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Chip Amps Amplifiers based on integrated circuits

My_Ref Fremen Edition - Build thread and tutorial
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Old 6th November 2017, 07:18 PM   #3591
jwjarch is offline jwjarch  United States
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Wired up one of my toroids for a quick test on one board last night. Relay clicked on the first power-up! I guess my soldering skills aren't so bad after all. Also, I was reading .01mV offset on the output. I'm VERY happy with that. Other voltage readings were pretty much on spec except for R101, which is only reading 1.1V. R201 is reading 1.2V. Is this an issue? Also, ground to the LM317 is reading a few volts below 35V, but I would assume this is attributable to the fact that I am using an Antek AS-2222 with 22V secondaries. Let me know if anyone has any thoughts on my voltage measurements. I haven't hooked the amp up to a source or speaker yet.
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Old 6th November 2017, 09:15 PM   #3592
lehmanhill is offline lehmanhill  United States
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Quote:
Originally Posted by jwjarch View Post
Wired up one of my toroids for a quick test on one board last night. Relay clicked on the first power-up! I guess my soldering skills aren't so bad after all. Also, I was reading .01mV offset on the output. I'm VERY happy with that. Other voltage readings were pretty much on spec except for R101, which is only reading 1.1V. R201 is reading 1.2V. Is this an issue? Also, ground to the LM317 is reading a few volts below 35V, but I would assume this is attributable to the fact that I am using an Antek AS-2222 with 22V secondaries. Let me know if anyone has any thoughts on my voltage measurements. I haven't hooked the amp up to a source or speaker yet.
Congratulations! No smoke and a relay click.

Regarding the voltage across R101, I would check the voltage across C102 and C202. They should be within 1 volt of the +14V/-14V respectively. Also flip over to ACV at the same time and make sure there is very low AC. The difference you are seeing is probably nothing, just component variation in the regulator circuit.

When you are talking about ground to LM317, I assume you mean the voltage across C101 and C202. If that's the case, then yes, with the 22 VAC secondaries and no load, you will probably be around 30V. It will likely drop a bit when you start running current through the amp.

If I were in your shoes, I would wire up an expendable speaker, feed the thing with some sort of volume control of pre-amp, and see if music comes out.

Jac

Last edited by lehmanhill; 6th November 2017 at 09:17 PM.
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Old 7th November 2017, 06:36 AM   #3593
jwjarch is offline jwjarch  United States
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Thanks for the tip Jac. I tested both boards with a makeshift speaker (Dayton PS95-8) and my phone as the source. They sound fantastic!!! Can't wait to get them playing through some real speakers. Thank you Dario and everyone that contributed to the My_Ref, especially the late Mauro Penasa.
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Old 7th November 2017, 02:07 PM   #3594
lehmanhill is offline lehmanhill  United States
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YAHOO!!
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Old 9th November 2017, 08:30 PM   #3595
jwjarch is offline jwjarch  United States
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A few updates. I'm working on mounting all of the components for the cleanest look possible. Here's why I soldered the Faston terminals to the bottom of the board. I wanted the look of a tube amp's exposed components without all the wire clutter. I'm really happy with the way its coming together so far. All the wires will be concealed below the 1/8" thick aluminum plate. I'll build a wooden frame for the aluminum plate to sit on and recess the input rca's, mains plug, and speaker output terminals into the wood frame.


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Old 10th November 2017, 08:57 AM   #3596
AndrewT is online now AndrewT  Scotland
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Please attach sensible size images.
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regards Andrew T.
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Old 10th November 2017, 01:36 PM   #3597
rough512 is offline rough512  Philippines
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I also thought of running the output wires under the boards, but it's difficult manipulating my planned solid wires. I ended up with this. Signal wites between preamp and muref are ran underneath.
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Old 5th December 2017, 09:44 PM   #3598
mparshall is offline mparshall  United States
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Apologies for busting in here, but was hoping you guys might be able to get me back on track...

I ordered qty6 1.7 boards back at the initial group order. At the time I had been following the 1.7 build thread enthusiastically and especially the various componant swaps/trials.

At some point (c Sep 2016) I kind of dropped off the face of the earth, and am now back and interested in sourcing parts and building 6 channels. I plan to follow through the build thread for 1.7 from where I left off, but am really interested in the current evolution of ultimate parts BOM for 1.7 and where to find it.

Again, sorry if I posted this in a < appropriate place (and long in content)

Everyone have a great and festive Holiday season, and stay safe!

Mark Parshall
from SFO bay area, USA
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Old 6th December 2017, 12:54 AM   #3599
lehmanhill is offline lehmanhill  United States
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Hey Mark,

Welcome back. Don't feel you are behind the times. I'm about to start building some v1.2 boards I have and will eventually get around to the V1.0. The cool thing is that the circuit hasn't changed, just better implemented and updated BOM.

For a normal build, the Google Drive folder on the first post of this thread takes you to the BOM, etc. The first link has the BOM for version 1.5 and up. The suggested best part columns are what you are looking for.

There are some tweaks. The evo A is a worthwhile tweak and is also shown in the BOM. IF you are confident of your skills and want to try the latest ideas, start reading at about post 3078, page 308. Joseph K has been experimenting with opamps and has found interesting options. Care is needed at each step because you could ruin your amp or speakers, but everyone who has tried them has liked them.

Good luck and enjoy.

Jac
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Old 9th December 2017, 07:34 PM   #3600
mparshall is offline mparshall  United States
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Jac,

Thanks for the great recap and suggestions. That is exactly what I needed. I am getting my 29year old Son interested in diy audio electronics and speaker design. Slightly advanced place for him to start, I know...

Cheers,
Mark
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