Taramp 3k bass burnt power trace.
- By Soldersubohm
- Car Audio
- 4 Replies
Well I got this taramps 3k bass from a buddy said it was blown and I could have it. We'll checked none of the fets were shorted so I took out the board from the heat sink. Wow ...taramps need to move this brass bar they put on the trace closer to the terminal. I did because it burnt all the way through it. I wish I took a pic before I fixed it. But my question, do you think this fix will suffice or should I bridge the top of the board too?. And this 10ohm 20w resistor was cracked. After a closer look. It melted the caps ..although i think they wernt compromised. They look worse than they are. Do you think this is related to the power trace failure. The amp is working. Then I seen the resistor and seen all the heat that was generated.so i tore the caps and resistor out. I hope it was related. BTW this amp was probably hooked up with too small of wire and god knows what ohm load the speakers were wired at.. with the gain high. With no regard to what clipping is.. some people....thanks guys.
12V pure sine wave Inverter using op-amps.
- By mr_zener
- Power Supplies
- 35 Replies
HI all.
I want to make a inverter powered by a 12V wall-wart adapter to power valve heaters with the low side then drive a center-tapped mains transformer in reverse to get the high plate voltage.
Online I see mainly square wave drive designs, but I think this is a bad idea for a high gain valve preamp, so I set up a simulation.
I plan to use a XR2206 or ICL8038 for a basic sine wave generator.
I like the idea of using a sine inverter and can run the transformer at a higher frequency for easier filtering and adjust voltage by a potentiometer after the function generator IC.
This design outputs 130Vac. does this look like I'm on the right track?
I want to make a inverter powered by a 12V wall-wart adapter to power valve heaters with the low side then drive a center-tapped mains transformer in reverse to get the high plate voltage.
Online I see mainly square wave drive designs, but I think this is a bad idea for a high gain valve preamp, so I set up a simulation.
I plan to use a XR2206 or ICL8038 for a basic sine wave generator.
I like the idea of using a sine inverter and can run the transformer at a higher frequency for easier filtering and adjust voltage by a potentiometer after the function generator IC.
This design outputs 130Vac. does this look like I'm on the right track?
KEF 104/2 crossover caps
- By jeffrowland
- Multi-Way
- 11 Replies
I took the photo of the crossover in the topic Kef 104/2 tweeter replace...
I was asking the crossover experts if changing the values of 13 /14 /15 /16 caps and the resistors regarding the Tweeter power could also affect the performance of the two B200 woofers which are in push-pull mode?
thankyou
I was asking the crossover experts if changing the values of 13 /14 /15 /16 caps and the resistors regarding the Tweeter power could also affect the performance of the two B200 woofers which are in push-pull mode?
thankyou
TDA2050 amplifier board
- By Tube Radio
- Solid State
- 90 Replies
Needed a small amp to replace the underperforming amp for a speaker and found this.
https://www.amazon.com/HiLetgo-TDA2050-Amplifier-Digital-5W-120W/dp/B0CDWTL57H
Aside for a couple altered resistor values, the amp is the circuit shown in the datasheet.
https://www.st.com/resource/en/datasheet/cd00000131.pdf
The amp works good for what it is.
The plan is to use the second one for testing purposes to see just what this amp is capable of.
I'll do two things.
1. Use a 4 and 8 ohm load powering the amp at 24Vac with an audio generator supplying the signal and oscope across the load to see what the frequency response is and how much power it puts out.
2. Find the lowest resistance for R4 that keeps gain above 25dB (1dB higher than datasheet recommendation for safety) and the highest resistance value including R4 that keeps the amp stable while keeping a flat frequency response. I'll then use a fixed resistor to set the lowest gain and a trimpot in series. That way I'll have a variable gain.
I may also pick up two more of these amps and run them bridged to see if it's possible to eliminate the speaker coupling capacitor. That would limit me to an 8 ohm load though which will be fine. The phase splitter for testing will be an Edcor transformer with a 15k center tapped primary and secondary, however if the amp is proven successful I may either use a dual OP-AMP as a phase splitter or use the amp with balanced sources. The phase splitter could be built in a separate box with various inputs or I could use a balanced preamp if I actually decide to do anything with these amps at which time I'd add speaker protection as well given no speaker coupling caps.
https://www.amazon.com/HiLetgo-TDA2050-Amplifier-Digital-5W-120W/dp/B0CDWTL57H
Aside for a couple altered resistor values, the amp is the circuit shown in the datasheet.
https://www.st.com/resource/en/datasheet/cd00000131.pdf
The amp works good for what it is.
The plan is to use the second one for testing purposes to see just what this amp is capable of.
I'll do two things.
1. Use a 4 and 8 ohm load powering the amp at 24Vac with an audio generator supplying the signal and oscope across the load to see what the frequency response is and how much power it puts out.
2. Find the lowest resistance for R4 that keeps gain above 25dB (1dB higher than datasheet recommendation for safety) and the highest resistance value including R4 that keeps the amp stable while keeping a flat frequency response. I'll then use a fixed resistor to set the lowest gain and a trimpot in series. That way I'll have a variable gain.
I may also pick up two more of these amps and run them bridged to see if it's possible to eliminate the speaker coupling capacitor. That would limit me to an 8 ohm load though which will be fine. The phase splitter for testing will be an Edcor transformer with a 15k center tapped primary and secondary, however if the amp is proven successful I may either use a dual OP-AMP as a phase splitter or use the amp with balanced sources. The phase splitter could be built in a separate box with various inputs or I could use a balanced preamp if I actually decide to do anything with these amps at which time I'd add speaker protection as well given no speaker coupling caps.
ROAR18 - Large build and response measurements
- By Thijs666
- Subwoofers
- 17 Replies
Long story short:
7x ROAR18 with different drivers tested, measured, used at a DJ gig in a 500-person venue with impressive results.
Pros: Lots of headroom, especially in the kick range, usable up to 120 Hz and possibly higher.
Cons: Needs EQ in the low end for a balanced sound, big and maybe a bit too heavy for one man to throw around.
The long story:
A friend of mine wanted "decent" sound everywhere in his big barn where he works on his hobby (cars) and asked me for help. It didn't have to be very loud, but it's a big place, about 20 m x 10 m x 11 m (LxBxH), so a single sub wasn't going to cut it. Knowing his taste in music a little, I knew he wasn't necessarily looking for the lowest possible notes, but a tight kick was definitely needed. Instead of designing something from scratch, I thought Martinsson's ROAR18 might do the trick. This was helped by the fact that I had already built and listened to the ROAR15 just to see how it would sound. Although it didn't get very loud in the low end, it responded pretty well to EQ at the expense of max SPL (40Hz was certainly doable).
