I cant take credit for the extension job, I was planning to bolt everything (front and back right to the heatsink, and Westend showed me his case, so I had him make mine the same. A surprise benefit is that you can hog out the through holes in the angle pieces a little larger than necessary, and it gives quite a bit of Play in fitting the panels if one of you holes is slightly out of place, or a panel needs truing.
Russellc
One of the best I've heard period. Cant believe it came from my solder gun!
Face plate isnt attached yet and the power cords are temporarily installed. Note that the grounds arent yet attached, and while not safe to leave, I must say this amp is quiet. In the left speaker with your ear right up against a JBL 2235H, a very slight hum is just perceptible. I am over stating to speak of this as a "hum"......you couldnt hear it at all in anything but a dead quiet room, and only with your ear right up next to the driver.
Wow! 2 x 400VA toroids?? Those contribute a lot to the stability of DC offset. It is better to use large trannies than large filter capacitors. Nice job !!
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The input wires are shielded Cardas interconnect cable. The shield is not grounded nor is much else with this temp connection. It is so quiet you cant tell if its on or not, even on power up and power down. Absolutely silent.
The left channel, in a dead quiet room with your ear right up against the 15 inch JBL 2235H, a very, very slight m-m-mm-m- can be heard, JUST BARELY!
I'll have to look, but I think I used 300 VA transformers. Once warm this morning, it measured exactly as it did last night, spot on.
russellc
The heat sinks came from M&M Metals, I'll have to check for the weight. Order 4. Its only 20 bucks more than 2. If I remember correctly, it was 90 someodd a piece for 2, or 200 for 4. the delivery was quick, came in 2 boxes with 2 sinks in each. I believe these are just a touch over 12 inches wide, and about 8 inches high.
Russellc
Russellc,
you don't need your wires to have those 90 degrees angles - that makes them unnecessary long. You want your wires to be like mediterranean women - thick and short
You mean I should re-wire or get a new wife?
russellc
The M&M Metal site says 10.3 lbs per foot as their estimated weight. Mine were only 8 inches long, and at 12 inches wide it keep the amp at a very reasonable temp. I didnt think they weighed that much but I suppose they would know.
russellc
I guess so.It is approximetly 3 kilograms then.I used 45cm long 10cm high (about 1.5 kilograms) in the past and it make amp very hot.It was inadequate to cool well.I could not touch the cooler for 5 seconds
(Nelson's method)This size with F-5 gets fairly warm, but not hot. You can touch it, lay your arm on it whatever, not to hot, even under fairly heavy use. I think the aluminum case helps as well, the whole amp acts like a heat sink.
Russellc
You mean I should re-wire or get a new wife?
russellc
Start rewiring and see where will it take you...
Start rewiring and see where will it take you...
Right now its dead quiet and I dont see the need. Lord, some guys had leads from the boards to the outputs longer than this. It could be neatened a little but it works well, and is quiet as a mouse even on Altec A-7s with 100 db plus sensitivity. I think I'll get the power inlet cords properly wired along with the grounds and thermistors and call it a day. I'd rather have just a little extra length than anymore messed up board traces!
Russellc
Oh, that makes things a little more clear. I suppose it wouldnt be too much of a sin to cut it shorter and splice it? I hate to unsolder that larger gauge white teflon wire. It was a close fit to the hole, and its easy to pull the pad and maybe trace too. Splicing wouldnt add more resistance as well I suppose? One of the leads goes to the star ground on the power supply, and are soldered to a bare wire loop which attaches the two power supply sides of each power supply card together. It would be easy to shorten and rehook it to the loop with out risking any pads or traces. What say on the splicing question? I really hadnt considered the power supplies impedance.
Russellc
Can anybody recommend a good, fast diode that is relatively cheap for using with an F5? I have some MUR3060s in my Digikey shopping trolley right now, but at $40 for eight, I'd prefer to find something a bit cheaper if possible. I am using 8 because I'd rather it was 2x mono from the secondaries onwards.
Also, what does Nelson use in his commercial model?
Thanks
Also, what does Nelson use in his commercial model?
Thanks