Used miniDSP 4X10HD Multi-Channel Digital Signal Processor for sale. 4x inputs of which two of them is analog, 10x outputs of which 8 analog out and 2xDigital I/O.

miniDSP 4x10 Hd is a versatile multi-channel Digital Signal Processor (DSP) for analog and digital audio sources. Combining high quality audio algorithms along with a flexible software configuration, this platform follows the footsteps of our successful line of processors. With its balanced & un-balanced analog & digital audio I/O, the platform easily fits in the audio chain of most systems. Engineered for durability, the platform is packaged in a sturdy powder coated steel enclosure. The removable rack ears and thick brushed aluminum front panel match the needs of consumer (Home AV) or commercial (ProAV) installs.

Asking for 450USD for this unit.
Items location is Norway, can be shipped to nearly anywhere but, shipping is not included.

Hi,

Many popular media players (vlc, mpd, mpv etc) are using the 'ffmpeg' libraries (e.g. libavcodec) behind the scenes.
If you are writing your own audio player in Python or any other language then more likely you leverage some library which helps you to communicate with one of those players (mpd, vlc, mpv etc).

The question is how difficult it would be instead of piggy backing on those players (mpd etc) to use ffmpeg libraries through some Python binding?
I found several Python bindings for ffmpeg. Some of them just invoke ffmpeg, ffprobe, ffplay as a subprocess. But some provide real bindings for ffmpeg libraries. For example:
https://github.com/PyAV-Org/PyAV

Does anybody have experience using this kind of ffmpeg bindings for audio playback purposes?

Thanks!

I am novice, but learning fast. I would like to install a super regulator in a Crown IC 150A. This was recommended by member Jackinnj. Could someone provide more detail on the exact wiring for this upgrade.

Hello SSE builders,

I have built my SSE with both solid state and tube rectification. As per the PCB, I have added D3 and D4 in series from the HT secondary of the power transformer (Hammond 274BX) as well as the inrush current limiter. I am thinking of bypassing D3 and D4 by means of a jumper. I understand that these diodes are there to protect the GZ34 but I feel that kind of renders the tube rectifier useless as all rectification is done by d3 and d4. With the diodes in place, even if the GZ34 develops a short from anode to cathode, everything would work as usual. One would not even notice the issue. The board allows to switch to SS rectification anyway (which I tend to prefer but that is another story)

So how much damage can be expected of a rectifier tube failing? Anybody with real-world experience of the damage done by a failed rectifier? I understand the power supply caps may fail but if that is the extend of the damage, I am willing to live with the risk. I have put a 2A fuse on the primary. Do you think that is sufficient to protect the power transformer?

While on the topic, if a GZ34 arcs once, is it considered dead? My Sovtek arced the first time I powered on the amp but it was due to an accidental short on the chassis. After fixing that, it seems to work just fine.

Building Tangential Tracking Pivot Tonearms

Let me explain the title first. In my opinion, there won’t be Reed 5A tonearm without Doug Tuthill’s primary work here in the DIY audio forum. Therefore, he deserves credit for the creation of Reed 5A.

I have been studying Reed 5A and trying to design my own building plan. After many different versions of the design, I finally came up with the version I think has the smallest tracking errors. I would like to prompt criticisms and suggestions before I start to build. There are two things I paid a great deal of attention to. First, I concentrated in the playable area only. Please see the gray area in the diagram. Secondly, I tried to minimize the tracking errors.

The purpose to build a clone of Reed 5A is to approve that a tangential tracking pivot arm based on Birch geometry won’t skate. I intend to build a fully working arm without actual wiring. If one day, all of a sudden, I have eager to listen to this arm, I can simply wire the arm up and have a listen.

In theory, Birch geometry is not perfect. Therefore, there are some small tracking errors. As long as the tracking error exists, it means that side force exists. But in reality, such side forces are so small that they are not strong enough to cause arm skating. So, an arm based on Birch geometry won’t skate in reality. This is all I care about. For my arm, the largest tracking error is 0.1 degrees. In the diagram, the largest tracking error exists the most inner groove. If in actual use, I can align the arm so that the largest tracking error will be on the most outer groove since it is easy to play the most outer groove. Please see the diagram for tracking error analysis.

Comparing Reed 5A with my design, I think my arm has less tracking errors than Reed 5A. Of course, I can be wrong since I don’t have the data for Reed 5A. All the analyses are based on the screen catch from the video of Reed 5A.

I am going to build the arm and all the results will be posted under this thread.

After building the first Lil' Pucker I quite enjoyed the process and wanted to refine it a bit. So this version is 3d printed and coming along well. Upgraded to an Arduino/SimpleFOC drive system and it is much more stable. Have an audio sample here. Login to view embedded media

EV T25 mid hour with packing on back .
199$ plus shipping
thanks Rick

Apparently being sold by an asset disposal/recycling company? This makes me wonder who had all this to begin with?

https://www.ebay.com/str/electronicdistributorsintl

I've been experimenting with OB for a while now. System is sealed 12" subs, 18" OB midbass, 8" OB midrange, AMT OB tweeters. Up until recently I wasn't super happy with OB midbass (mostly missing sense of impact) and was almost ready to go back to sealed, but added 2 additional 12" subs to the two I had, applied MSO, and now I'm happy with subs playing up to 80Hz.

System is active with digital xo on Acourate. When I run the correction routine, I see a sharp drop in raw response right before 300Hz that ends up being corrected by Acourate, but still bugs me that such a big drop is there. The 8PE21 midrange struggles to go much below 300Hz in the 30cm OB I have it on, so for now I xo at 300Hz and let Acourate correct.



I took some in-room measurements of the midbass to get a better feeling of what I have. Measurements are taken from the listening position, no IR windowing (500ms), speaker on its usual location. Far from ideal, but I haven't figured out how to measure an OB (in-room nearfield with windowing misses the backwave, and so does measurement outside plus it's a hassle in a large city like where I'm at).


Blue is how I'm running the 18". While it says H for the baffle, the structure where the mids/tweeter sits is separated from the floating midbass panel and the midbass was close to the front edge so it was more of a U open baffle than an H. With 1/12 smoothing it shows a 94.8dB at 231Hz, dropping to 71.1dB at 288Hz.

Orange is with the 18" baffle on the floor as usual, but I removed the midrange/tweeters and "H" (or U) structure around it. The dipole peak went up to 95.8dB at 242Hz - makes sense that with a smaller baffle the dipole peak raised the frequency at which it manifests. Interestingly, the gain I am getting on the lower end is less than I expected: about 2dB at 80Hz. The 18" Faital is quite efficient and a 400W class D driving it would have no issues compensating this with added power, so I'm thinking the H (or U) isn't helping much here.

