Nigel,
The BF862's are probably my next obsession. They are so cheap and reportedly so good.
I had read this entire thread. Its not to long. I have had amps change, or my attitude toward them change, over time so I wanted to know if it had changed in the few months you have been listening. I love the F5 but I do think that something softer would be nice. If I decide to build one I will definitely let you know and contribute to this thread if thats okay.
Thanks for your response. Your approach to DIY is admirable. You learn so much and are so stubborn in a good way to learn about the circuit as well as being open to a better option. I like reading your posts.
Uriah
The BF862's are probably my next obsession. They are so cheap and reportedly so good.
I had read this entire thread. Its not to long. I have had amps change, or my attitude toward them change, over time so I wanted to know if it had changed in the few months you have been listening. I love the F5 but I do think that something softer would be nice. If I decide to build one I will definitely let you know and contribute to this thread if thats okay.
Thanks for your response. Your approach to DIY is admirable. You learn so much and are so stubborn in a good way to learn about the circuit as well as being open to a better option. I like reading your posts.
Uriah
At this point I am definitely obsessed with them. (I found myself wondering last night if the 2SK170s in Salas' regulator circuit could be replaced by them...) Apart from being cheap and good, it is easy to include a whole bunch of them in an order from Mouser, say, to make the minimum postage to Brazil worthwhile, whereas the 2SK170s are not available from the big companies...
You're right about attitudes towards amps changing. If time and kids permit, later on I will try to repeat a direct comparison with the F5, and will report here.
That's nice to hear, thank you. I worry sometimes that I ramble on too much...
Best of luck with the build.
Cheers
Nigel
Absolutely. The only limiting difference is the Vds max (20V BF862 - 40V 2sk170) but with a little help of cascoding it's not really a problem.
I'm soldering up a regulator this evening, using the Salas' schematic from the symmetric B1 thread, using some 2SK170 I had left over from an old project.
If I use this circuit (or some variant) on the big project then I may try what you're suggesting. By cascoding here you mean using a bjt (BC550 or something) above the drain, like some people were doing on the F5 thread?
Cheers
Nigel
cascoding device usually means that another active part is stacked on shoulders of main part , so active part is working in constant voltage conditions ;
there are many variables involved for proper implementation , but they're pretty much explained in some articles of Borbely and Papa ;
look for Cascode pdf,Sweet spot pdf at Papa's , usual Borbely articles etc
example certainly is F5 cascoded ( somewhere in thread ) , also Pumpkin and Shunty ..... and numerous ones
there are many variables involved for proper implementation , but they're pretty much explained in some articles of Borbely and Papa ;
look for Cascode pdf,Sweet spot pdf at Papa's , usual Borbely articles etc
example certainly is F5 cascoded ( somewhere in thread ) , also Pumpkin and Shunty ..... and numerous ones
Hi Guys,
I promised I'd report back on a repeat of the comparison with the F5. Today was my first chance to get the living room free of the kids, so here's my report.
I tried both the F5 and the mini-Aleph-J-BF862 with the BF862 preamp from juma's thread and the passive symmetric BF862 buffer which I've mentioned elsewhere I'm using for testing some stuff. I listened to solo piano (Artur Pizarro playing Beethoven sonatas from Linn records - highly recommended!), voice (Elisabeth Schwarzkopf singing Strauss' Four Last Songs - even more highly recommended, but you probably all know this one already, right?
), and part of the first movement from Mahler 2 (Solti and the CSO; needs no recommendation from me )
My impressions remain overall as they were last October, as described above. The amp has a slightly warmer sound than the F5 (I dislike using such subjective terms without any measurements to go with them, but I have no oscope...). This was clearest with piano and voice, much less so in the Mahler. Even so, we're talking about slight differences here. I wonder if this is the "single-ended sound" people talk about, with a little second harmonic?? I still prefer the F5 in the living room, for the extra "oomph", but I would choose either of them in preference to anything else I have in the house.
It's moments like this I really wish I had an oscilloscope and could measure things...
Cheers
Nigel
I promised I'd report back on a repeat of the comparison with the F5. Today was my first chance to get the living room free of the kids, so here's my report.
I tried both the F5 and the mini-Aleph-J-BF862 with the BF862 preamp from juma's thread and the passive symmetric BF862 buffer which I've mentioned elsewhere I'm using for testing some stuff. I listened to solo piano (Artur Pizarro playing Beethoven sonatas from Linn records - highly recommended!), voice (Elisabeth Schwarzkopf singing Strauss' Four Last Songs - even more highly recommended, but you probably all know this one already, right?
), and part of the first movement from Mahler 2 (Solti and the CSO; needs no recommendation from me ) My impressions remain overall as they were last October, as described above. The amp has a slightly warmer sound than the F5 (I dislike using such subjective terms without any measurements to go with them, but I have no oscope...). This was clearest with piano and voice, much less so in the Mahler. Even so, we're talking about slight differences here. I wonder if this is the "single-ended sound" people talk about, with a little second harmonic?? I still prefer the F5 in the living room, for the extra "oomph", but I would choose either of them in preference to anything else I have in the house.
