Input Needed For DIY Class A Amp!

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  • Systems
    Systems Posts: 14,873
    edited July 2009
    megasat16 wrote: »
    . Didn't you built the speaker protection circuits for the GC amps?
    No I don't use any outboard protection other than a big cap is series with my tweets when Im using active crossovers.


    I have decided to go with 2 of these boards from your pal Jim(odd name for a fella from HK me thinks):D
    http://cgi.ebay.ca/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWAX:IT&item=220412091344
    I will omit the opamp stage and just use the LM3886 sections which I will source from Digi Key so that I know they are not counterfits. I can get a pair of hefty 225VA TECA toroids on the cheap.I just have to decide whether to build a pair of stereo units or one 4 ch. unit
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  • megasat16
    megasat16 Posts: 3,521
    edited July 2009
    Thanks! I am covered for the heat sinks to test. I have plenty of large computer heatsinks used in the IT industry and they are more efficient (due to more fins to dissipate) for testing.

    But I think I am going to need some fancy looking heatsinks when mounting in the chassis. I am going to need a good case and a manly heatsinks like the ones from my ML...

    My pal Jim now seems to be your pal too. :D In the invoice I got from him, he said "Thank You Very Much, Dear Customer". :) Guess we are stimulating the Economy for the folks in HongKong. Nice people there. And Jim is pretty common name there too, coincidentally.
    Trying out Different Audio Cables is a Religious Affair. You don't discuss it with anyone. :redface::biggrin:
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  • megasat16
    megasat16 Posts: 3,521
    edited July 2009
    All parts and PCBs I bought from HongKong arrived today in the mail. The PCBs looks nice but the components are rather cheap Chinese Junks. I think I'll order in some good components and good caps separately. Photos coming up later too...
    Trying out Different Audio Cables is a Religious Affair. You don't discuss it with anyone. :redface::biggrin:
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  • Systems
    Systems Posts: 14,873
    edited July 2009
    megasat16 wrote: »
    The PCBs looks nice
    Great
    the components are rather cheap Chinese Junk.
    Yeah thats was my concern:(
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  • megasat16
    megasat16 Posts: 3,521
    edited July 2009
    GV#27 wrote: »
    Yeah thats was my concern:(

    The PCB is clean and well made. The parts for F5 are of mixed quality. F5 PCB has "PASS F5" on it like you said and not a good idea to have silkscreen with Pass Name on it like you said. :D

    Resistors are India made, and Small Transistors seems to be junks from China or India.

    Output MOSFETs seems to be genuine IRF stuff. I haven't taken out them from the static bag yet but they looks genuine IRF stuff.

    Caps came in the soft-start kits are real junks and seems recycled from somewhere. :eek:

    All other parts seems new and the relay is OK. A good Omron relay will cost over $20 on it's own so given the price of $13 kit, I can't complain much about it. :D It'll do the job for now. :D

    None of the kits / PCB has assembly manual, parts list, BOM, etc. included. Just Bare PCB or PCB with components but it's pretty simple to assemble.
    Trying out Different Audio Cables is a Religious Affair. You don't discuss it with anyone. :redface::biggrin:
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  • megasat16
    megasat16 Posts: 3,521
    edited July 2009
    I've assembled a few boards yesterday - mainly the softstart and the F5 boards.

    The only parts need to install on the F5 are output MOSFETs and JEFTs. I need to order in JFETs from reliable source such as DigiKey or Mouser. The ones came in the kits looks junks and I am afraid they'll take the other parts with them to Hell in a short while.

    I am also waiting for the Pure Copper Buss Bars (99.94%) to arrive for the capacitors bars in PS section. I need to buy more toroids and more caps. When will I have enough toroids? I have 2 toroids with twin 74VCT (for other Class A amp projects) and 2 toroids with twin 24VCT (for chipamp).

    Now, I am reading F5 design and it needs 24V rails so I need to find toroids with dual 18V outputs.

    Caps in stock are 63V 68000uF so they are not perfect for the F5 or Aleph 3 projects. I need to buy some cheap caps on ePrey also.

    I think I have enough HeatSinks for the F5, Aleph 3, and a couple of Chipamps.

    Pictures Below....

    I'll update on this again when I can put them together and test them.

