Sakis,
You are right. But there is another reason why audiphiles do not use Neutrik Speakon. There is no shining gold to look attractive! Just very good electrical connector with excellent properties and practicality. Also, Neutrik Speakon is not very expensive and most audiophiles (yes, I know many of them!) think that if something is not very expensive it cannot be good.
You are right. But there is another reason why audiphiles do not use Neutrik Speakon. There is no shining gold to look attractive! Just very good electrical connector with excellent properties and practicality. Also, Neutrik Speakon is not very expensive and most audiophiles (yes, I know many of them!) think that if something is not very expensive it cannot be good.
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Banana plugs are only fine or considered "safe" whilst European authorities and manufacturers won't commit to using safer alternatives. BFA connectors though, are a dreadful compromise whilst Speakons may be the future but their cost, size and cable fitting formats need to be adapted to suit domestic needs. Perhaps with a smaller outline, figure eight cable entry, for example.
You can be sure the audiophile parts manufacturers then won't take long to add rhodium plating on monocrystalline, oxy-free rare metal contacts or such to keep milking the big money from their clients, whatever product you like to mention.
Both Banana and BFA connectors are needlessly separate plugs for a single cable. Unless really solid and expensive locking collet types are used, typical Banana connections also prove to be insecure, very easily damaged and, way under-performing for their size and potential contact area. Only some types can be rated up to 15A. Some would be lucky to reach 1A without adding distortion. They are all too easily shorted and even a new born baby could pull most of them out of the speaker socket and suck on them. They are relics of 19th century electrical practice, popularized in the 1920s and revived with audio cult status in the 1980s, where I think they should stay, whatever imaginative qualities audiophiles might associate with them.
I think only the nickel plated steel spring connectors from the 1970s could be worse
You can be sure the audiophile parts manufacturers then won't take long to add rhodium plating on monocrystalline, oxy-free rare metal contacts or such to keep milking the big money from their clients, whatever product you like to mention.
Both Banana and BFA connectors are needlessly separate plugs for a single cable. Unless really solid and expensive locking collet types are used, typical Banana connections also prove to be insecure, very easily damaged and, way under-performing for their size and potential contact area. Only some types can be rated up to 15A. Some would be lucky to reach 1A without adding distortion. They are all too easily shorted and even a new born baby could pull most of them out of the speaker socket and suck on them. They are relics of 19th century electrical practice, popularized in the 1920s and revived with audio cult status in the 1980s, where I think they should stay, whatever imaginative qualities audiophiles might associate with them.
I think only the nickel plated steel spring connectors from the 1970s could be worse
P3A listening experiance
Dear Members,
Just to share some listening results of my build.
I used standard parts as per original schematic with BC546B at input,
BD139/140 for VAS and driver, and 2SC3281/1302 (Toshiba, scrap from old amp).
Very good sound as per built.
Recently, I changed the VAS to A1209 and the drivers are 2SC5171/1930.
PSU at 2 x 6800uf per amp. The input BC546B matched with <400hfe
This has resulted to a different sounding machine with very good bass and highs. The low levels are very noticeable.
I would like to thank Sakis for this valuable info. Truely a very fine amp.
Regards,
Raj.
Dear Members,
Just to share some listening results of my build.
I used standard parts as per original schematic with BC546B at input,
BD139/140 for VAS and driver, and 2SC3281/1302 (Toshiba, scrap from old amp).
Very good sound as per built.
Recently, I changed the VAS to A1209 and the drivers are 2SC5171/1930.
PSU at 2 x 6800uf per amp. The input BC546B matched with <400hfe
This has resulted to a different sounding machine with very good bass and highs. The low levels are very noticeable.
I would like to thank Sakis for this valuable info. Truely a very fine amp.
Regards,
Raj.
The P12 (figure 2) is interesting. However, I am not sure where the input ground should be: at the middle pin of the Trimpot (the positive side of C3), or zero-voltage ground ( the positive side of C3 ) ?
Any help? Thanks in advance.
Re: Simple 60 Watt Power Amplifier
the wire/trace connecting C3, VR2, D1, Ground (signal) and R12 is the signal ground for the input.
That wire needs to be extended upto the junction of C1 & R3, but not touching and then taken as a twisted pair to the input socket.
The AREA included inside the LOOP of Q1, C4, R12, C3 & R3 must be kept very small to minimise interference.
That wire needs to be extended upto the junction of C1 & R3, but not touching and then taken as a twisted pair to the input socket.
