Just a note, please insure when you mount the LM337 and LM317 on your heatsink to use the insulating mounting kit correctly and check with meter that there are no short circuit to the heatsink from the Tab of these regulators, because it will blow fuses.
This check should also be done for all the Semiconductors (transistor and FET's)
The short circuit could be a cracked insulator or the TOP HAT that goes through the mounting hole on the LM317 or the LM337.
Do this check before you wire the PCB up to transformer and amp pcb.
If it happen after you checked it check again the first audible sign is a chattering relay. On the PSU board, this is normally a blown fuse.
As you can see the +V and –V regulator are based on the
LM317 and LM337 chips, these are drive current gain stages and have a very
simply current fold back current limit using 0.1R resistors to set this to
about 6A.
This current limit allow the 10,000uF and the SECA’ s
33,000uF capacitors to charge much slower and this will increase their life and
reduce the ON thump.
The basic just SECA board has a ripple voltage of about
500mV but with the PSU this is reduced to approx 5mV, this will show itself as
more detail at low levels when using the PSU together with the SECA.
The loses across the FET are there because we have a Gate
Source voltage of about 4 – 5V so the FET cannot drive to the +V rail, the
Darlington in the original has a voltage across it of about 2V and thus it cannot swing to the –V. So to
use the full range of the power/volts available we use the PSU board with all
the advantages mention before. In version 2 with the 2 FET’s the –V is not such
a problem as we only lose about 200mV max.
Now as the output approaches the max regulated +V or –V on
peaks the PSU ref is also moved and as it approaches 10V peak the PSU output
voltage changes and allow the FET/Darlington to get to the max voltage it can,
this gives you more punch and dynamic, this will show up on deeper bass and
fresh top end.
Thanks for that Col. Good to hear from you. :-) Interesting to see how he'd mounted the toroids! Also, I notice he praises the PSU boards... I've been thinking about those for mine... Do you supply them ready populated...? If so, how much...?
Thanks for that Col. Good to hear from you. :-) Interesting to see how he'd mounted the toroids! Also, I notice he praises the PSU boards... I've been thinking about those for mine... Do you supply them ready populated...? If so, how much...?
I have costed up the build for the PSU PCB's at £95.00 each + PP the max current is 6A with current fold back, this will charge the caps much slower and reduce the thump on most amps have in this style of design, the soft anti thump relay is now removed reducing costs and sounding better.
As you may be aware this PCB has SMD parts OK 1206 SMD parts and I felt it may be to hard for some folk, but I am happy to say those who have made it did a great job well done there is more projects soon.
Some with smaller SMD parts and some leaded beasties. have fun.
;;)
Righto. I've just tracked this (above) down from earlier in the thread... Colin, please can you confirm that the £95 + pp is the price for the populated PSU PCB (x2 obviously)...? If so, are these details still current...?
Does the PSU PCB need heatsinking...? If so, I'm guessing the best thing for me to do is to rotate my amp PCB 90 degrees and mount it "horizontally" to one end of the heatsink (like Undarra's below in fact), with the PSU board towards the other end, with both PCBs sharing the alumunium strip in the middle...?
Ben the PSU only dissipated low wattage so the bottom of the box would be OK.
Price OK
Thanks Colin. Not having to mount them on to the heatsink will make things easier! Though I may have to jiggle the toroids around a bit to make room on the base... That's within my capabilities! :-)
The Dynamic PSU makes a nice difference in terms of detail retrieval and bass response and is well worth the extra outlay which is modest for what you get sound wise.
The Dynamic PSU makes a nice difference in terms of detail retrieval and bass response and is well worth the extra outlay which is modest for what you get sound wise.
Thanks for the encouragement shoom...! And, for affirming my decision to press on. TBH every single report I've read of the effect of thhe dynamic PSU has been unequivocally praising, so my expectations are sky high!!!
From what I understand, given that Colin is assembling the boards for me, my fitting them into my amp should be quick and easy (even for me). I understand from Colin that he's well into the job already, so hopefully I'll have the dynamic PSUs here soonish. :-)
I’ve decided to register here as it seems to be SECA central
and I’m loving my build muchly.
I’ve been listening to the DIY ONE4AUDIO SECA for a while
now and like it more with each listen.
