Good evening.
I planned on getting out of this hobby, mostly due to lack of time for building and learning.

So, I thought "why not make a pre amp and a simple power amp and leave it at that?".

I decade or two ago I build Greg Balls GB150 and for some reason I sold it.

I managed to find old kits for 4x channels and thought that this will take no time at all.

The PSU is ok but fuses are blowing when I connect the power amp PCBs.

I thought that there must be a short somewhere and measured resistance between the positive and negative rail on the PCBs (PSU disconnected) and found it to be just above 1R.

So, does anyone remember these old amps?

I have attached the schematic which should be mostly correct anyway.

Hopefully someone can assist me with some troubleshooting, I kind of realized that I should do something I actually can learn instead but I want to finish this 🙂

Hi, What are these 2 components connected to the Cathode / Ground of the 12AT7 tube. Also, what would be their purpose/function? This tube is the 2nd tube in the phono stage. 12AT7 --> 12AT7 --> line stage

Thanks

Interlude Audio launched earlier this year with the release of an Analog HAT and we’re now ready to launch our Digital HAT.

We’re compatible with RPi 3, 4, and 5 and support auto config, which means there’s no tweaking the config.txt file. Our drivers are integrated with the Raspberry Pi OS, we have support for Volumio, and we’ve built our own Busker OS based on the Raspberry Pi OS, which includes support for Spotify, Airplay, and Roon.

Analog HAT
The Interlude Audio Analog HAT offers a high quality power circuit which ensures exceptional DAC/ADC performance. This sophisticated design includes a meticulously crafted power tree, providing clean, stable power to all parts of the circuit, and effectively isolates noise. We include a 12V power supply which powers both the HAT and the RPi.

Utilizing the CS4272 featuring wide dynamic range, negligible distortion, and low noise, our Analog HAT achieves an SNR of 105.7dB, dynamic range of 103.9dB, and SINAD measured at 94.9dB.


Digital HAT
Based on the WM8805, to reduce jitter and maintain signal integrity, the Interlude Audio Digital HAT provides both coax and optical input and output. Furthermore, our dual oscillator design guarantees zero jitter across all sample rates.

The Digital HAT stands out in its ability to handle a wide range of sample rates, making it a versatile choice for high-resolution audio playback. We’ve made monitoring the sample rate of your audio simple by including LEDs which indicate the current sample rate in kHz: 44.1, 88.2, 176.4, 48, 96, and 192.



Please visit our website for more information: interludeaudio.com

Well, I am putting Greg Balls GB150 together and for some reason thought it a good idea to try one of those Chinese smps.

I got one 300W with +48 0 -48 secondaries and the regular L-PE-N primary.

I added a 2A slow blow and it keeps blowing at startup. Even with the amplifier disconnected.

Am I missing something?

Just completed V2 of the fully active, zero/open baffle units.
Login to view embedded media

which driver sounds the best.. I want dry..
https://www.eighteensound.it/media/W1siZiIsIjIwMjMvMDcvMTcvMTRfMDVfNTlfMzA3XzE4U3ViX3YxXzEucGRmIl1d

it should work well with this..
https://www.eighteensound.it/media/...dfNzcxXzE4X1NvdW5kXzEyXzJfV2F5c192MS5wZGYiXV0

I'm thinking of building passive crossovers for tops and subs..

/anders

Hi ! i am testing caps i have at hand with this meter


some caps rated 22mF measure around 17mF
i wonder if i can still use them without issues
Other NOS caps instead measure accordingly with their rating
Moreover i would like to understand if there is a cheap but reliable way to check the ESR
I have seen only a very expensive meter
Thank you all sincerely

I bought a defective DALI SWA 15 subwoofer and the builtin Class D amplifier is not amplifying (can hear very low signal), i had contact with hifiklubben (the reseller in Sweden) so they could contact dali but they dont give out the servicemanuals to endcustomers.
Is there anyone here that can manage to get a hold of one or mabye point in a possible direction that what could be wrong ?

The fuses was blown (all 3) so the mosfets and 2 controller ic's is now replaced by a very experienced repairman.
But now he has come out of ideas. Apparently the transformer has a big load and he cant get it to be normal.

I have built a movieroom on the second floor of my garage and are experimenting on how to get a versatile soundsetup.

Reciever : Nad 758v3
Amplifiers : 1 Crown XLS 2502, 2 Crown XLS 1002 and one CewinVega 2.6kW
Front speakers : 2 homebuilt ported boxes with Audes 1" tweeter and a Audes 8" woofer in moviemode and 2 CerwinVega Clsc215 for partymode
Center : 1 homebuilt ported boxes with Audes 1" tweeter and a Audes 8" woofer
Sidepeakers : 2 homebuilt ported boxes with Audes 1" tweeter and a Audes 8" woofer
Rearspeakers : 2 homebuilt ported boxes with Audes 1" tweeter and a Audes 8" woofer
Front cornersubs : 2 homebuilt ported boxes recessed in the walls with Dayton Ultimax UM18 tuned to 20Hz
Rear cornersubs : 2 homebuilt ported boxes recessed in the walls with PA 18" tuned to 30Hz
Subcontroller : MiniDSP 2x4HD and Umic1
Visual : Philips The one 75" screen
Speakermeasurements : Dayton Dats v3

Fostex FE206NV project is finished.
Some ML-TL derived from a Martin King project for Lowther that with some modifications fit into the TS parameters of the Fostex, these being very similar to those of the Lowther Dx2.
http://www.quarter-wave.com/Project04/Project04.html

To equalize this extended range I decided on two notch filters centered at 2.6k and 9k and a step speaker that starts at 150 hrz.
It has a rise of about 5 dB above 10k, very suitable for those of us who have lost sensitivity in those highs.
The impedance was very friendly for the tube amplifier with which this system will be used.

Note: Hornresp was used for the design and simulation of the box. Jeff Bagby's spreadsheet and XSim were used to design and simulate the filters. For response measurements the REW and for impedance the LIMP. All software free to use. It was measured with a Dayton IMM6 calibrated microphone.
Sorry for my english

Hi,

I have made PCB layout in Eagle 6.5 for DOGC-H amplifier designed by Dr. Borivoje Jagodic.

PCB is not tested yet, so any improvement suggestions are welcomed.

