http://www.ecp.cc/less-pressivo.html
Can be built for about $100 + a chassis, so $150 is quite reasonable. Sound, for the money, is great.
Can be built for about $100 + a chassis, so $150 is quite reasonable. Sound, for the money, is great.
The "he" is me, and no, I don't have any PCB's for sale. Really, this is a quite easy build, so the PCB is not necessary at all. The one thing that a PCB might make easier is the CCS, and you might find some CCS boards floating around here. You can also get CCS boards from Bottlehead, K&K Audio, and DIYHiFiSupply -- any of which will work fine.
Hi Dougie
This triode(d) PP 100% class A one can be DIY-build for less than 100 Euros, has won several local tube audio community shootouts and even can drive small speakers, too. A few copies of the original design even were built by others who participated in the shootouts with their own designs
Also, this circuit was shown as part of my ETF06 lecture to demonstrate what can be achieved with ultra-cheap "TV-tubes", using pentodes (or pentode sections) triode strapped.
Regards,
Tom
Dougie085 said:
This triode(d) PP 100% class A one can be DIY-build for less than 100 Euros, has won several local tube audio community shootouts and even can drive small speakers, too. A few copies of the original design even were built by others who participated in the shootouts with their own designs
Also, this circuit was shown as part of my ETF06 lecture to demonstrate what can be achieved with ultra-cheap "TV-tubes", using pentodes (or pentode sections) triode strapped.
Regards,
Tom
The one I built was pretty cheap. Two 6.3V filament transformers back to back into a voltage doubler, a 12AU7 direct-coupled to another 12AU7 White CF. It sounds gradually better and better
Construction Pics (disregard the signal schematic)
http://www.diyaudio.com/forums/showthread.php?postid=1233371#post1233371
Final signal schematic:
http://www.diyaudio.com/forums/showthread.php?postid=1233964#post1233964
Construction Pics (disregard the signal schematic)
http://www.diyaudio.com/forums/showthread.php?postid=1233371#post1233371
Final signal schematic:
http://www.diyaudio.com/forums/showthread.php?postid=1233964#post1233964
Dougie085 said:
Here's a thread dedicated to modding a Xiang Sheng 708B. There's a few folks selling them on ebay, and they've been getting cheaper since I got mine.
A few mods and 1 replaced valve, and it's a great sounding bit of kit! Check out my post under the name "hnb2907"
BTW; I did have a look at a few forums discussing the Little Dots, and the general view seemed to be that they're great sounding, but not always very reliable? I was also looking for something with a valve rectifier...
Cheers,
Chris.
AFAIK the little dot 2++ is reliable. The older version 2+ was not due to some poor quality chinese power tubes.
The mark III is a cracker, just be careful to buy either direct from them or through their seller on ebay davidzhezhe. Very good service from them and a 1 year warranty - and they pay shipping! How rare is that.
I was going to build an aikido based HP amp, but this was cheaper. I like building stuff, but when its available cheaper and in a nice chassis etc......
The mark III is a cracker, just be careful to buy either direct from them or through their seller on ebay davidzhezhe. Very good service from them and a 1 year warranty - and they pay shipping! How rare is that.
I was going to build an aikido based HP amp, but this was cheaper. I like building stuff, but when its available cheaper and in a nice chassis etc......
I'm currently planning both dsavitsk's Less-Pressivo and an Aikido based headphone amp for the future (though I may try to make a headphone amp out of John Broskie's cathode-coupled circuits instead of the Aikido).
I've heard the Aikido as headphone amp and can vouch that it is a really superb amp. Your output caps can get pretty huge and expensive if you'll be driving lower impedance cans (like Grados).
I've heard the Aikido as headphone amp and can vouch that it is a really superb amp. Your output caps can get pretty huge and expensive if you'll be driving lower impedance cans (like Grados).
woodturner-fran said:
My headphone preamp uses a high-temperature 450V 220uF electrolytic bypassed by a 2.2uF Solen. Not very expensive at all, and with a 32-ohm load, the cutoff is still a bit less than 20Hz if I recall correctly...
Even using those 100uF motor run caps wouldn't be that incredibly expensive, but the bulk factor of two per channel might become an issue.
If I were to re-do a headphone amp, I'd definitely use some kind of impedance matching transformer instead of the coupling cap, in all likelihood one of Edcor's cheapest XSE lines. At fractions of a watt of power, frequency response probably won't be an issue.
I used 220uF 400V electrolytics in my 5687 srpp/ 5842 white cathode follower design some years ago. I have to say the idea of 110V on one side of the capacitor and my ears a few mm away from the voice coils on the other made me very uncomfortable.
Should one of those caps fail it could be quite unpleasant...
My newest design uses output transformers Jack Elliano built to my specifications with 71A output tube and 5842 driver. I'm quite pleased with this design - drives my 32 ohm headphones directly off of the secondary and is dead silent. (The transformers have two 8 ohm secondaries - in parallel its an 8 ohm secondary, in series 32 ohms for the many pairs of 32 ohm headphones I own. Asking for Grados for xmas..
)
Should one of those caps fail it could be quite unpleasant...
My newest design uses output transformers Jack Elliano built to my specifications with 71A output tube and 5842 driver. I'm quite pleased with this design - drives my 32 ohm headphones directly off of the secondary and is dead silent. (The transformers have two 8 ohm secondaries - in parallel its an 8 ohm secondary, in series 32 ohms for the many pairs of 32 ohm headphones I own. Asking for Grados for xmas..
)
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