Vinyl printers PCB
- By NickKUK
- Construction Tips
- 6 Replies
The Mrs has just bought a Cricut Joy, a small plotter/cutter that can do vinyl. A bit cumbersome to load up a design but I just tried a first print of a svg file. Almost successful..
There’s obviously a few gotchas importing svg files - so anyone else use a vinyl cutter?
There’s obviously a few gotchas importing svg files - so anyone else use a vinyl cutter?
Phono MM preamplifier - Linear Technology
I am selling one Phono MM preamplifier based on Linear Technology schematic.
I've used Very Low Distortion and high-quality opamps LT1028, LT1010 from Linear Techology.
All the component are measured and high quality.
For more details, please send me private message.
The price is 235 Euro + shipping to EU only.
I've used Very Low Distortion and high-quality opamps LT1028, LT1010 from Linear Techology.
All the component are measured and high quality.
For more details, please send me private message.
The price is 235 Euro + shipping to EU only.
The DIY Midrange Dome Teggstreme Driver (or the epoxy calcium carbonate matrix dome)
Calcium carbonate compounds can make very successful structures and are found e.g. in eggshells. The matrix of eggshells is made of 90% calcium carbonate, and eggshells show some remarkable mechanical properties. So, then why calcium carbonate, as to my knowledge, has never been assessed as a material or compound for midrange or high frequency domes?
Textreme is carbon an epoxy. Epoxy is the binder for the otherwise flexible carbon fabric. And carbon acts as a «filler» for the epoxy resin, providing tensile strenght for the cured resin. Think in an analogy now: Instead of flexible carbon fabric, now take an eggshell as a static, calcium carbonate matrix filler for the epoxy resin. Simply think of teggstreme, so to say ...
As eggs include nicely dome-shaped parts, you could easily resort to an egg to assess the question, wheter calcium carbonate is suited fore midrange domes. An egg, as is, might result in an approx. 2-incher, then. So, lets make a midrange dome driver out of an egg, some drops of epoxy and of an outranged midbass driver. We will hopefulle end up with an eggcellent result. And for shure it will be an eggxeptional construction.
Lets go, then:
1. Choose an egg, take a handsaw and start smoothly sawing – if the egg is of decent quality from well-fed chickens, it will not brake. If instead several eggs brake, one after the other, then you may change your egg supplier. You will discover that the surface of a robust enough egg is quite resistant to a usual HSS saw blade, not unlike a ceramic surface, until you have managed to make a first groove. You have to be steady, delicate and patient.
2. Then you will have to take away all (!) skin structures from the inside of the egg shell. You can peel the main skin right away. But then you will have to scratch repetitively and for a quite long time the inside of the shell with your fingernails, until you really scratch on the calcium carbonate structure. Cleaning once and then with water from the tap helps. Let then the eggshell completely dry.
3. Carefully and smoothly sand the cutted edge with a sheet of sanding paper lying on a plane tabletop. 120- or 180-graded paper do well, no coarser, not to split small fragments away. Sand until the rim is more or less on one single plane.
4. As the eggshell is highly porous and fragile at the same time, you may reinforce it by applying epoxy into it. Do not laquer it, but gently work some expoxy into the eggshell by using your gloved (!) fingertips. Then wipe the spare epoxy away with a Cleenex or so.
5. When the epoxy has cured/hardened, the dome already is much more rubust and has gained some moderate elasticity. You may then apply a second, very thin layer of epoxy, then wait for it to get sticky, and then you may add some carbon rowing filaments.
6. An eggshell alone does not make a midrange. For a first assembly, any standard cone driver can be dismantled. In this case, it was a 6.5-inch Audax HDA driver. With scissors, the membrane may be trimmed down to a residual cone slightly larger than the dome circumference. This residual bit of cone will then act as the dome carrier cone.
7. Glue the dome onto the carrier cone. To insure a neat fit, eventially stuff some carbon rowing, slightly moisted with epoxy, around the rim of the dome, into the groove between the outside of the dome and the carrier cone.
