hey, i finally got all my boards and am ordering supplies and have a couple questions regarding the MPSA18 transistor...
i was told that the BC546B is a bit better than the MPSA18. so, the questions, which is better, where is the best place to get them, and do i need to do matching?
pretty straight forward, thanks.
i was told that the BC546B is a bit better than the MPSA18. so, the questions, which is better, where is the best place to get them, and do i need to do matching?
pretty straight forward, thanks.
At one point in time I asked Nelson, "I note you change from the MPSA18s to ZTX450s between the A5 and A4. The later are much easier for me to locate and I wondered if they were exchangeable"
To which he replied, "The bipolars in this circuit are completely generic, and the ZTX450's were chosen for price and availability. np"
That is, any equivalent will do.
cheers, mark
To which he replied, "The bipolars in this circuit are completely generic, and the ZTX450's were chosen for price and availability. np"
That is, any equivalent will do.
cheers, mark
I am silly. My friends call me so.
Whatever I make, I use only the matched components.
Matched transistors...
Matched JFETs...
Matched MOSFETs...
Matched caps...
Matched coils...
Matched resistors...
Matched cable length...
Matched chassis...
Matched transformers...
Matched knobs...
Matched bridge diodes...
Sound silly, but this is the right solution.
Please believe in me. Just go ahead.
Whatever I make, I use only the matched components.
Matched transistors...
Matched JFETs...
Matched MOSFETs...
Matched caps...
Matched coils...
Matched resistors...
Matched cable length...
Matched chassis...
Matched transformers...
Matched knobs...
Matched bridge diodes...
Sound silly, but this is the right solution.
Please believe in me. Just go ahead.
yeah, actually, i over-ordered everything...
im gettting like 3600+ resistors alone just so it is all matched.
the black gates (220uf) will be the only non-matched component. even the small caps on the board will be matched. eh, since the transistors are so darn cheap, ill just match them as well i guess.
im gettting like 3600+ resistors alone just so it is all matched.
the black gates (220uf) will be the only non-matched component. even the small caps on the board will be matched. eh, since the transistors are so darn cheap, ill just match them as well i guess.
I use MPSA42.
I use ZTX450 too.
I use 2N6517 too.
All matched.
I have only one power amp. So, I use the above three
simply to replace in turn, whenever I get to feel boring.
It¡¯s fun of soldering and re-soldering. Yeah...it is indeed.
If it is NPN transistor,
if it has big enough CE, CB and EB breakdown voltage rating,
if it works hard-saturated, and
if it has a base-emitter potential of about 0.66V,
which one?, does not matter. This is my lesson from a book and
the articles of Nelson Pass.
Cowanrg...
I was teaching a shark how to swim...
I use ZTX450 too.
I use 2N6517 too.
All matched.
I have only one power amp. So, I use the above three
simply to replace in turn, whenever I get to feel boring.
It¡¯s fun of soldering and re-soldering. Yeah...it is indeed.
If it is NPN transistor,
if it has big enough CE, CB and EB breakdown voltage rating,
if it works hard-saturated, and
if it has a base-emitter potential of about 0.66V,
which one?, does not matter. This is my lesson from a book and
the articles of Nelson Pass.
Cowanrg...
I was teaching a shark how to swim...
jh6you,
It seems like any respectable BJT will do in this situation. I have even built a test circuit using the venerable 2N2222 in place of the ZTX450/MPSA18 for the Aleph current source. Worked pretty good with a hfe of ~125.
I wonder what the minimum hfe would be in this situation. I might tinker with this tomorrow if I get some time.
cowanrg,
8-100W Class A Amplifiers?! I hope that your climate control system is up to the task. Don't each of these amplifiers idle near 400W?
Later,
It seems like any respectable BJT will do in this situation. I have even built a test circuit using the venerable 2N2222 in place of the ZTX450/MPSA18 for the Aleph current source. Worked pretty good with a hfe of ~125.
I wonder what the minimum hfe would be in this situation. I might tinker with this tomorrow if I get some time.
cowanrg,
8-100W Class A Amplifiers?! I hope that your climate control system is up to the task. Don't each of these amplifiers idle near 400W?
Later,
I just hope you have a dedicated line rated at 120 VAC @ 30 amps or a 220 VAC dedicated line rated @ 15 amps just for the power amplifiers. You will need at least 10 awg wiring to the outlets @ 115 VAC. Six channels of Aleph 2 is about 1800 watts constant draw which is a tad too close for a 120 VAC, 20 amp circuit. A 120 VAC 20 amp circuit may not be safe if the run is long. A long run could be a fire hazard due to heat dissipation in the wiring. It looks as if your best bet is either a 120 VAC 30 amp circuit or wire the Alephs for 220 VAC and run a 220 volt line (if your trannies have dual primaries). I also hope you have at least 150 amp service or better in your home especially if you electric appliances. All in all though, having 8 Aleph 2's is not a bad problem to have.
wow, brought back from the dead huh!
i have since scaled back my designs for my main system and will probably only include 2 aleph2's, in addition to my 2 aleph3's i currently use. i dont have the time, money, or energy to finish off all my cases that i have right now. i will be just finishing two of them, and leaving the others for another project.
i have since scaled back my designs for my main system and will probably only include 2 aleph2's, in addition to my 2 aleph3's i currently use. i dont have the time, money, or energy to finish off all my cases that i have right now. i will be just finishing two of them, and leaving the others for another project.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.