Hello,
I'm going to start building the F3 on Peter Daniels Boards soon.
For the PS I was able to get a decent pair of SMPS (48V, 6.2A) at a very good price.
Did anybody here try to use a SMPS for the F3?
As far as I understand the F3 draws a constant current and therefore a SMPS should work fine.
I just plan to upgrade some of the caps in the SMPS and to use 4.700uF near the AMP. The SMPS will go in a seperate case.
Any opinion and or experience?
Best regards
Josch
I'm going to start building the F3 on Peter Daniels Boards soon.
For the PS I was able to get a decent pair of SMPS (48V, 6.2A) at a very good price.
Did anybody here try to use a SMPS for the F3?
As far as I understand the F3 draws a constant current and therefore a SMPS should work fine.
I just plan to upgrade some of the caps in the SMPS and to use 4.700uF near the AMP. The SMPS will go in a seperate case.
Any opinion and or experience?
Best regards
Josch
go for it
use even greater amount of capacitance near the amp pcb
also - put some RC snubbers across them
use even greater amount of capacitance near the amp pcb
also - put some RC snubbers across them
After switching back to my el84 almarro 205 mk2, I noticed that it does a lot more bass/ lower midrange which gives instruments and male vocals more body. Reading the ZV9 article and especially the part about adding the feedback loop and a thread about ZV9 here I guess I could adjust the bottom response by changing the feedback.
My speakers are PHY-HP 8" 16ohm widebanders (with a super tweeter), so I'm guessing I'm getting a bit too much dampening from the amp? What would be a good point to start lowering the feedback (in terms of resistor value) or should I just go ahead and try disconnecting it and see how the amp sounds as a current source?
My speakers are PHY-HP 8" 16ohm widebanders (with a super tweeter), so I'm guessing I'm getting a bit too much dampening from the amp? What would be a good point to start lowering the feedback (in terms of resistor value) or should I just go ahead and try disconnecting it and see how the amp sounds as a current source?
If your 16R PHY-HPs are in a ported box, (B4 alignment) the current drive amp will produce a rather non-linear response at the low freqs and adjusting the f/back won't fix it - it's a speaker "problem" and the "solution" is either in re-designing the box (for B4 alignment) &/or preamp/electronic Xover (particularly for a B2 box - infinite baffle/closed box).
Before playing with feedback changes, try a very simple test - make up a headphone adapter to fit the amp's output terminals and simply plug in a good pair of headphones and have a good listen to what's going on - it won't blow your phones out if the volume is reasonable and the phones have 30R or higher -
Suggest the k701 AKG, Beyer 880, etc, etc, or any of the Stax (direct plugin) for checking - a very pleasant suprise is the F3 with headphones, especially with the "difficult" k701s.
Before playing with feedback changes, try a very simple test - make up a headphone adapter to fit the amp's output terminals and simply plug in a good pair of headphones and have a good listen to what's going on - it won't blow your phones out if the volume is reasonable and the phones have 30R or higher -
Suggest the k701 AKG, Beyer 880, etc, etc, or any of the Stax (direct plugin) for checking - a very pleasant suprise is the F3 with headphones, especially with the "difficult" k701s.
I have them installed in a huge open baffle (1.5x1.7m) like this http://phy-hp.com/English/Images/Communication/Baffle_plan_nb.jpg
The difference between the tube amp and this one is a bit like what is described in the article "Current Source Amplifiers and Sensitive / Full-Range Drivers". It would be interesting to see how the frequency response is changing when changing the amps.
The difference between the tube amp and this one is a bit like what is described in the article "Current Source Amplifiers and Sensitive / Full-Range Drivers". It would be interesting to see how the frequency response is changing when changing the amps.