The ROAR18 seemed to dig a little deeper on paper, especially with a small "mod" that I did: use ALL the internal volume available (so the long channel is about 10 cm longer; this seemed to simulate fine: a bit less sensitivity in return for a little lower response). So I figured it would also do well with some rap music (also a prerequisite). And another big factor was that I had a couple of different 18's lying around, plus a bunch of broken and discarded 18's at work, where I was happy to pull them out of the trash (with permission)! They were Celestion CF1840JD's that needed their magnets realigned as the glue had failed, so it was quite an operation with a few recones involved.
They were not the best for the ROAR18 (not the biggest BL), but they simulated ok. So I decided to build a ROAR18 to evaluate. After listening to it, my friend approved and I set out to build 6 more, since that number matched the cut list of 15 sheets of plywood (244x122 cm) and the number of 18's I had on hand; hence the odd "7".
First one built:
In-room measurements with and without EQ:
The large build:
With wood prices through the roof, I opted for cheap underlays (32 Euro/sheet) because they were for a permanent installation and didn't need to be "road proof". The three that were for me (the white ones in the photos) I laminated with epoxy/fiberglass. These latter ones had wheels and weighed a whopping 84 kg.
I finished them a few weeks ago and asked another friend of mine at a place called "Landbouwbelang" in Maastricht, the Netherlands, if I could measure them there since they have an outdoor space with little interference from nearby walls and such. He went one better and asked me if I would like to try them out at a party that was going to take place there in two weeks. Yes, of course!
Measurements were taken at 2.83 V, no filters or EQ, with the mic at 1 m on the ground and the speaker facing the river, see photos. Everything seemed fine, although the 109 dB/W at 106 Hz seemed a bit high to me, but I double-checked my measurements and levels...
The drivers are:
-5x Celestion CF1840JD (8 Ohm 1200 W RMS/2400 W program)
-1x Celestion CF18VJD (8 Ohm 1600 W RMS/3200 W program)
-1x Beyma 18P80Nd (8 Ohm 800 W RMS/1600 W program)
The measurements were done with Umik-1 and REW V5.20.13.
I think the measurements and photos speak for themselves 😊.
The gig:
(left and right of my setup are the in-house system speakers, Xtro + 186 Horn)
The setup for the gig was as follows:
1x Nova DC8000 processor
2x Powersoft D4002 bridged to 2x CF1840JD subs on left and right stereo channels, delayed to 45 cm -> 4000 W into 4 ohms (these are the black subs on both ends in the show setup)
1x Powersoft M50Q channels 1 and 2 bridged to the CF18VJD sub and channels 3 and 4 bridged to the 5th CF1840JD -> 2x 2500 W at 8 ohms (both mono summed)
1x Powersoft D2002 bridged to the Beyma 18P80Nd sub -> 1x 1200 W at 8 ohms (mono summed)
1x RAM Audio S6004 for my Synergy tops (build link here: https://www.diyaudio.com/community/threads/synergy-horn-for-135-db.305852/) -> 2x 1480 W into 4 ohms.
The HP for the Roars was set at 27 Hz and 48 dB/oct. I set the LP quite high at 120 Hz and 48 dB/oct because I wanted to hear how they would handle kick and sub duties.
I used a 6 dB low shelf at 50 Hz with 6 dB gain and a 3 dB bump at 40 Hz with a Q of 2.871 (or 0.5 octaves). To even out the room modes, I delayed the outer 4 subs by 1.31 ms (or 45 cm), which gave a nice even sound throughout the venue. The limiters were set conservatively on RMS, but allowed peaks to get through.
The headroom was kind of absurd (at least in my book), which is of course a good thing: all night long the -9dB lights on the amps were occasionally tickled, only during the VERY LAST song they turned it up to -6 dB peaks, which was still enjoyable, but not for much more than one or two songs.
There were many compliments on the quality and amount of bass, and apparently it was much more powerful than the in-house system consisting of two XTro tops and four 186 horn subs. I was also pleasantly surprised with my 2" Synergy horns, they easily kept up!
Here is a playlist with a few videos taken with my phone:
https://www.youtube.com/playlist?list=PLZ9IxQRaHpo8qlY31TOXkLRJ4tjH5XnTm
Now I have to figure out where to place the subs in this big barn I built them for in the first place...
But maybe there will be another gig before they are permanently installed😎.
Any questions, remarks, comments, suggestions, let me know 🙂
7x ROAR18 with different drivers tested, measured, used at a DJ gig in a 500-person venue with impressive results.
Pros: Lots of headroom, especially in the kick range, usable up to 120 Hz and possibly higher.
Cons: Needs EQ in the low end for a balanced sound, big and maybe a bit too heavy for one man to throw around.
The long story:
A friend of mine wanted "decent" sound everywhere in his big barn where he works on his hobby (cars) and asked me for help. It didn't have to be very loud, but it's a big place, about 20 m x 10 m x 11 m (LxBxH), so a single sub wasn't going to cut it. Knowing his taste in music a little, I knew he wasn't necessarily looking for the lowest possible notes, but a tight kick was definitely needed. Instead of designing something from scratch, I thought Martinsson's ROAR18 might do the trick. This was helped by the fact that I had already built and listened to the ROAR15 just to see how it would sound. Although it didn't get very loud in the low end, it responded pretty well to EQ at the expense of max SPL (40Hz was certainly doable).
The ROAR18 seemed to dig a little deeper on paper, especially with a small "mod" that I did: use ALL the internal volume available (so the long channel is about 10 cm longer; this seemed to simulate fine: a bit less sensitivity in return for a little lower response). So I figured it would also do well with some rap music (also a prerequisite). And another big factor was that I had a couple of different 18's lying around, plus a bunch of broken and discarded 18's at work, where I was happy to pull them out of the trash (with permission)! They were Celestion CF1840JD's that needed their magnets realigned as the glue had failed, so it was quite an operation with a few recones involved.
They were not the best for the ROAR18 (not the biggest BL), but they simulated ok. So I decided to build a ROAR18 to evaluate. After listening to it, my friend approved and I set out to build 6 more, since that number matched the cut list of 15 sheets of plywood (244x122 cm) and the number of 18's I had on hand; hence the odd "7".
First one built:
In-room measurements with and without EQ:
The large build:
With wood prices through the roof, I opted for cheap underlays (32 Euro/sheet) because they were for a permanent installation and didn't need to be "road proof". The three that were for me (the white ones in the photos) I laminated with epoxy/fiberglass. These latter ones had wheels and weighed a whopping 84 kg.
