Lockdown project Nostalgia build
OK So maybe I'm just bored but I have almost finished the new shed build and soon I will have a workshop of sorts.
I've had some drivers sitting on the shelf for yonks and it's about time I either used them or chucked them out.
I'm thinking 1970's Japanese Rock&Roll speakers using a little Coral woofer I salvaged 30 years ago as the midrange.
It was labeled 10watts input when I grabbed it off the street in a pile of stuff. Box was rotten and no other parts salvageable
It got very hot using it in something else so I glued a heat sink to the magnet back, scrapped that experiment but kept the driver.
I have a pair of 15" woofers from a Jaycar party box and a selection of old cone tweeters and cheap dome midranges
Input asked for but somewhere in the stash would be a pair of old Tandy 3-Way crossovers that might suit this sort of cobbled together junk or I could find enough bits to assemble a near enough good enough project. Then use it in the shed until it blows up
I've had some drivers sitting on the shelf for yonks and it's about time I either used them or chucked them out.
I'm thinking 1970's Japanese Rock&Roll speakers using a little Coral woofer I salvaged 30 years ago as the midrange.
It was labeled 10watts input when I grabbed it off the street in a pile of stuff. Box was rotten and no other parts salvageable
It got very hot using it in something else so I glued a heat sink to the magnet back, scrapped that experiment but kept the driver.
I have a pair of 15" woofers from a Jaycar party box and a selection of old cone tweeters and cheap dome midranges
Input asked for but somewhere in the stash would be a pair of old Tandy 3-Way crossovers that might suit this sort of cobbled together junk or I could find enough bits to assemble a near enough good enough project. Then use it in the shed until it blows up
Attachments
Need XPS foam help
Hi all, to any working with XPS foam...
I'm in process of making some secondary flares for a synergy project out of Lowes XPS foamboard.
All web searching leaves me confused how to best harden and strengthen it.
Ideally I'd like something that brushes on thin per coat (less than 1/16th) and is sand-able, and of course paint-able with nothing special.
Many Thanks 🙂
I'm in process of making some secondary flares for a synergy project out of Lowes XPS foamboard.
All web searching leaves me confused how to best harden and strengthen it.
Ideally I'd like something that brushes on thin per coat (less than 1/16th) and is sand-able, and of course paint-able with nothing special.
Many Thanks 🙂
Question about dual (positive-negative) power supply board
- By safe1
- Power Supplies
- 5 Replies
Attachments
Working the crossover for better impedance
- By Kustomize123
- Multi-Way
- 106 Replies
This thread has been split from - What amp should I be looking at for 4 ohm?****
Wow thankyou! Just the answer I was looking for!
My speakers share two 8ohm woofers in parallel.
Zaph|Audio - ZA5 Speaker Designs with ZA14W08 woofer and Vifa DQ25SC16-04 tweeter
I have the 5.3T.
The crossover is there too.
Would someone be able to guide me on how to go on about working the crossover for better impedance?
2x silent switcher power supply
- By pistollero
- Swap Meet
- 1 Replies
For sell 2x silent switcher power supplies.
60 euros both including shipping in europe. Good for dacs, opamps etc.
60 euros both including shipping in europe. Good for dacs, opamps etc.
Push-Pull VAS [50W@8R]
- By BF245C
- Solid State
- 31 Replies
Hello, after a long time, I've finally built a working amp based on the designs discussed on THIS thread.
What I can say right away is: I was impressed with how the circuit showed great stability on a breadboard and with no compensation network, no thermal feedback and exhibited symmetrical clipping and no visible crossover distortion even at insufficient bias.
