My_Ref Fremen Edition RC - Build thread

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Cool Amp (BLAT)

Finally completed all major aspects of the liquid cooled build. I'm taking a sabbatical at this point because I can't stand to even look at a drill, tap or file any more. :eek:

The format here was to make two self-contained packages with provisions that any possible leaks will flow away from the amp. That was accomplished with the realization that an airtight system will negate the gravity effect of a liquid, allowing the reservoir to be located anywhere.

I took lots of pictures and will post a separate complete build thread in a few days. Till then here are a few pics of the result.

All the signal in and out wires are of equal length. These are the 120VA toroids from ApexJr powering the FE beta builds. Didn't have the courage to tap the FEs for 12 VDC for the pump and fans so I installed a socket for a regular wall wart for now.

In the third photo the complete cooling system is visible with all components below the top of the aluminum base. For those of you who may be less adventurous (read - old fuddy duddies) I did make a mounting hole matched conventional cooling module that replaces both the plates and heat sinks.

Made a pasteboard template of a possible cover that I'll transfer to metal eventually. It will most likely have a panel that covers the heat sinks completely. Been hanging on to the two Zebrawood burls for twenty years - this may be where they end up.

The FEs are working great with DC readings ~ 12 - 15 mV. The output is clear with no hum or distortion - though Marra did put the hex on me and one LED stays off. :mad: The speaker posts will accept spades or bare ends and will work just as good if not better than bananas.

Been a fun project and I post some temp data on the build thread.
 

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I am going to be more than a little cynical and ask if you have performed the ultimate test of a multi-channel power amp?

Have your connected up all the interconnects to all the available inputs and commoned all the remote end barrels (signal grounds)? And then measured the hum at the output.

I do agree, that is some achievement in packaging !
 
Marra, thanks. You got me. :D

Have you got any good news? It sounded like you were just about there a few posts ago.

Andrew, I'll get back to your qusetion in a few minutes after I switch things around. For testing I used my normal DIY 3" bench speakers and a Walkman as a source. I configure a full system and report back.
 
Andrew, can you hear that??

It's golden FE nectar with just a touch of Sunflower juice. :D

The system sounds perfect so far - no hum no distortion. However there was a got-cha that I must divulge. Since this is my first chipamp build :rolleyes: , in my haste I didn't apply new paste on the chip and check the mounting bolt for tightness on one module. The result was of course a protection trip. Easy to fix but I blaming it on you.:p

So far so good. I'll use the new setup for the rest of the day and report back.

Mini 2496 - BNC feed
DIY silver interconnects
DIY Cat 6 speaker cables
Sunflower Speakers.
 

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Bob,

It looks really great. My questions are about the cooling fluid. Is the reservoir in the bottom or not in the pictures? Also, how do you connect to the heat exchangers. It kind of looks like safety wire around a hose, but I can't see clearly.

It is a very interesting concept. I wish there was a good way to measure distortion or something on your units. I can imagine we would all learn something if you could vary the flow so that the chip amp temp could be held at different temps while under the same electrical condition. It would be neat to understand how much temperature affects the output. I mean more than what we get from the data sheet. That, combined with hearing any difference would be cool.

Jac
 
Hey Jac,

You are right on target with your questions. You will get some answers from the build thread - hopefully by tomorrow evening.

One of the reasons I didn't tap DC from the FE is the probability that a rheostat will be needed to control the flow. That's not something I want to expose the amps to.

I'm still digging into the Visual Analyzer software in hopes I can provide the data you mention. There are a couple other programs that might work but aren't quite as extensive.

I have only one real world experience. Several weeks ago on the intermediate build, I forgot to turn on the pump/fans. After 30-40 minutes the protection started to cause dropouts and fuzzy sound. Within a minute or so it all went away. That just shows the cooler works but doesn't prove this is necessarily any better/different than standard air flow cooling.