I finished them a few weeks ago and asked another friend of mine at a place called "Landbouwbelang" in Maastricht, the Netherlands, if I could measure them there since they have an outdoor space with little interference from nearby walls and such. He went one better and asked me if I would like to try them out at a party that was going to take place there in two weeks. Yes, of course!
Measurements were taken at 2.83 V, no filters or EQ, with the mic at 1 m on the ground and the speaker facing the river, see photos. Everything seemed fine, although the 109 dB/W at 106 Hz seemed a bit high to me, but I double-checked my measurements and levels...
The drivers are:
-5x Celestion CF1840JD (8 Ohm 1200 W RMS/2400 W program)
-1x Celestion CF18VJD (8 Ohm 1600 W RMS/3200 W program)
-1x Beyma 18P80Nd (8 Ohm 800 W RMS/1600 W program)
The measurements were done with Umik-1 and REW V5.20.13.
I think the measurements and photos speak for themselves 😊.
The gig:
(left and right of my setup are the in-house system speakers, Xtro + 186 Horn)
The setup for the gig was as follows:
1x Nova DC8000 processor
2x Powersoft D4002 bridged to 2x CF1840JD subs on left and right stereo channels, delayed to 45 cm -> 4000 W into 4 ohms (these are the black subs on both ends in the show setup)
1x Powersoft M50Q channels 1 and 2 bridged to the CF18VJD sub and channels 3 and 4 bridged to the 5th CF1840JD -> 2x 2500 W at 8 ohms (both mono summed)
1x Powersoft D2002 bridged to the Beyma 18P80Nd sub -> 1x 1200 W at 8 ohms (mono summed)
1x RAM Audio S6004 for my Synergy tops (build link here: https://www.diyaudio.com/community/threads/synergy-horn-for-135-db.305852/) -> 2x 1480 W into 4 ohms.
The HP for the Roars was set at 27 Hz and 48 dB/oct. I set the LP quite high at 120 Hz and 48 dB/oct because I wanted to hear how they would handle kick and sub duties.
I used a 6 dB low shelf at 50 Hz with 6 dB gain and a 3 dB bump at 40 Hz with a Q of 2.871 (or 0.5 octaves). To even out the room modes, I delayed the outer 4 subs by 1.31 ms (or 45 cm), which gave a nice even sound throughout the venue. The limiters were set conservatively on RMS, but allowed peaks to get through.
The headroom was kind of absurd (at least in my book), which is of course a good thing: all night long the -9dB lights on the amps were occasionally tickled, only during the VERY LAST song they turned it up to -6 dB peaks, which was still enjoyable, but not for much more than one or two songs.
There were many compliments on the quality and amount of bass, and apparently it was much more powerful than the in-house system consisting of two XTro tops and four 186 horn subs. I was also pleasantly surprised with my 2" Synergy horns, they easily kept up!
Here is a playlist with a few videos taken with my phone:
https://www.youtube.com/playlist?list=PLZ9IxQRaHpo8qlY31TOXkLRJ4tjH5XnTm
Now I have to figure out where to place the subs in this big barn I built them for in the first place...
But maybe there will be another gig before they are permanently installed😎.
Any questions, remarks, comments, suggestions, let me know 🙂
Eton Woofers construction problem!
Dear DIY People,
“Just” as info :
I noticed some construction problems in some Eton 7-375/32 HEX (in 2013-2014, I thought it’s a "casual" thing!) and then again I have the same problem in 2018-2020 with some Symphony II 7-312/C8/32 HEX!
The wires connection that goes from the terminals to the coil hits the cone during excursion.
We can mainly notice it when the woofer reproduce continuos low frequencies with excursions of +-2mm or more, and it's not just a question of "noise", it brings also to higher distortion.
Incredible to believe that we can have such a basic mistake on this price point drivers (over 200,00€ per piece),
NOT necessarily all drivers have this problem! Some does (more or less pronounced) some don't. Question of luck.
ALL DEPENDS on how "carefully" they glued the wire to the cone! Above the glue point the cable is very close to the cone.
I guess they should have found a better solution that it's not so sensitive to human error.
I will try to attach 1 photo and a Video (at the end of the page). In the videos is clearly possible to see-hear what I mean.
The test was made at 30, 35, 40 and 45 Hz, and I did the same test with drivers of the cost of 20,00/40,00€ values and there was no any noise! 🙁
But it’s enough to play records like the Billie Eilish one and you will clearly ear it…
P.S.
I wrote many email to Eton, just to share my experience and to "help" them for the future... NEVER any kind of answer.
I also wrote few times to Klang&Ton and to Mr. Holger Barske (email and Facebook) thought that they should be interested on this kind of concern... NEVER any kind of answer. 🙁
View attachment Eton 7-312-C8-32HEX-Video-CutSm.mp4
Thank you for the attention!
Take care and great DIY building to all of you!
Andrea
“Just” as info :
I noticed some construction problems in some Eton 7-375/32 HEX (in 2013-2014, I thought it’s a "casual" thing!) and then again I have the same problem in 2018-2020 with some Symphony II 7-312/C8/32 HEX!
The wires connection that goes from the terminals to the coil hits the cone during excursion.
We can mainly notice it when the woofer reproduce continuos low frequencies with excursions of +-2mm or more, and it's not just a question of "noise", it brings also to higher distortion.
Incredible to believe that we can have such a basic mistake on this price point drivers (over 200,00€ per piece),
NOT necessarily all drivers have this problem! Some does (more or less pronounced) some don't. Question of luck.
ALL DEPENDS on how "carefully" they glued the wire to the cone! Above the glue point the cable is very close to the cone.
I guess they should have found a better solution that it's not so sensitive to human error.
I will try to attach 1 photo and a Video (at the end of the page). In the videos is clearly possible to see-hear what I mean.
The test was made at 30, 35, 40 and 45 Hz, and I did the same test with drivers of the cost of 20,00/40,00€ values and there was no any noise! 🙁
But it’s enough to play records like the Billie Eilish one and you will clearly ear it…
P.S.
I wrote many email to Eton, just to share my experience and to "help" them for the future... NEVER any kind of answer.
I also wrote few times to Klang&Ton and to Mr. Holger Barske (email and Facebook) thought that they should be interested on this kind of concern... NEVER any kind of answer. 🙁
View attachment Eton 7-312-C8-32HEX-Video-CutSm.mp4
Thank you for the attention!
Take care and great DIY building to all of you!
Andrea
15 Watt Class A with EXICON Lateral MOSFETs - John Linsley Hood style
- By lineup
- Solid State
- 7 Replies
Hello there amplifier lovers! 🙂
Here is the JLH Original:
Here is my suggested circuit with EXICON Laterals:
The power supply should use Transformer 2x15VAC
which gives around 40VDC after rectifier.
