| Peter Daniel |
| I have finally finished my first Aleph! It's has a voltage and configuration of Aleph 5 but is done as monoblocks and the bias is lower because the heat sinks are too small. It's already has a nickname of a "Toaster Amp" but for me it might well be the cutest amp I've built so far. The hole chassis is alodined and that's where the gold shine comes from. Top and bottom is done from fibre-like material. Binding posts are modified Music Posts. |
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| Peter Daniel |
| As usually I decided to wire everything. The input board is mounted on front panel and is attached through the binding posts nuts. I used a small heat sink for all 3 mosfets. PS caps are glued with red RTV to the bottom plate and transformer is mounted on one of the heat sinks. Transformer is shielded with copper. I'm using 120u Panasonic HFQ caps for bypass and 2 separate bridges for +/- rails. I made those legs out of 3/4" aluminum rod. |
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| Peter Daniel |
| This is how front end is wired. That circuit is so simple that no board is really required. I had some problems with running second channel and I suspected damaged mosfet in that circuit. Took me really quick to replace all 3 mosfets and I was back in business. As you can see I'm using fibre plate to separate the heat sink from the chassis, that plate also acts as an insulator for binding posts nuts. After I decided on the layout, putting that circuit together was like putting together PCB. The only hard part is to take measurements when testing amp, the access with probes is really hard. There is a nice bus bar in the center made out of Goertz flat wire. It is for the output and source resistors and drains of output devices are connected there. From here, Caddock 0.1 resistor connects to the output post. |
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| Peter Daniel |
And this is how it looks from the top. I didn't use any compensating caps, not even 10p. I tested first chanel on the scope and it looked clean, second one has some small spikes below 80Hz.
As to the sound, I can only compare it to A75 which I have been using for last 7 years. In my current bi-amp setup I'm also using that amp as midrange and tweeter amp so I won't comment on bass control. But after replacing A75 with Aleph I wouldn't go back. The tonal character is similar but Aleph presents sort of liquidity and easiness to the sound, making it more natural. It also seems like more notes is coming out of speakers. The soundstage might be slightly bigger but not by much. A75 is more SS sounding. |
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| Apogee |
Very Cool!!!
Great job....toasters or not, I like em.....
Steve |
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| trigon |
Exelent job Piter. BRAVO.
Thats what I'm talking about. :cool: |
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| ebrewste |
| Out of curiosity, how did you end up with an alodined chassis? |
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| Peter Daniel |
I bought the heat sinks surpluss. They were alodined originally. I got 1/4" aluminum material for front and rear plates at surplus and it was kinda gold as well. Because it was scratched in some spots I tried to brushed it of with Scotch Brite. And then the problem started, because I brushed off the gold finish that matched the heat sinks. I didn't know what to do about it, so I realized I had some alodine left from my work with aircrafts and since I knew it makes aluminum gold I brushed off the rest of the finish from plates and put them in alodine bath. After couple of minutes they were gold again and looked like before.
So I came with that idea that alodine might be a cheap alternative to anodizing, of course if you don't mind the gold finish. It protects against corosion and finger marks. On my amp when combined with dark brown top cover that finish looks really cool.:cool: |
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| Peter Daniel |
| Thank you.:) |
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| trigon |
What kind of insulators are you using for your mosfets???
Never seen something like that. Or is it just picture maybe???
Thanks. :confused: |
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| mpopovics |
Congratulations! It looks excellent.
The monoblock was very good idea.
Was it difficult to solder the second heatsink FETs to the board?
BR,:) |
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| leroy |
| quote: | | What kind of insulators are you using for your mosfets??? |
Those are aluminium-oxide (Al2O3) insulators. The thickness is an advantage since the capacitive coupling between output devices and heatsink is reduced.
leroy |
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| Peter Daniel |
I used berilium oxide insulators. Presumably they have a toxic nature and should be handled properly. However, they are probably the best.
Soldering the mosfets on second heatsink wasn't really a problem, just 7 joints. I had to use 80W solder gun for that purpose. |
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| jam |
Peter,
Have you tried increasing the current through the gain stage of the A75 or even increasing the bias of the output stage and comparing the results?
