Hi,

My names Jim and I'm just starting to learn the basics of speaker cabinet design.

Our first project is a man portable PA built into a British army bergen (rucksack)

I'm trying to get my head around calculating the dimensions of an ordinary sealed cabinet.

The drivers we will be using are here (PDF), because they're cheap, cheerful but come with a set of thiele small numbers.

I've used a calculator I found here (web page)
That worries me though because it's completely black box and is named as a designer for subwoofer enclosures. I don't know whether the maths is different for full range speakers.

Anyway, the bag minus batteries and amp leaves us with about 50liters of space for the cabinet.

Now, putting the numbers into that calculator get me a Qtc of 1.

So far I've read that you're supposed to aim for 0.707 but 0.5 to 1.2 is a usable range.

Unfortunately I don't have all the measurements and dimensions to hand, but I keep not getting round to making this post so I'm just taking the plunge.

Sound quality is not top priority in this project, it's just slightly behind:

1) Cost, apart from the fact nobody has much cash to throw around, the Mark 1 Noisy Bag is intended to be followed by more refined designs so we don't want to spend too much on something that will probably be just the first attempt.

2) Just Getting It Done. Seriously, we've been procrastinating for about 2 years now. It's time to get the hammers out.

3) And then sound quality, because there's no point in putting in all this effort/money if it's going to sound bad.

In fact it's really about striking a balance between all of the above 3 factors.
Speed, Quality and Cost.
Hmm, wait a minute, that reminds me of an old adage... ;-)

Anyway, I'll try to draw up and post some more details this evening (can I upload napkins and fag packets, back of? Does that work 😉 )

Anyway, thanks for reading the ramble.

J.

Hi there!

So I have this subwoofer box here, and I don't really know what type of box this is?
Is it a bandpass like it says in the PDF drawing? but that doesn't seem to match the illustration in WinISD.
Or is it just a normal vented enclosure with 2 woofers?

I've drawn blue circles around the vents in the front.
Also, my subs aren't loaded with JBL's, like stated in the drawing, but with Eminence Kappa-15LFA's



Thanks in advance!

I am new with Xsim this week 🙂

This is my project and i appreciate advice of how i use Xsim and develope a passive filter.

BTW, i have tested this speaker with active crossover (miniDSP HD2x4) and it sound awsome.

Bună seara. Am 2 boxe active alto ts 315 iar una din ele a început să-mi facă figuri. După 2 minute basul se întrerupea și revenea apoi. Am refăcut toate lipiturile de pe cablaj , iar acum funcționează dar nu la fel ca cealaltă. La pornire prima dată se aude twetter-ul iar după 2 secunde și wofer-ul plus ca la volum mare cînd î-i dau bass am distorsiuni. Va rog frumos să-mi dați ceva detalii , ce piese trebuie schimbate etc. Mulțumesc anticipat

I would like to us a Sowter 8920F 10k:10k+10k SUT at the input of a CF/buffer line amp, The 8920 is designed for phase splitting duty, but can also used as a stepup, Sowter show the termination to be 20k + 20k per secondary , If the volumn control is placed after the SUT do I need a 40k item, or will 50k be ok or what? Thanks John

I have created a spice simulation using the RIAA phono preamp from the RCA tube manual.
Included is reverse RIAA network, the Jung-Lipshitz Improved inverse RIAA
Network (From original TAA article).

Two signal generators or on the sim a 1kHz sine wave and a 1kHz square wave.
The waveforms show a square wave fed into the preamp, the output of the RIAA and the restored
square wave out of the inverse network.

I'm certain a better spice model for the tube could be used.
Please feel free to improve on this work and repost.
The original RCA component designators were used.

https://hifisonix.com/wordpress/wp-content/uploads/2016/12/Accurate-Inverse-RIAA.pdf

Ken K

I just bought out the last 4 LM329B's at Digikey, and they have 36 LM329A's left. Octopart shows no more available from the usual reliable sources.

The LM329 is at the heart of the GFA-565; They are essential parts for my BFA-565 circuit board kits, and I'm not sure what to replace it with! I have a couple ideas I would love some feedback on.

In a nutshell, the LM329 in the GFA-565 is doing double-duty. It's set up as a simple shunt regulator, with two 6.9V references in series for 13.8V output.
1. It supplies +/-13.8V power to the servo op-amp, consuming about 0.5ma per rail.
2. It supplies +/- 13.8V base reference voltage to the cascodes.

Schematic:


What are the important parameters here?

• Low noise obviously. The LM329 is hard to beat in that respect.
• Dynamic impedance: Does this matter to the bases of the cascodes? The LM329 is around 1 ohm dynamic impedance.

I suppose thermal coefficient is not really so important in this application. The servo can keep on top of the drift.

I have two ideas, both based on publications by Walt Jung himself, who incidentally, designed the GFA-565 circuit, so if one of these two solutions works out, it would be true to form.

1. Walt wrote an app note in 2019 describing the use of two 1N5234B zener diodes in series, with one forward and one reverse, for a combined Vf of 6.8V and a noise density even better than the LM329, around 20nV/Hz. One concern I can imagine, is the dynamic impedance of the zener is about 7ohms, so am I correct that the output impedance would be 7 ohms in series with impedance of the second, 0.6V forward-biased diode? Is it also 7 ohms in the forward-biased diode?

2. The "PM329" Zener-Based 6.9V Shunt Voltage Reference


This is a really interesting option to me, and it seems it would easily exceed requirements. There is a 13V version of this diode, the 1N5243B, which would make this a 13.6V reference, and so it would not need two references in series as OEM.

The first option would be simple and dirt cheap, two diodes in series, and if it's truly as good as the LM329 in this application, then great! But I'll do the PM329 discrete solution if that's best... I'm not sure I know what all the most important parameters to consider here, opinions requested...

hey guys

what are your favorite modern 5 or 6 inch wideband?

thanks!

Selling some dac stuff:

2x TDA1541A S1 : HSH8805 : SOLD These were pulled by myself out of cd-players (Creek CD60 and Orelle CD-160) so I assume they are genuine. I have used/tested them in my tda1541a dac and their sound is substantially better than the regular 80s/mid 90s tda1541a and I also prefer them over the late 90s tda1541a's (which are a bit too 'crispy' to my ear)

1x Abbas Tube Dem clock for tda1541a :SOLD

1x Tribute Autoformer Volume control SOLD : Stereo Autoformer volume control, with 2x autoformers and ELNa selector switch

2x Andrea Mori low phase noise clocks SOLD Pierce oscillator (2nd best model of the lineup) 5.6448 MHz & 6.144 MHz, including hammond boxes and crystals

1x pair of Bisesik output transformers for DAC, SOLD
Ratio 1:16
1primary, 1 secondary
Big version=bigger bandwidth
PCB designed by Ivan, with 2x hand wound I/V resistors (33 Ohm) and a buffer output stage, consisting of 2xpairs matched Toshiba SJ74, SK170 for low output impedance

1x IanCanada FifpoQ3 : SOLD : FIFO reclocker for raspberry Pi, 2x Accusilicon clocks optional for SOLD
1x ReclockPi : SOLD
1x Sinepi : SOLD : converts sine to square wave, for clocks

1x RyanJ board for tda1541a simultaneous mode / mangled, but working perfectly= missing some ufl connectors / SOLD

Selling all due to buying the latest model dac by ECdesigns, causing me to stop trying to improve (let alone use) my tda1541a dac...