The circuit (all components used are exactly the same):
Shown below is the early prototype (with much reduced parts count):
Final prototype (25000uF per rail):
Now let's jump to the measurements:
Some extra considerations:
— Sound card used was a Creative Sound Blaster X-fi HD (SB1240);
— You can get more than double the SR by changing the compensation network and the low pass input RC filter, I only chose these values so I could show that the amp is stable with unrealistic capacitive loads;
— I only chose a TL081C as DC servo because I didn't want to use my expensive JFET input op amps (also it'd be a pain to solder because they're all SMD) but I encourage everyone to use something better, the datasheet says it's immune to latch-up but THAT'S A LIE, and a HUGE problem if your finished design doesn't have output DC protection;
— I couldn't realiably measure damping factor at and above 10kHz because my multimeter does not have the bandwidth (I don't think most of the do anyway) and my scope doesn't have the accuracy (I was measuring at full power output) for measuring high voltages with mV precision, but I have strong evidence that the DF doesn't stray far from the 1800:1 across the entire audio spectrum;
— I didn't measure IMD at full power because the generator was the same external sound card that was analyzing the output signal and I had no way to isolate the input to prevent a ground loop (at low power it was fine because no high currents were involved and the grounding layout worked fine). For those interested, it measured 0.045%;
— The heatsink used is working on its limit, I had to set the idle (cold) current very high to achieve the idle (hot) current I wanted. Before I realized this, the insufficient heatsink size made it so that after 30min the idle current had fallen way below what I had set initially. I recommend choosing a bigger heatsink;
— You can extract more power from the circuit by making the driver stage a single BJT emitter follower instead of the discrete Darlington emitter follower I chose, at the cost of higher loading of the VAS;
— The amp was not tested with 4R loads because my transformer can't supply enough current, thought the circuit can probably handle 4R without problems.
Applying capacitive loads:
I will not be supplying the .asc file (unless someone really wants) because I don't have most of the models, I just renamed the components on the schematic above to match what I used in real life.
What I can say right away is: I was impressed with how the circuit showed great stability on a breadboard and with no compensation network, no thermal feedback and exhibited symmetrical clipping and no visible crossover distortion even at insufficient bias.
The circuit (all components used are exactly the same):
Shown below is the early prototype (with much reduced parts count):
Final prototype (25000uF per rail):
With only one pair, the THD was limited to 0.005% @1W and 0.030% @50W, adding an extra pair allowed me to have much better THD at full power and also increased the Damping Factor from ~300 to the values shown below.
Now let's jump to the measurements:
- Frequency Response: 4Hz ~ 147kHz
- Noise (Max Vpp): <20mVpp
- Noise (Max Vrms): <4mVrms
- Slew Rate: >30V/us
- Max DC Offset: <3mV
- Damping Factor (50W/8R/20Hz): 1820
- Damping Factor (50W/8R/100Hz): 1870
- Damping Factor (50W/8R/1kHz): 1870
- THD (1W/8R/1kHz): <0.002% (limited by signal gen. THD)
- THD (50W/8R/1kHz): <0.006%
- Phase Shift @20kHz: <10.2°
- IMD (1W/10kHz+11kHz/1:1 ratio): <0.004%
- Input Sensitivity: 360mVrms
- Voltage Gain: 34dB
Some extra considerations:
— Sound card used was a Creative Sound Blaster X-fi HD (SB1240);
— You can get more than double the SR by changing the compensation network and the low pass input RC filter, I only chose these values so I could show that the amp is stable with unrealistic capacitive loads;
— I only chose a TL081C as DC servo because I didn't want to use my expensive JFET input op amps (also it'd be a pain to solder because they're all SMD) but I encourage everyone to use something better, the datasheet says it's immune to latch-up but THAT'S A LIE, and a HUGE problem if your finished design doesn't have output DC protection;
— I couldn't realiably measure damping factor at and above 10kHz because my multimeter does not have the bandwidth (I don't think most of the do anyway) and my scope doesn't have the accuracy (I was measuring at full power output) for measuring high voltages with mV precision, but I have strong evidence that the DF doesn't stray far from the 1800:1 across the entire audio spectrum;
— I didn't measure IMD at full power because the generator was the same external sound card that was analyzing the output signal and I had no way to isolate the input to prevent a ground loop (at low power it was fine because no high currents were involved and the grounding layout worked fine). For those interested, it measured 0.045%;
— The heatsink used is working on its limit, I had to set the idle (cold) current very high to achieve the idle (hot) current I wanted. Before I realized this, the insufficient heatsink size made it so that after 30min the idle current had fallen way below what I had set initially. I recommend choosing a bigger heatsink;
— You can extract more power from the circuit by making the driver stage a single BJT emitter follower instead of the discrete Darlington emitter follower I chose, at the cost of higher loading of the VAS;
— The amp was not tested with 4R loads because my transformer can't supply enough current, thought the circuit can probably handle 4R without problems.
