hi Maxlorenz,
Have you tried to A/B the prev PS?
Is it possible that you share your charge transfer PS circuitry with me as I am interested to build a similar ZCA with charge transfer PS? Thanks.
Lee
Have you tried to A/B the prev PS?
Is it possible that you share your charge transfer PS circuitry with me as I am interested to build a similar ZCA with charge transfer PS? Thanks.
Lee
Guys
It is a well known fact that an audio amplifier only modulates the power supply (PS).
The ZCA is a special beast but not alone. It is very simple but relies heavily on the quality of its PS. It can do little more. Sometimes I use lead based solder and all carbon resistors 'cause that's the sound I want and other times I use silver based solder and metal film.....
The ZCA is very musical and very delicate. The PS is strictly "old school". Don't you just love the sound of a choked PS? I do. Some freaks roll rec tubes for a better sound. "Rec tubes, NO, you are joking". No it is true. Try it.
I am just finishing (as I type this) a valve rectifier/choked based PS for a two stage wooden Tea Box enclosed valve (Golden Dragon) preamp. 'cause that is the sound I want.
I love the "smarter" PS(s) but sometimes "old school" cuts deeper and leaves much prettier scars. Dig deep for more pain and pleasure.
The ZCA IS! Anything else IS NOT! The best PS possible is just the start but it could also be the finish.
Mark
It is a well known fact that an audio amplifier only modulates the power supply (PS).
The ZCA is a special beast but not alone. It is very simple but relies heavily on the quality of its PS. It can do little more. Sometimes I use lead based solder and all carbon resistors 'cause that's the sound I want and other times I use silver based solder and metal film.....
The ZCA is very musical and very delicate. The PS is strictly "old school". Don't you just love the sound of a choked PS? I do. Some freaks roll rec tubes for a better sound. "Rec tubes, NO, you are joking". No it is true. Try it.
I am just finishing (as I type this) a valve rectifier/choked based PS for a two stage wooden Tea Box enclosed valve (Golden Dragon) preamp. 'cause that is the sound I want.
I love the "smarter" PS(s) but sometimes "old school" cuts deeper and leaves much prettier scars. Dig deep for more pain and pleasure.
The ZCA IS! Anything else IS NOT! The best PS possible is just the start but it could also be the finish.
Mark
Hi Lee, Mark, 🙂
Yes, the ZCA is a lovely and especial amp. It is also inexpensive to build. I don't know why we are not a legion of builders of this amp which allows for a good taste of single ended Class A.
Now, we as DIYers can and ought to try alternatives.
I found that PS mods in the way of the "never connected" PS and the charge transfer PS (which presently has two versions) represent a worthy improvement. For example, even though I consider myself an ethernal begginer, I suspect the charge transfer PS sounds like the valve rectified circuits by dimishing the noise transfered from the mains and that generated on the SS rectifiers, but has the advantage of the high current capability of the later.
Charge transfer PS, MK I:
http://picasaweb.google.com/lh/photo/rOgiSl8IVgPdqOcKLPkbNA?feat=directlink
"Floating" charge transfer PS, or MK II:
http://picasaweb.google.com/lh/photo/UyHCdD9B2QkYmc8HPORBqg?feat=directlink
Mr Jonathan Carr gave me a tip: put a choke (which I think ca be a small one; or even a resistor could do) between Tx's secondaries and rectifiers. He and the inventor, ecdesigns, favors the second version.
I hope I don't boder you, Mark, by including this on your thread...
The case is that I am astonished by the effect the circuit has on sound (on different equipment), and no I did not make ABA comparison with the ZCA. No time. I will someday check it with my humble scope.
Cheers,
M
Yes, the ZCA is a lovely and especial amp. It is also inexpensive to build. I don't know why we are not a legion of builders of this amp which allows for a good taste of single ended Class A.
Now, we as DIYers can and ought to try alternatives.
I found that PS mods in the way of the "never connected" PS and the charge transfer PS (which presently has two versions) represent a worthy improvement. For example, even though I consider myself an ethernal begginer, I suspect the charge transfer PS sounds like the valve rectified circuits by dimishing the noise transfered from the mains and that generated on the SS rectifiers, but has the advantage of the high current capability of the later.
