Hey guys! Excited to be here. Have spent 15+ years on the Car Audio forums. And have ended up on this site more times than I can count in my quest for knowledge. So figured I'd join!
I've build a few home speaker's. With the empty nest, is time to build some more. Currently jamming a Scan/Seas combo for my reference monitors. The DD is whole other story. Also currently building a system in my 65 Mustang.

Love all the collective knowledge. I look forward to being a contributing member. Cheers Jared

I am planning a build of a large 4 way speaker (3 way with built in sub....) And the biggest headache so far is the subwoofer section. I live in Thailand so besides locally produced pro drivers and car subs there isn't a lot on offer or it is way overpriced. Now I saw these automotive 12" drivers that look good to me. The measured specs are actually really close to the Dayton UM12-22. Slightly heavier cone, a little less xmax and a db less sensitive.

BUT NOW I HAVE FOMO because they are on sale for about 50usd each and I am planning to use 8 of them. I almost pulled the trigger and then noticed the spider looks like it doesn't have ventilation.... Is that cause for concern?

Any opinions on these drivers? Anyone who as experience with these?

Can anyone suggest a better option than 4 x mb quart pwm304 12" subwoofers in 300L sealed? Manufacturer suggested box would only be 140liters. (35liters for one driver x 4) Is that in order to fit it into a car or for best sound quality? In 300liters QTC is 0.79, in 140liters QTC is 0.96. Wouldn't the larger box sound better?

Measured Specifications

Revc= 1.990 ohm
Fo= 24.294 Hz
Sd= 0.0491 M²
Vas= 55.4L or 1.958 Ft³
Cms= 0.162 mm/N
Mmd= 258.719 g
Mms= 264.975 g
BL= 10.843 T•M
Qms= 3.673
Qes= 0.685
Qts= 0.577
Levc= 0.910 mH
No= 0.112%
SPLo= 82.522 dB
EBP= 35.46

https://www.pasmag.com/technology/test-reports-reviews/mb-quart-pwm304-subwoofer

PMA CFA - current feedback power amplifier with +/-25V to +/-55V dc supply range

Intro

This project has started in the beginning of 2016 for the reason that I was interested in a current feedback topology (CFA) behaviour. The current feedback concept is well described in Renesas company application notes. For those who are interested, I recommend to download the application notes that I have linked below. I could hardly say anything more.

https://www.renesas.cn/cn/zh/document/apn/an9420-current-feedback-amplifier-theory-and-applications

https://www.renesas.cn/cn/zh/docume...ersus-current-feedback-operational-amplifiers

The goal was to design a simple and robust amplifier that would be able to drive difficult loads, would be stable and would have balanced time and frequency domain characteristics. The lowest nonlinear distortion was not the design goal, just to keep it inaudible.

Another goal was to make it working with a wide range of power supply voltages, here namely from 2 x 25V to 2 x 55 V.

The amplifier, with working title ACCE3, has been reliably operated for years, without a single problem.

Circuit design

Amplifier schematics is as follows. The circuit is complete, with part numbers and values.



Q1-Q4 make a CFA input stage, with low impedance inverting input into R14/R15 common junction. Q5-Q8 make a VAS stage, with quite high current through Q5/Q6.

Output devices are 3 pairs of robust OnSemi MJL21194/93. Drivers are MJE15030/03. Similarly as in case of my PA4 amplifier, the rugged and reliable amplifier was my goal.
Supply voltage was tested at 2 x 25V and 2 x 55V, with no change in the circuit. The amplifier can easily drive 2 ohm load with 2 x 25V, staying completely safe. With 2 x 55V, I would recommend for the load impedance not to be lower than 3 ohm.

IC1, DC servo, is to be OPA177 opamp, for the reason of excellent DC parameters and for the reason of low idle current of 1.3 mA. This is necessary to cover wide supply range of 2 x 25V to 2 x 55V without unwanted high voltage drop across R32 and R33.

The amplifier is stable without an output coil, however, for safety reason I would recommend to add a parallel R//L combination 1uH//6R8 behind the X2-1 (X2-2) output terminal.

Construction notes

The amplifier is strictly dual-mono, channels do not share any common ground point, so no ground loops are created. The power supply has one transformer with separated secondary winding for left and right channel. It has separate center-tapped bridge rectifiers with capacitor banks of 2 x 14100 uF for each channel, as can be seen from the photos.

Voltage drop across 0R22 emitter resistors (R25 etc.) is set between 15mV - 22mV, which makes idle current per transistor equal to 68mA - 100mA.

Photos of the amplifier

The amplifier with 2 x 25V dc supply built in my old Fischerelektronik 19” 3U 20+ years old prototype case can be seen below:



And this is the more detailed photo of one module built in another amplifier with 2 x 55V PSU.




Basic specifications

•Output power 2 x 200W/4ohm with 2 x 55V supply, 2 x 40W/4ohm with 2 x 25V supply, THD 1%
•Frequency roll off (-3dB) 225kHz
•Harmonic distortion <0,02%/1kHz/100W/4ohm (2 x 55V PSU)
•CCIF 19kHz+20kHz 0,01%/30W/4ohm (2 x 55V PSU)
•Rise time of step response 1.4us
•Gain 27dB
•S/N ratio 94dB/2,83V/BW20kHz/linear, 114dB at full swing (2 x 55V PSU)
•minimum load impedance 2 ohm resistive/complex with 2 x 25V supply, 2 ohm resistive or 3 ohm complex with 2 x 55V supply

Measurements

Amplitude and phase response within 20Hz – 40kHz range



We can see gain of 27.1dB and amplitude and phase response flat in the audio band.

Step response



Rise time (10% - 90%) of the step response is 1.28us when measured with the fast function generator with 10ns rise time. This indicates to 273kHz/-3dB amplifier bandwith.

Response to 10kHz square



Response to square wave does not depend on signal amplitude, it is level invariant, thanks to CFA topology. This was measured with a generator with about 2 us rise and fall time.

Distortion measurements with 2 x 25V supply

THD+N vs. power at 1kHz into 4ohm load



I do not have an autoranger, so this was measured with 2 settings of ADC input range, 10V and 60V. This is for the reason that at 60V range the system noise is higher than amplifier noise and thus we get too high THD+N numbers at low power, due to measuring system intrinsic noise.
We can see that THD = 1% is at 40W and that the distortion knee is about 27W.

Comparison of THD+N vs. power at 1kHz into 2.2 ohm and 4 ohm load (and comparison of measurement vs. simulation)

measurement simulation

THD+N = 1% is at 40W/4ohm and 60W/2.2ohm. There is no extreme rise of distortion into 2.2ohm load, the amplifier has no problem with it. And as always, simulated result is more optimistic than the real life result.

THD vs. frequency at 30W into 2.2ohm load



Distortion stays below 0.1% up to 22kHz. Below 100Hz we can see effect of heavy power supply load (ripple) due to high load current.

19+20kHz CCIF IMD



Overload recovery according to IEC60286-3 (overload recovery time)

First. the definition. I find this test extremely important!


and, the measurements with 20Hz and 1kHz signals



Distortion measurements with 2 x 55V supply



Measurements with 2 x 55V supply were done 4 and more years ago, with another measuring system, that was unable to make stepped THD and THD+N vs. power measurements properly. Please let me show only 100W/4ohm/1kHz spectrum.


Conclusion

The amplifier has proven to be reliable in operation since 2016. It is robust and able to drive difficult loads, while tested into complex load and R//C load.

https://pmacura.cz/pmacfa.htm

_____________________________________________________________________________________________________________________________________________________

Edit: Gerber files and BOM

I am attaching Gerber files and BOM which applies to the amplifier shown in the photos above and which were used for PCB production. Please note there is one wire jumper on the PCB shown in the pdf brd file. Gerber files updated with vertical power transistor packages!