Here is the JLH Original:
Here is my suggested circuit with EXICON Laterals:
The power supply should use Transformer 2x15VAC
which gives around 40VDC after rectifier.
Show your outdoor / fun loudspeakers
- By Freedom666
- Multi-Way
- 49 Replies
I think the time has come we have to show our fun loudspeakers or outdoor ones.
Here my contribution (outdoor fun speaker) :
Cheapo drivers with diy aluminium sandwich cones. (there is a thread on it here on diy audio forum).
DIY whizzer cone and extra bass with 1mh inductivity forming a one and a half way system (=fullrange with added bass).
Cheapo TDA7498 amp with 34 Volt smps power supply. And whuzi audio preamp Bluetooth
with certainly only fake parts. But works.
Simple EQ with smartphone app.
Drivers were only 10 dollars but decent quality if you know how to use it.
Here my contribution (outdoor fun speaker) :
Cheapo drivers with diy aluminium sandwich cones. (there is a thread on it here on diy audio forum).
DIY whizzer cone and extra bass with 1mh inductivity forming a one and a half way system (=fullrange with added bass).
Cheapo TDA7498 amp with 34 Volt smps power supply. And whuzi audio preamp Bluetooth
with certainly only fake parts. But works.
Simple EQ with smartphone app.
Drivers were only 10 dollars but decent quality if you know how to use it.
Attachments
Digging through the closet
- By bobgroger
- Tubes / Valves
- 1 Replies
Now that I am retired I am hoping to finish projects and move them on before my family has to. I dug these out, built them 25-ish years ago. Mostly the Andrea Ciuffoli OTL v8.2 with a few changes to fit the transformers I had. Operating at 150v/200ma -52-ish v bias. 44W at clipping, the driver stage clips first. An ambitious project at the time, 5 total transformers. I am going to modify to a SRPP first stage based on the tubedvr design.
Attachments
For Sale Zilchlab Econowave Crossover PCBs
- By wiredbecker
- Swap Meet
- 89 Replies
FS: Zilchlab Econowave Crossover PCBs
Before Zilch passed away he asked me to keep these crossover boards available and in consistent production for speaker builders everywhere. Pairs are available direct from me for $32 shipped CONUS w/instructions. Send me a PM if you'd like to build a pair of Zilch's Econowave speakers.
For more specific build information check out the massive original thread here on Audiokarma: Zilch's AK Design Collaborative - Econowave Speaker | Audiokarma Home Audio Stereo Discussion Forums
Not to mention Flex Your PCD Mettle on the Parts Express site where he really picked up steam: Flex Your PCD Mettle: - Techtalk Speaker Building, Audio, Video Discussion Forum
Before Zilch passed away he asked me to keep these crossover boards available and in consistent production for speaker builders everywhere. Pairs are available direct from me for $32 shipped CONUS w/instructions. Send me a PM if you'd like to build a pair of Zilch's Econowave speakers.
For more specific build information check out the massive original thread here on Audiokarma: Zilch's AK Design Collaborative - Econowave Speaker | Audiokarma Home Audio Stereo Discussion Forums
Not to mention Flex Your PCD Mettle on the Parts Express site where he really picked up steam: Flex Your PCD Mettle: - Techtalk Speaker Building, Audio, Video Discussion Forum
Attachments
Neurochrome Preamp Power Supply and Universal Buffer
Neurochrome Preamp Power Supply. SOLD
Neurochrome Universal Buffer. SOLD
These are like Swiss Army Knives. Super versatile. Used for a while in a preamp and now they just sit on a shelf.
Neurochrome Universal Buffer. SOLD
These are like Swiss Army Knives. Super versatile. Used for a while in a preamp and now they just sit on a shelf.
For Sale 2x SB Audience ROSSO 12MW300 Midwoofer
Attachments
-
eyJidWNrZXQiOiJtZWRpYS5hZHNpbWcuY29tIiwia2V5IjoiY2E4YmQyZGExMTYwMjkwNjBmZjliZTY5YTdlM2E4ZDMyMT...jpg -
eyJidWNrZXQiOiJtZWRpYS5hZHNpbWcuY29tIiwia2V5IjoiZGFmYjc5YzlhY2E4NDA3OWQ0YzUxMzEyZGEzZjcyZTdlN...jpeg -
eyJidWNrZXQiOiJtZWRpYS5hZHNpbWcuY29tIiwia2V5IjoiZjk2NTJkMGNlZjdkMzg5ZTAxYjdlZmQxODJhMjFlNjkxZ...jpeg
DUAL CV40 phono input - load modification
- By Martin671
- Analog Line Level
- 6 Replies
Hello - I'm restoring a Dual CV40 amp to use with a Shure M95 G-LM cartridge (requires 47k input load).
I have a question regarding the modification of the resistive input load in the phono preamp (schematic attached).
If I understand correctly, in the set up shown, the signal sees the resistive load formed by the series resistor R2 and the parallel network of R1, R3+R8 (1.5k + approx 77k) - is this correct?
If I wanted to bring the load down to approx 47kohm, changing R1 to approx 53k should do the job?
Thanks in advance for your help!
Martin
I have a question regarding the modification of the resistive input load in the phono preamp (schematic attached).
If I understand correctly, in the set up shown, the signal sees the resistive load formed by the series resistor R2 and the parallel network of R1, R3+R8 (1.5k + approx 77k) - is this correct?
If I wanted to bring the load down to approx 47kohm, changing R1 to approx 53k should do the job?
Thanks in advance for your help!
Martin
Completed Aleph J boards (diyAudio store boards) - $50 plus shipping
- By lehmanhill
- Swap Meet
- 2 Replies
Attachments
1949 electronic sackbut 6as6 subcircuit
- Tubes / Valves
- 9 Replies
Hi diyaudio!
it's been a while since I've posted but I was wondering if any of you might be able to chime in on my latest research project.
Last time I was writing here I was looking for help on a hi fi amp i was building for my undergrad senior thesis. A few moves and thirteen years later I'm now a researcher at the Canadian museum of science and technology working to reverse engineer Hugh Le Caine's electronic sackbut instrument, which is part of their collection.
https://en.wikipedia.org/wiki/Electronic_sackbut#
My circuit analysis friend and I are a little stumped by the suggestion of a colleague that the 6as6 tubes in the oscillator section of the device are frequency counters: no feedback, no RC circuit with a time constant to flip flop a square wave at a defined rate. Just resistors:
I'm including two of the four stages. the caps on the left of the 6as6 stages go to a transformer coupled blocking oscillator. The output exiting left of the plate goes to a mixer-so the stages don't cascade. I really think this is just a buffer / gain stage to couple the aforementioned blocking oscillator to the strange resistive mixer that follows these pentodes.
