84 as in the one on the bottom? I'm kind of confused...
nickds1 said:
Yes. That was me. I can assure you that, despite my dislike of ECC82/12AU7, I'm not Morgan Jones.😉 But Mr. Jones was kind enough to let me spend an evening running the CP through its paces.
As for EC8010, take a look at this post and all will be answered:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=39587&highlight=
sorenj07 said:
I'm curious, what does 'integrated' mean to you? I know what it means to me, but I'm curious what it means to you specifically.
-- Dave
well, it means an amp that has a driver stage and a volume control. of course i use the term pretty loosely but that's my general idea of it.Dave Cigna said:
yup.Wavebourn said:
in any case, i've decided to have less gain and forget about negative feedback, mostly because of the hassle involved. i'll probably just use a half 12au7 per side with a gain of about 20dB, in a grounded grid configuration. i need to resist the urge to make things more complicated than they need to be.
update: i've heard good things about the russian 6p14p tubes, and will probably use them as a replacement for the el84. i've got 10 random ones coming in the mail, which shouldn't be a problem with yeo's ingenous biasing method. i'm gravitating towards a grounded cathode 12bh7, half per channel, to drive them but if i can get discount russian dual triodes i'll go with that.
- Status
- Not open for further replies.