I am used to Voltage Feedback design but wants to get into Current Feedback Design but their some problem.



Most CFA example i can find a diamond buffer based ,which are known to cancel 2nd order distortion , which are the last thing i want.

I want to start this thread so that i can get introduced to some CFA input state design. 🙂

Typical center channel speakers have never really worked for me. Typical flat screen TVs force you to place the speaker above or below and then you try to angle the CC speaker so you are not always listening off axis. Then there are BR ports that exit the backside making it hard to place them in a TV stand or against a wall. A lot of them (my Paradigm CC370-v4 included) are 2way MTM designs that create off axis horizontal lobes because they XO to the tweeter at high freq.

I'd like to design a CC that is better suited to how I will use it and still work with the rest of my HT system. The room is being renovated, and the CC has to suite the new location (a fireplace column) as best as it can.

The fireplace column will hold a direct vent gas fireplace (Valor Linear + Heatshift kit convection cooling), a 48"x36"x8" pocket for a VESA mounted 50" TV and a center channel speaker. The pocket includes ~5" air space behind the TV (when flush) for convection cooling.

Versions :
V1 : 2x DC130B-4 + CX120-8 Coax : V1 : 2x DC130B-4 + CX120-8 Coax
V2 : 2x DC130B-4, PT6816 Planar : V2 : 2x DC130B-4 + PT6816 Planar
V3 : 4x Dayton PC105-8 : V3 : 4xPC105-8
V4 : 4x DC130b-4, PT6816 Planar : V4 : 4xDC130B-4 + PT6816 Planar
V5 : 4x DC130B-4 + 3FE25-8 + TD20F : V5 : 2xDC130B-4 + 3FE25-8 + TD20F

.

I've bought a load of these and they are genuine.

2SJ74 Toshiba J-FET Transistors QTY 20 - 2SJ74GR - NEW UNUSED - Audio Low Noise | eBay

Hello!
I see people talk about the Onken for EMS B15EX, is the Ciufolli Onken design suitable for this field coil drive unit??


Hi-End and Hi-Eff loudspeakers system

Hi-End and Hi-Eff loudspeakers system 2

Thanks!

Does anyone know somewhere that has stock of genuine JRC5534DD?

Mouser and Digikey etc are showing them as 'no longer manufactured'.

I should add that I'm not interested in 5534's produced by TI, On-semi, Philips or Signetics.

Thanks

I'm refurbishing an old NAD amp and am wondering if I should replace the ceramic disk caps along with the others. Do they age? Does it make sense to replace them with a different type of cap?
Thanks 🙂

I have a commercial phono pre which one is suitable for MM and MC. I don't use MC and never will. In the first stage there is an OP37G used. For my own reasons i want to use a 5534. I am a fan of these with MM and have different brands.

But can i drop in the 5534 with no problems for the op37? In the rest of the cirquit one opamp is used for Riaa and one for IV with pot resistor for offset.

And if so, can i get away with no compensaton cap? What will be the gain of this stage, the 5534 is stable until 3x with no external cap.

I have read about how a ground plane is not a perfect ground and i should connect output gnd to a quiet gnd point then i have a question:
Assume that the rectangular is a solid ground plane. If a current of 1A must flow from gnd load (point B) back to gnd source (point A) and assume that the resistance between A and B is 1R, then a voltage of 1V is developed between A and B. But then what is the voltage different between C (an arbitrary node in ground plane) and A or B? If we measure between A and B we will get 1V but between A and C there is resistance but no current flow so voltage difference between A and C, also B and C will be 0V different, isn't that mean between A and B there will be 0V different?

Hi all. I'm taking inventory of what's in my storeroom after 10 years of tireless R&D, and selling it here in the DIY community because this is where it belongs. Long live we who build!

I'll be posting front-end equipment and amps as well, that's next. All the miniDSP's from my previous post have sold.

Please email me, instead of messaging me here. I love DIYaudio but the in-site messaging system here is from the Jurassic period, it seems. 🙂

db@aforara.com

Many of these woofers are backordered / hard to find. They're all in either new or like-new condition.

Pricing begins at 15% off retail (and no taxes). So multiply the below prices by 0.85 to determine my price.

I'll ship 'em. I'll continue to discount whichever ones don't sell.

• B&C / 21SW152-8 / Qty: 4 / Retail: $780/ea
• BMS / 18N862-8 / Qty: 2 / Retail: $580/ea
• Eminence / Omega-Pro15A / Qty: 2 / Retal: $210
• Fi Car audio / IB318v2 / Qty: 4 / Retail: $275
• Tone Tubby / DD 12" Hemp / Qty: 2 / Retail: $225
• Eminence / Alpha 15A / Qty: 12 / Retail: $80
• 18sound / 15NLW9500 / Qty: 2 / Retail: $400
• SB Acoustic / SW26DBAC76-3-DV / Many! / $190

Reminder: email please, not an private msg. 🙂
db@aforara.com

While listening to the test cabinets of the Alnico CA-80's, I was simultaneously building the DUAL-208's.
Once they were finished I was very disappointed with the lower frequencies.
But in general very nice speakers for my 2nd set.

Hey Perry,

I have a Rockford Fosgate 240x4 that will not power up. I have checked all the outputs and powersupply fets are good. Amp seemed in decent shape. However, the U1610 and U1620R had burn marks and were missing the 2.7ohm resistors. I have applied power to the remote connection and connected the ground and only have about 0.412 vdc on the powersupply center legs.

Hi all,

I designed some weeks ago a small tool to improve my noise instrumentation setup.
In fact, when doing wide-band noise measurement (well beyond what we can simply do with a sound card),
is is more difficult to measure low noise level.
One way is to use RMS measurement with an oscilloscope, but scope sensitivity doesn't go much less than a mV...
My latest AAPSU01 low noise PSU design is an example that can achieve low wide-band noise,
and so building this small tool has been motivate first by that.

So in practical manner, it's a small shielded box that include a low noise, high bandwidth and high gain amplifier.

The design specs are :

• 20Hz to 20MHz measurement bandwidth (-3 dB)
• 4th order Butterworth low pass filtering.
• Individual +20 dB(x10) and +40 dB(x100) outputs BNC
• 12 Vdc@50mA input supply.
• Max input amplitude about 100mVpp (with 12V supply)
• Output noise floor RTI ~ 12µVrms (Equal to En= 2.7nV/VHz)
• Can handle +/- 20VDC input offset voltage (AC coupled)
• Zin= 50 Ohms, AC or DC coupled (internal jumpers)
• Fully shielded design.
• Low cost design (full bom <30€ + PCB)

The design is based on LT6200-10 OPAMP from LinearTech (now AD).
It's a very high speed amplifier with 1.6GHz of GBW product
and less than 1nV/VHz of spectral noise density.