Hi! , is it a good practice to add a small value capacitor ( for " better high end " ) in parallel with the feedback cap? , what value would be " best " ? .
What about the input cap in parallel with a small one ?.

Peter Schickele passes away at 88, a source of endless musical amusement and a serious composer.:

From New York Times obit:

He wrote more than 100 symphonic, choral, solo instrumental and chamber works. But he was better known, and celebrated, as a musical parodist. Who can forget the “Concerto for Horn and Hardart”?

Under his own name, Mr. Schickele (pronounced SHICK-uh-lee) composed more than 100 symphonic, choral, solo instrumental and chamber works, first heard on concert stages in the 1950s and later commissioned by some of the world’s leading orchestras, soloists and chamber ensembles. He also wrote film scores and musical numbers for Broadway.
His music was performed by the New York Philharmonic, the Cleveland Orchestra, the Lark Quartet, the Minnesota Opera and other notable ensembles, as well as by the folk singers Joan Baez and Buffy Sainte-Marie, for whom he wrote arrangements.

But to his resigned chagrin, it was as a musical parodist in the tradition of Victor Borge, Anna Russell and Spike Jones — Mr. Schickele’s particular idol — that he remained best known.

For more than a half century, through live performances seemingly born of the marriage of Mozart, the Marx Brothers and Rube Goldberg; prizewinning recordings; and even a book-length biography, P.D.Q. Bach (“the only dead composer from whom one can commission,” Mr. Schickele liked to say) remained enduringly, fiendishly alive.

Leaping from Mr. Schickele’s pen in P.D.Q.’s name were compositions like the “No-No Nonette,” the cantata “Iphigenia in Brooklyn,” the “Unbegun” Symphony and “Pervertimento for Bagpipes, Bicycle and Balloons.”

With these and myriad other works, Mr. Schickele, who billed himself as P.D.Q.’s “discoverer,” gleefully punctured the reverent pomposity that can attend classical-music culture.

It was P.D.Q., after all, whose work won four Grammy Awards to Mr. Schickele’s one. It was P.D.Q. who packed some of New York’s foremost concert halls for decades of annual Christmastime concerts. And it was P.D.Q. who, unbidden, could rear his head insidiously at performances of Mr. Schickele’s serious music, with audience members who had come expecting belly laughs sometimes walking out in bewilderment.

Greetings friends, I've had a productive couple days and completed work on a compact 6DJ8 Headphone Amp. While I became aware of the project thru @Suncalc I decided to use SS rectification and built the circuit as described in the DiyAiudioProjects website, with the Antek AS-05T160 (160v@150mA) planning to adjust the dropping resistors in the power supply to achieve the 135-150 voltage spec'd in the schematic. Heaters use AC, both coils paralleled and artificial center tap to Ground. It's built in a Hammond 1458VE3 enclosure:



The amp powered up just fine, I saw a little over 200v with no tubes installed. Drained the caps, installed a pair of tubes and fired it up with some headphones plugged in but no signal. The voltage leaving the power supply is about 166v, so I need to increase the dropping resistors. But I heard a savage hum coming from the headphones while they sat on the bench. Not loud enough to break em, but certainly too loud to use the thing. Sounds like 60Hz but I don't have a dummy load built so I can't say for sure. Hum was equal across both channels in the headphones.

As you can see, the open-frame OTs are rather close to the PT. Maybe I could put a steel cover around the PT.

And the leads from the OTs pass under the volume control pot and cross the input leads, but I'd expect any noise from that to be high-pitched...

any ideas, thoughts welcome. thanks for taking a look.

w

OK, I'm going to give this site another shot, because after all, I did pay to support it. I know that doesn't apply to this particular post but I am trying to make peace here so that I can get on with things and hopefully not have people jumping down my throat about things that aren't really their business. Moving on (hopefully), My question here is, and I hope I'm in the right area, if not, apologies and please let me know in a civil manner thank you, are powered home theater subwoofers, particularly those made by decent brands such as JBL, Klipsch, and so on rated in RMS or max power?

I'm asking because I have a JBL 12" subwoofer that's rated at 350watts but I can't find anywhere if that's an RMS rating or max and it has a cooked amplifier. I tested the woofer on a lower powered amp from another powered sub that I have. It's only a 150 watt powered sub but it was enough to move the woofer to confirm that it's good.

I'm by no means an electronics expert, as some of you may have figured out from other threads, but I am able to do some testing with a meter and I am capable of doing some soldering. I found a spot on the PCB that looks like it got really hot by the brown burnt looking spots, and there were 2 resistors, 3 capacitors, and 2 3 legged components marked Q2 and Q3 that were involved in the event that caused the heat, which I am assuming is the cause of the amp being fried. I carefully desoldered all of them and observed that the copper sheeting used for the pathways and the coating that adheres it all has been compromised by the heat and there is a lot of charred residue left from the components so whatever caused the meltdown did a pretty good job of destroying the components and the board so I'm calling it toast.

So I'm looking at options for a replacement amp board or even an amp with it's own enclosure that I can install inside the cabinet and construct a panel to seal it up so that I can get the sub working again. I am not the one who cooked it, I bought it used for parts at a huge discount and am trying to get it working. However in my search for an amp I am trying to determine a good power match for the woofer and I have been unable to get a clear understanding of what I should be looking for. Should I get an amp rated for 350 watts max/peak, or 350 watts RMS?

It's not JBLs top tier equipment, it's an older model from a box store home theater series known as the Venue series. I have all the other speakers in the series. I realize they are nothing special but I've enjoyed collecting them, they do sound decent, and it's what I'm choosing to use for my dual 7.1 HT setup which is complete, save for this sub and a second TV that I may or may not add later.

If all you are going to do is criticize me in any way or otherwise be a D, then please refrain from comment. If you are willing to help me out here, please do and thank you in advance. I'm saying this because my first 2 experiences here have been less than pleasant and I don't feel that I deserved it. That may not be agreed upon and if that's the case, I apologize for whatever it was that ruffled feathers but I'm just a guy who tries to make something out of next to nothing because I don't have a mountain of disposable cash so I'm usually working with components that need some TLC or maybe a little more but I don't think I'm doing anything wrong by that and the reason I come to places like this is to gain knowledge and that's why I will usually donate or subscribe to the premium service, however I feel that I was judged before the trial started by a few members who evidently think that I'm supposed to be a certified engineer before doing this but we all have to start somewhere and I don't have the funds for formal electronics degrees, nor do I have the time. I'm not stupid so I don't work on things while they are plugged in, I understand that capacitors can hold a charge for some time even after the unit is off, unplugged, etc. and I don't care enough about any of the components I work on, which wouldn't be of any significant value to me or anyone else, to worry much about tossing them in the recycle bin if what I'm trying to do doesn't work. Thanks for your understanding, and please, if you must be critical, can you at least do it in a civil manner?

Hello. Appreciate any input if anyone has the time.
I have got Klipschorns, 1210s and a mastersounds rotary mixer.
I've had valve amps before and have liked them, but have had a couple of sets.
Looking for something that works with the above, make decent use of the bits and bobs I already have.
I have a short attention span so general online searching lead me nowhere.
Anyone who has any good recommendations, much appreciated.
Peace.

I measured around the digital input with a multimeter. The result was obviously a fatal damage....
No matter which input is selected, the DACs input does not lock.
Independently from the volume, while no input is locked, there is an output - see plot.

The 74HC244D (or 74LV244D) has been replaced, but still the same problem.

Do you have any idea, if this can be rescued?

