Hello guys! I’m having a pair of vintage Saba qx30k that I like very much ,for close listening ,paired with an Cyrus one and I was thinking , being that old should I rebuild the crossover? Also I have little idea on crossover design and you migh tell me what parts do I need.thank you!

I have an analog Behringer ECM 8000 and digital miniDSP UMIK-2 measurement mike I no longer need.

The Behringer analog ECM 8000 has an XLR output and connects to a standard mike input with phantom power on your measurement soundcard. € 25 plus shipping.

The digital miniDSP UMIK-2 has a USB-interface and connects directly to your PC or laptop.
Supported by miniDSP with or without Dirac, and most measurement programs like REW and ARTA. € 100 plus shipping.

Contact me for a binding shipping estimate. Original box no longer available but I will pack careful and safe.

Edit: both sold.

Jan

Hello all. I've been quiet for a while- workshop is in the middle of a very slow remodel, and most of my gear is buried. Taking that time to plan some projects, and get parts together until I can clear off a workspace to get back to multiple in-progress PCB work (the 6v6 Salas boards, my PSU boards, among others) and resume hobby stuff. I also ordered some of my PSU mosfet filter PCBs, based on Millet's mosfet filter from his Engineer's amplifier.

A while back I designed a quick EL84 SE stereo PCB, and since I had a coupon from JLCPCB, I ordered a set to play with. I have some generic 5K SE output transformers, and plenty of Sovtek EL84, Surplus 6P14P, 6N1P, 6N2P, cleartop 6CG7/6FQ7, and a suitable power transformer that should give ~290-300 volts after smoothing. Easy peasy right?

Just to be clear, I will not be purchasing any additional tubes or transformers here. I am restricting those choices to parts on hand. I have a big enough stash that I will not be spending anything except on the chassis, most likely.

Here's the Schematic, the LED is in parallel with the spot for a resistor, in order to be somewhat universal, I'm likely using a bypassed resistor-



And here's some pics of the 100mm square PCB, only change is that I rounded the corners, added a capacitor across R9 for feedback compensation if needed, and ordered them in purple. The PCB allows pentode, triode, or UL connection-




Here's a multi-layer view of the 50mm square power supply PCB i have coming as well-


Transformer specs (generic black chinese units, no frequency graph)-
REHOC Inductance Value: 12H
Primary DC Resistance: 315 ohm
distance of mounting holes: 72 mm
colour: black
Material: metal
Size: 60x55x50mm
Weight: .41kg
They arrived very beat up and dented, and I received a refund, in addition to that, I got to keep them. Some work to clean up the dents and some hammertone paint to cover the imperfections should make them perfect for a prototype build. Reviews on them were found that explain them to work well within the 4-5 watt power level, and they allegedly have adequate frequency response as well.




My chosen operation point for the EL84 is 5K load, 250 volts plate to cathode, and a bypassed cathode resistor, value to be determined by the choice to run either pentode or triode. Going to likely go off the datasheet values and adjust as needed for the 6P14P/EL84 that I have on hand.


So my main debate here, is what to do for the main topology.

I am currently considering the following three options for overall circuit configuration-
-Pentode output, 6N2P input, with cathode feedback to the 6N2P
-Triode connected output, 6CG7 or 6N1P input, no global feedback
-Triode connected output, 6N2P input, with cathode feedback to the 6N2P

I really like the idea of triode with global feedback, but I also really like the idea of running a 6CG7/6FQ7 front end, with the disadvantage being I will not have much headroom for lower level sources. Since the output stage only needs like ~8 volts bias worst case, I should have no issues running the lower mu front end. I have many 6FQ7 cleartops onhand, and less 6N2P onhand. The lower power output of triode mode is no trouble, as this amplifier will be run near field with DIY speakers of reasonable efficiency. I'm not terribly fond of triode/pentode switching, so It will likely stay in whichever configuration I build it into unless there is a compelling reason to change it up later.

Any input?

Almost everything I build is pentode connected with global feedback. Rarely do I ever go for something run "wide open" so I feel like I'm cheating going for zero global feedback. Last EL84 triode build I did was push pull with global feedback as well.

Thanks for taking a look!

I have for sale 1x stereo set

Main capacitor - 2x 15.000uF
Bias set for - 75mA

Price for set 50eur + shipping
PayPal

Any thoughts on this combination please. xt1086 and Bms4550. Plan to use in two way with 15” woofer (yet to be determined)
Thanks

I'm looking to modify my beloved Braun LS200 speakers. In fact, they're nice speakers but I'm curious to know. The LS200 are 3-way system with 4 drivers including 2 twin woofers. I've played with them by unplugging other drivers and listen to a single driver. I found that the woofers not only play bass but also midrange. I, then, tried using graphic equalizer and discovered that eliminating midrange from the woofers satisfied me. I tried tweaking passive crossovers many times to suit the setting on EQ, but, none of them archived the target.

However, I have the last method. I found the schematic of B&W Matrix 3 series 2 which are 2.5-way system. It sparked an idea. Attached is the low-pass filter circuit of the B&W.



Regarding L2 (8 mH) on the B&W's schematic, I think to add a large inductor to one of the LS200's woofers, red circle in the picture.



The objective is to limit the midrange from one woofer. On the other hand, my LS200 would be converted to 3.5-way system. Anyway, I have 5.6, 6.6 and 8.2 mH inductors in my hand. I'm thinking to try them all. But, I'm not sure whether it will create any problems. Please advice if there're problems occur; such as too low impedance, distortion created, or low-pass filter modification needed, etc. If there're any, then, I will stop this project. But if it's fine, I will go on.

Although there could be strong opinions about tube vs. solid state rectification, tubes objectively have no forward voltage cutoff, which causes ringing in the resonant tank of power transformer's leakage inductance and distributed capacitance. The ringing can be snubbed with an RC snubber, but the first few oscillations will still remain. Moreover, hard cutoff of SS rectifiers at forward voltage (about 0.7 V for regular Si diodes and 0.3-0.4 V for Schottky diodes) creates broad spectrum high frequency noise that is better be avoided.

The problem is especially important with low voltages such as those needed to power DC filaments of such tubes as 26, 45, 2A3, etc. With silicon diodes, the cutoff voltage may be as high as 30-50% of the rectifier output. And it goes without saying that noise is the last thing one would want in a filament supply.

I believe I found the solution to this problem: germanium rectifiers. These have forward voltages of 0.3-0.35 V, but that's not their main advantage. Importantly, their behavior in the low voltage-low current area is similar to that of tube rectifiers. They don't have the hard forward voltage cutoff. Here is a low voltage static plot for the Russian D305 Ge rectifier that I experimentally derived. D305 is a 10 A 50 V diode.

I have designed a PCB for adding an audio output to a Flipper Zero device after verifying that an I2S interface was available through the GPIO headers. This is my first post after hearing about the forums for years.