Hi ! sorry if the question sounds confused
I still think that a low THD is a good think to get
I was reading a review online and i found these graphs
https://www.audiosciencereview.com/...ds/revel-m106-bookshelf-speaker-review.14363/
considering the graph on the right i have the feeling that using this speaker full range could be a very bad idea
Anyway i wonder if i had to use a high pass filter on this speaker what would be the best crossover point
I mean how much THD can be tolerated ?
What is missing is a IMD graph
I am sure that exciting this speaker with powerful 100Hz signals would be devastating for the overall performance

https://www.diyaudio.com/forums/attachments/solid-state/1001999d1638447744-cfh7-amp-cfh11_1v2_sch-pdfFollowing the naming convention for amps used in this thread and also first posted here, I am starting a new thread as this is not anything like an Apex design offshoot anymore:

100W Ultimate Fidelity Amplifier - Page 820 - diyAudio

However, I think I will keep the standard naming convention that Apex Audio likes to use. So CFH7 stands for Current feedback HexFET with 7 active components. The amp arose out of the surprisingly successful FH9 and FH11/12 amp designs from the same thread, but with a current feedback topology that I believe was first used by Gaborbela as described here:

My first DIY amplifier 20 years a go - diyAudio



This same topology is also used in the very popular VSSA series of amps (VSSA, PeeCeeBee, FET-hex explendit, etc). My biggest inspiration for using the Gaborbela topology came after I built the amp described here:

VSSA Through-Hole Version by Jason - Page 86 - diyAudio

Now, I have applied the Gaborbela topology with the great sounding, popular and cost-effective IRFP240/9240 hexFETs, while reducing the number of active component parts count from the FH9, which has 9, to 7 transistors by elimination of two transistor CCS's. The simulations of this amp in TINA indicate a surprisingly good level of performance. The usual BD139 is still used for temperature compensation as a Vbe multiplier. Very large 4700uF rail caps are needed if you want the squarest square waves, but smaller 1000uF caps would probably sound just fine.

Here is the schematic:



And here are the simulated results:

1kHz sine wave at 50v p-p with 80mA quiescent bias current:


50kHz square wave:


200kHz square wave:


FFT spectrum at 1kHz:


HD components at 1kHz sine wave excitation:


HD components at 20kHz sine wave excitation:


Gain and Phase as a function of frequency:


As you can see, the predicted HD of 0.00084% at 1kHz and the clean, sharp-edged square waves are very good indeed for a 7 active element amp that uses nothing exotic or special. Vishay hexFETs are available for under $1/ea, so this amp is literally under $5 to build. The bang for the buck on this amp is pretty much up there.

So, it's still in simulated schematic stage at this point and un-tested. I would welcome someone taking a crack at the layout for a Sprint/Gerber file and we can then test and listen.

Edit Aug 3, 2016: several members have pointed out that this topology probably originated from Japan in the 1970's:







Version 1.1 schematic that Idefix will design layout for:


Update Aug. 7, 2016: Idefixes generated the new layout (with associated schematic for parts numbering):



We are going to press with this layout - a masterpiece - great work Idefixes!


BOM for above amp:

http://www.diyaudio.com/forums/attachments/solid-state/572548d1475477936-cfh7-amp-cfh7-bom.txt

Edit: Aug 15, 2016 - Sonal Kunal has just developed a single sided layout - still not final but very cool looking.



Edit: Aug. 16, 2106 - Latest layout from Sonal with no onboard inductor but 100mm max size


Edit: Aug. 17, 2016 - Idefixes has a beautiful new 2-layer layout that re-routes the ground bus to reduce RF spray onto the input stage:


So many layouts to try!

Still4given or Andrewlebon will probably be the first to reach first sound.

Andrewlebon in progress...


Still4given in progress...


I can't wait to see someone with a small waisted F1 car style board as Sonal has prescribed.

Edit Aug 19, 2016: Still4given had built and verified that Sonal's layout works but requires fixing wiring of Vbe multiplier as that has an error and also 4.7R gate stoppers are not enough to prevent oscillation. 100R seems to work there.

CFH7 Amp - Page 21 - diyAudio



Here is a dual output pair version called CFH9:


CFH9 works well - nice square wave:


CFH9 in stereo with Juma's Easy Peasy cap multiplier:


This is one of my top 3 amps.


Dec 16, 2016: Thanks to Thimios for finding grounding issue in design. Here is final mod to achieve very good PSRR and low THD. See post here

http://www.diyaudio.com/forums/solid-state/294834-cfh7-amp-82.html#post4920073



Edit Dec 5, 2021: saddevil has made a nice layout with some improvements in a cap Mx for the front end and one for the main outputs. This should have a really low noise background.


More info and Gerbers, here. Schematics here.

I have seen where someone has added a 12v relay for switching to the mc103, but I would like to put a module in that automatically switches to the active source. I know my Fosi v3 monoblocks have that feature built in and I think it would be nice to integrate jnto mine.

What do they call a board that does this, and what do I need to look for in one when I find one?

Did anyone else stupidly not properly save their months and months worth of adding items to their basket, only to lose it all when the Mouser site had some issues last week.!
Bugger.
Lesson learned!

Hello,

All This is Raghu from Hyderabad INDIA iam interested in discussion of Audio and Video.

Thanks
Raghu

Hi
I have technics sl-pg200a, bought it just to take cdm4/19 out of it. Also bought used Philips monokit board based on saa7310 and zc99696p which I thought should be better than mn6626 (which is used in technics). But after testing the Philips board with the mechanism I noticed that seeking between tracks is much slower than in technics and also a bit noisier. Is that normal behaviour or should I look for some issues on that board?

So I’m looking for a tweeter to replace my initial design for a large high power 3-way studio monitor main.
The bass is a 12” Fane pro driver.
The midrange is also a Fane; 5” studio.
Initially I planned to use a Fane 1” compression driver in a small waveguide but
A) I’m unable to source the Fane CDs anywhere but in UK which would amplify the cost dramatically, and
B) I cannot find a waveguide small enough and still rugged enough to fit the baffle and carry the weight of a solid CD.
My backup option is to use a leftover Eminence APT50 but I don’t like the plastic horn, I’d prefer something aluminum and I’m unsure about its performance.
Also it is a tad to big.
So I’m considering a plan C then; a traditional tweeter of small footprint.
But I have some requirements:

• no bigger than 7cm diameter, preferably a neo magnet
• metal grill for protection
• slightly hornloaded is preferred to control the directivity and boost the sensitivity
• high power high sensitivity from 3kHz
• proven vendor, spare parts/replaceability
• sweet sound but details are more important / honest revealing
• no plastic chassis
• easy mounting cutout
• cheap

Any ideas?