The green line is with the speaker on the same location, but placed on top of a chair with minimal backrest (so it's acoustically transparent). I found this measurement quite interesting: It didn't drop below the orange (panel sitting on floor) on the lower range yet the dipole peak dropped by 8dB.

All measurement display a null around 210Hz and another at 139Hz. I wonder what might cause these?

I'm concluding:

• I don't need the H/U baffle as there is minimal gain in the lower end. I'm not seeing evidence of the cavity creating nulls either, but there seems to be no upside to having the H/U.
• As expected, a smaller baffle raises the dipole peak frequency.
• Raising the panel from the floor seems to diminish the amplitude of the peak at the dipole peak.

A next step would be to make a smaller baffle (to increase the dipole peak frequency) and raise it from the floor (to reduce the amplitude of the peak).
And maybe when I'm done with improving the midbass I would try a larger midrange baffle to make it reach 250Hz.

Am I on the right track, or misleading myself from improper measurements, or other?

Who does not want i2s to make NOS on most popupal cd players on the word ? Everybody who know how mutch resampling made by digital filter degradates analog sound !!! I am one of them ... I have Cd46 . I know that if we install there memory chip which send to adress 0011 data 1010 ( page 12 SAA7345 datasheet ) than saa7345 will starts send to dac sygnal in clear i2s format. Please help how to reach that goal!!! Please try do not post suspect working solutions or alternative ones as" maybe better use oversampling " or " another format be better" but try write most accurate about SAA 7345 reprogramming. Thank You.

I have 3 pairs of new prototype speaker cabinets finished in rosewood veneer. These were samples made by a vendor that we decided not to go with for a commercial speaker.

Cabinets are 22cm W x 40cm H x 33cm deep.

145mm dia woofer cutout with 175mm dia bezel rebate.

Tweeter cutout for bezel is 66mm W x 88mm H.

Passive radiator bezel is 123mm W x 198mm H.

Binding post panel bezel is 85mm W x 123mm H.

You are on your own for finding drivers and passive radiators as they were custom or OEM. However, someone with a jigsaw can easily cut the tweeter hole to fit a standard ribbon or dome. The woofer is pretty standard and bezel from RS180 should fit.

Cabinet is 18mm MDF on all sides but front is 36mm thick. Deep bevels for reduced diffraction.

Snap on cloth grills included. The veneer has some surface blemishes - not perfect but not a bad looking speaker for casual home use.

Local pickup only please. Northern Virginia / Metro Wash. DC area.

Send me a PM if you are interested. All 3 pairs available for grabs.

Hi,

I had been using an X-10D clone which has wiped out both my tweeters and amp 😡

I'm using a different amp till I have time to look at the other one, but have replaced the tweeters and they sound ear bleedingly bright 😵

The tweeters are known good taken from another set I have and are the same Audax HD100 D25 8 ohms, reading 6.2 on my dmm (I also tried another pair, which are doing exactly the same) so I can only think something has happened to the crossovers. There is nothing visibly burnt, or charred - any suggestions as to what this could be, or to check?

Thanks.

Good morning everyone. So for sale is a nice pair of Studio 20 book shelf speakers in black ash finish. They are 12 years old if I remember correctly? They use a Seas coaxial driver with a silk dome tweeter. The drivers are in mint and have no pokes to the tweeter or rotting surrounds on the woofers. The drivers work perfectly. The cabinet’s are in good shape and have some marks and scratches on top and a few here and there. I would rate them a 7. They are heavy and buyer is responsible for having the speakers boxed up and shipped. I can take them to my local Fedex or UPS Center and the rest is up to the buyer. There are No grills or paper work or original boxes or bottom cabinet spikes. I Can meet up if needed and send videos of the speakers playing. To be honest am selling to pay for another bill. Am asking $100.00 a pair Please E mail me with offers or any questions you have regarding these speakers. This is my e mail address Jmboo1922@gmail.com.
Thanks and be safe. Jeff

Hi everyone,

Please help me, what do you think, In the time to come I will build an open baffle speaker, the dimension of the baffle is not a problem because I have an MDF in unlimited dimensions...
Baffle for F15 would be somewhere about 60x120cm (or similar to Decware bigger dimensions..) and for the Manzanita precisely as well documentated on DIY forum...
So, it will be a project for a Solid-state amp, I have a Yamaha RN-602, and later maybe I would like to add a cheaper tube amp as ELEKIT TU 8100 or some push-pull from Nobsound or Douk Audio....but this will come only if a decision to go with Lii F15 which is preferable for tube amp...
Now, my main doubt is that I would like to go with Lii F15 from the start because the full range and no crossover is something that I would like to hear and try. After all, I am 50 years old and all of my life I am listening to a 2 or 3-way speaker (last 7 years I have JBL Studio 530 on this Yammi stereo receiver), but I don't know will it sounds good on SS amp, because all over the net is full of excellent review for this F15 driver but only with a tube amp, regardless their high sensibility, etc...
Maybe someone has tried to pair this F15 driver to an SS amp, so your opinion would be great...
On other hand, I see that many people are really satisfied with the Manzanita speaker, but if I build these, later tube amp upgrade is out of the question, as I see they are not for tube amplification...
Or, to make it simpler, maybe you have some other idea for a full range open baffle that would work well with SS and tube amp...400-500 EUR for the drivers is ok...

Thank you very much for your time in reading this...and thank you for this wonderful forum site, I am reading here post for more than a decade now...thank you all...

I’m looking for the service manual, or just the schematic, for the Quad 606 Mk 2. Is see 606 manuals and schematics on line, but nothing on the Mk2. Can anyone help?

Thanks in advance.

Hello everyone,

I am building a small guitar valve amplifier (this will matter later), and I will include a power attenuator. I have dedicated a heatsink to the attenuator part, and my question is whether there will be a significant difference in thermal spreading if I attach the power resistors directly on the heatsink (cutting a large chassis area off) or if was to leave the chassis sit in between.

I attach a detailed plan of the two placements. The chassis is made of 2mm AlMg3 (Aluminum 5754) and its total dimensions are 490 x 200 x 65mm. Since the amp is a guitar combo, all valves (and the heatsink) will be facing downwards - thus, I expect the chassis to get a bit warm or hot, regardless of the attenuator usage. The heatsink is bare aluminum, having a theoretical thermal resistance of about 1 C/W.

Correct me if I'm wrong: I assume that in the case of leaving the chassis sandwiched between heatsink and resistors, I will get a poorer thermal transfer to the heatsink, but "gain" a bit thermal spreading on the chassis. Whereas on the other case, thermal spreading to the chassis will be minimum, and transfer to the heatsink maximum. Do you think that the two solutions will differ significantly in:
(1) steady state resistor temperature
(2) steady state chassis temperature?