I am a beginner to circuit design so there may be a lot to fix. Any ideas to improve the design will be appreciated.

PCB design, BOM and schematic are attached.

I bought two units of the LM3886TF chip here in Brazil for around $32.00 each.
It was very difficult to find...
I've seen several photos of original chips on this site, these mine look very much like originals, they are up to all datasheet standards.
Any thoughts on its appearance and originality?

A Crown Powerline 2 (earlier version) came to me with a shorted output and a few other smoked components, Specifically, the Q113 output was shorted, Q110 was blown apart, and R129 was burned up. I replaced Q113 and Q108 with new MJ15015 outputs, installed a 2N3906 for the 2N4125 at Q110, and replaced R129. No other components tested as faulty.

The amp powered up ok with a DBT, and also directly to the mains. However, as soon as I attached my 8 ohm dummy load, I'm seeing pretty significant oscillation in the left channel. I assume that I may be seeing the underlying cause of the original damage. I need more experience solving oscillation issues, so it looks like I have my opportunity. I've attached a portion of the schematic showing the left channel amplifier section. Any direction as to where to start would be appreciated.

This is what my surgeon is proposing for me to deal with osteoarthritis. He said that though I'm 67 my bone density is high, I'm physically very active, and that resurfacing would be better than a hip replacement. The risks of fracture and dislocation are significantly lower than with replacement, there's a much better chance of returning to full activity after the operation though revision rates are slightly higher. If it all goes pear shaped I can have a replacement anyway.

But has anyone here had a hip resurfaced? What's been your post op experience?

My first post-op report, after three weeks, after eight weeks.

I’ve picked up a CS-34D cassette deck, which came with a matching dust cover. I cannot find a single image, anywhere, of another deck with this cover. I found an advert listing it as an option, but that’s it. I’m thinking it might be worth more than the deck itself! It’s the cover lower right. Has anyone else seen one?

Thanks,

Mat

Good morning everyone ! I'm repairing a RCF ART -710A MK2 ! In the treble amplification part it uses a class D module and has IRFB4229 as final mosfet and IRS20955 as driver which I replaced with IRS20957!
Now I have this problem! When turned on everything seems to work but after a few seconds checking the waveform on the gates of the mosfets I have an inaccurate square wave of different amplitude, to then turn off as if the driver went into protection!Is it possible that between the 2 drivers I have to replace resistive values or does it require different values for example on the OCSET and VREF pins?

Hello All

Former audio enthusiast turned recent convert after reading about the BBC LS 3/5a (Yes, i've been living under a rock for 40+ years).

Curiousity got the better of me, and I dabbled around and got lucky with a pair of Tangent RS2s. The sound is impressive and the staging even more so. Downright unbelievable how good they sound for the age.

Other hobbies? Cars, AFOL (Adult fan of Lego), love geeking out on PC hardware.

Thank you for the inclusion. Hope to share and learn more!

Cheers

I'd be interested to get some thoughts and opinions about the following issue:

I bought a second-hand DIY DAC from a member here on diyAudio. The DAC was advertised here in the Swap Meet, with photos that showed an acceptable build. The seller also posted about his build in a specific thread about this DAC design here on diyAudio. Once the DAC was delivered, the box looked fine and did not show any signs of bad handling. The seller also included some tube (bought separately), which were all in one piece. There is no reason to assume that the box was treated badly during transport.

However, the DAC itself almost fell apart when I took it out of the box. Most screws were loose, and some screws already fell out. I agreed with the seller that I should open the chassis and look inside. The mains transformer was loose and was dangling freely in the chassis. Some of the electronics boards were also loose, and some parts had fallen off (for example, the crystals/oscillators from the USB/I2S board were out with bent legs). It's hard to say if this is just a matter of straightening things and tightening the screws, or if there is some serious damage done to the electronics / boards / parts (e.g., due to the dangling mains transformer).

I'd like to try and rescue this thing, because I am actually a fan of this DAC design. However, I am worried this might turn out to be a black hole.

I asked the seller about his view, and he seems to argue that the loose/lost screws are due to poor handling during transport. I can't be sure, but the box did not show any such signs, and the tubes were all intact, so my gut feeling is the handling was not the real problem.

I asked the seller for a partial refund to make up for my time to repair the DAC, and for my potential expenses for spare parts and replacements. He did not respond positively to this.

I am not quite sure where to go from here. What are your thoughts? What would you do?

Hi all
I started a little adventure: I‘ll try to make a little crossfeed „network“ according to Jan Meiers proposition… as this is a rather simple thing, I thought this could be ideal to try myself in smd.
But I‘m very unsure about what capacitors to use there? I mean, it’s caps in the very signal-path, which smd-caps are good/best to use <duck>soundwise</duck>
Thank you

Greetings All,
My first post here.
I am building the Nutube preamp kit and may have a packaging error.

I have begun the assembly of my preamp kit and on confirming the parts selection to the instruction sheet document I may have found a discrepancy.

The write up states that the jfets Q1 and Q2 are different and packaged accordingly.
However I have found that while the Q1 package contained 4, FKH35 J113 fets, the Q2 package contained 2, of FKH35 and 2, of WH44 J113 fets.

This raised a red flag for me and I would like some guidance on whether this is a packaging error or is there more detail needed on how to populate the PCB correctly?

All of their respective bias resistors checked out consistent at 149 ohms.

No response from the store at this time after asking about a week back.

Thanks for your guidance.

Hi all. Got a C Audio SR707 giving some trouble. Problem is DC offset on both channels. One measures 20mV approx and the other measures 40mV approx. Amplifier comes on but does not trigger protect. (I believe that triggers at 1v)

The PNP long tailed pairs have 2sa872 installed and not 1085s as schematic. (Not sure if this is a factory component change ). I tried changing out one of the pairs to a matched Hfe pair (sorry can't remember what transistors I used at the time ) but that made the DC offset even worse at 240mV!... So I put back the 2sa872. Checked current mirrors all fine too. Changed out the 24k resistors on both boards and no change. Not sure where else to look.

I got this QUADRAL QE120 Amplifier for service (it's a PA, mixing, ELA-/100V-device).
The manufacturer in Hannover/Germany could only provide an "operation manual pdf",
but no circuit diagram, assembly plan etc.
Can someone provide a link or lead me anywhere I can get this?

i have lowther DX4 speakers driven by 2 x 300b mono PSE amps, and sbacoustics sb34 subwoofers (sealed in same cabinet), driven by 2 x icepower 300 AS1, both through active low and high pass filters crossed at 140Hz.

They sound pretty good but i plan to add a pair of tweeters and i am looking for recommendations and advice.

I was considering these from Fountek NeoCD3.5H

I initially plan to use a basic passive high pass filter on the tweeter, (2.2mf cap + 0.15mH coil), to pass at around 10khz, i dont think this will be ideal because the Lowthers have quite a steep rise from 1.5k all the way to around 10k so this will remain, in the future i plan to modify the active filter to include a band pass for the Lowthers, with the low pass fixed at around 2k, and the high pass on the tweeter also set at 2k, (the Founteks are virtually flat all the way from 1.5k to 30k), in theory this would flatten everything nicely (i'm hoping).

