Hi, how about this ACRTK MK2
Revised Update 2018 ACRTK MK2
Differential Input NE5532
Replace discrete Front End with High Speed LM318 op IC
Crowbar DC protection
Over current Detection
Greetings
RELAY CANT protect speaker if amplifier fails
only crowbar can DO,
if amp no have fuses POWER supply will destroyed / amp burning up
but Crowbar will protect the speaker in this case
That is the final version of the DC protection module PCB designed with Project16 schema and optimized with his recommendationsCheers
Marc
Dear bandol83,
Kindly post the schematic along side the PCB. Then it will be more useful !
--gannaji
That is the final version of the DC protection module PCB designed with Project16 schema and optimized with his recommendations
Cheers
Marc
Hi Marc, thank you for your work . Waiting for your review.
Regards,
Boyet
Hi gannaj,
I didn't post the schematic for this design because it is not mine
Sorry,
Marc
If the design is posted on diyaudio, then you can definitely repost it. Else please give reference.
Hello,
I am impatient to finish my Quasi MOSFET amplifier therefor after having made some minor cosmetic modifications, I will send today the Gerber files to the PCB manufacturer
Since I have also some UPC1237 in stock and since the price of the PCB is less than the cost of the shipment, I have also made a small PCB to use these devices
Having few LM4702 and Sanken Darlington I have also designed an other PCB to use them...
I hope to have finished the Quasi for Christmas because I have a Quad KT120 tube amplifier waiting for me since several month
Bye,
Marc
I am impatient to finish my Quasi MOSFET amplifier therefor after having made some minor cosmetic modifications, I will send today the Gerber files to the PCB manufacturer
Since I have also some UPC1237 in stock and since the price of the PCB is less than the cost of the shipment, I have also made a small PCB to use these devices
Having few LM4702 and Sanken Darlington I have also designed an other PCB to use them...
I hope to have finished the Quasi for Christmas because I have a Quad KT120 tube amplifier waiting for me since several month
Bye,
Marc
Attachments
Thank you Hugh,
In fact this is the nice work of my friend Philippe that is living not too far from Bandol and who is good for mechanic and wiring while I am more involved on the design and build of the PCB, therefor this is a good combination
I have added some new pictures, now only the DC Speaker protection module and the volume knob are missing
And by the way, I have made a stupid mistake on the previous DC Speaker protection PCB, hopefully I could stop the production at PCBWay when Project16 told me that I have used a wrong library for the optocoupleur
I have enclosed the correct version which has been produced in the meantime and is now on the way to France, I hope to have finished the Quasi before Christmas
This will be a very compact amplifier, the chassis is nice but very small !
I have been so impressed by the quality of this small amplifier that I am thinking to make a bigger one, since I have some "Thermal Track" around, I have read the thread of Mihai Roender : RMI-FC100, a single stage audio power amplifier who seems to have made the "Ultimate" DIY transistors Amplifier
Hugh, I have read that you were very positive about this amplifier, isn't it ?
Best regards,
Marc
In fact this is the nice work of my friend Philippe that is living not too far from Bandol and who is good for mechanic and wiring while I am more involved on the design and build of the PCB, therefor this is a good combination
I have added some new pictures, now only the DC Speaker protection module and the volume knob are missing
And by the way, I have made a stupid mistake on the previous DC Speaker protection PCB, hopefully I could stop the production at PCBWay when Project16 told me that I have used a wrong library for the optocoupleur
I have enclosed the correct version which has been produced in the meantime and is now on the way to France, I hope to have finished the Quasi before Christmas
This will be a very compact amplifier, the chassis is nice but very small !
I have been so impressed by the quality of this small amplifier that I am thinking to make a bigger one, since I have some "Thermal Track" around, I have read the thread of Mihai Roender : RMI-FC100, a single stage audio power amplifier who seems to have made the "Ultimate" DIY transistors Amplifier
Hugh, I have read that you were very positive about this amplifier, isn't it ?