I realize this is more of an amp forum than a synth forum, but since these pentodes really do look like a coupling stage to me (rather than a counter stage) I think we are squarely in the amplifier section of the tube circuit topology realm.
In short though - is there any conceivable way a pentode, wired like this or something like this (the circuit tracer may have missed something!) could act as a clock divider (e.g. take a square wave and output other square waves at ratios of the original frequency)?
Thanks in advance for your perspective, and let me know if there's additional info you might like to answer this more accurately!
it's been a while since I've posted but I was wondering if any of you might be able to chime in on my latest research project.
Last time I was writing here I was looking for help on a hi fi amp i was building for my undergrad senior thesis. A few moves and thirteen years later I'm now a researcher at the Canadian museum of science and technology working to reverse engineer Hugh Le Caine's electronic sackbut instrument, which is part of their collection.
https://en.wikipedia.org/wiki/Electronic_sackbut#
My circuit analysis friend and I are a little stumped by the suggestion of a colleague that the 6as6 tubes in the oscillator section of the device are frequency counters: no feedback, no RC circuit with a time constant to flip flop a square wave at a defined rate. Just resistors:
I'm including two of the four stages. the caps on the left of the 6as6 stages go to a transformer coupled blocking oscillator. The output exiting left of the plate goes to a mixer-so the stages don't cascade. I really think this is just a buffer / gain stage to couple the aforementioned blocking oscillator to the strange resistive mixer that follows these pentodes.
I realize this is more of an amp forum than a synth forum, but since these pentodes really do look like a coupling stage to me (rather than a counter stage) I think we are squarely in the amplifier section of the tube circuit topology realm.
In short though - is there any conceivable way a pentode, wired like this or something like this (the circuit tracer may have missed something!) could act as a clock divider (e.g. take a square wave and output other square waves at ratios of the original frequency)?
Thanks in advance for your perspective, and let me know if there's additional info you might like to answer this more accurately!
DC Heater buzz in series connected tube heaters
- By ronenash
- Tubes / Valves
- 11 Replies
Hi all,
I am trying to modify the attached circuit to use two parallel section of a 6922 tube for the gain stage instead of the 6GK5 while keeping the second 6GK5 cathode follower. In a previous version of this mod I had the two parallel section of the 6922 followed by a mosfet buffer and all worked fine.
The heaters are 12.6 DC regulated DC heaters with the tube connected in parallel. The original circuit had the two heaters for the 6gk5 on each channels connected in series. With the first tube a 6922 I can no longer do this as the 6922 and 6gk5 heater have different impedances and thus the voltage on each heater will not be the same. I modified the heater supply to feed two 6922 in series and the two 6gk5 heaters in series. both of these are connected in parallel to the 12.6v regulated supply. In doing so I am getting a high buzz on the output of the preamp. Music is playing and it looks like the voltages measure OK but the buzzing is very high. Any idea what's going on?
Thanks,
Ron
I am trying to modify the attached circuit to use two parallel section of a 6922 tube for the gain stage instead of the 6GK5 while keeping the second 6GK5 cathode follower. In a previous version of this mod I had the two parallel section of the 6922 followed by a mosfet buffer and all worked fine.
The heaters are 12.6 DC regulated DC heaters with the tube connected in parallel. The original circuit had the two heaters for the 6gk5 on each channels connected in series. With the first tube a 6922 I can no longer do this as the 6922 and 6gk5 heater have different impedances and thus the voltage on each heater will not be the same. I modified the heater supply to feed two 6922 in series and the two 6gk5 heaters in series. both of these are connected in parallel to the 12.6v regulated supply. In doing so I am getting a high buzz on the output of the preamp. Music is playing and it looks like the voltages measure OK but the buzzing is very high. Any idea what's going on?
Thanks,
Ron
Sugden Connoisseur speaker. More from the Yorkshire Triangle!
Bought a pair of these yesterday. Looking forward to restoring them. Having said that, they seem in very good condition. Does anybody have any information of these. When were they made, driver set up...? The 'condenser' I can see has '1943' on it. Surely, this isn't the date the speakers were made?
Tracking preregulator circuit LM317
- By Julian RO
- Power Supplies
- 18 Replies
I want to build this circuit. My question is, are the two protection diodes no longer needed?
Thank you in advance for your answers.
Thank you in advance for your answers.
For Sale Resistor groupings and some silver wire
- By mattattnet
- Swap Meet
- 3 Replies
Here are a few groups of things hopefully someone can find use for. Each group / item is priced individually with USA shipping included. I will give a shipping discount for multiple items purchased.
1) Twelve 25 or 50 watt wire wound aluminum chassis mount power resistors. If you cannot read the values, let me know.Asking $20 shipped.
2) Twelve Tantalum resistors, older Audio Note and Shinko: 1/2 watt: two @ 390R, two @ 1K. 2 watt: two @ 47K, two @ 100K, four @ 300K,asking $20 shipped. SOLD
3) Large cement 8 ohm leaded dummy load, 6 1/2 x 1 1/2 inches. 100W free air, 200W sinked.Asking $10 shipped.
4) Sixty older Kiwame japanese carbon film resistors, good to at least 750 volts. 46 @ 2 watts, 14 @ 5 watts, if you need a list of values, let me know via PM.Asking $50 shipped. SOLD
5) 4 or 5 - nines silver wire remnants with 20 gauge insulation tubing included: 4 ft. of 24 ga mundorf gold/silver alloy, 7 ft. of 24 ga, 4 ft of 20 ga. Also a spool of over 50 feet of 30 ga teflon coated instrumentation wire that now goes for 8$ a foot....Asking $50 shipped. SOLD
payment via Zelle or Paypal.
USA Shipping only.
1) Twelve 25 or 50 watt wire wound aluminum chassis mount power resistors. If you cannot read the values, let me know.
2) Twelve Tantalum resistors, older Audio Note and Shinko: 1/2 watt: two @ 390R, two @ 1K. 2 watt: two @ 47K, two @ 100K, four @ 300K,
3) Large cement 8 ohm leaded dummy load, 6 1/2 x 1 1/2 inches. 100W free air, 200W sinked.
4) Sixty older Kiwame japanese carbon film resistors, good to at least 750 volts. 46 @ 2 watts, 14 @ 5 watts, if you need a list of values, let me know via PM.
5) 4 or 5 - nines silver wire remnants with 20 gauge insulation tubing included: 4 ft. of 24 ga mundorf gold/silver alloy, 7 ft. of 24 ga, 4 ft of 20 ga. Also a spool of over 50 feet of 30 ga teflon coated instrumentation wire that now goes for 8$ a foot....
payment via Zelle or Paypal.