Best wishes
Michael

SOLD

i got this amp today it worked for like 5 to 6 mins then turned off.
it sounded really good.
i have checked the d.c. offset and it was set to about 6 to 7 mV on both channels
the thermistor reads about 75ohms
so i think its the Protection chip (z501) is broken (it only sees temp and d.c. offset)

what do you guys think?


Thanks for any help



https://www.manualslib.com/manual/798449/Arcam-Alpha-9.html#manual

Hi again. I have an issue with the sound of my latest amp. It has overly strident high frequencies. The amp boards are full of small value film caps which are most likely causing it.

I preferably want a relatively warm, smooth sound, so I was thinking about using Russian oil caps.

The amp in question is an Onkyo M-505. Below is the schematic.

Hello, looking for advice on my next set of speakers.
System electronics is a NAD 7125 receiver (similar amp to the famous NAD 3020), vintage restored Sony CDP-101 CD player, AKAI GX-625 reel to reel and Pioneer PL12D turntable - some middle of the road classic 80's hi-fi, listening to old rock, Dire Straights, Leonard Cohen etc.

The sound is "satisfactory" to my 60 year old ears through a pair of well travelled Mission model 70 (original, not the MK II) speakers, now maybe 40 years old. Believing the speakers are the weak link, and pondering if to update & replace them. I am from Europe originally, and OK with a "bass lite" sound, liking clear midrange and crisp treble. Find US speakers too "bassey", and try to avoid Chinees plastic "rubbish".

Looking for an upgrade with European speakers, second hand, but newer than 1980's, with a budget of $300 to $400 ish.
Replacements for the Missions that come to mind from reviews are the B&W CDM-1 SE or NT, or Focal Cobalt 806, the 806S preferably. Like to keep to a similar size of ~15" high by 8" to 10" wide, and 8" to 12" deep for use with existing stands. Either no port or front ported for room position flexibility. "Music" room is 11' by 16' with 8' ceilings - it's my man cave/spare bedroom with speaker positioning non ideal.

Buying on eBay clearly not "demo-able", and hard to say "no" if have travelled for a Craigslist advert. So have to buy somewhat "blind" and on recommendations.
Appreciate ideas on the suitability of the B&W CDM-1, Focal Cobalt 806S, or other European classic speaker suggestions, thanks floridaclear

Complete set of Speaker Builder Magazine 1980-200. Condition is very good to excellent. I can ship USPS media mail for about $25. Make me an offer. Free local pickup in Santa Cruz, CA.

I have checked the fuse. No light no nothing.
can anyone help please.

For sale a pair of magnificent true bass woofers Eton 11-581 Hex 11" woofers. hey wer kept on the shelf for long but I won't use them.
installed in speakers like Avalon Time (and others), Usher Be 10, Usher Be 20... highest quality.
Very efficient, veryfast impulse and dry punch.

Like new. Never used, just measured one of them.

Asking 350€ + PP fees + Shipping for the pair.

For quite a while I was happy with my excellent modified Stingxer F1 but the question,
if this quality of sound was possible with a multi channel setup never left my mind.
When I one day saw Brooklyn II boards pop up on ebay I was getting exited.
I searched the net if there was an adapter board available. Lo and behold I
found one at Aliexpress. Man this is heaven for computer audio.
$120 for the Dante board and $80 for the adapter is not significantly more
expensive that a Singxer by itself.
Dante not only sounds better than the Singxer USB DDCs but it is rock solid.
No hick ups, no pops, no clicks.
8 channel output via I2S is just a dream come true for the diy audio world.
The only thing that I need to figure out is how to get my AK4490 an AK4495
dac boards to accept serial control mode because data is not sent out
on a left/right stream over one data pin but as two separate streams over two
data pins.
Here is my set up so far:


If anyone can help with the serial mode problem I would appreciate it.

Greets,
Klaus

Hello,

I need a pair of goof quality 7-8 incher for a bass in 3-way. These are my favourites Dayton RS225, Wavecor WF223, SB23NBACS or Satori MW19. Price up to 120 EUR per pair.

Will consider different driver of similar quality as well.

EU offers only please.

Hello there,

Just new in here..

I currently have a Douk Audio Dual-Tube Preamp which has a B9A base, where both the sockets are close to each other as shown in the Pic.



So my concerns are :-

1st of all is it even technically possible to roll the tubes to the 7193 ? If so then it should be 7193 tube for each channel i.e. a total of 2 tubes would be sufficient ? Or i will need dual for each channel so a quad setup ?

Regards.
~R

I just acquired a pair of Threshold SA-1s brand new sealed in their original boxes as part of a larger purchase of NOS Threshold gear. Given these are 34 years old or so, is there any harm in bringing them up slowly on a variac one at a time to test? How slowly should I go? Power consumption will likely be around 400W at line voltage. I will likely replace the main filter capacitors any way, but I'd like to confirm the amplifiers work before I get inside of them and start replacing filter capacitors. Any recommendations on filter caps I should use? On paper, EPCOS/TDK seem to be the best ones currently available.

Ciao a tutti, sono un nuovo utente.
il mio NAd 3266 entra in modalità protezione dopo circa un minuto.
Cerco aiuto per ripararlo, ho fatto vari controlli e misurazioni.
Il problema è sul canale sinistro, la resistenza R483 si scalda troppo e se provo a regolare la corrente di riposo con VR103 tra TP1 e TP2 non si muove, rimane ad un valore intorno ai 5 volt.
Quando lo spengo sento un rumore tipo scarica sugli altoparlanti, pensavo fosse un condensatore che perde ma sono buoni, almeno quelli sulla catena del canale sinistro.
I transistor sembrano buoni, ho invertito anche i finali e il problema rimane.
Allego lo schema.
Qualcuno può aiutarmi?

Translation:

Hi everyone, I'm a new user.
my NAd 3266 goes into protection mode after about a minute.
I'm looking for help to repair it, I've done various checks and measurements.
The problem is on the left channel, the resistor R483 heats up too much and if I try to adjust the quiescent current with VR103 between TP1 and TP2 it doesn't move, it remains at a value around 5 volts.
When I turn it off I hear a discharge noise on the speakers, I thought it was a leaky capacitor but they are good, at least the ones on the left channel chain.
The transistors seem good, I also reversed the finals and the problem remains.
I attach the diagram.
Can someone help me?

I have Two Toroidal transformers, 400VA , 120V primary and 2x45 secondary with shield cans.
They are Audiograde type from Toroidy.
They are ideal for a power amplifier with +/-60V supply, you can use one for each channel in a dual mono configuration.
Asking $140 USD for both plus shipping.

2x LL 1620 - 40 mA output transformers available, and in good condition. Asking $350 for the pair. Buyer to pay shipping. Thanks.

I want to measure/adjust the idle current of my old HK Avr80 receiver. It uses a dual resistor (3 legs) with 0.18 ohm value. Service manual says target value is 7.2mV (20mA). Should I measure the idle current across from the middle leg to one of the outer legs of the resistor or should I measure it across both end legs of the resistor? The manual didn’t specify where to connect the test leads of the multimeter. Thanks for the help!

Can I use two identical power supply chokes in parallel to double the current rating? Halves the resistance and doubles the reactance, right?

Thanks, S.

Hello, I have a speaker whose parameters I sent in the photo. I want to make a scooper box and I wanted to check in the hornresp program whether it makes sense in this scooper box, but I don't know anything.

SOLD!

Selling 2 complete boards with IPS and output transistors.
Fully functional and with matched transistors. All components bought from fireanimal (Andy).
Built for +-70VDC.

Payment through Paypal is possible. I will send well boxed.

Price 500€ for both boards

Looking to buy a few of Mark Johnson's Soft Start boards for some amps I want to experiment with.

I am located in Houston, TX.

Greetings everyone.

I have a couple questions regarding the labeling of Transistors and second inconsistent hfe concerning Saken Transistors bought from Digi key.