Sold

Hi

I hope someone can help me in my search for a very specific part - or maybe advise an alternative way to achieve the same with other means.
So, in short I am looking for a potentiometer with a center detent - but would like to have one that is spring loaded in both directions.
Meaning that if I turn to one side and release it I want it to snap back to the center detent. Naturally the same for the other side as well.
I have searched a lot but have not been able to find anything except spring loaded switches. But that is not what I am searching for.
Thinking old motorized tuners would use something like that.
Alternatively, if there is an easy way to create/attach a spring load mechanism - but remember working both directions then that would potentially
be even better if I that way was also able to adjust how strong the springs could be.
Hope someone has a great idea.

Thanks

https://audioxpress.com/news/ess-te...igh-performance-8-channel-ess-sabre-smart-dac



dave

I was offered a Sae A205 amp, there is not much info out there, plenty of power, looks like a Acurus or Adcom mosfet amp.
but I am not sure.

Is this a Mosfet amp ?
what are the bias number without a service manual ?
Is the design any good ?

100wpc Class A/200wpc Class AB1.
4x Toshiba 2SA1302, 4 x 2SC3281 each side

thanks for your help

Is there someone who can explain this further and even have experience:

https://lyngdorf.steinwaylyngdorf.com/lyngdorf-ls-1000/

I can see that the tweeter is slightly angeled. But Lyngdorf say this:

The Lyngdorf LS-1000 Left has a sound dispersion slightly beaming inwards when placed on the left side, away from the side wall and towards the listening area.

The Lyngdorf LS-1000 Right has a sound dispersion slightly beaming inwards when placed on the right side, away from the side wall and towards the listening area.


I have been explained that f ex JBL 4435 have this feature for high placement in studios.

I ask because i am interested to make a similar inwall line source whitout physical toe-in

Am originally power supply designer. Good for resolving power supply issue for amp.

New member here, this is my introductory post.

I started my audio journey restoring valve radios, moving onwards to building valve amplifiers and the occasional solid state build.

I enjoy the building as much as I do the listening.

Looking forward to contributing and learning from this community

Gabriel

Got an old Denon CD player which I terminated but not before doing some tests. Besides SM5840 and 2 x PCM61 it had the often found dual tracking regulator M5290P. It came to my eye that this regulator is pretty silent.

Never thought about that. This is a regulator of at least 25 years ago. Check that datasheet!

Hello,

I have an amplifier Marantz-95 equivalent to Philips DFA 1000 which needs to be serviced.
For doinfg so I need the corresponding service manual.
Any input to get it will be welcomed.

Thanks a lot


Alain

Marantz PM-95 Specifications Marantz

Hello,
During my internet travels I bumped into this guy. I wonder if anyone here is familiar?

https://kaamostech.com/

Guitar players spend years to find the right mix of 2 or even 4 speakers in their cab.... Like a cook blending spices.

I was looking at compression drivers and suddenly thought "what about mixing 2 or even 4 different ones on one horn (with a manifold). Obviously ones with similar sensitivity and impedance....

My rationale is: Every driver has different artifacts, resonances, diffracions and breakup modes.

A single driver that has a +2 db spike somewhere along the frequency plot would only show up as a 0.5db hump in the combined output of 4 different drivers. Also it would be interesting how a titanium and phenolic driver sound together on a single horn.

Is this a silly idea?
Has it been done before?
Are there any obvious negatives?

I am interested to hear what others think of this.

Im trying to build the eval board of si8244 which is basically a half bridge design. I want to drive subwoofers with it. Is there any issue with bus pumping which is usually observed in Half bridge design?
Did anyone listened to the si8244 eval board? how is bus pumping with it? these days some diy members say that bus pumping was old generation issue but with new gen its not a problem.

A friend has loaned me his 521 complete system for a couple of months. System includes 2 Emotiva amps ,analog crossovers and speakers and all connectors/cables. Only issue is I have is no sound )-: . Crossovers have both red and green LED's lit -is this normal? Have tried two different pre-amps -so some sort of weird pre-amp failure is ruled out ? Secret handshake ? Hidden mute function ? Moon phase ?

I attach schematic for traditional hybrid amp that runs +-17vdc and has a series electro cap and resistor as a simple way to protect phones from electronic failure ... according to D. Self. I don't understand how this polarized cap survives polarity swings.

I tinkered with parallel opamps, as seen in the O2 amp, which worked great even with 62 ohm AKGs. Now I want to try hybrid discrete circuits but I am wary of mistakes.

2. Can feedback be taken from the load side of this circuit.

Hallo. Im jack from indonesia

I disassembled the vintage two-way bookshelf speakers: Denon SC-C3. I was a bit surprised with their crossover networks. They have only high-pass filter on the tweeter comprising a 3.3uF and a 0.47mH combo forming a second-order filter. And they have no low-pass filter for the woofer. The sticker on the cabinet is labeled crossover point at 4kHz which is consistent with high-pass’s component values.

Although I was surprised, I could remember that there’s a case in which the designer may intend to utilize the “natural roll-off“ of the woofer. However, by doing this, there are few disadvantages which are the dispersion, woofer’s break-up/beaming and off-axis radiation problems. So, does it mean these issues could actually be ignored?

If so, what would be the tricks for using this method? I mean how to choose the proper crossover frequency for the high-pass filter of the tweeter with the presence of woofer’s off-axis response variety i.e. 15, 30, 45, 60 degrees? Because, in typical configuration, the woofer would be employed low-pass filter below the frequency where off-axis variation curves occur.