Charge transfer PS, MK I:
http://picasaweb.google.com/lh/photo/rOgiSl8IVgPdqOcKLPkbNA?feat=directlink
"Floating" charge transfer PS, or MK II:
http://picasaweb.google.com/lh/photo/UyHCdD9B2QkYmc8HPORBqg?feat=directlink
Mr Jonathan Carr gave me a tip: put a choke (which I think ca be a small one; or even a resistor could do) between Tx's secondaries and rectifiers. He and the inventor, ecdesigns, favors the second version.
I hope I don't boder you, Mark, by including this on your thread...
The case is that I am astonished by the effect the circuit has on sound (on different equipment), and no I did not make ABA comparison with the ZCA. No time. I will someday check it with my humble scope.
Cheers,
M
Sorry, I misread the following sentence:
He meant on normal supplies...not necessarily the modded one.
He meant on normal supplies...not necessarily the modded one.
Hi Max,
I was wondering whats the voltage output of your "Floating" charge transfer PS, its because the TX sec is only 9v * 2 instead of the required 24v if the original ZCA schematic is followed.
How many ampre do you expect this PS to output?
Thanks.
Lee
I was wondering whats the voltage output of your "Floating" charge transfer PS, its because the TX sec is only 9v * 2 instead of the required 24v if the original ZCA schematic is followed.
How many ampre do you expect this PS to output?
Thanks.
Lee
Guys
Keep me in the thread. I'm interested in any "chat" about the ZCA.
I'm throwing down the challenge here: Who will be the first to build the transistors version??
I have toyed with the idea but to get ideas to make music I need ACTION. In this area I have been slack.
Oh well back to my Rec valve powered remote PS for another Tea Box valve preamp.
Keep me in the thread. I'm interested in any "chat" about the ZCA.
I'm throwing down the challenge here: Who will be the first to build the transistors version??
I have toyed with the idea but to get ideas to make music I need ACTION. In this area I have been slack.
Oh well back to my Rec valve powered remote PS for another Tea Box valve preamp.
Hi Lee,
The circuit posted was borrowed from another project. It can be modified as you need. I think if you use enough capacitance and power Darlingtons plus high current Schottkys
you can reach very high current (but Tx and R must be capable of handling it).
Hi Mark,
Do you refer to your own transistor preamp or to the charge transfer supply?
I will surelly try your preamp ASAP (which means I don't know when I will get the free time to...)
Cheers,
M
The circuit posted was borrowed from another project. It can be modified as you need. I think if you use enough capacitance and power Darlingtons plus high current Schottkys
you can reach very high current (but Tx and R must be capable of handling it).
Hi Mark,
Do you refer to your own transistor preamp or to the charge transfer supply?
I will surelly try your preamp ASAP (which means I don't know when I will get the free time to...)
Cheers,
M
maxlorenz said:
I was referring to the to the amp and not the PS. Though I have (as my main system) large monoblock KT88 push-pull power amps, I am interested in exploring low power bi-polar transistor amps. Appears extreme but I believe bi-polars set-up right may produce some very exciting results. The ZCA showed that simple amps can sound good. Now to move from FETs to bi-polar. May be even a two stage affair.
E-mail me I have some photos of my remote PS valve rectified Twinings Tea Box valve preamp I would like to send you.maxlorenz said:
oki doki
constructed......
sounds like a sweet litle thingy .....
plays very nice ( scope readings also very nice .... )
but power is very very low ..... for sure will need very effective speakers
will post pictures tomorow or something
thanks mark !!!!!
constructed......
sounds like a sweet litle thingy .....
plays very nice ( scope readings also very nice .... )
but power is very very low ..... for sure will need very effective speakers
will post pictures tomorow or something
thanks mark !!!!!
ok ....... a couple of thigs more
i used a pair of almost crapy speakers for the testing .....
the speakers actually sounded very very nice ( ?????)
reckordings that i had in mind that sounded hursh and noisy arround high with this amp sound relativelly much cleaner ....
bass is tight ( but not much i think ) i will consider a better or biger input cap tomorow
will see il have extensive tests and photos after 12 hours
regards sakis
i used a pair of almost crapy speakers for the testing .....
the speakers actually sounded very very nice ( ?????)
reckordings that i had in mind that sounded hursh and noisy arround high with this amp sound relativelly much cleaner ....
bass is tight ( but not much i think ) i will consider a better or biger input cap tomorow
will see il have extensive tests and photos after 12 hours
regards sakis
Any consideration on the class A PP complimentary circuit variation to rid yourselves of that output cap?