I understand that usually, you mount everything directly to the heatsink, but I was wondering if this could really make a difference here. Also, is there a way of calculating the thermal resistance values for the application? I tried some online calculators but got very different results.

Thanks!

Hi, Anyone has the power supply diagram with main trans connection (showing the wire color) connected to where?
Bought an unit and the main trans connection mixed up so I am trying to get it right to the original connection.
Appreciate anyone help.
Thank you.

Looking for the chassis. These are unavailable at the diyaudiostore and are very expensive if purchasing through hifi2000.

I think I have a floor bounce cancellation and know that adding a second woofer further down the (floor standing) cabinet can help with that. I am also considering adding a port to help the LF and was thinking if I put the port lower down the front of the cabinet it would have the same effect?

Hi All,

I have 4 unused never installed Toroidy Supreme Audio transformers each with side wiring plate.

2 each 300VA PRI 230V / SEC 2x45V 3A
1 each 60VA PRI 230V / SEC 260V 0.12A and 2x 6.3V 2A
1 each 50VA PRI 230V / SEC 2x 7V 3.5A

EUR 50 each plus shipping to your European destination. They will ship from Germany.

Best,
Mike

Has anyone out in webland got a schematic for the little front end daughterboards used in the 7.250 to convert from balanced (XLR) to unbalanced. I know this SHOULD be dead simple bot the boards contain a bunch of other semis whose function I cannot determine. Amp came in with a deceased THAT1250 which is a very rare beast indeed and theoretically interchangeable with a SSM2141 (which I stock). Regrettably the theoretical did not match the practical and the SSM did not work well.

Looking to buy Iso Tango SA-300 or similar transformer. Need up to -20db attenuation. Shipped to Los Angeles area, California, USA.

I decided to buy a few 5C8S rectifier tubes to experiment with because they look cool but also handle a good bit of current, double that of a 5AR4. They're still in transit but I'm studying the specs. Using a translate app to read the datasheet it's saying the capacitor input value should be 4uf? That seems very low for a tube rated for this much current. It's indirectly heated so the startup should be slow enough. Wonder how they came to that figure? https://frank.pocnet.net/sheets/084/5/5C8S.pdf

This player is a Sony CDP397. Inside is mostly empty space. It uses a CXD2500, which produces a set of signals similar but not exactly I2S, which is what the TDA1543 (the new DAC chip) expects. The main issue is that the LRCK signal changes state too early, by 8 sample bit clocks. The TDA1543 grabs the first 16 bits it sees when this LRCK changes state, and ignores any more bits that come along. Thing is, the CXD2500 runs a bit clock 24 cycles times the "word" length. Instead of 16 times the TDA1543 expected. The CXD2500 sends the MSB bit for teh first 8 clocks, then the rest of the bits. But the TDA1543 grabbed 8 bits of MSB and then the next top 8 bits of audio data, which made the sound very low, and would sound like 9 bit audio, yucky. To get around this I decided to build a delay circuit to make a new "WS" (thats what the TDA1543 calls the LRCK signal) off a counter counting out 7 cycles of sample clock, that in turn triggers a latch to grab the state of LRCK and assert it onto a new WS signal that then feeds the TDA1543. This in turn makes the TDA1543 grab all the audio bits correctly.

I didn't remove the old DAC chip (one of those noise shaping thingies) out of the player, it feeds the headphones, and it houses the master timing oscillator.
I haven't built the tube circuit just yet, as I need to round up a power supply for it. Now I'm feeding the DAC output to an audio amp for testing.

The hacked up board used to be a piece of a PC soundcard, one that used the TDA1543.

After reading a couple of threads, mainly centered around the slot-loaded open baffle design, I wondered if there was a sealed design which would allow drivers to be mounted facing each other.

The only real reason for this was instead of having a line source of drivers that resulted in a tall box, could the effective height of the box be halved using, say, a 2x2 arrangement rather than a 1x4 line source? The volume of the box would need to be compensated elsewhere, so maybe this hasn't been explored much.

The idea can be seen in diagram.
This is only a basic simplyfied schematic. I post in more details later.
Should be noted that these circuits are so far only in my SPICE.
But should work good and give fine performance.

Power chip OPA541 can fead 50 Watt into 8 Ohm.
Max rails are for the chip +/-35 = 70 Volt.
Here I run 6DJ8 and OPA541 at 66 Volt.
Even if OPA541 can amplify voltage, in this case it is used as buffer.
Voltage follower at unity gain.
What come in comes out to speakers.
Distortion is low and can not be perceived as effecting sound.

This means that 6DJ8 totally dominate the distortion, the effects on sound signal.

There are 2 alternative circuits.
One where Triode plateload is resistor, 100kOhm.
One where Triode plateload is a CCS constant current source.
Big difference where CCS gives near hifi performance
and resistor load gives more Triode Tube sound.

Enjoy 🙂

In an attempt to slightly upgrade the quality of the lowpass filters I usually use, I got me two of these: https://nl.aliexpress.com/item/1005...t_main.47.21ef79d2zUlmi4&gatewayAdapt=glo2nld
The picture shows it next to the other filters I have in my spare drawer:

The left one needs 12V DC, the other two between 9-0-9 and 12-0-12V AC power supply. Only the center one has 'proper' Voltage regulators on board.

I connected one board to a mono amp and used the combo to power my subwoofer in the living room, worked fine.

But, after a few hours powered up, the volume potentiometer produced scratching noises when turned, loud enough to be heard over the music. Weird.
Turning the board off and on again the next day made no difference, the scratching was here to stay, no big deal as long as you don't turn it...

Out of curiousity, I swapped the first board for the second one and the same thing happened; after a few hours of working fine, with a silent operating pot, this one also started scratching.

I suspected DC offset, so I measured the Voltage over the outer legs of both pots: 4,45V DC on the first and 4,2V DC on the second board.
The first measurement was with the input and amp attached, so the DC could have come from my input signal (PC soundcard in my shed and the sub out in the living). The second board was measured with nothing else than the power supply connected.

I've contacted the vendor and asked for a schematic, to be able to check things out.

But this is odd, isn't it? Over 4V DC over the volume pot on both boards. No, I didn't measure prior to both boards developing the scratch..

Ideas, suggestions?

Regards, Jan.