This project is considered an upgrade to DAC1136, as the chip for DAC1136 is difficult to obtain. However, DAC1146 is relatively easy to purchase. I purchased 2 and they are very new. There are two versions of DAC1146. The first version has a plastic shell that is all black with silk screened white font. The internal R-2R part of this structure uses an AD7541 ceramic encapsulated gold cover plate. The second version is a plastic shell with white stickers, which uses ceramic packaging for the AD7541. Regardless of the structure, it can refresh you and his voice is very good. It is not something that IC can imitate. I like modules.Now share with everyone.You will get his PCB at a very low price. But he is in China.If you are a friend of the European Union. Please provide the IOSS number, which consists of IM and 10 digits. The mailing time is about 10 days. All PCBs consist of four parts: audio input board, format conversion board, DAC decoding board, and power board. You can play app content through a Bluetooth chip (purchased in China, manufactured in Shenzhen), or use CS8412 coaxial to play CD content. COMBO384 can also be used to connect to a computer for playback, and there is also an external input IIS interface for connecting to Philips turntable playback. I will provide Taobao product connections. You can use Taobao's overseas warehouse to purchase. If you need assembly instructions and BOM list, please send an email: 410746700@qq.com，My store address: hikvocal.taobao.com

Many people in China like PCM63P and consider it an irreplaceable project compared to PCM1702. Because PCM63P has a more delicate sound, and PCM1702's digital defects cannot compete with PCM63. So I created all the projects related to PCM63.Now share with everyone.You will get his PCB at a very low price. But he is in China.If you are a friend of the European Union. Please provide the IOSS number, which consists of IM and 10 digits. The mailing time is about 10 days. All PCBs consist of four parts: audio input board, format conversion board, DAC decoding board, and power board. You can play app content through a Bluetooth chip (purchased in China, manufactured in Shenzhen), or use CS8412 coaxial to play CD content. COMBO384 can also be used to connect to a computer for playback, and there is also an external input IIS interface for connecting to Philips turntable playback. I will provide Taobao product connections. You can use Taobao's overseas warehouse to purchase. If you need assembly instructions and BOM list, please send an email: 410746700@qq.com，My store address: hikvocal.taobao.com

Six chips can work in the same environment, which is the best way to choose the one that suits your listening experience. I also created two methods. Operational amplifier and TUBE output. Just select the digits through format conversion.Now share with everyone.You will get his PCB at a very low price. But he is in China.If you are a friend of the European Union. Please provide the IOSS number, which consists of IM and 10 digits. The mailing time is about 10 days. All PCBs consist of four parts: audio input board, format conversion board, DAC decoding board, and power board. You can play app content through a Bluetooth chip (purchased in China, manufactured in Shenzhen), or use CS8412 coaxial to play CD content. COMBO384 can also be used to connect to a computer for playback, and there is also an external input IIS interface for connecting to Philips turntable playback. I will provide Taobao product connections. You can use Taobao's overseas warehouse to purchase. If you need assembly instructions and BOM list, please send an email: 410746700@qq.com，My store address: hikvocal.taobao.com

Hi
I am Xaver an a Elektronics Enegneer.
I have already built my first preamplifier. With an integrated phono stage. The amplifier has a 5751 input tube in the phono amp and after that a e82cc. The line-amp after that is a parallel 6072a like the Kondo amps.

I also built a magnetic tone arm according to the Schröder principle on a Garrard 401 player.

My new project will be a horn loudspeaker with a JBL 2451 with aluminum cone in the midrange. The horn should be conical like Bill Woods.
Underneath, the bass horn is to be driven by a JBL 2227. The horn should also be conical.

Like to be with u

Hi 😀. I'm interested in modifying my existing receiver and I'm here for any and all advice.

If you would like to understand the title, please Google "the infinite monkey theorem"

This will be the start of my build log. A little background on this: For the past year I have been pouring through everything from white papers to text books, and sending out emails all over the place to learn about audio and speaker design. I've gone down so many rabbit holes. There is so much to learn and so many details you can expand upon in design. There's also something called the law of diminishing returns. At this point, I just wanna make something. So here we go:

T he objective is a set of active monitors with the best distortion figures possible while still being somewhat compact (and before you say it i am WELL aware of how many other designs there are out there). Some components will be expensive, others will not. Trying to be at least somewhat cost effective... I'm not the monopoly guy.

Here's the concept:



(I apologize for the chicken scratch, but I'm currently on vacation and decided to sketch it out a little with a notepad on hand)
Starting with the body: I found a little while ago a company that makes prefabricated carbon fiber parts. In this instance, a carbon fiber tube ( https://dragonplate.com/1075-id-x-48-carbon-fiber-tube ). Split that in half, and possibly a little more, and you have yourself a very rigid skin. It will be attached to a base (most likely MDF) and have a small bracket in the center (more on that later). Next would come a CLD layer, then the rest of the contents of the speaker.

The inside will be in 4 pieces. Each will contain a driver except for the one with the electronics. The 2 pieces on the sides will each contain a seas 8" sub. The placement will allow for force cancelation of each woofer allowing it to hit lower frequencies as well as cancel out any modes not supposed to be there. Additionally, because sound becomes omnidirectional at lower frequencies, and because it's a round enclosure, I shouldn't have to worry too much about distorting modes caused by edges and baffle stepping.

At the front will be an MTM configuration for the rest of the frequencies. This will be a small enclosure that has its own sound dampening seperately from the main chamber. Originally I was thinking about bliesma M74 mids, bit it seems purifi still wins this round with lower distortion figures. Will be going with a set of 4" woofers. The trade off there is efficiency. The tweeter will be a RAAL 70-20.

The last piece will be the electronics enclosure. Going with a hypex fusion amp for this one. I would have loved to design the electronics as well, but I do not have access to a lab at the moment to test them so this is the next best thing lol. From there it's just a little more sound dampening, a cap on top, and voila.

With all that said, I still need to sift through all the particulars. Am definitely going to need to dust off my CAD skills to make sure everything fits together the way I think it will. May fiddle with the design a little more, but all in all, I think it'll turn out great! Would love to hear from those a little longer in the tooth who have more experience in this than I. This whole thing has been a learning experience, and we aren't done yet.

Hi everyone,

The last few months have brought me some strange experiences in my sourcing of 45 tubes for my DIY amp. I had one seller who refused to provide precise measurements of his tubes, even though he listed them as testing "good". Which to me means nothing. Another one listed measurements and also gave me more details by email, but he backed out once I had purchased the tubes, perhaps because I mentioned that I was going to test them on my Pentavac tube tester.

However, the case that intrigues me the most is an experienced seller with whom I have been doing business for over 5 years. He has been selling tubes for nearly 30 years. He claims that the 45 is an extremely difficult tube to test and that he tests each one on four different calibrated tube tester.

When I ask him for more explanation on these testing difficulties, he vaguely mentions a temperature to obtain at the level of heating the filaments, as well as a "hard" material of it, without really giving more details.

Is the 45 really so difficult to test? I would like to have opinions on the question.

For my part, my Pentavac is equipped with an external power supply in 2.5 or 5V to test among others 45, 2A3, 300B. I have tested several 45 with it and I am always happy with its use. I have several that have tested with excellent emission between 95% and 105% of new for example, but also several that I had to reject. In two recent cases, I have returned them to the seller because they did not match the NOS measurements announced.