The sensitivity of both drivers seem to match quite well at 96dB, so im hoping that using the passive high pass filter initially will be OK until i can get round to modifying the active filter (which has gain adjustment if necessary).

Your thoughts and advice would be welcome

Thanks

My first set of speakers. Two transmission line, well quarter wavelength, bookshelf speakers and a TL center channel. Wish some of the cut outs were better but considering I was free handing with my router I guess I'm not so bad. They sound awesome and I'm making a set of main floor standing speakers, TL speakers again, and a small set of TL floor standing speakers. Having a blast. Want to make a custom subwoofer but I already have a working budget Sony subwoofer so I guess I'll pass for the time being. What do you all think?

suitable for small gatherings and lower spl material. The cabinet is 0.83X scale of a cabinet published by BesPav for Fane's "triple cone" 12 inch fullrange speaker.

Hi All,

I've noticed that many home theatres feature beefy tower speakers, centre channels, and surround speakers (like the SVS Prime Series), capable of reaching as low as 30hz or even lower. These setups are often paired with high-output subwoofers covering the 20-100hz range.

In a theatre setting, dynamics play a crucial role. Sounds range from quiet whispers to intense explosions, gunshots, and dramatic music. It's essential to capture this range effectively.

Another point to consider is the low-performance amplifiers in most AV receivers compared to high-fidelity, two-channel amplifiers. The former typically falls short in handling low frequencies as effectively as a quality subwoofer amp or plate amp. They also struggle to drive low-efficiency tower speakers to high SPLs and don't love <8ohm loads.

Instead of hifi woofers, which sacrifice sensitivity and dynamic range for low-frequency extension, wouldn't PA-style woofers be a better fit? Furthermore, should we consider using compression drivers in short, wide directivity waveguides instead of dome tweeters on flat baffles?

I'm thinking along the lines of a combination like the SB 34CD-PK with the 6MW150D or 8MWN150 in a two or 2.5-way reflex box. You could add a midrange driver if you want to get fancy, although the specific driver isn't crucial to this discussion; it's more about the design philosophy.

The use of PA drivers could add ~6-10dB more sensitivity while not compromising bass due to the presence of a subwoofer(s).

What do you think, am I looking at this wrong?

I acquired an vintage amplifier and started the journey of giving it a new life. I have managed to repair most of the damage and have come to a working device.

But there is one problem still to solve. There is a DC offset on the output side of about 600 mV. And it's only visible when there is an input signal present. The AMP has a DC bias adjustment, and it works fine 2–5 mV on the output. I traced the problem to the preamp board; the NPN side Q412 (2SA968) is not showing this behavior. Only the PNP side Q411 (2SC2238). I have 2 of the same amplifiers; the other one has the exact same problem, but only a 200 mV DC offset. I need to mention the original Transistors on the preamp board were damaged and i needed to replace them.i checked all the parts and everything seems fine,Maybe there is a biasing problem on the PNP side, i replaced the transistor with an equal China copy. Furthermore, I really don't know. I hope someone will be able to point me in the right path for solving this technical problem.

Original source for the documentation (HARMAN KARDON HK-775 SM-2 service manual & repair info)
https://elektrotanya.com/harman_kardon_hk-775_sm-2.pdf/download.html

Original source for the documentation (2SC2238 Datasheet) https://alltransistors.com/transistor.php?transistor=12929
Original source for the documentation (2SA968 Datasheet) https://alltransistors.com/transistor.php?transistor=9123

(This is the PRE-DRIVER board.) Pink marks are all the components on the PRE-DRIVER board.




Left (The Signal at the Transistor output Q411 2SA968) PNP Side DC offset is visible
Right (The Signal at the Transistor output Q412 2SA968) NPN side has no visible DC offset.


DC voltage at the terminal output when a 1Khz sine wave signal is applied


DC voltage at the terminal output when no signal is present


Don't hesitate to ask for more info or measurements data, i will be more than happy to provide it.

Just a quick copy and note

It's been a long time and I look back wistfully, I just came across my old circuit board films... My Aleph5-mono clone - with BUZ because the IRFs were not available at the moment. My implementation from 2001, it was brewing in me for three years - and at the latest after I was allowed to listen to the original in silence and peace (probably in 1996 or 97), I realized that I loved this amp. What a fascination that was! To this day, this Aleph haunts my amplifier self in a positive way.

Hi
I'm new to this forum, so I hope I'm not breaking any rules here or am posting in the wrong place, but I'm trying to source a Powersoft Digimod 1000.

If anyone has one and is willing to sell, or.knows where I could find one, please do let me know
Thank you
Ben

First four posts copied from a much older thread,m th efirst post in this thread is #5. Moderators note

http://www.diyaudio.com/forums/showthread.php?postid=1428990#post1428990

Click to expand...

Critical content of above post. Links to posts with technique information & patterns

Here are links to all of the posts and a picture gallery of the treated drivers, dealt with in the posts. Some are virtual treatments and I will be happy to provide this for your drivers too.

Lowther DX4
https://www.diyaudio.com/community/threads/enabl-processes.100399/post-1197871 post 127/128/129
https://www.diyaudio.com/community/threads/enabl-processes.100399/post-1210730 post 158
https://www.diyaudio.com/community/threads/enabl-processes.100399/post-1209986 post 169/170
https://www.diyaudio.com/community/threads/enabl-processes.100399/post-1210730 post 184
https://www.diyaudio.com/community/threads/enabl-processes.100399/post-1212967 post 192/193
https://www.diyaudio.com/community/threads/enabl-processes.100399/post-1215579 post 207
https://www.diyaudio.com/community/threads/enabl-processes.100399/post-1227619 post 252

Fostex 127 E
http://www.diyaudio.com/forums/showthread.php?postid=1224615#post1224615 post 241
http://www.diyaudio.com/forums/showthread.php?postid=1225189#post1225189 post 247

Fostex FE126e (some also applicable to FE127e)
http://www.diyaudio.com/forums/showthread.php?postid=1466489#post1466489

Lowther PM6A
http://www.diyaudio.com/forums/showthread.php?postid=1248682#post1248682 post 345
http://www.diyaudio.com/forums/showthread.php?postid=1256080#post1256080 post 373

Hemp FR 4.5c
http://www.diyaudio.com/forums/showthread.php?postid=1264670#post1264670 post 374
http://www.diyaudio.com/forums/showthread.php?postid=1265844#post1265844 post 375
http://www.diyaudio.com/forums/showthread.php?postid=1267406#post1267406 post 382

Lowther A 45
http://www.diyaudio.com/forums/showthread.php?postid=1316103#post1316103 post 668