Applying capacitive loads:
- 1nF and lower: no visible change
- 10nF: no visible change
- 100nF: small oscillation over the negative part of the square wave
- 1uF: very large overshoot but stops immediately, doesn't break down into a chaotic oscillation
I will not be supplying the .asc file (unless someone really wants) because I don't have most of the models, I just renamed the components on the schematic above to match what I used in real life.
Attachments
KISS: or the art of the 2.5 way
Just wanted to get back to something simple for my new home. I started with my super lightweight bamboo enclosures filled with my custom FR151's, along with a miniDSP 2x4HD, and it's sure fun, but as an incorrigible DIYer: I wanted another project. 😱
So, using the same 2x4HD, what are the options?
Well, i'm not a big fan of 2-ways... It's either fullrange or 3/4 ways.
But what about a 2.5-way?
A 2.5-way is the poor man's 3-way, which means I use the highpass channels to feed both the mids and tweeters, and I finish the job with some basic passive xovers (6db/oct in my case, cannot be simplier).
I'm not saying it's an easy task to make it work properly nor that the results can compete with an elaborate 4-way system, but it can be excellent for the money/time spent.
So here is my new little 2.5 project:
Tweeter: RAAL 64-10 (ribbon)
Midrange: Visaton B200 (widely used as a fullrange)
Sub/woofer: JL audio 8W1v3 (4 total)
Dayton 12'' passive radiator (tuned @ more or less 33hz)
Very thin on-wall enclosures, made of 10mm bamboo
MiniDSP: 315hz xover @ 48db/oct BW
Tweeter/mid @ 4.5khz @ 6db/oct
Amplifier: ICEpower
Basically, I chose a recipe with what I had on hand. But first I designed the project using (2) TW1 subwoofers and finally added bamboo panels to modify the whole thing to fit (4) 8w1v3, for a better 150-300hz response, which is not the Visaton's forte and even less the TW1's...
After few hours spent on the measures and EQ, I can say: mission accomplished. 🙂
Now, all I need is to finish the job with some protective grill to cover that DIY mess 🙄
So, using the same 2x4HD, what are the options?
Well, i'm not a big fan of 2-ways... It's either fullrange or 3/4 ways.
But what about a 2.5-way?
A 2.5-way is the poor man's 3-way, which means I use the highpass channels to feed both the mids and tweeters, and I finish the job with some basic passive xovers (6db/oct in my case, cannot be simplier).
I'm not saying it's an easy task to make it work properly nor that the results can compete with an elaborate 4-way system, but it can be excellent for the money/time spent.
So here is my new little 2.5 project:
Tweeter: RAAL 64-10 (ribbon)
Midrange: Visaton B200 (widely used as a fullrange)
Sub/woofer: JL audio 8W1v3 (4 total)
Dayton 12'' passive radiator (tuned @ more or less 33hz)
Very thin on-wall enclosures, made of 10mm bamboo
MiniDSP: 315hz xover @ 48db/oct BW
Tweeter/mid @ 4.5khz @ 6db/oct
Amplifier: ICEpower
Basically, I chose a recipe with what I had on hand. But first I designed the project using (2) TW1 subwoofers and finally added bamboo panels to modify the whole thing to fit (4) 8w1v3, for a better 150-300hz response, which is not the Visaton's forte and even less the TW1's...
After few hours spent on the measures and EQ, I can say: mission accomplished. 🙂
Now, all I need is to finish the job with some protective grill to cover that DIY mess 🙄