Finally, recent experiences have shown me a strong intolerance of some sellers who do not accept that we buy tubes from them if we test them afterwards. De facto, they reject the calibration of our tube tester and do not want to know anything about trading with customers who would be likely to test their tubes later with their own tube tester.

Personally, in this kind of business, it seems to me that we must at best have a common reference. The seller must be able to ensure the quality of the tubes he sells and the serious buyer, to be able to check everything after purchase.

Sébastien

F4 boards
Four were used for balanced headphone amp
Two for standard F4
$125 shipped to CONUS

Sorry for the clickbait title as this is not really about ESS hump. Or is it?

As I was testing my ES9822PRO board I noticed that the 1kHz FFT spectrum has high harmonics up to 100kHz and beyond.

Here is ES9038Q2M to ES9822PRO.



The harmonics of 1kHz continue throughout the spectrum albeit at a low level.

So are these harmonics coming from the DAC or the ADC?

Here is the same ES9038Q2M DAC but with AK5394 as ADC (fs is now 96kHz).



So it seems DAC is the culprit. Or is it?

To verify I switched to a 1kHz oscillator (my take on Victor's). Here is 1kHz oscillator + AK5394.



As expected spectrum is quite clean.

Let's repeat that measurement with ES9822PRO.



Surprise, surprise. The 1kHz harmonics are back. Also ES9822PRO has high harmonics.

So it appears that ESS architecture (Hyperstream?) causes high harmonics both in DACs and ADCs. Is this the cause for the infamous ESS sound?

I have been studying a lot of driver measurements from different sites, and what I can tell is: cheap drivers measures poor, midrange driver can measure excellent or poor, hi0end drivers usually measures great, but can bad too.
My main interest were midrange drivers 3-5 inches, both cone and dome. As a result I saw that:
- Scan-Speak 12MU, one of arguably best midrange on this planet, measures just OK
- SB Acoustics NBAC15 - kills the 12MU in terms of harmonic distortions, especially third, costs 20% of the former
- Accuton - despite the cost - very high distortion on 3rd harmonic (few drivers checked, 90-170mm)

Yet, most people find their sound qualist in following order: Accuton, SS, SB Acoustics. So, what else really matters to determine if one is good or great great driver? Waterfall? Time-Energy Curve? On-Axis response?
Why to pay 10 times more for Accuton, if cheap SB has literally every harmonic order better?

And, if those are telling us next to thing, why to measure it at all (besides frequency response)? Highly respected Seas drivers are nothing special in terms of harmonic distortions, yet a lot of hi-end manufacturers are using them.

I was looking for a drivers to handle something between 400-3000Hz, and while already looking on a quality manufactured drivers, why should I actually spend hefty money on Scan-Speak or Accuton? Actually why to buy Illuminator 12MU, if the old SB12NRXC measures actually the same on distortion graphs? And where I can clearly read/see the advantages of Scan-Speak over the paper SB?

Yes I know there are big variances in motor design, coil size and so on, which translates to sound, but this should be clearly visible on mesurements.

Or, we don't know what to measure, and how to combine different graphs to get proper conclusion?

If there is no measurable variance, why to pay much more for better drivers? Everyone hears, but noone can measure?

Dear Sirs,
i am a complete newbie related speaker design. Picture of my crossover is bellow - "current" part of the picture.
I am running an open baffle design with middle driver full range (type not known for now), tweeter is P Audio BM-D440S and woofer is SB Audience Bianco-12OB150. Sound is nice but i kind of would like to have more bass - not to much, just a little bit more (bass drivers are still preety new - maybe they need to work a little bit more to get to the level, i don't know)...
Right now the woofer board alone is not to big (can't go bigger because of the living room i have) so i was thinking to put maybe two 12OB150 drivers per side to enhance the surface area.
The problem is those drivers are 8 ohm... putting them in series is not an option so, if i put them in paralel i will have 4 ohm at the end... together with my 8ohm middle and a little bit more on the tweeter, i am worried if the overall impedance will be to low ... (my amplifier is class A F5 clone from Nelson Pass)..... so i am considering putting Rx resistors in series.... those Rx resistors from the "future consideration" part on the picture will have to be big (power related)?! what to choose to put there to get a good sound... type?
any thoughts for this case??
thank you

I purchased some construction plans on Nov. 8th. I expected an e-mail with instructions on how to download the plans within 48 hours per the website. I didn't see anything after checking my e-mail including the junk folder. On Nov. 13th I sent them an e-mail at info@heissmann-acoustics.de with the Paypal transaction information. Still no response. So I'm wondering what's going on at Heissmann. Heismann did have an account here, but I think it's been deleted. The last activity was in 2021 and I get an error if I try to PM the account.

Thanks.

I only know speakers as far as DIY competence goes so this can't be my project, but curious if the concept would make financial sense, and also if anyone else thinks it sounds good.

• It's a stand-alone board/box with up-to-date digital input options, input of which is converted/mixed to a digital 2-channel stereo bitrate and depth suitable for DSP.
• That digital stereo signal goes to a miniDSP type of EQ+xover with 3x2+1 output channels.
• Those 7 output channels are sent to an HDMI output that will be accepted by an outdated 7.1 AVR. Now we have everything to run 3-way DSP speakers and a DSP subwoofer channel, right?

Reason I was thinking of this is that mid-to-high-end AVRs (consumer and pro) can be found cheap-to-free all over these days. Could a device like this be cheap enough to be worth buying for the approx. 100% discount on 7-8 channels of amp?

I want to check the value of the coupling capacitor needed for this schematic, with a 6SN7 with a plate resistor of 47K. The potentiometer in the image is actually a grid leak resistor of 220K.

I found this tool online: https://www.ampbooks.com/mobile/amplifier-calculators/coupling-capacitor/

I’m not sure what to use for “output impedance”, as the tube itself will be something like 7K.

Hi ! I want to build 3 ways pro loudspeaker
My problem is to find a pro subwoofer to made a close to flat 20-100hz at a cheap price any Idea ?