Hi everyone, I bought from eBay a pair of iTeufel box monitor speakers, sold as not working (but I was planning to use them to make a DIY soundbar). That said, I plugged the main speaker and it was actually working, but with a 100hz loud hum. I thought after reading some forums that replacing the 2 main capacitor would have solved the problem (even if the old capacitors that were on wasn't looking bad at all) so I bought 2 new capacitor and put them on.
After the replacement, sure that the hum would have disappeared, I plugged the speakers, but the hum still there 🙁
I tried to check everything, I am pretty sure that is an amp problem and not a ground loop, but I am here as a learner to learn what the problem could be!
I'll attach some photos of the amplifier, but if you need more, feel free to ask for them 😊
Thanks, Marco

I am currently making a component shopping list for the 5/10. For the high-stability resistors (R4+5), I found a metal film type for these at 1%, am I going down the right road or is there something better? As for the remainder, apart from the volt droppers (R7,14+22), would it be OK to use the same as (to keep the supplier down to a minimum), as for the wattage, would Ibe doing any harm by increasing the 0.25 w to 0.5w and so on. My only thought is the cathode load resistors ( R18+19)

Finally had time to test this out. I initially powered it up with Variac, then just plugged it in. You probably have to adjust the dBref for HP, LP and BP.

My naive thought is that the original power supply would have a transformer that accepts 220v and outputs X, which the rest of the PSU circuit can handle. So, it would seem that replacing the transformer with one that accepts 110v and outputs X would work, since the rest of the circuit would see the same voltage. Am I misunderstanding something?

Hello everyone!
It's been a while since I've been lurking on diyAudio, observing what's going on. I'm glad I finally have a good reason to post!

I moved from France to Canada and had to leave my pair of Atlantis Lab behind. Immediately, the idea of getting a new pair while waiting for the other one to arrive from overseas sparked my desire to build one myself for the first time.

Objective​

My goal is to build a pair of studio monitors for sound editing and mixing. It's obvious to this knowledgeable community that it's an ambitious project, especially considering my first constraint. Nonetheless, it remains the guiding principle and the purpose for which I will ultimately use them.
Before we continue, I want to emphasize that I am fully aware that what I am about to present is merely a projection. None of what is established here will definitively tell me how these speakers will actually sound. However, one has to start somewhere, and it's best to start off in the right direction.

Constraints​

As mentioned in the introduction, this is my first DIY design project. I've learned a lot during these initial design phases that led me to post this thread, and I know I'll learn even more once I get my hands dirty. The first constraint is the price. I don't want to break the bank by making mistakes (especially correcting them) on my first project.
The second constraint is the size. I want to be able to place these monitors on a desk or on stands, in a near-field setup.
The last constraint, closely related to the objective, is the linearity in the speakers' response.

Used Transducers​

I came across the Visaton WS17E and Visaton SC10N on Solen.ca while browsing the site in search of the ideal combination for a beginner. The price constraint made me consider Dayton Audio for a long time. However, the Visaton speakers caught my curiosity, and it took me longer than I care to admit to ask the relevant question: Is there already a documented project using them?
Without further suspense, Visaton themselves propose the CLOU design.

You'll see that this project only shares the transducers and part of the enclosure with the original CLOU design. I'm not sure yet if that's a good thing.

Crossover​

From the start, I know that the linearity constraint will be difficult to meet. But we’ll do what we can.
I'm using VituixCAD. The amplitude and impedance response curves were obtained using FDGraphTracer from the speaker specsheets provided by Visaton. I started by recreating the network presented for CLOU, but the resulting crossover was far from satisfactory.

CLOU original cross-over network


CLOU resulting SPL response

I went back and forth with FDGraphTracer multiple times, double-checking the value and placement of the components to ensure it wasn't an error. So, I made the decision to design it from scratch.

I began by adding a source-side resistor to compensate for the sensitivity difference between the two transducers.
It quickly became evident that a first-order filter would not be sufficient for either of the transducers.
To my surprise, a second-order high-pass and low-pass filter was enough to achieve what appears to be an acceptable response. You'll notice that I had to reverse the polarity of the tweeter to achieve this result.
The Total SPL graph shows a curve of ±3dB between 60 Hz and 17000 Hz (78.2dB ~ 81.7dB).

Project cross-over network


Project Total SPL, separate SPL and Normal Phase


Project transfer functions


Project group delay and separate phase


Project load impedance


Project null reverse with tweeter polarity switched

Box​

The original CLOU design is a tower speaker with two woofers. One woofer is placed in a sealed box near the tweeter, while the other is separated in a larger box that serves as the base of the speaker. This larger box, below the sealed one, has a hole near the base. I'm unsure if it's a simple hole, a port location, or a cutout for the terminal.

My design eliminates the lower portion, including one of the woofers, and only retains the sealed box. Using 16mm panels, the same as CLOU, the external dimensions are 220mm W x 331mm H x 320mm D, with an approximate volume of 16100cm³, excluding the space occupied by the speakers, shelf bracing, and other components.
An absorbing material will also be added. I will determine the quantity during actual measurements.
VituixCAD's enclosure design tool calculates, for a box of this volume and this woofer, a curve with a resonance of +2.5dB at 80 Hz.

SketchUp preview of the box


Box projected response

Conclusion​

We've reached the end of the project presentation. I'm genuinely eager to receive your feedback. Please feel free to ask questions and share any remarks or comments.

While I enjoyed the process to get here after many explorations with other speakers and box types, I'm still uncertain about the robustness of these plans.

Some questions I currently have are:

• I have a network in stock that includes a baffle step corrector. Is it wise to consider integrating it at this stage of the design?
• I'm concerned about the load impedance curve. Should I incorporate an impedance corrector into the network?
• I haven't considered any Z-axis offset. Is it worth it to add a ladder delay network?
• Should I be worried about the box resonance anticipated by the software? If so, what should I consider doing? Install a Variovent to virtualy add volume to the box?

As you know Scottmoose has been helping out with MJK sims of the Frugel-Horn (since MJK as yet doesn't do 1/8 space these are only of interest as a design reference when compared against one another)

Anyway, this spurred Scott towards implementing some of the stuff floating around in his brain and has spawned a new member of the Frugel Family... if the original Frugel-Horn is the mama, this is the tall-gangly -- but smart -- teenager.

Inspired by Terry Cain's double mouth BEN series, the Replikon (discussed here http://www.diyaudio.com/forums/showthread.php?s=&threadid=55721 and conversations with GM about the big box (CC) long exponential port bass reflex style horn as respresented by the Replikon, Scott came up with a box that is very tolerent of differing driver parameters. It also requires no curves to be cut.

Scott is building the 1st prototypes now, and will hopefully get a chance to let them get a listen at the upcoming EggFest.

The working name for this horn was the FrugelBEN, but unless Terry Cain gives his blessing, we'll need to come up with a different catchy name -- DoubleFrugel is kinda derivative.

I haven't got detailed plans ready yet, but i will, in the next series of posts, attach some teasres.

dave

Operly Intelligence III Horn Speakers​

https://www.stereonet.com/uk/news/operly-intelligence-iii-horn-speakers-now-available



67Kg/speaker 572 x L 590 x 800mm (WxHxD) vaccume formed 15mm high quality fiberglass monocoque body

You don't want to know what they cost!

@planet10 @Scottmoose @nandappe etc How about a few Front/Back DIY designs?