Hemp FR8c
http://www.diyaudio.com/forums/showthread.php?postid=1359745#post1359745 post 1039
http://www.diyaudio.com/forums/showthread.php?postid=1363694#post1363694 post 1049
http://www.diyaudio.com/forums/showthread.php?postid=1364505#post1364505 post 1060
http://www.diyaudio.com/forums/showthread.php?postid=1367676#post1367676 post 1094
http://www.diyaudio.com/forums/showthread.php?postid=1371260#post1371260 post 1107

Fostex F120A
http://www.diyaudio.com/forums/showthread.php?postid=1407368#post1407368 post 1843

Fostex F200A
http://www.diyaudio.com/forums/showthread.php?postid=1479198#post1479198

Fostex FE167e (applicable to 166/206/207 as well)
http://www.diyaudio.com/forums/showthread.php?s=&threadid=133645

Jordan JX92S
http://www.diyaudio.com/forums/showthread.php?postid=1460290#post1460290

Eminence Beta 8a
http://www.diyaudio.com/forums/showthread.php?postid=1821202#post1821202

Dayton DA 175-8
http://www.diyaudio.com/forums/showthread.php?postid=1842022#post1842022

Phase Plugs
http://www.diyaudio.com/forums/showthread.php?postid=1301905#post1301905 post 621

resonance from u tube http://youtube.com/user/shermph
http://www.diyaudio.com/forums/showthread.php?postid=1231568#post1231568 post 270

Personal reports
http://www.diyaudio.com/forums/showthread.php?postid=1269281#post1269281 post 386
http://www.diyaudio.com/forums/showthread.php?postid=1275431#post1275431 post 414
http://www.diyaudio.com/forums/showthread.php?postid=1275474#post1275474 post 417
http://www.diyaudio.com/forums/showthread.php?postid=1302282#post1302282 post 626
http://www.diyaudio.com/forums/showthread.php?postid=1317429#post1317429 post 675

Good morning!

I'm feeding on this thread (especially post #31 / #32 and wondering about the variations in the implementation...

While in the build-guide for the F4, a X rated cap is placed across the AC live and neutral, Mark Johnson seems to be in favor of a C-R network (across the switch or across AC live-neutral?)... and some explanations seem to make sense (like, no need for R if the C is small enough), I am looking for advice on how to properly, correctly install this?
Is the omission of R a compromise or just plain good (or "good enough")?

Here's the external documentations (re-uploaded, sorry, and the PDF can't be inserted):



Have a nice day!

These are "raw" High quality american walnut wood frames + 3 mm thickness aluminium top plate + perforated aluminium bottom plate.
Dimensions are:
390 mm x 450 mm x 80 mm.........3 units
260 mm x 580 mm x 80 mm.........1 units

Price per unit ......140 euro + shipping anywhere......
Thank you.
I use it on these projects:
https://www.diyaudio.com/community/threads/el34-baby-huey-amplifier.326920/post-7380662

Hi all,
I have this Computer 2.1 woofer. Would like to know how it works. The enclosure is divided in two parts, A and B. B Part (Shown in light blue color) is sealed. Speaker cone faces the A section. This A section has port which passes through B section to the listener. My question are...

1) if one wants to remove the port make a sealed woofer (speaker cone facing listener) which section volume should be considered ?

2) If one wants to make speaker cone and port both front facing how to go about it ?

thanks

Well its allot of videos... sorry. but i am trying to make a pair before the end of this week , i thought ill post it here to since some here might be able to shine a light on why some things look as they look 🙂 / measure , part 8 might be the most interesting.. with the measurements. where the weird dips are seen.



PART 1 - Making spacers, not exactly working to plan.
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PART 2 - cutting the frame. its kind of a puzzle i must add
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PART 3 - Its late so i could only do a task that does not involve making dust, so i make my first sock attempt
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PART 4 - Small tasks adding magnets etc
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Hello everyone!
I've been working on an audio project and I'm planning to use the pt2314e. I've downloaded the datasheet but I don't find the i2c commands to communicate with the MCU. Am I missing something or is there a site that provides this information?

* December 12, 1943 in West Palm Beach, Florida; † April 18, 2024 in Osprey, Florida




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I've pick up a pair of Threshold SA/12e mono blocks which will arrive next week. My plan was to listen to them for a while and then decide if they could us any sort of tune up / rebuild as they are all original from 1992. After contemplating their weight and where they will rest (not on dollies, but on shelves), I'm wondering if there are some basics I should consider before getting a friend or 2 to get them where I want them?

-Power supply caps?
-Caps on FEB?
-I remember years ago when I was tinkering with Sansui equipment, they had issues with what everyone called "Black Caps" that were prone to failures. Anything like that on these amps I'd want to address sooner rather than later?
-Any advice would be appreciated ... and might save me a trip to the Chiropractor down the line!

Happy Holidays.

Eric M.

Two ACA amps, version 1.8, using stock DIY audio store kits. I built these last year. I also installed the DIY SMPS DC filter in each of these. I have these set up as bridged mono-blocks. They sound great. $500 for the pair.

Goodmans Axiom 201. I've acquired a pair of these in near mint condition. Struggling to find a use for them.

I'm on another Car Audio forum, but I thought of getting a different feel and opinion from DIYAudio. I like reading about Car Audio and Electronics. I think just reading the article and comments helps me become a better technician. Which is the whole point of me joining a forum. And I'm from Hawai'i.

years ago I remember reading an article by someone who measured the T/S parameters of his 416b in his Altec model 19 and found the factory cabinet was much too large for optimum results. Can anyone refer me to this article? Seems that Altec actually recommend 7.5 cubic feet as the optimum for a 416b but I thought I recalled the previously mentioned article as being somewhat smaller but I am not sure of that. Any assistance would be much appreciated. I have seen reflex designs as small as 7 cu ft in volume. Any Altec owners out there who have shrunk their model 19's with success? Thanks for any input. Best regards Moray James.

Hi all,
I got this magic subwoofer with 6 x 8" elements inside it. It is equipped with 2 amplifiers inside both driving 3 elements each. I took a big risk and bought it defective but it was working at time of bying it. But hearing some noise when powering it up so decides to have a look inside. What i found was 70V dc coming from one of the amp at speaker output, so i measured all the elements coupled to this amp and luckily they looks ok (13.5ohm each).
There is some burnt components on the amp itself and a shorted output IRF4227 between S and D. It is 2 resistors and also a capacitor with signs on it. Should i also replace the driver IC IR2110s or could thisone be measured before putting a new pair of IRF4227 ?

Hi tech guys

I'm seeking some clarity on correct tuning for 416 Altec woofer (reconed by GPA) in new cabinet.

The internal volume is very close to 170 liters.

Cab is double walled and braced. Approx 80Kgs each.

The port is 300mm x 65mm x 80mm deep.

How can I check the tuning of this with the 416 T/S specs?