But feeling a little guilty for asking for more (Oliver
Twist Mode) was wondering about the possibility of a matching SECA PRE.
I noticed that you’ve published two circuit designs already
but for those who already have fairly good phono stages/HA the complexity of
the build may be a little off putting.
Maybe a modular approach will encourage some more building
activity which would be great.
So I’m going to suggest mono SECA Pre without PSU (Just the
circuit and leave the PSU to individual choice) so 2x for a stereo pre or would it be possible to post a circuit for
breadboard making use. Anyone know of any published circuits?
I’m really hoping that my above post causes no offence and
is seen as the compliment that your work deserves.
I've been following your build on pfm, it's quite lovely! Very well done, I hope to do similar one day.
SECA pre, you say? The question has been asked, a good while ago now, and Col has been slaving away ever since. I think it won't be that long! I saw a prototype circuit board for a production version last week.
That's you and I in the queue for a kit already, anyone want to join us? 8-}
As a short term stop-gap, the Tellurium Q Listen was one of Col's, and is very good indeed. Some of his older pre-amps surface from time to time, the likes of ID (Inca Designs) and Magnum both were SECA. Paul Quick will (as always) know much more than I.
Thanks for the positive words on my build over on PFM. But it’s
pretty shabby TBH.
But
I’ve had an aluminium
round up and soon will be starting efforts in creating a chassis of average
quality.
Half-baked but sounding wonderful.
Hi Collin
Great news on the SECA PRE.
It could be a good way of getting people building who may
not want to take on a PA with all of it’s sink and chassis magnificence not to mention the power requirements. A SECA
Pre may make a nice first taste for those with less experience..
I’m about average with SMD work so should muddle through.
Sorry but I'm a little new to these parts so just learning the language.
SECA semi design?
Tube. sounding interesting but adds a little complexity maybe.
TBH after hearing the super SECA PA I'm more than confident in your design abilities and also glad to have the chance to pair it up with whatever you decide is right.
Low voltage tubes can sound pretty darn fine. I have the Aikido Low voltage pre and it's a good sounding circuit to my ears.
Sorry but I'm a little new to these parts so just learning the language.
SECA semi design?
Tube. sounding interesting but adds a little complexity maybe.
TBH after hearing the super SECA PA I'm more than confident in your design abilities and also glad to have the chance to pair it up with whatever you decide is right.
Low voltage tubes can sound pretty darn fine. I have the Aikido Low voltage pre and it's a good sounding circuit to my ears.
Which tube have you in mind?
keep us posted.
I will use and have used the ECC83 mixed as either or semi-conductor out so two o/p one tube or one semi giving you the choice to which you like. I did this recently on a Bass Guitar amp sounded amazing.
ECC83 in my experience may be a little lacking in drive for longer IC. something with a little less gain but more grunt such as 6N6P (a great sounding brute) may work a little better.
Thanks Alan. Yes indeed. There's a brief video tutorial version of the instructions here. I've taken the liberty of edited Shoom's post to include the piccies.
ECC83 in my experience may be a little lacking in drive for longer IC. something with a little less gain but more grunt such as 6N6P (a great sounding brute) may work a little better.
Comments
And there is some signal generators also
http://download.cnet.com/s/oscilloscope/
http://download.cnet.com/s/signal-generators/
I have also had few good ones on Android's Software for a Huddle and Kindle HD thing.
They are not perfect but can be used to do fault finding.
The Sliding or Dynamic PSU
As you can see the +V and –V regulator are based on the LM317 and LM337 chips, these are drive current gain stages and have a very simply current fold back current limit using 0.1R resistors to set this to about 6A.
This current limit allow the 10,000uF and the SECA’ s 33,000uF capacitors to charge much slower and this will increase their life and reduce the ON thump.
The basic just SECA board has a ripple voltage of about 500mV but with the PSU this is reduced to approx 5mV, this will show itself as more detail at low levels when using the PSU together with the SECA.
The loses across the FET are there because we have a Gate Source voltage of about 4 – 5V so the FET cannot drive to the +V rail, the Darlington in the original has a voltage across it of about 2V and thus it cannot swing to the –V. So to use the full range of the power/volts available we use the PSU board with all the advantages mention before. In version 2 with the 2 FET’s the –V is not such a problem as we only lose about 200mV max.