    PS. A Word About Dayton 4% Silver Solder From Parts Express, It's NOT SUITABLE For Electronics Works such as this. I bought it at discounted price to try but found it's hard to work and it's melting point is actually higher than other normal solders. Also, the finished color of it makes me think whether it has any silver in it at all. The solder puddle when melted is also not very sticky to the metal surface so you need more of it than regular solder. Kester or Other Regular Solder is easier to work with....I'll not BUY Dayton Silver Solder again for Electronics Projects. But if you are making cables and such, it may be OK.
    Trying out Different Audio Cables is a Religious Affair. You don't discuss it with anyone. :redface::biggrin:
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  • Systems
    Systems Posts: 14,873
    edited July 2009
    I'm drooling.:D Good to hear the IRF's look legit.,besure to handle with care.The Jfets might be hard to source Mouser might stock them but I don't think Digikey does.I can't remember the name of the company ( I will try to find it)that for sure does sell them in the US.


    Where did you source those heatsinks?
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  • megasat16
    megasat16 Posts: 3,521
    edited July 2009
    Thanks GV! :D

    Yep! I have to be careful with these MOSFETs. But I am going to order a few too in case I need to match them. The MOSFETs in the kit are IRF240 and IRD9240 (2 each type).

    I have to look around the JFETs and other parts a bit later as I have other things in the next couple of days.

    I bought these Heatsinks on eBay (new old stuff) for 10 at $49 and shipping is like $18. They are like 6lbs each and has a few pre-drilled holes. I need to come up with a good idea how to mount them in the chassis.

    I am thinking they will be on top cover (made of copper sheet) since the shape of heatsinks and the fins suggest it'll be ideal to mount on top for better heat dissipation.
    Trying out Different Audio Cables is a Religious Affair. You don't discuss it with anyone. :redface::biggrin:
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  • megasat16
    megasat16 Posts: 3,521
    edited July 2009
    Correction : HeatSinks are 2.75lbs each. I have mistakenly stated them at 6lbs each. No doubt parts of my brain cells are dead or not functioning.

    The seller seems to have 6 more left. The HeatSinks are black anodized and polished. But he didn't ship them in well packed package so 4 out of 10 them have minor abrasions when I received them.


    http://cgi.ebay.com/SIX-6-CLEAN-HEATSINK-ALUMINUM-EXTRUSION-LARGE-BLACK_W0QQitemZ220452269107QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item3353faac33&_trksid=p3911.c0.m14&_trkparms=65%3A12|66%3A1|39%3A1|72%3A1205|293%3A1|294%3A25
    Trying out Different Audio Cables is a Religious Affair. You don't discuss it with anyone. :redface::biggrin:
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  • heiney9
    heiney9 Posts: 25,384
    edited July 2009
    The real trick to re-creating a true First Watt F5 is in the matching of the inputs and outputs. Each is matched within the circuit. For a DIYer probably not feasable as you'd have to buy a large amount and then experiment with them in the circuit.

    Looks like a LOT of FUN. Hope it is a successful end result for you. :). Keep us posted. I have put off my build for the time being as I just don't seem to have enough time lately. But, I am going to build a nice gainclone very soon.

    H9
    "Appreciation of audio is a completely subjective human experience. Measurements can provide a measure of insight, but are no substitute for human judgment. Why are we looking to reduce a subjective experience to objective criteria anyway? The subtleties of music and audio reproduction are for those who appreciate it. Differentiation by numbers is for those who do not".--Nelson Pass Pass Labs XA25 | EE Avant Pre | EE Mini Max Supreme DAC | MIT Shotgun S1 | Puritan Audio PSM136 Pwr Condtioner & Classic PC's | Legend L600 | Roon Nucleus 1 w/LPS - Tubes add soul!
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  • Systems
    Systems Posts: 14,873
    edited July 2009
    Matching is not critical with the F5 as there are no differential pairs at the input or paralleled MOSFET's in the output stage.It is important to use the BL grade for the input Jfet's.Here are two possible sources for the hard to get Toshiba SK170,370,J74,J108's.
    http://www.tech-diy.com/Store/SmallSignal.htm
    http://www.ampslab.com/components_fets.htm
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  • megasat16
    megasat16 Posts: 3,521
    edited July 2009
    GV#27 wrote: »
    Matching is not critical with the F5 as there are no differential pairs at the input or paralleled MOSFET's in the output stage.It is important to use the BL grade for the input Jfet's.Here are two possible sources for the hard to get Toshiba SK170,370,J74,J108's.
    http://www.tech-diy.com/Store/SmallSignal.htm
    http://www.ampslab.com/components_fets.htm