USA Shipping only.
Breathe new life into old Line 6 L3T Speaker?
- By guitylerham
- Multi-Way
- 1 Replies
Howdy!
I recently acquired this non-functioning PA cabinet that I've heard awesome reviews about but have no way of using. After a deep dive into plate amps and DSP, I've decided to see if I can use a Fusion FA253 (250w, 250w, 100w triamp) to power this MTM 2.5-way cabinet. One of the two identical Celestion midbass TF1020's gets a lowpass at 250hz, the second one gets passed at maybe 2kh and the 1" horn picks up the rest. I'm jumping off the deepend but I think I have the gumption to learn how to measure response and EQ with REW and the DSP onboard the Fusion amp. I'll be using this for simple live solo gigs with guitar, vocals, and some low bass and kick percusion (one-man band) and am hoping I can make this thing useable.
As it is, it's obviously been designed to be midbass/top and to be paired with a sub if needed. My options forward feel like either:
A) return this cabinet to it's original internal volume and don't touch anything else. Design the crossovers/EQ to mimic what I believe to be the original specs.
or
B) modifiy this cabinet/porting to lower the frequency range as much as I realistially can and design the crossovers/EQ anyway, new drivers (lightweiht neos maybe?).
I've been trying to figure out what I can do with this size of cabinet. A rough measurement yields about 1.25cuFt internal volume after accounting for driver displacement/internal baffles/hardware. The depth of the enclosure will limit the depth of the port so that is a hard limit. My assumption is that Line 6 did a great job of designing this but they may have also limited it due to costs and or wanting to position it within their product line to be paired with additional subs and boxes. I'm just wondering if there's value in working within this canvas and eeking out more performance (in exchange for SPL, I'm guessing) or just going with what's already been done.
I'll be building and glueing in a sealed compartment where the plate amp will be housed (the original plate amp is not the same frootprint so I can't use the original cast insert unfortunately).
Is this absolutely silly? I've already bought the new plate amp and am comitted but I'm also handy with tools and could use this amp in a new build. I just really want to use this form factor and see what it could offer. Thoughts?
Here's a link to the original manual (product is now discontinued, btw)
https://line6.com/data/6/0a06434d11...e6 L3t Specifications - English ( Rev A ).pdf
I recently acquired this non-functioning PA cabinet that I've heard awesome reviews about but have no way of using. After a deep dive into plate amps and DSP, I've decided to see if I can use a Fusion FA253 (250w, 250w, 100w triamp) to power this MTM 2.5-way cabinet. One of the two identical Celestion midbass TF1020's gets a lowpass at 250hz, the second one gets passed at maybe 2kh and the 1" horn picks up the rest. I'm jumping off the deepend but I think I have the gumption to learn how to measure response and EQ with REW and the DSP onboard the Fusion amp. I'll be using this for simple live solo gigs with guitar, vocals, and some low bass and kick percusion (one-man band) and am hoping I can make this thing useable.
As it is, it's obviously been designed to be midbass/top and to be paired with a sub if needed. My options forward feel like either:
A) return this cabinet to it's original internal volume and don't touch anything else. Design the crossovers/EQ to mimic what I believe to be the original specs.
or
B) modifiy this cabinet/porting to lower the frequency range as much as I realistially can and design the crossovers/EQ anyway, new drivers (lightweiht neos maybe?).
I've been trying to figure out what I can do with this size of cabinet. A rough measurement yields about 1.25cuFt internal volume after accounting for driver displacement/internal baffles/hardware. The depth of the enclosure will limit the depth of the port so that is a hard limit. My assumption is that Line 6 did a great job of designing this but they may have also limited it due to costs and or wanting to position it within their product line to be paired with additional subs and boxes. I'm just wondering if there's value in working within this canvas and eeking out more performance (in exchange for SPL, I'm guessing) or just going with what's already been done.
I'll be building and glueing in a sealed compartment where the plate amp will be housed (the original plate amp is not the same frootprint so I can't use the original cast insert unfortunately).
Is this absolutely silly? I've already bought the new plate amp and am comitted but I'm also handy with tools and could use this amp in a new build. I just really want to use this form factor and see what it could offer. Thoughts?
Here's a link to the original manual (product is now discontinued, btw)
https://line6.com/data/6/0a06434d11...e6 L3t Specifications - English ( Rev A ).pdf
AU-919 Low Volume Distortion
- By Dolamike
- Solid State
- 19 Replies
Hello all, I have a curious issue I am wondering if anyone here has advice or a solution.
I am finishing the restoration of a Sansui AU-919, recap, removal of problematic black flag capacitors, etc. The amp is finished and working, powers up, comes out of protect, bias and offset on the amplifier working.
I have low volume distortion that I have narrowed down to the flat amp / tone control board that disapears when the volume is turned up. I have been chasing my tail trying to find the issue... there are DC Offset trimmers on this board. When set to 0V DC the distortion is present, when I tweak the offset to allow for 50-60 mv of DC the distortion goes away. I'm wondering if this might be a lack of power to some of the transistors that is keeping them from turning on...
Schematic of this board below. Any ideas greatly appreciated. Thank you!
I am finishing the restoration of a Sansui AU-919, recap, removal of problematic black flag capacitors, etc. The amp is finished and working, powers up, comes out of protect, bias and offset on the amplifier working.
I have low volume distortion that I have narrowed down to the flat amp / tone control board that disapears when the volume is turned up. I have been chasing my tail trying to find the issue... there are DC Offset trimmers on this board. When set to 0V DC the distortion is present, when I tweak the offset to allow for 50-60 mv of DC the distortion goes away. I'm wondering if this might be a lack of power to some of the transistors that is keeping them from turning on...
Schematic of this board below. Any ideas greatly appreciated. Thank you!
Audio Research D-100B restoration
- By tubenut99
- Solid State
- 0 Replies
I decided to start a new thread on this amp as the other thread dealt mainly with replacing the AM-1, AM-2 sealed predriver modules.
So going back, I received this unit knowing that the owner mentioned it got wacked with over 130VAC during a storm and a power surge.
It took out all 4 front 6 amp fuses for the -50,+50 supply . He had someone look at it and some output transistors were blown on the right channel and then it was never finished and sat for 10 years. So I thought I would take a chance and see if I could repair it. As I mainly repair tube gear, I haven't really worked on any SS amps with this many transistors in it.
Not sure if anyone is familiar with this unit, it has a massive power transformer and caps creating -50, +50 for the power transistors and also feeding back to the predriver board and also +75, -75 volts also feeding the predriver board. Taking the power module apart is quite a task in these amps. You have to unscrew the predriver module( more on that later) , then there are 4 PC board which are soldered and have to be removed before getting access to the power output transistors. Then you have to unscrew each heatsink for 3 transistors.