The AREA included inside the LOOP of Q1, C4, R12, C3 & R3 must be kept very small to minimise interference.
My P3A is working!
I finally finished my P3A last night and had it running ok. I have to say I found the initial switch on to be very nerve wracking. I only had some 18 ohm resistors to put in the fuse holders. - All went well though, nothing got hot and it seemed to check out okay.
I initially set the bias to 18mV giving a bias of about 27mA.
After listening for about half an hour and regularly checking for heat I thought it sounded a little edgy, thin and lacking bass.
I gradually increased the bias whilst checking all the while for heat or smoke and it is now running at about 50mV (75mA), but the amp is still cold, no heat other than the two linked drivers which are slightly warm to the touch.
Does this seem right to you experienced diyers? I was expecting a fair bit of heat from the heat sinks, - but no. Ive even run the amp at moderate levels today whilst home alone and still the thing is stone cold.
Ill do some more listening and biasing tonight and post again later to let you know how it all goes and how I feel about the sound quality, at the moment all I can really say is that it sounds 'OK'.
Below are some pictures as it is now. Not the neatest of layouts I know!
The block of MDF to the left of the TX in the first photo is for extra filter caps at a later date.
Kind regards
Roy.
I finally finished my P3A last night and had it running ok. I have to say I found the initial switch on to be very nerve wracking. I only had some 18 ohm resistors to put in the fuse holders. - All went well though, nothing got hot and it seemed to check out okay.
I initially set the bias to 18mV giving a bias of about 27mA.
After listening for about half an hour and regularly checking for heat I thought it sounded a little edgy, thin and lacking bass.
I gradually increased the bias whilst checking all the while for heat or smoke and it is now running at about 50mV (75mA), but the amp is still cold, no heat other than the two linked drivers which are slightly warm to the touch.
Does this seem right to you experienced diyers? I was expecting a fair bit of heat from the heat sinks, - but no. Ive even run the amp at moderate levels today whilst home alone and still the thing is stone cold.
Ill do some more listening and biasing tonight and post again later to let you know how it all goes and how I feel about the sound quality, at the moment all I can really say is that it sounds 'OK'.
Below are some pictures as it is now. Not the neatest of layouts I know!
The block of MDF to the left of the TX in the first photo is for extra filter caps at a later date.
Kind regards
Roy.
Attachments
There is some things that could be done in another way
1) VERY VERY CRITICAL ::: REMOVE THE FUSES !!! from the Dc line these are supposed to be located before the rectifier in the Ac area but better if you remove them totally on mains fuse will be fine .
2) second in case you got your shelf 6 capacitors you may as well get two more and relocate properly the all thing ..that will be
----Trafo and bridge in the middle 4 capacitors per side and symmetrical wiring bypassing them will also be a good thing ..
No bother about temperature with these heatsinks
kind regards
Sakis
1) VERY VERY CRITICAL ::: REMOVE THE FUSES !!! from the Dc line these are supposed to be located before the rectifier in the Ac area but better if you remove them totally on mains fuse will be fine .
2) second in case you got your shelf 6 capacitors you may as well get two more and relocate properly the all thing ..that will be
----Trafo and bridge in the middle 4 capacitors per side and symmetrical wiring bypassing them will also be a good thing ..
No bother about temperature with these heatsinks
kind regards
Sakis
Really, why ? But there's no fuse holders/fuses on the boards as shown on the original design. Please clarify. Thanks
Jacques
Yeah that statement makes no sense to me either.
If one uses close rated fast blow rail fuses then they need to be placed after the bulk filter caps otherwise the inrush current will cause nuisance blows left right and centre. It is reasonable to have local decoupling caps (say 47u to 1m) after the rail fuses but no more.
But what would I know, East is the expert...
If one uses close rated fast blow rail fuses then they need to be placed after the bulk filter caps otherwise the inrush current will cause nuisance blows left right and centre. It is reasonable to have local decoupling caps (say 47u to 1m) after the rail fuses but no more.
But what would I know, East is the expert...
Fuse holder are specified for about 6A rather low
if memory serves properly if one of the rails blow amplifier will latch to the other rail ( never had a P3A amplifier fused like that to know for sure )
Ranchu32 take a reading and see the difference between bypass and decoupling
Kind regards
Sakis
if memory serves properly if one of the rails blow amplifier will latch to the other rail ( never had a P3A amplifier fused like that to know for sure )
Ranchu32 take a reading and see the difference between bypass and decoupling
Kind regards
Sakis
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I did some more listening, adjusting & listening last night. Other than at a very low bias setting I was not aware of any difference to the SQ. I tried setting it to around 110ma at one point mainly to see if I could get any heat out of it, and it did become very slightly warm so I backed it off again to about 70ma.