8. The moving assembly will never be dynamically symmetric. The asymmetry might be slight, but may produce substantial tilting forces and maybe even dynamic rub between the voice coil and the walls of the magnetic gap. In this case, you may try to hand-tune this asymmetry by adding a small weight at the right place into the groove formed by the dome and the carrier cone.
On the To-Do-List now are some measurements, which hopefully I will be able to perform in some days.
Apart from the fun, the immediate reward of this project was … the further processed, main waste of the membrane construction process: It became a delicious fried egg.
Textreme is carbon an epoxy. Epoxy is the binder for the otherwise flexible carbon fabric. And carbon acts as a «filler» for the epoxy resin, providing tensile strenght for the cured resin. Think in an analogy now: Instead of flexible carbon fabric, now take an eggshell as a static, calcium carbonate matrix filler for the epoxy resin. Simply think of teggstreme, so to say ...
As eggs include nicely dome-shaped parts, you could easily resort to an egg to assess the question, wheter calcium carbonate is suited fore midrange domes. An egg, as is, might result in an approx. 2-incher, then. So, lets make a midrange dome driver out of an egg, some drops of epoxy and of an outranged midbass driver. We will hopefulle end up with an eggcellent result. And for shure it will be an eggxeptional construction.
Lets go, then:
1. Choose an egg, take a handsaw and start smoothly sawing – if the egg is of decent quality from well-fed chickens, it will not brake. If instead several eggs brake, one after the other, then you may change your egg supplier. You will discover that the surface of a robust enough egg is quite resistant to a usual HSS saw blade, not unlike a ceramic surface, until you have managed to make a first groove. You have to be steady, delicate and patient.
2. Then you will have to take away all (!) skin structures from the inside of the egg shell. You can peel the main skin right away. But then you will have to scratch repetitively and for a quite long time the inside of the shell with your fingernails, until you really scratch on the calcium carbonate structure. Cleaning once and then with water from the tap helps. Let then the eggshell completely dry.
3. Carefully and smoothly sand the cutted edge with a sheet of sanding paper lying on a plane tabletop. 120- or 180-graded paper do well, no coarser, not to split small fragments away. Sand until the rim is more or less on one single plane.
4. As the eggshell is highly porous and fragile at the same time, you may reinforce it by applying epoxy into it. Do not laquer it, but gently work some expoxy into the eggshell by using your gloved (!) fingertips. Then wipe the spare epoxy away with a Cleenex or so.
5. When the epoxy has cured/hardened, the dome already is much more rubust and has gained some moderate elasticity. You may then apply a second, very thin layer of epoxy, then wait for it to get sticky, and then you may add some carbon rowing filaments.
6. An eggshell alone does not make a midrange. For a first assembly, any standard cone driver can be dismantled. In this case, it was a 6.5-inch Audax HDA driver. With scissors, the membrane may be trimmed down to a residual cone slightly larger than the dome circumference. This residual bit of cone will then act as the dome carrier cone.
7. Glue the dome onto the carrier cone. To insure a neat fit, eventially stuff some carbon rowing, slightly moisted with epoxy, around the rim of the dome, into the groove between the outside of the dome and the carrier cone.
8. The moving assembly will never be dynamically symmetric. The asymmetry might be slight, but may produce substantial tilting forces and maybe even dynamic rub between the voice coil and the walls of the magnetic gap. In this case, you may try to hand-tune this asymmetry by adding a small weight at the right place into the groove formed by the dome and the carrier cone.
On the To-Do-List now are some measurements, which hopefully I will be able to perform in some days.
Apart from the fun, the immediate reward of this project was … the further processed, main waste of the membrane construction process: It became a delicious fried egg.