# 1 I have noticed that sometimes you will see the traditional white lettering and sometimes Laser etched, specifically on Sanyo and Hitachi and even some Toshiba.
That being said I have some small signal Transistors from the three manufactures I mentioned.
I have even seen them in NAD Rotel Onkyo long story short should I be concerned over this is it true they did use laser etching??

# 2 I recently bought some Sanken Transistor's from Digi key. 2SA1695 2SC4468-and others when checking for the Hfe value I noticed there was no consistency.
Also, three of the Transistors checked as Germanium and some only had an Hfe between 6 & 7 so I'm returning them, just curious if anyone else had any problems.

Thank you for your time and consideration everybody I'm fairly new here and this seems like a very education site!

Google doesnt come up with anything usefull.
All i can find is a 3 page so called service manual, which is nothing of the sort.
No diagrams, no parts list, not adjsutments or measurement page.

Thanks in advance.
p.s. did a search on here and nowt either.

I am a radio guy with little audio knowledge. I have transformers from a 1960s era ham radio RF amplifier that I would like to sell. I know they are of value to the ham radio community. Are they usable and of interest in the audio tube amplifier world? Specs below, photo attached. The 5-20 Swing Choke in the photo is also available but likely of little interest.
Thanks, Pat
Minneapolis, MN
===
TRANSFORMERS
PRIMARY SECONDARY VOLTS Amps TYPE
115 5400/5800/6200 CT 0.250 High Voltage
115 10 6.0 Filament with Electrostatic shield output.
115 2.5 CT 10 Filament

Hi,
I've been using the Focusrite Fcarlett 2i2 2gen interface for measurements for some time now.
The card seems to measure well. All the results from RMAA are at a similar level to the results I found online. I am posting a THD loop-measurement made with the RMAA.

I recently connected the output of the card to an oscilloscope (one of the differential outputs or the output from the differential to single ended shorting adapter - no difference).
To my surprise I saw a very noisy waveform. I'm posting screenshots from the oscilloscope for a 1kHZ -0.5dBFs waveform and for the output with no signal. As you can see, the noise reaches 200 mVp-p. I also include FFT spectra of these signals, where you can see that the noise spectrum is shifted to 30-40kHz which explains the good measurements in RMAA.

Is this normal for this interface?

I took measurements with the card connected to a laptop powered from the mains and battery - no differences

I will add that the output signal from other sources I own is clean in the same measurement setup .

Could someone confirm these results on their unit?

Marek

Can anybody help me, the cable, analog or digital, is passing through a wall and runs next to other cables, even powercables. Does anyone know if there exist a converterbox 24bit/192khz to optotoslink?
Tommy

I have a pair of old VMPS RM30 speakers that I am thinking of converting to all active - It has Aurum Cantus GS2i tweeters. I was looking at alternatives and I found this warning about a Fountek Ribbon "Ribbon tweeters should always be used with a passive crossover! The ribbon is a dead short to your amp."

Is this true?
If so, what can I do to prevent this?

Hi Guys,

After building a small HV power supply regulated power supply to eventually build a tube preamp chassis to couple to my Aleph J. I found out it might be a better idea to ask some questions before I move to a pre-amplifier circuit choice.

Currently, I drive my homebuilt Aleph J from an IPhone 5. I know its dated but it sounds good to me and seems to measure well into low impedance loads:

https://www.kenrockwell.com/apple/iphone-5/audio-quality.htm

Using high quality 320k mp3 I found that I need to keep the volume at 80-100% or a room filling sound with the Aleph J and generally its not really loud enough and a real Eureka moment came when a friend brought is Sony headphone amplifier over and plugged it in and WOW it really came alive.

I started looking into the specs of the Aleph J:

Input Impedance 242 Kohms (RCA input)
Input for 25 watts output 1.5 volts

Is that 1.5 volts RMS or peak-to-peak?

I already put some time to build up a chassis with R-CORE transformer with a HV and LV regulator board for this circuit thinking it would be appropriate but then I re-read Aleph J specs and its input impedance is over double of that stated by this design (100K vs 242K). What should I do now lol?

This was recommended in the RCA Radiotron design guide in the 60's as a 12AU7 preamp design. I wanted to use 12AU7 specifically for this because I was gifted about 30 NOS 6189W tubes from a retired military technician, all in original boxes. Is it still a viable design to use with the Aleph J or other amp designs? If not, what preamp design is best coupled with Aleph J? I already built the HV/LV power supply and really want to use the tubes I was gifted. Any suggestions or ideas is really appreciated!

I've been thinking about making a dipole unity horn.

Something I've noticed with nearly all of the "modern" dipole implementations is that the baffles keep getting smaller and smaller and smaller. 20-ish years ago, it was fairly common for dipole speakers to have wide baffles:



I am no expert at dipoles, but as I understand it, the reason that "modern" dipoles have narrow baffles is because it "pushes" the dipole peak to a higher and higher frequency. IE, if you have a baffle that's 30cm wide, the dipole peak may happen in the passband of the midbass or even the midrange. (I am too lazy to look up the math on linkwitzlab dot com.)

So here's my question: how much of an issue is this?





For instance, four years ago I was working on a project that used four midbasses with a waveguide in the center. I'd intended to seal the box up, but I measured it before I got to that point. And in my measurement, the directivity was quite good (IMHO) all the way down to 100Hz. I believe this is because the dipole radiation reduced the output to the side.

Basically, I'm trying to determine what the downsides are to a setup like this. "Theory" says that it shouldn't work (because of the dipole peak) but it seems to work just fine.

Thoughts?

The original design: https://www.diyaudio.com/community/...d-directivity-loudspeaker.347025/post-6026915

SOLD

Hi, this is a pair of LC Audio End Millenium amp modules, unopened. (Photos of contents are from another module.) Info here:

http://www.octave-electronics.com/lcaudio/temil.shtml
https://audiocircuit.dk/downloads/lcaudio/LCAudio-TheEndMillennium-pwr-sm.pdf

Apparently can run on supply voltages as low as +/- 10 V.

These have been sitting on a shelf since... well, since the turn of the millenium, so it might be a good idea to check/replace the two electrolytics.

AUD175 (PayID/EFT), EUR120 (SEPA or Wise), USD126 (Wise) or USD135 (Paypal) including postage to respective location. Please enquire for other locations.

Thanks for looking, let me know if any questions 🙂

Yesterday I did a lame try in my old Schade/mosfet thread, to marry Zenductor and Schadeode to get a 2-stage Zenductor that solves the problem with low senistivity and low Zin. Had my thinking cap on overnight and got the idea to simplify the one I came up with yesterday. Probably this needs fine tuning, but it looks promising. Due to distorsion cancellation the even harmonics are lowered but the spectrum still is nicely falling. Just did temp simulationsand they seemed OK.
Must build a prototype using the Hammond 193 I have.

Hi,
I am looking for stand alone module amp which can receive on input signal from another DAC. Do you have positive experience wih JustBoom amp?

Is there better solution (amp only module without DAC)?

What power source do you use for JustBoom amp? Do I need linear PS or switching is ok?

Well I had a chance to listen and open covers of few amps.. the two that seem most different in design and sound seemed to me yamaha m series.. and adcom 5500 ,5800.

Sound wise 5800 was no doubt a sweet beautiful sounding amplifier. My friend is using it. Under the cover.. huge transformer. Few resistors and capacitors.

Currently I use yamaha mx1. I think it's their best in M series. Well under the cover a rather complex HCA circuitry..maybe it's very simple to some)

Sound wise 5800 tends to be very mellow sweet. Piano especially. I was overwhelmed with bass of this amp.
Kind of dissapointed with lack of high and mid range resolution...