Now as the output approaches the max regulated +V or –V on peaks the PSU ref is also moved and as it approaches 10V peak the PSU output voltage changes and allow the FET/Darlington to get to the max voltage it can, this gives you more punch and dynamic, this will show up on deeper bass and fresh top end.
Good to hear from you. :-)
Interesting to see how he'd mounted the toroids!
Also, I notice he praises the PSU boards...
I've been thinking about those for mine...
Do you supply them ready populated...? If so, how much...?
What's the price?
Blank cheque in post...?
And, yes: You build them; I'll fit them. :-)
Colin, please can you confirm that the £95 + pp is the price for the populated PSU PCB (x2 obviously)...?
If so, are these details still current...?
Does the PSU PCB need heatsinking...?
If so, I'm guessing the best thing for me to do is to rotate my amp PCB 90 degrees and mount it "horizontally" to one end of the heatsink (like Undarra's below in fact), with the PSU board towards the other end, with both PCBs sharing the alumunium strip in the middle...?
Thanks Colin.
Not having to mount them on to the heatsink will make things easier! Though I may have to jiggle the toroids around a bit to make room on the base... That's within my capabilities!
:-)
And, for affirming my decision to press on. TBH every single report I've read of the effect of thhe dynamic PSU has been unequivocally praising, so my expectations are sky high!!!
From what I understand, given that Colin is assembling the boards for me, my fitting them into my amp should be quick and easy (even for me).
I understand from Colin that he's well into the job already, so hopefully I'll have the dynamic PSUs here soonish. :-)
Many many thanks for working that through so quickly... :-)
I'm really excited!
Never easy though. Especially when I'm in full Nazi regalia.
That would be great timing. I'm working at home tomorrow, so a wee distraction mid-morning would be most welcome...
Hi Colin/All
I’ve decided to register here as it seems to be SECA central and I’m loving my build muchly.
I’ve been listening to the DIY ONE4AUDIO SECA for a while now and like it more with each listen.
But feeling a little guilty for asking for more (Oliver Twist Mode) was wondering about the possibility of a matching SECA PRE.
I noticed that you’ve published two circuit designs already but for those who already have fairly good phono stages/HA the complexity of the build may be a little off putting.
Maybe a modular approach will encourage some more building activity which would be great.
So I’m going to suggest mono SECA Pre without PSU (Just the circuit and leave the PSU to individual choice) so 2x for a stereo pre or would it be possible to post a circuit for breadboard making use. Anyone know of any published circuits?
I’m really hoping that my above post causes no offence and is seen as the compliment that your work deserves.
Begging bowl ready.
:o3I've been following your build on pfm, it's quite lovely! Very well done, I hope to do similar one day.
SECA pre, you say? The question has been asked, a good while ago now, and Col has been slaving away ever since. I think it won't be that long! I saw a prototype circuit board for a production version last week.
That's you and I in the queue for a kit already, anyone want to join us?
8-}
Hi Alan
Thanks for the positive words on my build over on PFM. But it’s pretty shabby TBH.
But
I’ve had an aluminium round up and soon will be starting efforts in creating a chassis of average quality.
Half-baked but sounding wonderful.
Hi Collin
Great news on the SECA PRE.
It could be a good way of getting people building who may not want to take on a PA with all of it’s sink and chassis magnificence not to mention the power requirements. A SECA Pre may make a nice first taste for those with less experience..
I’m about average with SMD work so should muddle through.
Another KISS design would be great.
Put me down on the list.
[URL=http://s1148.photobucket.com/user/colinwonfor1/media/listen basic inputs_zpsiw3ulpvv.jpg.html][IMG]http://i1148.photobucket.com/albums/o580/colinwonfor1/listen basic inputs_zpsiw3ulpvv.jpg[/IMG][/URL]
This one Shoom?
(Copy the 'Direct' link on p'bucket, paste it into the dialogue box for inserting images on your text toolbar here on 'chews.)
There's a brief video tutorial version of the instructions here.
I've taken the liberty of edited Shoom's post to include the piccies.