My Mini Aleph progress

fredv

Don't want to side track the other thread.
So, here is how my Mini-Aleph looks like currently.

As the other Fred, I also have doubt 10W is going to meet my needs, but the experience to try something new is always fun which is what this hobby brings I have a couple Fostex 207E which may help a little.

I wish I had better tools, but a hack saw and electric hand drill are all I have for now. The cabinets for the Fostex are still nowhere insight, sigh. Does anyone want to give me some advise what are the basic tools that I will need to build speaker cabinets. Yeah, table saw, I know, but my significant half shut me down twice already. I am working on a coup to smuggle whatever needed into the house first and then .......... I worry about that later :-)

Systems

Lookin good,I bet it will sound good with the Fostex.



As for tools table saw and router are indespensible.If you can't swing for the table saw, HD or Lowes will usually cut big panels to size.A skill saw or even a jig saw with a cutting guide would also work.

Face

For a router, pick up at least a Craftsman plunge router and one of these: http://www.amazon.com/Jasper-200J-Circle-Cutting-Plunge/dp/B00009K77A/ref=pd_bbs_sr_1?ie=UTF8&s=hi&qid=1240011988&sr=8-1

ShinAce

Was just about to say the same thing GV said, then he said it.

Table saw and router are the way to go. The quick thing to do is 45 degree mitre joints for easy sanding. Otherwise, there are many better but more complicated ways of doing it.

The scenic route is with a circular saw and guide(clamped scraps), and jigsaw(reciprocating saw) for the holes.

10 watts? Those are some huge motherf$%^ing heatsinks. Well done! I don't remember the mini-aleph but I'm guessing a single ended class A MOSFET or BJT. Looks good too. Did you solder it all?

Let us know how it sounds.

p.s. Did you know you can make cabinets with a tablesaw? hint....

Face

With the amount of heat my Aleph 5 clone gives off, I would not feel safe using a piece of wood as part of the enclosure.

fredv

The router is for cutting the circular opening, right? Sounds like I shall get one of these first as I probably can pay a little to the lumbar shop to cut the big panels for me. You guys are talking too much about building speakers and are making me itching !!!

Face

If your wife is that against using power tools in the house, you should probably consider using the router outside, especially using MDF. I should post a picture of the shop in my basement.

Systems

Whats the total capacitance?I see you have the big cans plus 6 smaller ones that appear like they might be 10,000uf ish ea?

fredv

ShinAce,

Yes, it is a class A MOSFET SE amp. The heat sink are not small in terms of length and width, but the fins are too short. I did test the soldered board for proper electrical measurements before I set up the chassis. Without the enclosure, the sinks were only warm, maybe at high 30's and low 40's. So, I know I can up the bias, just not sure by how much yet.

Face,

She is against my tools in general because I never build anything that she wants :-) The wood deck in my backyard is my work shop. When I am done, I just sweep all the dirt the underneath :-)

GV,

The PS board has 6 x 12,000uF caps in CRC set up. The big caps were given to me my my friend who used them on a 2A3 filament supply. These are 35,000uF Sprague's. I reformed them over a 2 days period and tested good. So, I just put them in use and going to hook them up // the last C's. The total will be 71,000uF per rail. I am waiting for my CL-60's to come so that the fuse won't be blown upon power up by the inrush.

The front panel is going to be a 3/4 red oak board, only a few buck at HD and looks quite good. The back panel is perforated aluminum. So, I can hang a low speed fan there if heat becomes an issue. The top is an Lexan type panel that I bought for a few bucks - again, convenient and low cost. Later on, I probably will replace it with another perforated aluminum plate.

Systems

fredv wrote: »

The total will be 71,000uF per rail. I am waiting for my CL-60's to come so that the fuse won't be blown upon power up by the inrush.

Woooh 71k per rail for a 10w amp.:eek:Awesome. Yeah without a softstart it would be like a dead short at turn on,better have a high current bridge rectifier.

strider

Try building something she wants, something that looks complicated but isn't. That's how I got my table saw and circular saw. While you're building her piece, it's a lot easier to slip in some speaker cabinet panels.

I was able to make all the cuts on my Fonkens with a circular saw and cutting guide, with the exception of the final 45 degree chamfers down the front of the cabinet. If you're ever in need and don't mind dealing with shipping, I'd be happy to cut driver holes and recesses for a baffle for you.

I've got PSU and rectifier boards en route for an F5 clone. The heatsinks should he here soon as well; Conrad MF35-151's. They may be a bit overkill, but they look dead sexy. I'll look forward to your updates.

fredv

I think the "give some and get some" strategy will work especially the part to use the tool for something she wants first. That actually worked in the past!!

Which F5 did you end up buying, Peter's? or Christian's? The Conrad's are really nice. I do have extra desire Fairchild MOSFET's for the F5. Let me know if you need for the F5 project. I can send you 2 pairs for a stereo.

strider

fredv wrote: »

Which F5 did you end up buying, Peter's? or Christian's? The Conrad's are really nice. I do have extra desire Fairchild MOSFET's for the F5. Let me know if you need for the F5 project. I can send you 2 pairs for a stereo.

Both, actually. I'd bought the F5 boards from Peter but he didn't have any PSU boards left. Noticed that Christian had both the PSU and rectifier boards available so I bought them from him. His group buy thread has some really good info on building the F5 as well.