Denon POA6600 under restoration
- By STodorov
- Solid State
- 2 Replies
Good evening to all,
Obviously, this is my first post on this forum, and although I have been looking at the threads for a long time, please excuse me if I am unclear or incomplete. Thanks to many of you, I learned a lot about the DIY audio.
The story is as follows..
I clone/restore amplifier by the attached schematic. The original PCB is in very bad condition and is not repairable, so I decided to clone the board as close as possible to the original.
Once all the elements were soldered in place, I started to check the amp. DC offset is about 4mV.
However, the amplifier oscillates at 1.4MHz, 1V RMS near to pure sine. The volume control is fully turned left, no load at the output. The idle current is affected by the oscillation. The oscillation is also present at the output of the VAS (L501 II R533).
I cut the link between L501, R533 and the next stage. That stops the oscillation at the output and the adjustment of the idle current become possible. No oscillation at the output of the VAS either.
I reconnect the link and check with 1kHz at the input to see the reaction. I started from 10mV to 1V. The clipping point is about 1.1V. On the low levels the 1kHz is affected by the oscillation. Rising the amplitude suppresses the oscillation and at 0.5-0.6V it disappears.
I noticed that the oscillation was affected when I tapped the body of the C523 or C524 with tweezers. The level is halved and sometimes completely disappears. The oscillation is also affected by the Volume potentiometer. In the fully left and fully right position it is about 1V, but when it is in the middle the level drops to 0.5V.
Very strange behavior. Any idea or advice on what to focus on to solve the problem? It will be the worst if it turns out that the reason is in the design of the board ...
Many thanks in advance!
Obviously, this is my first post on this forum, and although I have been looking at the threads for a long time, please excuse me if I am unclear or incomplete. Thanks to many of you, I learned a lot about the DIY audio.
The story is as follows..
I clone/restore amplifier by the attached schematic. The original PCB is in very bad condition and is not repairable, so I decided to clone the board as close as possible to the original.
Once all the elements were soldered in place, I started to check the amp. DC offset is about 4mV.
However, the amplifier oscillates at 1.4MHz, 1V RMS near to pure sine. The volume control is fully turned left, no load at the output. The idle current is affected by the oscillation. The oscillation is also present at the output of the VAS (L501 II R533).
I cut the link between L501, R533 and the next stage. That stops the oscillation at the output and the adjustment of the idle current become possible. No oscillation at the output of the VAS either.
I reconnect the link and check with 1kHz at the input to see the reaction. I started from 10mV to 1V. The clipping point is about 1.1V. On the low levels the 1kHz is affected by the oscillation. Rising the amplitude suppresses the oscillation and at 0.5-0.6V it disappears.
I noticed that the oscillation was affected when I tapped the body of the C523 or C524 with tweezers. The level is halved and sometimes completely disappears. The oscillation is also affected by the Volume potentiometer. In the fully left and fully right position it is about 1V, but when it is in the middle the level drops to 0.5V.
Very strange behavior. Any idea or advice on what to focus on to solve the problem? It will be the worst if it turns out that the reason is in the design of the board ...
Many thanks in advance!
Attachments
Feedback and distortion in Single Ended amplifiers
- Tubes / Valves
- 49 Replies
Hi everyone,
My name is Mark and I have been an audio enthusiast (not quite an audiophile) for over 30 years. Starting out on a very low budget and since then both acquiring and building better and more advanced audio equipment. Although my hearing between 11 kHz and 15 kHz faded over the past 20 years, my fancy for Single Ended amps never did. I just happen to be an engineer also.
Having built a 300B amp some 20 years ago, I now decided to create my own and (at least partly) original design. I didn't want to simply copy on of the 100 designs that can be found on-line, and that have been going around for 100 years. I now finished the design and documented it (see attached).
This design distinguishes itself in the fact that;
I will argue that feedback is a bad thing in a Single Ended amplifier, in case you place your output stage within the feedback loop, which is what (almost) every 300B amp schematic with feedback that I've seen is doing. I do believe it can be an interesting read for those that aren't more knowledgeable than me ;-) If you are, than please catch my errors.