    Thanks for the linky! Now, you said about these JEFTs, I am thinking NP may actually be living in Japan instead of the U.S since he is using these Toshiba. :D

    I looked at the ones that came in the kit and they are exactly the same looking ones as in the AmpLab.com pictures. So, I think I may be just using them and cross my fingers when testing the finished board. :)

    I think matching for complimentary pairs of N and P channel MOSFETs are still highly desirable if there is a mean to it. But it seems I may need to buy a bulks of the output MOSFETs to find a few good matched pair.



    H9, I have a good transistor tester to match the Power (or small) Trannies. It's a MUST HAVE tool for me. :D
    Trying out Different Audio Cables is a Religious Affair. You don't discuss it with anyone. :redface::biggrin:
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  • megasat16
    megasat16 Posts: 3,521
    edited July 2009
    The JEETs came with the kit are 2SJ103 (p Channel FET) and 2SK246 (n Channel FET) instead of the 2SJ74 and 2SK170 as in the original design. I looked at the data sheets on ampslabs and they seems to be cheaper alternative (but not low noise version). They may take a toll on the sound quality. I don't know yet.
    Trying out Different Audio Cables is a Religious Affair. You don't discuss it with anyone. :redface::biggrin:
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  • Systems
    Systems Posts: 14,873
    edited July 2009
    megasat16 wrote: »
    Thanks for the linky!
    Your welcome
    Now, you said about these JEFTs, I am thinking NP may actually be living in Japan instead of the U.S since he is using these Toshiba. :D
    You would almost think so:D.Unfortunately Tosh has a bad habit of discontinuing (or atleast making them hard to get)excellent semiconductors.
    I looked at the ones that came in the kit and they are exactly the same looking ones as in the AmpLab.com pictures.
    Great you should be good to go.
    I think matching for complimentary pairs of N and P channel MOSFETs are still highly desirable if there is a mean to it. But it seems I may need to buy a bulks of the output MOSFETs to find a few good matched pair.
    Yeah It might take a few to get a good matching pair.Many are building F5's sucessfully without matching however.On the other hand with the Aleph 3 you will want to match the differential pair of mosfets at the input and the two paralelled outputs.
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  • megasat16
    megasat16 Posts: 3,521
    edited July 2009
    GV#27 wrote: »
    You would almost think so:D.Unfortunately Tosh has a bad habit of discontinuing (or atleast making them hard to get)excellent semiconductors.

    Bad Tosh...Bad Bad Bad Tosh...It's a miracle they are still in this Semiconductor Biz. :D
    GV#27 wrote: »
    Great you should be good to go.

    I need to find the right toroidals for the F5. I could use bench power supply to test the board but I am not confident to run it for long.
    GV#27 wrote: »
    Yeah It might take a few to get a good matching pair.Many are building F5's sucessfully without matching however.On the other hand with the Aleph 3 you will want to match the differential pair of mosfets at the input and the two paralelled outputs.

    Yep! I probably should buy the MOSFETs from the shop who will sell me matched pairs. I am wondering anyone sells matched MOSFETs for Aleph 3. I need to buy all components for the Aleph 3 since I only bought PCB for it from your pal Jim. :D
    Trying out Different Audio Cables is a Religious Affair. You don't discuss it with anyone. :redface::biggrin:
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  • Systems
    Systems Posts: 14,873
    edited July 2009
    megasat16 wrote: »
    I need to find the right toroidals for the F5.
    Yeah you'll need a high current 2x18VAC.I will be on the look out for you.


    I am wondering anyone sells matched MOSFETs for Aleph 3.
    http://www.tech-diy.com/Store/Hexfets.htm
    from your pal Jim. :D
    He won't be my pal unless I buy a few PC boards from him.:D
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  • megasat16
    megasat16 Posts: 3,521
    edited July 2009
    GV#27 wrote: »
    Yeah you'll need a high current 2x18VAC.I will be on the look out for you.