This looks soooo much like the Babozen (Zen V5 with JFET input) with 2SK1058/2SJ162 instead of the IRFP240/IRFP9240
I have 4 2SK1058 and 4 2SJ162, as well as a few 2SK170BL and 2SJ74BL as well as a 400 VA 20-0 20-0 tranny in my parts bin......
Also put a 2k pot in where the two 1K resistors are to set offset and bias...
From the French site
http://pagesperso-orange.fr/jm.plantefeve/sche.html
This looks soooo much like the Babozen (Zen V5 with JFET input) with 2SK1058/2SJ162 instead of the IRFP240/IRFP9240
I have 4 2SK1058 and 4 2SJ162, as well as a few 2SK170BL and 2SJ74BL as well as a 400 VA 20-0 20-0 tranny in my parts bin......
Also put a 2k pot in where the two 1K resistors are to set offset and bias...
From the French site
http://pagesperso-orange.fr/jm.plantefeve/sche.html
Attachments
Hi all,
I've successfully biased my ZCA with 8 ohm resistors for a bias current of 1.4 amps. I have a 2x18VAC 250VA transformer with MUR860 rectifiers which gives me 23 volt rails after filtering (CLC 10,000uF -> 10mH -> 10,000uF). Each channel has its own secondary and filtering. The power resistors run hot, but they are on the outside of my chassis so they aren't too much of a problem. I'm using a low rpm 12VDC 120mm Nexus fan to actively cool the heatsinks. They are very nice quiet fans. A bit pricey though. It keeps the sinks under ~35c (95F). I haven't been brave enough to try it without the fan yet. All the other components are as specified by Mark.
There is noticeably more gain. Sound is a bit edgier, but it still sounds like a ZCA.
I know it seems like an odd place to post this... but I think this is the most informative discussion of Mark's ZCA on diyAudio.
I've successfully biased my ZCA with 8 ohm resistors for a bias current of 1.4 amps. I have a 2x18VAC 250VA transformer with MUR860 rectifiers which gives me 23 volt rails after filtering (CLC 10,000uF -> 10mH -> 10,000uF). Each channel has its own secondary and filtering. The power resistors run hot, but they are on the outside of my chassis so they aren't too much of a problem. I'm using a low rpm 12VDC 120mm Nexus fan to actively cool the heatsinks. They are very nice quiet fans. A bit pricey though. It keeps the sinks under ~35c (95F). I haven't been brave enough to try it without the fan yet. All the other components are as specified by Mark.
There is noticeably more gain. Sound is a bit edgier, but it still sounds like a ZCA.
I know it seems like an odd place to post this... but I think this is the most informative discussion of Mark's ZCA on diyAudio.
You have manage to to keep the original ZCA formular but take the design and concept to a new level. The ZCA formular of resitive load no more than 15ohms load resistor, single FET amp can have so many build variations and yours is one of the best I have seen.
Excellent build. I would like to see more photos and more detail. I would also like to see your final schematic for both amp and power supply with all the values in detail.
Last edited:
Thanks for the kind words Mark. I did try and stay true to the original ZCA recipe.
It is all wired point-to-point. There are some internal pics here: http://www.diyaudio.com/forums/soli...ur-solid-state-pics-here-131.html#post2115577. The current version doesn't have the bridge rectifiers. I'm still tweaking some stuff, but I will be sure to post a final schematic when I'm done.
I'm driving it with an EMU 0404 usb through a passive low pass shelving filter which gives me some bass EQ and cuts the input signal by 10 dB. The ZCA is driving my 95 dB/w 3-ways. Each channel has an Usher 15HM, Audax PR170N0, and CSS LAR1 ribbon.