Jam
P.S. Sonically I got the same results when I did the comparison of the two amplifiers. The A75 seems to have better bass though. |
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| Peter Daniel |
| quote: | Originally posted by jam
Peter,
Sonically I got the same results when I did the comparison of the two amplifiers. The A75 seems to have better bass though. |
That's why it's going to stay in my system as subwoofer's amp.
I didn't increase the bias on A75, actually for subs amp I reduced it to generate less heat.;)
Still I think that because of simplicity the Aleph would always sound better. I'm hearing sounds I did not hear before and I thought A75 had really good resolution. There is something 3-dimentional about Aleph's sound, and I'm not talking here about soundstage only. It's more about how it presents different musical notes (I'm not sure if I'm using correct words here). Maybe Mr. Pass was correct after all about the single ended character of the air?;) |
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| oliverniekamp |
| Your aleph looks great, better than mine. I made it as an aleph 3 and changed the output stage to aleph 30 last year. I always do ptp on a board, its a real fun for me. Dont worry to much if your aleph is getting hot ,mine is to hot to touch and it didnt break the last two years. |
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| CDale |
HPotter,
A little bit off topic, but did you source your surplus heatsinks in Toronto. If so, I would be interested in knowing where.
Thanks,
CD |
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| Lisandro_P |
| Looks great, congratulations! |
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| Peter Daniel |
| I used to find surplus heat sinks at Active Surplus or Sayal but it's hard to find them there this days. Other source I know of is R-theta. I bought heat sinks for my A75 there. They were located in Mississauga. |
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| BrianGT |
Peter,
What did you do to modify your Music Posts?
--
Brian |
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| HarryHaller |
Looks like extended hex nuts instead of knurled round "nuts" with blade screw driver slot. Tight fit but easier to torque down.
H.H. |
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| Peter Daniel |
Actually I had to do it. I bought rejects from Sonic Frontiers long time ago. I think I paid $5 for a set. They were selling them without original nuts and on some of them the plastic part was deformed because someone used too much heat when soldering. I bought brass nuts at Home Depot, retapped them and polished. They look even better than originals. :cool:
BTW I think Music Posts are the most affordable quality posts. |
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| fcel |
Peter,
How do you cut square/rectangular holes for the AC jacks/switch? I've got a response from Brian before but let's hear from you too. Type of tools and may be a picture of the tools that you used - I've seen you done that before. Thanks. |
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| grataku |
HPotter,
have you found problems in having the transformer so close to the circuit? Is there really any advantage in having the Cu shield around the transformer or is just there for good practice? |
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| Peter Daniel |
| I don't know if it's because of the transformer but I have a bit of hum which disappears after the amp is warm. The shield is there for good practice. |
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| Rarkov |
How is the transformer held to the heatsink? I'm assuming you don't have a great dirty bolt going though it...
What's the secret? Is it to do with all the black stuff in the middle?
Edit:
I forgot to ask...I'm building a low power Aleph X in a very similar design...It'll have 4 fets per channel and a low voltage (need to recalculate - but around 14V). Would this compact design take the heat etc?
Cheers,
Gaz |
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| Peter Daniel |
| I potted aluminum bar through the middle, and use a smaller bolt to hold it to the heatsink. I have to turn the transformer to screw it in. I don't know if I would do the same today. |
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| Rarkov |
What would you do to hold a 500VA xfomer to a heatsink without drilling through the heatsink? Seems like a nice challenge for you! ;)
Gaz |
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| Peter Daniel |
| You might use silicone or some glue, but it's risky. If the space is tight betwen two walls you might use expandable foam to feel everything, les vibrations transferred too;) |
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| Rarkov |
No - That doesn't appeal - but I do have a good idea. I will rest it on the floor of the amp (in the same orientation as you) and make a bracket from thin al that will hold it in place.
I prefer metal to glue! :goodbad:
Cheers...
Gaz |
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| wuffwaff |
Nice looking amps Peter!
Just wait a few months and they`ll get better and better:) :)
Still canīt believe how my 5 sounds after running in properly.
william |
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| PedroPO |
Very good! indeed!
Finally it is ready.
I think I saw those chassis first time last year!!!
keep up with the good work;) |
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| Peter Daniel |
| I finished them a year ago;) |
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| PedroPO |
ummm...
yup! should read the dates also...... lol!!!!
I knew Id seen them before :D |
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