Here's the thing I keep designing the same amp. Need 100W per channel for the room. So my output stage is PP UL with 2x6550A on each half - a total of 8 6550A's and 12A of heater current for stereo.

So what a about a couple of KT120/KT150. Would look nice/something different. But I to get the same output power HT needs to go up (from 440 to 600V). I end up with the same issue. I need so much bias current to eliminate crossover distortion I will end up red plating the tubes - at least in simulation. There does not seem to be a better solution than two KT88/6550A in parallel. Am I missing something.

Hello,

Does anyone know of a online store ( Europe ) with cheap rack enclosures?

Thanks!

Hi! After owning the Lowthers for a decade or so, the foam surrounds starts to disintegrate. Checked with Lowther Uk to do a renovation, but the prices comes awfully close to a new pair (900€ or 1070$) when including VAT, shipping. Possibly the brexit situation makes it even worse.
So, before making a decision, are there any good drop in drivers (or with minor modifications) available? High sensitivity is a must, they are mounted in a BLH driven by a Firstwatt F3.

Thanks // John

(Edit: I should mention that the enclosure is the Lowther Alerion, a very small speaker, for beeing a Lowther horn, that is �&#56898😉

I decided to try making a simple electret microphone preamplifier for a PC headset, and found a design on GreatScott's YouTube channel here:
Login to view embedded media
I soldered it on perfboard, and it works well except I get a constant "rushing" sound, not hum, on the output. It's quite loud, not just a low background noise. Things I've tried so far are reducing the gain-setting resistor R2 and R5 values while keeping the gain similar (around 22), and increasing the power voltage to 12V since 5V is low for a 5532 / 5534 (the rushing sound increased with power voltage).

Does anyone know what could be causing this noise?

A screen grab of the circuit:

Moving on from a sealed fullrange line array made with SB65WBAC25-4 times 36 floor to ceiling is my next project. I like the current line array system, but I also like my 3-way open baffle and horn system so what to do? Full length 3-way open baffle of course!

Goals:
- Single driver from 400hz to above 7khz. (I think) one the things I find pleasing from the horn and existing OB system is radiation pattern control in that range. See Geddes. Also Linkwitz took his system from about 1khz to 7khz with a single 4" driver with a focus on radiation pattern. I'd like to push that down a bit with the Line Array application.

- I like the sound of Open Baffle bass! In my room it works and I don't have space for multi subs. I've had 4 sealed sources in my room and it works to smooth out low frequency modes; however, I don't like the room pressurization with sealed subs. Something about the presentation is slightly different. Since I don't listen loud and prefer low volume listening I've found the presentation of OB from 30hz to 500hz more pleasing.

- Floor to ceiling straight array. Trying to follow Jim Griffins white paper but will not be implementing shading at this time.

- Minimal baffle width. Trying to follow Linkwitz and John K. philosophies for baffle width. Trying to stay below the baffle peak in all drivers is difficult. Some compromise are in order of course.

- One thing I wanted to try is a space between the midrange and woofer line in hopes to get some horizontal OB control with minimal baffle. Not sure how to perform accurate measurements for this in room. Would be nice to get some side cancellation so the midrange line doesn't "see" the woofer baffle as support. Not sure this will be feasible. According to Jim Griffin white paper spacing should be less than 1/2 a wavelength. I think we can get close to 1/4 wavelength at crossover but I'm oscillating on the woofer array right now.

Tweeter Array:
Dayton PTMini-6. 24 high.
Since they are sealed will have to make the array with front and rear facing units. That doubles the cost of the tweeter array so we will make a front firing array first and see about the full monty later. The nice thing about these drivers and this application is the driver width = 23mm. So a full dipole line array could be constructed in a 1" by 1.5" package including all wiring. That is mechanically very nice. This also allows a type of plug and play tweeter array to use with my existing LA for sport. Also in theory the radiation pattern should be nice, although since we are using side mounted midrange we might not be able to take full advantage of the radiation pattern 🙁.

Construction will be done using 1/2" baltic birch with tweeter mounted using double sided sticky tape from home depot. This worked out well on the test baffle. Simply drill holes for the wires/quick connects and go one your way. Allows for nice spacing with minimal effort. Also one can pre-assemble the wiring harness for 6 in parallel and 4 in series. Making roughly a 4 ohm load. Can gain a bit of sensitivity that way. Construction will not be as excruciating this way and might get some damping due to the tape soft mount. Ceiling mount so they don't fall over.

Midrange Array:
NEO8-PDR times 10.
I know not really exciting here but it really is one of the best choices for this application. Will have to go with 2 in parallel and 5 series. This looses some sensitivity but no choice here. Cannot fit 12 in my room.

Construction will be done with 1/2" by 1/2" aluminum square bars. This allows for minimal baffle and hopefully enough strength to stay somewhat straight! Foam damping behind the driver and routed out depressions for the NEO8 rivets in the back. This will be a lot of work for me but not too bad. Probably need a hole template. Ceiling mount so they don't fall over.

Woofer Array:
TBD.
Would be nice to stay with 1/4 wavelength at XOVER and use 10" drivers times 8. That said I haven't really liked the any 10" OB drivers I liked for bottom support. Thinking 15PR400 would be something but no minimal baffle then and CTC spacing is a bit much. Some thinking to do........taking suggestions. I like the low QTS professional woofers with EQ better than the high QTS drivers I've tried. That said the GW-1858 was nice but missing the clarity of the 15TBX100 I used. I was using the GW up to 500hz so in this application the lower QTS sounded better. If low bass under 100hz, probably no difference. Since we are looking at 350hz to 400hz XOVER we should be careful about this or perhaps some major disappointment and expense.

More to come later. Tweeter and Midrange drivers on order!

Hey guys I have a power 1051s on the bench. One channel has different voltages per fets. N channel side has 78V from pins left to right while P channel side has 50V and 48v from pins left to right. All outputs checked out fine none had short. All emitter resistors are in tolerance. Not sure what’s going on with this one. This is the left channel. Any tips appreciated thanks guys!

I only found few 5 watt class d amps that will power off 5v regular USB. But higher power amplifiers need 9v+. I am looking for around 20w per channel+40-50watt for subwoofer in 2.1 set up

I am building a pair of speakers and ideally want to eliminate all the wiring.