The full schematics is here : WBLNA_schematics


You can show below some picture of my unit and some measurements results.

PCB Kicad 3D view :




Picture of the finished prototype :




100ns pulse test input/output result :




So, i have published this projects as open source and it is available
to download on the GitHub repository here : \OnEAudioProjects\WBLNA
The project has been designed with Kicad 5.0.2

All original design files are available :

• Schematics
• Bill of material (with Mouser order codes)
• Mechanical drawing
• LTspice design files
• Gerbers files
• Panels stickers print

and more...

So i hope that will interest some people. 🙂

(Note that i have few bare PCB's available(4) , anyone interested can get one
with the panel stickers for 6€ worldwide shipping included )

Regards.


Frex

Hi. I'm with this CDP-701ES. It has a lot of fails and bad attempts of repair. A long history. Now it works, and I hope this cd player can help me to repair and adjust OPH-31, 32, and etc... laser pickups.

Well, the problem. There is a Low Pass filter with a OP-AMP that makes a pop-pops sound. I've opened and cleaned of rubber, but there is a hard resint that is very hard to remove.
I've proved acetone, paint disolvent, nitro disolvent, alcohol, gasoline, air hot(with care), and nothing.
So, what can disolver this resin?

Best regards



Shared album - José Manuel Morales Hernández - Google Photos

Shared album - José Manuel Morales Hernández - Google Photos

Help me choose a Mid!

UPDATE AT PAGE 11
3way Studio Design


Hi all!!!

I am designing a system for Studio/Mastering duties and I am doubting about what mid-woofer / Midrange to use. I am looking for the most transparent & flat response among the drivers listed below.

A Mid-Woofer/Mid that can reach up to 3Khz as flat as possible, as my goal is to cross the tweeter around 3500hz.

I still have to choose what configuration to use MTM or a Classic 3way design...

I have in my hands:
x2 Eton Orchestra 11-612/C8/50 RP Woofers (91db sens) Fc around 380Hz
x2 Focal TC90TD5 Tweeters (91.5db sens) Fc around 3000/3500Hz


Options

For MTM

- Eton Orchestra 5-612 (88db sens)
- Scanspeak Classic P17WJ00 6.5" Woofer 8Ohms (88db sens)
- Scanspeak Discovery 15W/8434G00 Midwoofer (87db sens)

Is it true that I get +6db sens when summing two drivers? I actually measured this with two other drivers I have at home, in cabinet, and when summing a 2nd woofer, signal at 1 meter measures around +6db. But I have seen people here that swears its just 3db? I am confused about that...


For 3Way Classic

- Scanspeak Revelator 18M/4631T 7" Midrange (92dB Sens)
- Scanspeak Discovery D7608/920010 MidDome (92db sens) (used by PMC)
- Satori MW19P-4 7.5 Mid Woofer (91.5db sens)


Till know, I am leaning to an MTM design. Although I am also tempted with the idea of using the SS Mid Dome, but I don´t know if it can perform well at mid low frequencies. PMC says it´s cutted at 380Hz? But Fs is 300? pretty close :/

I would really appreciate some input.


Thank you all!

Does anyone run a 99.999% pure Silver Litz Cable to their 310A or 6C6 grid cap?
i.e. Glasshouse Interconnect HGC

If so, have you noticed any improvements or interference with only cotton sleeving?
Are you using .5mm or 1mm diameter?

Hello everyone . Is my first post here so... have mercy 🙂
I play with amplifiers and good music for too many years , i can't remember . The problems start now with all "digital era" .
Well... i can't say is bad thing but i just think will take some time to get back the real analog sound or i need some modif' in my system.
My setups aren't very complicated , Denon AVR2105 for movies stream from my TV and control everything in my home, for music Wangine WFA-220 , Denon POA2200 + preamp PRA1500 , all my speakers are Canton and sub Behringer .
All fit perfect when i listen music, analog source through AVR as controll (i don't use internal power of that amplif) or even optical/coax.
All sound amazing , but when i want to stream in my TV and "passthrough" audio on optical output going in AVR , everything change . The music sound crappy asf. Is like a joke to be honest comparative with any decent CD sources.
I try RF-line in Passthrough PCM option on my TV and i think is just a cover and post processing .
Still what i don't understand is , the movies sound pass DD or DTS with normal quality.
What i missing here ? I'm realy confused.
What i can do ? All i want is to stream music from tidal or spotify from my phone to DLNA and to get at least decent sound.
I was thinking to made or buy a HDMI sound extractor and convert to PCM , like that i can use internal AVR DAC's through optical input.
Sry for my english & Thanks
Bobby

SOLD

6 tubes, 2 briefly used
4 sockets, also 2 used

30 euros for all or send me a PM

Location The Netherlands

I saw a thread on here about Cinder Block Speakers and am very intrigued.

The block I am thinking about using

I'm fairly new to this and could use some help
Here is what I have mocked up so far



Couple Questions and Facts

The ~sealed volume of each cavity is .217 ft cubed. Should I go for a sealed enclosure or a ported. Based on my research a sealed enclosure is both easier and more forgiving. Looking at the gif they have clearly made an effort to combine both cavities which seems like the best course of action for either sealed or ported

Based on the size of the cavities, I think it makes sense to have a 4" driver. The Dayton Audio one I have looked at have a sealed vol of .18ft cubed which means (if i understand) that this cavity is actually WAY too big for those drivers? It would be even more mismatched if you added both cavities to the sealed volume. Any suggested drivers.

Crossovers: I have tried to understand the ideal crossover point but I really am missing something here and could use some advice. I need a crossover for each driver right? This is the tweeter I think makes the most sense Frequency response is 1,600 to 20,000Hz so does that mean I want to get a crossover between 1500 or 2000hz



For additional parts that I need:
Speaker Terminal
Already have speaker cable (14 gauge monoprice)
Gasketing Tape to make seals
Glue to connect wood to cement when complete.
Am I missing anything here?

