Hi,
O.K....
AND no reason I can think of why you can't do that with a SET as well.
What I critisise the SET brigade for is the way they go to ridiculous extremes and claim it sounds good.
From what I've seen from your work that's certainly not the case but some guys present 10 uF supplies and microwatt power and still make claims as if they'd invented hot water...
Sorry, but audio is still physics last time I checked.
Add a good dose of voodoo and you're in audio Nirvana...
Mister PS,
O.K....
AND no reason I can think of why you can't do that with a SET as well.
What I critisise the SET brigade for is the way they go to ridiculous extremes and claim it sounds good.
From what I've seen from your work that's certainly not the case but some guys present 10 uF supplies and microwatt power and still make claims as if they'd invented hot water...
Sorry, but audio is still physics last time I checked.
Add a good dose of voodoo and you're in audio Nirvana...
Mister PS,
Hrm...guess I should actually see what the heck a 6N6P is... I assumed it was a beefy triode, after all you don't want to be riding on transconductance, what with a 3 or 4k plate load...
Hey...ya know what? The other triode's plate will load down the 'free' end of the OPT...
Also, the CCS isn't a very good one seeing as IT'S SHUNTED BY CAPACITANCE! LOL can't believe that just occured to me..
Tim
I assumed it was a beefy triode, after all you don't want to be riding on transconductance, what with a 3 or 4k plate load...Hey...ya know what? The other triode's plate will load down the 'free' end of the OPT...
Also, the CCS isn't a very good one seeing as IT'S SHUNTED BY CAPACITANCE! LOL can't believe that just occured to me..
Tim
...what a nice start to the day...
Tim,
Many thanks for the amusement - I greatly enjoyed reading through your comments. I don't usually laugh out loud before my first coffee
Where to start...
As I stated earlier, to try to hit the cost boundary but use an OPT I needed to use a PP OPT. My first thought was to use a 3B7 a siamese double DHT as they are very cheap and have a reasonable mu (20) and Gm (2-2.5 mA/V) but I couldn't solve the signal and heater conflict cheaply enough (two channels one supply). It also needed a -ve supply for the long tail...
So back to IHTs. I like the 6N6P and it is happy with -6V bias so I could squeeze a ss constant current source under it! We're in business
Now psu... got a nice cheap Xfmr but any choice of chokes breaks the bank Oh well use RC filtering. It's PP so I don't need to work so hard on the PSU. I've got these nice cheap 3 section elec. so that's easy... Unfortunately 3 section RC psu with relatively large electrolytics sound crap - really crap - so how to release the sound of the 6N6Ps...
I know use ultrapath philosophy and get the psu out of the signal path! Disadvantage is that it's not pp for signal but it is pp for d.c. Cheap OPT and better PSRR A win-win!
Tim,
Have another look at the OPT configuration - 12.5k:8R.
Look at the winding ratio... now consider the typical load driving a power amp...
What reflected impedance does that give the 6N6P as anode load for audio?
Not 3-4K is it...
Colt 45, if you have 6N6p for 4 euro - I'll have 50.
ciao
James
Tim,
Many thanks for the amusement - I greatly enjoyed reading through your comments. I don't usually laugh out loud before my first coffee
Where to start...
As I stated earlier, to try to hit the cost boundary but use an OPT I needed to use a PP OPT. My first thought was to use a 3B7 a siamese double DHT as they are very cheap and have a reasonable mu (20) and Gm (2-2.5 mA/V) but I couldn't solve the signal and heater conflict cheaply enough (two channels one supply). It also needed a -ve supply for the long tail...
So back to IHTs. I like the 6N6P and it is happy with -6V bias so I could squeeze a ss constant current source under it! We're in business
Now psu... got a nice cheap Xfmr but any choice of chokes breaks the bank
Oh well use RC filtering. It's PP so I don't need to work so hard on the PSU. I've got these nice cheap 3 section elec. so that's easy... Unfortunately 3 section RC psu with relatively large electrolytics sound crap - really crap - so how to release the sound of the 6N6Ps...I know use ultrapath philosophy and get the psu out of the signal path! Disadvantage is that it's not pp for signal
but it is pp for d.c. Cheap OPT and better PSRR A win-win! Tim,
Have another look at the OPT configuration - 12.5k:8R.
Look at the winding ratio... now consider the typical load driving a power amp...
What reflected impedance does that give the 6N6P as anode load for audio?
Not 3-4K is it...
Colt 45, if you have 6N6p for 4 euro - I'll have 50.
ciao
James
By brain
Ok so even if the OPT isn't contributing any appreciable load, the other tube half is. Why is the CCS use at all, and why is it negated with caps?