There is absolutely no turn on or turn off thump and the offsets are steady around 14mV and 15mv.
Overall, my opinion on the SQ is that has a clean but slightly lean nature. On occasions it sounded a bit 'shouty', especially on female vocals. The biggest let down though was the bass - which didn't seem to be very tuneful - to my ears at least! Treble seemed fine but maybe a little more extension would be good.
Now please! These are only my opinions and I confess that I am no expert on SQ. All I can compare to are my friends systems and my own current system, which uses the power amp section of a NAD 3020A.
At one stage I put the NAD back on, and was immediately aware of its musical but warm, rounded presentation.
So there are some things I like about the P3A, e.g. power, dynamics and it seems to present a better stereo image.
Mr Sakis: The fuses, electrically, they are wired exactly the same as they were on Rodd's PCB's. I moved them off to make room for the 100uF decoupling caps. I'm not sure what you mean about the decoupling and bypass caps either could you explain please.
One thing I'm going to try is replacing the input cables with proper screened cables. Currently its just two wires twisted together with the screen added as an after thought when I read that the amp may oscillate.
Also, I have 6 more caps on order to fit on the left side which will then make it more symmetrical.
Do you think that because the amp will never get warm it will never settle down properly? Is it not said that an amp needs to warm up for a while after being switched on?
Sorry if I've gone on a bit! - I thought this was a smallish project where you build an amp, put it in a case and job done!
Now the fun starts...
Kind regards
Roy.
There is absolutely no turn on or turn off thump and the offsets are steady around 14mV and 15mv.
Overall, my opinion on the SQ is that has a clean but slightly lean nature. On occasions it sounded a bit 'shouty', especially on female vocals. The biggest let down though was the bass - which didn't seem to be very tuneful - to my ears at least! Treble seemed fine but maybe a little more extension would be good.
Now please! These are only my opinions and I confess that I am no expert on SQ. All I can compare to are my friends systems and my own current system, which uses the power amp section of a NAD 3020A.
At one stage I put the NAD back on, and was immediately aware of its musical but warm, rounded presentation.
So there are some things I like about the P3A, e.g. power, dynamics and it seems to present a better stereo image.
Mr Sakis: The fuses, electrically, they are wired exactly the same as they were on Rodd's PCB's. I moved them off to make room for the 100uF decoupling caps. I'm not sure what you mean about the decoupling and bypass caps either could you explain please.
One thing I'm going to try is replacing the input cables with proper screened cables. Currently its just two wires twisted together with the screen added as an after thought when I read that the amp may oscillate.
Also, I have 6 more caps on order to fit on the left side which will then make it more symmetrical.
Do you think that because the amp will never get warm it will never settle down properly? Is it not said that an amp needs to warm up for a while after being switched on?
Sorry if I've gone on a bit! - I thought this was a smallish project where you build an amp, put it in a case and job done!
Now the fun starts...
Kind regards
Roy.
Hi Royville. The amplifier driver transistors need to warm up to their average operating temperature before the bias becomes stable. Some people build P3a with varying distance between the bias controller transistor and the driver heatsink(s) but any air gap will slow the bias response to the driver temperature. If Q9 is in good contact with the driver heatsink, there will be much less need to wait for it to settle.
However, a hot heatsink for the output transistors will interfere with this and settling will take ages in some compact, small heatsinked builds. With your heatsinks, there will probably be no difference to concern you.
However, a hot heatsink for the output transistors will interfere with this and settling will take ages in some compact, small heatsinked builds. With your heatsinks, there will probably be no difference to concern you.
While we patiently wait for Nikosokey to repost his P3A I thought I'd share my experiences.
Well this is one of the first amplifiers I built, and for some reason I just can't stop tinkering with it. I'd conservatively estimate that over the past year, I've experimented with over a hundred different component substitutions in the quest for something different.
What I love about Rod's design is that it's so simple, yet produces very good sonics, and can be modified for even better performance.
For me the heart of the design is the bootstrapped voltage amplifier, and of course Rod's compound pair output stage. I've found that the best performance gain comes from simply substituting a better VAS transistor, reducing the miller cap and adding a phase lead.