The easy solution is to building a 2 ways loudspeaker with active subwoofer but It's not my goal

My Low mid have 99db
And my horn have 99db (w/resistor)

Thanks in advance 🙂

nicK

I generally really like the sound of my speakers but if I’m ultra critical I may be able to hear some coloration. This is really only audible to me on some spoken word on BBC on line radio where voices can sound a fraction like they’re in a tunnel. I am probably over stating this and it is also broadcast quality dependent of course. Its really difficult to pin point but for all their faults my previous Stirling LS3/6 BBC Ref didn’t seem to exhibit this to the quite the same extent. At least as far as I can remember.

My current 752 Freedom has one rear port and 3 front ones.

How would you go about trying to find out whether this is simply a result of the driver construction/xover or internal reflections through either the ports or the mid/bass unit itself?

If additional internal damping coild be the solution where would it most likely make sense and what material would be best?

Thank you

https://i.postimg.cc/YS9H51Mk/20230503_211023.jpg

https://i.postimg.cc/Qdb9gWdf/20230501_112519.jpg

Hi, I'm Nathan ( from France 😉)
I'm passionate about electroacoustics and loudspeaker design., and I've been following the forum for quite some time, but always submarine!
Now I want to get involved in community projects !

Hi, i want forum recommendation for complimentary to3 pairs for 100w high fidelity amplifier.

I got those caps more than 2 decades ago and used them only for measurement compairments when sorting out 1% caps with my less precision capacitance meter.
Electronic Associates Inc. hermetically sealed capacitors.

6pcs 1uF, 0.05%, 25Vdc, 39.4x25.6x25.6mm (2x0.5uF precision matched by AE)
8pcs 1uF, 0.05%, 25Vdc, 44.5x25.4x15.9mm
8pcs 9uF, 0.05%, 25Vdc, 76.5x54.4x27.2mm
13pcs 2nF and 14pcs 18nF, 0.1%, 25Vdc, 14.4mm diam, 54.4mm long

Please let me know if you are interested in any of those, you pay only for shipping and pay for the caps whatever you find proper, i will donate that sum
to DIYaudio

Still up for sale

I am an amateur brewer, I do music engineering, I listen to music and I make amplifiers. I just joined you and I am here to learn your knowledge. Because I have a plan to make an amplifier. I found a schematic attached to a post and decided to make it and of course I have no knowledge. I would be happy for your help and please excuse my English. What do you suggest instead of 2sj74, I could not find it in my country and did you combine this JFET to N channel instead of P channel? I did not understand the R112 resistor? The outputs are N MOSFET, why is the input P JFET? Can't we make them all N channel? Also, I did not fully understand is this 24 0 24 source or 0 24? Thanks in advance.

Thinking about getting a higher current supply for testing amplifiers under load. Car amplifiers that is, 😉.

I have a prism sound dscope and am able to do power sweeps etc, been doing it for quite awhile.

I'm constructing 4 banks of a bit over 1000W capable 4ohm loads that are fan cooled. I'll be able to parallel the banks up later. They are 45ea of the vishay 2.2 ohm 25 watt resistors. 9 series/5 parallel fwiw. Should be pretty nice.

I currently have a tekpower 15v 60A (and 5A 30v tekpower for debug). Kind of limited for the higher power amps I'm repairing, especially if I want to test below four ohms.

Spark Usina makes an interesting offering out of Brazil. Will do 220A at 15v. Decent price.

I know everyone will suggest this and I've built server power supplies and have one. I haven't figured out how to bypass the overvoltage. So it's only good to 13.8v which isn't ideal. Pretty common to hit the overvoltage barrier with sever supplies I believe.. I used this one before I got the high power tekpower.

I have access to 220v 20A at my workbench fwiw.

Wondering if I'm missing another option? Would like to be able to do 200A at 15v at least. Needs to monitor and display both current and voltage too.

--------
Ended up buying x3 of HP dps-1200fb hstns-pd19 and modifying... This thread became kind of a how-to.. 🙂

Hi Guys,
I'm Zak from UK...just joined the group. Just dropped by to introduce myself. DIY is my hobby, so looking forward to getting some great advice from you experts.

Cheers

Hello everyone!

My name is Adrian and I am from Romania.
As many of you around here, my passion for audio is pretty high.
I hope I can learn alot from you and also you from me! 🙃

Greetings!

Together with a good friend of mine I am planning to build a class A amplifier.
This amplifier we are trying to build it supposed to be something special.
In this regard we did our best in order to achieve our goal.
So,...we started to design our own PCB's and first of them is a DC regulator based on LM338T and a CRC filter.
I will upload here a image with it just to know your thoughts.

The DC regulator it will be placed on the same heatsink as the amplifier board. So don't be distracted by their own small heatsinks.

Enjoy !

Up for sale 16 devices in total. P/N matched. Part of Zhou Fang's original run matched @ 500mA. These are unopened / unused. Stickers show 1.969 to 1.976 across all devices P and N. Can't be many left like this. $350 USD. Shipping at buyers cost from Melbourne Australia. PM if interested. Thks!

I'm in need of a pair of GRS PT2522-4 for a current project I'm pursuing. They don't need to be cosmetically perfect but functionally perfect is a must. The tweeters must also be located in Canada for ease of shipping and tracking abilities. If you have a pair in excellent but not necessarily cosmetically perfect condition that you'd like to unload, please message me with your expectations. As these are for testing/experimental purposes, I, like anyone in Canada currently, would like to keep things as affordable as possible within the confines of fairness to the seller and I.

Got some, lemme know.

Shane

Hello my name is Mitja I'm 32 and my Hobby is Chiptuning. I own few geniue tools for working with ECU's Magicmotorsport Flex, Alientech Kess3. I joined the Form because of post how to make volt mode to server supply and I want to make it like battery stabilisator for car while programing ECU.

22v @ 60A filament.

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As the title says…..what would/could you build with $1K? Doesn‘t include cabinet materials

I'm in planning process of a 4 channel Amp for active speakers. The idea are to use a

• miniDsp Flex Eight
• a 4 channel Aleph for driving mid (Monacor SPH-165KEP, 89db in a closed 10l box) and tweeters Monacor DT-25, 95dB).
• a 2 channel Class-D 100W for 2x 10" subwoffers. (another project, just for information)

Powersupply: I'm considering
2x Nelsson bipolar power supply, with 1x 600VA transormator (or 2x300)
4x Nelsson bipolar power supply, with 2x 300VA transormator (or 4x150)
It will depend on space in the chassi when everything else are in place.

Some questions regarding the Aleph J:

• Will the miniDsp Flex Eight be able to drive the Aleph without a pre-amp?
• Any recommendation for a chassis that can accommodate 4x of Aleph J (both to space and heat)?