Lesse... 6N6P mu circa 20 IIRC (was talking with Colt and he looked it up for me), but since the OPT's winding ratio is 40:1, or 20:1 for one half the transformer as is used here, net gain won't be greater than one. Though it will provide additional current if the signal source is high impedance, and adds a volume control to the string.
I bet if you changed the CCS to a resistor, and got rid of those spare caps (at the CCS and PSU), you'd have enough money to squeeze in a choke.
Lesse... 75mA choke... AES sells a 10H 90mA Triad choke, $18. As for the circuit, you can use the same PT and caps, paralleling the two last ones as shown. Should be good and solid and sim shows the same negligible level of hum.
Tim
Lesse... 6N6P mu circa 20 IIRC (was talking with Colt and he looked it up for me), but since the OPT's winding ratio is 40:1, or 20:1 for one half the transformer as is used here, net gain won't be greater than one. Though it will provide additional current if the signal source is high impedance, and adds a volume control to the string.
I bet if you changed the CCS to a resistor, and got rid of those spare caps (at the CCS and PSU), you'd have enough money to squeeze in a choke.
Lesse... 75mA choke... AES sells a 10H 90mA Triad choke, $18. As for the circuit, you can use the same PT and caps, paralleling the two last ones as shown. Should be good and solid and sim shows the same negligible level of hum.
An externally hosted image should be here but it was not working when we last tested it.
Tim
Hi John,
The inductance is a problem - one additional reason for more current through the triode to reduce Rp a bit more.... Using a cheap OPT one is always going to suffer with poor bass extension. The circuit actually cheats a bit - the 220uF yields a small tip up in bass response before it drops off - so subjectively the effect is a bit like the LS3/5a. This is fixed by using Hammond 1609s at another 50euros cost - it's also worth using a twin LC psu removing the decoupling caps and going true PP. Replace the pot with a TVA doing PP splitting and you have my own pre Well almost...
ciao
James
The inductance is a problem - one additional reason for more current through the triode to reduce Rp a bit more.... Using a cheap OPT one is always going to suffer with poor bass extension. The circuit actually cheats a bit - the 220uF yields a small tip up in bass response before it drops off - so subjectively the effect is a bit like the LS3/5a. This is fixed by using Hammond 1609s at another 50euros cost - it's also worth using a twin LC psu removing the decoupling caps and going true PP. Replace the pot with a TVA doing PP splitting and you have my own pre
Well almost...ciao
James
Hi Tim,
Actually I tried that and it breaks the bank. Look at the cost breakdown and the two ccs costs a total of 1.3 euro...
Of course, the decoupling caps add up to the choke cost and one could throw them away - but I know the difference between having the Audyn bypassing the psu output and not and I wouldn't be without it - I think..
I don't think it's a perfect or even an optimum design - I thought it interesting to do a WOT pre for 100euros and interesting enough to post...
I hadn't intended to build this but I might knock this up with the psu your way to see what it sounds like and then try my way and see which works better as I really don't know which would be better.
Thanks
James
Actually I tried that and it breaks the bank. Look at the cost breakdown and the two ccs costs a total of 1.3 euro...
Of course, the decoupling caps add up to the choke cost and one could throw them away - but I know the difference between having the Audyn bypassing the psu output and not and I wouldn't be without it - I think..
I don't think it's a perfect or even an optimum design - I thought it interesting to do a WOT pre for 100euros and interesting enough to post...
I hadn't intended to build this but I might knock this up with the psu your way to see what it sounds like and then try my way and see which works better as I really don't know which would be better.
Thanks
James
A simple Aikido 6N3P preamp running off of a small high voltage module can be built for less than $100 and runs from a 12V supply. You might even be able to build it with 6N6P outputs and drive 32 ohm headphones with it.
Here's the module I use for my line and phono stages. A simple 2k/47u filter works well, the switching freq is 75 khz. You would need one per channel if building the 6N6P version (~40ma/channel@265v)
http://www.ebay.ca/itm/332079780531?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT
This is a phono/headphone combo I built the other day for about $125 CAD.
Here's the module I use for my line and phono stages. A simple 2k/47u filter works well, the switching freq is 75 khz. You would need one per channel if building the 6N6P version (~40ma/channel@265v)
http://www.ebay.ca/itm/332079780531?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT
This is a phono/headphone combo I built the other day for about $125 CAD.
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6N16B run from 12V can add nice clipping.
Yes it can! Luckily I use a 12V supply to power an SMPS to get my 300V
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