I've looked into Scott's compact MLTL designs for the 7MS and I've found two candidates; the Wooden Design
A7ms Compact ML-TL 0v81 and the Okapi.

Does anyone have insight into the differences between these two?

..
..
A while ago, I published an article on alternative follower configurations :

http://www.diyaudio.com/forums/showthread.php?s=&threadid=128571&highlight=

I said alternative, because there have already been the famous Curl / Borbely followers, both in single-ended and the complementary versions. And they have been around for quite a while now. The recent revival of, and the vast interest in the B1-topology, which I find truly amazing, can only be described as a “Pass” phenomenon !!!

Also in my discrete opamp thread from last year, I commented that there could be better ways to do a DIP-8 unity gain buffer than using an opamp :

http://www.diyaudio.com/forums/showthread.php?postid=1480342#post1480342

i.e. a SMD-B1 on a 10mm x 10mm footprint, using a matched pair of BF862’s.

For sale is my DIY subwoofer. It contains LaVoce SAN214.50 driver powered by the Hypex FA502. The cabinet is 62x62x55cm (HWD) and weighs around 60kg. It is very heavily braced, with roundovers and painted using duratex. Price is £1000 NOT including shipping. I would prefer collection but I am open to the buyer sorting out a courier for this.

Note: the amplifier is unfortunately scratched on the rear, this in no way affects the performance and is purely cosmetic!

I was trying to see if there was a spice model for the TPA3255. I sniffed around TI's site and, on my journey, I have discovered TI has become a walled garden! I look at guys like AD and I'm just flabbergasted that for a company with so many products, TI doesn't have nearly as much support for them (AD even has a wiki). I remember downloading TINA a long time ago on another computer and it was free. What the heck happened?

Hey folks…..modest family room 5.1 system needs some added ooomf. Currently there’s two DIY 10” small ported that give an in room f3 around 40hz. I wanna fill in the bottom to say an f3 of 20hz. My thought was adding a third sub 15”……high excursion high power small box type with 1000w or so…….mix it in with a low pass filter set at 40hz or so with a subsonic cutoff at 20hz…….really narrow passband and have enough current on tap to get the job done…..90db or so at 25hz. Is this the best way to go at this or is a large low tuned ported a better option? The driver have in mind for that would need 4.5cuft for an f3 tuned to 25hz using a slot port equivalent to a 6” round

All,
I'm currently building a TSE-ii for 300b tubes. I'm using the Hammond 276X power transformer, and, at least at the start, the big edcor 5k OPTs. Pictures of the board below. I have the capacitors and transistors mounted on the bottom of the board, and the resistors on top.

I started the checkout procedure today, and the plate voltage on V2 (one of 5872's) is way off - it's currently up around 272 vdc. FWIW, the plate voltage on V1 is fine - I can set it to 175 vdc using the trim pots.

I'm not sure why the plate voltage on one driver tube is so high. I'm also concerned that the B+ might be too low. I'd be grateful for any thoughts and/or suggestions.

Here are some readings:

• With just the rectifier tube in: B+ is 350 vdc and negative bias voltage is -134 vdc
• With the rectifier and the 5872s in: B+ is 275 vdc and negative bias voltage is -108vdc
  • Plate voltage on V1 can be set to 175 by turning trimpots
  • Plate voltage on V2 is about 272 vdc
    • I looked at the schematic and noticed that the CCS array is connected to the plate of V1 & V2, so I took some measurements on the ICs:
      • For V1 (the driver tube that seems to be working ok): there are 144 vdc on the Gate, 275 vdc on the Anode, and 164 vdc on the Cathode
      • For V2 (the wonky driver tube): there are 271 vdc on the Gate, 275 vdc on the Anode, and 275 vdc on the Cathode

Does this mean that there's some issue w/ the IC (IXCP10M45S)????

Also, is that B+ too low? I took C1 out of the board, per the note #1 in the BOM notes.

Pictures from my build are attached. Thank you in advance for any help! Let me know if you need any other info or measurements.
Dan

I have a small carpeted listening room, 10’ by 12’ with 8’ ceiling, and recently changed the position of my speakers. These are the late Jeff Bagby designed Piccolos with an SB Acoustics SB15NRX30-08 5” midwoofer and SB29RDCN-004 ring tweeter. I built these sealed rather than ported, so the bass is somewhat limited.

