They probably think we're nuts...
10" x 10"? That's a big chunk of hardware, flg!
Phone wire isn't so bad... at any rate, my horn doesn't hum or hiss with the JBL amp.
Just for kicks, I reconnected my ZV7-T to the center channel (yes, I run it balanced) and listened carefully to the center channel only. I think the amp is very revealing, so much so that it picks up any hash in the recording. Most of what I listen to are iTunes downloads. When I switch to a standard CD the hash (what little there is) disappears. At idle, I can stick my ear in the horn and can't pick up any hum, hiss, or distortion. My sweety must be part bat.
(but only the good parts -- try to figure that one out, ha).
This amp is very strong with a JBL 2446 driver/horn combination. My ears are smarting from the spanking the JBL just gave them -- albeit a spanking with a silk hanky.
Even up loud, the warmth and sparkle hangs in there. Silky, warm, smooth, class A.
Later, my friend,
John
10" x 10"? That's a big chunk of hardware, flg!
Phone wire isn't so bad... at any rate, my horn doesn't hum or hiss with the JBL amp.
Just for kicks, I reconnected my ZV7-T to the center channel (yes, I run it balanced) and listened carefully to the center channel only. I think the amp is very revealing, so much so that it picks up any hash in the recording. Most of what I listen to are iTunes downloads. When I switch to a standard CD the hash (what little there is) disappears. At idle, I can stick my ear in the horn and can't pick up any hum, hiss, or distortion. My sweety must be part bat.
(but only the good parts -- try to figure that one out, ha).This amp is very strong with a JBL 2446 driver/horn combination. My ears are smarting from the spanking the JBL just gave them -- albeit a spanking with a silk hanky.
Even up loud, the warmth and sparkle hangs in there. Silky, warm, smooth, class A. Later, my friend,
John
The daughter's golden ears...
I asked Ellen's daughter to listen to my arrangement -- her ears are so good she can hear the phone ringing downstairs and recognise who's leaving a message; I can't even hear the phone ringing. Anyway, she says she doesn't hear anything out of the ordinary, distortion wise, when she listens to one of her CDs on my system. Maybe I'm right, the noise Ellen heard was inherently embedded in my iTunes CD.
John
I asked Ellen's daughter to listen to my arrangement -- her ears are so good she can hear the phone ringing downstairs and recognise who's leaving a message; I can't even hear the phone ringing. Anyway, she says she doesn't hear anything out of the ordinary, distortion wise, when she listens to one of her CDs on my system. Maybe I'm right, the noise Ellen heard was inherently embedded in my iTunes CD.
John
Re: The daughter's golden ears...
umm . . . there is nothing . . . there is no noise . . .
but . . . you have something . . . there is nothing else . . .
how much she likes that something . . . ?
carpenter said:I asked Ellen's daughter to listen to my arrangement -- her ears are so good she can hear the phone ringing downstairs and recognise who's leaving a message; I can't even hear the phone ringing. Anyway, she says she doesn't hear anything out of the ordinary, distortion wise, when she listens to one of her CDs on my system. Maybe I'm right, the noise Ellen heard was inherently embedded in my iTunes CD.
John
umm . . . there is nothing . . . there is no noise . . .
but . . . you have something . . . there is nothing else . . .
how much she likes that something . . . ?
Babowana -- I think you are smarter than your nickname gives credit --
The girls are so use to hearing my pro-audio/class A audio gear that they aren't surprised by my acomplishments anymore. Besides, doesn't a parent think that their child is the cutest, smartest of the bunch? It's only natural that I think more of my gear than they do...
John
The girls are so use to hearing my pro-audio/class A audio gear that they aren't surprised by my acomplishments anymore. Besides, doesn't a parent think that their child is the cutest, smartest of the bunch? It's only natural that I think more of my gear than they do...
John
It's been awhile...
I'm studying Nelson's earlier Zen offerings and have decided to attach the input buffer from Zen 4 onto my ZV7-T.
My question: Do I just use the buffer transistor and associated bias and filtering components, or do I also require Zen 4's feedback loop?
Hope all is well with everyone.