*********
UPDATE
*********
The amplifier has now been built I have been listening to it (with and without NFB to compare) for a couple of days. The final schematic has been attached to this thread.
IT SOUNDS AMAZING. I have written my listening impressions in document 300B_R06 attached for those interested. It's the last few chapters. I'm guessing at this point that 300B tubes are MUCH harder to drive than people think, but if you take control (very low Z-out of the driver) of what happens at the grid of a 300B, the payoff is amazing.
Kind regards,
Mark
My name is Mark and I have been an audio enthusiast (not quite an audiophile) for over 30 years. Starting out on a very low budget and since then both acquiring and building better and more advanced audio equipment. Although my hearing between 11 kHz and 15 kHz faded over the past 20 years, my fancy for Single Ended amps never did. I just happen to be an engineer also.
Having built a 300B amp some 20 years ago, I now decided to create my own and (at least partly) original design. I didn't want to simply copy on of the 100 designs that can be found on-line, and that have been going around for 100 years. I now finished the design and documented it (see attached).
This design distinguishes itself in the fact that;
- Every aspect of the design is documented including background theory, calculations and rationale
- It uses my own 300B self-bias circuit design (using DN2540 that is now in supply again at Reichelt.com)
- It uses my own driver stage design using Negative Feedback (yes, feedback... and with good reason)
*********
UPDATE
*********
The amplifier has now been built I have been listening to it (with and without NFB to compare) for a couple of days. The final schematic has been attached to this thread.
IT SOUNDS AMAZING. I have written my listening impressions in document 300B_R06 attached for those interested. It's the last few chapters. I'm guessing at this point that 300B tubes are MUCH harder to drive than people think, but if you take control (very low Z-out of the driver) of what happens at the grid of a 300B, the payoff is amazing.
Kind regards,
Mark
Building speakers into Entertainment Center
- Multi-Way
- 7 Replies
Forgive me if this is the wrong forum for this question, but I'm about to build my second set of speakers and could use a bit of advice. I built a set of pensils a few years ago, but for this new build I want to build a custom entertainment center and build the speakers into the actual cabinetry. I know I could simply buy a set of in-wall speakers for this use case, and mount them into the cabinets, but since my entertainment center is going to be 16" deep, it seems like I could get better results by custom building something to take advantage of that depth instead of using in-wall speakers that were designed to be installed in 4" thick walls.
Anyway, here's a sketch of what I have in mind. I plan on doing a 3.1 set up. This is our main TV in our family room area, so I feel like I need a center channel for the TV, but the stereo performance is just as important to me. My question is, can anyone recommend a kit that would function well if built into an entertainment center? I can make the speaker "compartments" any size I want, but in this sketch I have them at 16x18x16", so I was thinking something similar to the Seas A26 kit from Madisound might do the trick?
Anyway, here's a sketch of what I have in mind. I plan on doing a 3.1 set up. This is our main TV in our family room area, so I feel like I need a center channel for the TV, but the stereo performance is just as important to me. My question is, can anyone recommend a kit that would function well if built into an entertainment center? I can make the speaker "compartments" any size I want, but in this sketch I have them at 16x18x16", so I was thinking something similar to the Seas A26 kit from Madisound might do the trick?
Dashboard cover speakers of a 97 Brazilian VW.
I own this 1997 VW Quantum, which is a version of the VW Passat SW and it has a pair of speaker on the left, driver's side, and another pair on the passenger side. The configuration is mid-range + treble on the door and bass just over the dashboard cover. Considering it has a 4 cylinder 1.8L gasoline engine, it seems to me, the idea was to place all the bass over the cover to mask the engine roar, am I right? If so, it must have a low-pass before the dashboard cover and a high-pass just before the door speaker. In this case, what should be the cutt-off frequency of the filters, because I think the cross-over filter is not deafult as I bought it second-hand, maybe third or fourth-hand. Picture 1 and 2 are random while the others are the actual car.