Hello, I was hoping to hear from any of you that have ventured into building a stereo tube amp, and what you settled on for a 19" rack mount chassis.
For the amp I am designed up now, I plan to build this on a 1U (or maybe 2U) rackmount chassis in the vintage style, with all tubes/transformers/choke/maybe filter caps located on the top with preampboards, control pots, switches within the chassis.
I've been looking at Par-metal and see that there are 3-4 series to choose from - alum/steel, alum on only, Heavy duty alum/EMI RF protection.
Its obvious that for a 100W 2-channel tube power amp, there will be a considerable amount of weight that the tops of these chassis will need to support.
I should probably add that this will likely need at least a 10" depth. And a 1U height will probably be enough to fit preamp boards/switches/potentiometers/jacks, etc...
Were you led to purchase any particular brand/model that provided enough structural rigidity to support the weight of transformers?

Thank you for sharing your experience.
Best,

Phil Donovan

There is a product that can be applied to the inner surface of horns or tapered drive lines to improve performance. I am not referring to rumble dampener.
I am thinking, for example, of the rebounds of acoustic waves against the walls. it probably doesn't exist otherwise it would have already been done by the producers, but you never know and it doesn't cost anything to ask.
Thank you

Hello,

I run into trouble to tighten the fixation of the lift,the antiskating and arm standby...

Please have look to the picture enclosed,the second one at the rear shows the hole where you can guess the main bearing allowing the arm movement.. (1)
So ,the support of the three mechanisms listed upside should be fixed thanks to a screw probably hidden by the bearing .

I've tried to dismounting the parts but I failed and i suspect the needs of a specific tools to operate...

Should you own the same arm, please let me know if the mounting looks to be similar

Thanks in advance for any advise, I do not have the adress of Helius service...

Kind regards

Raymond (from center of France

I recently started this thread asking about how to build a vented box for some alpine drivers.

Some people recommended here and on Reddit that I go for a sealed box instead.

The manufacturer recommends a 0.85 ft³ box as the ideal of a recommended range of 0.5-1.5ft³

WinISD tells me F3 will be 45hz for those sizes, though at 20Hz, a 50L box will be around -14dB and a 35L box will be at -15.5dB. Qtc will be 0.772 for the small box and 0.709 for a 50L one.

50L is not much larger than the recommended 35, but it's a bit larger than the recommended maximum 1.5ft3 (42L). And it fits the mythical 0.707 Qtc

Is this a reasonable box for a HT system? I plan on having 2 of them in a small room. Considering room gain and 500W RMS to each, the total SPL at 20Hz should be 107dB at 20hz (115dB after 45Hz)

Kids bought an old Magnavox console at a yard sale.

I am opining that the turntable is one level above a Victrola and should not touch their records.

The radio portion says Solid State.

I don't expect the speakers to be anything other than 'interesting'.

It might get turned into a piece of cat furniture, but I would like to search for a manual...except I can't find a model number on the outside.

Maybe inside the rear Masonite panel?

There pulls or knobs on the front, but they seem to be decorative only.

Thanks for any assistance finding secret markings

Murray

As per title , I would be most pleased to discuss any offers via PM please or FelixKat@gmail.com

I'm beginning a recap on an SL-10. I know the white stripe on Blue Instrument Device caps represents the positive lead unlike conventional markings. What about the caps wrapped in black with a Threshold logo? Does the "Threshold" represent the positive or negative lead?

I have not pulled the PCB yet. It looks a little tricky to trace since this is the power supply regulation circuitry and I have 4 caps on each side in opposite orientation. I think I'd need to trace them back to the 7815 or 7915 to determine polarity.

I was hoping someone had done this already and could spare me the hassle!


Thanks,

Eric M.

In the past, I purchased a bunch of 6V low-dropout 6V regs in TO92 case.
For the life of me, can't find the datasheet for the pinout.
(LDO pinout used to vary between manu's).

Anyone can help me out?
I can find SMD version pinouts but not the TO92 pinout I have.

Jan

Do we start the sweeps on mids and tweeters with some LF cutoff to protect them?
Was thinking maybe 500 for the tweeter and 50 for the mid, just so they don't try to do the lowest octaves.

Hello there.

I am looking for a a virtual device in Windows that loops through an output that allows me to change volume.

Virtual Audio Cable would have been perfect, but I tried it and its volume sliders sadly have no effect.

Maybe someone knows something with the functionality I'm looking for.

Regards
Stoneeh

I a/b tested my monitor 7s against my other speakers and found the tweeters sound dull compared to everything else. I can't help but notice it now and although I'm not in a place to upgrade, I've read that replacing the capacitors can be a quick fix. I think they're 20-25 years old, but couldn't find an exact date. I looked at the crossover and saw each speaker had two capacitors, 6.8uf 100v and 22mf 100vdc.(could be 22mfd, but it was hard to see)

I could easily find replacements for the 6.8uf, but I'm confused by the 22mf. Is this the same as a 22uf 100v capacitor?

Surviving a sudden and highly disruptive relocation five years ago, I am happily back on track with PierreQuiRoule and Troy Crowe to build our version of Gary Dahl's Beyond the Ariel speakers.

https://www.diyaudio.com/community/threads/beyond-the-ariel.100392/page-648#post-4399839

https://www.diyaudio.com/community/threads/beyond-the-ariel.100392/page-354#post-2267501

Jim Salk had cloned Gary's 3 cu ft sealed Altec 416-8B midwoofers to also play down to 70Hz. https://www.salksound.com/
But we are using different horn drivers, horns, tweeters and subs.

So, I have a pair of the 16 ohm drivers for sale: https://www.usspeaker.com/radian 745neoBepb-1.htm

And a pair of the AH425 horns: https://www.azurahorn.com/azurahorn_horns.html

A good price can be had for this package only deal.

Furthermore, Gary had posted the original AND final crossover circuit at the first link. I also have a wealth of build tips I can share with you-including sketches of his low diffraction sealed midwoofer cabinets, interior photos and where to source the prebuilt curved interior sections.
I'd have to clear it with Gary, some of that with Gary, but I have at least a dozen llnks from Lynn Olson's thread where Gary gives copious measurements, design explanations and even his "on the road" show at a local hi-fi club. I can promise that it will all get your DIY juices flowing.

If intent on pursuing the build , shipment of the parts from Jim in Michigan to me in New York would be $159.00. But I will split shipping costs upon your payment for these parts.

** SOLD **

This is a DIY headphone amp using the 6C45Pi tubes, similar to the Papa Rusa or Bottlehead Mainline amps.
It has a switch for HiZ and LoZ (12:1 and 8:1 ratios)
In terms of performance, it has alot of power (500+ mW on LoZ, and over 200mW on HiZ)
The frequency response is within 1dB between 20Hz and 20kHz, with a slight high frequency tilt.
Confirmed that there is no oscillation.