John
I'm studying Nelson's earlier Zen offerings and have decided to attach the input buffer from Zen 4 onto my ZV7-T.
My question: Do I just use the buffer transistor and associated bias and filtering components, or do I also require Zen 4's feedback loop?
Hope all is well with everyone.
John
You can just use the buffer, but it's worth noting that if you
run feedback back to the input of the buffer you can use
much higher impedances on the feedback network.
If you are running feedback back to the output of the buffer
you will still need series resistance at the output of the buffer.
run feedback back to the input of the buffer you can use
much higher impedances on the feedback network.
If you are running feedback back to the output of the buffer
you will still need series resistance at the output of the buffer.
Thanks Nelson,
I'm drawn towards the idea of including the buffer in the feedback loop. Is is safe to cut and paste ZV4's front end and associated values to ZV7-T's gain Fet?
I realize that it's showing nerves of jello to ask that question; I should build it, plug it in and see what happens. It would be nice to avoid burning up another set of Fets, though. I've destroyed a half-dozen pairs so far.
I'm also planning to run the 47 ohm resistors from output to ground and swap the iron-core choke for air-core. Since this is a high-frequency amp (400hz and up), I can get away with smaller chokes.
This project is great fun, Nelson, and I can't thank you enough for your support of the BAMs out there (backyard-amp-mechanics). BAM is also what my amp sounds like when I let out the magic smoke...
John
I'm drawn towards the idea of including the buffer in the feedback loop. Is is safe to cut and paste ZV4's front end and associated values to ZV7-T's gain Fet?
I realize that it's showing nerves of jello to ask that question; I should build it, plug it in and see what happens. It would be nice to avoid burning up another set of Fets, though. I've destroyed a half-dozen pairs so far.
I'm also planning to run the 47 ohm resistors from output to ground and swap the iron-core choke for air-core. Since this is a high-frequency amp (400hz and up), I can get away with smaller chokes.
This project is great fun, Nelson, and I can't thank you enough for your support of the BAMs out there (backyard-amp-mechanics). BAM is also what my amp sounds like when I let out the magic smoke...
John
I've ordered 80lb. of 16AWG copper wire to fabricate the air-core chokes. I'm starting off with 50mH per leg since this amp is to be used over 400hz.
R-13 is my best guess. I'm a rank amateur at this stuff. Fabricating is what I do best.
I've ordered 100 IRFP044N transistors cause I want to hear what the little fellows sound like; this is why I lowered the input voltage, not to mention I run a 110 db horn from 400hz to 20k. I don't require 30 watts...
Right side of schematic is a mirror of left, hence no values entered.
I'll begin revamping my project this weekend.
John
R-13 is my best guess. I'm a rank amateur at this stuff. Fabricating is what I do best.
I've ordered 100 IRFP044N transistors cause I want to hear what the little fellows sound like; this is why I lowered the input voltage, not to mention I run a 110 db horn from 400hz to 20k. I don't require 30 watts...
Right side of schematic is a mirror of left, hence no values entered.
I'll begin revamping my project this weekend.
John
by the way...
I treated the ZVP3310 like a LED and biased it accordingly. Like I said previously, I'm just an amateur at this. I think Nelson is biasing this transistor at 8 mA, so I adjusted the bias resistor to the lowered 22.5v voltage to match the 8 mA figure.
This is so elementary to the EEs here, sorry...
John
I treated the ZVP3310 like a LED and biased it accordingly. Like I said previously, I'm just an amateur at this. I think Nelson is biasing this transistor at 8 mA, so I adjusted the bias resistor to the lowered 22.5v voltage to match the 8 mA figure.
This is so elementary to the EEs here, sorry...
John
Interesting...
I replaced the 1000V/A Plitron with a very small (in comparison) center-tapped, air-core choke. It weighs 6lb. and has an inductance of roughly 10mH per leg -- that's according to the coil winder's meter. It's resistance is about 1.6 ohms per leg.
The amp is bi-amped, operates the high frequency spectrum and is crossed over at 500hz.
It's late, no time for adjustments, just fired it up.