Free.....with Free U.S. shipping (lower 48)

I've been using this streamer for years and it's a great sounding piece that works with a free app from roon called 'essentials' it also works as a roon endpoint if you already have roon.
Here's where you need to pay attention.....since I upgraded my phone (S24)
the app no longer connects properly to the router (sometimes it does, then drops easily others not at all) I've tried everything possible (for me) and just decided to get a new streamer (cambridge CXN V2) that I'd been eyeballing that was half off for refurbished unit (1 yr warranty) on the cambridge audio ebay site. The new Cambridge unit works flawlessly so that rules out the router.
I don't know if it's actually the phone or the unit....tried full reset to no avail. Support for this app from roon is non existing and elac isn't much help either so you'd be on your own......If you already have or planning to get full roon it may work no problem with that.....or it may just be you'll set it up and will work flawlessly on essentials.
Worse case scenario if it is bricked (and not repairable) the case is really nice and one could probably gut it and fit a raspberry pi inside.

To give anyone interested a fighting chance I'll collect names (pm me) for say a wk and pull from a hat at the end.

Free/Free shipping (lower 48) is about giving something back to the community.

Bob

As we can see in several current threads running 3d simulations to support speaker design is growing. Unfortunately the insights they bring are scattered all over the place and missed by most. Should we collect them and present in a coherent form that allows people to confirm the results and add to a growng body of work?

There is a current thread on approaches to on-wall speakers (happy to make a contribution). There is little on the vibration of cabinets (happy to make a contribution). There are threads on the details of ports (happy to make a contribution but not immediately). There is quite a lot of existing work on horns/waveguides. There is a current thread on speaker/baffle shape. There is a little bit on room acoustics. Etc...

A related topic to presenting and discussing the insights from 3d simulations is how a hobbyist can generate 3d simulations of speaker designs using freely available open source tools in a reasonably efficient manner. There seems to be a remarkably low level of activity and I am guessing it is because people are unaware of how to do it. Of course many have no interest in this sort of thing as part of their hobby but I suspect the number of people with an interest is larger than it currently seems.

Hi All,

I have built a couple of amps in the past using either the GPBC block type diodes or the PSU V3 diodes from the store.

I wanted something "fancier" than the block rectifier without going through the hassle (and cost of needed parts) to assemble the diode boards from the store.

So I cobbled together a small prototype board as attached mainly to confirm the footprint etc.

The SOT-227B should fit the perforated base plate of the shop chassis.

I have attached some pics that should be pretty self explanatory.

The boards are 26x39mm , 1,6mm thick and 1oz copper only on the test run and admittedly the resistor positionning is somewhat dodgy, I got lost in the 0,01mm grid in Kicad...

In someone is interested in a couple of boards for a built and willing to give me some feedback I'd happily send a couple of those out.

If this raises enough interest I could offer a group buy (of slighly modified boards in 2mm and 2oz) incl. the IXYS diodes for around 50% of the price at the major distributors (fellow DIYer has lifetime stash of those for whatever reason).

Looking forward to you thoughts.

EDIT: Pictures comming in 2nd post, forgot to crop them...

as with measuring loudspeakers with REW/TrueRTA/etc. and a mic by:using an exciter coil as described at Github as 50 turns #26 wire on a single coil
(Strat/ Jazz bass bobbin) - there's a series resistor (value?) with the exciter coil and the coil driven by an amplifier

The exciter coil is placed against the pickup under test. The output of the pickup is terminated with a load like it would see from a guitar's pots and external amplifier input impedance. (some cable capacitance might be added to evaluate effect))

The pickup under load's output is fed to the audio interface to be evaluated by swept sine.

OK? - any mods to the exciter coil? - how much R in series with the exciter coil?

I need to find a cheap domestic source for the bobbins.

I sent my pair of GPA Altec 416-8B to Troy Crowe for testing. https://josephcrowe.com/blogs/news/altec-416-8b-in-100l-sealed

As you can see, due to the sealed box size at around 70Hz they probably won't play at much above 80db, if that much, at 11 feet away.
I thought of using a pair of these subs. Rythmik Audio servo subwoofer 12" F12SE Signature Edition

I'm well aware that the 416s were designed to be used in larger and ported cabinets. However, when these were built in 2016 I was following the lead of fellow diyaudio.com member Gary Dahl, who in order to minimize distortion levels put the 416s in those sealed 3 cu ft boxes to limit their low end response, and then extend system response using Acoustic Elegance subs/passive radiators. https://galibierdesign.com/wp-content/uploads/wa-trip_gary-d.jpg

But Gary mentioned here last year that he only uses the subs for home theater. For music, he claims to get ample bass response from room gain due to fortuitous speaker placement. I doubt if I will get that lucky in my room, hence my questions about using the Rythmik subs.

Until Troy Crowe builds the rest of the system-probably using this horn 3D CAD files --- Horn No.1994 -- ES450 Biradial for JBL 2446 2" Throat -I will have no idea how well the Altec midwoofers and the Rythmik subs will sound together.

I guess my main concern is if there will be any big tonality differences between the 416s and these subs if I'd have to cross at around 80Hz. I suppose the only way I could cross lower would be if I was satisfied with moderately high SPLs (~ 86db?) from the Altecs at ~ 70Hz in my 2660 cu ft room, however likely that would be. Equal-loudness contour - Wikipedia

I wish to step up from my two sealed DCS205 8" subs. They do a fine job down to ~27Hz in room, but surely they aren't quite endgame. I'm going for two subs again, around 40 liters per box, under 1000€ in total. I prefer sealed with DSP (MSO is great) and I do appreciate response down to 20Hz even if the content is scarce - shouldn't be a problem, considering my experience with the 8 inch subs.

There seems to be plenty of nice options for the drivers, but it's difficult to pick one in the absence of Klippel reports or even repeatable HD tests.

Browsing for subs with a strong motor, reasonable Xmax and low end extension I landed on the RSS315HO-44, which seems to reach very deep naturally (Fsc/F10 36/22 Hz) and scores even better in HD at hifi-selbstbau than the highly praised SDX12 (another great option, though expensive). @mayhem13 has mentioned the HO-44 making noise in high SPL use which might not be my case, but it does make the HF-4 a more reasonable alternative. It doesn't quite have the natural low bass at 45/26 Hz, but not bad either, and scores almost as well in HD.