The only issue is a very low-level hum that is only present when there is no signal playing. I confirmed with measurements (attached in the pics) that the hum disappears even with low level music. Due to above, the amp would work best with either dark sounding or power hungry headphones.
Lastly, the paint job is not the best and has some imperfections.

This build is a result of this fairly long thread --
https://www.diyaudio.com/community/threads/5842-headphone-amplifier.370857/page-4#post-7384124

I am building a few of these, and this was my prototype in order to iron out details for the "final" build.
This amp is using high quality parts throughout --

• Hammond 269GX power transformer and 155H choke
• Hammond 119DA output transformers
• Hammond chassis
• Nichicon LKX power supply caps
• NKK gold-plated switch
• PEC KKA volume potentiometer
• Custom cascode CCS PCB's
• Includes a matched pair of 6C45Pi tubes (matched on my uTracer)

This amp would be fairly easy to tweak, whether it is to try LED bias (or add a cathode bypass cap), new coupling caps, or even rewiring the tube sockets for a 5842 or D3A (of which I have selection if that is something you're interest in)

I am asking $350 + $20 flat-rate shipping within the US, which is well below the cost of parts.

Who actually owns a preamplifier or buffer/impedance converter that has been proven to work with the E1DA Cosmos ADC?

My input is a sensitive sound module with output of 0.2 Volts. Output impedance is 150 Ohms. It will be inputted into the E1DA Cosmos ADC which I recently acquired. But the input impedance of the E1DA is:

1.7Vrms 640Ω,
2.7Vrms 1kΩ,
3.5Vrms 1.3kΩ,
4.5Vrms 1.66kΩ,
6.7Vrms 2.46kΩ,
7.6Vrms 2.82kΩ,
8.5Vrms 3.12kΩ,
10Vrms 3.48kΩ,
43Vrms 13.6kΩ
Note: Unbalanced impedance about 30% less."

Since my source is unbalanced mono. The input impedance would be 630 Ohm less 30% = 441 Ohms and mono would be half or 220 Ohm. So at 1.7Vrms, 220 Ohm dip switch setting. A source output impedance of 150 Ohms and 0.2 Volts will be too low. I need to amplify the 0.2 Volts to say 8.5Vrms to take advantage of the 3.12 KOhm input impedance of the E1DA ADC. What preamplifier (besides the APU) or even Interface that can do that with low distortion not far from the E1DA Cosmos APU? I want alternative because the APU gain has only 34dB and 60dB select switch (with no way in between). Thanks.

I'm looking into making a WAW to use as desk speakers for my gaming PC. I have three monitors and the goal would be to have the speakers fit under my side monitors. Right now I have MTs laying on their sides, and they don't quite fit under the monitors, so they're more behind them, and it's okay...

My height constraint is about 6" but shorter would be better, maybe around 5.5". Width and depth are more forgiving. I'd say 16" wide and 12" deep, but I'd have to measure again and make sure.

Since all of the drivers have to be laid out horizontally, I like the idea of a WAW since I can run the full range down to 300-400Hz and have a woofer on each side of it without having lobing concerns. This should produce a favorable off-axis response in all directions, which is ideal since I'm not known for sitting still while at my desk. Maybe a max listening window of +/-20deg in all directions?

I've also looked at coaxials, but it seems on the budget end that a 3-4" full range will do better than budget coaxials. Which is sad, since I love coaxials. I use 15" PA coaxials for surrounds in my home theater. KEF makes nice coaxials but doesn't seem to sell the raw drivers anymore which is disappointing.

Another option is a combined mid-tweet like what Morel sells, but those are more expensive than full ranges as well and I don't think they'll do what I want...

I will have two subwoofers in the room as well so the speaker doesn't have to play THAT deep, but I'd like solid performance down to at least 80Hz to maintain some semblence of directionality.

So to sum up the constraints:

• 5.5" max box height, width 16" and depth 12" should be fine
• Woofer-FullRange-Woofer arrangement, with two discrete subwoofers
• Crossover will be active, with ideal points of 300-400Hz to the fullrange and 60-80Hz for the sub
• Max off-axis angle of 20deg, but it's variable

I like the look of the 10F/8414G10 as the full range, but they're expensive and hard to find. I have two on order from Ebay, but they won't ship till September potentially... Another option is the Peerless TC9FD as used here: https://www.diyaudio.com/community/...-waw-ref-monitor.273524/page-188#post-7077022

For the woofers I was looking at Peerless SDS 5.25" woofers since they have the flat sides which will help limit height.

Any other driver recommendations or ideas would be appreciated! Unfortunately ditching the three monitors to allow a more "normal" speaker is not a good option here...

Hi, I'm a solder slinger so I was hoping someone more design savvy could check my schematic for a basic active splitter. This was designed to connect to the output of my R2R passive preamp, Vicol Audio's Maya. I don't need gain, just current, so this is meant to be a unity gain buffer. I have some old NE5532 that I plan to use, but I'm hoping the circuit is general so I can play with OPA1612 or OPA1642 if I'm unsatisfied. I also have some old Taka A5W-K two channel signal relays, which I would like to use to switch the outputs and bypass the buffer from the front panel. I'm planning to use a standard regulated PS with 7815/7915 (+-15V). Schematic is for one channel. One question is the location of the parallel film output caps. I put them on the output of the opamp rather than at the preamp output. My idea was that this would allow the buffer bypass relay/switch to retain as much as possible the current signal path of the passive preamp. All feedback welcome. THANKS!

Hi, Magnus from Sweden here, new to the forum.
Having built my own electric guitars and amps for the past 15 odd years, I was introduced to the world of headphone amps earlier this year by a friend of mine and have just completed my first build, a Starving student II.
This build let me combine my hobbies of woodworking & electronics tinkering, thanks for having me!

This is the place to discuss the latest Pass amplifier, the BA-1, which is documented in the article here:

http://www.diyaudio.com/forums/diyaudio-com-articles/154777-burning-amplifier-ba-1-a.html

As most of you are aware, Nelson "Papa" Pass distributed a bunch of almost complete amps at the second Burning Amp Festival, lacking only the gain stage. You can read all about it here:

http://www.diyaudio.com/forums/showthread.php?s=&threadid=131663

The Burning Amps are modular in that you choose a Gain Stage and an Output stage to create the amp of your dreams.

The input "Gain Stage" section which increases the voltage can be used for any of the Burning Amps. The first gain stage is no longer in production, but the Second, confusingly called the BA-3 is available in the diyAudio Store.

So you can combine the gain stage with either one of two "Output Stages" which are also available in the Store

One output stage is single ended and the combination with a gain stage is the BA-1 Amp. The output stage consists of 2 small PCB's and two longer ones.