Looking for thoughts on cosmetics of upcoming EICO HF-87 Restoration
- By Cycline3
- Tubes / Valves
- 8 Replies
Attachments
For Sale Unused Plitron 3kVA Encapsulated Toroidal Medical Transformer
Another Plitron toroid from my "future projects" stash. Quite heavy (40lbs, 18kg), so local pickup in Carlsbad CA would save on shipping this beastie. Asking $250 + shipping.
Cheers, -Casey
Cheers, -Casey
FS: Large Power Supply Capacitors; 25,000uF, 250VDC
Preparing to downsize. I have a large number of 25,000uF, 250VDC capacitors for use in big power supplies. They were all re-formed many years ago when I had my shop. These were destined for use in a mega-amplifier I had planned to build. Some of you DIY old-timers might recognize the rather ambitious project from the pictures.
These are a mix from Phillips, Sprague, United Chemi-Con, and possibly others. They are 3" in diameter and about 9" tall. They will ship from Encinitas, California. Asking $15 each, plus shipping. Local pick-up is also fine. I can investigate shipping costs for anyone with real interest. I can negotiate price if you are interesten in quantities.
Thumbnails might be distorted. Click on images for proper resolution.
Cheers,
-Casey
These are a mix from Phillips, Sprague, United Chemi-Con, and possibly others. They are 3" in diameter and about 9" tall. They will ship from Encinitas, California. Asking $15 each, plus shipping. Local pick-up is also fine. I can investigate shipping costs for anyone with real interest. I can negotiate price if you are interesten in quantities.
Thumbnails might be distorted. Click on images for proper resolution.
Cheers,
-Casey
Attachments
Boozehound Laboratories JFET Buffer Full Kit NIB
- Swap Meet
- 1 Replies
SOLD SOLD SOLD SOLD SOLD SOLD
Boozehound Labs JFET Buffer Full kit: Pc Board and components. MSRP $99. Asking $50 with shipping included to lower 48 only, please.
Boozehound Labs JFET Buffer Full kit: Pc Board and components. MSRP $99. Asking $50 with shipping included to lower 48 only, please.
Alpair 7 Gen 3
For sale 2 sets (of two) Alpair 7 Gen 3 speakers. I am the original purchaser. Never used.
$80.00 for a set of 2. $150 for both sets (4 speakers total) if sold to same purchaser. Free shipping. Double boxed. Paypal.
Thanks.
$80.00 for a set of 2. $150 for both sets (4 speakers total) if sold to same purchaser. Free shipping. Double boxed. Paypal.
Thanks.
Elements between PCB-GND and Mains Earth in SolidState Power Amps - How to Calculate?
- Solid State
- 40 Replies
Attachments
Chas F3 clone boards
Decided this is an amp that may not be for me, so I offer the complete set of boards here.
All came direct from Chas, the 2 amplifier boards are from his early batch and so are not ENIG, but the rest are from his production run and so are ENIG.
Looking to get back what I paid so they are £40
Thanks
All came direct from Chas, the 2 amplifier boards are from his early batch and so are not ENIG, but the rest are from his production run and so are ENIG.
Looking to get back what I paid so they are £40
Thanks
Advice to Prevent Seizing
- By WntrMute2
- Construction Tips
- 16 Replies
Somewhat basic question. I have some tube pin cooler connectors that keep seizing the internal threads. I believe they are aluminum and the screws seem to chrome(ish) plated brass. After a month or so of running for a few hours per day, the screws are impossible to remove without snapping the heads off rendering them useless. Interestingly, the steel set screws that clamp the parts on to the tube pins seem to not be effected. Usually, I can back the screws in question out about 1/2 a turn before the problem sets in. I could try some aluminum screws and I have some anti-seize compound I could try but any other ideas?
The connectors in question are expensive and hard to source.
The connectors in question are expensive and hard to source.