At the moment I have 2 speakers. One speaker will have a Ryobi battery and charger , amplifier and speaker drivers.

Was hoping to make things a little more delicate and integrate battery pack than can be charged with usbc..

Charging is no problem but how do I extract 12-18v put of the power pack. How to facilitate stable 12,18 or 20v DC current out of power pack to power the class d amplifier.

I'm planning my next project which is to implement 3 digital filters to drive a 3 way speaker without crossovers, in effect simulating Linn Aktiv but digitally instead of using analogue filters.

The digital filtering is to be done on one or more Raspberry Pi pico devices, circa £5 each.
These have a 32 bit cpu running at 133

The rough idea so far is to have one pico supplied with s/pdif from a cd player/transport and split it into 2 parallel data streams for left and right channels.

Then there will be 6 more picos, 3 for each channel to perform LF, mid, and HF filtering. The output from each, probably converted back to s/pdif, feeding a DAC (6 of).

I need to investigate filtering algorithms but a rough estimate for a 44.1 kHz 16 bit data stream, a 133MHz pico be able to perform 1500 instructions (assuming 2 cycles per instructions, most instructions take 1 cycles) so I'd have thought that is more than enough.

Has something like this been done before?

I'm looking for C source for decoding the s/pdif signal and for performing filtering on a data stream.

Note this is purely for fun to see if I can do it so not intending it to be a commercial product.

as above.

When it previously worked (2 weeks ago and on different batch of transistors), the measurements are in the 3-5mA range.

Things I've tried

• I've wired the circuit in a breadboard and rechecked the connections using the meter's continuity function. The circuit is simple enough, I don't expect to make any mistake.
• Vbe reading is around 0.5volts
• I tried 2 meters using the uA/mA terminal and the uA and mA function selection (my meter has separate uA/mA/A rotary selector)
• I tried a previously BC550 where I successfully measure the hFE previously and in this instance, I'm not getting the current collector current.
• I don't have a 9V battery but I used a 15V SMPS and an adjustable regulated supply (using LM3X7 part)
• I just bought 10-15 BC550 from the local electronic hobby shop and not getting any measurement.
• I tried 1M and 1.5M resistors (1M + 2x 1M in parallel). I checked the resistor values using a meter.
• I found an article on the web that says I can use the meter's diode test to see if the transistor is working. I've measured around 0.7volts from base-to-emitter and around the asme voltage from base-to-colletor.

Any ideas what I could be doing wrong? Thanks

this is the circuit I'm using

I ask for help this time to find the values of the R7 and R25 resistors, if someone has the amplifier and I could give me the information I would be very grateful, the problem consists that the IRS2092S does not start and I dont see the resistance that gives reference

So I started thinking about melding old and new technology today and started wondering why we don't use pre-distortion more in home audio. Has anyone played with this before? If we were to measure a tube amplifier's THD, phase, frequency response, etc. couldn't we create an inverse filter which would improve the performance of the amplifier? Could this work to replace negative feedback in our amplifiers for that "zero negative feedback" sound without any of the drawbacks? Could this be taken a step further to measure an amps performance when connected to a particular set of speakers so that you take into account the complex interactions between the speaker and the amplifier?

Who can answer or where can I get information on what the events in the attached list actually represent and how the default voice tones actually sound?

I'm planning to build a retro high-fi cabinet, and I'm looking for candidate speaker designs. I was thinking of building space on each side of the cabinet to house a speaker, instead of permanently building the speaker into the cabinet, but that's just an idea. I understand there are several reasons why this isn't a recipe for hi-fidelity, but I'm willing to live with the compromises. I have an SHD Studio on-hand that hopefully I can use to smooth out the gross issues.

Anyways, do you have any suggested designs to use? The ideal candidate would be compact, to keep the furniture size reasonable. I'm kicking around the idea of running a small sub too (separate enclosure). The intended use is for casual listening and TV.

I am planning on building an 845 amp. I was considering a power supply just for the 845 and a separate PS for the input driver stage. The 845 will be IT coupled to the driver.

I was wondering what the feasibility is of building the 845 and power supply in its own chassis and the input/driver with its own supply in another chassis. I was thinking of lockable din plugs and sockets. (I would think no more than 1/2m of interconnect.) Would there be any issues of the IT being that far? Or any other issues.

I've been thinking about it because I thought it would be an easy way in the future for experimentation. For example, I can change the 845 OPs or try another configuration with the driver without having to go through all the circuit. (I can't play an unsecured breadboard as I have a kid around.). Thanks.

Hi everyone,

Would someone be kind enough to help me,

I am replacing the 8 inch drivers in my dynaudio profile 3 speakers ( Driver 21W54 ) with the SB23NRXS45-8
They mate to a Dynaudio D54AF dome midrange
The crossover network as all first order with the inductor to the bass driver 1.8 MH Crossover point 700 HZ
I obviously need to keep that inductor and crossover point for integration to the midrange.
The original bass driver had no cone breakup filter on it but my question is the new replacement SB23NRXS45-8 driver will .
The cone breakup un the graph looks to be between 1000HZ to 4000 HZ
Can someone please point me in the right direction to calculate a notch filter for this driver.

Regards

Hi, I found a bunch of these transistors, namely BD334 and BD333 , but I see I can also purchase the other variants easily.
Are there any interesting amplifiers made with these darlington transistors? I have some headphones id like to make an amplifier for (8ohm and 120ohm over-ear models).

Hello everyone. I have a chance to purchase the cabinets in the picture. No speakers. Are they useful?
I am currently in the process of building a lascala bass bin and have not yet built it.
Maybe it's better to buy only some of the cabinets?

This is just me having too much fun with TINA-TI simulator 🙂




I don't know if it will work in the real world (might build it just to tinker around)

In the schematics I am using LM4562 and LM3886 as composite amplifier. That usage probably has problems since I don't know much about composite amplifiers.

What I am curious about is that LM4562 OPAMP used not only as a part of a composite amplifier, but also as a differential amplifier for balanced input signals from the previous stage.

Any comments are appreciated!

Attached is the simulation file and screenshots for frequency and phase response.

PS: I am aware that @tomchr has built excellent composite amps and I am considering building one of those in the future. But for now I am just having fun tinkering with the design concepts...

Hello,

I need a few heatsinks for the Toshiba jfets(to92) that EUVL some years ago. I am interested about type 0(4 or 8pcs) or type 11(2 or 4pcs).

Thanks.

Hello,

Long time lurker—just dipping my toes into Icepower and audio in general.

Hum and low volume on a 200asc using a Ghent chassis. I checked all the solder joints for continuity and the board is receiving proper power. Here is a picture of what I'm working with. I followed the wiring diagram in the documentation.