It is all wired point-to-point. There are some internal pics here: http://www.diyaudio.com/forums/soli...ur-solid-state-pics-here-131.html#post2115577. The current version doesn't have the bridge rectifiers. I'm still tweaking some stuff, but I will be sure to post a final schematic when I'm done.
I'm driving it with an EMU 0404 usb through a passive low pass shelving filter which gives me some bass EQ and cuts the input signal by 10 dB. The ZCA is driving my 95 dB/w 3-ways. Each channel has an Usher 15HM, Audax PR170N0, and CSS LAR1 ribbon.
Nice ZCA
Hi roger_lew
What a great looking ZCA you've got there ...seems you got two of them ? ( last picture ). I hope you'll add all your pictures to the diyaudioprojects.com gallery too, so people there also are able to see this fine build. Good job.
I'm also building the ZCA right now, but it's more an ugly ( scrap/recycling ) build version.
Hi roger_lew
What a great looking ZCA you've got there ...seems you got two of them ? ( last picture ). I hope you'll add all your pictures to the diyaudioprojects.com gallery too, so people there also are able to see this fine build. Good job.
I'm also building the ZCA right now, but it's more an ugly ( scrap/recycling ) build version.
Mr Lew,
depends on the contest entries, looks pretty charming to me.
Especially the hovering fan, but also the heatsink clamps and the case work.
matching ZCA and BoZ
This is first post on the forum (I've been lurking for a while) so hello all.
I've built a ZCA (my first DIY amp and first major electronics project in many years). The learning curve was quite steep to say the least, but I managed not to blow myself or anybody/thing up. And oh my god, I never realised, it sounds amazing! Thanks to Mark for the design and all the forum members (especially Kinnja) who posted their build experiences in this thread. I followed Mark's circuit for the gain stage and built a cap mult for the PS based on Kinja's circuit (posted in this thread), all point-to-point wiring. My setup is vanilla computer soundcard > ZCA > Celestion Ditton 15XR speakers. Even with this modest setup, as I said, the sound is really great - warm and detailed.
I was also interested to see what the ZCA sounded like with a preamp, so I next built a Pass Bride of Zen (circuit here: http://www.passdiy.com/pdf/brideofzen.pdf). With the preamp, the sound is even better (and a lot louder too). Both amp and preamp are open-air on MDF at the moment, and I'm just getting the stuff together to build cases for each.
My questions are about matching the amp and preamp. What I'd like to do is have the volume control on the BoZ preamp output, and no volume pot (just inputs and outputs) on the ZCA. I'm using a dual 10K for P101 on the output of the BoZ.
* Is it OK to remove the two 47K input pots from the ZCA?
* Do I need to think about anything else when matching the BoZ and ZCA so they work best together?
Cheers.
This is first post on the forum (I've been lurking for a while) so hello all.
I've built a ZCA (my first DIY amp and first major electronics project in many years). The learning curve was quite steep to say the least, but I managed not to blow myself or anybody/thing up. And oh my god, I never realised, it sounds amazing! Thanks to Mark for the design and all the forum members (especially Kinnja) who posted their build experiences in this thread. I followed Mark's circuit for the gain stage and built a cap mult for the PS based on Kinja's circuit (posted in this thread), all point-to-point wiring. My setup is vanilla computer soundcard > ZCA > Celestion Ditton 15XR speakers. Even with this modest setup, as I said, the sound is really great - warm and detailed.
I was also interested to see what the ZCA sounded like with a preamp, so I next built a Pass Bride of Zen (circuit here: http://www.passdiy.com/pdf/brideofzen.pdf). With the preamp, the sound is even better (and a lot louder too). Both amp and preamp are open-air on MDF at the moment, and I'm just getting the stuff together to build cases for each.
My questions are about matching the amp and preamp. What I'd like to do is have the volume control on the BoZ preamp output, and no volume pot (just inputs and outputs) on the ZCA. I'm using a dual 10K for P101 on the output of the BoZ.
* Is it OK to remove the two 47K input pots from the ZCA?
* Do I need to think about anything else when matching the BoZ and ZCA so they work best together?
Cheers.
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