Yamaha mx1 on the other hand not a super sweet sounding amp. Yet not harsh or brittle. Very accurate. Reveals a lot more detail. Higher resolution amp. One thing that really sets it apart from older m80,m85, mx1000 is that expensive splash of trembles. Hard to explain. Many call them airy highs.

And of course sound is very personal) my friend loves adcom 5800. Jazz, launge music truly sounds beautiful.

I prefered yamaha mx1 because of its crispness, speed, presence of dc protection, and the fact that it's really hard to get it higher than room temperature. Ice cold)
And of course the splashing trebles.. I haven't heard amps That produce similar highs.

We have used same speakers, source, pre amp of course when comparing.

Most adcom owners I know hate yamaha m line)

I am a hobbeist.. can recap amps. Check leaking transistors. But that's it. Know nothing of circuitry and current flow in an amplifier. Exploring the basics of world inside the box.) Reading few into articles

Hi, I used the 2SC2632 in my black SU-V8. These parts are well gone, and though they appear on sites like yahoo auctions, the shipping is high, and then its not known if they are real or hot, though some looked really like the old parts My silver SU-V8 is now in need of replacements.

Following a bit of search around DIYAudio forums, i came up with 2 possible replacements. I can only get D version in the KSC series, frequency is the same not the Hfe

KSA1381ESTU
https://au.mouser.com/datasheet/2/308/1/KSA1381_D-1810601.pdf

KSC3503DSTU
however the matching pair is D spec not E (which appears to be discontinued)
https://www.onsemi.com/pdf/datasheet/ksc3503-d.pdf
So that concerns me re the specs, though both have good frequency like the old

I got another pair of transitors also
2N5551 PBFREE/ 2N5401 PBFREE
https://my.centralsemi.com/datasheets/2N5550_2N5551.PDF
https://au.mouser.com/datasheet/2/68/2n5400_5401-1518545.pdf

Old parts
https://alltransistors.com/adv/pdfview.php?doc=2sc2632.pdf&dire=_panasonic

Thanks
Sam
I have the above from my order from Mouser, just not sure which is best

@Iomis Hi Cosmin, its Sam, you may remember me, i think you said you had a Technics SU-V8, did you need to change your transistors, ones above i have from my order

​

Hey!

On my quest to escape the perils of dead sounding boxes filling the shelves of every hifi store, a long search for affordable efficient speakers ensued. Recently I have stumbled upon a set mentioned above (fostex recommended design) on a Swedish marketplace, which I'm enjoying quite a bit. Being a complete newbie in this company of real? sound, I am trying to learn about how to get the most out of them.

Currently I am driving them with a Vista Audio Spark 2, which is small & simple 20w class AB amp based on a LM3866 from TI's Overture Series. They are connected with 5m (15ft) of 16 AWG Belden 9497 (the twisted orange/black) tinned copper wire. They are playing in a roughly 30 sqm room. Still experimenting with short- and long-wall positions. They sound neater out in the room, but better balanced with boundry reinforcment, so they sit now along the wall (almost in corners). I'm finding dead forward or extreme toe-in work best.

I have not yet looked inside the cabinets to see if any damping has been used, but in short I'm loving the lively, open and pinpoint presentation. What I would like to try and improve:
-more weight in the low bass 50-100hz
-some voices and instruments have a slight "horn" quality (like coming from the top of the throat instead of chest)
-sometimes slightly too forward in the upper mid-range, makes violins and trumpets for instance scream over the rest a bit too strongly

Having done what I can (I think) to optimize placement I'm looking to equipment next. From my homework on this forum and some other places I have learned that they love to see high output resistance from the amp / low damping factor. I have emailed Vista Audio to get more specs, but currently have no idea what this amp is doing to the speakers in absolute terms. Jives well with my Soundartist LS3/5A in the near/midfield. Tonally very pleasant.

So now looking forward to experimenting with amps. Some recommendations I have gathered from internets (again, mostly here):

• small/affordable SE triode amp (smooth mids and highs, but what about bass weight?)
• small/affordable class A FET amp, like Pass ACA (like above but stronger bass, true?)
• Tripath amp, bit of a wild card for me, as I've just learned abut this tech a few weeks ago) TA2024 seems to be the smoothest but also lacking in bass (hearsay)
• what else? class D?

Obviously looking for reasonable pairing, so no 5k amps at this point, unfortunately. Also, looking only at finished products or kits. I would also like the opinion on the Belden wire. Its skinny and long, not sure if this is a + with this pairing or a -.

Any input on this matter greatly appreciated and I'm looking forward to learning more from you guys and gals!

Aleksander, Stockholm

SOLD!

Selling one Soekris 1121-01 DAC-module.

http://www.soekris.dk/dam1121.html

Including a USB to RS232 converter for loading firmware and filters.

Payment through Paypal.

Price 150€

I've acquired this box & I'm struggling to find any info. From what I can't tell it may possibly be the worst design in the world.
It's a passive bandpass sub with equal sized chambers. One of the drivers is directly opposite the port, negating any low-pass effect. There is an inductor on each input which seems ineffective.

Should I bin this thing?

Hi,

I was messing about with my ICEpower 200AS2 amp, figuring out how to make mute and standby functions work. I successfully made the amp mute and moved the control aux voltage wire (DVDD-wire) to test the standby function. in this move I accidentally touched the aux-GND with DVDD-wire, causing a short and instantly cutting of the amp. I can't get the amp to react to anything now and I can't find any burnt components, but I can hear an on/off hissing sound from the PS part of the board. Can anybody help with explaining to me what might've be up with my amp?

I know I should have disconnected the power when moving the wires, but sometimes I get caught up in the enjoyment.

Link to the amp if datasheet is needed: https://icepoweraudio.com/buy/as-series/200as2/

Thanks in advance!

Nos

14 pieces 4p1l (1978/1979)
10 pieces 6n6p
2 matched pairs 6n6p
13 pieces 6ax4gtb
2 pieces 6p21s

220€ plus shipping from greece

I've been lurking for a while. THANK YOU to those who make this forum available and to those who manage and monitor it.

I have been interested in high quality audio since I bought my first stereo system back in the mid-70s. That consisted of a pair of Acoustic Research AR-5s, Pioneer separates, a Thorens TD125AB MkII turntable, and some now forgotten cassette deck. I became interested in loudspeaker design at that time, but never did anything other than read some of Thiele's papers.

A few years ago, I found a pair of Cerwin Vega AT-15s that had been abandoned. The speakers still work very well, but the cabinets need to be replaced. I hope to do that this year while also improving the performance of the speakers.

My current system consists of a laptop running Foobar that is feeding WAV files to a DAC that is connected to a Harman Kardon HK 670 Twin receiver and is driving the AT-15s.

I hope to learn much from the more experienced members of this forum.

Hi, my name is Tom and live in Webster NY, Go Bills! I've been doing DIY speakers for a few years now, I'm a GR Research fanboy and build a few of Danny's designs. X-Statiks, X-voce, XLS encores, Open baffle servo subs, etc. I saw a few videos on Gabster's channel and want to build an IanCanada DAC/streamer and found this site. I'm quite handy and have a pretty well equipt shop. I've built a couple of dozen acoustic guitars and ukuleles.

Hello everyone! I bought an mystery Eico ST 70 from ebay. Was missing an output tube and was all original. I checked all the tubes and ended up replacing all of the output tubes. Over the next few weeks I did a (what I believe and hope) to be a very nice recap job, took many photos and worked slowly and even checked as a I went along with the schematic. Anyhow, tonight I brought it up on the variac, little by little and sure enough the draw was rising and rising and pop, 3 amp fuse gone. So being a novice I referenced my instruction manual and see that if I blows the fuse with and without the rectifier in (which I tested this and statement is true) then it has to be a short in the line cord, in the two aux AC jacks, in the primary or high voltage secondary windings of the main transformer, internal or external.