Each channel has a pair of NPN feeding 4 PNP(-50) and then 2 PNP feeding 4 NPN (+50). The right far bank had 2 transistors removed (which had been worked on), and in a bag came with a few more NPN predrivers and a blown PNP and some screws.
So what I really should of done was just order all new transistors from Mouser/DigiKey On semi makes them. The part #'s on the original transistors are AR part numbers and here are their equivalents for reference.
300024(NPN) MJ15015
300025(PNP) MJ15016
300027(PNP)MJ15004
300028(NPN)MJ15005
There are total of 24 transistors in the power section of this amp. My mistake was to look for and shorted or out of spec transistors and replaced them. As only having a cheap transistor checker I got them as close as I could matched (hfe) and there were no shorts and more. I then got reading that a lot of issues were caused by the predriver board.
The predriver board consists of 2 sealed AM-1, AM-2 IC type modules which have quite a few transistors in it and cannot be purchased any more. One fellow on another thread(repairing the AR 110 modules) has designed some replacement modules to replace the AM-1, AM-2 units.
I verified that mine were ok and I had signal through both. After fixing the bad transistors I fired the unit up slowly on a variac and no shorts or smoke and voltages were ok.
I had gain in both channels . The left seemed a bit bit lower but with a 1kHz signal across a 100 watt 8ohm load , I scoped the outputs and sine wave looked good, but I had some neg DC offset, meaning some DC was leaking onto the speaker terminals. In some amps there are gain and DC offset controls to adjust this, but in these amps there are none.
Reading more, the DC offset in the output is most likely caused by mismatched transistors, or in reading the other post some of those AM-1. AM-2 modules could cause the neg offset.
I went over the output section again replacing a few more transistors and then somehow turning it back on I was getting the full -50v on the output. It looked like a short somewhere.
Well pulling my hair out I decided to replace all the outputs and now I have less than 20mv on each channel. One or more of the original transistors must of have been bad and not picked up by the tester until full DC power was applied to the output.
I have attached the schematics. I am now in the process of working on the predriver board with the new boards that another member designed.
I will continue this later, hopefully this helps someone else.You can get bigger versions of these schematics from the AR site.
So going back, I received this unit knowing that the owner mentioned it got wacked with over 130VAC during a storm and a power surge.
It took out all 4 front 6 amp fuses for the -50,+50 supply . He had someone look at it and some output transistors were blown on the right channel and then it was never finished and sat for 10 years. So I thought I would take a chance and see if I could repair it. As I mainly repair tube gear, I haven't really worked on any SS amps with this many transistors in it.
Not sure if anyone is familiar with this unit, it has a massive power transformer and caps creating -50, +50 for the power transistors and also feeding back to the predriver board and also +75, -75 volts also feeding the predriver board. Taking the power module apart is quite a task in these amps. You have to unscrew the predriver module( more on that later) , then there are 4 PC board which are soldered and have to be removed before getting access to the power output transistors. Then you have to unscrew each heatsink for 3 transistors.
Each channel has a pair of NPN feeding 4 PNP(-50) and then 2 PNP feeding 4 NPN (+50). The right far bank had 2 transistors removed (which had been worked on), and in a bag came with a few more NPN predrivers and a blown PNP and some screws.
So what I really should of done was just order all new transistors from Mouser/DigiKey On semi makes them. The part #'s on the original transistors are AR part numbers and here are their equivalents for reference.
300024(NPN) MJ15015
300025(PNP) MJ15016
300027(PNP)MJ15004
300028(NPN)MJ15005
There are total of 24 transistors in the power section of this amp. My mistake was to look for and shorted or out of spec transistors and replaced them. As only having a cheap transistor checker I got them as close as I could matched (hfe) and there were no shorts and more. I then got reading that a lot of issues were caused by the predriver board.
The predriver board consists of 2 sealed AM-1, AM-2 IC type modules which have quite a few transistors in it and cannot be purchased any more. One fellow on another thread(repairing the AR 110 modules) has designed some replacement modules to replace the AM-1, AM-2 units.
I verified that mine were ok and I had signal through both. After fixing the bad transistors I fired the unit up slowly on a variac and no shorts or smoke and voltages were ok.
I had gain in both channels . The left seemed a bit bit lower but with a 1kHz signal across a 100 watt 8ohm load , I scoped the outputs and sine wave looked good, but I had some neg DC offset, meaning some DC was leaking onto the speaker terminals. In some amps there are gain and DC offset controls to adjust this, but in these amps there are none.
Reading more, the DC offset in the output is most likely caused by mismatched transistors, or in reading the other post some of those AM-1. AM-2 modules could cause the neg offset.
I went over the output section again replacing a few more transistors and then somehow turning it back on I was getting the full -50v on the output. It looked like a short somewhere.
Well pulling my hair out I decided to replace all the outputs and now I have less than 20mv on each channel. One or more of the original transistors must of have been bad and not picked up by the tester until full DC power was applied to the output.
I have attached the schematics. I am now in the process of working on the predriver board with the new boards that another member designed.
I will continue this later, hopefully this helps someone else.You can get bigger versions of these schematics from the AR site.
Attachments
Preamp with #46, 47, and 49
- By andyjevans
- Tubes / Valves
- 12 Replies
Interested in seeing who is using any of these three tubes for a line stage, preamp or driver stage. Ale Moglia is a fan of both 46 and 47, see here...
https://www.bartola.co.uk/valves/?s=46
https://www.bartola.co.uk/valves/2020/07/25/300b-se-amp-47-driver/
I have also used 46 and 47, but not 49. The 46 is better sounding to me, but has a mu of 5.6 whereas 47 is 8. Same filament supply. Ale has used filament bias on these tubes despite the big heatsink and cathode resistors required, but gave up on it. I'm persevering with filament bias - it's always my choice where possible.
Here's a driver stage for my 2a3 outputs, with a 1:4 SUT for added gain. I also use a 10Y driver stage for the 2a3 but they're getting very expensive so I need an alternative as a daily driver. Big heatsink required for Rod's regs, and something like 100W metal clad cathode resistors.
https://www.bartola.co.uk/valves/?s=46
https://www.bartola.co.uk/valves/2020/07/25/300b-se-amp-47-driver/
I have also used 46 and 47, but not 49. The 46 is better sounding to me, but has a mu of 5.6 whereas 47 is 8. Same filament supply. Ale has used filament bias on these tubes despite the big heatsink and cathode resistors required, but gave up on it. I'm persevering with filament bias - it's always my choice where possible.