Best regards,
Marc
Attachments
Yes, Marc, you are correct. I wrote to Mihai Rauta in 2008 that I thought it to be a wonderful amplifier.
With another friend in Melbourne we built one using very similar common base topology in 2016 and discovered it had wonderful qualities.
I had developed another common base VAS, called the Maya, which I have been selling now for three years. It has a wonderful sound, and I'm confident that Mihai's amp would be wonderful too.
The clarity, lack of sibilance and intermodulation makes this VAS technique very, very good. Still, the VSQA is very good too, although it uses tried and true techniques, not quite so advanced as Mihai's design!
Congratulations on your beautiful work!
Merry Christmas to you, your family, and your audiophile friends!
Hugh
With another friend in Melbourne we built one using very similar common base topology in 2016 and discovered it had wonderful qualities.
I had developed another common base VAS, called the Maya, which I have been selling now for three years. It has a wonderful sound, and I'm confident that Mihai's amp would be wonderful too.
The clarity, lack of sibilance and intermodulation makes this VAS technique very, very good. Still, the VSQA is very good too, although it uses tried and true techniques, not quite so advanced as Mihai's design!
Congratulations on your beautiful work!
Merry Christmas to you, your family, and your audiophile friends!
Hugh
Hello Hugh,
After checking the speaker output to be sure that there was no significant DC voltage, I connected the speaker without the protection module (until I receive and build the module) to test the amplifier in the box...
Inside it is very full and the toroidal transformer is very close to all PCB, only few mm between them, but that doesn't seem to create problem. There is a very small noise from the transformer, probably a vibration noise but that should be disappear when I will close the box ?
I have a bigger problem with the volume control pot, when it is at the minimum or at the maximum there is absolutely no noise or hum, but when I increase the volume there is a significant hum which will disappear only when I reach the maximum
Have you an idea about the cause of this problem ? Tomorrow I will try with an external preamplifier and the volume of the Quasi at the maximum to see if the noise is still there or not...
Cheers,
Marc
After checking the speaker output to be sure that there was no significant DC voltage, I connected the speaker without the protection module (until I receive and build the module) to test the amplifier in the box...
Inside it is very full and the toroidal transformer is very close to all PCB, only few mm between them, but that doesn't seem to create problem. There is a very small noise from the transformer, probably a vibration noise but that should be disappear when I will close the box ?
I have a bigger problem with the volume control pot, when it is at the minimum or at the maximum there is absolutely no noise or hum, but when I increase the volume there is a significant hum which will disappear only when I reach the maximum
Have you an idea about the cause of this problem ? Tomorrow I will try with an external preamplifier and the volume of the Quasi at the maximum to see if the noise is still there or not...
Cheers,
Marc
What is the rated transformer that I should be choosing if going with either single or dual mono setup?
Also can I replace 1N4004 with 1N4007 diodes as I have them in hand?
I have started stuffing the boards with the available parts mostly Vishay Dale resistors and Wima caps.
An externally hosted image should be here but it was not working when we last tested it.
Thanks
Hi manniraj,
I am using a 300 VA 2 x 30 VAC transformer from TALEMA ( 55174-P1S2 TALEMA - Transformateur: toroidal | TME - Composants electroniques ) but you should probably take one with 115 / 230 V primary, it will give you about 40 VDC, I may test sometime a 35 VAC transformer to get about 47 VDC
You can use 1N4007, I am even using UF4007 because I have hundreds of them...
Best regards,
Marc
I am using a 300 VA 2 x 30 VAC transformer from TALEMA ( 55174-P1S2 TALEMA - Transformateur: toroidal | TME - Composants electroniques ) but you should probably take one with 115 / 230 V primary, it will give you about 40 VDC, I may test sometime a 35 VAC transformer to get about 47 VDC
You can use 1N4007, I am even using UF4007 because I have hundreds of them...
Best regards,
Marc