P.S. Received the caps package today and am looking forward to hearing the K71s this weekend. Thanks.
 
Bob, nice work! My congrats!;)

Great! :)
I'll wait your listening impressions...

I'll let FE burn in for a week or so and then make a thorough comparison.

Yesterday I compared bass representation on both channels:
1. cheap cement 0R47 + Vishay 1% 50ppm smd resistors (0.1% Panasonics I didn't touch on both channels)
2. Pair of DALE 1R in parallel + Tackmans instead of smd resistors (mistakenly bought by me)

So it was performed only on the speaker that has a bass issue as I reported earlier (turned out to be just a speaker placement). No difference was found here, bass seemed to me equal on both channels.
I know that is not a proper way of testing, though it convinced me staying with Tackmans and DALEs :rolleyes: So I updated the 2nd board and am happy with that!
 
so I made a brief comparison (about an hour) of FE and my modded Restek (caps, opams, bias, wires changed). Interconnects are pure silver twisted pair, speaker cable - Kimber 8TC, CD - modded Philips 350 (has been upgraded heavily, though I suspect Philips to be the weak link here). As a pre I used 10k Alps blue pot, nothing more, I decided to omit my active pre based on LM49710HAs as it seems to me very detailed, though a bit specific in bass reproduction.

So it was only:
Matallica - My World
Apocalyptica - World Collide
Godsmack - I am

I didn't include the rest of my collection (it's basically more heavy than these 3 CD, like Slayer, Slipknot and so on) as these tracks I know for a decade for sure.

FE
- clean, detailed, great soundstage (like more then on Restek), immediate and precise bass, very powerful (didn't even expect it to be so).

Restek
- extremely dynamic, detailed, deep bass and I would say born to play heavy metal.

So in a few words, FE was very close to my reference amp and even greater in some aspects and as a result I was very surprised with that! didn't even expect it to be so! wow! diy chip amp and hell it's so superb! Although for metal and heavy music I'd prefer my Restek, I would be very delighted to use FE as well.

More serious test would be held in a few weeks time, once I get a new laser for my Primare CD, old is dead :) and when FE will be fully burned in.
 
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So in a few words, FE was very close to my reference amp and even greater in some aspects and as a result I was very surprised with that! didn't even expect it to be so! wow! diy chip amp and hell it's so superb! Although for metal and heavy music I'd prefer my Restek, I would be very delighted to use FE as well.

I'm happy you're enjoying the FEs :)

But since I've tried Takmans I suspect you can have better detail and dynamics using Susumus.... ;)
 
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No music I'm afraid :( Before connecting to my system I decided to check things one last time;connected up the speaker outputs and the phono sockets and switched on.Both pcb's had the right voltages;low offset although the iffy one was fluctuating from 4mv to 4.6mv.I left it on whist having my tea then checked the readings again.Whilst doing this on the faulty one the relay clicked off and stayed off.The voltage between R14 and centre ground was 31v at both ends of the resistor with no reading across the relay diode.On the other board the voltage at R14 is 22.39v with 15.45v across the diode.
Frustration reigns :mad:
 
Is that repeatable - meaning if you leave the power off for a long time does the cycle start over again?

I know you don't want to do it, but I'm still curious about what swapping the relays would do. If you use solder removal braid they almost fall out on their own. It may not be the answer but it appears you have tried most other options. Maybe Dario will concur. I did have a faulty relay on a TP v1.2 build.
 
Everything appears secure Bob.Just realised that I had forgotten to say that the heatsink remained stone cold whereas on the ok one it warm up a little also that the relay on the faulty channel clicked on and off approx 10 seconds after powering down.

This happened to me too. It will be on and off for few seconds. And then switch off. When I switch off the power, LED will glow for 2 sec. And then I tried without speaker out. Its okay. Then I tried the speakers connecting straight away to the board. It worked fine. Later I realised I may be sorting something in speaker binding post.

Thanks
Badri
 
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