Okay, deep breath, so would the best thing to do is to remove the main transformer, or just separate it from the rest of the device and slowly apply voltage and see if it starts to pull amps again?

Thank you all in advance!

We lost the heat and hot water all in one go the other night, an big ouch, oil tank took on water, snow/freeze/thaw/rain cycles of late, took out the furnice burner fuel pump. upon inspection they condemned the tank they installed in 2002, over twenty years old, telling me know that the tank mfg made some bad models in the year they sold me mine, won't deliver fuel anymore unless I change the tank that still has ~25% left in it, fun wow, now what? tech told me I could put burn diesel to get us through winter if i need too. but need to replace tank as a minimum. So now what? decision time, ditch the oil, go with what? propane, electric heat pump? New furnice? Nothing wrong with the old burning furnice now that it has a new fuel pump.

We will replace the oil burning hot water heater, installed in 2002 and change over to electricity asap.
I saw on US PBS "this old house"installion of a new Reem Hi-eff electric hot water unit with wi-fi 🙂 anyone have any experiences? I see them for sale at HDepot for >$2K CDN vs a regular equal volume unit for ~$600.00

We have no natural gas in my rural area. Lots of dead ash trees, cost the township/tax payer $1M+ plus for the last few year to take down, or get sued for damages 🙂
Now we're in Canda so what is done outside of Canada may not apply to us.

So my drivers arrived (8 Dayton 12” DVC subs) and I’d like to start making saw dust next weekend but I just want to finalize some questions to make sure I’m on the right path here

The depth of the slot?……..so the distance from the front of the slot to the rear…..that’s a 1/4 wave acoustic low pass function, yes? A 13” slot will produce a high cut starting at 250hz give or take? Is there a rough idea of the slope?…….is/can the slope be acoustically changed with some other physical criteria?……the volume of the slot?….the shape/dimensions of the slot?……the shape of the outlet?

Have I read/understood this correctly…..the area of the slot exit should be roughly 1/3 the SD of the driver? If so, what is the basis for this?……what performance criteria is determined…..do the TS parameters of the driver play a role here in optimizing the slot area?

Would lining the slot with absorbing material such as felt serve a purpose?

Thanks for reading!

I've been some three way hifi systems already but this is my first foray into full range. I designed this box for a 4" Dayton full range driver. I just print it with my QIDI printer. It gets ridiculously loud for how small it is. As far as I can tell the horn is in phase with the driver. Maybe a tiny bit off but its inaudible.

Anyways, roast away or send congrats. I just thought I would share. Not too bad for $15 worth of driver and $15 worth of filament.

I am building a new, large one, that utilizes a Tang W4 full range.

I need to replace the toasted speaker output jack on my Crate BV-60H Blue Voodoo guitar amp. It seems odd that it would short out the output transformer when nothing is plugged in. Probably why the contacts are toasted. (From the previous owner.) I would think that accidently powering the amp up with no-load, (open circuit), for a moment or two, would be better than shorting the output transformer.

Then again, I don't want to 2nd-guess the design engineers. Before I order the replacement part, does this seem like a good idea? Any harm if I install a non-shorting output jack?

Thanks all, for any info.

Artie

Hi all!

I have been holding on to a pair of rare vaccum tubes for quite some time now... but I never got the time or money to put them into use.

I've stumbled upon a website selling same brand and models for high prices and if I get to use them I'll never be able to replace one/both then they wear out.

part from ebay, does anyone know were to list these toys ?
I have tested them both and they have about the same characteristics (even tho they are marked as 311T and 311CT) they were branded/used as a pair when I got them in a old vintage equipment, retired obviously due to age and not being practical.

if anyone is interested on those, please let me know and we can sort out a test setup if needed.

I need to turn money around to cover expenses on electrical and roof work on my house. later on I might be able to get a 300B amp or some KT88 in memory of this ones that I can't really put to use

The amp market seems to be lower-powered inexpensive stuff, or >$1000 for just two channels of big power. Why haven't advancements delivered say 5x100 for $600 or something?

And in a vaguely related question, why are the inexpensive ones not so clean? I mean something like the Aiyima A07 which at Audio Science Review measures as dumping a fair bit of power, but not too amazing for distortion and noise. If you don't need a lot of power, why isn't there a really clean inexpensive amp? Is it a limitation of the amp chips? The power supplies just aren't good enough?

[cue Jethro Tull "Wond'ring Aloud"😉

I wanted to post some materials and things from high powered rocketry that might be used in loudspeaker construction and design. Thought maybe we could get some cross-mojonation going here.

Nose cones. These come in many sizes and shapes. They go from 1/2” to 7 1/2” even larger if you have the $. Most are pointy ogive or round parabolic. The pointy ones could be used for tweeter and midrange enclosures, or used on the backs of woofer magnets. Some could be used for diffraction/phase cones on full ranges. They are made from all kinds of materials, most are polystyrene plastic, but there are nosecones made from balsa, maple, hard urethane, fiberglass, and carbon fiber.



Tubes. Airframe tubes make the airframe of a rocket and are also found in many sizes and materials. They can be used for vents, t-lines, enclosures, or even stands and feet. The most common material is cardboard but they are made in hard phenolic paper, fiberglass, and super sexy carbon fiber. the high power tubes are what you want. They are thicker and much stronger than the Estes tubes. I’ve used LOC 54mm (2”) tubes for vents. These tubes are made to very precise diameters and have bulkheads and rings that you can add to create enclosures. Many of the sizes fit directly into tubes of larger diameter, for example four 1” tubes fit in a 2” tube, four 2” tubes fit in a 4” tube. Maybe doing this could make a non turbulent vent? The cardboard tubes can be fiberglassed to create a much stiffer tube. They can be veneered. The fiberglass and carbon fiber tubes are much stronger, way lighter, and a lot more expensive than PVC pipe. The tubes can be cut lengthwise and used on the cabinet edges to decrease diffraction effects.

Yesterday, workmen jackhammered a section of my neighbor's driveway. I could feel the ground and house shaking.

By comparison, a bass drum reproduced through my Maggies does not shake anything. However, it does have an obvious pitch which is something that the jackhammer lacks. 😉

BTW, I have heard sound reinforcement systems produce more punch than the jackhammer. I think we need to turn off the amplifiers. 😉
Ed

Obbligato 47u 500V PSU Capacitor

I bought too many of these for my needs, so I am selling some of them.

With a DF=0.00015 they beat and low ESR capacitor in the market.

Each capacitor has a SN that can be used to register them online and verify their authenticity.
https://www.hificollective.co.uk/components/obbligato_psu.html
Hifi-Collective sells them at £26.40/each (33 US $).
I sell them for $24/piece or $45/2 pieces, USA shipping included.

Which Audio Technology driver is ideal to replace the Dynaudio D-76/AF?

Thanks 🙏

Given the desirability of power tube distortion in guitar amplifiers and the somewhat unpleasant volume levels that it may be associated with in domestic settings, load boxes and similar things are attractive. Given that they most often do not match the impedance (reactive load) of a real spear, results can be mixed. Some amps come with their own power-soak features and oftentimes these seem to be like a built-in load-box (some amount of the output gets shed to ground through a resistor).
There are also modifications that go deeper and into the amp and reduce the actual output power of the power section but I wasn't able to find much information on how these work in general. (See https://londonpower.com/about-power-scaling-kits/)
How would one modify a standard PP power section to either implement a switch that reduces the output power by a high degree (say -40 dB). Or even better: make the reduction adjustable with a potentiometer - sort of like a master-volume that controls the output of the power section instead of one that attenuates the input that goes to the power section. Does it just come down to adjusting plate-voltate and bias to produce less output swing?