Small input degeneration resistors seem to add some small refinement to the sound, without changing the sonic signature. This was most apparent when tested with the low noise & high gain BC550C LTP transistors shown. The added advantage of these degen resistors is that it make it trivial to balance the collectors by fine-tuning R4. I've tried adding a current mirror (with and without degeneration) - no difference in sound.
A high quality bootstrap cap is beneficial; I currently use a Nichicon KZ with excellent results. I've tried replacing it with an active current source, but prefer the sound with a good bootstrap cap.
I only listen to modern, digital sources, therefore, some of the other component values have been recalculated for a Low Impedance design.
The input filter shown is representative of my PCB design and a simplification of Rod's schematic. I don't advocate DC coupling per se., however my preamplifier (B1 buffer) has an output coupling cap so I've omitted the input cap on my PCB. HPF caps (when fitted) are soldered directly to the RCA connectors.
The circuit can be improved further but not without adding complexity. I like this version because its simple and still sounds like a P3A
Hi, add the entry degeneration worsens the outcome, ie, at least looking at the oscilloscope simulator = s (CIRCUIT ORIGINAL)
Hi,
Been doing some more listening / tinkering.
Tried screened cable on the input but that only made the amp sound a bit duller so took it out again. What made the biggest difference was removing one of my input caps (leaving just one 2.2mfd). Immediately, it sounded better, just sounded right and was easier to listen to and get into the music, - more focused and that sort of thing. So, maybe paralleling caps is not such a good thing!
Having listened for some time I think the amp has settled down (or I have) and I must say it does sound rather good now. Bass is musical, good mids and very good imaging, but I still think the treble is a little recessed.
The circuit I used to build this amp is Rod's latest circuit where R1 ad R3 are only 1k. So looking at the schematic with these values, has the input impedance been reduced, and maybe resulted in a kind of 'slugging' of the high frequencies? I'm no electronics guru,- just thought I'd ask. Have I seen a 'Direct Coupled' input schematic on here somewhere?
Any way, I will try 2k in positions R1 and R3 and see if it makes a difference.
The other thing I thought I'd like to try is a regulated supply for the front end, like this ...
http://www.diyaudio.com/forums/solid-state/214014-p3a-more-upgrades.html#post3052178
... but where would this be inserted into the original schematic? i.e. between Q4-R11 & R10-R12? or further left in the schematic?
Maybe at a later stage even consider my own PCB layout
Kind Regards
Roy.
Been doing some more listening / tinkering.
Tried screened cable on the input but that only made the amp sound a bit duller so took it out again. What made the biggest difference was removing one of my input caps (leaving just one 2.2mfd). Immediately, it sounded better, just sounded right and was easier to listen to and get into the music, - more focused and that sort of thing. So, maybe paralleling caps is not such a good thing!
Having listened for some time I think the amp has settled down (or I have) and I must say it does sound rather good now. Bass is musical, good mids and very good imaging, but I still think the treble is a little recessed.
The circuit I used to build this amp is Rod's latest circuit where R1 ad R3 are only 1k. So looking at the schematic with these values, has the input impedance been reduced, and maybe resulted in a kind of 'slugging' of the high frequencies? I'm no electronics guru,- just thought I'd ask. Have I seen a 'Direct Coupled' input schematic on here somewhere?
Any way, I will try 2k in positions R1 and R3 and see if it makes a difference.
The other thing I thought I'd like to try is a regulated supply for the front end, like this ...
http://www.diyaudio.com/forums/solid-state/214014-p3a-more-upgrades.html#post3052178
... but where would this be inserted into the original schematic? i.e. between Q4-R11 & R10-R12? or further left in the schematic?
Maybe at a later stage even consider my own PCB layout
Kind Regards
Roy.
Yes, that's the spot. However, there is some interaction between the front end and output stage via the power rails and this can sometimes be desirable. In my view, there is no need to gild the lily from a technical standpoint, unless noise or distortion are objectionable.
BTW, the resistors and caps at the input form a bandpass filter. Altering the input resistors and the caps changes the filter turnover frequencies and hence frequency response and RF filtering. Without Rod's sealed content (that you should not post here) we can't comment on the changes but if you stick to either implementation in full, you should have no problem with treble unless you are accustomed to something relatively bright or your speakers are a little weak in the top end themselves. I have heard about a dozen P3a builds over several years and I wouldn't say they are weak in the treble by design.