Initially the speakers were about 3’ out from the front wall and about 6’ apart. They sounded great and had excellent stereo imaging. But I just didn’t like them sitting so far out into the small room. It annoyed me visually so I moved them back against the front wall. Needless to say the sound changed dramatically. They now boom a lot more bass and don’t have nearly the stereo effect that was there before.

The other change is a small 3’ foot high by 2’ wide equipment cabinet has been move to the front wall directly in-between the speakers. Before that there was nothing between the speakers. Just open wall.

I don’t want to move the speakers back out into the room again. So now the challenge is how to get them to sound the best possible and improve the imaging even with the compromises against the front wall.

Does that mean just electronic compensation to de-emphasis the bass or are there some other things to consider as well? Any suggestions are welcome.

Hello, I recently acquired a used pair of YG Acoustic Carmel and have been driving them with F4 monoblocks with a BBA3 preamp and 32 volt rail dual mono power supply.

I currently use a Gold Note DS-10 streamer/preamp as my remote volume control and set my BBA3 with Goldpoint 4 gang attenuator to full volume.

I have a two part question.

- instead of turning up the BBA3 volume all the way and not utilizing the pot, is there any harm in removing the pot and having the BBA3 preamp run solely as a full output front end and continue to use the Gold Note for volume control or build an Academy Audio Muses control which I have all the parts already? I could use a tad more gain but the Gold Note is only 2V.

Also, what would be the easiest device to buy and software to adjust P3 on the BA3? I would like to add a little harmonic distortion and set each P3 the same. I saw Focusrite scarlet as an option. Is it best to set each balanced channel or each V+ and V- for Left and Right.

Thanks.

I’ve trashed my shoulder and have five unproductive weeks ahead. A lot of time planning and to finally finish half done projects. Will first build a 807’s stereo pp Amp with 7193 preamp and driver tubes. Basically a Williamson w2. Now I have a second one ahead of me.

Just got my hands on two NOS Svetlana 6AS7G. Have matched 6SL7 and 6SN7’s.
The 6SA7G is in my guitar amp eyes kind of strange tube with the low voltage/high currant thing going on but a lot of people seems to enjoy its sound
Not a hifi connoisseur but would like to have a nice hifi stereo amp. Not separate mono blocks. Vinyl playing mostly and have most parts except for transformers. Don’t want to spend a fortune on those. What type of circuit should I go for? PP or SE (PP less expensive). Read that those tubes can be hard to drive. Any ideas appreciated and also if anyone will be willing to share a schematic. Got this with a 6SL7 as v1 and 6SN7 as V2 and parallel 6AS7

My radio cassette player in My 97 Saab 9000 with OEM hardon Kardon .setup 10 speakers with a large discrete amp under passenger seat.
A seriously expensive system.. back then 🙂 It has worked V well for decades. I'm happy with it's sound .
Really Not wanting to retrofit some Disco era Contraption with dozens of Useless to me 'features'. And sketchy sound.
But my unit is now going intermittent.
IE; Tapes work as normal, but radio (all bands ) makes dead silence.
Curiously IF I play a tape for a half hour then the radio section comes alive. again and typically remains useable for several months to a year.
Sometimes only for a month.... No idea as to cause
Very strange. ALL wirings /connections have been checked . Not a loose connection issue.

Anyone have a circuit diagram.. for the head unit?

OR at very worst.... a suggestion for a Simple elegant Euro style head unit?
Cassette capability is unlikely and Cd s' are dying out as well. SD /USB intrigues
But how does one access the myriad files tracks without a monitor screen?
Zero interest in linking a phone or streaming. That even possible ?

Hello, I'm looking for a diy project inspired to the popular Klipsch Heresy III or IV loudspeakers, of which I like dynamic capabilities, similarity to live sound and a kind of mid-range punch never heard before. What I don't like is uncertainty about time-alignment between mid-range and tweeter and the quality of woofers, components and cabinets.
I would be really grateful to anyone who could direct me to a similar project on which I could apply checks and customizations.
Thank you very much.

Selling my Onix X-LS Classic speakers. These sound very nice actually. The woofer is very light and agile. Very nice tone to these. Am moving, and have too many speakers anyways, so these are up for sale. The cabinets are gorgeous with real wood veneer, but they do have some cosmetic imperfections. One one side of one of the speakers, there's a pretty big scratch, that doesn't ruin the look of the speaker by any means but is definitely noticeable when viewed from that angle. From the front though, they look perfect

The X-LS Encore kit I believe sells for over twice my asking price here, which is just for crossover parts, cheapo posts and drivers. It is the updated version of what I have, with a different tweeter.