Any help would be much appreciated. I have tried to do a lot of my own research but i'm very new and don't know what I don't know

Hi all,

While doing interviews and posting at diyaudio I've been secretly working on my own printed audio publication! 😉
I'm happy to report that Linear Audio Volume 0 is at the printer's and you can check out the contents and read article abstracts at Linear Audio | your tech audio resource .
The author line-up will sound familiar here and includes well-known diyaudio members like Joachim Gerhard, Stuart Yaniger, Nelson Pass, Douglas Self, Bob Cordell and others.
Let me know what you think of it!

jd

[ New thread split from here - tube preamp makes rushing noise at speakers]

Hey guys,
So the muting relay works great and the amp sounds good.
There's no hum or noise now.


So now to sort out the headphone amp. Perhaps someone has some suggestions. Right now there's a pretty loud hum in the headphones and the amp sounds distorted. Here's the schematic. The hum may be due to layout. The circuit board and input wires for the headphone amp are close to the transformer. I'm going to change the input wire to shielded cable. Hopefully that works.

Hello everyone,

I ordered two PCB's from Aliexpress some time ago for an active crossover project where i just needed a decent bass amplifier.



The design looked reasonable and at a price of like 2 bucks each they fit the bill 🙂



So i just finished retracing the board and it looks like a simplified version of the leach amp.




The transistors used are a little too expensive for my project, thinking about replacing the input transistors with a pair of 2SA1015/2SC1815, 1145/2705 to 2SB647/2SD667 and drivers and output transistors to BD911/912.

Any thoughts or idea's are welcome.

hi,




I have a denon DP29f turntable. are there any improvements possible in this kind. currently i get fairly loud sound such that my computer 2.0 channel speakers cant be pushed beyond half volume. else the sound distorts. whats really going on? the sound separation is good though and the detail i voice has improved after a adjusted the azimuth a little by hearing tests. this TT sadly has no other adjustments that i can make.. right?

would happy if anyone can give me a few tips o this TT and setting it up correctly.. I am new to using a TT.


thanks!

Amit

Hi
Tomorrow I am going to look at a 1983 Denon PMA 750 Hi Fi amplifier to purchase for my new set up. I'm intending to hook two subwoofers to it which will be powered by my new Crown XLI 800 PA amp

To do this I've already purchased some inline LFE LPF crossovers.

The Denon PMA 750 does not have a subwoofer out RCA on it so the input mismatch I am concerned about seems irrelevant. Crown XLI 800 has RCA inputs and selectable input sensitivity on it 0.775 to 1.4v It is made so it is compatible for home use. The Denon has an input sensitivity of 150mV (pic below)

Does the input sensitivity matter at all as it looks as if there is a mismatch in the specs below (PMA screenshot specs)

Im intending to use this method below as in screenshot, no RCA?



Denon PMA 750 input SPECS



Crown XLI 800

I really like the look of this design. Also the modular nature allowing you to

time align the boxes and also easier to move the speaker around. Just wondering

what the drawbacks to having each driver in a separate enclosure might be. More defraction? Will that show up in the frequency response heavily? Focal

also did this with the Utopia series. Another thing is arent the drivers slightly closer together acoustically this way being that they're all pointed right at the listener?








Here's the design link:

K+T 4-9-9

Hi, I got an nice JVC RC-90M Boombox with an issue with the cassette transport, when I turn it on, all I hear and see is the solenoid momentary going up and down. Nothing else working when I press Play, ff or rewind, the belts are all fine. Not sure if the capstan motor should be spinning all the time on this? I checked on pin 5 of IC701 when i press play it changes from 5V to 0V, so the play switch is working. Pin 18 = 5V as expected. I noticed on the output pin 14 when play is pressed, the voltage stays around 0.7V (no change when pressed or released) I also checked resistance between pin 4 and 8 / 9 and with cassette out it is 1.4kohm and in 7.55kohm so the micro switch that detects the cassette seems ok I think. I checked all the electrolytic caps and all ESR / capacity measure fine. Checked all diodes, and transistors (removed out of circuit) all seem fine. Fr702 =1425ohms, Fr703 = 4.47ohms, fr701= 5.31ohms, (need to confirm these are correct) I also temporarily disconnected pin 11 (power off reset) from the chip, but no change. Could this be a faulty (JVC VUC0002) IC701 chip? Any other suggestions what to check ? I see the photo diode led on. Hoping someone has had the same issue and that there might be a common "known fault" with these transports

Hello again.
A friend brought me a roland acoustic chorus ac-90. Amp is completely dead (no power when flipping the ON switch).
I opened it up (pain in the butt!) and checked power from the cord to the toroidal transformer primary winding. Tomorrow I will continue to search for the fault. It might be something stupid like a loose connector, or it might be more serious, like a blown secondary winding on the transformer. Who knows? I've seen both scenarios before on Marshall and Fender brand amps made in China.
Any suggestions as what else to look for?

Thanks in advance.

I'm in the process of going through an H.H. Scott 348 (not the "B" version"). One amp board is ok, but the other has two bad drivers: Q5 and Q6. Based on the fact that the outputs are both non-original 2N3055s (tested ok), my guess is that one or both of the original Bendix outputs on this side shorted and the person doing the repair never checked the drivers. Or not. . . . Regardless, I'm going to pull the board and check everything.

The failed Q5 and Q6 are what H.H. Scott called "QA-10" transistors. According to a circa 1980 SK catalog I have, this crosses to SK3024/ECG128. If I have to go with NTE128s, I will, but I could use input on a) whether there are any better options, such as the 2N3019, and b) how to address the color-coded grading that Scott used for these, which I assume correlated to hFE and possibly other parameters.

Hi,

I purchased this KT88 based power amp from a HiFi shop back in the late 90's. I had an article on it from a mag but have lost it.

All i know is....its 70wpc, made in Melbourne Australia and the plate is 24k gold.

Anyone have more info on Contan audio in general?

Picture was taken from a b/berry so apologies in advance!

Thanks

In remembrance of course. It's going to be a sombre sequence of events. Serious reflection in the near future likely.

I searched and didn't come up with much more than "it doesn't work". So I did some home work.

LT4320 is called something like an "ideal rectifier bridge controller". But the Figure 2 waveform in the datasheet shows it is a bit less than what you would call "ideal", in that the bottom FETs conduct over most of the input AC voltage cycle, much longer than the duration the top FETs conduct to charge up the output capacitor for.

