Looking for either stuffed boards or left over kits. Kevin Carter sold these kits once upon a time.

Jim

Hey all,

Does anyone have a schematic for a US amps AX3200DE amplifier? I’m trying to work out why it’s not oscillating but I’m coming up short.

This amp came to me already worked on and it was in a mess. Ive replaced the power supply section (fets, gate resistors, driver transistors) and the output section (fets, all drive transistors) and I can’t get any oscillation at all to take place.

I’ve attached the schematic that I’m using as it is similar, but it’s missing some stuff in the output section. I’ve got all my 12V voltages, negative and positive rails, and I’ve got PWM coming into the output section but it stops right at “Q44” on the diagram that I have. “Q43” I have my PWM but it don’t go any further. Even when I inject a signal it don’t go anywhere.

I’ve replaced random diodes, resistors, and even the TL072 that feeds the PWM to the rest of the output section. What am I missing?

Bought this from a DIY member a while back and I ended up fixing the amp i had instead. these are now sold out and unobtainium from parts express!!! works great. just didn't need it after all.

$100 plus shipping

I have a pair of ESL989 which I just bought. Before buying them I heard them and they were playing fine, they were recently completely rebuilt by Electrostatic Solutions. I put them in my car, got them home, and plugged them in.

Now one of the speakers plays fine. The other powers on but there is no sound coming from them. The fuse is fine. I don’t see any destroyed components, wires seem in intact. The indicator light is blinking and I can hear the panels charging. It just seems like the audio signal isn’t getting through somehow.

does anyone have any ideas?

Thanks

Does anyone know who manufactured Motorola branded 6V6GT tubes in Canada?

Inspired by EigenTakt D-class amplifier by Bruno Putzeys and Lars Risbo,
I got very curious if it is possible to build self-oscillating DAC.
Few weeks I was struggling to understand how to implement a loop filter with proper frequency response.
It turns to be of 9th order.
I didn't read the Bruno's patents.
Understanding this official "pidgin-lawyer's" language is far beyond the scope of my intelligence.
So, I simply started playing with Bode diagrams using "trial and error" approach, playing with zeros and poles.
Than carefully transferred the result into digital domain by using Z-transform.
Fortunately, there was no problem with hardware. I used a prototype of my FPGA DAC.
Only FPGA configuration was updated.
The performance of the EigenDAC is quite impressive but still not as good as my traditional PWM-SDM.

1) Bode plot.

2) Animated THD @ 0..-100dBc.

3) Wide band 20-384k noise+distortions @ 0dBc

I have two APT preamps. Both working. The main issue...the pictures attached called "APT Holman factory mod" are my original unit I purchased in 1980. The relay was sticking on the left channel so I decided to open up the bottom cover. Please take a close look at these pictures labeled "APT Holman factory mod". The factory did the mod in 1986 or so and cut the mute relay components out and did this monstrosity. I have three brand new relays I acquired in the last 3 months. I was able to inject some Deoxit into the jump board relay and it seems to have improved. The real fix is to return this unit to its original condition and install the relay back to the PC board. I have two problems. There are three transistors. The schematic is so small and illegible that I cannot tell if they are Q17, q18 and Q19 are PNP or NPN transistors. Second problem, both 2n5087 and 2sc1345e are no longer in production. Now it looks like APT took those transistor and mounted them to the relay board in the picture. But one is a 2n3906?? I cannot read the others. I have the other preamp and those pictures are labeled "APT Holman Standard Relay" and it shows how it should be built or repaired in my view. I want to return my original unit to factory board parts and really need DIYer's advice on the best way to approach the repair. I know many of you have helped me before and I have beginner to lower intermediate skills. I have a temperature controlled soldering iron and a solder sucker. I recently recapped a Hafler DH110 so I am able to recap units if that helps. I work very slow and the unit that needs repaired have a partial wire sticking out of the board. Thanks for any advice.

Hi,

I see that often the step response is not included in the tech specification of many common brands,while I think this parameter is impotant becouse lets us know how “fast” the tweeter is and therefore if it can accurately reproduce all the details.

I have compared these misurations:

Bliesma T34A-4
https://hificompass.com/en/speakers/measurements/bliesma/bliesma-t34a-4

SB Acoustics Satori TW29TXN-B
https://hificompass.com/en/reviews/satori-tw29txn-b

and from what I see in the step response the Satori TW29TXN-B is much more faster then Bliesma T34A-4 and frankly did not expect this as I thought the Bliesma T34A-4 was superior to the Satori in this aspect as well, but apparently I was wrong.

And so maybe I should reconsider the Satori, in my next 3 way project (Woofer: Scan Speak 26W_8534G00, Midrange: SB Acoustics Satori MW16TX-8, with crossover cut 250 Hz, 2.5 Khz )

Then there would be the preference of the “relaxed” sound to consider. In the hificompass.com review:

https://hificompass.com/en/reviews/bliesma-t34a-4-34mm-alumag-dome-tweeter

they called it relaxed perhaps precisely because of its “slowness” but this is just theory.

I like to understand better if this paramenter "Step response" is important, or is perhaps something secondary.

What do you think ?

Thank you !!

Dear Members,

Where can I get the port tube for the speaker box in India, as mentioned below size?

PORT Dia: 70 mm
PORT Length: 190 mm

I tried an online search on Google but the size was not available.

Many thanks for considering my request.




Regards,

Own one of the Denafrips R2R "ladder" dacs. Also own many classic and newer CDPs with multi-bit IC dacs (TDA1541, etc) or even Delta-Sigma or Bitstream. And also have some cheap kit dacs lying around based on ESS or Philips TDA chips.
I've heard this from reviews of R2R dacs, like Denafrips and Soekris, is that while they sound warm, clean and musical, they can sound "slow", lacking rhythm and drive. And that's what I've found, even with the Denafrips oversampling mode engaged.
Could it be all those R's in the discrete R2R (Denafrips, Soekris) topology?? That it takes some time for the signal to make it through those long R2R traces. Is that what slows the music down, taking away its sense of pace and drive?

Introduction

In this post I test a new waveguide design that I came up with for the Bliesma T34B-4 Beryllium dome tweeter. The specification page for the T34B-4 can be found here. The tweeter retails for around $500 USD. I directly compare this new waveguide/tweeter combo against the RCF CD350 compression driver with the ES-800 Biradial. I chose this comparison because the RCF/ES-800 combo represents a pretty standard setup, and a good all-around performer. The RCF retails for $90 USD, and so there "should" be a considerable step up in performance with the Bliesma.

Waveguide Design Elements

I wanted a waveguide that was based on my ES-Biradial horn flare geometry so that I could control vertical and horizontal directivity independently. The biradial shape also provides closer driver spacing to the low frequency driver.

The horn is 3D printed in two components. The first component is the throat piece which closely follows the shape of surround. This requires high precision printing which is why this is a separate piece. The second piece is the horn mouth which is printed in a different axis than the first piece.













Measurements

I began by measuring the raw 2439 frequency response at 1m (see red below). I then installed a capacitor to flatten the response for further testing. I found that a 6.8uF capacitor was ideal (see red response below). The raw impedance sweep is also shown as an overlay in black.



I then conducted the same response with the RCF CD350/ES-800 Biradial combo. A 3.3uF capacitor was enough to provide a reasonably flat response.



I then measured the horizontal and vertical directivity of the T34B/2439 combo.

Horizontal coverage is characterized as a consistent and wide coverage of 120 degrees however it narrows somewhat starting at 8kHz where we see directivity at 70 degrees for the 11kHz region. Pattern control is maintained as low as 1.2kHz.



The vertical directivity is characterized as a gradual narrowing starting at 2kHz narrowing to 40 degrees at 11kHz. Overall behavior is devoid of any diffraction or spurious resonances.



I then measured the RFC CD350/ES-800 Biradial combo which provides constant directivity across the operating range. Coverage starts out at 120 degrees at 1kHz and ends at 100 degrees for the 11kHz region.



The vertical is characterized as a gradual narrowing starting at 2kHz and ending at 60 degrees coverage for the 11kHz region.