One output stage is complementary and the combination with a gain stage is the BA-2 Amp. The output stage also consists of 2 small PCB's and two longer ones. but they are all diff.erent than the ones for the BA-1 output stage.

Single-ended amps are quite inefficient, and only operate in pure Class A. The are the Audiophile Purist choice and probably have a small sound quality advantage, depending on your preference.

Complementary amps are more efficient, and transition smoothly from pure Class A operation to Class AB when more power is required

Nelson will be publishing a series of articles right here on diyAudio documenting designs for the various chassis that were distributed. They have different output stages so there will be at least an article for each of these configurations. That's good for us as we will have a multitude of great new designs! We will produce boards so that even people without the head start of the generous "gift of amps" will be able to make them. Nelson mentioned that these designs are to be a fundraiser for diyAudio, so the boards should only be available from here.

Recently I made a subwoofer enclosure for a 10" 250W RMS driver. The port that I have made is based on the calculation that WinISD made (6x36x90cm tuned on 31Hz) and at the first try sounds decent.

After I tried using the sub with the amplifier outside the cabinet for make some inspections. To my surprise the sub sounds a lot higher on volume and I can't still figure out why. I temporary made a hole in the back of the sub (with also the port open on the front) but the higher sound seems to be heard only in the back, not watching the front.
So I tried to make another hole in the front (covering the back one) but all returns to the original low volume sound.

I'm tiring to understand why the front port and the back hole produced so much volume in order to try to replicate it.

Hello Store:

When do you anticipate the F6 PCB and transformer kits will once again be available?

Regards,
Scott

I need to replace an LED on the front panel of a piece of equipment. I want to match the other LEDs, both in terms of color and intensity. If I am unable to get an original part from the manufacturer, what is the process to match a dead LED?

There are five other identical working LEDs on the panel I could use for reference.

Hi!

I'm looking to build a Baby Ongaku (see attached PS schematic) but the power transformer has a higher voltage secondary than what is specified (360V vs 420V/480V). Since this is my first build directly from a schematic I thought this would be a good opportunity to play with the power supply design to accommodate this transformer - both because I have it and because it's a chance to learn something.

Since the voltage on the PT secondary is higher than specified, I thought this would lend itself to a choke input - as opposed to the sorta choke input in the schematic - to drop the voltage for a B+ of 350V. I have the current at 146mA as I intend to make a stereo version of the amplifier. It doesn't seem like much will chance downstream of the power supply.

I've modeled the PS in PSUD (see attached) to the best of my ability and am curious to get some feedback. Again, this is my first PS design and there's a good chance I've missed something. To date, I've built a couple of point-to-point kits and a couple of amps from a schematic with wiring diagrams and great documentation from MJ magazine (Japan).

The things I'm the most curious about are the values for the filters, the current draw, and how the ripple looks.

Thanks in advance!

Hi all,
I have LMS and LEAP with all software, documentation and dongle. Interest? TIA...John (USA)

I have some capacitors that are supposedly PIO. They are silver. about 1.5"x1.5"x1.5" and have two solder terminals on "top". They are 1uF/750 volts. Are these ringing a bell with anyone? I've had them for about 3-4 years and I would like to use them for signal caps. Not sure if I should though.

I'm thinking about reusing 4 of these speakers that I currently have in some Keystone subwoofers since I'm doing shows in smaller clubs where front loaded could be a better fit. could someone please tell me if these figures look right? not much of a port according to the subbox.pro designer.

https://subbox.pro/en/b/aPuzX0mJS

https://www.bcspeakers.com/en/products/lf-driver/18-0/4/18tbw100-4

Hello all, I'd like to build a small monitor speaker for my bedroom with nearfield usage. I am flip flopping between two tweeters to use. I intend to use a waveguided tweeter as they simply sound much better to me, I have really grown tired of the typical dispersion mismatched 1" dome to most woofers. I intend to utilize these for mixing purposes, but also keep things within my budget (no satori stuff for instance).

My two tweeters of choice are the ND25FW and XT25/DX25+Wg300. My current main living room speakers utilize the ND25FW and I find them to be totally inoffensive tweeters that just do things right to my ears. I don't feel the need to apply corrective EQ to them and my mix translation is good. I seem to be able to work with them for hours without much in the way of fatigue and I feel they image well.

I also have in my possession a WG300 and DX25 + adapter. It appears as though the DX25 and this waveguide have a pretty rough dome reflection that causes a dip in the upper treble (I found this to be problematic) so I'd like to try the XT25. It does however look to have very narrow dispersion (referncing heismann data) but I'm not sure how much of a concern this would be.

Should I stick with what I know works well, or try for something different with the XT25+Wg300? My dumb consumer brain tells me the costlier option would offer better performance.

Some user claim, this is the best sounded commercial Class-D power amp ever.

First some URL's concerning NAD's M23 power amplifier
https://nadelectronics.com/eigentakt/
https://www.hifinews.com/content/nad-m23-class-d-power-amp
https://www.audiosciencereview.com/forum/index.php?threads/nad-m23-stereo-amplifier-review.45462/
https://bestofhighend.com/nad-m23-hybrid-digital-stereo-power-amplifier/
equipped with this modules:
https://purifi-audio.com
https://6moons.com/audioreview_articles/purifi/ (SMPS vs. 50/60Hz Toroidal
https://www.audiosciencereview.com/...easurements-of-purifi-1et400a-amplifier.7984/
https://www.audiosciencereview.com/...fi-eval1-eigentakt-class-d-amp-designs.27997/
https://www.diyaudio.com/community/threads/brainstorming-purifi-1et400a-amps.347137/
https://www.diyaudio.com/community/threads/purifi-audio-by-bruno-putzeys-and-friends.339826/

Who have heard this NAD series against old top class analog (Class A/Class AB) models ?

Hi folks,

I’m currently trying to repair a Rega Mira 1 Clamshell with a DC offset problem. The issue is that DC offset in the right channel is quickly rising when turning up the volume. DC Offset at zero volume is around 10mV. From the 8 o’clock setting the DC offset in the right channel starts rising. At around the 9 o’clock setting the DC offset has risen to ~300mV and the protection circuit kicks in.

What I've checked so far:

• Power supply seems fine. Power rails +/-15V, +/-40V measure ok with low ripple. Caps have been replaced.
• Preamplifier output looks fine so it looks like a problem in the right power amp circuit.
• When injecting a test signal, the sine waveform in both power amp channels looks fine at various volume levels (no clipping).
• I’ve checked the power transistors and compared some voltage measurements on the left and right output circuits but haven’t been able to find any obvious faults.

Any tips on how to troubleshoot this issue?
Thanks you.