I lost one chanel in my freshly buit F3. Duo to experiments with paralelling 220uf caps with 1uF foil caps, curent path connecting P1/R13 to R12 broke down while playing music. It probably induced high voltage impuls which burnt gates of all Mosfets in that chanel. That in turn caused high current passing ,through chanel and fuse was down too. I put stronger fuse and started to figure out what could be the damage but it was difficult since that chanel change into welding machinery for power resitors and they started to unsolder. Not sure enough what was the cause and effect I decided to rebuit it from scratch using spare PCB and came to conclusion that it is worth to change C2 and C3 from Nichicon Muse to Elna Silmic in both chanels as well as change Q2,Q4 for four pieces having exactly the same Vgs. So I did. At first I was convinced that I did something wrong as my F3 played a bit ugly. I always reconed C2,C3 as an aid in reducing THD rather than elements changing amplifer sound, so suspected any kind of error. I was wrong. After three hours sound started going back to normal. Frankly speaking it is no longer normal. F3 with the battery of 15x1000uF+220uF Elnas at the output and additionaly for C2,C3 is just amazing. It has no longer relaxed music presentation as Zen v9 had. It's very detailed and sweet at the same time. Brighter and a lot more charming than F5. More space and air in the music. I had Zen v9 since last year december, and went to great length in matching elements for my F5 which I bulit in february. Additionaly my F5 has a double "silent" PSU from Zen v5 article with two transformers. None the less F3 is just outstanding. Even old recordings from the seventies and late sixties sound great. Every instument just vibrate and plays the best it can. How about bass? There is no longer any kind of bass there are just instruments: bass guitar, double bass big drums etc. So music from my F3 is right now very emotionally involving. Maybe to much. but it was worth of all money and work spent. I know all of this is a bit emotional but let me shout:
Long live the Nelson !!!
Long live the Nelson !!!
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Just supplement to my post from 16 April 2011. Longer version of PCB is for big foil C3 40uF capacitor.
View attachment F3_melonhead_Copper.pdfView attachment F3_melonhead_Copper_Long.pdf
View attachment F3_melonhead_Copper.pdfView attachment F3_melonhead_Copper_Long.pdf
We found that adjusting r8 had a very large effect on the dc voltage at the output cap. (21v)
To get a 21 volt reading the left channel is a 2.2 bypassed with a 10 ohm and the right channel is bypassed with 20. Feedback is set the same and overall gain was 11db give or take.
My favorite thing about this amp is just how the decay on instruments is very natural. The amp is laid back without being at all slow or mushy. I'm using it with 7000uf of silmics and a pair of altec 604c. My favorite DIY amp so far.
To get a 21 volt reading the left channel is a 2.2 bypassed with a 10 ohm and the right channel is bypassed with 20. Feedback is set the same and overall gain was 11db give or take.
My favorite thing about this amp is just how the decay on instruments is very natural. The amp is laid back without being at all slow or mushy. I'm using it with 7000uf of silmics and a pair of altec 604c. My favorite DIY amp so far.
I have used my F3 since september. After first days I connected it with B1 buffer, as it sounded a bit more dynamic at low power levels.
Recently I found out that even though B1+F3 played very good, could say with a lot of “musicality”, but a little of "air" from concert room was lost
comparing to F3 playing alone. B1+F3 plays more "soft", more "rounded". The difference is just tiny but definately exists.
Anyone have noticed similar effect ?
Recently I found out that even though B1+F3 played very good, could say with a lot of “musicality”, but a little of "air" from concert room was lost
comparing to F3 playing alone. B1+F3 plays more "soft", more "rounded". The difference is just tiny but definately exists.
Anyone have noticed similar effect ?
F3 clone amp
Hi guys, I recently bought a used a Rawson F3 clone to try out on some TAD 4001 horns in an active environment. Because the 4001 is running at 110db+ and only covering 650 hertz and above the F3 isn't even breaking a sweat. I did try the amp using the passive TAD TN2 passive crossover network but the improvement going active and achieving 110+ db was remarkable.
A couple of impressions so far. Firstly it is dead quiet. I have many amps in the house and it is as quiet as my custom SET 45 monoblocks.
Secondly, it has extraordinary clarity and musicality. The TAD 4001 has ruthlessly exposed many so called high end amps. In fact this amp is the closest in sound quality to my reference SET 45 amps and in some areas exceeds them. It's a tribute to Nelson Pass to make such a transducer available to the DIY community.