Generally we see a more optimal polar map for the ES-800 biradial. One factor contributing to this is the larger throat of the bliesma at 1.33" versus 1".

Time Domain

I then measured the Burst Decay for the Bliesma. We see a perfectly clean result within the audible band.



The CSD plot also is very commendable.



I then measured the RCF CD350/ES-800 Biradial combo. The burst decay shows some ringing in the 10kHz region out to 15 periods. Personally I like to see a clean burst decay to within 18 periods. So this is acceptable.



The CSD plot is shown as well for reference.





Distortion

I then looked at distortion using a 95dB test signal level referenced at 1m. The mic was placed at 20cm from the horn mouth. H3 and H4 measure at around 0.008% for the 2kHz region.



If we change the vertical scale to dB instead of percent, this translates into -82dB.



I then measured the RCF CD350/ES-800 Biradial combo under the same conditions and achieved 0.007% for H3 and 0.014% for H4.



Again, changing the vertical scale to dB results in H3 at -83dB and H4 at -77dB.



Conclusion on Harmonic

Both the RCF CD350 and T34B have similar harmonic distortion profiles for H3 and H4.

Intermodulation Distortion using Multiband Multitone

I then measured the IMD of the Bliesma at the same 95dB test SPL that we used for the Harmonic test. IMD is at -60dB for the 1.5kHz region increasing to -70dB for the 5kHz region. Upper treble is around -65dB.



I then tested the RCF CD350/ES-800 Biradial combo. We -64dB for the 1.5kHz region -61dB for the 5kHz region and -55dB for the upper treble.



The Bliesma seems to outperform the RCF marginally on the IMD by about +5 to +8dB dB. This may be more academic since both results are far below the threshold of audibility.

Gedlee Distortion (Gm)

Below is direct comparion using Gedlee Distortion for the 95dB test SPL. I'm using Virtins Multi-Instrument Software to conduct this test. The RCF is shown in red with the Bliesma in Blue.



Conclusions

The RCF CD350/ES-800 Biradial combo is a tough act to follow but the Bliesma pulls it off by offering a smoother response, lower distortion, and a cleaner time domain. However the larger diameter of the Bliesa introduces some narrowing of directivity in the critical upper treble where soundstage width could be compromised. The Bliesma has no trouble digging down deep into the lower midrange without sounding stressed or resonate, which is often the case when mounting a dome tweeter in a waveguide.

My subjective evaluation was brief and conducted in mono. Overall I would say that the Bliesma sounded excellent, with just a slight lack of upper treble energy compared to the RCF. Directly comparing the two revealed that the compression driver is more expressive and colorful, highlighting dynamic contrast more readily. Both had similar levels of clarity through the midrange and treble.

Could somebody please tell me what the values of this capacitor are? And any other information that can be taken from this image.
It is approximately 5mm wide and 2.5mm deep.
It is in a really tight spot so it’s hard to see the height but it’s maybe 5-7mm.
Any help is appreciated.
Thanks

Several Sony CDP's from the early 1990s received high praise from the audiophile community ... and continue to do so. The resale value of certain Sony CDPs from 1991-1994 seem to hold up ...

Login to view embedded media
What they seem to have in common is Sony's own CXD2565M 1-bit (PLM) dac chip. This was an DF+DAC device that was apparently an evolution from separate DF and DAC devices [CXD1244S, CXD2552]
In any case, the vintage 1-bit Sony dacs (or complementary DF chips) are hard to find on ebay, etc. Also, not sure what the input format is. EIAJ or I2S. I can't tell from the datasheet timing diagrams.
Sony seems to have kept a tight lid on the details and distribution of these devices -- compared to Philips, AD, Burr-Brown, that is. Not sure why Sony was overly protective of these devices?
Would be interesting to make a diy dac based on CXD2565M, maybe being fed by a USB adapter.
I have a feeling that such a project -- even if everything was very optimized and cleanly powered -- would only yield so-so sound.
Something magical and dreamlike happens when the whole OEM box -- say, classic Sony or Philips CDPs , with all those manhours of R&D -- is used. Something about the dream of totality.

Also see:

https://www.datasheetbank.com/datasheet-download/340323/1/Sony/CXD2565M?v=V2

https://pdf1.alldatasheet.com/datasheet-pdf/view/46935/SONY/CXD1244S.html
https://pdf1.alldatasheet.com/datasheet-pdf/view/47027/SONY/CXD2552.html

https://www.hifiengine.com/manual_library/sony.shtml?category=cd-player

Q835 was shorted along with open gate resistor. Removed these components to test for gate drive and there isn’t any.

When grounding Pin 1 of U800 gate drive appears. Does anybody know what U800 is monitoring? Pin 3 on U800 is at 5 volts which makes Pin 1 go high not allowing U801 to produce gate drive.

There are no shorted mosfets in output section.

Hello! I want to build my first class D amplifier. I have been reading this forum for a long time, many things are unclear, but I have already found answers to many questions. Thanks!

I'm new, hi

GlassWare Design seems to be largely sold out for the last couple years. Do we know if he is still keeping things going? Is there another source for kits/modular parts like what he sells?

I’m here because I’ve ran into quite a bite of hi end audio and diy audio that I would like help identifying and hopefully selling.

For sale Eton mid drivers from hex series and soft dome silk tweeters.Bouth in verry good condition and working order.The units are:
2x mid 5-880/25 hex
2x tweet 19SD-1 silk dome
If the buyer will I can add the nice made par enclosures with zebrano wood veneer and made of 19mm mdf.Dimensions are H-30cm,W-19cm and D-25cm,with bassreflex tunel on the back.The price for the drivers so 2x mid and 2x tweet is 200 eu including shipping inside EU.With enclosure shipping the cost for shipping are way more high,but for someone that will build some nice monitor speakers out of this drivers I think is worth,becose by carpenter you will pay such enclosures at list 250-300 eu!More info on contact!

is it as simple as connecting -V of 1st unit to the +v the 2nd unit to get ground? Thanks

pic for reference

This receiver is fairly highly regarded, it was the largest to come out of the receiver wars of the 70s, making 330w per channel. Pretty outstanding if it isn’t the prettiest girl at the dance.

It uses 6 TA7136P seven pin single opamps. Now this opamp isn’t highly regarded, not even slightly. It’s known to be a pretty poor performer. I see that there are a couple of people that sell adapter boards to where you can attach your own opamp, but at $5-$7 per adapter board I’m going to look at other options. I am currently trying to get accustomed to Kicad and EasyEDA so that I can make up my own adapter boards and order 50 for less than the cost of the 6 I would have to buy (I will share the gerber when I do).

One board is supposed to be used with the OPA604, but it’s generic pinout where they just attach the appropriate pins, V+ to V+, output to output, etc. So this board can be used with any single opamp with the same pinout like the TL071. Speaking of, I’ve also the TA7136 repalced with a TL071.

The other board that is available can be used with single opamps like the OPA604 and NE5534AP, but can also be used with dual opamps like the TL072, NE5532AP. With the dual opamps you’re just supposed to wire the two opamps in parallel, so parallel the outputs, + and - inputs and such. I still don’t know what the advantage of using a dual opamp is over a single opamp. Is wiring a dual opamp in parallel give better performance?

Until I get well enough acquainted with Kicad or EasyEDA I’m thinking I’ll just use these small adapter boards I have on hand and wire leads that go to the appropriate spots on the TA7136 pinout.



I can use standard 8 pin opamps or I could use a smaller SOIC-8 package. For standard packages I have TL072CP, NE5532AP and then the single NE5534AP. For the smaller packages I have some OPA1656IDR and then for a single option I have OPA1641AID.

Im thinking for simplicity I’ll use of the single opamp options, unless someone has a reason as to why I should go dual.

It should fairly simple, joining the correct pins.


Just omit pins 1 and 5 and remove the components on the board at 1 and 5 as stated in the photo. Also attach a 100 nF from pins 4 to pin 7, the supplies.