Observations:
The CCS transistor not only doesn't get hot, it doesn't even get warm. Humm? The gain transistors are slightly cooler than normal, but still warm up the chassis a bit -- they're easy to touch, though. The choke is mildly warm, not hot by any means.
I'm running the amp through my surround sound, center channel 2445 driver and horn. The driver is rated at 16ohms, 110 db. 1w1m.
The sound felt a bit rough at first but became sweeter as the amp warmed up. I hear less hash, it's a bit brighter...
All in all, this mod pleases me, and best of all, cost much less than a transformer. I spent $36.00 (US).
Again, my fondness for Nelson is further reinforced. I've learned a great deal from him and this forum. Thanks everyone.
John
I replaced the 1000V/A Plitron with a very small (in comparison) center-tapped, air-core choke. It weighs 6lb. and has an inductance of roughly 10mH per leg -- that's according to the coil winder's meter. It's resistance is about 1.6 ohms per leg.
The amp is bi-amped, operates the high frequency spectrum and is crossed over at 500hz.
It's late, no time for adjustments, just fired it up.
Observations:
The CCS transistor not only doesn't get hot, it doesn't even get warm. Humm? The gain transistors are slightly cooler than normal, but still warm up the chassis a bit -- they're easy to touch, though. The choke is mildly warm, not hot by any means.
I'm running the amp through my surround sound, center channel 2445 driver and horn. The driver is rated at 16ohms, 110 db. 1w1m.
The sound felt a bit rough at first but became sweeter as the amp warmed up. I hear less hash, it's a bit brighter...
All in all, this mod pleases me, and best of all, cost much less than a transformer. I spent $36.00 (US).
Again, my fondness for Nelson is further reinforced. I've learned a great deal from him and this forum. Thanks everyone.
John
Hi apassgear, hi flg!
I thought I was stuck somewhere out there in the twilight-zone. It's nice to hear from my diy pals. Although it's wonderful to hear from Nelson, you guys are just as important to me.
I'm gearing up to upgrade the ZV7-T this fall/winter. I've decided to begin with the air-core chokes, followed by the buffer and output to ground resistors. I'll be excited to report what transpires -- hopefully it will be excellent news.
Eventually, I want to figure out how to use the jfets that Rollin sold me to cascode to the gain fets -- a quieter buffer?
I'm studying electronics from the publications I have on hand. I'm gradually, like a snail in heat, trudging towards enlightenment. Ha! The problem with getting older is that I can't retain as well. Darn.........
Still, life is good.
John
I thought I was stuck somewhere out there in the twilight-zone. It's nice to hear from my diy pals. Although it's wonderful to hear from Nelson, you guys are just as important to me.
I'm gearing up to upgrade the ZV7-T this fall/winter. I've decided to begin with the air-core chokes, followed by the buffer and output to ground resistors. I'll be excited to report what transpires -- hopefully it will be excellent news.
Eventually, I want to figure out how to use the jfets that Rollin sold me to cascode to the gain fets -- a quieter buffer?
I'm studying electronics from the publications I have on hand. I'm gradually, like a snail in heat, trudging towards enlightenment. Ha! The problem with getting older is that I can't retain as well. Darn.........
Still, life is good.
John
The chokes are getting warm, now. You can touch them with ease, but I wouldn't call them "cool".
Here's where the amp is currently running:
Input voltage: 28.6v
gate of gain FET: 8.8v
source of gain FET: 4.3v
drain of gain FET: 23v
junction between CCS and R6: 2.9v
edit: almost forgot; dc offset cold 15mV, hot 3mV.
It looks like I'll be keeping the input voltage around 28 volts vs. 22.5v as drawn in my version of Nelson's schematic. The drains of the gain FETs are 23 volts -- nearly what I wanted as is. Can anybody see why I shouldn't be able to use IRSP044N transistors?
by for now,
John
Here's where the amp is currently running:
Input voltage: 28.6v
gate of gain FET: 8.8v
source of gain FET: 4.3v
drain of gain FET: 23v
junction between CCS and R6: 2.9v
edit: almost forgot; dc offset cold 15mV, hot 3mV.