PS. Circuit diagram for Rega Mira 2000 (similar): Rega Mira 2000

Hi all,

I got this vintage Japanese speaker set sometime back, it's a 50w speaker and some drivers are blown/damaged. Now I'm thinking if I could upgrade it to a better speaker meaning I'll replace drivers and crossover but keep the same cabinet.

It's external dimensions are (made of 20mm plywood)
H 62cm
W 36cm
D 31cm.

Has a 10in woofer. Would be great if I could convert this to something like Scanspeak Discovery 3w classic. Is it a worthwhile project? I have attached some pics .

Hi Tube community at DIY Audio, I was hoping to get some help. I've been very fortunate to get hold of a pair of what I'm certain are a clone of Audio Note Kegon - Balanced for a steal... I'm confident that they're made by Alp Audio, who used to be Peak Audio, who distributed Audio Note in Hong Kong.

Unfortunately, it came with two out of five tubes. I know two of the tubes are 300b's and there is a gain stage with a 6j7G (which deviates from a AN Kegon but came with amp). The Kegon is a 10Y - Interstage - 300bPSE.

It appears to be a 6j7G - Cap Coupled - unknown tube (10Y?) - to 2x 300b's. The other tube I'm unsure of is the Rectifier. I would assume it's a 5U4G, as the other amp I got is and the majority of Audio Notes amps are too.

Anyone have an idea on where to start?

Pictures say a 1000 words:

I am currently working on making an aleph m amplifier and am working on the power supply. I have some caps that are rated at 63v and this value is much higher then what my rails are for the amp. It runs at plus minus 17 volts. I could be wrong but could I not just put a cap from the + 17 to the – 17 as it would only be seeing 34v and that would be much lower than the rated value and would give me more capacitance then if I put 2 of the 63v caps in series. I looked for a few hours yesterday and could not find an answer that made me feel assured.I am currently working on making an aleph m amplifier and am working on the power supply. I have some caps that are rated at 63v and this value is much higher then what my rails are for the amp. It runs at plus minus 17 volts. I could be wrong but could I not just put a cap from the + 17 to the – 17 as it would only be seeing 34v and that would be much lower than the rated value and would give me more capacitance then if I put 2 of the 63v caps in series. I looked for a few hours yesterday and could not find an answer that made me feel assured.

I got a spare Raspberry Pi3+ and a 2.5" 500GB SSD, I am sick of the amount of cables and AC adapters not to mention my DAC which I can't stand any longer (a Beresforf Caiman SEG), I'd like to put together in a single box both a streamer and a DAC as to get rid of my Caiman SEG and the MacMini which even tho does well takes space and extra cables.

The DAC would need one-two optical inputs (one for the TV and eventually another one for the CD player even tho it's built in DAC does sound very well), dunno if an R2R or a chip based one.

Should not be hard to build a PSU to power both DAC and storage-streamer.

Do you have any suggestion to what to look at?

Grazie

Saw that JJ sell an Octal version they label EL 509s. Never looked at this tube before. I know there are the original top-plate versions out there too.

I've seen it referred to as a Sweep Tube and these are often very nice when wired up in Triode mode. But JJ provides nothing about triode wired operation.

Anybody using this tube in triode mode ? (it's not a low cost tube, not sure who is buying it in enough volume to justify JJ to keep it in production ?)

https://www.jj-electronic.com/en/el509s

Sale:

IN-1 - 54 pcs. for $2
IN-2 - 50 pcs. for $2
IN-8 – 21 pcs. for $10
IN-12 – 900 pcs. for $6
IN-14 used – 1000 pcs. for $10
IN-14 – 40 pcs. for $30
IN-16 used – 20 pcs. for $6
IN-16 – 30 pcs. for $8
IN-17 used – 35 pcs. for $6
IN-17 – 30 pcs. for $8

My first 150W amplifier using TIP2955/3055 transistors with overload protection using op-amp.
This amplifier is motivated by the need to protect the whole system against inrush current when the input signal is high. In fact, these protected amplifiers are specifically required to do some modal analysis tests in vibration labs to drive shakers. We have come across high failure rate of amplifiers due to sudden application of input signals while the shaker is connected. Therefore, I designed this circuit to limit the current of the output stage using op-amps and few other components.
I also tested it with audio signals and speakers and it worked like a charm.
THD: 0.003%
Frequency response: 1 Hz to 37 kHz
Supply voltage: +/-24 to +/-30
Lifesaver components that eliminate HF oscillation even with no load/light load condition:
1. Feedforward resistor R24 (1k)
2. Bootstrap resistors R14 and R15 (1.5k)
3. Zobel RC on the output
4. Feedback capacitor C8 (100pF)
5. Also C5 and C2 have helped a bit more.

Note: You will need a good power supply and a big heat sink for the power transistors.
Rx is wire jumper or very small resistor say 1.2R

I have a power amp that uses NE5534N op amps for the electronic balanced inputs, it is in a unity gain configuration. It looks as though these are dead and I would like to replace them with the best quality modern op amps having the same pin out. Can anyone tell me which would be the best new device in terms of sound quality? Since there are only two of them I am not too concerned about the price, quality of sound is most important.

Two very nice chassis for DIY projects. The Krell Amp Chassis is of course a knock off (Aliexpress) but is still very nice quality and great value. The silver Preamp (or small amp) chassis is super nice as well.

$250 CAD each or $400 CAD for both. Local pick up in Vancouver, BC only.

Cheers and all the best.

For those who have had the opportunity to compare both in a fairly direct capacity, what are your opinions of the largest multicell Altec horns compared with far smaller contemporary horns like a Ciare PR614 or similar at midfield living room distances of ~10-30 feet?

Looking for some right angle headers for a discrete opamp, similar to what Burson use. Easy to find straight headers that fit into standard dip sockets but no luck with angled. Is it possible Burson simply bend the pins of a straight header?

This speaker is going on action. Can anyone identify it?


Thanks,

Kelly

Hi
Looking for a high quality analog to digital converter with SPDIF output, have a Flex 8 that only has digital input and I'm trying to find a good performance ADC to connect the turntable to the minidsp.
Found two good suggestions here (ADDA24QS and nihtila.com ADCs) but both been out of stock for a while and don't seem to be in production anymore.
Thank you.

Guys,

Working on a Timpano amp, that has a bad YD7120 Mosfet driver. Wonder if , as I am searching, is the IR2092S might replace it (because its what I have)

Any thoughts?

S30 Mk II.3 OTL power amplifier

I am the first owner of the amplifier, it was bought new.

It has worked a little and is in excellent condition
I am looking for a 1700e.

UTC LS-12X Transformer Audio Rare Vintage​

Used, in excellent condition.

I am asking 500e + postage for them.

My e-mail milosnesic606@gmail.com

The relay is not engaging.I swap Q5 and 6 from a next board but no change.If I ground pin 1 of Q5 it will engage.

Any suggestions?