Hey
When I powered up my 300b monoblocks I saw my full range drivers twitch, just moving without any input.
Just noticed this for the first time today.
I always turn the amps on last and off first. What’s the likely cause?
Thanks

Hello everyone, I am from Indonesia and newbie to DIY audio enthusiast, actually vacum for around 25 years after working as an employee.
Now just retired, looks like there are challenging in design of Transmission Line box with full range driver especially SB Acoustic produced in Surabaya, Indonesia has launched SB Acoustic SB20FRPC30-8 8 inch.

Is there any software running in Mac OS, using Macbook Air M2 to design & test Transmission Line box and what kind tools supporting?
Or anybody has built Transmission Line box with this driver, any link video test sound?

I have its detail specification from factory.

Thank you everyone.

Mods: I don't *think* this violates any rules but if it does and needs to be removed, please let me know how I can still share this info since I think many here will be interested in it.

Many of you know that I used to do speaker/driver testing for a number of years for DIYMA before moving on to creating my own site (medleysmusings). If you have no idea what that is, it’s a site I used to post objective data to and share with the community. It was focused on providing Klippel data, frequency response (on and off-axis) as well as THD and a few other things along with analysis for various speaker drive units. I took the last couple years off due to personal reasons. But I'm gearing back up to do something big, at least for me. I’ve been itching to change things up and move my review format to YouTube and also expand out of raw driver testing and instead provide a wider range of information. So, that's what I'm doing.

The core of my efforts will focus on product reviews and tutorials (i.e., how to use a DSP, how to tune, what to listen for, etc) along with some other miscellaneous things. I will continue to provide objective data when I can/where it makes sense and I plan to do that as a supplement to the YouTube format; providing the data via a new website. I have a long list of ideas that I’ve collected over years. I think I have a few ideas for my reviews you all will really dig.

I have created a Facebook Group page for those who want to follow it. This page will be a way for me to update everyone on progress I make toward completing reviews. If I get a new piece of hardware to test I’ll share it. Links will be posted to reviews. That sort of stuff. It’ll be an extension of my YouTube review page because, frankly, it’s easier to support conversation here than it is on YouTube. Here’s the link: Log into Facebook | Facebook

To be entirely transparent, I hope to be ad-driven at some point and also do some affiliate marketing (i.e., Amazon, Parts-Express, etc) so I can use some of the advertising revenue toward purchasing new test equipment and products to test/review. I don’t see me ever actually making money; breaking even would be nice. I’ve already sunk nearly a grand in to what I need to get going. In order to get to the point where I can monetize videos through YouTube, however, I’ll need to hit 1k subscribers, and some crazy number of hours viewed per month. So, I ask you all, if you are interested in any of the stuff I’ve done and the past or you just want to support what I’m doing, go ahead to my YouTube page and click the subscribe button. I don’t have anything out there at this moment in the way of reviews but I’m already working on some really, really cool stuff. And if you are interested in the items I review in the future, feel free to click any links I provide to my affiliate advertisers so I can get a small percentage of the purchase fee (hey, you were gonna buy it anyway). All that helps me keep this thing rolling and keep me from going in debt in the process.

Here’s a link to my YouTube page:
YouTube

And that’s it… I just ask you to bear with me. I’m not a video editor so I don’t expect to knock this stuff out of the park my first few attempts. But over time, with your feedback, I will hopefully improve the final product and provide an entertaining and educational set of videos. 🙂

Thanks,

Erin

I've wanted to build an amplifier for quite a while. Initially from the guitar amplifier side, and more recently from a hifi perspective. As I look around, I feel like it should be easier than it is to find something meeting my needs, but I keep coming up empty. I want to build an all tube (including power supply) RIAA phono preamp. I want to use all readily available and currently produced tubes. Coming from the guitar amplifier perspective, to me this mostly means 12AX7/5U4, but I'm not 100% aware of everything in current production. I just know I can hop on down to GC, and pick up those tubes brand new and reasonable quality all day long. Call it future proofing.

Can anyone point me in the direction of a schematic or set of schematics from wall to input to output for such an amplifier? Thanks.

Hi guys,
I would like to ask, has any of you expierence from balancing tubes by adjusting the g2 voltage?
If so, would you please share what you found out?
I searched the forum and the net but was unable to find anything related.
Thanks
Pete

Driver : MarkAudio MAOP11(6" Full-range)
Box : HB-15F
Size : W.224 x H.450 x D.300(mm)
Chamber Volume : 17.5L
Duct Tuning : 73Hz









MAOP11 sound at YouTube
Diana Krall by MAOP11　(Recorded at 2.5 meter) - YouTube

Looking for a pair of LL1623 5.6k 60ma Single Ended output traffos.. Need immediately.

text me 541-231-2297 or email jeffwagner@daraceo.com

Hi, I designed and built these fantastic sockets, in PTFE, for my EL3N amplifier, my job consists in making precision prototypes for the most varied industrial sectors, so I decided to make them available to all passionate DIYers like me , there are unfortunately several hours of work, with these but the quality justifies the effort.
I'm selling them for 95 euro cad.

Maurizio
e mail. maurimauricap@ gmail.com from Italy

I just finished an EL84 push-pull amplifier using Electro-Harmonix (EL84EH) tubes. I'm running 300V B+ and a shared bypassed 110 Ohms cathode resistor. Each EL84 also has it's own 2 Ohm (unbypassed) cathode resistor to measure bias current, and I'm using a 10 Ohm potentiometer to adjust the bias balance between the two tubes. Total, each EL84 has 117 Ohms cathode resistance.

This results in about 47mA bias current per tube, making the plate dissipation around 13.5 Watts. This is a little higher than the rated 12W.

Are the EL84EH capable of this plate dissipation, or should I adjust the plate current down a little bit (i.e. 43mA)?

I have an "Opus" amp on the operating table with a broken mosfet. It is an Exicon 10P20 (10a 200v TO3 package). I have 10P16 (not enough volts) and 20P20 (too many amps) in stock and hoardes of Hitachi J56/K176 which DONT play nice with Exicons (they need to have the same amount of oar in the water as 5 others). Anyone know where I can find the (no longer made) Exicons?.

Hello all,

I "upgraded" two quad opamps in a simple 4 channel synth mixer.
TL074c= out
AD8513 = in
(soic)

AD8513 datasheet.....LINK

I then checked for stability on my scope. I did not see "ringing" but did see "overshoot" at the transients, generally under 2kHz. Over 5kHz, they mostly even-out.
Here are two screenshots about 1kHz.
Yellow = source
Green = mixer output
(I made green's gain is a little higher for visual clarity)



Second one is the same, just zoomed-in.
Gain pot is around typical listening level, no load. Cables are short.