It's moments like this I really wish I had an oscilloscope and could measure things...
Cheers
Nigel
Thanks a lot Nigel. I read the Aleph SHOULD sound a little warmer.
I should be building one soon. After I mail out all my LDRs and boards I will get down to business. My Chip Amp is giving up the ghost. Something starting to sound tizzy when the speakers hit harder in midrange. Maybe a cap is dying or a joint has shown my poor soldering skills. I dont really feel like fixing it. Will salvage some parts for this.
Thanks so much.
Uriah
I should be building one soon. After I mail out all my LDRs and boards I will get down to business. My Chip Amp is giving up the ghost. Something starting to sound tizzy when the speakers hit harder in midrange. Maybe a cap is dying or a joint has shown my poor soldering skills. I dont really feel like fixing it. Will salvage some parts for this.
Thanks so much.
Uriah
Hi Uriah,
Since my last post I have been wondering idly about how you would scale this amp up, to full Aleph-J size. I'm sure juma could spot any inherent problems straightaway, but if your speakers aren't very high-efficiency, or if you aren't planning to use it in a very small space, like I do, then it might be
an idea to consider a larger version. (Might be fun, even if you don't need it... ) Would it be as simple as just doubling up the output stage, so that you'd have a total of 4 IRFP9240's per channel... ? Perhaps you'd have to adjust the longtailed pair also - I'm not sure how.
I never gave this any thought; as the original post says, I was looking for something about this size, and it has turned out more than sufficient for its intended purpose. Nonetheless it would be interesting to think about how it could be done, and it may suit your needs better.
Cheers
Nigel
Since my last post I have been wondering idly about how you would scale this amp up, to full Aleph-J size. I'm sure juma could spot any inherent problems straightaway, but if your speakers aren't very high-efficiency, or if you aren't planning to use it in a very small space, like I do, then it might be
an idea to consider a larger version. (Might be fun, even if you don't need it...
) Would it be as simple as just doubling up the output stage, so that you'd have a total of 4 IRFP9240's per channel... ? Perhaps you'd have to adjust the longtailed pair also - I'm not sure how. I never gave this any thought; as the original post says, I was looking for something about this size, and it has turned out more than sufficient for its intended purpose. Nonetheless it would be interesting to think about how it could be done, and it may suit your needs better.
Cheers
Nigel
Well, the size was actually something that drew me to the thread. I was looking for BF862 applications and ideas and then saw you looking for low wattage. I would like to use some small sinks I have but it looks like I still need decent sinks. Anyway, speakers are 99-100db in their cabs. 96db out. Less than a watt suits me most of the time.
Uriah
Uriah
With speakers as efficient as that I'm sure you don't need to upscale. (Unless you want to use them in the Astrodome or something...) Out of interest, what speakers are you using?
Heatsinks are a different story. I can't remember if I posted the dimensions of mine above or not, but each channel has a black-anodized heatsink approximately 8" high and 6" wide, with a base more than 1/4" thick, and 15 vertical fins 1 and 1/4 " deep. They get hot, as discussed above, and anything significantly smaller would be insufficient, but anything larger would be unnecessary, also.
Cheers
Nigel
Same size as F5.
The speakers are Audio Nirvana Super 12" in a bass reflex cab. I find them incredible. Its up in the air about getting some Magnepans. Wish I could hear them both in the same room. The bass is lacking a bit but that is par for the course with full range and a passive pot.
Uriah
The speakers are Audio Nirvana Super 12" in a bass reflex cab. I find them incredible. Its up in the air about getting some Magnepans. Wish I could hear them both in the same room. The bass is lacking a bit but that is par for the course with full range and a passive pot.
Uriah
Hi Uriah,
Are your boxes the ones here Audio Nirvana Super 12 Bass Reflex Speakers • DIY Audio Projects Forum ? (Google just produced this, and I noticed home city os the same as yours... )
Here's a couple of random observations:
1. I'm sure you won't need any more power than this amp provides. My speakers in the living room, which is large, are B&W monitors, and only 87db/W, so the extra power from the F5 makes a difference. I'm sure you won't "need" any extra power. (Whether you "want" it or not is a totally different question, of course...
)2. You mention a passive preamp. Is this a lightspeed? If you're going to be buying BF862 anyway, why not consider juma's BF862 preamp with a gain of 2? This would be a nice match if you ask me. (It sounds great on my system, anyway). People who know more than I do might be able to answer if the match is good in a technical sense, as it (apparently) is for the F5.
(juma: any chance you could shed some light on this?)
I've looked at the circuit for the BA-2 several times and thought "ooohhhh..." and then "hhmmmm...", but I have to rule it out for the time being since it is too hard/expensive down here to get heatsinks and trafos for it. Now, I grant you it will bring more "balls", but why would it bring more "warmness" than the smaller amp here?
Cheers
Nigel
Dont know if BA-2 will bring more warmth than tweaked Mini-A, probably not.
I think it may offer more control than Mini-A, and on par with F5 on the bottom end.