I then wondered if I should go for two 10" units instead for force cancellation. I browsed loudspeakerdatabase again and came across the Peerless XLS10 830452 which seems like a very well regarded unit. It doesn't model very deep at 49/34 Hz, but the Qtc comes out to just 0.479. Now, I don't know if there's a significant benefit in "natural" low end extension - surely there's some benefit in having the impedance peak where output is most required - but it occurred to me that the low Q "allows" adding mass to the cones. 30g extra gives them a Qtc of 0.626 and similar extension to the HO-44 while requiring less amp apparent power overall. Seems like a cool idea, but no idea if it's worth the trouble. SW26DBACs would be another commercially proven choice for dual opposed and no extra mass required, but looking at the AudioXpress Klippel results, I feel like the cost isn't quite justified.

Next I remembered people praising low loss suspensions for "sound quality" or "chest slam" - my alternatives so far fare pretty poorly in that regard. I browsed again, and came across the SB34SWPL76, which models similar to the HO-44 while having a lot looser suspension. Not a fan of the cone to frame ratio, but it's not a significant problem. There's little data on the performance, but it does have me curious. I wasn't surprised to also find stuff like Wavecor, Scan-Speak or Peerless NE series when having the criteria for Qms or Cms. If I could find the Klippel proven 32W on sale, I might just splurge on those...

Any suggestions appreciated, though I don't see much use in "I've used X and it sounded good" 🙂

Can I do this without releasing any magic smoke?
Half of me says yes, the other half tells me 'interesting' things will happen.

My P's SAP15's have died in my A5 amp the N's seem ok, does anyone know a reliable source for these or is fleBay going to be filled with fakes?

One is Rega’s Elicit the others Arcam’s SA20 and a Naim XS3. What are you learned members here thinking of circuit layout and component quality? Which one would you choose?

A long time Speaker builder and engineer, member of the AES, author of Loudspeaker Modelling, need to post something before I can post a direct question!

I have a Musical fidelity V Link USB to SPDIF converter. No matter which Dac or which computer (Mac or windows) I use, the output locks only at 48khz. All my music is 44.1khz so the highs sound rolled off in this situation. It's the V Link 96khz model and I don't think it has any drivers for either windows or Mac. When I connect the unit for the 1st time, windows automatically installs it. Tried changing the sample rate to 44.1khz in the Audio Midi set up but insoite of everything the Dacs lock the sample rate at 48khz. Please let me know if there is a solution to this. I am unable to reach Musical fidelity support from their website to check on the issue.

I have an old diytube getsetgo single-ended amplifier. It uses a 6.3V valve rectifier that shares a heater with one of the output valves (6A3). The rectifier valve came to some cataclysmic grief in terms of a cracked envelope. The design uses a cathode bias for the output stage. The bias resistors on one channel then burned up and the bypass capacitor got a hefty bulge. I've replaced the resistors and cap on that channel and there is still no sound. What else do you think got worked when the 'event' happened? Hopefully not an output transformer!

Thanks for any thoughts.

Hi guys!
I'm totatlly new in this field, I have done some research to learn the best cabinet I would build for my pair of chinese speaker 4" Aucharm DG-403 (1PCS 2019 New Aucharm 4'' DG 403 Full Range Speaker Driver Casting Aluminum Frame IIR Surrouding Mixed Paper Cone 4/8ohm 25W|Speaker Accessories| - AliExpress) which doesn't have many technical information on the store . So far, I found the TL more interesting, locazating the speaker 1/3 of the legth of the tunel to avoid the dip. So I used python to calculate dimensions given a design that I liked. According to the store the Fs is 72hz, so I end up with these two cabinets, the left tunned to 72hz and the right tunned to 50hz. I got a TDA7377 amplifier and a preamp with ES9018 decoder DAC with 12AU7 tube used probably for buffering. Every sigle piece of this system I found doing researches on youtube and forums, I'm completaly new in this field, therefore, I would appreciate so much any suggestion.





Cheers from Brazil.

I have a few hundred of these for sale.

$1 each (min purchase of 20).
Shipping at cost!

The KSC2690A is still widely available at both Mouser and Digikey.

PM me if interested.

Thanks!

Title typo - PHYSICAL transformer hum.. oops.


I'll be having a look the hum from my NC 2125 soon-ish, so thought I'd get any advice and suggestions from more knowledgable people than me.

I've tried it in a couple houses, with a Audiolab DC blocker, and it's the same in all cases - An audible vibration hum from what i can only assume is the transformer. Certainly sounds like it anyway. This is accompanied by a hum from the speakers, it's been a while since I used it but from memory it's a similar frequency. The speaker noise is low enough that the gain level can be reduced on the back of the amp such that it's barely audible, but all info helps eh.

It's been mild enough that placed in a storage room next to my listening room the last few years i just don't notice it, but now it'll be going in the living room in a new house it's audible enough to hear (and annoy) on quiet days.

Me: I'm capable of identifying parts, replacing larger components (SMD aint my level yet really) and have a very basic understanding of how an amp works, though not to the point where i can say anything more than 'the round thing is the transformer and the big caps are probably the filter caps'. I'm confidant and safe working with mains equipment.

So, at some point I'll be opening it up - what would you suspect? Transformer replacement? I don't know how old the amp is, but it's been about a fair while. Possible the varnish-like compound on the windings has decayed enough to allow it to vibrate?

Somebody a while ago suggested replacing the filter caps - this would be a cheaper easier first step, but I can't quite remember who suggested it and why, so thought it worth asking you who know.

So - any ideas would be really appreciated, where to start, common causes of such a hum, and potential fixes and their likeliness of being the cause.


Thanks for reading,
Jon

My mate wants some help with his sound proof practice room and I want to make sure I'm on the right track with my advice to him.
He's a muso and needs to practice for a couple of hours each evening and more on the weekends when not doing gigs. His playing sax disturbs his wife who works from home.
I'm next door and I can hear him strangling cats when I'm in the kitchen also.
He is currently using his steel portal framed - steel clad shed and wants to stick build a small practice room inside it, but he also wants to be able to record his practice sessions to share with his music teacher and do demo tapes etc.
He is a carpenter so no problems with construction.
I've suggested framing up and cladding the outside with thick MDF and stuffing the space with rockwool or acoustic FG but not lining the interior with board, instead using a sound transparent heavy fabric to reduce bounce and reverb.

I've also suggested the usual practice of unequal dimensions and following the angle of the sheds roof.
Am I on the right track there?