It looks like I'll be keeping the input voltage around 28 volts vs. 22.5v as drawn in my version of Nelson's schematic. The drains of the gain FETs are 23 volts -- nearly what I wanted as is. Can anybody see why I shouldn't be able to use IRSP044N transistors?
by for now,
John
I gave my ZV7-T another listen tonight -- an hour of bliss.
The music included piano and cello. Both instruments were haunting in their delivery. The group: Pink Martini -- CD title: Hang on little tomato.
The high notes on the piano were clear, clean, and distinct -- much better than before, when I used the iron core inductor. The cello came across with such clarity -- very clean, lush.
The other day I said the amp sounded brighter... humm, not exactly, I'm not sure which adjective would be more appropriate. The sound is smooth, while being bright, yet it's not brittle.
Towards the end of the listening session, the amp had fully warmed up. This is where its warmth and luster blossomed. It has a great deal of character. I'm just amazed.
All this took place in digital "three way stereo" mode, just using L/R and center. Digital is not nearly as pretty sounding as standard analogue stereo mode. Somehow, this little Zen wades through the digital format without loosing it composure. Maybe it blends, softens. Whatever it's doing, I sure like it...
John
The music included piano and cello. Both instruments were haunting in their delivery. The group: Pink Martini -- CD title: Hang on little tomato.
The high notes on the piano were clear, clean, and distinct -- much better than before, when I used the iron core inductor. The cello came across with such clarity -- very clean, lush.
The other day I said the amp sounded brighter... humm, not exactly, I'm not sure which adjective would be more appropriate. The sound is smooth, while being bright, yet it's not brittle.
Towards the end of the listening session, the amp had fully warmed up. This is where its warmth and luster blossomed. It has a great deal of character. I'm just amazed.
All this took place in digital "three way stereo" mode, just using L/R and center. Digital is not nearly as pretty sounding as standard analogue stereo mode. Somehow, this little Zen wades through the digital format without loosing it composure. Maybe it blends, softens. Whatever it's doing, I sure like it...
John
Hi guys!
Apassgear, I believe that the bias voltage is located at the junction between the CCS and R6 -- 2.9 volts. I'm just learning so if I'm wrong here, I apologize in advance -- what I do is divide 2.9 volts by the power resistor's resistance which is 0.5 ohms. This yields 5.8 amps of bias for the gain transistors. What's amazing is that the CCS transistor doesn't get hot, it's barely warm.
Dennis, I use an online choke calculator. I practice a bit of moderation and use 14 gauge wire. You could use 12, but it takes a whole lot more. Going with 14 gauge, the calculator suggests for 2 times 80mH a bobbin that's 2 inches tall/wide (depending how you are looking at it) with an inner diameter of 1 inch and an outer diameter of 7.5 inches. Both legs are wound at the same time creating a center tap. This fellow has 2 ohms per leg. Hope this is useful.
edit: Dennis, I checked a chart -- 1600 feet of 14 gauge copper wire weighs about 20 lb. My inductors weigh 6 lb. Your inductor is going to be quite a bit larger than mine! Good luck with your adventure.
Nice chatting with you guys,
John
Apassgear, I believe that the bias voltage is located at the junction between the CCS and R6 -- 2.9 volts. I'm just learning so if I'm wrong here, I apologize in advance -- what I do is divide 2.9 volts by the power resistor's resistance which is 0.5 ohms. This yields 5.8 amps of bias for the gain transistors. What's amazing is that the CCS transistor doesn't get hot, it's barely warm.
Dennis, I use an online choke calculator. I practice a bit of moderation and use 14 gauge wire. You could use 12, but it takes a whole lot more. Going with 14 gauge, the calculator suggests for 2 times 80mH a bobbin that's 2 inches tall/wide (depending how you are looking at it) with an inner diameter of 1 inch and an outer diameter of 7.5 inches. Both legs are wound at the same time creating a center tap. This fellow has 2 ohms per leg. Hope this is useful.
edit: Dennis, I checked a chart -- 1600 feet of 14 gauge copper wire weighs about 20 lb. My inductors weigh 6 lb. Your inductor is going to be quite a bit larger than mine! Good luck with your adventure.
Nice chatting with you guys,
John
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.