So my questions, any reason to use a dual opamp over a single? And do all of my choices look like they would work well? That being NE5524 and OPA1641 for the singles and NE5532, OPA1656, or TL072 for the duals?

Appreciate any and all thoughts on this.

Dan

I paid $800 for this unit used from the original owner and had good intentions of using it in my main setup, but I am constantly changing my amps and speakers that I got tired of running new sweeps each change and only used the unit for 4 months and it's been in my closet since.

I created my own phoenix adapters for balanced input and used it to run two speakers and two subwoofers. I ended up re-painting the top cover matte black because it was scratched up.

The only issue with this unit is something other users of this unit have reported having as well. If you use a fully balanced setup (input and output), the outputs 1 and 2 (only on XLR output) had some noise if you put your ear close to the speaker. I ended up just changing the settings where outputs 1 and 2 ran my subwoofers off RCA and 3 and 4 were my speakers. There are not issues using RCAS on 1 and 2 or issues with XLR input on 1 and 2.

I am asking $625 SHIPPED for it or open to trade offers for diy parts or anything else cool.

Any questions just ask. Shipping to CONUS only please.

Hi,

With the growing popularity of Class D amplifiers -> use of MOSFETs, I’m wondering about the future availability of BJT transistors. Could their production eventually decline, making them harder to find , purchase? Aside from their use in high-voltage applications and certain SMPS designs, will BJTs remain readily available?
Mainly I'm talking about Power transistors , complementary NPN-PNP parts.

Additionally, what are currently considered " the best " power transistors for output stages in audio amplifiers?
I often come across designs that feature older power transistors, so I’m curious—are there any newer options on the market?

When it comes to output transistors in audio power amplifiers, how do epitaxial planar transistors compare to triple diffused ones? Is one generally a better choice, or do the other specifications ultimately dictate the decision, regardless of the transistor type?

For instance, if two transistors share the same specifications, but one is epitaxial planar and the other is triple diffused, which would you choose? Would there be any noticeable difference in sound quality or performance? From what I’ve read, epitaxial planar transistors tend to be faster and more linear, while triple diffused transistors are more rugged with higher current and voltage ratings.

- Bruno.

$200 plus shipping to wherever you are.

1 pair of Lii Audio F-12 full range drivers. Used briefly in a temporary baffle for approximately 100 hours. They sounded great, but were too big for my listening space. These will ship in the original packaging. These are also posted on US Audiomart.

Hi everyone hope everyone is doing great.

I acquired this DAC and looking for a popping solution.
The right channel will pop whenever audio starts playing. It can be replicated by either play/pause or turning volume up from 0.


There are a pair of CHAMP Modules (pictured, horizontal with many LEDs) which I assumed was the cause. After swapping the cards the popping did not swap so it could be up stream.

The three boards (vertical) are Decoder board, Digital Filter board, and DAC board.


The dac uses 4 PCM1704 chips.

No service manuals are available and information is sparse.

Aside from the popping and slightly higher noise floor compared to modern DACs, it sounds great. I use it for my tv as well so the pops between quiet passages doesn’t sound great.

Ps; this dac has a quirk of never turning off. When you press the front power button everything stays lit but the input/output relays are disengaged. I assume they’re subscribed to the idea of leaving your equipment turned on makes it sound better.

I have two single extension cabs with a 10" 8ohm speaker each. Would the following doodled diagram work if I wanted to run one into the other as either series or parallel? I have amps that are 4 or 8 ohms only as well as a few that are selectable between 4,8, and 16 ohms so it would be nice to have it as versatile as possible. So the three jacks (in, series out and parallel out) on one cab and just a single jack on the second cab.

Edit:replaced crappy doodle. 🙄

For sale a quad of verry good hifi amp fuses 16A and 6.3 x 32 mm big.Used but in top condition.Price of new is 32 euro a piece.
I sell for 60 euro including shipping inside EU.

Hello,

My name is Robby and i live in Montgomery, AL. i have many different stereo components, mostly vintage integrated SS amps and many different types of speakers. Looking for more information on tube amplifiers, especially one that i picked up used. i will ask for help in a new thread. Thanks for all the great information on this forum. i am a tube amp novice. Looking forward to learning more.

Thanks,
Robby

Bought this from an estate sale a few years ago. opened only to figure out what it was. all parts are there and 100% brand new old stock!!!! OH the joy of building your very own HEATHKIT!!!

Super cool!

$125 plus shipping
***NOTE: the last picture showing the built unit is a photo i found on the web so you would know what it would look like.

Hello all, reading and building a lot of designs here from the forum. I want to share some of my experiences in the future. I can draw my own schematics and PCB's. I have also a nice workshop where I can 3D print and solder my projects. My skills are with tubes, through hole and SMD designs. I appreciate the knowledge here on the forum. Some favourit members are Abraxalito, Mooly, Jan.Didden, MarcelvdG, Krivium, b_force and Kevinkr.

Projects from the past,

• 1541 DAC
• TDA1383 DAC
• PCM1792 DAC
• ES9038Q2M DAC
• Tube phone preamp phonodude
• Hybrid phone preamp
• Passive preamp with remote and source select.
• SE 813 Tube amp
• Several Hypex UCD and Ncore amps.
• Purifi 1et400a amp with and without (tube) preamp.
• JBL/Eminence loudspeakers.
• JL Audio subwoofer.
• A lot of power supplies.
• Rebuild Thorens TD160 mk2 turntable.
• Tube preamps with 6n6p/ecc99.
• 6 x LM3886 composite amp.
• 2 x LM3886 composite amp.

Ronald

SOLD

Posted some time ago to sell some spare blank boards but there was no interests.
So i went ahead to purchase parts to populate and tested.
Info on the boards :
https://www.diyaudio.com/community/threads/lt4320-based-active-rectifier.336572/page-78#post-7729619
All the parts are smd devices, hand soldered by me meticulously. Boards are cleaned with IPA to make sure there is no residual flux left behind.
MOSFETs used are TPH4R008NH, which is one of those listed by Prasi
https://www.mouser.sg/ProductDetail/Toshiba/TPH4R008NHL1Q?qs=sA3qAAQcQeEIWvkYMlVV6Q==

I have not installed the LED, which i deem as redundant. C1 and C2 are also skipped, which i feel is unnecessary unless the rectifier is wire over a long length to the filter caps. Some well-experienced member has also reflected that the caps on board is not really necessary.

The pair of boards + shipping to you ( registered + tracking) = USD 50
Paypal FF only please.

Hi to all,

I plan to build a three way in a simplified form of Watt Puppy. I don't want to try to replicate it.

My question is should I use two 8 inch woofers or one 10 inch. We often say that there is no replacement for displacement. Also I beleive that a pair of 8 inchers will not sound the same as one 10. Even if the 8 inch pair has more displacement than the 10 inch by approx 30%. I aim to have deep yes but mainly articulate bass. On the downside, that a 10 inch facing driver is quite big visually (not to mention a 12 incher).

I have not chosen the other drivers yet. But I want top tier stuff!

Thanks for sharing your experiences,

Walter

Hello all, i just bought Sansui AU-D33 already recapped. im still in progress checking all caps one by one.

I found that in lC2 0.47uF/100 prev owner replaced it with 0.47/50 ?
Located in F-3592 Protector Board (l)

And if i must found replacement, i cannot find Ecap with 100v, most of them is MKP or MKT or worst case i must buy pink WIMA. (worst at price side 😆 )

That is so far my question, i will add more question if im confused.

Thank you so much

Hey all. I am new to the site and newish to servicing Class H Crowns (DSi, CDi,XTi). I work in digital cinema service and got into fixing Crowns as an extension of the service. I am hoping to get advice on more advanced servicing of these crazy amps (very complex) and pass along any info I might have on audio (Dolby certified in ATMOS design and set up) and Crown repair, or anything other related stuff.
Matt

Hi selling a stereomour ii set for 240 V with shunt reg mod and upgrades as:
4x Vcap odam + khozmo 48 steps attenuator. (only those cost approx 650 Eur)
The price I list is for the working unit only without tubes! As you can see painting has some defects. The unit works perfectly of course with its hum reducer pot.