Apparently such behavior results in the negative node of DC output gets tied to the bottom AC input node most of an AC cycle, and if we were to hook up a center-tapped transformer as well as the split-rail output capacitors, C1, C2, as we usually would to construct a full-wave split-rail PSU, the bottom capacitor C2 would be shorted out by the transformer windings through the bottom FETs during their extra conducting time period (hatched). This appears to be why "it doesn't work".

However, if we could somehow gate the bottom FET drives in such a way that they conduct and cutoff in sync with that of the top FETs', therefore, eliminating the extra conducting time, we probably could make it to work with a center-tapped transformer and be able to make a split-rail PSU with one LT4320.

I came up with a circuit as attached, for a 2 x 24 Vrms input. LTspice simulation indicates it would work just fine.

The 72V maximum voltage rating of LT4320 limits the use of the circuit to up to about +/-35V output. For higher output voltages we are out of luck but have to use two bridges and a transformer with fully separate output winding leads. Nevertheless for preamps and class A power amps that most likely operate under +/-35V, and especiall when having a center-tapped transformer flying around, this circuit perhaps is useful in either saving an expensive LT4320 and the four extra MOSFETs going with it or saving buying a expensive power transformer.

I am short the below parts for finishing some builds and was hoping to buy parts to complete them here on the forum.

12 KSC1845 transistors

8 IRFP140 Mosfets

I am hoping to get these items at normal cost but willing to pay for shipping! The mosfets aren’t as important to get than the transistors.

Any help is appreciated.

I’ve checked how it’s wired up, and it’s earth, live and neutral just like a modern plug. So seems safe.

Just wondering how I can plug it in to try it out.

Dan.

Got a ton of fake 2SK-117 of fleabay, but need a few good real ones!!

Lemme know if you have a few to sell - maybe around 8 - 12?....

Just curious as to the science behind this ... If you were to suspend your main speakers from the ceiling, using a heavy duty bungee cord set up, BUT keeping the speakers the same height off the floor, as if they had standard speaker floor spikes on them. So same height and placement, just not touching the floor by maybe one inch/....
What happens? Should it not help isolate some of the cabinet's vibrations to the floor and wall?

recently purchased new capacitors form one of the big supplies.
i bought 470uf 50v aluminum electrolytic caps.
i tested them to all be around 430uf.
the ones i am replacing are about 30yrs old and test around 460uf.
at 430uf the new ones are still within 20% spec, so do i use them being new and off by 40uf

I'm resurrecting an old Heathkit A8-A amp (see attached schematic) and I have a question about plate current in the two 6L6Gs (which I believe to be original 50s vintage; original spec is 6L6 or 6L6G). It has been completely recapped and all out-of-spec resistors have been replaced.

Plate voltage on the 6L6Gs is 392V; cathode voltage is 26.7V. As measured across the output transformer, the plate current is 53 mA on one tube (8V, 150Ω winding) and 47 mA on the other (7.7V, 165Ω winding). The 10W cathode resistor measures at 254Ω. Measured current across this resistor is 105 mA (26.7V/254Ω), or 52.5 mA per tube.

As I understand it, the recommended bias point for an AB amp is 70% of rated power (I=.7(P/V), or .7(19/392)), which would be ~34mA. If that's correct, the observed measurements seem high.

Questions:
- Do I understand this correctly? Is the plate current higher than optimal?
- Assuming the current is higher than you'd like, what's the best way to lower it? It seems to be a choice between lowering the plate voltage (adding an inline resistor) or bumping the cathode resistor to a higher value.
- If I switch to a pair of 6L6GC tubes (rated at 30W), would that bring things back into spec? If everything else stays the same, that would put the 70% point at 54 mA, which is very close to where it is now.

Answers? Questions? Comments? Insults?

Thanks.

Just looking for some suggestions on which is the better overall dual jfet?

How i can get this amp service manual. Buy or download somewere?

Hello,

I get an amp Genesis Profile 4. However it is not working, I open it and all input caps were dead.
So I have changed them. Next issue is that there are 5 diodes which are also blown. I would like to replace them but I have no service manual and also I can not find any marking on them.
I believe that it is not Zener as no voltage is writen on it or PCB, I have found on PCB place for another diode and on PCB is mark for diode and 12V. So I believe that maker marked Zeners with voltage on PCB.

Based on this I believe that I am loking for standard diode but I do not know which.
Does anyone know it or service manual would be much welcomed 🙂

Thank you

Eminence Crossovers incorperate "aviation light bulbs" for current protection. I like the old-school idea unfortunetly I live in the UK and buying from Eminence is problematic. There must be other sources. In any case they are not magic. How do I know if the bulbs are correct for my speaker?

I'm thinking that pushing 500W through a 4 ohm driver using P= I²R gives me a current of 11.2A and then V=IR gives me a 45V

Armed with that information, how/where can I go shopping?

Hi all, I am new to the forum and, well, I'm here because I made, let's say, a careless mistake. While swapping out the lamps in my JVC SR-201 receiver before having my tea in the morning, I put the wires down for a moment (doh!), and before I knew it, shorted the circuit between the two lamp connectors (pins 911 and 914 on the circuit diagram, square E2). I got some smoke and a burnt out resistor (R805 on the amplification board) and a fuse for my troubles. After replacing the fuse, the amp now will not put any signal out, and it generates a significant amount of heat and smoke if I try to run it even without a load attached, again from that resistor R805, which I've also since replaced. I have tested the transistors on the main board less-than-systematically, and I haven't found any of them to give zero or infinite readings on the ohmmeter.



My question is whether anyone has any useful suggestions from here as to what I might have fried with my carelessness - the service manual is here if it's any help, with the circuit diagram on pp 31-32. I'd appreciate any help, as I am about at the point where I'll just get rid of the thing if I can't fix it.


Thanks for any help you can provide in advance!
FT

As of now I have some simple diy absorption bass traps in my main wall corners. Without doing measurements it seems like it helped tame some of the boomyness? of my small room.

I need to add some more album storage to my little listening den and was wondering about building some bookshelves with 2" of absorption built into the backs to place in each corner in place of the fabric wrapped 2" Rockwool 60 that's up there now.

Basically build a 15ish" deep bookshelf case, with a 13" deep shelf, leaving 2" or so in the back where I can insert my fabric wrapped Rockwool so that it becomes the backing of my bookshelf. These bookshelfs will be mostly filled with albums blocking almost all of the front of the absorption material, but I would leave them and inch or two away from the wall with completely exposed (wrapped in grill cloth) absorption material on the backs.