Altec Thiele-Small Parameters

MantaRay horn with 291 1.4 inch driver.

BTW, the speakers are sounding FANTASTIC...so this is an exercise in theory/checking only.

Cabs finished in lovely two pack poly, grey, with pearlesc additive.

Xover is 750Hz, with LR2 and quality Jantzen silver caps.

With thanks, Andrew.

The LSA Signature 80 speaker is currently in production and should be arriving in the next month or so. I am really happy with how this design turned out. As the designer, of course I think it sounds great. I voiced it for a natural presentation that has clearly resolving highs but is non fatiguing. The midrange is lush and smooth and the chat punch is all there. I figured there will probably be more questions about this speaker as it gets closer to being released for sale by LSA so I am making a dedicated thread for it to provide a forum for questions and answers.

The exterior finish is without question, one fo the best I have seen. The rosewood looks so good, it almost looks unreal. I had to put it under a microscope to see that it is indeed genuine real wood. The craftsmanship is so good, one has to wonder how the cabinet makers can do this sort of thing. I know I can’t get anything like this myself in a wood shop.



Design is 2 way ported reflex (50mm dia vent on the back) with 7in aluminum cone midbass driver and 3in planar tweeter in a custom waveguide. Crossover is at 3.5kHz and uses all high quality film caps and large gauge pure copper wire inductors with audio grade non inductive wire wound flameproof resistors.



Premium Viborg binding posts with carbon fiber accents on custom CNC aluminum plate.



Cabinet is 3/4in MDF and 1.5in thick MDF on front baffle finished in gorgeous genuine rosewood veneer expertly applied with a satin finish coat.

Measured (quasi anechoic near field) frequency response is 38Hz (-6dB) and 22kHz (-3dB). Sensitivity is about 84.5dB at 2.83vrms and 1m. Polar response is uniform within +/-2 dB over 60deg inclusive angle for a wide sweet spot. Time alignment is precise and the soundstage and imaging are superb. The XO was designed to allow an easy to drive 8ohm nominal load (probably closer to 11ohms for most of music).

Here is the predicted speaker electrical impedance:



Here is the frequency response measurement in room (my lab) on a 40in high stand) - disregard response below 150Hz due to room modes, note the measured acoustical phase response and can be seen to be very smooth through the XO region for great imaging:



Have a listen (recorded with iPhone 12 Promax):

Login to view embedded media

I am trying to find an old Fender amp website that I used quite often but now I can't remember the name of it----it had all the history and schematics, pictures, specifications, timeline of various versions, etc. Does anyone recall the site I am talking about? It wasn't an official fender.com website; it wasn't Robinette's site; it was called "Fender amp field guide" or something like that. All I have found is a couple of threads that mentioned it had gone away and then come back again.

Has anyone tried using any of the prefab 12” vented car subwoofer boxes for the Betsy-K? They usually run between 1-2 cuft. Looking for something cheap and easy for a basement system.

Hi!
I have a SVS SB16-Ultra.
When i connect it to a source the only thing thats coming out of it is a flapping sound.
Do anyone have a clue what might be the problem?

I have a pair of Edcor 50W 3.4K push-pull output transformers with 8 ohm secondaries. I believe I may have mounted one of these (I can't tell which one), but I never even cut or soldered the leads. I will sell these for $150 shipped CONUS, which is about half the price for a new pair.

I have recently acquired a dead crown drivecore amp. The two Igbt’s in the psu were exploded, legs blown off! No pcb damage luckily. Also four 10R resistors around the gates got vaporised and two diodes blown short circuit in the gate drive. The markings on the diodes GY63. Google drew a blank. Can't tell if these are Zener’s or fast recovery diodes the resistors and diodes are SMD. The switching transistors are driven through pulse transformers so hopefully no other components in the driver stage damaged. the two transistors to discharge the gates seem to measure ok with a multimeter. does anyone have a schematic of a cdi drivecore amp? i found one on YouTube but it’s rather low res and the owner of the channel want $150 for a pdf copy. I have attached the low rez copy of the relevant page. Can’t make out which are diodes or resistors.

Hello,

I have a few spare boards that I bought to offer the community. These are the F5P and M2 - both V2. Many thanks to Fran and Patrick for the design and layout of these boards. Selling for $16, plus $4 USPS shipping - in the USA only for now.

Please PM with your PayPal ID, and address if interested.

Rick

Edit: Point of clarification... This offer is for a stereo pair of each. 4 PCB in total.
Edit 2: Photo and shipping will be via USPS Ground Advantage.

Hi fellow forumers
I'm going to restore this amp for a friend of mine
this is the unit: AM-240 Ampl/Mixer Olson Radio Corporation; Akron, Ohio, buil
Obviously, the one I've in the bench is not in such a good shape, take a look:
Well, lacking the schematic the restoring job, while not impossible, becomes considerable more difficult. So If one good soul can share the circuit, it will help in an just and heroic cause.
Cheers
J.

One only: Black anodized rack mount case size 17 x 12 x 3 in.
Price $30. plus shipping and PayPal charges. Ship via Canada Post or UPS.
Sorry, unable to post a picture due to the size being too big,

I have an Ion Obelisk which as a fault where the output is lower on one side, I've checked the psu voltage to the poweramp which +60v however the voltage on the positive side of C1 is 21v on one side ( which if im reading the schematic correctly is correct) and only 9v on the other.

Any pointers on where to look?

Hello. I am in the construction of full range speakers.
I would like to try the Markaudio drivers.
Looking at the box plans that Markaudio suggests, I see that it mentions required resistance for the cables from the amplifier to the speaker and for example "high output impedance amplifiers".
I do not understand what you're referring to.
I have a Marantz PM6006. Will it be appropriate?
I ask before getting into the construction of the speaker.
Thank you

Hello, let me start with I picked up this nice condition JVC receiver because it hosts a 130w per channel amplifier. However when I start turn the volume up and I get to an almost perfect level of "loud" but not "distorting" (it's not even nearing distortion, so I can tell there is still lots of room for more volume...) but when I pump it up a bit more the over current protection kicks in. (I have about 14 other receivers here all around 100w to 110w and they all drive these same speakers much louder with more punch).
I can tell whoever set this protection circuit up must have leaned towards safety over performance, because the heatsinks are not even hot.

I opened it up and I thought I saw "temperature sensors" thermistor's near the amp chips, with the "left channel" one being bent very close to the amp IC (I bent it back like the others) and I assumed ok now I'll get more volume. But I got the same cut out at around the exact same volume. So I installed a large PC fan on the heatsink to keep it cool... and it cut off at the same volume (I might add this is not digital/display volume on the unit - but the same audible volume).

So there is something causing the cut off to cut out long before it's technical abilities are overloaded/tapped.
I'd like to figure out where the over-current protection circuit might be, and possibly remove it and or change it's value so it does not cut out so soon before the peak performance of this unit has had a chance.