I've heard Udailey's speaks, they need a bull to drive them IMO. I think they are more neutral in tone compared to a fostex for instance.
I think one could build a BA-2 with less output Fet's and bias down a little and get most of the performance. Don't get me wrong. I am also very pleased with the F5. I am running Toshiba FET's in right now, and the tone is more smooth compared to Fairchilds.
Sorry to float offtopic.
I think it may offer more control than Mini-A, and on par with F5 on the bottom end.
I've heard Udailey's speaks, they need a bull to drive them IMO. I think they are more neutral in tone compared to a fostex for instance.
I think one could build a BA-2 with less output Fet's and bias down a little and get most of the performance. Don't get me wrong. I am also very pleased with the F5. I am running Toshiba FET's in right now, and the tone is more smooth compared to Fairchilds.
Sorry to float offtopic.
G'Morning Guys,
They do need something Class A to bring out the best. OMG Tea-Bag you should have heard them in this Audio Get Together we had in Austin. Blew my mind. We used Bruce Heran's Oddwatt Class A tube amps with KT77's and KT88's in it. The KT77's blew the KT88's away. The sound was the best I have heard the AN's. I really think that tubes are the way to go with these speakers but the cost and voltage are both out of my range right now.
The F5 was a great amp for them. It forced them to produce tight controlled bass and I was really happy listening to it that way. There was something amiss though and I think thats why I havent had a need for the F5. Dont get me wrong, having an F5 on them would probably stop me from trying to build another amp for a long time, but I knew what I was missing when I heard the tubes which brings us back to the Aleph's because I have heard that they are a bit tubey and softer/smoother/silkier whatever, than a lot of other SS amps.
Nigel, Yes those are my speakers and Yes I was referring to the Lightspeed. The Lightspeed is freakin fantastic and I frankly cant live without one in my system. To me its the real Audio Nirvana. There are some things to improve in it but the one thing that you cant improve is the fact that in the signal is just a resistor and then one more resistor to ground. 2 resistors. No contacts. Better sounding resistors than any other. In some systems a buffer is an advantage, in others there is no buffer necessary. Being able to mess with the impedance of the Lightspeed is a great advantage over the original circuit because even more systems now dont need a buffer but this is one of the reasons I was looking into BF862. The buffer with them is so simple and I have been thinking I could even incorporate LDRs as resistors in the buffer circuit to see what the difference is. I have been wondering about using them as resistors in circuits as often as possible and this would be a good place to test that out. However lower than 40 Ohms is not very possible unless I parallel and then thats only a good idea to do about once or twice. Meaning using two or three in parallel before it starts to get ridiculous. LDRs are a lot of fun and for me have become some sort of an obsession.
Uriah
They do need something Class A to bring out the best. OMG Tea-Bag you should have heard them in this Audio Get Together we had in Austin. Blew my mind. We used Bruce Heran's Oddwatt Class A tube amps with KT77's and KT88's in it. The KT77's blew the KT88's away. The sound was the best I have heard the AN's. I really think that tubes are the way to go with these speakers but the cost and voltage are both out of my range right now.
The F5 was a great amp for them. It forced them to produce tight controlled bass and I was really happy listening to it that way. There was something amiss though and I think thats why I havent had a need for the F5. Dont get me wrong, having an F5 on them would probably stop me from trying to build another amp for a long time, but I knew what I was missing when I heard the tubes which brings us back to the Aleph's because I have heard that they are a bit tubey and softer/smoother/silkier whatever, than a lot of other SS amps.
Nigel, Yes those are my speakers and Yes I was referring to the Lightspeed. The Lightspeed is freakin fantastic and I frankly cant live without one in my system. To me its the real Audio Nirvana. There are some things to improve in it but the one thing that you cant improve is the fact that in the signal is just a resistor and then one more resistor to ground. 2 resistors. No contacts. Better sounding resistors than any other. In some systems a buffer is an advantage, in others there is no buffer necessary. Being able to mess with the impedance of the Lightspeed is a great advantage over the original circuit because even more systems now dont need a buffer but this is one of the reasons I was looking into BF862. The buffer with them is so simple and I have been thinking I could even incorporate LDRs as resistors in the buffer circuit to see what the difference is. I have been wondering about using them as resistors in circuits as often as possible and this would be a good place to test that out. However lower than 40 Ohms is not very possible unless I parallel and then thats only a good idea to do about once or twice. Meaning using two or three in parallel before it starts to get ridiculous. LDRs are a lot of fun and for me have become some sort of an obsession.
Uriah
I had F5 in mind when I made that preamp, but it will sound great with almost any amp and source. Simply, it's a good preamp. I'm not willing to elaborate further because futile debates with nitpicking "gurus" really make me tired...
Hi juma,
That's understandable. And the preamp does sound great with this amp, as well as with the F5, so whether it's a good technical match in terms of gain and power is a side-issue really.
Cheers
Nigel
Yes, that's the easy part: preamp has 6dB gain, max output is 6-7Vpeak, Zout is about 25-30 ohms. The rest is easy to calculate...
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