Here is the Mixer schematic...... https://github.com/pingdynasty/Mix/blob/master/hardware/LinearMixerRev04-schematic.pdf
Notes:
There is no overshoot out of the first-stage quad opamp, only out of the second quad opamp, at the output....before (or after) the 1k ohm output resistor.
I tried putting a snubber network on one output, as suggested by the AD8513 datasheet, with no affect at all.
I also added 0.1uf psu bypass caps on the affected quad opamp, before testing, as a precaution.
I added some 4 foot length cables to the output just to see what would happen.....no effect/difference.

Frankly, it "sounds" fine. Should I even worry about this ?

Just a quick idea that came to my mind this evening. A couple of weeks ago I was using a cheap piezo disc, recycled from a broken smoke detector, to try and generate some ultrasonics up to 100kHz. The reason was to test a 1/4" microphone capsule with a quickly hacked together mic preamp for their suitability to capture the sounds of bats. I'm not quite satisfied with the results yet, but it kinda sorta worked okay for a first test. Of course there's a hen and egg problem here, since I neither know the frequency response of the mic, nor the piezo disc. The response was quite rough, but I was totally able to get up to the 96kHz recording limit of my sound card with no effort.

So now I thought about what might happen if I use this piezo disc instead of a vinyl test record, place the needle on top of it, and play a frequency sweep.

The piezo disc was connected directly to the output of the soundcard (a Scarlett 2i2) and excited full steam with -3dBFS output from Room Equation Wizard. The phono output went through a diy RIAA preamp connected back to the soundcard input and the following response recorded:



Looks pretty rough, but the part between 18k - 28k is somewhat interesting. It seems to suggest a useable response up to 23kHz without an early peek or drop.
My quick'n'dirty test setup is certainly far from ideal, but maybe there's some potential to achieve some better results? The main reason here would be to observe the range from 15k - 25k to fine tune the input capacitance of the preamp.

Looking for suggestions on the schematics that I came up with. Everything was based on the datasheet (almost).

I am anticipating each LM338 to produce [(35V-32V)*8A]/2 = 24W/2 = 12W of heat.

I found this heatsink here by Ohmite - https://www.mouser.com/ProductDetail/588-FA-T220-64E - hopefully this will be enough if I mount each regulator on its own heatsink.

I am also wondering what that 1uF el capacitor at the input is doing? Can I replace that with bigger capacitance one (10uF or 47uF)?




Here is what datasheet suggests:





Any suggestions and help are appreciated!!

Gents, I have an interesting scenario I'd like to run past you - I purchased a nicer silver conductor XLR cable a while ago, but here is the thing: The pin-2/+ Conductor is a beautiful solid core silver, but the cable itself is constructed with this one silver conductor with the other two comprising of 2 separate layers of silver plated braided sleeve. Pin-3/- is a conductor of lesser quality - with GND being fine, whatever.

With most equipment being differential, what might I be losing with a lesser quality conductor on the negative path? I was thinking of changing cables to one which has both pins 2&3 solid core silver, but in a differential setup internally within the components, would it matter?

Much of this is based on the clear audible differences and improvements from silver conductors to that of other material.

Thoughts?

Hello. I was wondering if anyone had documentation on summation of HF sources through short horns? Looking at the EAW Anya and similar HF arrays, they appear to be using several HF drivers stacked together with short conical horns instead of the typical line array waveguides.

When sources are within 1/4 wavelength or shorter they tend to sum more cohesively, right? But is that at the source or at the exit of a horn for the distance? It would appear that the Anya uses several short and slightly bent horns. I'm wondering if anyone has tried something similar. It would appear that the Anya has very little or no verticality in the horns and that every other one shifts horizontally as they are stacked.

I was wondering if it is better to just use two LM317 instead and connect them in parallel to LM338 instead of in series like it is in the attached schematics?

R5 and R6 values are to be determined. I might add a trim pot to fine tune it.

Any help is appreciated!

Hi guys,

Maybe someone can drop me a hint to a solution on the following issue. Sound level from my Denon PMA QS10 mk 2 is not stable. Volume drops and rises again but it is hard to put a finger on when this occurs exactly. Quite anoying it is. Most of the time sound quality remains good but sometimes serious distortion can be heard when such a drop occurs, especially when it comes down from a higher soundlevel. It looks it is more sensative for this behavior at low volumes. Then also, more drops follow one after another. The amp has all new and original UHC-MOS components done by a professional technician. Have tried several loudspeaker arrangements, currently B&W 801-S3 (with refurbished tweeters, aka new ferro fluid added) in series with OLS (Kharma nowadays) with Van Den Hull cables. Tried all possible settings too, amp warm or cold, sound direct on/off etc. Amp too good to put on a shelf and make it a museum piece. Anyone idea's? Much appreciated, thanks for your time anyway. Best regards, Jan (Belgium)

I bought some vishay dale wirewound resistors and discover that their leads are attracted to my screw driver. I think the leads are likely to be some alloy instead of copper.

I am wonder if its an issue, I am using them as output resistors for my amp.

Thank you for the help!!

When buying parts for boards, BOMs will indicate specs for caps, resistors, etc. My question is: Are those specs meant to indicate the exact specs that should be bought, or are they mean to set out minimums?

For example: In a BOM i am working on ordering parts for, the values for the Caps are listed as 120u/25V.

The capacitance is 120u. Does that mean ONLY 120u, or is that a minimum?
25V -- is that ONLY buy a 25V cap, or does that mean 25V is the minimum?

Another example:
resistor spec is: .25W Film, 4.99K

Does that 4.99K value mean ONLY buy 4.99K resistors, or is there a range from that that is acceptable?

I am early going in this (obviously) and i have always assumed these specs meant ONLY. But I see discussions where people are talking about variations pretty freely, and so it makes me think that the specs are looser than might otherwise appear.

Bones
Lincoln, Nebraska

Record breaking. Shattering!

Spinning a Record to Pieces at 12,500fps - The Slow Mo Guys​

Two goofballs put LPs on a vacuum-cleaner motor (10,000++RPM) and film it with a very high speed camera.

They also do CDs and plate-glass.

8 pcs TUBE SOCKET for 6C33C PLK7-collect NEW (one of the best for 6C33C)

want 18€/pcs + shipping

The Eminence Lab12 has proven itself worthy in a variety of low-tuned PA applications. This venerable driver has held up well and is still a good candidate for many types subwoofer designs.

The Lab12 has been been around for a while and had been used in bass reflex, tapped horn, and front loaded horn alignments, so I propose a shoot-out of some of these Lab12 designs. Let's not get nasty. What is ideal for one person might not work for another, so please keep an open mind.

One of DIYaudio.com's elder statesmen, weltersys, has two proven designs that I submit for the first-round smack down.



In one corner we have the weltersys Keystone Sub, a tapped horn that is very adaptable:

http://www.diyaudio.com/forums/subwoofers/185588-keystone-sub-using-18-15-12-inch-speakers.html

They Keystone Sub is a big fella (45" tall x 26.5" wide x 22.5" deep), but loaded with two Lab12's goes low and LOUD. This is the grey race on the graph below.




In the other corner we have the weltersys Dual Lab12 bass reflex design:

FREE SUB PLAN: Dual Lab12 (Front Loaded) by Welter Systems

The Dual Lab12 is tiny little fella (22.5" high x 26.5" wide x 22.5" deep) - half the size of the Keystone Sub. It goes just as low as the Keystone, but not as loud. This is the blue trace on the graph below.




So, if you needed a subwoofer that went really low and load, which of these designs would you build, and WHY? What are the pro's/con's you see of each design.

Let's keep things civil. I personally think these are both excellent designs - one of my biggest arguments would be size and portability.

SOLD NO LONGER AVAILABLE


I bought this complete kit and the great I2SoverUSB v.III interface and have decided I will never build this. Free US shipping, contact me for OUS.

Buffalo-IIIsePro38 Complete Kit Combo w Transformers
[1] Buffalo-IIIsePro38 2-Channel DAC w/Full Series Regulator Set
[1] Centaur 2A Power Supply Complete Kit
[1] Mercury Balanced I/V Stage v1.1 Kit
[1] Placid HD BP Power Supply Kit
[1] 9V+9V (30VA) Power Transformer
[1] 15V+15V (50VA) Power Transformer

Also I2SoverUSB v.III (see attached )
XMOS XU208 processor, USB update
Sampling frequencies: 44.1kHz, 48kHz, 88.2kHz, 96kHz, 176.4kHz, 192kHz,
352.8kHz, 384kHz, 705.6kHz and 768kHz
16-, 24- and 32-bit resolution
DSD64 - DSD512

Is there any confirmation that the U.K. is now supplying 230v or is it still at 240v?

I thought that some years ago it was going to be dropped down to 230v with a tolerance of +10% -6% ?

So the 230v could be 230v + 23 = 253v

or 230v - 13.8v = 216.2v

Hello folks.

As many of you know I am working on a killer USB board and one of its features will be LVDS output of the PCM signals.

Well to support that I needed to test that it would actually work at the very high frequencies I was using. Well I am happy to report it absolutely does work, and extremely well!

In the process I created a little module that is also useful for many other applications. That module is call "Teleporter" and here is what it does:

• It is a LVDS transceiver. It works in LVDS mode1 and mode 2. The LVDS channels are properly terminated.
• It has both a .1" header and RJ45(for CAT5) connector.
• It has an on-board low noise LT1763 regulator.
• It has 4 independent LVDS transceiver channels that can each be configured as a transmitter or receiver.
• Each channel either has TTL input (in transmit mode) or TTL output (in receive) mode.

You use two(or more) of these modules for a complete application. One at the source and one at the DAC or some other receiving device. They are designed to be panel mounted using 90deg tabs on the PCB. We will probably proved some with the kit.

NOTE: Please install (or short with solder) J1 for normal (type 1) operation where two teleporters are used as transmitter and receiver. Omitting J1 allows for type-2 receiver mode.
See section 3.2.3 here:

http://www.ti.com/lit/an/slla108a/slla108a.pdf

Here is how I have used it so far:

Also if your board has a J2 position - that jumper connects the jack shield to GND. It is recommended to close J2 if you use shielded CAT5/6.

- DSD/PCM output from a modded Denon SACD player to Buffalo III.
- USB audio to Buffalo III. (up to 384khz tested so far with 256fs master clock)

I have tested it carrying a signal up to 100Mhz(master clock) and it worked flawlessly so far. It *should* be able to handle up to 125Mhz, but I have not tested that yet.

We will be making these available very soon. They will be fairly inexpensive but I do not know the price just yet. Brian and I need to work out the costs.

I am listing to an XMOS prototype at the moment with all of the PCM signals including the master clock being fed to the DAC via the interface. 🙂 It sounds awesome. What is more incredible is that I have been using as much at 100ft of CAT5 with absolutely no detectable ill effects.

Now there is an inexpensive and practical solution to moving PCM/I2S/DSD bits around from device to device without SPDIF or having to use expensive HDMI cables (which may not come in the length you need). CAT5 is much easier to work with and make custom lengths.

It also provides isolation in that there is no shared ground wire. You actually could use HDMI cable if you wanted you would just need to build an adapter, but there would be no advantage to doing so.

I routed the CAT5 connector so that the CAT5 twisted pairs are used for each discrete signal. This allows for more ideal noise rejection.

Now I need to beam up some more music. 🙂

Cheers!
Russ

I recently picked up a bunch of those cheap JBL GX1200 drivers for $29 and started doing little projects with them and have scrap. I've wanted to play around with the idea of tactile response and impact with near field subs and also wanted to tinker with open baffle to learn from it and measure it and see what that's all about, satisfying a lot of curiosity for a few coins. I don't know how to model open baffle or free air driver response and behavior, so I just had to build it and see what it did.

Keeping it simple, I started with a wedge that is about 22 degrees with a 30 inch tall back so that both the 12 inch drivers would fire into my chest and guts in my seating in my audio room. I ended up doing 30 inches (back) x 12 inches (base) x 0.63 inches (top) with a 31 inch face at a 22 degree slope. I gave it some braces between the drivers and in the bottom back. I wasn't sure how this would effect things but I know it needed at least some kind of bracing. All glue, no screws.

I rounded the edges and sanded it and then said, well, what the heck, and went ahead and pre-stain, stained (Early American) and then did a top coat of satin poly over this birch veneer ply scrap I have. I'm not going to see it behind a seat, but figured, if I do anything else with it it won't be bare timber.

The drivers are ugly, the red JBL 1000w logo on the dust cap is hideous. I need to find a way to replace those inexpensively. They're $29 drivers so I cannot really complain.

I did some listening first, some music and a few movie scenes. Then I did some measurements, near field on the drivers and at the listening position with room influence. Pretty interesting results.

I wired them in series so they're around 8ohm. I am powering them with a 75 watt RMS at 8ohm Dayton sub plate amp in an outboard box of its own to keep it simple. No DSP. No EQ. At least not for testing at first. It has a built in 18hz high pass filter, and I just let it keep a low pass filter of 120hz or so. Later I tested it on my NX3000 channel to give it more output and was able to max it without ever seeing clipping or signal issues at the amp, so these 250w RMS drivers together can definitely soak up 500 watts no problem. They're both 12mm xmax so together they can move quite a lot.

Overall I like them for their effect for impact and tactile response. I did a crossover in my miniDSP to test them limiting them to 45hz~100hz basically with sharp drop offs so that they're basically mid-bass modules and then maxed the volume on them. It was interesting to have the impact in gunfire scenes in John Wick, Heat, Equilibrium, etc. Lots of thump in my chest from those with this behind the seat. It made me want to re-do this with 4 drivers to get even more.

For just general music listening it surprisingly sounds great. It takes a lot of amp to get them to be loud, but at around 35 watts per driver at 1 meter it was plenty loud for me for music and was capable of digging quite deep. Deeper than I expected. I would need a lot more amp to use them in a larger room and listen at greater distance for sure, but to off set that I would rather use more drivers. That's a future project.



















Here's some measurements. The top two are near field. The upper driver is in red. Really nice response from 30hz to 180hz. The drop at 34hz or so is due to the narrow wings at the top of the baffle. The bottom driver in blue. Same response, however, it has much longer wings next to its baffle and so I get the low end response from 30~34hz back. Learned a lot with just that simple bit on the sides with the baffle. For mid bass this didn't matter. For sub-bass it would matter a lot. When measuring these I referenced at 99db.

The green line is at the listening position with the room involved. Surpringly not bad, it kept bass pretty decent to 30hz. A little EQ and this could be flat. I referenced this at 90db. Ultimately this wasn't meant to do anything at 30hz or over 100hz. I just wanted to see what it would look like with the open baffle. This graph doesn't show it, but I later used a crossover in the miniDSP to set it to basically focus on 45hz to 100hz as a mid-bass slammer module.



Fires into our guts and chest behind the seats.

It's really back heavy with those magnets. It actually leans on carpet. I think I will put some small feet in the back to keep it straight to counter the weight.



Learned a bunch about open baffle with this. Will explore more. Also learned a lot about tactile response and impact. Going to focus more on this now.

Very best,

Hi friends, can anyone help me to choose which transformer to use for Balanced input and unbalanced output for a 27k input impedance amplifier.
Like there are Jensens but any specific model to choose.

This circuit uses the LM431 as an alternative to strings of high voltage zeners. High voltage zeners are subject to drift with temperature.

Hey folks. New here hoping the community can lend a hand.

I have a basic understanding of the audio system(s). I had just installed an audio system in my bike. Upgraded saddlebag lids, put in an amp, upgraded 6.5 fairing speakers and put in 8” hybrids and 2 tweeters in the bags.

I installed the system without the additional tweeters first, adjusted the gains and got a good sound. Then I installed the tweeters and ran them in parallel to the coaxial 8” hybrids. Doing that I got more power to the set but then I blew out one of the hybrids(started distorting and crackling intermittently).

I understand that parallel “halves” the impedance thus making more power available. However I should not be even close to the max handling of the speaker to blow it. I am certainly missing something

The amp is a 4-channel ds18 candy z4b pumping 100rms at 4 ohms and 150 into 2 ohms. Fairing speakers are 2ohms and adjusted nicely. Coaxials AND the tweeters are 4 ohms. Coaxials are rated 250 rms and tweeters 200 rms. There is a 2.8 k crossover installed on the positive lead between the hybrid and the tweeter.

What did I do wrong? Do I need to bring the gain down after installing the tweeter in parallel ?

When measuring low levels of THD or THD+N the recommendation is often to use a notch and LNA.

Here is a measurement at -2dBFS of a AK4493 dac with ES9822PRO. Without notch.



I get similar results with another ES9822PRO ADC so this is not device dependent. And just to show that this is not some heavy distortion cancellation here is the same setup but with at 2567Hz -3dBFS.



So very similar result.

Now let's use a -30dB notch + LNA (CosmosAPU). But before that here is a measurement without notch but at -32dBFS level.



Third harmonic is now clearly dominating over 2nd. Hard to tell if this is due to DAC or ADC.

And finally a measurement at -2dBFS using Cosmos APU +6dB with compensation.



The harmonic profile is very similar to previous measurement at -32dBFS.

Now the question: compared to the first measurement without notch why would this notch measurement be considered more accurate?

I just wanted to share some things I found today while playing around. I recently bought a connexelectronics 48V SMPS500R-single to power a Pass Zen v1 amp that I have. Unfortunately when i tried the SMPS on the amp my outputs shorted internally(I am still not sure what happened) so no more Zen V1 until I figgure out the issue.

Today I decided to try my SMPS on a JLH 69 amplifier I assembled using MJ15003 outputs and an unregulated linear supply. With the linear supply the amp sounded good but it never sounded like something special. It was easily bested by my Decware Zen select when A/Bed on multiple occasions. It also always had a slight hum on my parker audio 98s (96db/watt/m) but you couldn't hear it from the listening position.

With the SMPS I had no hum and no noise from the speakers and it sounded better in every way. The soundstage was bigger, the sound was clearer (less veiled) and the bass was improved. The amp now sounds like a real high end amp to me. I have not A/Bed it with the Decware Zen select but if I were to make a guess I would bet they are now close to the same level but just different "flavors". I think I may order another smps with the proper voltage for my JLH and make this a permanent addition.

BTW i tried adding a 1mh coil between the smps and the JLH to clean up any noise from the smps. I previously tested this unloaded and the coil did lower the noise output on the smps. I found however that this had a negative impact on the sound of the amp. The bass seemed to be reduced and it gave the amp an overly forward sound. If I were to play with this again it would be with an inductor made of a much higher gauge wire. Honestly I really don't think it is needed.

I put this up so that any of you who still think SMPS is not for hifi. I think the technology is here and could be used to push some current amplifier designs even further. If you haven't played around with SMPS I suggest you give it a try.

Hello,

My usual warning: I am learning. I have much to learn. I will often ask stupid questions and reach incorrect conclusions. Thank you for any education you may give me.

I am trying to learn more about tube amplifier circuits by reading and dissecting examples.

Case in point:



I already peppered this one with questions (A, B, C).

I also assume that only capacitors at 1 and 2 would affect frequency response. Am I correct?

I still have much to learn about picking proper operating points for the tubes themselves. I am not sure if the values shown on this drawing are anywhere near correct. But I suspect they may be odd or wrong. (but it's probably just me and my ignorance)
But in that regards, how can this design be compatible with all of 12AT7, 12AX7 and 12AU7?

Finally, do you know of any reference that would inventory circuit patterns found in tube amplifier designs? I have not been doing this for very long, but I think there are quite a few pieces that appear in many designs and it would be O so wonderful if they were catalogued and explained somewhere.

Again, thank you for any help and sorry for the stupid questions.

Who can answer or where can I get information on what the events in the attached list actually represent and how the default voice tones actually sound?

Hi everyone,

I recently looked at the small powered sub from Fostex that uses a 200mm driver and was wondering if there were any designs using even smaller drivers?

I know the (sorry to use the 'B' word) Bose Acoustimass literature says it uses 3 smallish 5.25" drivers in a seventh-order band-pass config (3 chambers + x-over?)

Are there any known designs that use a 4 or 5 inch driver(s) in a small cabinet to give sub-woofery-type noises?

I have access to a CNC router, so cutting fiddly bits isn't an issue.

For all I know, small drivers and subwoofer may be competely incompatible,

but I thought I would ask.

Any help will be appreciated.