I'd like to get $175 plus shipping for these

Hi,

I am helping a friend out with his Fender Blues Deluxe from 1993. Ive replaced all the capacitors in the power supply, and all the voltages going to the different sections seem right. But I do have a question about the filtering section. Capacitor C35 only has around 50vDC when powered up. Is that how it should be? Also, I measured the resistance over R83, and it was well over 220k when in the circuit, but when I lifted it I did measure the correct resistance.

These are just two things I noticed, that hopefully understanding why will help me learn a bit more.

Thanks

I need help whit resistor r352 what Valium is burning and can't read whit my ohmmeter because is completely blowout or burning

One of the input transformers in my ESP9s is fried. Dead short. Does anyone have a spare to sell?
John

I'm considering acquiring JBL Control SB-5 box. I assume it's unloaded. At the moment I've got 6.5" woofers coming out of my a$$. I've no experience with 6th order. Can I throw in any four (matched) drivers and adjust the port tuning accordingly?

2 sets of transformers, 125.00 each ( two outputs and one power) plus shipping and paypal fees if used, perfer friends and family. Personal check OK.Local pick up in Danbury TX if local. These transformers sound very good and have the light color metal if that means anything. I can get one set in a medium flat rate priority box for 18.00 to lower 48.
Thanks for looking OB

I joined due to this thread: https://www.diyaudio.com/community/threads/adcom-gfp-555-upgrades-from-audioxpress.277484/

I just recently got into "HiFI" or vintage stereo gear from the 80s and 90s. I've been pretty much focused on Adcom and Cerwin Vegas (I know, many don't like them but I love mine). Anyhow, I love my GFP-555, but I'd like to upgrade it - mainly with a remote control for gain/volume.

I keep finding references to an article by Charles Hansen, but like the OP in the linked thread above - I can't find it anywhere online.

Any help would be appreciated. I'm in the process of picking up a second GFP-555 (might be a 555 II) off eBay that needs work, and thought it might be the perfect candidate for this project. As a HAM, I'm not afraid to use my soldering iron 🙂

Thanks for the input! Looking forward to yet another forum to use.

I have an Eicor 600 ohm to 15K center tap matching transformer could the 600 ohm primary as
the output and use just one side of the 15K center tap as the input. Wouldn't that be 7.5K to
600 ohm and give me a voltage reduction of about 2.5 ?

I have a thorens td135 which I am lamely attempting to put right. I have improved most things including replacing the difficult rubber insert inside the end stub tube inside the bearing housing - very fiddly. Alas I am a complete amateur when it comes to electronics and the motor, working approx 5 days ago, now doesn't so wondered if the cap shown might have failed - it is a little sticky inside the blue area? I wonder also if I may have tugged/pulled too much on the wiring when moving things around causing a break but I can't see anything unless of course it is in the motor itself? Thanks for your help in advance
Steve

Long story as to why I have a spare, but if your 104/2 is missing a bass port flange/horn/thingie, I have one for you if you'll pay the postage.

I have 2 for sale at £150 + p&p each .

Both working perfectly.
No longer needed


Uk based .

Hello forum 🤞🏻

Ive bought a DC 300A II to power my 4435 monitors in a propper way.

So far i changed the Fuse for 240V (Buss MTH 5) as reqired in the Manual at Page 14

In Germany here we have 230V 50Hz

What shall i choose 230V or 240V?

Maybe someone can give me a step by step to wire Everything correctly.

see atached Photos


It would be great to get some hints 😊

…and yes i Know the thread about the 300A, the MK II looks a Bit different.

Made according to https://www.diyaudio.com/community/threads/dac-ad1862-almost-tht-i2s-input-nos-r-2r.354078/
Live music performance!!!!!! better than https://magnahifi.com/holo-audio-spring-iii-dac-level-2-r2r-dsd1024/
price 799€

Hello, can anyone help me with finding schematic manual for EAD DSP-7000 mk2? OR MK1 at least . . I have a dead transformer in this machine and
need to find our secondary voltages for making a new custom transformer. Thanks!

I'm new here at diyAudio and I'm playing around building audio circuits I need help finding some info on this transistor.
Thanks in Advance Aaron

Hi all,

I've been out of action for an unexpectedly long time but have finally managed to get back to audio.