Here's a driver stage for my 2a3 outputs, with a 1:4 SUT for added gain. I also use a 10Y driver stage for the 2a3 but they're getting very expensive so I need an alternative as a daily driver. Big heatsink required for Rod's regs, and something like 100W metal clad cathode resistors.
WO24TX Magnet Mounting
Siegfried Linkwitz wasn't happy with the how the energy from bass drivers in the Orion OB speakers caused the upper baffle to vibrate. To counter this, in version 3.2, he & his buddy Don Naples came up with a mounting bracket that holds the 8" mid driver by its magnet. The basket doesn't touch the front baffle at all; it only touches a gasket in the hole that the driver appears to be mounted in. The top baffle is still attached to the bass bin, so it doesn't eliminate all bass vibration, but at least reduces the vibrations reaching the tweeter from both the mid 8" and the woofers.
In the LX521, with a less well supported minimal upper baffle, he abandoned this idea. Instead the upper baffle is mounted on a completely separate structure that makes no direct contact with the bass bin. But the 8" low mid driver is mounted on that minimal baffle, and there's no question its energy, with a high pass @ 120Hz, still causes that baffle to vibrate. The "bridge", as SL called it, also looks inelegant and becomes awkward when you try to re-position the speaker -- there are 2 structures to be moved.
In the project for my friend Mark, I wanted to combine the Linkwitz-W-frame of dual-opposed OB bass (used in Orion v 3.3) with the magnet mounting scheme. The bracket would be secured to the heavy top panel (24mm BB + plate of supporting steel or aluminum), and the low-mid driver would not touch the upper baffle. The W-frame's dual-opposed bass drivers dramatically teduces the vibration from the woofers, too.
The chosen low-mid driver is the Satori WO24TX. It will cross at 110~140 Hz (TBD experimentally in situ). Even with a steep LR4 filter, there's still a fair amount of vibration in the driver frame when it's working hard.
The Satori cone drivers all feature a cast aluminum frame with spokes that wrap around the magnet. This is a design that goes back to Peerless, VIFA, ScanSpeak, even JBL.
Here's a Peerless/VIFA NE149 using this design. This is meant to eliminate the "bell-like ringing" of a big heavy magnet that usually hangs off the back of the frame.
The WO24TX (and other WO24 variants) looks similar, like the Peerless driver above and its other Satori mates. But it's an illusion.
The ribbed black portion around the magnet is actually made of molded rubbery plastic & is easily peeled off.
This proved to be a saving grace for the magnet mounting modification that Mark undertook with his talented machinist friend. The rest of the pics should be self explanatory.
The BB plywood frame is temporary and will be replaced in the final version with an aluminum or steel structure with less acoustical resistance.
In the LX521, with a less well supported minimal upper baffle, he abandoned this idea. Instead the upper baffle is mounted on a completely separate structure that makes no direct contact with the bass bin. But the 8" low mid driver is mounted on that minimal baffle, and there's no question its energy, with a high pass @ 120Hz, still causes that baffle to vibrate. The "bridge", as SL called it, also looks inelegant and becomes awkward when you try to re-position the speaker -- there are 2 structures to be moved.
In the project for my friend Mark, I wanted to combine the Linkwitz-W-frame of dual-opposed OB bass (used in Orion v 3.3) with the magnet mounting scheme. The bracket would be secured to the heavy top panel (24mm BB + plate of supporting steel or aluminum), and the low-mid driver would not touch the upper baffle. The W-frame's dual-opposed bass drivers dramatically teduces the vibration from the woofers, too.
The chosen low-mid driver is the Satori WO24TX. It will cross at 110~140 Hz (TBD experimentally in situ). Even with a steep LR4 filter, there's still a fair amount of vibration in the driver frame when it's working hard.
The Satori cone drivers all feature a cast aluminum frame with spokes that wrap around the magnet. This is a design that goes back to Peerless, VIFA, ScanSpeak, even JBL.
Here's a Peerless/VIFA NE149 using this design. This is meant to eliminate the "bell-like ringing" of a big heavy magnet that usually hangs off the back of the frame.
The WO24TX (and other WO24 variants) looks similar, like the Peerless driver above and its other Satori mates. But it's an illusion.
The ribbed black portion around the magnet is actually made of molded rubbery plastic & is easily peeled off.
This proved to be a saving grace for the magnet mounting modification that Mark undertook with his talented machinist friend. The rest of the pics should be self explanatory.
The BB plywood frame is temporary and will be replaced in the final version with an aluminum or steel structure with less acoustical resistance.
History + archeology = treasures (V-FET)
- By StevenOH
- Solid State
- 50 Replies
Here I would like to address the little known events of the early (1973-75) V-FET history.
While it is not very logical to discuss these issues on DIY forum, considering the international
membership and technical expertise, and in the interests of the history preservation I decided
to do it on this forum.
Besides, history + archeology = treasures.
Those years were, in fact, the peak of the industry interest and involvement with the V-FET.
And that all started, as we know, in Japan. The first name we should start with is Toshiba.
Creating in 1973 their high-end audio division Aurex they immediately set standards
very high with the very advanced tuner ST-910. On the audio front they were busy developing
their V-FET (complementary outputs and drivers), which they had in the beginning of 1974.
By 1975 they have the production prototype amp SB-620, (here is their prototyping circuit):
and then...something strange have happened: the SB-620 was completely redesigned into
all BJT design! As we will see this was progressing like a plague...
Talking about Toshiba components in those years, I would ask: shouldn't there be a control
amplifier SY-910 (to supplement their tuner and power amp SC-910, mentioned on the TVK)?
↴
While it is not very logical to discuss these issues on DIY forum, considering the international
membership and technical expertise, and in the interests of the history preservation I decided
to do it on this forum.
Besides, history + archeology = treasures.
Those years were, in fact, the peak of the industry interest and involvement with the V-FET.
And that all started, as we know, in Japan. The first name we should start with is Toshiba.
Creating in 1973 their high-end audio division Aurex they immediately set standards
very high with the very advanced tuner ST-910. On the audio front they were busy developing
their V-FET (complementary outputs and drivers), which they had in the beginning of 1974.
By 1975 they have the production prototype amp SB-620, (here is their prototyping circuit):
and then...something strange have happened: the SB-620 was completely redesigned into
all BJT design! As we will see this was progressing like a plague...
Talking about Toshiba components in those years, I would ask: shouldn't there be a control
amplifier SY-910 (to supplement their tuner and power amp SC-910, mentioned on the TVK)?
↴
OLD THREAD Hi-end phono preamplifier by Andrea Ciuffoli
- By quanghao
- Quanghao Audio Design
- 459 Replies
