Mechanical resistance (Rms) measurement could possibly give some clue?...
POS,
Thanks for that. I can look at that when I assemble some new drivers. But I am still curious how the small surface area change with the surround on the front vs rear of the cone would change the micro dynamics of the sound if it was shown that the Rms actually stays the same. Perhaps the radiated sound off the edge of the cone has a rise in output, that is conceivable without damping that surface area and not just terminating the end of the cone which is one of the major functions of the surround besides the other physical reasons to have a surround.
Thanks for that. I can look at that when I assemble some new drivers. But I am still curious how the small surface area change with the surround on the front vs rear of the cone would change the micro dynamics of the sound if it was shown that the Rms actually stays the same. Perhaps the radiated sound off the edge of the cone has a rise in output, that is conceivable without damping that surface area and not just terminating the end of the cone which is one of the major functions of the surround besides the other physical reasons to have a surround.
Well, that explains a few things. There are small drivers I like, and large drivers, but not the in-between sizes. I was surprised that 12" and 15" drivers could sound so lively in the midrange; not what I expected at all. But some were very dull and undynamic, and obviously intended only for deep bass and subwoofer duties.
I agree completely the proof is in the listening; if sparkle, shimmer, and vivid tonality aren't there, no amount of crossover EQ or digital processing is going to bring it back. Some drivers have these qualities, and others don't.
One of the properties of the JMLC horn is the diaphragm sees resistive loading (horn action) right down to the 500 Hz horn cutoff; the horn is optimized for uniform loading, not directivity control. This has an effect on the sound; it sounds like a large-format horn, not a small waveguide on a 1" dome tweeter. The AH425 isn't the biggest JMLC around, but in terms of dynamics, it sounds more like a Altec 1005 multicell than a 511 or 811 sectoral horn (which have more uneven diaphragm loading as well as pattern flip).
This, in turn, asks more of the bass driver. If the bass unit sounds like a small-format direct-radiator, the difference in tone color and dynamics is very obvious. I'm pretty sure that no 10" direct-radiator would be a good match, and one or more 15" drivers, or a bass horn, are better choices.
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This is what makes DIY so much fun......and valuable for those looking to maximize performance based on their personal tastes and other factors. Most would agree in the end, the results are all purely subjective anyways. It's probobly the primary reason I've been visiting this thread for years now.
Sure the horn sytem isn't going to change it's character much between good amplifiers. A high priority with multi amp horns is how quiet they are and how much inner detail they have when the music gets soft. That is more important then power - any amp will get loud with a 110 db/w system but a good amp will allow the inner weaving of the music to be played back with beauty and life. I have some amplifiers with SE 45 outputs and although they have enough power to play "loud" they are too dirty to convey the low level inner detail and beauty of a good SS amp
You can make class A sound any way you like. I reckon no two JLH amps to same basic design would sound the same other than by chance. And certainly I agree with the 1 watt importance or impotence - ha! not laughing at you but just at my choice of word because a lifeless 1 watt is a quick indication of perhaps much work ahead.
Sunn Beta copies biased to 5-7 watts class A with lots of heatsink sounds perfect to me with my horns. 300B, 2A3, 6C33, 45 amps are collecting dust. If it's tubes with horns I like EL84 PP
Sunn Beta copies biased to 5-7 watts class A with lots of heatsink sounds perfect to me with my horns. 300B, 2A3, 6C33, 45 amps are collecting dust. If it's tubes with horns I like EL84 PP
What you say falls in line with what I have found. I make my own SS amps, and the 845 is gathering dust. I was going to build a Karna and I note Gary Dahl interest in SS. I was there about 1987 with a Krell type of construction, but I could not get the passive parts you can get today. I think there may be rennaisance in discrete solid state amps.
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I'd love to hear a good EL84 PP amp on my horns. Currently I am using PP 300B's. They sound great, but I would be happier if they were quieter.
This summer I will build Gary Pimm's 20-watt class A solid-state amp design. I liked the way his own unit sounded with my speakers. It will be interesting to find how it compares with my tube amps, which were out of service at the time.
Gary Dahl
This summer I will build Gary Pimm's 20-watt class A solid-state amp design. I liked the way his own unit sounded with my speakers. It will be interesting to find how it compares with my tube amps, which were out of service at the time.
Gary Dahl
Yes Pooh, I concur with this. That may be why we have systems that deliver. I really cannotdo morethan go louder with horns but when will I repro at 110dB except on peak transients. I can never use my watts fully.
I've heard 300b amps on full horn systems with no noise that I could hear.
Do you have thoughts on where the noise comes from?
I'm by no means an amp guru. My late uncle was and he used to come over and LOL when he saw me building the little SET amps. His system used to be all Altec all the time but as he got older and moved into smaller places he switched over to magnepans with subs. He was "the man" when it came to boutique guitar amps and servicing big name guitarists (Walsh , Clapton, Seals
amps ect.. Well he decided when he went to Magnepans he wanted more power so he took what he felt to be the absolute best sounding solid state guitar amp, the SUNN, and used the basic circuit to design some high fi amps - that evolved into the amps he built for me and my horns. The amps are dead quiet and have really transparent sound. He built quite a few of them after he had some boards made. Mine are 60 watt, 35 and 12 watts. I also have his original personal 100 watt mono amps he built for his Magnepans. One of them developed some noise - I need to see if i can get it working properly. When he passed I got all of his music collection - mostly classical albums from 50's on , hifi, test gear, parts, tubes, schematics, guitar ect.. still haven't been able to go through it all - lots of stuff - many parts from the 60's ect
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The topology has been posted in this thread, but I'm not yet sure when (if ever) I will post a crossover schematic with part values. Mine won't really even be finalized until late summer when I get a chance to move my speakers to a place where I can set up an appropriate environment for getting cleaner measurements. Also, my part values wouldn't provide the same results in someone else's system anyway (different cabinets, room, etc.), so they would be of limited use.
You can find a schematics of the prototype of Gary Pimm's amp near the middle of this page. He hasn't published a schematic for the current 25W version on his site, but you could ask him.
Gary uses transformers in order to be able to run the transistors at high idling current levels where their linearity is greater and their input capacitance is greatly reduced. It is a very unusual design and a superb performer.
Gary Dahl
Some of it is mechanical noise from the power supply iron, which was scavenged from Lynn's discards. At the time, I was trying to build his design "on the cheap" making use of every recycled part I could come up with. I have another set of power iron waiting in the wings and will install it when I get a chance.
The rest of the noise is there because of imbalance between the output tubes. The circuit doesn't have a hum balance pot, making its noise level dependent upon the matching of output tubes. My current set of output tubes don't match as well as the ones I have had in the past, unfortunately. The "matched quad" has two tubes that match, and two that are off in opposite directions. If I use the matched pair in one channel, it runs silently (except for the power iron, of course), but the other channel is too noisy. Best results are obtained by splitting up the pairs. Or I could order more tubes, of course.
Lynn doesn't have the matching problem in his own amp because he has a special circuit for canceling the hum...another good project for me in the future.
Gary Dahl
Wait , what , rennaisance in discrete SS amplifiers .....
Probably not in Lynn's thread.