Thanks for the offer on the Fairchilds, but I think I'm going to try Vishays. I've heard they may sound a bit warmer. From what I've read, the F5 can exacerbate peaks in the frequency response of the speakers they're paired with; my Fonkens have a decent bump at about 6k. Hopefully with the Vishay's it might not be quite so bad.

heiney9

Fredv, awesome :cool::cool:.

Three cheers to all you DIY guys. Great choices and enjoy, I'm very envious as I don't have the skills to pull something like this off w/o a step by step how to.

I enjoy reading and seeing the pics in all your posts keep it up!!!

danz1906

Good-job!

fredv

heiney9 wrote: »

Fredv, awesome :cool::cool:.

Three cheers to all you DIY guys. Great choices and enjoy, I'm very envious as I don't have the skills to pull something like this off w/o a step by step how to.

I enjoy reading and seeing the pics in all your posts keep it up!!!

H9,

You can do it. It is pretty much follow the BOM and schematic and stuff the board. I think the hardest part is trouble shooting when it doesn't work as expected. I actually had a fair share of that. The board actually didn't measure up, and it took me a few days to find out the board's layout of the power fets was not in the "exact" ordering. When my first board was assembled, I got no CCS current at the output stage. It turned out Peter's board didn't have the first pair of FET's in the same mirror position. I found it was very educational while doing the trouble shooting. I really learned a lot in that process.

My inrush limiter came today. I tried to put the amp together before dinner. One channel is perfect, 28ms offset at output, but the other has 5V :eek: I think I managed to kill a transistor when I was assembling everything in to the chassis (I dropped the one channel to the carpet ....). If I can bring the second channel back before I go to bed, I will be happy like a clam.

fredv

Mini-Aleph is singing, and I am not dreaming

At the moment, the big caps are not in as I need the space to hook up my DMM. The amp is really dead silent, the only slight hum is from my tube rectified Grounded Grid Pre-tube, but I have put my ear within 6 inches of the Monitor 5 to detect this hum. My only complaint is the turn on thump, quite loud. Otherwise, it is perfect. Both channels have 28ma output offset.

The hot spot of heat sink is at 45C after an hour which happens to be the magic warm up time for the amp and pre to start sounding fluid. Yes, no kidding, there is a very noticeable SQ improvement from 30 mins to 60 mins. Consider I have only 10C to rise, it can be a little to stretch to aim at 1.5A bias. Anyhow, I just found that I didn't have the right resistors for the change. So, I will let it burn in as it is for now, and an update picture will be posted later.

Time to have a sweet dream :cool:

nikolas812

Thats Awesome Fred! Nice Job!

Now get us some more pics!:)




Nick

heiney9

EXCELLENT Fred, It is true my Aleph 30 really starts to open up after about 45 minutes. The first 30 minutes or so the amp sounds dark and closed in until it reaches proper temp/bias. I think most single ended Class A amps have this characteristic. I always try to wait atleast 30 minutes before sitting down to listen.

H9

fredv

Hi there,

Today, I removed the variac and powered it up at 100% main voltage. No loud thump, no blown fuse, looks like the 0.68uF X2 cap and double inrush limiters really helped to solve last kink.

I have been playing it a few hours 2 evenings in row. The sound is really sweet, and the mid is very fluid. The best description is - very natural sounding. However, it isn't forgiving - bad recordings really sounded bad.

Casualties of this project were not too bad, 2 x ZTX450, 1 x IRF9610, 2 fuses, and a few blood drops :-) The cost was at around $200, and a good portion was S&H. All in all, this is definitely the best $200 I ever spent.

Any complaint? Not really, I do wish it had a few more watts, but then this gives me the incentive to speed up build the cabinet for the Fostex .... Maybe a 2-way active crossover? 2 of these - one for the tweeter and one for the bottom.

Anyhow, here are a few more pictures for your entertainment. It looks a little odd, but then the material had to be something I could handle

Ender

Wow, looks beautiful and tidy. Very nice build. How loud can it get on the Monitor 5?

fredv

I only use a human SPL meter to test the loudness. She yelled at me to lower the volume. So loud enough to get me in trouble even with the Monitor 5's. However, I am talking about listening in the bedroom.

The gain stage is not very high. An active preamp is needed especially for some recordings that are recorded at lower volume level.

ben62670

Very cool Fred. I am liking your venture into SS;)
Take care.
Ben

fredv

Hi Ben,

I just love to try different types of gears, SS or tube, but don't have the deep pocket to support. So, DIY is the only way to fulfill my desire .... Obviously, I am a little bias on the the tube side, and I am still using a tube pre with the Mini-A :-) I believe good design wins, regardless to SS or tube. At the end, it will be pretty much personal preferences.

I also have a SimpleSE (like Nick's) needs to finish up. This is going to be a very interesting comparison - shoot out of 2 (SS and tube!!) Class A SE 10 watters. My biggest trouble is the metal work - figure out the easiest way to make an IEC hole off a 3/16" aluminum plate, my Greenline puncher wouldn't work One thing for sure, the SimpleSE is going to cost much more than the Mini-A. Just the iron's already exceeded the total cost of the Mini-A :eek: