I have a good sized heatsink and it is cooled by a fan - at this point using 38 volts with ra7's TDV. Biased at 2.6 A the heatsinks never get hot, not even close to hot. Nowhere near as hot as the SIT 1s would get which was HOT.

Would higher voltages allow the use of sightly less current - my scheme is to use closer to 55 volts? Even higher if possible. My capacitors are rated 100 volts and higher. I know the current would be greatly reduced just trying to figure out where to begin ... if at all.

Would the output power go up appreciably or would it be negligible?

Wish I could answer this for myself but I have no idea.

It is my first subwoof. Pretty basic, no dsp on the back panel so this must be done upstream of it. My Emotiva PT2 has a sub out with a variable low pass and it seems to work well. It also has a variable high pass on the pre out. I thought it might be hard to get it integrated with my speakers but so far, so good. It does stand up bass and cello nicely which is low enough for me.

Greeting speaker lovers!

I am need of help from the community. I am looking for the original T/H parameters for a VIFA M18SJZ4-04. It came out of a Sony SS-X70ED. Both are drivers are toast in each cabinet. I can normall come up with my own T/H but given they are damage, this is not possible. I have looked everywhere for the data sheet but it eludes me.

Any assistance is welcomed!

Hey forum,

I’m looking to design a speaker specifically for sound healing frequencies.

Since the audio will not be heard, the volume won’t need to change, the only thing that needs to change is the frequency.

With the same excursion the driver could be driven by an electric motor that varies only in speed.

I’m looking for a designer to design this in CAD, I understand that this would require specialised knowledge and isn’t something normal. I will compensate you well if you have the skill set to do this!

If anyone knows any companies I should reach out to, knows any people that build drivers or have any ideas for the project please let me know!

Peace, love and light
Jeremy

I have a pair of relatively cheap 18" woofers. I have used one in a MEH as the bass part for quite a while with open back and I liked it. The new round MEH will not play as low, but I thought I might use these in a sort of bandpass sub, but with open back - like on the large MEH. The Hornresp record is attached. It needs some eq, but compared to a simple H baffle or a bass reflex box of the same dimensions, I get more efficiency and acoustic bandpass filtering as a bonus. It comes with the cost of boosting the low end need and needing more amplifier power and not much output below some 35 Hz. Amplifier is not a problem and it did not play lower in the MEH anyway, so this seems like a good compromise.

The plan is to have a simple 60 x 60 x 66 cm (OD) box serving as a stand for the round MEH. Would any other enclosure style in this volume have some advantages?

I have been looking at a few amplifier schematics recently and noticed two things that seem very common on class AB amps. one is a series inductor on the output, typically 1 or 1.2 uh, sometimes in parallel with a 200 ohm resistor, sometimes not.....and the second is an rc circuit to ground, ,not usual to see like .047 uf cap in series with a 10 ohm resistor to ground?

what are the purpose of these?

I’m thinking of creating over-engineered loudspeakers. They might be something such as the 3.5 ways floor-standing with 4 active drivers and 2 passive drivers, i.e.,

• A 1” tweeter at the top of the front baffle
• A 2” dome midrange below the tweeter
• Two 10” woofers below the mid-dome in which the upper woofer is responsible for lower midrange and bass, and the lower woofer is for only bass
• Two 10” passive radiators for deep bass at the bottom and on both sides of the cabinet, e.g., Acoustic Research AR-9/ AR-90 series.

If compared with a conventional 3-way system, will it be better than the 3-way? Assume all the crossover design is performed with the same techniques, by the same designer.

It’s just like comparing a multi-link suspension with a semi-trailing arm suspension.

Is it worth it?

Excellent condition -$650. Web is full of pictures so no need to waste a band here.

I am selling my entire collection due to extreme hearing loss unfortunately. THD+N (Nick) on AK built me this 300b amp with attention to quality parts and professional build quality. I don't think you will disagree by looking at the pictures. Most of all this amp sound amazing!!! Built with Edcor iron and includes a pair of Shuguang 300B-98. NOS Sylvania 6SL7 GT tubes with 5U4G rectifier.
1850.00 OBO
Will ship at owner's expense.
Pay Pal F&F
Local pick up is always welcome in Clarksville TN
Thanks
Rich

Hello to everyone!
This is my first post here on this forum, and I hope there are going to be many more.

So right to the point:
I have an Adcom GFA-5500 power amp. One of the best I ever had. Sadly, it now looks like one of the main power capacitors have started leaking. So I'm looking for replacements.
I have found some high grade Mundorf ECaps with the same dimensions and the same terminal spacing, rated 22000uF, 100V. The originals are 18000uF.
Is it a bad idea to replace the originals with ones with higher rating? Or is it just good to have more reserves in the power supply. Will it stress other components?

Thanks in advance

Hi

I have a pair of Mission M33i floorstanders here that need replacement mid/bass drivers (amp malfunctioned and died).

The speakers didn't cost me anything and I don't want to spend much on a solution. The usage will be playing loud rock music and EDM in my workshop whilst me and the wife workout in our gym.

I can find the right size (hole spacing & cutout) easily enough.

My question is, the frequency response. The original drivers are 48Hz to 20,000Hz.

The replacements are likely to be ~35Hz to 8,000Hz.

My understanding (from a mate who may or may not know) is that for my intended use, I don't need frequency response much above 8,000Hz, recognising this is not an audiophile kind of setup at all. It just needs to be clear and loud. Overtones, harmonics, headroom etc, not so important (I think).

The specs of the originals can be found here: Mission M33i

The likely replacement can be found here: Possible replacement

I know nothing at all about crossovers and so on... just considering taking a punt.

Any advice gratefully received.

Thanks.

Thanks again for stocking more boards. Is TR1 an IRL or something else? What value/part no. would you recommend?

Cheers, Steve

A little project I've been working on the past few months. I wanted some "ultimate" desktop speakers and with my limited workspace thought 3D printing would be a way to go about it. Still a WIP, but some first impressions...

The drivers are Markaudio Alpair 5.3. I used WinISD to create an EBS3 alignment which turned out to be 4.4 liters tuned to 58Hz. The cabinet design calls for a bit of EQ at the bottom end: 2.8dB at 74Hz with a Q of 0.707



Above is the "final" design. There are some aesthetic points and a few printing issues that I'm not 100% on board with, but overall I'm pleased with the way they turned out. Waiting for paint...

The design shown is a two piece (top and base) hollow printed design. Meaning I designed each part as a solid piece and the printing service I used removed extra material in order to have a hollow closed shell as opposed to the prototype which I designed as open shells to be printed solid and closed with covers (see attached). It saved a bit of money and hassle giving the solid design to the printing service and letting them adjust as needed. I intend to fill the hollows with epoxy resin at some point but it feels like a little bit of overkill for now. They are lined with eggcrate foam, connectors put in place, wired, and then the top is press fit onto the base.

Listening impressions:

Wow! For the first few hundred hours on the drivers I had them sitting on my piano bench in the prototype boxes to break in. One day I put on Harry Connick Jr's eponymous album and went about my business in another room. I kept catching myself thinking someone was playing my piano, haha!

Now that I've had these properly set up and gotten some good listening sessions in, I have to say that these are really exceptional for near field listening. The imaging and sound stage are crystal clear. I can close my eyes and see each cymbal strike, make out the exact separation between instruments in an orchestra, on some tracks from The Beta Band 3EPs for example I realized that notes can have different shapes. Bass is clean, clear, and precise and is more than competent to all but the lowest EDM notes. I've become addicted to playing Billie Eilish's "Billie Bossa Nova" and James Blake's "Limit To Your Love" as the bass presence is just amazing.

The only issue I have with them is that they only really come alive at a louder listening volume than I'd like. These are intended to be desktop speakers for somewhat background listening. They do sound very good at those listening levels, but get better as they get some more power.

When I get a quiet moment I'll do some measurements. I especially want to see before and after of the result of filling the hollows.

Hi, currently I'm using pair of floor standers with single fullrange driver MA Alpair 10p.
Due to ongoing furniture replacement I decided to make new bookshelf enclosures for the A10p and then add a single subwoofer for 2.1 system.
The space for the sub is next to the TV stove - the red box on the picture and it will be next to a entrance to another room.


The available space will be enough for a box with external dimensions (from the point of view) WxHxD 260x650x480 mm
The gross internal volume is 60L (2.11ft3)



What do you guys think is suitable for this scenario?
The sub out of my 2+1 amp is rated as 38W@8ohms and 75W@4ohms.
I'm not going to use it for parties just for normal listening and movies.
I'll very much appreciate driver suggestions!
Thanks!

Bought brand new long time ago have been using to power my klipsch center channel speaker in my home theater
Can watch for long period of time everything fine but many times in the middle of changing over from commercial to a TV show or in the middle of a movie where the sound stops the amp clips and cuts out completely and then immediately restarts. What in gods name is this?

I am planning to build a sound system utilizing Art Welter's Keystone subwoofer design, outfitted with one of the suggested B&C 18inch drivers. Question I had was whether to go with 4ohm or 8ohm driver variants. 4Ohm seemed preferable because it would allow for greater amplifier headroom for a given amplifier, but then I came across a thread somewhere that suggested something to the effect of: "All else equal, a higher impedance driver/amplifier combination will sound tighter." I interpreted this as: Running from the same amplifier, 100db from an 8ohm driver would tend to sound tighter than 100db from an otherwise-identical 4ohm driver.

This led me down a rabbit hole, where I uncovered the following: this thread here partially answered my question with respect to physical construction of drivers. Summarizing posts #8 and #11: "lower impedance means not only thicker wire and less turns, but more moving mass in the voice coil - therefore, voice coil movement becomes "sluggish", compared to different , lighter coils, high frequency response suffers, same with "sharpness", transient attack". I also found another thread that I can't re-find that suggested the following, focusing on the amplifier & current: With total output power being equal, the higher voltage into the 8ohm driver equates to the amplifier having a stronger 'grip' on the driver. The hose analogy was invoked - for the same amount of water, the 8ohm load sees a higher pressure and therefore should be more responsive. Ok, got it - higher impedance has sound quality advantages.

The downside then would be current draw & amplifier strain/headroom, since an 8ohm system will draw more current than a 4ohm system run at the same power/volume and also utilize more of an amplifier's maximum output power. (Edited to correct backwards math.)

I'm willing to believe that the sound quality difference is meaningful, and I will prioritize SQ to the extent possible, but I don't have an unlimited amplifier budget for amps to provide ample headroom for the 8ohm load.

So - which way to go? I'm sure some of you pro audio techs have wrestled with this before - is the extra ~3db of headroom (assuming roughly double the power at 4 ohm is available from a given amp model vs 8 ohm) worth the tradeoff?

Greetings.
Need to add some “tube goodness” to the newest generation of class D modules. I could use around 3-5 db of gain. My question is, HOW do I choose the tube circuit topology when there are many options?

Let's start with unbalanced version and 3-5 db of gain.
Be able to drive 20K input impedance, not add a lot of noise and most importantly, give me some tube sound.

There are so many options that I have found, just Broskie alone has at least 6 different ones.
Deware zkit4: https://www.decware.com/newsite/zkit4.htm
Allen Kimmel mu linestage
Broskie aikido, https://glass-ware.stores.yahoo.net/9pinccda.html
lampizator anode follower with 6n6p

Of course, I would prefer simplicity and real good sound! What am I missing with lets say, Decware zkit4, one tube, double triode, as simple as it gets? Why go further and what would other designs bring to the table?

thanks!

Hi everyone,

I am going to be undertaking this procedure on my Kef Reference 3.2s and I could do with some reassurance!

I am just wondering what sort of glue I need to use to join the plastic dust cap/surround to the metal magnet back together once I have replaced the fluid?

Is superglue / Gorilla glue too strong?

For reference it's the two pieces shown here: https://audiokarma.org/forums/index...-pictures-and-a-question.709897/post-16063194

Thanks very much!

I am hosting a HIFI build for my company in my shop. This cabinet I have designed can only take the port up firing or down firing.

The feet of the cabinet will be 9-14.2mm depending on which one I choose.

Will the down firing port end up muffled by the table it sits on? Am I better off having the port come out of the top?

Used Power transformer originally wound for the Guinivere project about 20 years ago and still functioning as:
262-340-422-0 5V@3A 6.3V@3A

Leads are all cut but even the very short Primary long enough to splice. There is EAR SD-40 attached to the base and the bolts are brass..

USPS Ground Advantage estimates at $25 so that is the flat rate you will pay

Payment by US Postal money order only, sold as is

Just wondering have anyone use vfet to build guitar amps ? They have tube characteristics but not sure are all vfet the same

As the title says. I no longer need these and want to give them a new home.

Asking:
euro 100 for the Aerofara
euro 100 for the Volumio Primo HiFi Edition - sold
euro 100 for the miniDSP (note: the label on the back says Dirac but this is without a Dirac license!) - sold

All come with original power adapter.

The Aerofara comes with W10 installed and has the following connections on the rear and sides:
3 x USB-3, VGA, HDMI, SD card slot, Ethernet, Headphone.
Read the review here: https://www.cnx-software.com/2022/0...eleron-n5105-mini-pc-windows-11-ubuntu-20-04/

I am located in Belgium, will charge shipping at-cost.
Ask me for a binding shipping estimate to your location.

If you are desperate, make me an offer I can't resist ;-)

Jan

I'm looking for replacement filter capacitors for my amp and found a really good one, but by the spec sheet I can't tell the actual leakage current rating. Is 3 milli amps a maximum? Because if it was the actual one, then it's way too high. Here's the line from the data sheet:



Here's the full document: Datasheet

I would appreciate if someone could explain it to me and possibly tell the actual rating.

I was starting on a new speaker design using a Fostex woofer from their NX6A powered monitor. This 6.5in driver has a unique pinched cone and wrinkled surround, similar to the Purifi woofers. I got the bare drivers about 3 years ago for a blowout sale ($15 IIRC). Since these are not currently in production anymore, this speaker design would be fully open source and was being made for my personal DIY pet project (not commercial). I started to describe it here. Anyhow, after installing the driver in suitable cabinet that I had lying around, I proceeded to make some measurements to collect the FRD files needed to simulate the XO. The speaker looks like this. Tthe cabinet was an early prototype for another woofer and tweeter so none of the cutouts had rebates or cutouts that fit the NX6A woofer and a Dayton AMT2-4 tweeter that I had planned on using. So, I had to make some 3D printed adapters for the tweeter and for the woofer, I settled for surface (non-flush) mounting and will live with it.



So after putting the speaker with drivers installed and I took the initial sweep, I was shocked at the high level of distortion from 150Hz to 4khz, especially the 3rd and 5th harmonic distortion (note that distortion levels in legend refer to distortion at cursor location - which I am not sure if I kept constant - I would go by the vertical dB axis value though, you can see distortion peak at 64dB :


I spent the next hour trying to see if there was a setup issue, or something wrong with the electronics, wires, frame rattle, etc. All to no avail. But what I did notice was that the level of distortion was slowly going down with each sweep. I was playing with removing the vent tube, plugging the tube with stuffing, or leaving the tube in, thinking it might have something to do with it. Here are subsequent sweeps and you can see each one, the level of THD goes down a bit. the sweeps are chirped sound lasting about 5 seconds.

Number 2 (vent tube removed):


Number 3 (with vent tube back in):




Seeing the THD go down a bit, I tried running 45Hz at about 2.8vrms for 1 min to see if this loosened up the suspension: And it sure did!


So I tried leaving the 45Hz on for 60 minutes - distortion at 300Hz went down to about 34dB an apprximate 30 dB improvement!


I wanted to be sure it was not caused by the vent or lack of one or by plugging the vent, so I took a few more sweeps in different configs and now the distortion remained low:




Here are all the responses overlaid and you can see the effect of the vent/no vent/stuffed vent:


So I have left the speaker on playing music continuously for 3 days now, hoping that maybe I can eek out a bit more improvement. I have not checked again yet, but it seems the majority of break-in for this deiver occurred in the first hour playing some bass to really move the cone.

Here is the Wago plank crossover that I ended up with:


Measured response:



Overall distortion at 2.0Vrms and microphone 0.5m away:


Measured phase variation:


Pretty clean now. It sounds quite nice. But I think I have seen it with my own eyes and instrumentation - the real effect of driver suspension break-in on harmonic distortion. Has anyone else measured something similar? You can listen to the current speaker here.

Lightly used Nanodigi with power supply and remote control. $120 + shipping.

No international shipping.

Hello,
I know putting this out here, chances are slim.
This is ideally for pickup as a whole set. (~near Berlin)
If you are interested let me know if you want the whole or just parts of it
and we will work out a price that will be more than fair.

I already built test enclosures for this (2-way, ~40l, sealed so far) out of 18mm birch ply.
HF108 is used but working.
RS225-8 are brand new in box.

Optionally in addition to the speakers set (2xenclosure, 2xHF108, 2xRS225-8 & connectors)
I can offer an active XO and amps too if there is interest:
Minidsp 2x4, UMIK-1 USB microphone, two Ayima A04 and input selector unit with PGA2310.
I can also include a Vicor power supply 24V/10A.

Best regards from Fürstenwalde
Jens

In CDSP I am mixing 2 stereo channels to 8 (2x4) channels out to hdmi:vc4hdmi0. I expected that the channel mapping would auto-magically follow the CEA-861 CA=0x13 mapping. I.e. [FL, FR, LFE, FC, RL, RR, RLC, RRC].

In practice the CDSP outputs do not appear to follow this mapping at all. Based on listening to the AVR outputs they are currently mapped [RL, RR, RLC, RRC, FL, FR, LFE, FC]. I also suspect that this mapping actually changes in some sessions, but I am not yet sure what conditions cause a change. This is of particular concern for speaker x-over applications.

In contrast, the speaker-test application consistantly conforms to CEA-861 CA=0x13 (assuming the numbers it displays really are it's output channel indices.).

I did notice that the alsa Loopback device has auto-magically acquired several associated surroundXX plugs, but the hdmi devices have not. - this might be significant, or not.

Config: rpi4b, bookworm, os-lite, pyCamillaDSP 2.0.2 Backend 2.0.1, Onkyo TX-SR875 AVR

I would like to offer OLD NOS GU-48 tubes. They are mentioned in this my thread

https://www.diyaudio.com/forums/tubes-valves/365401-tube-amplifiers-pmc-eb1i-speakers.html

Before this 833A project, I have collected a lot of GU-48 tubes from russian traders. They there all in sealed original boxes. During the 833A project, I assembled a high voltage test unit, and heated up all the tubes with applying 1700-1900V voltages to plates. All tubes were stable in plate current after few minutes of heating, that is absolutely wonderful result for big tubes produced in 1972-1974 year. They are very good and reliable stuff, and I could select even "matched" pairs and quards, based on the one-parameter testing results.
I could sell up to 20pcs of these tubes, packed as pairs or as quards, with good packing quality. I want 125usd/pcs, plus shipment.

I recently got one of these back up and running (replaced the group of four small caps), but the output voltage is a little high at 122-123V (instead of 120V +/- 1V).

There are three trimpots inside, and I am guessing that one or all are required to adjust the output voltage.

Before I start experimenting, does anyone know what each of these trimpots adjust?

Amp

New in sleeve/tube. Ordered from Digikey in 2007.

Asking for EUR 80 plus shipping.

I am posting this review of Burson V6 in the solid state section because although its an Operational Amplifier but it is also a discrete OP AMP.

Couple of months back John Burson offered to send Burson Discrete Op Amps and I had to d a review in return, as my sci fi novel are in the final stages of completion I utilized my humorous acumen to review Burson V6 Vivid, so here goes:


In my recent escapade with the venerable miro1360 AD1865 DAC, enhanced by the magnificent Burson V6 Vivid discrete operational amplifier, I uncovered a treasure trove of auditory delights! Allow me to regale you with the saga!

Installation Extravaganza:

The Burson V6 Vivid's insertion was akin to a masterful swordplay manouver in a medieval epic - seamless and fitting like a bespoke suit. Kudos to Burson for making compatibility feel like a breeze on a sun-drenched meadow!

The Grand Sonic Melee:

Let's set the stage for our contenders: LME49720HA, LM4562, AD8620, OPA2134, and OPA2604 - each a valiant warrior in their own right. The Burson V6 Vivid, brimming with confidence, danced through this sonic battlefield, challenging each foe with unbridled enthusiasm.


Comparative Table:




The Burson V6 Vivid asserted its dominance, leaving the LM4562 in awe, coaxing the AD8620 into joyous sobs, and nudging the OPA2134 to strive for more.

Then came the grand showdown with the LME49720HA - a titan, a legend. These two clashed in a battle that resonated through the ages. The Burson emerged triumphant, but it was a contest that left no doubt about the LME49720HA's legendary status.

A Symphony of Sonic Splendor:

The Burson V6 Vivid, the maestro of this orchestra, conducted with finesse and flair. Highs soared like eagles, mids enveloped in a warm embrace, and bass reverberated like the heartbeat of a dragon. It was a crescendo of sonic ecstasy, painting vivid landscapes in the theater of my mind.

The Rendezvous with Spotify:

Connecting the DAC to my trusty iPad via USB and XMOS interface was a tryst made in audio heaven. Spotify, in its highest quality garb, serenaded my senses. It was as if I could hear the artists' very souls, etched into every note and chord.

A Time-Traveling Serenade:

Ah, but the true marvel came when the USB cable embraced my laptop, where audio was set at 24-bit and a resplendent 192 kHz. FLAC files from various artists graced my ears, transcending the boundaries of time and space.

Richard Marx's velvety croon swept me back to the golden days of heartfelt ballads. Celine Dion's powerful vocals carried me to a realm where emotions knew no bounds. Rahat Fateh Ali Khan's soul-stirring songs transported me to distant lands, echoing through centuries of musical tradition. And Pankaj Udhas, with his mellifluous ghazals, serenaded me through a journey of poetic elegance.

In each note, I felt the pulse of history, the heartbeat of artistry, and the essence of human expression. The Burson V6 Vivid had transformed my listening space into a time machine, and I was the fortunate traveler.

In the end, the Burson V6 Vivid left me spellbound. It's more than an amplifier; it's a conduit to a musical universe. While the LME49720HA put up a gallant fight, the V6 Vivid emerged as the resplendent victor, staking its claim as a force to be reckoned with.

Now on a serious note, listening to Music is more than just a few tests about spectrum, frequency response, distortion etc; to me it is a matter of personal preference, the audio setup, the room acoustics and a few other qualitative things, for me Bursons needed about a week’s burn-in time after that they really came alive. LME49720HA with heatsink after burn-in period is much too good. I have Burson v4 as well but I found V6 much better that the earlier versions.

I intend to put the Burson in my version of Bugle 3 clone, but that’s for later. Also I intend to pit it against @Vunce 's IV stage for DAC, that will happen when my TDA1541 DAC is ready, which is currently waiting for WIMA capacitors to arrive.

@John Burson , @miro1360

Here is how my test bed looks like:

Nelson appears to have re-spun the original Firstwatt beast, designed as current amplifier, good for fullrange speakers. It got good reviews originally, but not often seen (IMO) as a diy project. I think it's worth discussing here.

The addition of the F1J with SiC JFet's replacing the IRFP240 output devices may breath new life into the circuit. A single stage amp I think as refered as 'the truth machine'.

Here is what Papa says.. (Paraphrased)
The F1J is an update to the F1 where the two gain Mosfet transistors have been replaced by new state-of-the-art power Jfet devices. In addition, there have been changes to several resistor values and removal of the input zener protection diodes.
You may notice that the F1J also has approximately 1.5 dB more gain. This is because the Jfets have a higher transconductance figure that the original Mosfets.

There is another factor as well, which is that the F1J has a lower input impedance than the F1- approximately 30 Kohm balanced and 15 Kohm single-ended. The modifications that help achieve this bandwidth take advantage of lower impedances, so the F1J is recommended for use with preamps with ordinary to low output resistance – tube preamps without cathode followers will work but will not reap as much benefit at high frequencies.

This caveat aside, the F1J delivers a dramatic improvement in current-source amplification. I have often ventured the opinion that improvements in measured performance in simple Class A circuits (particularly with no feedback) usually have the best correlation between what you measure and what you hear, and the F1J bears this out. I think it sounds about twice as good, and I feel certain that you will experience the same remarkable improvements.

Maybe Nelson will share some details for those with the amp, maybe not 😛

Hello!
Hoping you all can help me understand this circuit and what/where are the critical components in the signal path. This is a 90's Aragon 47k/Acurus P10 phono stage one channel shown in the schematic. My goal is 'simple project' to practice my soldering skills, to try some resistor upgrades, and see what can be can be gained.
I understand R1-R6 are loading resistors, R10 is the input resistor, and Q1, Q2, Q3, and Q4 are transistors. I'm confused how the signal flow seems to split between C9 & C8 (which seem to implement the RiAA curve) and Q5 & Q6. I think R21 & R20 are the feedback resistors in this circuit? Q8 & Q7 seem to be output mosfets? Is R25/R26 in the signal path or just R27? I'd like to make a few part upgrades as the board and components are easy to work with and I have moderately competent soldering skills. Your help/feedback in identifying which resistors are in the signal path that would benefit from upgrading is greatly appreciated.

Happy Audio!

SOLD!

Up for sale set 20pcs of never installed/used/soldered/ DUAL-SHAFT gold-plated rotary switches Grayhill 81073:

- 10pcs two-decks up to 12 poles. By default manufacturer settings 8 pos high deck, 11 low deck, p/n 71CY231366

- 10pcs three-decks up to 12 poles. By default manufacturer settings 11 pos high deck, 3 low deck, p/n 71CY231367

All time kept in plastic bags in normal stable store temperature. Manufacturer specs attached.

Price - $280,-USD, FREE shipping across EU/UK.

Supplying from Ukraine with all distance tracking. PayPal payment way is possible with some specific.


Also possible for sale, can be put into common box to optimize shipping:

Grayhill 2, 3, 4 decks, single shaft rotary switches, up to 2x6, 1x12 poles

Canare Quad L-4E6S pro audio cable, 6mm 9 colors 97m

Mogami W2944 pro audio cable, 2.5mm 8 colors 236m

Some other items, caps, meters, call.

Hi Guys,


I have purchased a UPC1237 speaker protection board for an amp I'm building.



Assembled Speaker Protection Board 30A for Audio Amplifier Amp Omron Relay Delay 699938379519 | eBay


I plan to use a separate 12v power transformer to power the board.


My question regards how much current is required to drive the board.



I've had a good look at the datasheet but I can't identify anything that looks like current requirements.
http://www.unisonic.com.tw/datasheet/UPC1237.pdf

I have some AD1862N chips on the way from Rochester. They should reach me in a few days.
They can be reserved at US$160 a quad (registered shipping is included)
Digikey will not charge shipping but Rochester is charging US$28.
Then I have to pay import tax upon arrival.
Coupled with Paypal kind of exchange rate, packing materials for shipping, my time to run the logistics and transport, I am left with some coffee to chill for sending these to members.
I am sure you can do the Maths.
Hence it makes sense for me to sell in quads, otherwise it does not make economical sense to me.
However if you wish to buy just a pair and don't mind paying US$88 ( registered shipping included), I am willing to oblige.
Summarise:
4 pieces ( shipping costs included) = US$160
2 pieces (shipping costs included) = US$88

I can only accept PayPal Family & Friends please. Paying fees to Paypal + the kind of exchange rate does not make this price possible for me to help members to get the chips from Rochester. They now requires a registered company to make the purchase and they do scan companies to ensure that the chips are released to one that requires the use.

Reservation is by means of payment to my Paypal please, not just by words of commitment. So PM me when you are ready to do the transaction and I will give you the cue to pay.

Hi Thanks for reading A few years ago i purchased an asus stx II soundcard as part of a new htpc build. When the htpc was completed the audio was full of noises, buzzing, clicking, very disappointing.
Now i have a soundblaster ae-9 soundcard. Which motherboard do you think will work well with this soundcard to get me away from all the problems i suffered from my last build, which cpu and ram should I buy, which power supply. Which components will allow this card to work at its best? I want to take the audio out from the card's analogue outputs into separate stereo power amps for multichannel sound. I've looked at external dacs but they cost £thousands for the quality ones

Hello everyone, I was wondering if there is any way to fold a tapped horn that I have designed in Hornresp around the "BEYMA 15MC700Nd" driver without spending my whole life trying to do it 🙂. I'm familiar with Brian Steele's Excel sheets, but when I try to import the data from Hornresp using the "IMPORT SIM" button in the folding type "SS" excel, and then click the "OPTIMIZE" button, the sheet gives me an incorrect model, attached images below.
By the way, I know the mouth is 8920cm2, but even when I try it with another model like the "v2," image attached below, it still gives me a model with a weird shape or modifies "s1," "s3," and "s4," causing it to no longer have the same frequency response. I was wondering if I'm doing something wrong or if there is another way to fold my Tapped Horn. By the way, the final dimensions of the folded box don't matter to me; it can be any size. Any response will be greatly appreciated, thank you!!

So, here's the scenario:
I found a stash of transformers scavanvged from audio equipment but they have no useful markings or identifiers.
Is there any way to determine what if any good these transformers would be as output transformers? (besides building a tube amp and listening to the result)

I have access to pretty much any electrical test equipment you can imagine from handheld multimeters to spectrum analysers and VNAs but I just don't know and can't find how I'd go about testing this. Every method I have seen on the web requires you know at least one piece of the puzzle.

Thanks in advance, would be fun to not just design OTL 🙂

I believe I invented a new kind of speaker enclosure.

This is an "Open Baffle Reflex Hybrid" which has the upper half of the woofer exposed on the rear of the cabinet (dipole), with the lower half of the woofer reflex loaded.




A special divider (see center photo of the oddly shaped piece of wood) wedges across the middle of the woofer, creating separation between the open baffle top and the bass reflex bottom. This structure comes to within 1cm of the cone (left picture). Right photo shows the speaker before I installed the divider. The opening just behind the cone doubles as the bass port. There is no other port.


The closer I was able to get the divider to the woofer cone, the lower I could tune the port. A larger gap would tune the system to a higher frequency. A smaller gap would tune lower, but invite the cone slapping against the divider.

Below is the frequency & phase response in-room of the finished system:



This divider is air-sealed against the magnet and spokes of the frame with modeling clay. The tuning frequency is 57Hz which was the lowest I could attain, given the size of the enclosure (~1ft^3 / 28 liters) while not making the space between the divider and the woofer cone prohibitively narrow.

The impedance curve shows the reflex tuning:



About 1/3 of the back of the woofer is exposed and 2/3 funnels down into the enclosure. The polar pattern is really more like a cardioid. (However, I'm sorry I only have 180 degree polar plots, not 360.)


The polar spectrum shows a very even constant directivity of about 90 degrees from 100Hz to 20KHz. The tweeter is the classic Audax TW034X0 ("D34") mated to a 6.5" Troels Graveson waveguide, which makes a superb combination.

This is frequency response about 2 feet in front of the speaker. This position doesn't pick up the rear port radiation which is why you see the response droop below 150Hz. The farfield is better as you can see in a different curve above. This shows 1/3 octave plots at 0, 15, 30, 45, 60, 75, and 90 degrees. As you can see it achieves constant directivity from the bass midrange to the treble.



Below 100Hz the speaker becomes roughly omnidirectional with the majority of the output coming from the port. The port has a pretty decent bass peak at about 65Hz with useful output down to just below 50Hz. One drawback is that at high levels there's a fair amount of port chuffing. It's unavoidable given the narrowness of the port necessary to tune the box down to 55Hz.

A problem with this design for high excursions is that as the woofer moves, it is also changing the tuning frequency at the same rate as the signal is varying; so that creates some cringy distortion at high levels. Also it's likely I am getting cone rocking at high levels because of the asymmetry of the air loading. But it's less distortion than the same woofer in a dipole at the same volume level :^>

The Dayton RS270P is an excellent driver. It’s used in some pretty expensive commercial designs. It’s good looking, has very smooth response, has a hard pressed paper cone which makes a very incisive crisp character.



I used DSP to straighten out the anomalies, of which there are several. ABOVE, see graphic of the DSP bass EQ correction curve, labeled according to which problem is being fixed. It would be pretty hard but not necessarily impossible to execute these with a passive crossover. It would take a lot of trial and error. Not pictured is 3rd order 1500Hz xover between woofer and tweeter. The MiniDSP introduces a sharp high-pass filter below 50Hz which protects the woofer from too much excursion. Very important.

I used FIR DSP all pass filters to correct the phase response so the system is linear phase from 100Hz to 20KHz with outstanding impulse and step response.




I could perhaps have patented this unusual enclosure design. But I don’t care to be in the speaker business, and as a business consultant I think most patents are overrated anyway. So I’m giving the design away here.

They are biamped. You can download MiniDSP file here.

This is the cabinet sketch I gave to my Chicago-based carpenter, Seth Cothron, @studio38designs.



They sound fantastic. The stereo image is wide and full; they have more bass than a 10” in a straight dipole would produce, and they produce the warm ambient sound you expect from an Open Baffle design. You can't push them terribly hard in the bass (more of a jazz speaker than a rock speaker) but they certainly play a lot louder than if they were normal dipoles; they can play roughly as loud as if this same 10” woofer was in a sealed box.

The imaging is superb everywhere in the room, even standing right next to one speaker; and they are very transparent with great clarity.

On the back panel is also a Peerless 1" dome tweeter BC25SC06-04 for back fill - I find dipoles sound much better with full spectrum on both sides.

Below is the tweeter schematic. The tweeters are wired in series and the LC circuit reduces the sensitivity of the rear tweeter while making the front and rear tweeter curves match better. Woofers are wired straight to the LF amp.



I built these two years ago, and a friend suggested that maybe it would be easier to just build a dipole with two separate woofers, instead of creating all of the baffling necessary to divide the output of one. So I did, and the result was the Flanagangsters which I posted about 2 months ago.

I really enjoyed trying something unconventional and I encourage y’all to generate variations of this new enclosure type.

Perry Marshall

Hello everyone!

I am on my 2nd Tube amplifier project (but I have quite good SS background), and I have some 6N13S tubes which I am looking forward to use as my power output tubes.
I came across this schematic which was published in Elektor 2007 but I would rather ask for some opinions about it before I start designing the PCB.
To be honest, what seems weird to me is the connection of the grid resistors of the second stage, which in my opinion should be connected to GND.
As I said, I am learning a lot so I might be wrong. Hopefully someone will explain what's happening there. I am also keen to upgrade the existing schematic eg. CCS for V1,V2 cathodes, etc.


Kind regards.

Thought this new amp from Peachtree Audio deserved it's own thread. Enjoy!!

This Peachtree could be something, it uses the far faster newest "GaN Technology" (Gallium Nitride) output devices, not Mosfets like Class-D uses.
1: has no dac in it per se, just has a (programable?) DSP processor chip to convert PCM to PWM at the end just before the GaN power output stage.
2: is zero feedback
3: no preamp is used
4: and has no buffers
5: has impressive low .004% THD, very good for an amp without any feedback!!!,
6: It just takes in the digital output from your digital source/s (it has no analog inputs).

Addicted to Audio has the older Peachtree line but not this new GaN-1 "digital-amp" yet.
Busisoft the Au importer said they'll be in soon, but yet to have an RRP put on them.

This is Peachtree Audio, and the new GaN Technology with this digital-amp, that is direct digital input from your source/s.
https://www.peachtreeaudio.com/products/gan1

Here's JD ex-Aussie, (gone back to his Pommy roots,) John Darko's very descriptive high praise review on it.
Login to view embedded media
Cheers George

So... here is the thing. I bought this Reisong A10 a few weeks ago and out of the box it was sounding terrible. At least matched with my Castle Conway speakers. So I started digging, reading and watching videos on how to mod it. I got to make some mods and tube rolling that enhanced the sound but... I'm still missing things. Rock and other "non-vocal/jazz/classical" tracks sound muddy. I need to add that I've no idea what I'm doing, I just follow the modding videos I find 😅. It was on one of them that I heard about bypassing the orange coupling cap (0.22uf) that came from factory with a copper foil cap (0.1uf).

Now, here is the "big question". I'm ready to spend some bucks on this bypass cap, but these questions came to me:

1. Sonically speaking, is it better to just replace the cap or bypassing (parallel) it with a lower capacitance would get more improvement?
2. If the case is the second, the capacitance of the bypassing cap affects the sound? Meaning, would it have more impact (improvement) if the bypass cap had 0.1uf than a 0.01uf? I ask this because I'm looking at some Duelunds that are quite expensive depending on capacitance.

That's it. All said (or asked). Please be kind to me, it's my first post.

In this exciting episode the possibility of Intermodulation Distortion Reduction in a Class AB2 amplifier by the Allen Wright method is tested.
The amp output is PP 6V6s driven by a 6BQ7 as cathode followers direct into the 6V6 grids, Refer to the schematic,

The driving signal in 80 Hz mixed with 4.7 KHz at 12 db lower level, The measurements follow the SMPTE method.
In test A the 6V6 cathodes are taken straight to the commons rail with the exception of small resisters to allow current measurements.
At 5 watts the IMD measured 1.87 %.
In test B a 47R resister was inserted into the 6V6 cathodes lead to common. The IMD increased to 4,67 %.
In test C the common resister to the common rail was 23R, And the IMD was 3,48 &.

The Allen Wright method did not improve the IMD in this amplifier. 🙂

This is a blank PCB for 9 pin Aikido line stage PCB that has a built in power supply. Can be configured as a headphone amp too.
Broskie's PCBs are first rate.

These are no longer available.

Comes with manual. Priced 25% below cost.

$49 + nominal shipping.

Hi everyone,
I was looking for some woofers that I could use for a car audio system. At the beginning I wanted to use four Peerless SDS P-830657 6.5 inch woofers, but then I found the Tang Band W4-1052SD 4 inch woofers. The plan is to cross them over with tweeters anyways. Do you recommend the bigger sds ones or the tang band speakers, considering they're higher in price (and probably quality) as well?
I forgot to mention that I will have a subwoofer for lower frequencies

I think GM can help me here,
Does anyone know the difference between sectoral horn and diffraction horn ? is birdial horn the same as diffiraction horn

​

Also I was looking at yamamoto F350ii , https://www.hifido.co.jp/sold/18-16007-16304-00.html and trying to understand is the cut off freqency 600 hz or 350hz.

thank you

Hi All!

After some good advice and areas to look further into after my first post on the forum, I think I've selected a pair of drivers for my 2.0 build and hope that others might be able to take a look and let me know if I've overlooked anything or might be leaving performance or money on the table.

I plan to use Peerless D27TG35-06 Tweeter and Peerless 835025 6-1/2" Aluminum Cone HDS Woofer with a passive crossover that I will build around 2.5kHz.

I've calculated a vented box volume of 0.553 ft^3 with a 2" D, 4" L flanged down-firing port. I selected down-firing based on the location the speakers will need to be placed in; roughly 3' from listening position with 1.5' of space from the wall for one and window for the other on the side, and 2' from the back for another wall and window. Overall room size is about 10'x8'x11' which I will be treating after getting the setup together.

I'm currently in the process of building the Leach Amp to power this setup.

Looking forward to any feedback!

Hi,
I want to improve some components of my crossover and I would need information. I attach the diagram to better understand. The crossover is in two parts.
The first part of each lane is at the bottom of the enclosure (to the left of the dotted vertical line)
The second part (to the right of the dotted vertical line) is located at the top of the enclosure near each driver and is connected by a cable with the bottom part.
Is there an any advantage to separating and placing only this part of the crossover close to the driver?
Also, in the diagram at the bottom right, is a circuit connected in parallel with the input terminals. What is the purpose of this circuit?
I want to separate the mid-tweeter and the woofer to be able to go in bi-amplification, do I need to make a copy of this circuit
to have one for the mid-tweeter part and the original for the woofer? or is this circuit is usefull for the woofer or mid-tweeter only?

Thanks

I am passing this along to the next enthusiast interested in listening to this amp from creator extraordinaire Nelson Pass - the original vfet lottery. The amp is perfect no blemishes and has maybe 50h on it and comes with the meanwell SMPS. I am very experienced builder so no bad solders burned components etc. The kit was 500usd and l would like to get it back. Buyer pays shipping. Will be packed to withstand UPS handlers.

Hi all

I’m quite new to electronics so be gentle.

I know enough to reasonably diagnose a guitar amp problem but as this is my first time with actual soldering iron in hand trying to fix things I would like to run my theories past experts first.

The amp
It’s a G10 Marshal (no reverb, twin gain pots, high middle low equaliser pots and master volume)

The problem
The gain controls produce really bad hiss even at low settings.

My thoughts on fixes
Visual inspection of the board I find no visible problems (cap leaking, dry joints or burns on components)

So do I suspect coupling caps are leaking DC - it’s my go to pat idea for hiss

Tools available
I have basic multimeter + DSO TC3 meter
To attack the problem.
I’m very competent at soldering

I’ve got a schematic of the circuit (very grainy print) but useable.

So how to trace this problem so gratefully for any help.

TIA
BTW - it’s 20+ years old

First of all, thank you for your interest.
Due to lack of time and too many projects, I offer an Ear 834 clone diy kit from Douk Audio with Mouser components, transformer choke, Mundorf caps. I have a list where the existing parts are listed.
the entire package cost me €300.
I'm offering it for €250.
Ask for shipping costs.
If you are interested please let me know.
kind regards abc4230

I dont see all-pass in their 2 way plugin, can miniDSP do all-pass filter, if yes, then using which plugin software?

Thanks and Regards,
WA

Well, after making a rash purchase from eBay (should have bought a guaranteed good one from Bensen when I had the chance) and hoping that it’s a non-fake working chip I now realise I have no clue how to use it. I will need to put it on a board and make connections to it.

My question - I don’t see many people adding any heat-sinking. Do these chips get hot? Would cooling increase the life expectancy? Is there any point to trying to cool the package or does the heat get out via all those pins? If the heat has to be removed from the pins does that imply some design constraints? Is there even a case to be made for Peltier cooling for better performance?

Hello, can someone help me identify why my power supply drive looks like this?

It looks the same all the way back to the MC1 but just with a lower voltage pre-drive buffer.

Rail voltage is too high, 204vdc. Amp comes on with blue light only but no drive on the outputs.

The drive buffer ucc27524 is verified good.

Hi ... I'd like to run two of same dacs for my stereo, but thought better ask first.
I have a Cambridge Dac Magic 200m. Upgrading would be too expensive for me, but could get another 200m. I'm using mono blocks so thought one dac per channel might be advantageous.
Zene

I purchased a NAD 3130 on Facebook Marketplace with one channel dead, the other is working. On removing the two To3 Transistors (2N3055 & MJ2955) I noticed that the track on the PCB from the transistor fixing bolt hole was bridged with solder to the adjacent track, as I have marked in red in the attached photo 1 & 2. In photo 1 you can see the solder bridge between the fixing bolt and the adjacent track and in 2 you can see I have removed the bridge. This amp has been repaired before, is this a modification I'm not aware of or just a poor previous repair?

I have the service manual and from what I can see the short in the photos should not be there on either transistor?

Any help or advice would be welcomed..

Edit May 28, 2020: Revised Schematic and BOM for 2SK209GR JFET and ZXMN10A08GTA MOSFETs here: xrk971 Pocket Class A Headamp GB

Edit (July 24, 2017): schematic with DC setpoints for actual standard build amp using suggested values in recent BOM. Note that adjusting R4 (as high as 51R for higher bias) gives room for tuning desired bias current vs battery life. Voltages here are useful as reference for debugging a circuit that is not working:


Edit (June 2, 2017): A review of this amp on Headfonics.com



This project started over in this thread:

BF862 based SE Class A Headamp without the HEAT

but I thought it would be good for it to have a dedicated GB thread here. It's a superb sounding single ended (SE) Class A topology that has a predominantly a second harmonic distortion profile with just a tad bit third harmonic and not much else. The noise floor is about -125dB and dynamic range is about 96dB with THD measured to be about 0.029% at 1kHz and driving a 270ohm load at 700mV RMS. Note that most of that HD is H2 so the sound is very much like a nicest SE tube amps. Frequency response with a 47uF output coupling cap was measured at -1.5dB at 20Hz and 45kHz (probably limit of measurement as ADC sampling was 96kHz). The sims show that it can go beyond several MHz on the high end. Best part is that it fits in an Altoids tin and looks like a CMOY headamp - but it's no op amp. It relies on just two FETs. The ever popular BF862 JFET for the input and a ZVN4306 MOSFET for the output stage. The bias runs between 50mA and 60mA which allows it to last about 4 to 5 hours on a pair of 600mAhr Li-ion rechargeable 9v batteries. The amp dissipates about 2w so never gets hot but makes a nice hand warmer for your pocket in the winter.

This is the basic circuit - very simple and it's what gives it a natural and very musical sound that is engaging, lively, never sterile.



Here is the predicted HD profile:


Here is what the hand made prototype looks like:


You can listen to this amp as recorded with UCA202 connected to a 270ohm load resistor. Change the file name extension from .asc to .mp3 to listen.

http://www.diyaudio.com/forums/atta...wo-transistors-clapping-pocket-class-clip.asc


This is the layout for the actual board being sold for this GB:


This is the associated schematic that goes with this layout:


Many thanks to BabyDontHertzMe (BDHM) for making the layout and to Agdr for providing the initial Altoids footprint Eagle file.

Here is the measured HD using Focusrite Solo 2nd gen at 96kHz and 24bit:



The HD measured using a UCA202 at 16bits and 48kHz looks like this:



Edit Feb. 18, 2017 - Here is the latest measured frequency response and THD from the GB PCB:


Edit Feb. 18, 2017 - Here is the latest measured FFT from the GB PCB measured for 1kHz excitation at 700mV into a 270ohm load:


This headamp can drive headphones with impedances as low as 30ohms no problem. The GB has already started in the other thread and is currently at 6 people and 11 boards. We have enough critical mass but I want to keep it open a bit longer to make sure everyone who wants one gets to place an order.

Please send me PM for pricing of bare PCB's or matched FETs.

Pre-made amps and pre-soldered SMT-only boards and full kits available here:

XRKAudio designs for superb natural sound. by XRKAudio on Etsy

Please use the quote feature to add your name and desired number of boards to grow the list:

Pocket Class A GB Order List:

(As of 02:00 EST, Jan 29, 2017)
xrk971 - 2 boards
pcgab - 2 boards
zman01 - 2 boards
stellarelephant - 2 boards
samoloko - 1 pcb
lui04 - 2 boards
Morde - 2 board
cyteen - 2 boards
funch - 2 boards
syyma - 2 boards
av-trouvaille - 2 boards
Mituisho - 2 boards
bogde - 2 boards
faltinsen - 2 boards
vanofmonks - 1 board
M_Balou - 2 boards
dwpeterson - 1 board
agdr - 1 board

(add your name and number of boards here. Please use quote feature to grow list.)
Report Post

Click to expand...

Latest BOM is post 15:

xrk971 Pocket Class A Headamp GB - Page 2 - diyAudio

BOM errata for C9 and C11:

http://www.diyaudio.com/forums/group-buys/302859-xrk971-pocket-class-headamp-gb-4.html#post4971339

Edit - Jan 9, 2017: The GB PCB works! Sounds fantastic.





Final as-built schematic:



Final as-built BOM:

All resistors 0805 package, metal thick film, 1% on specified parts, else 5%. Yageo 1% 0805 SMT from Digikey are $0.77 for 100
R1 100k (5%)
R2 47k (1%)
R3 1k (1%)
R4 33R (1%) ** try experimenting with 39R and 47R to give higher bias current but more H3 and less H2 but overall lower THD **
R5 270R (1%)
R6 47R (5%)
R7_1 470R (1%)
R7_2 470R (1%)
R7_3 470R (1%)
R7_4 470R (1%)
RL 270R (5%) User select (optional, use for higher current draw on amp)
RLED 15k (5%) Current limit for LED, 15k or value according to supply voltage

C1 Input cap 5mm pitch up to 5.5mm wide (Wima 2.2uF MKS2B042201F00JSSD)
C2_1 Output cap 3.5mm pitch, 8 dia (390uF 20v Panasonic OSCON 20SEPF390M) or Nichicon AK 470uF if you can fit it Edit: I highly recommend a 1000uF 16v OSCON here for low impedance phones.
C2_2 Output cap 5mm pitch, up to 9mm wide (Wima 1uF MKS2C041001F00KSSD) Edit: I highly recommend a second 1000uF 16v OSCON here, if you have 30ohm or lower phones, and place Wima on SMT side.
C3 Rail cap 100uF 3.5mm pitch, diameter whatever you can fit in the tin (100uF 20v Panasonic OSCON 20SEP100MX) - or Nichicon 2200uF 16v lay on its side
C4 Rail cap 100nF 1206 package (50v X7R)
C5 Additional 100nF rail cap 1206 package (50v X7R)

Q1 BF862 (771-BF862-T/R)
M1 ZVN4306GTA * a great alternative is ZXMN10A08GTA now that 4306 seems to be out of stock or EOL? **

Switchcraft 3.5mm stereo jacks x2 (35RAPC4BV4)
Alps 10kOhm stereo pot with power switch (RK0971221Z05)
3mm round LED (red or green)
4-pin 2.54mm pitch power connector (see post #44)

Click to expand...

Edit (Dec 22, 2017) - here is the latest BOM that I use for low impedance cans with a smooth sound signature:

http://www.diyaudio.com/forums/group-buys/302859-xrk971-pocket-class-headamp-gb-140.html#post5284641


Here is a Digikey shopping cart for all SMT parts. Good to have assortment of R4 values ranging from 33R, 47R, 51R, 56R, 68R to tune bias current on M1. Start with 47R and increase R4 for higher bias - aim for 50mA to 55mA across R7.

Here is a ONE-STOP shopping cart for Digikey put together by Sodacose. It doesn't have the nice red Wima's but should be fine if you are not a capacitor snob 🙂

http://www.digikey.com/short/3wzbtt



Here is the template for drilling the holes in the mint tin, courtesy of Agdr (same pattern as his Super CMOY 1688 as the pot, LED, and 3.5mm jack locations are the same).

https://www.diyaudio.com/community/threads/xrk971-pocket-class-a-headamp-gb.302859/post-4985588

Desktop version with IRF10's and 115mA bias here:
http://www.diyaudio.com/forums/group-buys/302859-xrk971-pocket-class-headamp-gb-38.html#post5014544



Edit (July 28, 2017): DSP Convolution Files for OB-1 and DT880-250 headphone!
Here is a neat thing to try if you want to hear what your headphone would sound like if it followed the ideal Harman target response. Byrtt posted some directions on how to do this in DSP and kindly provided convolution files for DSP processing of the OB-1 and DT-880 headphones (I happen to own both 😀). Sounds very very nice - definitely worth a try.

http://www.diyaudio.com/forums/group-buys/302859-xrk971-pocket-class-headamp-gb-100.html#post5134580

Edit Aug 28, 2017: a very nice USB LiPo charger and load balanced with cap multiplier mod by RaptorLightning.

http://www.diyaudio.com/forums/group-buys/302859-xrk971-pocket-class-headamp-gb-118.html#post5168688



Edit May 9, 2018: Schematic and BOM for the Desktop Class A Headphone Amp:
http://www.diyaudio.com/forums/group-buys/302859-xrk971-pocket-class-headamp-gb-173.html#post5428007

PCB layout courtesy BDHM and JPS64:




Stuffing guide:




Update Jan 8 2019: New ZXMN10A08GTA to replace ZVN4306GTA provides higher transconductance for lower output impedance and higher damping factor. xrk971 Pocket Class A Headamp GB

Update Mar 6, 2020: New Resistors for 2SK209BL and ZXMN10A08

Hi everybody,

I am a musician and I want to start building some pedal effects, pre-amplifier, filters and so on. Just for hobby 🙂
My target is to learn starting from descrete components (I think it is the most basic level, isn't it?), so my first project is to build a simple pre-amp using a transistor in a CE set-up.

I was experiecing some buzz/hum problems with my CE amp. Since I want to learn, I attach a detail report and two recordered audio instead of write here.
At the end of the report there are my questions 🙂

I hope this is the right way to explain to the comunity my troubles and I hope this will be helpful to somebody.

Thank you

Andrea

Hi all,

I have several power amplifiers that are used to run a vibratory shaker table that I own and some of the BUZ210 N-Ch MOSFETs are testing bad. There are nine of the amplifier modules in the controller cabinet with 20 BUZ210s on each module for a total of 180 FETs. I'm looking for a replacement MOSFET to the BUZ210 and have nearly given up on finding one in a TO-3 package. I'm considering spinning a custom PCB to adapt a surface mount MOSFET to the TO-3 mounting holes and heat sink, but I do not know how close I need to match parameters like input capacitance, transconductance, charge, etc.

The specs for the BUZ210 are attached. I'm considering something like the IRFAC50 (TO-3) package, or something like the AOD380A60C. The BUZ210 has an input capacitance of 3800 pF @ 25 Vds. The parts I'm finding that meet Vgs and Id specifications have much lower input capacitance (e.g. 900 pF @ 100 Vds).

How close do I need to match these other parameters for a power amplifier like this? The amplifier energizes a very large field coil to create a field that moves the shaker table up and down. I also attached a picture of one of the nine amplifier modules. Some of the BUZ210s are removed for testing.

Thanks!

The existing power supply in my audio amplifier lets quite a bit of ripple through producing audible hum. I am planning to add an LC filter to the existing power supply to help filter more of the ripple. I have included a schematic of the power supply with notes showing what I plan to do. After running a simulation in PSUD2 this should greatly reduce the ripple on the B+. The issue is that there is not room left in the amp chassis for this new LC filter. I am planning to mount the new LC filter in its’ own chassis and connect it to the existing power supply using this cable, making it as short as possible. The cable will be for points A, B, and GND shown in the schematic.

Does anyone see an issue with this?

Thank You for your help

Kemet and Vishay 900V 5%, 18Arms 2+2pin connection
They are NOS, I precision measured 100+ of them and grouped matched pairs and triples for use where matching is of advantage
(circlotron PS, Xover, a.s.o.)

The title almost says it all - I'm looking for a Cambridge Audio 640A v2.0 Service Manual - I've got the 640A SM dated 2003 revised 2008 (SERVICE MANUAL – AP14676/1) but I've yet to be able to find a v2.0 - is there one out there. There seem o be others that have looked for it but none seem to have found it yet Please 🙂

Hi i recently bought a Fnirsi 1014D oscilloscope which has an inbuilt function generator. But the amplitude of the signal is fixed at Peak to peak 2.5V. I tried connecting a volume pot on the out to reduce the amplitude but the signals came out distorted, Is there any way to make it variable by adding an external circuit?

https://www.elektor.com/blogs/review/fnirsi-1014d-digital-storage-oscilloscope-review

We released a new audio op amp this week specifically targeting ultra high fidelity headphone amplifier applications: http://www.ti.com/product/OPA1622

Some of the highlights:

• 80mArms linear output current (+145/-130 mA short circuit)
• Extremely low distortion into low impedance headphones: FFT on the front page of datasheet shows -133.6dB 2nd Harmonic at 50mW into 32 ohms
• Ground-referenced enable pin compatible with 1.8V logic and click/pop suppression. 5uA of supply current in shutdown mode.
• 2.8nV/rtHz input voltage noise
• 0.8pA/rtHz input current noise
• 2.6mA supply current when enabled
• 136dB open loop gain with 600 ohm loads
• Stability with >1nF cap loads in a G = -1 configuration, no isolation resistor
• Very good PSRR: 97/123 dB at 20kHz.

I know the package really isn't hobbyist friendly (3mm x 3mm SON-10) but I thought it would still be an interesting product to many on here.

Anyone no the code to reset that player?

Hello,
Due to the fact that you can't buy new, at least half decent tape deck today and that my AKAI CS-F21 is having more and more problems do to it's age, I decided to build a tape deck mainly from old parts that I have laying around.

Tape deck from 2000 BMW 5 series radio made by Becker... soft buttons, plays A & B sides one way, motorised tape loading, photoresistor sensor on both reels...
I didn't do any measurements, but the sound is really nice, even with old beat-up tapes...
I solved the logic with Arduino and it does the job good... I still need to add A-B side logic and photoresistors logic...


For the preamp I will copy design from another BMW unit... 2000 BMW 7series navigation unit made by Phillips (basicly tape player, keypad and display in a package, amplifier and the main logic is seperate unit (in the trunk).

I will copy the design and build my own, because it just sounds so good, has Dolby NR B-C, norm and metal tape option, side A-B play, mute detection...

For now I"m testing with the original board, bricked to turn on without main unit (the one from the trunk).

Audio signal goes to the BA3430FS tape preamp, then to the HA12161FP Dolby IC and then to the TDA7053AT.

According to the datasheet TDA7053AT is an Dc volume controlled amplifier and I am wondering if I need it because I get good signal from DOLBY IC.

Can I take the signal from DOLBY IC? The new DIY unit will not have it's own amplifier, just line output at the back -possible short circuit scenario...


I was thinking about why Phillips added TDA at the end of signal chain and my assumptions are:

-Short protection
-Dc volume control
-Impedance matching (I don't have the main unit, so I can't confirm)
-Because the main unit was so far away in the trunk:
-amplification
-solution to ground loop noise problems as TDAs output is floating 5v above the power gnd


What do you think? Would you keep the TDA?

Thank you for help

Hi. I was thinking about improving the DAC in the Arcam CD72 player. Currently there is PCM1716 dac. I would like to put WM8740SEDS dac chip instead. Pin by pin they seems to be the same. Could someone advise me if it is enough to "resolder" the chips or I need to do something else?

Model DCA75

Complete with original manual, like new, but without original box.


EUR 100 including registered postage in Europe, EUR 104 overseas.
PayPal family & friends, or SEPA transfer.

Hello and thanks for tuning in to this thread. This is my first speaker build and post on the forum, so please excuse my ignorance of some of the finer points of speaker design.

This prototype build is a tri-amp clone of the Danley Sh-50 with active DSP processing. My goal is to get 60hz to 16khz with a pretty flat response and operate around 130dBc @ 1m.

So far everything is working great at the desired volumes but I would like to improve the phase of the speaker and maybe get some feedback on ways I can improve this build before I commit to building the final pair in 3/4 Birch. Any comments are appreciated!

***
Attached is a picture of the SPL/ Phase response in REW, measured at the center of the horn opening with calibrated levels and RTA mic.

XO: CD (HP -48 Linkw @1350hz), MIds (-12db Butter Low Pass @ 1350hz and HP -12 DB Butter @ 350hz), Sub (HP -48 Linkw @ 60hz and LP -48 Linkw @350hz)

EQ: Peak EQ boost at each XO q=1 +8db

Build parts list:
3/4 MDF
Ashly Protea SP 4.8 DSP
PRV 290PYS
4x Pyle 5" Sealed Mids
2x Faital 12FH510
Amps:
EV CP1200 - CD
EV CP2200 - Mids
EV CP3000 - Sub



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Hello everyone!
I am currently designing a simple pass-through application for I2S audio on the STM32F072RB microcontroller. Basically it receives data on one of its I2S peripherals and forwards them to the other I2S unchanged. This is done using double buffering and a DMA is utilized on both RX and TX sides. Both I2S are in slave mode on the same clock domain. The source of the audio signal (I2S master) is the Up2Stream Mini bluetooth module from Arylic. The power end is the TAS3251 chip which takes the I2S data coming from the STM32 directly. Later I would like to enhance this application with some low/high pass filters, volume control and FFT.

But what is the problem: sometimes just after the powerup/reset the receiving I2S is somehow unable to lock on the incoming clock and that results in the entire transmission being corrupted (noise or silence coming out of the STM32 - see the video where I repeatedly reset the MCU and few occasions show the corrupted audio). I have quite isolated this problem and I am 90% sure it is caused by the receiving I2S. But what I don't know is the root cause and if it is the wrong locking on the clock, how to recover from this?
Both the receiving and transmitting DMA runs in circular mode, so there is actrually very little code to implement this whole thing - just an init and one ISR to swap the dual-buffer.
I am also attaching screenshot of the receiving I2S config.

By any chance, is there someone who has an experience with I2S audio on STM32 and can give some hints on resolving this?

Thanks and Happy New Year to everyone!

Hi all

I fixed my brother's mission cyrus two for him recently (pre amp power supply circuit track fault and a sulphided selector switch. He now thinks I'll be able to fix his daughter's cyrus one.

that's a bit sicker though.

when i plugged it in one of these white things glowed red and started smoking.

I assume this isn't good and unplugged.

So I'm guessing (wildly, cos I'm not knowledgeable) that a transistor has gone open and too much current ran through the white thing ?

<a href="https://ibb.co/mtvZVG"><img src="https://thumb.ibb.co/mtvZVG/20171209_174840.jpg" alt="20171209_174840" border="0"></a>

I thought I'd replace the white thing, and all 4 output transistors but they all have the same marking on them (C8837 CYRUS PT7) and i expected each channel to have a pnp and an npn ? Im also guessing they aren't made by mission and are obsolete.

could they be different but have the same code marked on them ?

can i test them with a multimeter or will that not work cos of failure ?

I could do with knowing what to order.

thanks for any help

I have four Max Pentavent 1250 drivers for sale. These were used in an open baffle speaker project, but not used enough to be run in. They are in perfect condition.

These cost me £60 each back in 2005 and I will accept £70 for a pair or £120 if somebody takes all for. Shipping extra of course.

Incredible bass drivers designed to give
exceptional performance in a wide range
of applications.
With the precision and speed to satisfy the most
discerning listener and a robust, superbly engineered design
to handle the massive output of powerful amplifiers, these
drivers can deliver superb sound quality across a wide
bandwidth. Long excursion coils and low resonance push the
bass frequency performance of these drivers well past what
has long been considered ‘the standard’ to a depth most
drivers only dream of, making them ideal for subs, whilst
excellent midrange extension and a smooth roll-off make
these drivers ideal for any high quality 2-way or 3-way
system.
• ‘Pentivent’ 5 vent design for noise free cooling
where it is needed right into the heart of the voice
coil.
• Multilayer Kapton KSV voice-coil former for
high power and performance (K2= 2 layer, K4 = 4
layer).
• Graduated rubber surround for long lasting
performance, low resonance and excellent
damping.
• I.M. cone impregnated with carbon for excellent
rigidity and very high strength to weight ratio
minimises cone break-up and lowers distortion.
• Anti-resonant black chrome chassis with oval
windows and high quality steel to reduce basket
resonance.

Hello,
Can someone recommend a free program to convert from .NRG to .FLAC.
I've already checked the first Google results, but either they don't work or they want money for such a conversion.
I don't have many images and it's not worth investing in such a program.

Hi,
once there were a number of either spring reverb drive and recovery amplifier circuitries at the ::::::::: Accu Bell Sound Inc ::::::::: site. But nowadays this site appears to be down. Is there any chance to find these circuits again?
Best regards!

I have a speaker with the below specs that I currently use as a subkick microphone (speaker wired in reverse)
I would like to add a passive low pass filter and understand that I would probably need an inductor coil, my question though being an absolute electronic newbie, what kind of coil would I need and would this cause problems to the electronics of my sound card receiving this signal?

much appreciated legends.

Specification Sheet 165mm Polypropylene Bass Driver Description 165mm (6.5") speaker • Ideal for bookshelf hi-fi speakers • Polypropylene cone • Pressed steel basket Driver Parameters Electrical / Mechanical Voice coil resistance (Revc): ................................6.6 Ω
Impedance at Fo (Zo):........................................40.8 Ω
Resonant frequency (Fo): .................................48.4 Hz
Effective piston area (Sd): ..............................0.013 m2
Force factor (BL): .............................................6.23
TM Sensitivity (SPL): .............................87.5 dB @ 1W/1m
Acoustic volume (Vas):........................................20.7 L
Mechanical Q (Qms): .............................................3.36
Electrical Q (Qes):................................................0.648
Total Q (Qts):........................................................0.543
Compliance (Cms):...................................861.36 µm/N
Total moving mass (Mms): ...................................12.5g
Diaphragm mass (Mmd):......................................11.7g
Voice coil height (Hvc):......................................7.8 mm
Air gap height (Hag): ............................................4 mm
Maximum linear excursion (Xmax):...................1.9 mm
Motor Impedance Voice coil inductance @ 1kHz (Levc1): ...........1.03 mH
Voice coil inductance @ 20kHz (Levc2): .......0.474 mH
Resistance constant (Krm): ...........................0.776 mΩ
Reactance constant (Kxm): .............................10.1 mH
Resistance at 1kHz (Res1):................................2.26 Ω
Resistance at 20kHz (Res2):............................34.86 Ω
Resistance Exponent (Erm): ..............................0.9123
Reactance Exponent (Exm): ..............................0.7394

I've been playing on box simulation softwares: WinISD and BassBox 6 Pro.

Driver used in the simulations is a Scan-Speak 26W/4558T00. The enclosure selected was simply a closed box with Qtc of 0.5. Nonetheless, they gave different results.

BassBox 6 Pro suggested a box volume of 1.0 cu.ft for the target Qtc (Qtc = 0.5), whereas WinISD suggested a 2.7 cu.ft box for the same Qtc.

So, which one can be trusted?

Hello to all members of the forum, my English is not that good,so if i make some mistake fill free to lough. Now a question. After making some speakers from open bafle ,standard BR,single driver , DML and so on, i want to do somthing new to me. I have a pair of Fostex 206E drivers, and i want to put them in a front square horn. For the low end i build two BR boxes around 80L, Horn should be from 200Hz up, and for the top i have some eminence CD in horn. Problem is, im not good in all the programs that are available ,like hornresp, its very confusing for me so i need your help. Can someone just make a calculation for me, like, mouth is 70cm by 70cm, distance from the throat is ...cm. As i read somewher two sides can be flat , and two bent. I hope i dont ask too much of you smart people. I hope that i properly explained what help i need. Thanks in advance, Dejan.

Looking for a TOTL diy tube head amp with very nice parts that is warm and rich sounding. I guess something of the caliber of DNA Stratus / stellaris. Are there any schematics and plans for something like this? I do have a modded crack which I like but I want to go beyond.

I guess L0rdgwyn's Aegis guide is the closest but was thinking of something even beyond that. From the comparisons I read his amp didn't really get past even a V3 stratus.

This would be for dynamic driver cans.. 32 ohm and 300 ohm.

No specific budget but if you absolutely insist on a budget then under $10k (ideally under $5k)

Thanks!