I might add some key points:
The speakers I am using are in A+B combination (4 speakers) / the unit states in the manual use only 8 or 16ohm speakers at each terminal, however both pairs of my speakers being used are 4ohms. Technically speaking I get away with using these same speakers on other receivers fine (making sure to always use a good fan to keep the heatsink cool) and there is no issue driving them hard for extended periods. I have one Sony 110w which only has Speaker A terminals and it's got a hard switch to select 4ohm or 8ohm, so I set it to 4ohm and installed the 2x 4ohm speakers totalling 2ohms and ran it for 10mins, the heatsink got so hot I panicked and installed a permanent fan. Now it runs fine 2ohm speakers testing for a solid hour at loud volume, no issues (and stays just warm now).
So out of all these other receivers I've run these same speakers off - this is the only unit having "issues" and I think it's simply because they set the cut off limit too low.

I've included some images, in the one image I have two arrows, the Red Arrow points to a trimmer that is on only found on the L / R channels amp boards. Judging from the type of wires running to these pcb's I'm assuming these pot/trimmers are a "line input levels" (for gain up or down). However I'm not sure how these circuits were designed, and more importantly what an over-current circuit looks like (and or where they would locate it) so these might also be the "cut off voltage trimmers?" I dunno hence why I am posting here.

I've also included a potential "sectioned out pcb" that looks like it might be regulating the voltage... so perhaps this is the over current circuit?

But lastly, I also marked a "yellow arrow" to what I originally thought was temperature sensors doing the cut off....(it looks an awful like a Thermistor to me) AND the PCB label for this part is literally "TH731" further indicating it's "THermal" sensor, so perhaps I can just swap these out with another value? Or put a resistor in their place? But what value... hmmm.

Any help would be greatly appreciated!

Recently acquired an HK Citation11 & 12 pair from the mid 70's. I noticed a 1K resistor across 2 of the 4 caps in the PS of the HK12 that does NOT appear in any schematic nor on the parts list of the HK12. Has anyone found this in an HK12? Anyone know why HK or someone would install such a resistor?

I used this sub a few times in the early 10 - 12 years I owned it. Divorce time my ex and her friend werent very careful loading it into my pile, so no chance of selling due to chips and surface scratches. Used it in an early iteration sound system here, until I went to OB and V instead of P wave bass. Been down in the garage ever since, never hooked it up to the system there. Sooo,, rather than build a new construction -




I glued the two back pieces in place, where the rear aperture ends up vertical. Cut to save the original radius. Size is basically the ample shelf space the amp chassis needed on top. I'll probably fill the notch, as I have plenty of wood there left over.

Handle on top, some rubber feet for the bottom. Coat of paint - wish I had the paintable tolex stuff on hand - and should look fine for me. I have the round grille for the front, held in place by Velcro. Granted, it's a lot heavier than a pine board enclosure....

Got a working 12" sub driver and plate amp, if anyone's interested! ;')

Hi I am a new member of the forum, I hope i am in the correct part of the forum
I have an Allen and Heath ZED 428 analog mixer that i use for my small home recording unit
The mixer has a problem on 1 channel so its not a major problem,
if the eq button is pressed to activate the eq then the sound disappears, when i press again the sound is back
So on this channel i have no control of the eq
I have some experience of repairing various Analog audio "things"
I intend to open up the mixer and remove the channel and see if i can repair it
Any help with this would be great! (drawings ?)
Regards James

I have a bunch of 6AS7G I thinking of building with in the future.
But I wonder do they sound best I SE or P-P?
Nevermind the outputpower just the sound Quality.
Schemas are welcome..

The sound from the right channel of my Sherwood SEL-400 amp dropped out suddenly and had a "hissy" fit, no smoke but I did smell something cooking when I opened up the amp and noticed that a very faint smell seemed to come from the Right channel output transistors.

The schematic indicates that output the transistors are SJ1936 & SJ1937, these are present in the Left Channel and they each have a "blue dot".

The Right Channel has Motorola SJ1902 & Texas Instrument SJ1903 which are obviously replacements so the amp must have had this problem before.

I pulled the outputs to test them and this is what the PEAK Atlas showed. (Three of them read what is indicated with an asterik*, the fourth does not). My guess is that the Right Channel transistor Texas Instrument SJ1903 is faulty since it is the odd man out. Can someone please confirm this?

Right Channel:

Motorola SJ1902

NPN Darlington Transistor
*Diode Protection between C-E
*Resistor Shunt between B-E
*hfe not accurate due to B-E res
Current gain hfe=27
Test Current Ic=2.50mA
Base-Emitter V Vbe=0.860V
Test Current Ib=4.096mA
Leakage Current Ic=0.000mA

Texas Instrument SJ1903

PNP Darlington Transistor
Current gain hfe=34
Test Current Ic=2.50mA
Base-Emitter V Vbe=1.172V
Test Current Ib=3.785mA
Leakage Current Ic=0.000mA



Left Channel:

Motorola SJ1936

NPN Darlington Transistor
*Diode Protection between C-E
*Resistor Shunt between B-E
*hfe not accurate due to B-E res
Current gain hfe=22
Test Current Ic=2.50mA
Base-Emitter V Vbe=0.807V
Test Current Ib=4.148mA
Leakage Current Ic=0.000mA

Motorola SJ1937

PNP Darlington Transistor
*Diode Protection between C-E
*Resistor Shunt between B-E
*hfe not accurate due to B-E res
Current gain hfe=23
Test Current Ic=2.50mA
Base-Emitter V Vbe=0.841V
Test Current Ib=4.113mA
Leakage Current Ic=0.000mA

Hi diyers,
I would like to submit this project for a mid-bass transmission line to you. I kindly ask for your help in identifying any errors or improvements.
The desired result was approximately 40-500hz bandwidth and the woofer selected was the Volt RV3143.
I tried to model the line with the Hornresp SW, these are the parameters used:

• TL section: 800cm^2
• TL length: 203cm
• speaker offset: 60cm
• section filling: 60% short part, 10% long part

The only way I found to replicate the upward extension declared in the speaker graph was to "cheat" on the Le parameter, lowering it quite a bit, but maybe I did something stupid.
I attach some screenshots, and thanks in advance for any help.

Hi all,

What CAD software are you all using to design your chassis?
It's time to put this thing in the casing it deserves.
Thanks and Cheers!

Ruben

Hello, im currently planning a build and thought i would "steal" the ldvor TPS7A4700 regulator and make my own, it wasnt really rocketsience, i just looked at the BOM and at the official datasheet...

What do you think what's a useful infrasonic extension for home theatre? I loved chasing single digit extension but I'm not so sure anymore.

I had the Bag End Infrasub18 that played 8Hz. It sounded nice although only at very low levels.
I built a dual RCF LF18N405 450L ported subwoofer tuned @15hz in my hobby room. This one still puts a smile on my face when played at higher levels.