Is this a terrible idea?

Would it work?

Huge waste of time?

Just build regular bookshelves to put in the corners and don't fool with adding Rockwool to the backs?

Either way the panels are probably coming down and bookshelves replacing them.

So, my 400CX is tripping the rear breaker.

I have replaced a number of PNP and NPN transistors on both output boards as they were testing kaput, plus a bank of .47 and .2 ohm resistors that tested open.

This has made no difference.

The workflow is as follows

Power On - Standby LED illuminates

Button Press - Reg LED illuminates then Bias then click breaker

So all LED illuminate which for debugging is not helpful, I am going to check for when the high signal occurs on the breaker, as this is clearly being sent high (or low I am not sure if it is active LOW or HIGH but I will tell)

It would be good to understand what conditions the MC tells the breaker to trip, there is mV of DC on the terminals even when it trips, so it is not that, I do not know any of the other conditions.

Any help is as always appreciated.

Kiitos

Björn

I'm asking for opinions on whether a four layer PCB will work better than a two layer PCB for audio applications like power amplifiers. A four layer board would have a ground plane.



I've come across varying opinions, without any solid answers.


I'm a retired IC designer beginning to dabble in audio. I've designed switching power supply chips, both buck and boost converters. It was critical that these chips be used with carefully designed four layer boards because of the high frequency currents circulating between the chip and external components. Sloppy design resulted in failure, and two layer PCBs would not work at all.


I have no real experience with designing boards for audio, so any comments will be appreciated.

I'm trying to resolve the issue with DACs connected over USB to the Rapberry Pi 4. I've tested three DACs so far: Alien DAC (based on PCM2702), Topping E30 (based on AK4493) and Khadas DAC (based on ES9038Q2M).

Sometimes when I use VLC for audio playback and when either skip to a different time in the track or switch to a new track the audio drops - no output. That very often happens with Topping and Khadas DACs. That never happens with Alien DAC. Here is the VLC log when that issue occurs:

The last messages repeated over and over again until the playback resumes to normal when I manually switch the audio track.

Probably anybody else faced the same issue and knows how to fix it?
Thanks!

I have a DISPANTE 4U cabinet laying around, with very large heat sinks that I would like to use as an enclosure for a large MOFO Power AMP. It would pump out 20 watts at an idle current of 2.5 amps ( per channel )



The MOFO uses one power transistor / channel that requires a heat sink.
The Dispante 4U uses two equal sized heat sinks per side ( channel ).



Is there a reasonable way to thermally bridge the two heat sinks together, to form one large heat sink?

I have two of these unused and don't see a need for them with my current plans. Would sell for $43 ea. plus shipping/paypal fees.

Please PM with interest.

Thanks
Dan

Good afternoon

I would like mosfet to use the rockford p400x4 in the output since I have none at the moment I just bought it and it would come if they q1, q3, q2, q4, q5, q7, q6, q8 and if the regulator q1002 is equal to q1003 or what goes in its location r27 is missing but must be equal to r26.

I appreciate the information you can provide me

Hello..I have a hifonics txi 1500d broken..Amplifiere was burned and i changed the tl494 , driver transistor,power suply transistor ,and driver hip4080, .Now the power suply work good.the problem is at output transitor because when put the power suply on the amplifier , 3 transistor from photo are very hot,in few seconds are at 100 celsius degrees.
If the voltage remains coupled transistors are destroyed(only 3 pcs).I wil put a photo for see.,.i use irf1310 all output transistor.
I wait the sugestion,what i must to check:|thank you anticipate:|😕😕

Hi:

I am wondering if anyone has experience and success building the ETI-466 300W Amplifier:

http://users.otenet.gr/~athsam/power_amp_300w.htm
or
http://www.alphalink.com.au/~cambie/ETI466Web.htm

I've read a couple of threads on here already and would like to hear from other members who have experience with this design.

I've been working on the module for some time now and after some research on the internet, it appears mine is suffering from high frequency oscillaion in the output/driver stage.

Anybody experience the same problem with this design? Any ideas on how to correct it?

Thanks,

Derek

I'm still a bit unsure if I want to part with these, however I have too much audio equipment and several pairs of speakers hanging around so something needs to go (to maintain matrimonial harmony!).

Looking for £2500

These are phenomenal speakers, constant directivity, true full range (20Hz to 20Hz). I tested them against Wilson Watt Puppies, KEF R3, PMC twenty.25, Troels Gravesen 3WC-15 and these where by far my favourites. You'd have to spend some serious money to equal these if purchasing a traditional commercial speaker.

The only thing you need to be aware of is that these are open baffle speakers - you need to be able to position them out into the room by 1.25m to have the best sound quality. Recommended room size is 25m2 or larger - these speakers are capable of serious volume levels without distortion!

LX521 Description

These have been built exactly to the LX521.3 specification. Original build manual will be provided with the purchase.

Included in this auction:
Pair of LX521 speakers - mdf with oak style veneer. 12 seas drivers installed
(see:
Madisound Speaker Components ... 4-way-kit/)
Sommer Elephant 8 core speaker cables terminated with neutrik plugs - I have a number of pairs, including some 4-5m long. Should be enough for all siting options.
Pair of amplifiers (each amplifier containing three channels of amplification: a stereo LM4780 feeding mid and tweeter, and a single channel Hypex feeding both woofers)
Analogue signal processor (ASP.3) that takes analogue output (XLR or RCA) from your source and splits it to each amplifier channel.

The above is a full active and working system, just add your source/preamp.

Is there any interest in the community to design a RIAA LCR network yourself with the freedom of choosing your favorite impedances, the complete theoretical background, the design calculation and the simulation?
I’m working on a white paper and will publish this article in a couple of weeks in the forum.

Hello there,

i have here a Blaupunkt VR 450, 4-Channel A/B amp.

All 4 Channel have the same problem.

They start really fast with clipping.

I have no idea where to start here.

Looking for one or two X-BOSOZ Preamp PCBs. I don't need but will take the PS PCBs as well if you have the complete set. I have a complete set of all of Mark Johnson PCBs that I had made from the gerber files for the M2X and DIY VFET amp front end cards as well as the Quasimodo V4.

If you have the X-BOSOZ boards to spare, I am sure we can make a deal.

Regards,

Roy

I have a pair of single ended output transformer from electraprint. They are slightly ugly, the laminates have rust on them, and the bells are scratched. They are not too bad, so I would like to know if it is worth doing some “improvement” on them.