Hi there,

I want to build a multiway speaker. The loudspeaker should get a spherical plastic housing (approx. 50cm diameter). Which high-quality plastic is best suited for this and how do you calculate the thickness of Cabinet?

Not sure if this is the right place to post but has anyone actually tried the SIDEGIG-GUITAREVM from Texas Instruments?

Here is the evaluation board
http://www.ti.com/tool/SIDEGIG-GUITAREVM

And it plugs into the TPA3255 Class-D amlifer
http://www.ti.com/tool/tpa3255evm

I am wanting to build a Bass amplifier and want to base my whole design around the TPA3255 amp and use the SIDEGIG design as my preamp and overdrive circuit but I am worried it might not sound as good as I want it to.

Has anyone tried it out yet?
If I posted in the wrong section please let me know where I should post...

If anyone's ever been curious what ATI is putting into their amplifiers, here is a schematic I found. Generally speaking, their schematics do not seem to have been published. For those who aren't familiar with ATI, ATI is a fairly large US-based amplifier manufacturer that has not outsourced everything to China. They have OEMed products for a number of companies, although for the most part they don't admit whose products they make. Their calling card, though, is individual amplifier modules and you can usually tell their products from the back panel.

To be fair, this schematic is actually for the Earthquake Cinenova Grande circa 2014. They were kind enough to post it on their European website (by accident?). The amp is clearly an ATI. The original versions had the same goofy parallel port connector ATI introduced (and which went nowhere), the modules use the same heatsink as the ATI AT2505, the topology is a complementary diff which ATI is known to use, and so forth. Whether ATI still uses this exact circuit in their house branded products, I don't know. I suspect in lower priced OEM gear like the Monoprice Monolith they do (less a few output devices). Their new high end stuff is a fully balanced design, so is different.

This is a fairly simple design complementary differential input design, without a whole lot of tricks up its sleeve. It is what it is and perhaps someone will find it useful if they're trying to fix one. Or are curious how a particular design performs. (Bench tests at Product Review). I suppose they had to keep the parts count down to fit it all on the module? Who knows. There is a lot that could have been done here that was not. My guess is that this is close to the same thing (or even less sophisticated) than what Jim Bongiorno designed for SAE more than 40 years ago (which was owned by the same people as ATI).

Hi guys, is it possible to get 60W of power output from a pair of 6C33C? I see some designs getting 40W out from pushpull Class A. How about Class AB 6C33C with more of power output? Can anyone recommend bias point?

I'm also looking at EL509 triode mode which has Rp of 200 ohm. It may be a good alternative to 6C33C class AB because of its high peak current?

Thanks in advance for your suggestion. 🙂

I want to buy a Pair of Tang Band 8" Fullrange Drivers Model # W8-1772.

I can pay via PayPal

Hi all,

I custom built an 8 channel amplifier made from 4 separate TPA3255 dual channel amplifiers with a microcontroller coordinating their reset based on time and the input voltage levels. They all exhibit the same issue.

The issue is, when I first turn the amplifier on and it's at room temperature, the TPA3255 will be brought out of reset after the the microcontroller has seen the power supplies have settled (12V and PVDD) then the microcontroller will connect the speakers through the output relay. Now, everything will be fine for approximately 3-5 seconds when the TPA will go into fault mode (FAULT -> 0 and CLIP_OTW -> 1). The microcontroller then disconnects the amplifier by turning off the relays, puts the TPA3255 into reset, waits 1s, brings the TPA3255 out of reset then connects the speakers via the relay once again. Now the cycle repeats for about 10mins until the heatsinks are a little warm to the touch.

Could anyone suggest why the TPA3255s might be behaving this way? Attached is my schematic.

Many thanks,
Boscoe

For sale pair of tweeter and midbass,used but good condition,taken out from Royd audio Apex speakers.Price for all 4 units 60 euro plus 15-20eu shipping inside europe.If interest plese contact me.Paying thru paypal.

There’s the ESS hump
then AKM is trying to get back on its feet and is considered soft sounding.…..


why don’t DAC manufacturers use other chipsets like Cirrus or TI or something else?

i don’t get it.


out of a bunch of DACs I tried. The Topping D30pro which uses the newest Cirrus chip sounded most natural. Lacked weight and punch, but I think that was just toppings fault at a sh$$ty implementation.


so why all the fuss around ESS and AKM when nothing new in DACs which use these sounds so good?


cheers

As some people here may know, I have designed some remote control boards.

So far I have a small board for controlling a motorized pot, and two different boards for "passive preamps". A lot more will be added, when I have to time to get it finished 😉

You can read about them here: http://electronics.dantimax.dk/

And you can read some of the background info on my personal website.

Best regards,

Mikkel C. Simonsen

I have a FR 8" Diatone alnico driver in a 1cu ft enclosure which is ported. I like it, but bass is lacking. I was thinking of installing a 8" woofer to the rear of the cabinet and running it so I get a push-pull effect. I would have to attach it to the outside on the back, and face it towards the front speaker ( not enough depth to put it inside). Anyone ever try this? Diatone is 4 ohm...so how to connect...in series?

Hi @All,

I'm looking for 4 x NJM7915FA, please offers via conversation (please including shipping costs to Berlin / Germany).

Many thanks and regards
Carsten

Hi,

I'm looking for a pair of Lundahl LL1668/25ma anode chokes. If you have a pair lying around please PM me.

Thanks,

JBL 2235H.

The only equivalent (possibly superior) driver I have come across is the AE TD15H.

This driver seems to be super versatile. High sensitivity, low Fs. Good for subwoofer, two way (crossed over to a CD-Waveguide), three way, Hi-Fi, HT, SET amps... what have you...

I wonder why nobody is making such a driver now, other than Acoustic Elegance. Or am I missing something?

Hello,

I have for sale 2 stereo pcbs done after the article in the title.

https://www.firstwatt.com/pdf/art_sony_vfet_pt2.pdf
Schematic on page 5, only what regards the front end.

I used them as a balanced preamp with very good performance.

I attached a photo of the part that is included on the pcbs.

The pcbs come with all the parts populated except the active parts in the signal path(jfets, bipolars, mosfets).

I have also the low noise power supplies that I used with them.

Sold


EDIT: attached also a thd measurement done with the same power supplies I sell here and the semis I removed.

FS:

hi all, selling for a friend:

2x new choke LL1673, 200mA/10Hy - both 200€ shipping included in EU​

2x new choke LL2742, 90mA/46Hy - both 200€ shipping included in EU​

unused and never mounted, parts got from Jacmusic.com

Hello,

Any schematic available for a Adastra RM1202.
I'm trying to repair this equipment and I'm having a problem with distortion. It would be great if anyone could help with this =) !

Exactly what we needed for a closed box and OB. Redcat Audio SW15.01X8
Price 79€.
85db

95db

https://oaudio.de/REDCATT-SW1501X8