    Thanks! I found a 400W Toroid on eBay for $40 each and shipping is $10 (so, $45 including shipping). So, they'll be the most expensive toroids I have purchased to date.
    GV#27 wrote: »
    http://www.tech-diy.com/Store/Hexfets.htm
    He won't be my pal unless I buy a few PC boards from him.:D

    I thought you already bought a few PC boards for Aleph 3. What are you waiting for? :D

    The matched MOSFETs offered on Tech-DIY are IRFP240PbF but the ones for the Aleph 3 are IRF244 (IRFP244). I read the data sheets and there are a few differences between these two and the IRFP240 has lower voltage rating but more current capacity at 20A. I think it should be OK though.
    Trying out Different Audio Cables is a Religious Affair. You don't discuss it with anyone. :redface::biggrin:
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  • Face
    Face Posts: 14,340
    edited July 2009
    Beware of cheap toroids, some hum like a SOB.
    "He who fights with monsters should look to it that he himself does not become a monster. And when you gaze long into an abyss the abyss also gazes into you." Friedrich Nietzsche
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  • megasat16
    megasat16 Posts: 3,521
    edited July 2009
    Face wrote: »
    Beware of cheap toroids, some hum like a SOB.

    Yep! It's usually is a problem for Tube Amps where it is directly coupled to the Tubes. That's why you want the best possible Transformer for Tube Amps.

    For SS amps, the hums is usually not heard since most of them gets filtered by the Caps banks. I think all transformers have mechanical hums (more or less audible) due to the load stress. Some being worse than others due to the el cheapo core and copper wires.

    This is the one I get. I think it's better made than the cheap toroids offered from PE.

    http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=370229745818
    Trying out Different Audio Cables is a Religious Affair. You don't discuss it with anyone. :redface::biggrin:
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  • Face
    Face Posts: 14,340
    edited July 2009
    That's not always true about SS. I heard a F5 clone that was so loud, it could be heard from 10' away.
    "He who fights with monsters should look to it that he himself does not become a monster. And when you gaze long into an abyss the abyss also gazes into you." Friedrich Nietzsche
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  • megasat16
    megasat16 Posts: 3,521
    edited July 2009
    Is that a Mechanical Hum? I think the transformer may be seriously under powered and the caps bank may be stressing the transformer. I hope it's not going to happen with mine.
    Trying out Different Audio Cables is a Religious Affair. You don't discuss it with anyone. :redface::biggrin:
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  • Systems
    Systems Posts: 14,873
    edited July 2009
    Poorly wound toroids can buzz like a bugger.Also there is a possibility of small levels of DC being carried on the AC that can reach the primary of a good toroid and make it buzz.There is an easy fix for this but your SOL with a bad winding.
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  • Systems
    Systems Posts: 14,873
    edited July 2009
    megasat16 wrote: »
    I thought you already bought a few PC boards for Aleph 3. What are you waiting for? :D
    Indecision:confused: I will be ordering a pair of the dual LM3886 boards from jimmy.
    Also if I can find an appropriate chassis I will build either an A3 or F5.I didn't end up buying the F5 boards from Peter Daniels.
    The matched MOSFETs offered on Tech-DIY are IRFP240PbF but the ones for the Aleph 3 are IRF244 (IRFP244). I read the data sheets and there are a few differences between these two and the IRFP240 has lower voltage rating but more current capacity at 20A. I think it should be OK though.
    As long as the voltage and current ratings are appropriate there is a lot of interchangablity with the IRF and Fairchild Mosfets.
    If you want to buy a few and match them yourself it isn't very hard,and matching like devices(Pchannel-P channel) should be easier than P-N.


    this might be useful.http://www.passdiy.com/pdf/matching.pdf
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  • megasat16
    megasat16 Posts: 3,521
    edited July 2009
    GV#27 wrote: »
    Indecision:confused: I will be ordering a pair of the dual LM3886 boards from jimmy.
    Also if I can find an appropriate chassis I will build either an A3 or F5.I didn't end up buying the F5 boards from Peter Daniels.