1. Can I dismantle the 4 bolts holding the laminates together? I seem to remember reading performance of the air gapped transformers will be affected if they are dismantled, but I don’t remember where and why.

2. These transformers do not have a ground connection. I have come across ground connection from OPT that is basically a wire soldered on the outermost laminate. I would like to know if this is a good practice or no better than grounding the end bell.

3. I am aware that there are heat resistant paint, but I have not been able to find one that is not a spray paint. I wonder how well do regular paint stand up to tube heat, say about 2” from EL84 or 6V6.

4. Is it preferable for the bell side to face the tube heat, as opposed to the laminate side? Or it does not matter enough either way.

Hi!

Does someone have few ( 1 - 4 ) pieces of Tang Band W3-1750SB lying unused? I am working on a speaker project where this sub would be a perfect fit. Sell yours to me!

Offer either with PM or through this thread.

I am located in Finland, Europe,
but I am sure we can arrange delivery (almost) globally.
Thanks for reading.

Best,
Mikko

I am interested in the Pesante or Slimline Chassis to install 5ea NC400 and 5ea SMPS600N400 in. According to the guys at Hypex, I can install these vertically. To do so would require Risers with custom milling to match their mounting points. These are not standardized to match the existing 10x10mm grid.
Another option could be laying them fla: again, custom milling on the baseplat or bottom of chassis itself would be required.



This would be the main element allowing me to use your product instead of any of the other DIY Chassis options out there. I'm hoping that customized risers will be able to be produced and would like to discuss further with you!


Many thanks,
R

I'm in the process of repairing a piece of equipment with ferroresonant transformers supplying some large linear regulators. The transformer hums pretty loudly for a brief instant before the supply shuts off due to undervoltage protections kicking in.

The caps are 20uf at 660vac and 10uf at 660vac. They measure within spec on a handheld meter but that's hardly representative of their in circuit use. I connected them to a regulated high voltage dc supply and watched the current on my 5.5 digit bench meter. The leakage current is unreadable, it looks below the noise floor of my meter. How can that be? They also seem to hold a charge just fine. For reference a small 0.1uf oil cap shows steady leakage in the microamp range which is expected. I just can't believe these old caps have an undetectable amount of leakage. 😕

As the title suggests... Looking to buy the Audiozen DAM control board for my 1121.

Im in the Netherlands, but ill be happy to pay for international shipping if needed.

I'm looking into the possibility of making desktop speakers but I want them to be the best they can be.
Ill be using DSP for any crossovers but I want to use ribbons as far as I can take them.
How low can I go with ribbons for near field?
I'll be sitting only about a foot or two away from the speakers.

Hello good afternoon my friends!

Just stumbled once more over Mr. Ohm.

I find it hard to remember that, for example, the ampere (A) is referred to as I.
Hell, why is that? Just so or is there a sort of a etymology to the denotations?

Hi Everyone,

A while back a bunch of us were able to pick up some excess SOTA 11R drivers. At the time there were no TS specs available but we were told that they were similar to the pluvia 11 drivers. I got tied up finishing up some electronic projects (F4, F3 FE preamp, BA 2018 pre, phidecca dac) so they have been sitting gathering dust on my workshop bench in the meantime. I know that there were some TS parameters posted on fresh, not broken in drivers. What I am interested to hear is :

1.) Are there any broken in TS parameters available ?

2.) What have folks built with them ?

3.) What are the opinions as to their sound quality ?

I do not have the ability to test for the TS parameters myself but I'm looking to do something with my pair. If they truly are like the pluvia 11, the "King of the swingers" box posted by Scott looks appealing, a simple easy build that can get some bass from a full range design. I'd appreciate any feedback.

Thanks,

Paul

I'm thinking of building a subwoofer for home theater use.
I'd like a low f3 (about 25Hz or less) in a small cabinet (about 50 to 60 liters). (but that's probably what everbody wants in a HT sub)

I've done some research and I came across the Augmented Passive Radiator (APR) in Dickason.
An APR is a system with two passive radiators with different size and two chambers. The f3 is half an octave lower than a normal passive radiator with a slightly more volume (20%) of the cabinet.
There's not much info on this forum or the internet about DIY APR's.

Is there anybody out there with some expirience on building an APR?
Or does someone have some more info/examples on DIY APRs?

With Rick Mercer before and during a show. Nice to see them letting their hair down, yes?

RMR: Rick and Jann Arden on Tour - YouTube

Hi all, I have a pretty good collection of 809 tubes that I want to make a class A2 PP amp. Does anyone have a good schematic?

Hi,

I am trying to track down a hum problem with my phono-preamp/poweramp combination. From the surface, it sounds like a "normal' ground/earth loop and most everyone keeps telling me to just figure out where the wrong ground connection is. Based on my experiments I strongly beleive that it is something else. However, I have not found any mention of such a problem before. That may have to do with my lack of expirience. Also, please forgive if I'm getting some terminology wrong as english isn't my first language and most things that I know about electronics I have learned based on German language instruction.


The preamp is based on a kit from puredynamics.com - I'm also in conversations with Georg Ruppert, the designer but we haven't quite figured this one out yet so I wanted to try if I could get some additional insights/ideas here.
The basic design is a JFET/E88CC cascode input followed by cathode follower, RIAA equalization and a second stage based on another E88CC double triode. The second stage uses negative feedback and the overall gain of the preamp can be adjusted by varying the amount of negative feedback. I've wired hat up so that I can switch between 40/50/60 dB of total gain. The fist satge drives about 25 dB of gain. The second stage does 15/25/35 dB based on the amount of negative feedback applied.
Measured output impedance is at 300 Ohms.

The poweramp is a stereo amp using 4x KT88 push-pull. B+ at 390V, 2x 12AX7 for the driver stage.

When the preamp is set to 60dB gain (for MC pickups) a 50 Hz hum can be heard at all but the lowest volume settings on the poweramp. At lower gains it's only slightly audible at very high volume settings.

The devices all use a soft-ground scheme where the amp's common ground is connected to PE/Chassis at a central point through a 10R/5W resistor and a 47pF cap. Opening that connection in one or all devices doesn't change anything.

Disconnecting the turntable does not change anything.