The problem is this though:

I built a dual B&C 21SW152-8 540L ported subwoofer tuned @11Hz in my living room and I also have a quad Visaton 15" TIW400 sealed subwoofer in there. I did some measurements and the sealed sub quickly drops off under 30Hz. Both ported subs also have a gap between their tuning frequency and the first room mode and I feel that both subs together fall a bit short around 20Hz without EQ. Also the movies with 10Hz content are rare.

I'm thinking of raising the port tuning of the B&C to 15Hz and also rebuild the sealed sub into a ported one also tuned at 15Hz. This way GD only starts to rise under 20Hz so music still sounds tight? The (still low) tuning frequency will also prevent the woofers from over-excursion below tuning?

Your thoughts?

Hi friends
I need your help regarding upgrading my opamps in my mark levinson 33H
All the modifications that I have made to those amps gives them a new life and the sound became more analog.

However my question is divided for 2 parts:

1. The first part since those 33H has few revisions the earliest version uses AD705 and later version uses OPA277P
I have contact Harman group and they say that instead of the AD705 they use LT1097
I have compere the specs of the OPA277P vs LT1097 and I see any reason why to use LT1097 since the OPA277P is better by all means.
Did I miss something???

2. The second question related to the oscillator board of this amp
Since this amp has an AC regenerator for the input stage.
The oscillator uses NE555N and this connected to a series 3 opamps AD712JN
I was thinking to upgrading those opamps
To an opamps that have better specs of noise rejection to have better cleaner AC
Instead of the AD712JN I saw 2 options
OPA2134
OPA1642
The 1642 has better specs and is much faster than the 2134 and I'm afraid of oscillating problems.
Since I'm not expert in electronics
Please help me to to decide what to do in this case
I'm looking for direct replacement
If you think of better opamps and more suitable please let me know
God bless you all
Thank you

Perhaps I originally posted this question in the wrong forum since I have received no replies. Yamaha receiver, RX V3000, no audio from left channel when using digital/optical input. Analog/RCA inputs work as they should, provide sound from both channels. Different digital cables give the same result. Input is set properly. Burr Brown DACs, 1704. Do these tank over time or could there be another issue? Where do I begin to trouble shoot? I have compared multimeter readings from one good identical Yamaha DSP board to the one in question, and all appears to be consistent. I am stumped. Any ideas?

How to make a tweeter measurement using software ARTA, example from 500hz? In STEPS you can set the measurement frequency, but in ARTA I couldn't find where.

Just want one board, condition is unimportant so long as the 1794 chips are good.

What is going on with the Hoffman Amps website? When I tried to access it today, I got a VERY LOUD warning that it contained a Trojan virus!! I have Norton anti-virus on my computer. Anyone else experience this?

Interested in Nilai, either stereo or monoblocks. Would pay 900 shipped for the stereo, or 1100 for the monos assuming good condition. Let me know, thanks!

Can anyone here help me by deciphering the value on this tiny device which I thought was a capacitor?
Thank you!

Hi
I've got 2 IMF, 3021 GT 03, I think they were made by Elac, woofers, used in the TL Range, they are in good condition, can provide DAT v3 data.
I used them for a while in a diy tl speaker, but decided to build a new set up, so no longer needed.
Price 125 Euro each, when bought together, total 225 Euro, shipping must be payed by buyer.
Cheers, Tom.

I clone the above in mono block. Recently the right mono block B+ shot above 1000V. As a result the tube was damaged. The B+ used be about 955V. My Left mono block is still working.
I would like to know the reasons for the B+ to shoot up. Thanks

This is a bass preamp , basically cloning a Gallien-Krueger Fusion 500 tone section . It has a 300 volt B+ feeding two 12ax7s driving active Lo-Mid , Hi-Mid , Bass and Treble controls. The power supply is one I developed from a flash-gun circuit I found online and a little 18mm flyback transformer from an old flashgun along with a 2sc4834 transistor , two polarised caps and a resistor and a couple of diodes. The 2sc4834 was chosen because it seems to have a high power-handling capability , so would be less likely to overheat , I don't know enough about transistors to make a more knowledgeable pick. For so simple a setup it performs remarkably well , I have a voltage regulator taking the 9v wall-wart input down to 6.3 volts and that feeds the heaters and the psu. I used an LD1085 regulator but it does seem to heat up more than others I have used so I would change it next time. The transformer is wound to produce 300 -odd volts from 6v battery supply in the flashgun , so with 6.3v it produces around 320 volts , I had to put a dropping resistor in . (I suspect it could go quite a bit higher if needed) . The voltage on the plates is about 202 v which is close to the G-K schematic. There's no sag I can see or hear , and the waveform of the AC ouput looks reasonable to one who knows very little about these things , the DC doesn't have a measurable ripple on my little handheld oscilloscope , but I'm new to all this and someone with better knowledge and equipment would be better placed to know if that was so. The preamp is quiet , on a frequency analyser the only sign of the switching power is a very tiny peak , mostly below -110db , which comes and goes for reasons I haven't found yet , I think it's probably emitted radiation from the transformer and I've done some shielding but perhaps it needs better. The peak and the switching is at 11kHz , which is far enough above the range of a bass guitar to not interfere , and at least to my ears there is no distortion anywhere (old ears , mind you).
The main problem with making and improving this psu is the fact that most of the flashguns I have taken apart to get more transformers use either smaller ones in the more modern versions and larger ones in the really old style. It seems that with this particular circuit the sweet spot for transformer size is around 18-20mm , to get a high enough frequency and a steady current supply. I have bumped the frequency up towards 20khz but got much more heat than I was happy with from the transistor, and above that it gets very jumpy. (I thought about winding my own and twice sent off for ferrite cores and bobbins from China , both times just got a load of broken ferrite bits in a bag with no bubble-wrap or anything to protect them.) I keep foraging them when I see a job-lot of old guns on the Bay , and one day I'll find which ones have the right size.
The circuit is minimal to say the least , it's possible that someone with more understanding could create a more sophisticated one that could utilize the more easily found smaller transformers , perhaps switching at a higher frequency. And I have learned that if there is noise , there are ways of implementing snubbers before the transformer , but they require pretty complex maths and knowledge of the transformer specs I think.
I had another valve in there at one point , another 12ax7 as an overdrive valve , and it worked fine , but the voltage regulator started to get more than a bit hot supplying the extra heater current so I took it out - I wasn't aware of the transformer having issues with the extra power however.
The resistor size depends on the inductance of the transformer and the target frequency. The multimeter resistance of the windings is about 0.5 ohms for the input winding and the flyback winding , and varies between 150ohms and 350ohms for the output HV winding on different transformers.
In the pictures the psu is crammed into a yellow box at the end , that's because the initial project was "Can I get a valve preamp into a Coleman's Mustard tin?".. the answer was "No" but the psu fitted into the lid OK.
The first frequency trace is with the bass pugged in, no sound, the second with a string plucked and the peak showing bottom right . It appears for maybe twenty seconds then disappears for a few minutes , there's no audilble change to my ears.
The controls on the preamp are : top , bypass switch and Volume control -: front , 3 way switch to alter the bypass cap on the first triode , (no bypass/10uf/ resistor and small cap.) , switch to add "Deep" to low-mid control , Hi-Mid , Low-Mid , Bass , Treble , input and output jacks.