Cheers,
Lars

SOLD
NAD M51 DAC Master Series . This Digital Analog Converter is in immaculate condition. Works perfectly, no scratches, scuffs or other blemishes. Perfect condition. Remote is also perfect. Both function as new. The NAD M51DAC can amplify the signal past unity gain. (>input signal) acts similar to how a preamp works. (this is NOT a preamp per say) Superior sound , clear, crisp, vocals and instruments. Very nice DAC. Will be shipped double boxed, I do not have the original box, but the contoured foam shipping blocks are original. Packed with the utmost care. $550 Paypal Shipping included in the price. CONUS only. (48 states)

It is finally time to start another speaker build, this time I hope to get what I am missing with my current speakers. My current speakers are 2-way with Morel CAW638 and Morel CAT408 in MTM setup in a vented cabinet. Not 100% sure about the crossover, got help from a friendly Canadian here on the forum many years ago.



They sound good, but they don't have the headroom, dynamics, and capability to make it feel like a live gig. At more modest levels they are great though. Now I want a 3-way build with plenty of headroom 20hz-20kHz.

Over the years I have accumulated some parts for this upcoming build. About five years ago, when I bought my house, I found a pair of unused CSS SDX12 for a good price. I think I paid around 300 euros for the pair.

I had planned on using the Beyma TPL150 and maybe the 12p80nd but they are very pricey drivers and I've heard that the TPL150 maybe isn't always as good as some people say. Especially not paired with a 12" driver. A little while ago I got a good deal on a pair of Faital Pro HF108r and STH100 horns. The horns were unused and drivers were used but not much. Paid around 40% of what they would cost new.



Now I need a driver for the midrange. Since I have the SDX12 I don't need the midrange driver to go very low. I guess crossover could be in the 100-150Hz region, or maybe even higher? I have been looking at 10" drivers for the midrange to get better high frequency capabilites and less beaming. These speakers will be used in a living room, not for live gigs or parties, so a 10" will be loud enough and I guess I should also get enough midrange punch and "feel". I have been looking at the Faital Pro 10PR410 driver. It has low mms, strong motor, and seems to play well up to ~2kHz. It is limited in bass output but the SDX12 should be able to take care of that.

For the cabinets I was thinking of building two separate cabinets stacked on top of eachother. One big box for all three drivers would be a very heavy unit and hard to move if needed. The drivers alone would weigh nearly 30kg/speaker. The SDX12 is made for small cabinets, especially when sealed, and that's what I am planning to go for. Vented would give me more bass output but it would be harder to build (long port!) and I don't think I would need that extra bass anyways. I have a relatively small living room/house and I will have DSP and plenty of amplifier power available. The 10-12" PA midrange drivers are also happy in small sealed cabinets so that is also positive. My thoughts are to build the upper mid/high cabinet with around 10-12 liters of internal volume and the same width that the SDX12 box will need. Something similar to what Jbucap here on the forum built, but of course wider than his.



Then I build the SDX12 box as narrow as possible and adjust height to get the horn in the upper box at ear level. Then I use the depth of the box to set the volume to something reasonable. I have done a little research on sealed box size and qtc and it seems like there's nothing to worry about as long as I stay below ~0.7? DSP will be used and from what I can see in WinISD a larger box will be slightly more efficient below 30Hz compared to a 30 liter box which is suggested by CSS. I will build with 22mm MDF that I bought for 90% off when a local hardware store closed a few years ago. Will of course brace properly and use double baffles for a total thickness of 44mm.

I have been thinking a lot about whether I should go with a traditional passive crossover between the mid and cd or if I should go active. With a passive crossover I can keep my MiniDSP SHD (only four output channels) and I would only need one amplifier for the mid+cd. Downside is that I have no experience designing passive crossovers and from what I understand making a digital active crossover is easier and more flexible. MiniDSP has the Flex Eight which would be perfect for an active 3-way speaker like this. With it I can experiment and adjust with different crossover settings between all three drivers and also easily adjust volume and time delay. Downside is that I would need more amplifiers.

Right now I have a pair of Emotiva UPA-1 monoblocks but I don't know if they would be suitable for this project. They have an audible humming noise in the background with my current speakers and I assume that would be maybe even worse with a high efficiency speaker like the one I'm planning to build. Class D amplifiers have gotten better and cheaper and the Topping PA5 for example is praised for its sound and "silence" but it also has increased distortion in the higher frequencies so maybe it's only suitable for the midrange and not for the compression driver? What amplifier should I look for with the compression driver? For the subs I just purchased a used Behringer NX6000D for a very good price so that is sorted already.

I realise this is pretty much a 2-way speaker with a subwoofer used as a stand, but it's a 3-way system so I don't really know I should call it, hence the title of this thread.

Do you have any other recommendations for midrange drivers? Any recommendations for crossover frequencies to begin experimenting with?

Hello,
I just saw a thread about the Beveridges.
I have a very large roll of metallic mylar on both sides made at the time on request by Du Pont for the Beveridge importer in France.
I've had this roll for many years, so perhaps it might be of interest to someone. I don't know the quantity, but I'd say at least 1 kilometer, since it's 6 microns thick.
I have no idea how much it costs.
I can take photos if desired.
I live in France.

Best regards.

Vincent

Hello everyone. I have a beautiful 3 way single cab. Its loanly without the other drivers, we need a PW12A....PM6....PT3....and the network divider. Possibly over 50/60 years apart, these Pioneer/Fukuin Electrics components must be acquired. Singing together in harmony. I can show pictures of cab both inside and outside. Driver's are pristine condition fully working.

Hi Guys,

Recently picked up a Marantz SR5007 Receiver and it was working fine but I reached behind to plug in a network cable while it was on and knocked the HDMI monitor cable, the display dropped in and out a few times then dropped out completely. Since then there is no sound or video from any input or output.

I have found a poor-quality service manual online and done a lot of troubleshooting, its more than likely a problem component on the HDMI board which drives the whole unit but these are almost impossible to find and I am hopeful that its repairable.

Voltage supply is OK, voltage supply to and from the HDMI ports are OK, the analogue inputs seems responsive (input device detects being plugged in) but nothing comes out of the unit. Even resetting the microprocessor or running in service debug offers no clues. Its otherwise operating normally, powers on, front screen works, web interface works, just no output on any interface including pre-outs.

Its fast becoming a more advanced problem than I am probably capable of fixing by having to diagnose microcircuitry but I am hoping that someone may have experienced something similar and I’m missing something simple or may have access to a higher res service manual?

any suggestions welcome

I have seen panel meters for my tube tester on google, but for some reason, I can no longer find them. anyone?


Other info printed on meter: B&K MFG CO.. Dixson Inc. ME-12
I am no longer able to zero my meter as it never falls back to zero. always 1/2" above or below. impossible! must be broken beyond repair, so looking for a replacement.
thanks,
Walt

I am a big fan of DIYaudio. I haven't posted in a long time but have been a long time reader and consumer of all of the excellent information on this site. I wanted to pass along my latest project because of its cost and utility. I have several MiniDSP units; one for experimentation - MiniDSP 2x4 and a 2x4HD for this project. I have leaned into digital systems that provide crossovers, EQ and digital inputs at this point of my audio adventure.

My living room is not that large - 13' x 13' - so I was looking for something with a small footprint.

The system consists of the MiniDSP 2x4HD - $250;
Fosi 50 watt per channel - $50
Fosi 70 watt per channel - $55 (Amazon prime days price)
small bluetooth connector - $23.
Each speaker consists of 6 CES VW-8820D 8" DVC Woofer 8+8 Ohm - $15 each
and a full range TangBand - W5-2143 - $50 (purchased from Parts Express some time ago)

I was looking for a challenge so I decided to build the slot loaded open baffle woofer section (nod to XRK for his excellent write up). The SLOB ran out of gas around 370 hz so I used that as my crossover point.