    I found all confusion and indecision came to an end when I am drunk...So, I suggest you stock up on more beers....:p :D
    GV#27 wrote: »
    As long as the voltage and current ratings are appropriate there is a lot of interchangablity with the IRF and Fairchild Mosfets.
    If you want to buy a few and match them yourself it isn't very hard,and matching like devices(Pchannel-P channel) should be easier than P-N.


    this might be useful.http://www.passdiy.com/pdf/matching.pdf

    I don't want to buy a bulk of MOSFETs and test for myself. I've heard the chance of getting matched pairs are about 30%-50% out of 100 MOSFETs from the same batch. But I don't know what to do with the leftover MOSFETs so I will just order two sets of matched Quad IRFP240 from diy-tech. It should be OK since the maximum voltage swing in Aleph 3 is less than 50V.

    Tech DIY store has matched triplet of IRF9610 too. I only need to order caps and resistors from mouser or digikey for Aleph 3 projects. I'll need to look for a good chassis later too.
    Trying out Different Audio Cables is a Religious Affair. You don't discuss it with anyone. :redface::biggrin:
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  • Systems
    Systems Posts: 14,873
    edited July 2009
    megasat16 wrote: »
    I found all confusion and indecision came to an end when I am drunk...So, I suggest you stock up on more beers....:p :D
    Hummm that might help,but it could also get me into trouble.:D

    so I will just order two sets of matched Quad IRFP240 from diy-tech.
    Yeah that would likely be your best bet.
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  • megasat16
    megasat16 Posts: 3,521
    edited July 2009
    GV#27 wrote: »

    this might be useful.http://www.passdiy.com/pdf/matching.pdf

    I've printed it out and will be reading it over the weekend.
    GV#27 wrote: »
    Hummm that might help,but it could also get me into trouble.:D

    I thought you are old enough not to get into troubles. :D
    Trying out Different Audio Cables is a Religious Affair. You don't discuss it with anyone. :redface::biggrin:
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  • Systems
    Systems Posts: 14,873
    edited July 2009
    megasat16 wrote: »
    I'll need to look for a good chassis later too.
    Yeah they are hard to find.Hammond makes a number of boxes suitable for GC's but the heatsinking and PS's requirements for the class A stuff needs something abit more substantial.Maybe one could find a suitable junker at a local stereo/ hi end service shop on the cheap.There are a few Asian suppliers but I don't have any linky's as of yet to see what they have available.
    I thought you are old enough not to get into troubles. :D
    Not yet.:D
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  • megasat16
    megasat16 Posts: 3,521
    edited July 2009
    The two toroids I bought from Antek has arrived in the mail today. So, I'll be smoking up some stuff (components) over the weekend. :D

    Hopefully, no white smoke or black burns or FIRE. :eek:

    When the smoke is clear, I'll have to think about the chassis. May be plexi for the sides and front and back, and some aluminum for the top and bottom.


    GV#27 wrote: »
    Yeah they are hard to find.Hammond makes a number of boxes suitable for GC's but the heatsinking and PS's requirements for the class A stuff needs something abit more substantial.Maybe one could find a suitable junker at a local stereo/ hi end service shop on the cheap.There are a few Asian suppliers but I don't have any linky's as of yet to see what they have available.
    Trying out Different Audio Cables is a Religious Affair. You don't discuss it with anyone. :redface::biggrin:
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  • genroxbro
    genroxbro Posts: 6
    edited July 2009
    INA217 is TIs top range instrumentation amp for audio. THAT feels they have a better product, there is also AD in that game. Its a bit of a Ford vs. Chevy argument. THAT does have better efficiency which is always a plus in my book.
    _____________________________________
    Website I designed for payday loans on line company.
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  • megasat16
    megasat16 Posts: 3,521
    edited July 2009
    genroxbro wrote: »
    INA217 is TIs top range instrumentation amp for audio. THAT feels they have a better product, there is also AD in that game. Its a bit of a Ford vs. Chevy argument. THAT does have better efficiency which is always a plus in my book.
    _____________________________________
    Website I designed for payday loans on line company.

    You are advertising your **** Payday Loans Company in your Sig! You are REPORTED.
    Trying out Different Audio Cables is a Religious Affair. You don't discuss it with anyone. :redface::biggrin:
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