If you want I can add tubes of your choice. Shopping can be as follow
2a3 Linlai mesh or linlai candle type titanium or cheaper ken rad

12at7 can be mullard or others of your choice between my collection.

Price demanded of the unit without tubes 900 eur+shipping obo. If you want tubes as well we can sort out a great deal.
Prefer to ship to Europe to avoid insane ship costs for far away destinations
Any question just ask
Fair offer will be accepted

Hey guys, I’m looking for a pair of 2A3 tubes. They don’t have to be new, used but in good working order would be OK.

Just looking for something affordable, can be original American tubes, or Russian, Doesn’t matter.

let me know if you have anything available.

Thanks in advance!

-mac

Matched pair and messured top NOS tubes with verry good sound.Never used. Price would be 100 euro plus 9,80 euro shipping inside EU. Payment by paypal for friends.

Hi, I am audio and diy enthusiast from Montenegro! There is one big flea market here where people bring awesome stuff, and I love to 'save' things from there for ridiculous prices!

Since I don't see myself hauling batteries to get an A class amplifier playing I was wondering about a PSU for the Hiraga monster.
I've seen them without input chokes and with. I believe the Lundahl 2733 was mentioned, also the 159ZG Hammond. This came about in an older thread but since I'm a beginner the discussion was a bit all over making it very hard to follow. From what I read the input choke is the better option for this amplifier since it can deliver large amount of current very fast. So maybe someone could shed some light on this and maybe a schematic. I think the discussion was also in l'audiophile magzine about the PSU for the 20W and they somehow changed it to have a choke in it but I couldn't find it for the life of me.

Good day ! I have been working on a Monster Clarity HD1 multimedia speaker which has this HYS3C210-CS smps. Its is a very good monitor speaker but suddenly stopped. I found 2 diodes Sb260 and Sb160 shorted. I replaced them but still it is not working. At the back of the board as I believed is a driver chip and a ceramic capacitor encircled with red which are defective as shown on the photos. Can anyone share me the number and value of this SMD parts? I would appreciate much if somebody can also share me the schematic diagram of this SMPS. Thank you in advance bro. More power!

Hi there, I recently got an old preamp that came out of a P bass special from 1983. I placed it into a 5 string bass that I built and it sounds good and very quiet. I used Seymour Duncan quarter pounder Jazz bass pickups which are much hotter than the original P bass pickups from Fender. The only problem that I have is that it has got a boomy bass sound. Obviously the preamp was designed for a four string bass and not for a five string bass. Now, I can help myself with a soldering iron. but I am not an electronic expert by any means. I have got a copy of the schematic of the preamp and would like some help from you guys. I'm sure there's a way to change one or two components to reduce the gain of the bass frequency, maybe smaller caps or resistors but you guys must tell me which. Any help would be appreciated. Thanx.

Unique calibration file is included

Located in Ireland
Can ship anywhere.

SOLD

One thing I can't get my head around;

Why can a single driver based car sub can be heard clearly approaching from the next block and outdoor concert bass cant be heard in the car park? What makes a single low efficiency car 12" inna 35L ported box render basslines clearly inside a mall from the car park?

Hello everyone,

I want to add an ambient rear-firing dome tweeter to a pair of 3-way speakers to observe the effects.
The system is powered by a Hypex FA253. I will use the 100W inbuilt tweeter amplifier to power both the front-firing LT3.2 Planar ribbon plus the new rear-firing ND16FA6 dome.

I am aware that the filters and slopes (DSP) for the front tweeter will inherently be applied to this ambient tweeter (being connected to the same processing). However, I intend only to use the rear-firing dome from ~8Khz and up (I am after ambience / highest octaves only). I might add a 3.3 µF cap for a 1st order roll-off at 8000hz to the ND16FA6?

What are your thoughts on this? I would appreciate any help on how to wire this up; I want to ensure the load to the amp is stable, the impendence stays happy etc.

Thank you kindly.

Vance

Howdy, looking forward to chatting. Longtime diy'er and audio enthusiast for decades.

Hi all, I am here as I had a work friend who was a very keen DIY audio guy and was building some of the Nelson Pass Burning Amps when he got sick and was unable to continue due to physical ill health. I helped with the builds while he provided direction and brain power. Unfortunately he died before we could finish, I got the two chassis assembled and PSUs built and tested and we were waiting on a few parts, but his illness progressed very fast.

Anyway in his memory I want to finish what we started albeit in slightly altered and reduced form (was originally planned on balanced mono-blocks with a lot of FETs). I have a background in electronics as used to be a tech decades ago, but not anything to do amplifiers, however have been reading lots on this forum and learning a lot - didn't know what a Class A amp was, or terms such as mono-block or gain stage or anything much else a few months ago, this site is a terrific resource!

Thanks

Would the Coral 1OL-24 be a suitable driver (bass/mid) for a dabble into Open Baffle? Can’t seem to find much on its specs. Thanks.

Price drop
AMP Balanced/unbalanced TPA3251 & TPA3255 AUD45.00
PSU AUD30.00. Family and friend PayPal

Yes I will post anywhere AuPost delivers and yes I will charge insurance and the cost of the box and there are no returns.

Photos for illustrative purposes.

I have sold some, so check out what I have left.

If I get no response by 12:00 Central Australian time on 2024-08-28 they go in the bin. I have had enough and I really do not care.

Hi , sadly I accidentally spilled a bottle of water ( was on the desk , right next to the amplifier , yes , very good place to keep it ..... ) went into my Amplifier ( music was playing. suddenly died ). It went on the amplifier section. ( output transistors, heatsink. )
I cleaned it , let it dry.
amp does not turn on , power transformer seems ok ( 4 ohm 14 Henry ). Fuse is ok, maybe something else , not even stand by led works.
Measured power transistors show a few ohms, so most likely they might be blown. Until I take it apart and measure.

Output transistors are 2sc3182n / 2sa1265n . Only place I found them , and I have my doubts they are original and not fake.
https://www.adelaida.ro/2sc3182n.html
https://www.adelaida.ro/2sa1265-si-p-140v-10a.html
Bought components from this website before, they were genuine.

*Question is , for testing I think I can use 2sc4468 / 2sa1695.
What better alternatives are ( to use permanently ) instead of the original 2sc3182n / 2sa1265n .
Would 2sc4468 / 2sa1695 work ? they are 20mhz instead of 30, same Ic , power.
250p instead of 220p .
Slightly different Collector-emitter saturation voltage , Collector cut-off current , Emitter cut-off current . Specs I don't really understand.
Datasheets:
2sc3182n
2sc4468

I hope the pre drivers and drivers 2sc3298 / 2sa1306 are alive. Tho I found them too
https://www.adelaida.ro/2sc3298y.html
https://www.adelaida.ro/2sa1306-si-n-160v-1.5a-pioneer.html


* Amplifier is my beloved Pioneer A702r
Service manual down here in attachements.

Weird that no water went on the power supply side. amp just turned off ( died ) won't turn on , not even in stand by at all.
I know water and electronics aren't friends, but tap water , no salt, could cause that much damage !?.
Amp was running pretty high volume, hot ( 27 degrees celsius ambiet temp , yea it's pretty hot here in the summer ) . Temps were around 50c.

So I think I need to take it apart, test the stand by, main transformers separately. Check the output transistors, drivers, pre drivers... etc.
**** I just checked quickly the cable that goes from the main transformer to the amplifier power section +- 55v dc , unplugged, on the amp side it shows 0.5ohm so yea, something is fried.

- " same amp " slightly less power ( a602r ) uses 2sc3281 / 2sa1302 only 4 transistors , two per channel. here on a702r are 8 transistors, 4 per channel but 2sc3182/2sa1265.
are MJL3281A / MJL1302A some kind of replacements for 2sc3281 / 2sa1302 ?. What if I use MJL3281A / MJL1302A instead of the 2sc3182/2sa1265.

- Bruno.

Hi everybody. I’m here cuz I just bought a cd player, Sharp DX 200, for 5 bucks and one output is really quiet. Everything else seems to work. I’ve tested and ruled out the other components of my system and am certain that the fault is with the player itself. I have another cd player that works fine when hooked up. I resoldered the output Jack, then I replaced it. No change. The left output is good. The right is barely audible. I can’t find the schematics, and even if I had them, I’m not that great at reading them. I suspect it might be a simple repair. I already have a working cd player but want to do this as a fun/learning project. Looking for some help. Thanks in advance!

As an owner of a Marantz PM80SE, it has given me the usual grief of a failing STK3102, twice.

Thanks to this forum, I quickly found it to be the culprit when it first statrted acting up in 2004. And then it started all over again in 2011.
Not wanting to replace the module I again, I thought about making a discrete replacement based on the VAS of PM8000, which looked like it should work without too much headaches. But I stashed the amp in the attick instead and never made an attempt.

After some work on my brothers PM7200KI, I thought to have another go again.

Powered it up and sure enough, the output relays refused to engage.
A quick measurement on the headphone voltage divider near the red reed relay at the back of the power amp board confirmed the left output going close to a voltage rail.
Took out the STK3102 (or so I thought) and powered it up again, no more DC.

Since the replacement STK-module that I bought in 2004 was no longer functioning properly, I popped the plastic cover and found that it was a fake. Finding only SOT23 transistors and some 0805 resistors, I was a bit surprised. Okay, in a VAS it worked for about 6 years, but aren't these things supposed to be able to drive 8 Ohm loads?

This is apparently the inside of an oriniginal:


Whereas in my (supposedly) STK3152 replacement it looked like this:


Front of the fake:


Rear of the fake:


No doubt many of you know about these replacements being fake, but I thought I'd share it anyway.

I do wonder, though, if I can repair this thing and stick it back in...
Hopefully these transistors aren't some Chinese knock-offs but generic transistors that I can find in a smd-codebook..

I have 2 M2 clones built with Tea Bags boards. I connected the first M2 I built which had been sitting unpowered for about one year and noticed a greatly diminished output from the left channel. Both Q1 and Q2 are heating up but I did notice that Q1 is running about 10F lower in temperature than the right channel which produces the correct output. I poked around on the board looking for a bad solder joint with no luck. I replaced the problem M2 with a second M2 and confirmed the issue is isolated to the left channel board. Power supply voltages are fine. The only thing that changed was I did remove the fender washers compressing Q1 and Q2 to verify the FETs make and model. Is it possible I damaged one of the FETs doing this? Any help isolating the problem is appreciated. Both of my amps have operated flawlessly since I built a few years ago.

Jim

Hi, I've tried to read through the posts on options for building a sub with the 3015LF driver, but I'm curious if I'm missing anything (I assume I am).
Designs that I'm considering are Cubo 15, Cubo Sub, SS15, and (maybe) THAM15 (not sure if the 315LF works in THAM15).
I have 4 of the drivers already in 4 40-year old TOA bass reflex cabs. I'm assuming there's some better cabs around now. The TOA cabs only go to 50 Hz. It'd be nice to get to 40. I use these primarily for small, free outdoor parties, playing everything from acoustic music to tekno.

WinPCD - Passive Crossover Designer for Windows with Polar plots

An update is available for WinPCD, the Windows Passive Crossover Designer, a crossover program that originally emulated the PCD that was written for Excel. It still doesn't do all that the PCD does, but it has other enhancements and does not require Excel.

Prior to this release (v1.513) the user interface locked up when the polar calculations were being made. No windows could be opened or moved, even the polar window would accept no user input. There was a single thread.

With this release the user can now open, move or close windows to include the polar plot window. Controls that affect the calculations cannot be changed, however, because this would interfere with the polar plot calculations. The polar plot window can be closed prematurely and the settings will all reset to what they were before calling the polar plot.

While coding these changes I noticed that there was some error in the off-axis response. The farther off-axis the mic angle, the more error occurred in the calculations. That has been corrected and I think that the off-axis calculations are now accurate. Keep in mind, however, that the off-axis has two components, the change in delay from each driver due to different distance and the change in each driver due to the off-axis response change. The latter is a calculated change based on the basic assumption of a flat radiator. It's not accurate (and possibly worse than reality), but it provides a basic idea of the change with angle.

Dave

Hello all,

I'm living in Richmond Hill, and hoping to dive deeper into my home audio set up.

The biggest part of my journey, a pair of Klipsh Klipshorns KC-BR (from the late 80s or early 90s) that I inherited from my father. Ever since I was a little child I was absolutely obsessed with them and in beyond happy that I now have them in my possession.

What I'm hoping to gain here is some info on how I can bring them back to glory (everything is original so I feel like many parts/wires maybe due for some upgrading), and also how I can integrate them with an appropriate set up. I have read on some other forums that there may be some kits that can be purchased to help do this, however I never got a working link to any. They are in pretty good shape physically, however I would want to update the mesh around them, as they have taken some hits after being moved from a few different houses over the years (some rips and degrading of material). The speakers are currently set up in my basement (in the corners of the room), but not connected to anything. So that's one of the big things for me is to make sure I get, or build, the correct things to paid with the system. Such as amps, equalizers, ect. If there's anyone local to the area that can help or give advice, I would be SO THANKFUL for that.

I used to think of myself as a little bit of an audiophile, but a quick read at the posts on here and I realize that there's a lot that I know nothing about.

The last thing I want to mention is that I would like to get the system integrated with some newer tools. I have a simple pioneer sb3 dj set paired with 5" JBL 305P Bookshelf Speakers. Unfortunately neither of them are being used at the moment, but the hope for me is that I'd be able to sometimes use the khorns to play some music when people come over using the sb3, and at other times to just use the bookshelf speakers with the sp3 when just messing around myself. I do have a small collection of older vinyls as well (maybe 300 or so albums/singles) and I would like to be able to play those on the khorns as well.

Thanks in advance

SS15MOD - TH 15" flat response

Hello all,

Time to post some results, but before, I'd like to say thanks to all guys who have been supporting / teaching / encouraging me to learn more about TH design.

After some benchmark between lots of different cab I decided to choose TH one due to the large documentation available for design but also due to good results between simulation and real worlds.

The base design is the SS15 published by Jbell (He has one sheet build constrain, I'm not 😀 )

Single sheet TH challenge

or TH18 published by Xoc1 (designed for 18" drivers based on Danley's design TH118 that is also based on previous 15" design TH115)

TH-18 Flat to 35hz! (Xoc1's design)

They have the same base design in terms of fold.

Project targets:

Low frequency <40Hz for a single cab
High frequency > 100Hz
Volume < 300 L (reduced from 450L once my current T18 clone cab has 300L with 18” driver and I swapped from 18" to 15")
Single driver
SPL@1m > 98dB

I chose Brazilian driver Snake HPX2150 15” and I also forgot about 18” once I confirmed I could reach my target with 15” one with more compacted size.

Bellow you can find Thielle/Small parameters in comparison with SS15’s driver (Eminence) and also THAM15’s driver (B&C):



The design was started using the image below to find the best targets for the cab.



The S1 is a results of driver compression ratio (cone area dived by throat area).
Detail about the others parameters see here (credits to soho54):

Hornresp for Dum... hmm... Everyone 😉 - Page 2 - Home Theater Forum and Systems - HomeTheaterShack.com

Like a DOE (design of experiments) I covered the ranged bellow:

Compression ratio: 1:1 till 2,5:1
Note: I didn’t went higher once the driver isn’t stiff enough and the motor strength (BL^2/Re) isn’t that high too.
Horn Length: 250cm till 350cm
Horn expansion angle: 0 degree till 5 degree

The best option I found was:

Compression ratio 2:1
Horn Length: 260cm
Horn expansion angle: 3 degree

Hornresp parameter for base design.
S1: 440 L12: 20 S2: 493,68 L23: 100 S3: 760,92 L34: 120 S4: 1081,71 L45: 20 S5: 1134,75

The next step was to install Solidworks to build the cab thru automatic folding process using parametric sketch.



In sequence I also implement an automatic unfolding process. This is very important to guarantee reliability on the hornresp simulation. I used soho54 method that is called “advanced centerline method”.



Using parametric CAD software makes things easier when they are well implemented.

Next, I tryed to add the second horn expansion:

Horn expansion angle: from 3 degree till 24 degree.




The best results condifering 2nd expansion was: 6 degree and 12 degree

Here are my proposals:

Proposal A (HxDxW 762 x 630 x 550 = 264,5L)



Proposal B (HxDxW 776 x 625 x 550 = 267,1L)



Proposals A and B over righted @ 600W



Which one would you guys pick up to build?

Im here because of a project with emulating the soundbar bluetooth signal to my JBL SB400 subwoofer with a Raspberry pi + shairport-sync 🙂
im running shairport signal today with one system connected, and it is working flawlessly 🙂

Hello, greetings to all members here! I'm an electrical and sound engineer from Hungary.
My hobby is designing and building all kinds of analog audio electronics.

As a first topic, I'd like to learn more about the sensitivity measurements of the speakers.
Especially, the measurement method(s) for tweeters.
I've got a Dayton DATS V3 system, and I've tried to use it for woofers or for midrange speakers, with the added mass method. It's easy and working fine for me.
But unfortunately, this isn't suitable for the majority of the tweeters (especially for the more delicate silk or other soft-dome ones).
I've also tried to measure that via a test-box method with a known internal volume.
Unfortunately again, DATS always gives me an error-message, regarding to the volume of the test box (it's either too large, or too small at the other attempt, it's annoying and strange...).
I've also read somwhere here in the forum, that if the TS-parameters of the driver has been measured, then the WINISD for example can calculate the sensitivity somehow... Sadly, I don't know the exact formula, how to get that.
I've also read about the miking method, when you put a mesurement mic in front of the speaker (in axis, 1m away) and put 1W of output power (or 2,83V when the impedance is 8 ohms) to it, and measure the SPL with a calibrated chain... something like that...

So, my question is... what's the best way to do it, with adequate accuracy but in the simplest way...?

Hello, I'm new to the forum. I'm here because I'm designing a channel strip for a project, and I plan to include both tube-based and solid-state preamplification stages. However, I have several questions about the designs that I would like to resolve. Thank you.

Hello all!

I'm a student currently at the end of their bachelors program in Music Technology and Audio Production. I also work professionally as a sound engineer.

I know a fair bit about electronics, acoustics and math already, but am by no means an expert. Live sound systems and their applications/variations are my current area of expertise (as far as that goes).

I've joined this forum as a way to learn more about speakers and their designs to serve as a reference for my journey to building my own set of speakers. I know there are kits available and while those seem like a lot of fun, and I will still probably build some along the way, my primary goal is to research and develop my own (maybe not very unique) speakers for my personal use.

I look forward to participating in and hopefully contributing to discussions on here! 🙂

Hi every one
I have JL e6450 the number Q50(irfz44r) and Q49 (irfz44r) was barn i order some from AliExpress and change it but still same problem its going hot, with out connect the speaker.
as will the voltage when i reed it from the amp its give me 6.40V in the meter
any idea what is the issue
thank you for your help

Hi All,

I'm just about to start a Push Pull Amp build using E130L Tubes, it will be a dual mono in one enclosure, output transformers are being custom built in Poland, input impedance 1.6k, phase splitters will be 6n6p's, grid v regs will be 0A2 gas tubes, the plan is for 50/60 watts into 4/8 ohms. This is my first Power Amp build, so any advice help on this would be appreciated. Everything I need is ordered, I've probably forgotten something.

Hi everyone!

I've had several vitage tube amps and modified them but I'm not at the range of expertise to evaluate every aspect of them. Since SMPS are available (please disregard tha tin the discussion, I've got several analog and digital PS available), the major factor in cost is the output transformer. They are (compared to other transformers) very expensive, and I'm aware the saturation is a big issue, my question is, why not use regularily available ones? I have to admit, I am not aware what transformation values are exactly needed nor do I know about the typical inductance of sait OT.

Capable and reputable OT (~40-100W) come at 150-400€, but here's my question, if you can get 100V audio transformers for as low as 2,50€ (in bulk even cheaper), isn't it possible to buy a bunch of these and compensate for the current by parallel/serial connect them? Probably counter inductance by R-C or other circuits? I mean, for 400€ you could get ~160+ of them.
Please don't laugh about that, I'm often able to tell what's a problem in an amplifier circuit but regarding tubes I've got little practical experience in output transformers and what's really required or the 'usual range' of output transformers.

So my question is, (besides saturation), what's the problem of mass parallel/serial 70/100V transformers and why it isn't there any example on the net for it (or rebunking it) since it could shave the cost down to about 1/10s? I know, that it's probably looking at it very naively but I haven't found any reputable stance on it.

For those so interested, a recent build from scratch of the Voigt Corner Horn is chronicled here:

retro vintage modern hi-fi: Secrets of the Voigt Speaker - By Peter Skinner

PNW dad and electrician here. Loved good sound since the mid-‘90s. Currently rocking a pair of Bagby-designed Helix MTMs. Love to learn more about DIY.

I am selling Seas E0047-04 T29MF001 tweeters in perfect working order as they are still running.
After trying everything for me it is the best tweeter I have ever had, everything sounds good so it is easy to filter passively or active,
It took me a long time to get them since seas has not manufactured them for a few years.

Price €450+shipping

http://www.seas.no/index.php?option...&id=372:e0047-04-t29mf001&catid=25&Itemid=254


The T29MF001, “MAGNUM” is a 25mm magnesium dome tweeter with a patented Neodymium based magnet system. It is the tweeter of choice for those who seek extremely precise and realistic sound reproduction combined with a relatively low crossover frequency.

A unique HEXADYM patented magnet system based on 6 radially magnetized NdFeB magnet blocks. Efficient ventilation and damping of every potentially resonant cavity behind the dome, surround and voice coil. Moderate magnetic stray fields present no problems in AV installations.

A generously underhung voice coil ( + and - 0.5mm ) ensures low distortion even with low crossover frequencies.

An optimally shaped magnesium dome membrane which behaves like a piston throughout the audible frequency range and shows a controlled break up above it.

A homogenous, linear surround manufactured by SEAS from SONOMAX, a soft polymer material of high climatic stability.

Flexible lead-out wires which ensure a good connection between voice coil and terminals. This arrangement also helps to prevent lead breakage due to the large excursions encountered when low crossover frequencies are used.

Low viscosity magnetic fluid which provides excellent cooling while maintaining a low resonance frequency.

6,0 mm machined aluminium front plate with a moderate horn loading characteristic which ensures linear frequency response, and a stiff and stable connection to the cabinet.

A substantial injection-moulded rear chamber made from zink eliminates unwanted chamber wall resonances and conducts heat away from the magnet system.

Now that kids are nearly out of the house, I’ve had the opportunity to focus back on to my lowly home studio. In my college years, I always enjoyed the Parasound power amps designed by John Curl and a recent find at a used record store got me into rebuilding an old HCA1500a with some swollen caps. That amp is working great now and I’m back for more looking at rebuilding other malfunctioning gear I come across.

I’ve already read so much on diyaudio and know there’s so much more information out there for me to read. With an account now, the conversations can be two-way. 🙂

Ben

Hello everyone. Years ago, I bought an NHT Power2 with two 500A modules powered by a third 500ASP module. I always wanted to add a 1000w power supply but never did. I just noticed that Icepower released a stand-alone 1000s module that I could use. Does anyone have any experience with them? I have opened the case before, and it seems like there is enough room to add the 1000S, use it to power both of the 500A modules and then create a 3rd channel using the 500ASP. Thoughts?

Hi there!

I'm interested in DIY audio stuff and have already build some speakers. Started with some speaker kits and ended (so far) with two self made active speakers.

So cheers to everyone 🙂

Hi All,

I have Krell KRC preamplifier and try to find more technical information about it. I tried to find a service manual or some circuit but unsuccessfully. Does someone have more info about it. All capacitors has been replaced and it sounds great. The bad thing here is that the preamp cannot be switch off from the device, The only way is the turn off is from the power socket. I digged a little bit looking the board and found out there are two relayes which should be used for switch off/on the preamp but they are not used at the moment. That why I am looking for some circuit because I want to make it workable. They may be used when there is some issue with the device but who knows.

Any help will be usefull,
Thank you in advance.

For sale.
As good as new. Bought about 3 weeks ago from Audiophonics. I was under the imression that my older was not working anymore. That was not the case.
So i don't need it anymore.

65 euro excl. shipping. Pics wil follow.

I have for sale this R2R DAC with transformer output bal/se chiurutu.
I am asking 100 € with shipping (registered)included in Europe.

Hello,

A few days ago a good friend of mine asked me for help. He wanted to utilize his guitar effect pedals with vocal microphone at stage.
After short research I found that off the shelf solutions (like Radial Voco-Loco for example) aren't so affordable, so I came with idea doing it DIY way.

Basically I wanted balanced XLR microphone input, single ended 6.3mm send/return and balanced XLR line level output.
Design assumptions:
- Lowest noise and distortion possible
- Gain range suitable for both dynamic and condenser microphones
- Switchable +48V Phantom power supply
- Universal and easy to use
- Reliable
- Compact, fitting inside Hammond 1590BB enclosure
- Rather simple and elegant circuit as I don't like to make things over-complicated
- Not too expensive

Later, after hearing friend's suggestions:
- Possibility to bypass effects with foot-switch
- Dry/Wet (blend) mix

Considering the following I decided to use ICs from THAT Corp. - 1510 as mic pre and 1646 as balanced line driver. Both could be substituted with slightly worse INA217 & DRV135 from Texas Instruments.

Dry/Wet mixing circuit is rather simple, virtual ground type.
I could have used one dual pot instead of two singles but that way gives more flexibility.
If I'm not mistaken now it is possible to use it as two channel mixer - using mic input and return jack as second channel.
Two inverting op amp stages are used so absolute polarity is preserved.
Only thing I'm not completely sure is if should I leave it as is with buffered pot or place pot in place of feedback resistor, getting more gain possibilities.
OPA1678 input bias current is extremely low so coupling cap isn't probably required.

Power supply design was definitely the hardest part of design process. More on this can be found at my another thread - https://www.diyaudio.com/forums/pow...-getting-15v-15v-48v-single-power-supply.html
Phantom power and grounding are really tricky matters. I had to did a lot of research in terms of proper grounding and "Pin 1 problem".
Some really helpful papers:
Ian Thompson-Bell - Mixer Grounding 101
Rane note 151 - Grounding and Shielding Audio Devices
Rane note 165 - Pin 1 Revisited

After a lot of thinking and with help of fellow forum users I finally decided that I gonna use external +48V SMPS and integrated DC/DC converter to +/- 15V.
My last concern if its ok to "tie" enclosure and signal grounds with LED and resistor when SW1 turns phantom off. Or maybe DPDT switch should be used?

There is a jumper, so I have a bit of flexibility with grounding. Depending on the results of measurements, I can tie grounds or leave them unconnected.
Most sources recommends tieing them in one point. But isolated DC/DC converters are pretty new thing, maybe they didn't been considered? Having completely floating supply sounds indeed interesting.

Schematics are attached to post. Now fun part begins - PCB layout 😀

Regards,
Miłosz

I'm Tony Ferraro, and I'm excited to join the diyAudio community! I know a lot about recording and I know how to setup and use complicated professional audio equipment, but I know very little about circuit design as a whole. I can troubleshoot and fix most audio related gear, but would like to learn so much more. I want to understand how circuits are designed, how components work, why components are chosen for certain designs and how they affect the signal in a circuit. I want to be able to backwards engineer any circuit and be able to make a schematic on my own. Eventually, I want to design and fabricate circuits for custom audio projects.

22 years professional experience working as a recording/live sound engineer, record producer, drummer/musician, vinyl scratch DJ, etc. I've always had a passion for music and am always curious about how things work. I got much more interested in diy audio when I had $4000 microphone pre-amps and other gear in my studio would malfunction and needed service. I couldn't afford to pay or wait to get these things fixed. I slowly started to figure out how to do it myself. After a while, people started asking if I could fix their gear and made some decent cash doing it. To make a long story short, a large portion of my income comes from repairing, servicing and selling audio equipment. It's hard to say I actually know how electronics work, but I end up figuring out whats wrong and doing the repairs myself.

I think I have the unique ability to answer a lot of questions from a different, but very useful perspective. I am more than happy to share my knowledge and am glad I have somewhere to post questions and get help troubleshooting projects I'm working on.

About me about my background-

I started my career obtaining a degree in Recording and Engineering at Music Tech College of Music in St. Paul, MN. My professors noticed I had a good ear as I quickly earned a solid reputation for many established musicians in the Twin Cities music scene. I ended up spending 12 hrs a day at school, taking advantage of free studio time recording local musicians using world class recording gear.

I was fortunate to learn how to record music using the best equipment while I went to school, but soon after found myself struggling to make anything sound half-way decent, recording death metal bands in a drywall dungeon practice space where I had to battle sound bleed from multiple other bands and mixing on headphones using extremely primitive physical (large and heavy) DAWs and shitty microphones. 2003 was a terrible time for digital recordings. Everything sounded bad, everything took forever, nothing worked right and computers would crash a lot. I somehow had a reputation with respected national recording artists that had a high standard for quality.

I don't know if any of this info is useful to anyone else. I might add to this later...

What is the purpose of using 200uf and L2? What do these do? What is the effect?
And what was 0,47 ohm used for ? can you help me.

This is a speaker system that I completed earlier this year.

Goal: A line array with efficiency of about 100dB 1W/1M not weighing more than about 50 pounds and is not too large so that it can be easily set-up and stored. The speaker system is intended to be driven by a class D amp powered by a 12V rechargeable battery rated 12AH.

A. One horn tweeter and six 5.25 inch woofers. This is a two-way closed-box system with a crossover frequency of 2 kHz.

1. The width of the enclosure equals 7.75 inches. For this width and where Fstep equals the baffle step frequency,
Fstep = (4560 in./ 7.75 in.) = 588 Hz
Thus the tweeter functioning at freq. > 2 kHz has efficiency in its operating frequency range equal to its rated efficiency of 100 dB 1W/1M.

2. Efficiency of each of the six woofers is specified as 89 dB 1W/1M. As a result of driving the six woofers together,
efficiency gain = 10*Log(6) = 7.8 dB
(Thanks to James R. Griffin, PH.D for this equation)
Thus efficiency of the six woofers driven together equals 97 dB 1W/1M. -only 3 dB away from efficiency of the tweeter!

B. Line Array
1. Center-to-center spacing of the woofers mostly equals 6.5 inches. This means that the woofers can function as a line array for freq. < 2 kHz. This is given that wavelength at 2 kHz equals 6.5 inches. Two of the woofers and the tweeter are positioned on the baffle in the D'Appolito MTM arrangement.

2. For the line array, intensity decreases at 3 dB and 6 dB per doubling of distance for respectively near and far field reproduction. Where d equals the distance at which the transition from near to far field reproduction occurs or the critical distance,
d = 1.5*f*H^2 (Griffin)
where f= frequency in kHz and H is the height of the array in meters.

3. Listener distance from the array is made equal to 2 meters to facilitate the listener being in the near field reproduction by the array as much as possible. Because I wanted the speaker to be easily moved, I limited the number of woofers to six, and the resultant height of the array between the radiation axes of the top and bottom woofers equals 1 meter. Given critical distance d equals 2 meters, height of the array equals 1 meter, and solving for frequency in the previous equation,
f = d/(1.5*H^2)
= 2/(1.5*1)
=1.3 kHz
This means that the listener is in the near field reproduction of the line array where freq. > 1.3 kHz. This is less than an octave below the crossover frequency of 2 kHz.

C. Equalization. I need to do some more thinking about how I came up with the equalization that was implemented.

Hi everyone. My name is James. I'm new on this zone. I would like to ask if you have the diagram of this board and possibly have the value of each resistor and zener diode. Any help will be appreciated. Thank you!

This board came from a power amplifier (a local brand) probably a chinese brand. They called this a stepper and obviously has an issue.

Hi everyone,

Here I present an amp design that was inspired by HITACHI balanced VAS topology.
Open loop response is nice and flat in the audio range at 85dB, dipping to 75dB at 20KHz
THD shows to be around 0.0007% into 1khz.
This is not fully finished design.
I am hoping that with the help of the community this can be polished and I am excited to make actual boards.
I am attaching LTSpice file so feel free to download and tweak as you like.

Input stage consists of
LTP with low degeneration resistors,
constant current source supplying 1mA (not sure if that's enough),
and current mirror utilizing helper transistor.

VAS is balanced and cascoded.

Simple Vbe multiplier.

Simple 2EF output stage.

Idea is to use this amp with 36V power supply.

Things that probably will need further testing are the phase margin, distortions at 20khz, step response.

Thank you for looking everyone.

Hello,

Long story short I suspect tilting back speakers about measly 10 degrees give or take would positively affect imaging.

This is a thread where it would be nice to collect some observations and experiences on tilting back loudspeakers, is it worth it.

Without further ado I'll explain an observation I had recently from VituixCAD simulation and I'd like to know better what you have experienced in terms of sound stage height and / or stability with and without tilt. If you have any comments regarding vertical early reflections and speaker tilt and height, crossovers, how we perceive the vertical reflections, what ever related.

There are attachments after the longish text explanation, scroll back and worth, it was bit hard to condense.

Observation from simulations:
Multiway speaker will have narrowing vertical response around crossover frequency on most typical two(+) way speakers between a tweeter and a woofer due to the drivers being not coincident but stacked one above the other, lobing. With symmetric crossover this narrowing is symmetric to vertical angles relative to listening axis meaning that above and below listening axis the frequency response is roughly similar 10 and -10, 20 and -20 etc.

On a typical listening situation a loudspeaker is positioned so that listening axis is about at ear height which is 90cm from floor in this example. Usually rooms (here in Finland at least) are about 2.5m tall and listening distance is 3m. Due to speaker and listeners ears being closer to floor than to ceiling angles towards first vertical specular reflections differ between floor and ceiling. On this example scenario the angles are roughly 30 degrees towards floor specular reflection and about 50 degrees towards ceiling. This means that with symmetric crossover frequency response towards these reflections are different. Also, floor being closer the path length through the floor is shorter than through the ceiling and this means less attenuation through floor reflection, which is louder of the two and arrives first to ear, right after direct sound making it probably dominant of the two.

Now the hypothesis from this observation regards to "vertical imaging" is that due to differing frequency responses that arrive to ear from high up and down below, and particularly nasty zigzag move right around crossover point which usually is right at the important vocal range and where ear is sensitive, affects perceived vertical image height/soundstage clarity/how would you call it. This is something I think I heard with quick listening test and would like to know what you think and hear.

Tilting speaker back some 10-15 degrees on this example scenario will make the response towards the first reflection points similar, no zig zag move and highs towards ceiling get boost and respectively attenuation towards floor. Same thing happens with my prototype speaker. I assume but don't know if its true, that if there is more sound through floor than through ceiling, and especially since the floor reflection arrives earlier, the perceived sound image height stays low. The zig zag move perhaps makes important vocal range image little bit hazy because there is more sound towards floor in general except around the crossover there is suddenly more sound to ceiling which perhaps pulls up this frequency zone a bit in perceived image, a confusing thing. When the two reflections are roughly balanced I assume sound image is stable at the speaker height, less confusing perceived vertical image. In addition if there was more highs through ceiling and more lows through floor would possibly elongate perceived vertical image some. If you know better or have links to studies, please comment!

This makes a lot of sense to me logically and I think I heard it but not so sure if its just bias 😀 Keep in mind direct sound frequency response also changes as speaker is tilted, but this could be adjusted if the scenario is planned in design phase. I'd be glad if you can share thoughts on it and especially if you have tried it. did vertical image or image in general get somehow sharper and perhaps even taller?

Here are some attachments for the text above.
This is made up sim with ideal drivers, its a two way box with 5" woofer and 1" tweeter, 20cm wide and 31cm tall, rather typical bookshelf speaker. The situation would be about the same for any loudspeaker that has a small tweeter and a woofer who are not coincident but stacked one above the other, perhaps 90% of all speakers out there, could be two or more ways, bookshelf or tower. Speaker with coincident tweeter and woofer (or a fullrange driver, or an array etc.) would have pretty much similar frequency response towards these reflections and perhaps there is not much difference. Perhaps this is partly the reason people like such speakers?

Drivers and baffle, responses made with mic at center for simplicity.


Here is the basic simple simulation setup. Arbitrary crossover point at 2500Hz, could be more or less doesn't matter, this is just some plausible crossover for such system.


Angle calculations, the room setup and simple right angle triangle calculator to get how much I need to increase tweeter Z coordinate with the Tilt angle in simulator. On the calculator B was set to driver c-c distance of 10cm and desired angle to alpha. This is not too accurate do it like so but accurate enough to zone in the tilt for listening experiment.


Here is the angles visible illustrating zig zag. Bottom graph shows -30 angle towards floor, direct sound and +50 angle towards ceiling. The zig zag happens roughly between 2-5kHz in this example, when ceiling reflection is relatively louder than floor reflection ( I think these graphs don't include attenuation due to path length ). Same graphs are also in power and DI window as light blue and light brown, these are default in VituixCAD so one doesn't have to setup the user defined angle if you are checking the stuff out in your project.


Now with small 10 degree tilt we can align the floor and ceiling reflection responses better so that dip due to lobing on both reflections happens roughly at same frequency. The hypothesis was that now both floor and ceiling reflections are about as loud through the whole frequency spectrum keeping the vertical image more stationary, stable. Alignment is not perfect but there is about no zig zag. 15 degrees would work fine as well but in the example listening axis response suffers already quite much. I don't know how bad this would be with your speaker, perhaps affects perceived sound or not.


Here is also 15 and 20 degree tilts. 20 degrees is too much in this case, zig zag is worse.


And here is completely another kind of system a three way with waveguide based on real measurements, not sure what kind of crossover slopes are, symmetric enough at least to make the zig zag. See the ER lines, light blue and brown. The first image is system adjusted before checking out this stuff, for basically power and DI and that kind of stuff. The second image shows that if I was to sacrifice some of the other lines and just adjust delay of the system to get tweeter back some and steer the nulls toward reflection angles the zig zag is gone. Not much of a sacrifice because the response can be adjusted for this new delay. Third image also tilts the waveguide little, now there is relatively more sound through ceiling on high frequencies than through floor, similar thing than perhaps a thick rug does as well. As frequency goes up more from above and less sound below listening axis. Here the 10 degree tilt works just fine.



I suspect your speakers and listening setup are suitable for the test. If you try tilting your speakers I suggest you to concentrate on vocals when listening for the effects of tilting but anything goes. What do you hear or is there any difference at all on sound image?

Here are some quick rough numbers to tilt your speaker roughly 10 degrees, put some Lego (a standard block is ~1cm high) or something else under front edge of your speaker. You could try more or less tilt if you wish. Careful not to tip over your speakers, I don't want to be held responsible for broken stuff! 🙂 If you have DSP you could just delay the tweeter (driver closest to ceiling) some extra to tilt the nulls instead of physically tilting the speaker.

Box depth affects how high the front edge needs to be lifted to achieve 10 degree tilt. Here is few for starters:
20cm deep speaker box use ~5cm riser on the front, 5 lego blocks.
30cm deep speaker box use ~7cm riser.
40cm deep speaker box use ~10cm riser.
50cm deep speaker box use ~13cm riser.

ps. I'm sorry we have people coming in for visit so I might not be able to comment extensively too much until weekend. I hope the text is extensive enough to get an idea and comments flowing 🙂