When I measure the hum with an oscilloscope on the preamps output, it goes away when I turn of the poweramp. The hum at the output measures abround 60 mVpp

When I use a cable between preamp and poweramp that has only a single lead for the ground connection, the hum is strongly reduced but not entirely gone. Same effect can be attained by unplugging one of the RCA connections so that the outer/ground contact is not making a connection with the socket.

I can measure the hum even if I don't connect the poweramp at all but only have the cable connected at the preamp side and touch the outer contacts of the RCA plugs so that the ground leads form a closed loop. (The same thing that would be happening inside the power amp)

I can eliminate the hum entirely by connecting a 1:1 isolating transformer near the preamp output and ensuring that the ground leads never form a loop on their way from the output sockets to the transformer. Originally, in the isolating tranbsformer that I got, the ground leads where connected on either side and there was still some hum that way. Cutting that connection on the side that the preamp output was connected to eliminated the hum entirely.

What I think is happening is that the ground leads in the cable between preamp and poweramp are forming an induction loop and teh magnetic field from the largish transformer of the poweramp is inducing a small voltage into that loop. (like 0.06 mVpp). Since this is exclusive to the common ground and not common-mode with regards to the the input of the preamp it is "seen" by the preamps input as a voltage which is to be amplified by 60 dB (1000x) and becomes 60 mVpp at the output. When the preamp is running at lower gain settings, its not such a big deal because it isn't being amplified that much.

I can measure that the poweramps transformer can cause that level of induction by building a loop from a length of wire and a connecting the ends with a smal resistor (15R) and measuring votage over that resistor with an oscilloscope. Based on how I position that loop relative to the transformer, I am able to measure a 50 Hz hum signal of up to 2 mVpp (5 mV per div is the most sensitive my oscilloscope can go so it's hard to see but it is there for sure)

So I think my theory about the induction is pretty solid at this time and I have ruled out more classical ground loops. Especially since the whole effect can be simulated without any galvanic connection between the two amps and the turntable completely out of the picture.

Does that theory make sense though from a practical engineering perspective froim people with more expirience?

If it does make sense, what can be done about it? Options I am thinking about:
- More physical distance between the untis doesn't cut it because the cable still has to come near the poweramp and that's when the trouble starts
- Usinga torodial transformer in the poweramp so there is less of a stray magnetic field
- Making the output-transformer solution at the preamp side more permanent by adding high-quality transformers (e.g. Lundahl LL1527) at the output. That would have the added benefit of being able to offer symmetric XLR outputs on preamp

Anything else you guys can think of? Anything I omitted in the description that could help explain the situation? Just let me know and I'll try and elaborate...

Cheers,
Lars

FS: Lower Price ...Pair B&C 6MD38-8 midrange drivers BNIB

BNIB, and only taken out for photos. The tabs and screw holes show they have never been mounted or plugged in. $100 and YOU pay the shipping.

H All,

I am selling my DIY AMT tweeters. I have 8 available and I am selling them for 285 USD (or 240 EUR) each.
I will ship anywhere at cost of the buyer, I am located in The Netherlands.

I am not with a company, you will be buying from me as an individual.
This means I cannot provide literal warranty, but if anything breaks I can repair the unit or I can send a replacement diaphragm. The diaphragm can be replaced by removing the back box and loosening the 4 screws inside. The diaphragm simply slides out.
Pairs will be matched by picking the closest pairs out of the 8 pieces. The maximum tolerance over the whole batch is +/- 0,5dB.

For detailed specifications please check the datasheet. The datasheet can also be downloaded from the attachments. I will list a couple of key features and specifications for who's in a hurry.

Features:

• Very low distortion, roughly -50 dB at 1W/1M.
• Very wide and smooth horizontal dispersion. -2dB in a window of 40 degrees!
• Somehwat narrow, but very smooth vertical dispersion.
• Usable from 1,3kHz with low distortion.
• Very flat impedance.

Specifications:

• Nominal impedance: 4 Ohm
• DC resistance: 5 Ohm
• Inductance at 1 kHz: 0,02 mH
• Effective piston area: 9cm²
• Actual piston area: 39,9cm²
• Moving mass: 2 g
• Free air resonance: 1,3 kHz
• Sensitivity, 1W/1M: 86 dB
• Force factor: 1,99 Tm
• Magnetic flux density: 0,67 T
• Long term- power handling: 20W
• Short term- power handling: 50W
• Weight: 0,76 kg

Project background information:
Developing transducers and audio electronics is a hobby of mine. I wanted to see if I could develop AMT's that could be paired with Purifi Audio's woofers in a 2 way nearfield speaker. I could've just bought parts for two units, but then I would've ended up with a 2000 euro pair of AMT's. I said F* it, lets spend a little more to bring the unit price down alot, and see if I can sell the extra units to get back the investment. This is the first time I'm doing this, I want to see if it is something I can repeat to save money for more projects.

Design philosophy:
AMT technology seemed like a good candidate for a low distortion, constant directivity system, but most available AMT's have a bottleneck that cannot be fixed. Alot of AMT's have a quite large diaphragm, causing bundling of high frequencies. The narrower and shorter AMT's are better with dispersion, but are limited by rolloff and distortion under 3kHz. The AMT's that have both good dispersion and low distortion often cost more than 500 USD each (Mundorf, Eton). I decided to try to shift the compromises to the things that are less important for a 2 way nearfield, or to things that are fixable.

Frequencyresponse:
The frequency response is not flat, but it is smooth, and the rolloff is roughly -3dB at 1,2 kHz! There is one bump that should be filtered out, this can easily be done both actively and passively with a wide bandwidth notch filter at 7,5 kHz.

Dispersion:
To achieve wide and smooth horizontal dispersion I decided to make the diphragm narrow, 20 mm! Vertically the tweeter is also quite short, 45 mm. There is some bundling, but the dispersion is very smooth. The smaller diaphragm surface causes the sensitivity drop at the lower end of the tweeter.

Distortion:
To achieve low distortion over a wide bandwidth I decided to go with a realatively thick kapton membrane material. The membrane thickness causes the sensitivity drop above 7,5 kHz. The resulting distortion is very low, even at 1 kHz and 64W (-30 dB)!

BTW. This tweeter should be perfect with a waveguide because of the drop in sensitivity where the waveguide causes gain. Also, the wavefront is planar.
The back box is easily removable for dipole use, but I have no specs for it like that.

I’ve been left to my own devices and started looking at circlotrons. Mainly out researching CF and noise reduction.

