I think I will use two EI48 type transformers2x12V.
That was my plan in the beginning but then I rather opted for potentiometer option. I plan to use neutrik 1/4 jack for chassis mounting. With this option I also avoid to have long wires from pot to the PCB. Another thing is I want the whole thing to squeeze in 160mm x 100mm enclosure, something like this: HAMMOND 1445N1601RD.
Last edited:
PCBs are in!
Hi,
It has been a while since I last worked on this project...
This week I received PCBs. As you can see I have increased size of it, which is now 160mm*160mm. Almost all the components will fit directly to the PCB with exception of I/O connectors and IEC inlet.
BR,
Aleš
Hi,
It has been a while since I last worked on this project...
This week I received PCBs. As you can see I have increased size of it, which is now 160mm*160mm. Almost all the components will fit directly to the PCB with exception of I/O connectors and IEC inlet.
BR,
Aleš
Attachments
Hi Raul,
thank you for the comment. What will the price be when it comes out, I do not know. Haven't done any calculations yet.
Yesterday I placed components on to the PCB and checked if regulators are working, no problem here. Delay is also working fine and it turns on after around 5 seconds. Opamps are now MUSES8920. If the design proves to be good I'll definitely upgrade opamps to MUSES01, I really want to hear the difference, if any. Next week I'll receive other missing parts so expect some updates then.
Br,
Aleš
thank you for the comment. What will the price be when it comes out, I do not know. Haven't done any calculations yet.
Yesterday I placed components on to the PCB and checked if regulators are working, no problem here. Delay is also working fine and it turns on after around 5 seconds. Opamps are now MUSES8920. If the design proves to be good I'll definitely upgrade opamps to MUSES01, I really want to hear the difference, if any. Next week I'll receive other missing parts so expect some updates then.
Br,
Aleš
Attachments
Thanks!Nice
At some point I really need to learn how to use eagle lol
I also hesitated for a long time with CAD software, but now I am so glad that I know how to use it. If only I'd learned it sooner
Finished - almost
I had time over the weekend so I assembled PCB and mount in the enclosure. DC offset is 0.2mV, well this shows my multimeter and it doesn't have the best mV range and accuracy. So DC servo is working as expected.
However I am facing some 50Hz hum issues, which I belive are comming from transformers. First I installed two EI-54 HAHN transformers and the hum was present at full volume on IEM headphones. Then I replaced these HAHNs with BLOCK transformer and the gain of hum was reduced, though still noticeable if I listened carefully. I also used this device as preamplifier and hum was audible if I placed my ear near to the speaker (distance 2-3cm). I doubt that it is ground loop as I have removed PCB from the enclosure and all connectors were placed on wood. Hum is the same if earth ground is connected or not. I have ordered two toroid transformers to see if there will be any improvement on hum issue. I will also try to build shield for transformers if there will be any improvement as they are quite close to the circuit.
Best Regards,
Aleš
I had time over the weekend so I assembled PCB and mount in the enclosure. DC offset is 0.2mV, well this shows my multimeter and it doesn't have the best mV range and accuracy. So DC servo is working as expected.
However I am facing some 50Hz hum issues, which I belive are comming from transformers. First I installed two EI-54 HAHN transformers and the hum was present at full volume on IEM headphones. Then I replaced these HAHNs with BLOCK transformer and the gain of hum was reduced, though still noticeable if I listened carefully. I also used this device as preamplifier and hum was audible if I placed my ear near to the speaker (distance 2-3cm). I doubt that it is ground loop as I have removed PCB from the enclosure and all connectors were placed on wood. Hum is the same if earth ground is connected or not. I have ordered two toroid transformers to see if there will be any improvement on hum issue. I will also try to build shield for transformers if there will be any improvement as they are quite close to the circuit.
Best Regards,
Aleš
Attachments
They are touching, but as I said in previous post, I removed the PCB from enclosure and I tried to move wire away from transformes as much as possible and it didn't help,
BR,
Aleš
I just did that. Removed transformers from PCB and used 15cm long wires to connect them back. Now I have no hum
. I also experimented which transformer is producing this noise and it appears to be the one next to the switch, interfering with left channel. Now I just need to build shiled around transformers. BR,
Aleš
Hi Aleš,
Something similar was discussed here: http://www.diyaudio.com/forums/chip...transformers-emi-electrostatic-shielding.html.
I am using GOSS on all my audio devices to shield the transformers; optionally I ground this shield. GOSS = grain oriented silicon sheet (https://en.wikipedia.org/wiki/Electrical_steel#Grain_orientation).
Also http://www.digikey.com/Web Export/S...former-pi-caging-transformer.pdf?redirected=1, G.O.S.S. Band - Custom Designed Toroidal Transformers from Nuvotem Talema and Introducing the Matrix M-Stage HPA-3U and HPA-3B, review to follow! - Page 4 might help in getting the idea about using this GOSS around transformers. I got the steel band from PETRA-toroid, but I've seen some "tones" on alibaba as well.
Perhaps a 1-2mm thick aluminum or copper sheet might be able to remove this noise or perhaps something from here Shielding Strips | RS Components, but in your case I would recommend GOSS (1 or 2 rounds of sheet), at least on the affected half of the transfrmer, the side that is facing the output buffer.
Regards,
Raul.
Something similar was discussed here: http://www.diyaudio.com/forums/chip...transformers-emi-electrostatic-shielding.html.
I am using GOSS on all my audio devices to shield the transformers; optionally I ground this shield. GOSS = grain oriented silicon sheet (https://en.wikipedia.org/wiki/Electrical_steel#Grain_orientation).
Also http://www.digikey.com/Web Export/S...former-pi-caging-transformer.pdf?redirected=1, G.O.S.S. Band - Custom Designed Toroidal Transformers from Nuvotem Talema and Introducing the Matrix M-Stage HPA-3U and HPA-3B, review to follow! - Page 4 might help in getting the idea about using this GOSS around transformers. I got the steel band from PETRA-toroid, but I've seen some "tones" on alibaba as well.
Perhaps a 1-2mm thick aluminum or copper sheet might be able to remove this noise or perhaps something from here Shielding Strips | RS Components, but in your case I would recommend GOSS (1 or 2 rounds of sheet), at least on the affected half of the transfrmer, the side that is facing the output buffer.
Regards,
Raul.
The Gauss band needs to be of iron.
I wonder if a couple of turns from a tin can would do the job?
A big paint can should give enough length for over two turns around a 30VA toroid. This is not connected to anything, no grounding lead.
One of my Sugdens uses a short length of steel pipe as a loose fit Gauss band. I think it had a gap from pipe to roroid of 5 to 10mm and was about 3 to 4mm thick. Just a bit taller than the toroid and secured to the chassis floor.
I wonder if a couple of turns from a tin can would do the job?
A big paint can should give enough length for over two turns around a 30VA toroid. This is not connected to anything, no grounding lead.
One of my Sugdens uses a short length of steel pipe as a loose fit Gauss band. I think it had a gap from pipe to roroid of 5 to 10mm and was about 3 to 4mm thick. Just a bit taller than the toroid and secured to the chassis floor.
Here's an expensive option...
http://www.amazon.com/Magnetic-shie..._cp_469_1?ie=UTF8&refRID=0ZE8M7DR3KFEZNZEKKGA
http://www.amazon.com/Magnetic-shie..._cp_469_1?ie=UTF8&refRID=0ZE8M7DR3KFEZNZEKKGA
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.