After reading this thread I'd like to get the best out of the amp I can. Looking at the parts inside they seem to be of good quality but not great so I'd welcome some pointers on upgrades. I read some posts from Nelson about putting a bank of Elna caps but my amp seems to have different parts than the schematic posted. Here is a picture of the inside and has the following:
1. 8 x Nover Caps rated at 10,000 uf 63 volt (This is quite different from the single 1 x 15,000 cap and bank of 220s shown in the schematic.
2. Avel Y236651 250VA 18V+18V Toroidal Transformer
link here:
Avel Y236651 250VA 18V+18V Toroidal Transformer 122-620
For the power supply I'm thinking of replacing the existing one with a piltron. Anyone tried the pitron or other recommended options?
On the caps, I'm not sure what to do? I'm not sure why these are 8 x 10,000 for a start. I'd like to go down the Elna route but would require an army of them to replace 8 x 10k caps.
Cheers
DJ
Hi guys, I recently bought a used a Rawson F3 clone to try out on some TAD 4001 horns in an active environment. Because the 4001 is running at 110db+ and only covering 650 hertz and above the F3 isn't even breaking a sweat. I did try the amp using the passive TAD TN2 passive crossover network but the improvement going active and achieving 110+ db was remarkable.
A couple of impressions so far. Firstly it is dead quiet. I have many amps in the house and it is as quiet as my custom SET 45 monoblocks.
Secondly, it has extraordinary clarity and musicality. The TAD 4001 has ruthlessly exposed many so called high end amps. In fact this amp is the closest in sound quality to my reference SET 45 amps and in some areas exceeds them. It's a tribute to Nelson Pass to make such a transducer available to the DIY community.
After reading this thread I'd like to get the best out of the amp I can. Looking at the parts inside they seem to be of good quality but not great so I'd welcome some pointers on upgrades. I read some posts from Nelson about putting a bank of Elna caps but my amp seems to have different parts than the schematic posted. Here is a picture of the inside and has the following:
1. 8 x Nover Caps rated at 10,000 uf 63 volt (This is quite different from the single 1 x 15,000 cap and bank of 220s shown in the schematic.
2. Avel Y236651 250VA 18V+18V Toroidal Transformer
link here:
Avel Y236651 250VA 18V+18V Toroidal Transformer 122-620
For the power supply I'm thinking of replacing the existing one with a piltron. Anyone tried the pitron or other recommended options?
On the caps, I'm not sure what to do? I'm not sure why these are 8 x 10,000 for a start. I'd like to go down the Elna route but would require an army of them to replace 8 x 10k caps.
Cheers
DJ
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why don't you ask maker for upgrade policy ?
in any case - you profited - you paid for 3 , now you have 5
certainly F5 ( made as drek cheap chinese extending cord , model "Fire in the house")
that guy is not just a thief , he is dangerous ; one day some cheapskate will be burned or electrocuted
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No doubt, that's F5. Switch to other thread then. There are over 1000 posts so you've got a lot to read about it.
Man, I hate seeing exposed mains terminals like that. You could easily lay your hand right across that fuse while tweaking the bias or something. Please at least keep a secured top on it at all times when the kids / pets are around. Real easy to get a nasty shock with that kind of setup. And ONLY the LED wires are twisted, and nothing else? But, you said it's quiet so I guess that's all that matters.
hardly ;
this is the case where someone who owns TAD drivers ( and is most probably used to be informed about price/quality generally ) is willing to skimp on amp quality .
isn't odd to pay for an amp amount of greenies barely enough for a pair of decent 300Bs , and expect that amp in question is of any decent quality ?!
OK - let call buyer nothing more than naive , but TR's "work" is everything but naive .
one day someone will have major troubles because of that ;
and - fact that his amps are so praised on Audiofoolgone and similar "expert & aficionado" gathering places tells us more than enough about overall stupidity of members in question .
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