Broskie shows a CF zen with Compliant CCS and that became inductor based, and then I thought about doing a differential circlotron with inductors to overcome the need to have a ground reference (although this ruins the idea of ground noise injection at the anode via the ground references cccs).

So would the architecture above work? I don’t see much difference to a LPF so I was wondering if a cap between the anode and ground would allow ground noise in too this cancelling at the load. (I’ve not thought this but though just now).

Hi,
I'm a novice builder, having successfully completed one ACA on my own. And it sounds great. I really enjoyed building it, and I've been reading lots and lots here to learn more about this hobby. It appeals to my inner need to ponder multi-variable problems and tradeoffs. I'm now considering my next project, and here are some of the parameters I have in mind:

1) Monoblock amps; I've always wanted a pair of big monoblocks.
2) Balanced inputs: I want to run the amps near the speakers, potentially with long(ish) runs from the pre. I'd like a "true" balanced design to take advantage of common mode noise reductions. My current pre amp (Schiit Freya) has balanced outputs, 600 ohm output impedence.
3) Boards available from diyaudio.com. I feel like I can build off a schematic but I am a guy with a soldering iron, not a designer and most definitely not an EE. I need to work from an established BOM. I want to use the available PSU and soft start boards from the store.
4) Output in the 50-100W range, I don't want to do cascoding or anything exotic (see #3) but I'd like a little more headroom than the ACA offers. I'd like to build with some degree of conservatism and not push any component too hard.
5) Budget. I'm willing to make the investment in the chassis (either 4U or 5U as needed) and other stuff to make this happen.

Speakers? Well, I'll be getting new ones soon (in the process of moving). I'm interested in going to high-efficiency, either horns (Klipsh/JBL etc) or full range drivers like Zu or similar. I'm also toying with the idea of using an active pro-x-over like an Ashly xr-1001 to run stereo subs (another reason to want balanced connections) down the road. So, I don't need a ton of power, but I feel like I'd like to try something more than a pair of ACAs would offer.

Musical tastes: wide variety but I really enjoy live concert recordings, the Dead, DMB etc, solo piano, blues, solo guitar, also hard bop jazz, some vocals. Very little orchestral.

Knowing all that...what boards should I be looking at? It seems like the BA-3B is an option and I've seen threads on the F5, but making a balanced version of the F5 looks perhaps more complex. What about the Aleph J? Welcome any thoughts or advice from the learned members.

Hi All,

I did a search and didn't find ant similar thread about oscillation.

I built the Pass Zen 4 and noticed a 100mVpp oscillation at output either with/without load around 43kHz with 2nd harm. 96kHz.

It looks weird it is close to 48k but I'm sure no others gear is hooked to the main that can generate the noise.

Power supply not an issue as I use a Farnell linear psu and double checked that the regulator around Q5 is not an issue by bypassing it. Did anyone experienced similar one?

If I increase C12 to 10pF it decreases to 50mVpp but no benefit if I increase more ....any hint? Thanks!

I'm looking at drivers for a budget 3-way (1" tweeter 5" mid 8" bass), I'd like to ask if folks generally spread driver costs equally or does it generally make more sense to skew one's budget toward a specific driver, and if so, would that more likely be the bass, the mid, or the tweeter?

Put another way, has anyone ever designed a speaker where you splurged on one driver in particular?

The reason I'm asking is cause I've seldom heard a budget tweeter that knocked my socks off; there seems to more value to be had with woofers and mids but tweeters not so much.

RMAF is gone. I always hoped to go one day, I guess I should have gone when I could.

Rocky Mountain International Audio Fest - High-end Consumer Audio Show

I am looking for PCB of baby Aksa55 (Baksa),
If you have this and it's lying in a drawer, I'd be interested.
Thank you
Liva

Hello everybody , there is one thing I would like to try and thats using cheap power supply pcbs from china which are available at both 24 volts at 6 amps and at 36 volts at 5 amps. Of course they cannot compare to a supply using a toroidal transformer but they do save a lot of money and they are stabilized.
Plus they are small and compact at a cost of only a few dollars........
But , as far as I know , they have a nasty ripple on their output which needs to be filtered out.
Can anyone enlighten me on this subject please?

I feel so damn stupid. I must have ripped it of while trying to slide the board into to an aluminum extrusion. 😱



I've looked everywhere but can't find it, so now I'm hoping someone could help me identify this component so I can solder on a replacement. Hopefully the amp will still work.


Please refer to the attached pics.

Hi All,
I’m in need of advice on midbass drivers that will work in small sealed enclosures please?
They will be used from approximately 120hz up to around 500hz, ideally 2ohm, as my amp will do 80w rms into 2ohm but only 40w into 4ohms.

Many thanks
Jason

Hello,

Maybe someone have some experience to share or builds with "The Box 15LB075-UW4" I found them at thomann.de. T/S parameters are not promising, but the price of 55 EUR is appealing. Is it possible to find something better at this price and maybe there are more shops in europe that has a variety of speakers to choose from?

I have attached t/s parameters and one of the simulations I did. Is there a better way to do it then a .straight horn?

Hello
I would like to buy some NOS RCA 5691 / 5692 tubes if any available over there.
EU preferred but No problem if they come from overseas.
Thank you.

Hi,

I have decided to built a magnetic driven planar speaker.

Got most of the parts, and the design is illustrated below. A perforated steel plate as I have used in my ESL projects, with 10x10x40mm neo magnets. A alu frame in 1/2" x 1/2" square alu tube provides stiffness and spacing between diaphragm and magnets (distance will be 2,7mm + 1mm vhb tape.



Diaphragm will be 6micron mylar, with 9mm wide CPC alarm tape as conductor (0,6 ohms/meter resulting in a 5,4 ohm dc resistance I should imagine.

Horisontal spacing between magnets will be 15mm, and 10mm vertical spacing.

Outer dimensions of the frame will be 190mm wide and 1000mm high.
There will be 8X18 = 144 magnets pr speaker.

As the back plate is bigger than the diaphragm, it will be easy to mount baffles, and easy to add a ribbon tweeter if I should decide to do so later.

I am very exited by this project, it should be easy to build and hopefully give more satisfying results than my ESL attempts has given so far.

Any comment to my idea? Should i make it wider, bigger/smaller distance between magnets, distance between magnets and diaphragm?

Theese magnets cost a fortune, so I am reluctant to increase the number of magnets in the first test (I have 205 in stock)

All that remains now, is to unite theory with practice and see how it turns out!

Regards,

Bent