The Clio seems like an easier system but it’s twice the price.
Which do you recommend?

LOCAL PICKUP ONLY. NO EXCEPTIONS. Costa Mesa, CA

I have a pair of what appear to be 4 Ohm Apogee Scintillas that are in need of full restoration. My goal here was to follow in AVWERK's footsteps and make this a fun DIY project. I just don't have the time.

I have the following:

1. Pair of beat up Scintillas. They were stored outside by previous owner, they will need full disassembly, cleaning, probably new wood just about everywhere. Crossovers, stands, terminal plates, everything included. Removable covers have warping from water damage. They used to smell like cigarette smoke as well but I've had them in my garage for over a year now and I think that is mostly gone. All ribbons damaged. They stand vertical and look good from afar 😉

2. Roll of wide kapton tape (this wasn't cheap. Sourced on eBay from international seller). 0.025mm x 500MM x 33meters Amber Polyimide Kapton Film With Adhesive Single Side

3. Roll of foil (from Grainger) : Aluminum Foil Roll: 1100, 18 in Overall Wd, 50 ft Roll Lg, 0.001 in Thick, Mill, Full Hard

4. Parts to build corrugation device per AVWERK. This was tough to source, got it from a 4x4 truck parts shop.

The rest is up to you. AVWERK has a great thread in the exotic speaker forum here you can try to follow along.

Asking $1,500 for everything. Must come collect. Just want to recoup my costs. If you're up for a fun project the sky is the limit here 🙂

Please do not do the following:
1. Send me a message to kick the tires.
2. Send me a message to ask about how to go about the project. This is a DIY effort, do your own research
3. Send me a message asking if they are available - I will update this post when they are gone.
4. No pictures - don't ask.

I feel for the price this is a win-win. Price is firm - cash only.

Hello '
I custom hand build single and push pull types of Tube preamplifiers to Intigrated Amplifier's with output tubes ,using El34, KT120, El84 for push pull types out put wattage rated at 10 to 275 watts RMS. And 211 ,845 for the single ended Intigrated amplifier s preamp stages using 12AX7, 12AT7,12AU7 , E188cc types the electronic components are sourced from the best brands all point to point soldering and some with tag pcb soldering.you could email me ' or WhatsApp me on +94777145436

Put it to test how good or bad your expensive speakers are , around 05:00min :

Login to view embedded media (video in german sorry but you can switch to english in the settings , a bit tricky but works!)

Of course how strong the reaction of your speakers are , depends largely on the music you are using for this test! Use the normal playback level or somewhat higher to get a realistic impression of the unwanted noise that disturbs your high fidelity ambitions!

Easy to be done , takes no additional stuff , just some curiousity what's going on in your sound field during listening?

Why hasn't it be done as a standard test way back in history?

My suspicion is - most people fear to know how bad their speakers really are!

No excuse no more - kill all those sound devils that deceives you and take all your money , burning it in hell to torture those sinners down there 🙂

regards - death to all bad cabs 🙂

ps .. using pink noise for testing makes more sense and can be analysed to get a FR graph ...

I've had this 1979 amp and preamp pair for several years now, and I've often wondered if i can replace the near prehistoric "stereo preamplifier" ic with a modern opamp.

It sure looks to me like a dual opamp with external compensation and offset zeroing, but the datasheet is less detailed than we expect these days. For example, it says it has a differential amplifier, and does not specify which input is inverting or noninverting.

I've attempted to draw a simplified schematic, using an ne5534 as a stand-in for 1/2 of the ha1452w, and without the rest of the preamplifier input (a jfet pair) or the tone controls, etc.

Does this make sense to anyone?

I attempted to air-wire an adapter to an njm2068L but this just results in a hum at the output.

Currently fitting some ceiling speakers in my kitchen running to a TPA3118 based amplifier - all good on that side.

What I need is a receiver/device of some sort that will appear as a "Speaker" on an Apple device/Apple Music (so supports Airplay) and can stream from an Android from - generally from Spotify.

I could go down the Bluetooth route but I'd rather not as it would be good not to have to be a close distance to the receiver all the time.

I've got the hardware to setup an RPi Volumio install (Pi + DAC) (or PC + USB DAC) but that felt a little like overkill for this application.
Doesn't need to be Audiophile standard as the setup as a whole isn't.

Some devices I've seen - are they actually any good? Or a waste of money?

Audiocast M5
Wireless Receiver WR320
Arylic S10
IEAST Audiocast Pro M50

Needs to be a "Just Works" solution with good WAF.

Hi! first, english is not my main language, im a complete noob in electronics, i realy like to build mi own in ear earphones amplifier, here is my problem:

3.5mm out from a multifx processor (nux mg30) guitar pedalboard --> to a "custom" earphone (only one earphone "speaker", i recycled only one earphone from a bluethoot set and wired it to a 3.5 mm stereo jack (but it's only 1 earphone so it could be mono)

PROBLEM: master output from multifx controls both volumes: guitar outuput and earphone level.
i need independant earphone volume control, i built a passive one (it's basically a 10k logaritmic pot), but it doen't have enough volume at maximum level, i think i need an active volume control for this (an amplifier)

what's the easy and cheap way out of this? what can i build??
i've read multiple threads here, but i dont seem to find what i need since everyone is talking about "HEADphones" not earphones, i think this may be a major difference

As seen at BAF 2022!

Amazing one-of-a-kind live edge dipole loudspeaker pair made from solid slabs of Maple. Hand-crafted (by me) in the San Francisco Bay Area.

These speakers have a huge soundstage, great imaging, and high degree of overall realism. Few speakers outperform these.

This is a bargain: I am selling these at less than the material cost in order to fund (and make room for) further developments. Honestly, these are one of the best speakers I have ever made and will be sad to see them go. Unfortunately, the Eton Arcosia drivers have become difficult to source so I no longer make these.

I consider these demo/prototype units. There are some imperfections in the finish, but that adds to the rustic look. From the listening position, these are stunning to look at and hear.

Come audition in the SF Bay Area, California. Due to their size, I would prefer to sell locally. Shipping would need to be freight at the buyer's expense.

Message me on DIYAudio or buy on US Audiomart: https://www.usaudiomart.com/details...-baffle-loudspeakers-pair-demoprototype-unit/

Details: http://natursound.com/spirit.html

Drivers for sale! Make me an offer! All four are working properly. I just removed them today from a DIY speaker I purchased many years ago. I’d like them to find a new home!