I know there are some purists here (I have 67 year old ears) but if you have a measuring mic and digital EQ, it's pretty easy to dial in a system to your tastes.

Is it a great system overall? No, but it's a surprisely good for not much money. At the risk of offending some folks, I believe that digital EQ and multiple amps are the future of audio (my opinion), My larger system is an open baffle configuration with a Behringer DCX2496, DAC pre-amp with digital inputs and several pro amps.

This was quite shocking actual, opened a well known manufacturer's speaker and found questable workmanship. I set off to repaint this center mtm and removed the baffle/divers, which only required a few minutes. One other reason I opened it there was low pitch vibration with a gentle hand/palm hit test.
The following was shocking, when I removed a mid woofer, the large heavy "bell" was loose and popped off, with the add-on double magnet stuck to it. The glue they used did not hold at all on the back of the speaker-basket and only slightly on add-on magnet. The bell-crown was only glued at the crown, no rubber gasket around the bottom edge.

Fixes:
J weld the magnet back on the speaker
Add construction adhesive to the rear on the double magnet
Window foam insulation to remove the ringing

I will never buy another speaker from this company. It was engineered and assembled intelligently, everything but the last step!

note second pic, no adhesive on the wide surface, only a dap at the center.

I acquired a pair of old subwoofers, MB Quart model QM340CX, size 10 inches. I'm deciding what type of cabinet to make. Having looked at old car audio magazines, because the subs are quite old, I found that in the past they used to install the sub in a suspended way (or maybe called an infinite baffle?), that is, attach it to the underside of the rear speaker panel without using the cabinets. Because the subs I got were designed and made in that era, should I install them that way? (I think the subs at that time were probably designed to be mounted on the rear deck/ infinite baffle style) How does the sound of a suspended system compare to a closed cabinet? Please give me some advice.
P.S. Here are their parameters. I tried putting them in the cabinet design program (BassBox 6 Pro) but there was no infinite baffle option available.
Impedanz 4 Ohm
Re 3.4 Ohm
fs 44.2 Hz
Qms 8.51
Qes 0.77
Qts 0.71
Le 0.89
Vas 55.8 Liter

Hello humans, I'm fairly new to this fascinating hobby, a few weeks or so. I have a set of Wharfedale Mach 5 speakers which I found far to bright, especially that mid driver. So I'm looking into bi-amping them since they already have banana plugs in the back. It looks like I can just feed the woofer directly and use the crossover network for the mid and tweeter. Just by moving the red and black wires from the circuit protection board to my woofer driver. My setup is laptop to amplifier (Onkyo HT-R380) via hdmi. I plan to use software for active crossovers. Thoughts? Im looking for holes in this theory, so poke away.

Hi all,

I've been meaning to start this thread for a long while - as a forum for learning, and documentation of my own work over the past several years to design and create a very good field coil loudspeaker.

A little about me first, and some history on my project. In college I studied drawing and sculpture, and eventually graduated in visual design. For 20+ years since I've worked as a software developer. I've never enjoyed engineering other than as a means to an end. I don't enjoy mathematics at all. I know little (however, no longer nothing) of the actual physics behind a good sounding speaker.

To stand any chance in this, my philosophy has been just as it was when I entered software with a fine art background and no CS degree. I've hoped that with just creativity, a passion for craftsmanship and an understanding of a handful of very basic technical concepts... it is in fact possible to come up with something wonderful. I hope that speaks to some of you, too. We'll see.

A few of my basic design principles were these:

• the motor should perform well on 12VDC
• the motor must not overheat, and must be as strong as possible
• the moving mass must be as light and stiff as possible
• the suspension must be as soft as possible
• the driver response must be acceptably full range
• there is some opportunity to innovate upon spider designs

I started daydreaming about this about 5 years ago, and a year later had started posting work occasionally over here. I owe a huge debt of gratitude to Stefan and many others who contributed to that thread for my own basic knowledge of drivers and of design considerations around field coils specifically.

I copied one of Stefan's early designs for my own first motors, 8 Ohms and about 1.5T in the gap. 18AWG wire, about 1475 winds, high performance epoxy between each layer.

This is the point where many of you may drop off this thread - it was very costly to make them - about $1600 for a local company to mill out the steel and $180 for the copper wire. It was worth it to me at the time, though - I used that first pair for years to produce prototypes and test ideas. Endless experimenting. Lots of failures, and a few big successes. In short, worth every penny.

50 or more handmade cones and half a dozen spiders and surrounds later, this was the first driver that sounded quite good...

Basket:



Spider:



Ready to trim waste material:



Playing a song for the first time:

http://kensonger.com/drivers_v1.html

As impressive as they sounded in person, they had a few fatal flaws. The 8 Ohm motor got too hot after a few hours of use. Nothing dangerous of course, but with a 1mm gap and a washi paper former it didn't seem wise to expect that rubbing or deformation of the voice coil wouldn't occur eventually with years of hard use. The wooden frame was cool looking imho, but not durable or structurally rigid enough. The surrounds were laughably over-large. And, the silk spider was magnificent initially but eventually wore down and began to sag after a couple hundred hours of use.

Encouraged by the progress however, I decided to sink most of my annual bonus that year into designing and milling four sets of an improved motor design - still expensive, but significantly cheaper per unit. In FEMM, that design looked like this:



Minor tweaks after that screenshot got me up to a little over 1.6T in the gap. Not too bad. I had the first aluminum and brass frame design parts water-jet cut (which was pretty affordable really). Here was the metal on the happy day it had all arrived:



Alright, that seems like a pretty good start. If anyone is curious about something specific please feel free to ask - and, if this kind of chronology isn't interesting or educational to follow please do let me know - I'm happy to shift toward what is of interest and most useful. More soon.

George has received another supply of boards. SPP, SSE and SE.

No association etc. etc.

Get them while you can folks.

Some of you might have looked at the pictures I posted of a gassy 368A tube. Well I did a bit of experimenting with it's bigger brother the 388A. These are really odd UHF tubes and the 388 filament requires 1.5 volts at nearly 10 amps! To power it I used a variac and a normal filament transformer. With a 400 volt supply and a 6.5K Hammond 1629SE I was able to get close to a half watt just by driving it with with the 15 volt output from my distortion analyzer. However my observations don't follow the plate curves. At 400 volts on the plate and the grid at 0 volts it should be drawing something like 140mA. With those voltages I am seeing 65mA. I don't have any serious plans but sometimes it's fun to play with oddball tubes. It seems like a good candidate for running A2 as the grid is rated for 20mA and the plate is somehow rated for 50 watts.

I am looking to buy some VRDN boards and CapMX (single rail) PSU boards.

I am located in Houston, TX.

Facing a problem in ltspice.
When i try to increase power limit of an amp in ltspice for example +-35 to +-50 the out bias current and dc offset reduces. Is that normal? Instead of dc offset and bias should increase when power is increased.

Amp

I have for sale few unpopulated Peranders Sjöström DC Blocker DCT03 pcbs, selling at 17,50€ per piece, shipping, costs and risks on buyer's end, located in Italy, thanks for looking

Hi, are 2SC2229 / 2SA949 good in audio , for pre drivers / drivers or Vas ?. on low rails like +-35v , better use BD139/140 for higher power?.
- Bruno.

Hi, I recently purchased an audiolab 8200 CD, it works just fine. However, the led front panel is dim and hard to see unless I up close. So I am wondering if anyone familiar with this issue and what can I do to replace it.

By the way, the CD player doesn't come with a remote so I am also looking for a remote that I can buy on Amazon that works with it, assuming I can't find an audiolab remote.

Thanks in advance.