I got one of these locally advertised as being in working condition and it did work, after a fashion. the controls were obviously dirty and it seemed to need a couple of hours to warm up in order to give reasonable measurements.

I initially recapped the power supply ( as it was easy to pull out the card), the thing is otherwise built like a tank; lovely quality actually.

I am aware it's not the last word in distortion measurements but I like it's tactile nature and if nothing else, the notch filter and distortion residual output can be used with my soundcard based measurement system as a good quality preamplifier

The issue is that the residual output is noisy and shows mains related modulation.

I've opened it up again to re-cap all of it and have discovered that the carbon composition resistors it uses in presumably non critical locations all seem to have drifted high, out of tolerance.

I'm therefore rebuilding the boards one by one, starting with the easiest to get at, the Rejection Amplifier PCB no. 00333-66503. The circuit diagram is on page 67 of the service manual: https://www.davmar.org/pdf/HP334A.pdf

My first question is for some reassurance, I'm planning on replacing C13 & C15 (500uF 15V Sprague axials ) with 1000uF 50v jobs as the old ones are so huge that I have space and reason that doubling the size of the output coupling capacitor and the feedback capacitor won't deleteriously affect the function of the circuit. If this were an cap coupled audio amplifier I would not hesitate but test equipment is above my pay grade at this stage and there may be subtle factors or interactions at play that I am unaware of, any comments please?

The second question is about the tantalum capacitors (C3 and C6, same page of service manual) that filter and bypass the power rails, they test fine but I want to replace them as a precaution, they are 3.9uF 3v jobs. I've read on datasheets for three pin regulators that "an output cap of 1uF tantalum or at least 10uf electrolytic may be used". Is there some sort of convention whereby a tantalum cap should generally be replaced with an electrolytic of ten times the value in power supply decoupling?


With thanks,

How do you run your amps? Are they plugged in only for listening sessions. or have you rigged in a switch of some sort? In the factory config of amp on bottom, these things running all day long running hot as Hades , even with a fan, is not really agreeable to me.

Let me know how you run yours. I am about to embark on refurbishing mine one way or another.

Hello,

I trying repair an amplifier

When i got it amp unit was short circuited, burning transistors

- changed many parts and got it running except bias reads ZERO!

So bias is 0.00v and doesnt react to the trimmer

- bias trimmer pot is tested and ok, resistors attached to bias circuit are ok, capasitor in bias circuit was changed

- dc offset is within limits and reacts to trimmer

- transistors were changed and tested too (with cheap component tester)

What could be the main causes for bias to stay at zero volts?

Apologies if this is the wrong section or has already been asked a million times...
But i guess i'll start with my easiest question first:
So i previously recorded 4x vinyls before addressing the over-speed problem of about 3%. (Replaced the belt and modified the drive pulley diameter).
So to avoid having to re-record another 4x times, i'm guessing it would be easier to simply adjust the speed in audacity using the 'change speed' command?
https://manual.audacityteam.org/man/change_speed.html

I'm certain that I WANT pitch to change as well, so i think its the right tool, but i'm not an expert in Audacity. I'm just a little uncertain as to what this does to the sample rate... I'm assuming that decreasing the speed would increase the sample rate? Though since i originally recorded at the maximum rate, would this not be possible? Causing audacity to do some kind of down sampling to make it fit?

Or is this just a fools errand and i should just bite the bullet and spend a few hours to re-record them? If so, would it be best to record at normal 45rpm, or can i get better performance if i record slower at 33.3rpm and then increase the speed to 45 in post? Or am I just wasting even more time? 😅

Though I kind of wanted to avoid re-recording as i'm a little bit time poor right now, but i will need to return this turntable either today or next week.
(Unfortunately i dont have my own TT, plus i'm moving house atm so its kind of my last chance).

But also i kind suspect that constantly playing these records is wearing them out and is introducing more and more surface noise? i can upload some files later today to demonstrate. (Large file sizes)

Thanks 🙂

Hi I have dismantled the BTD 12S tonearm on my Thorens TD135 , it needed a new rubber insert, but in doing so one of the securing screws pinged off into the ether. Does any one know what size these are please? Yes there is a second one but I have refitted it already and don't want to spend another hour or two trying the niggly refit again!! The photo shows where the screw will go
Thanks

Steve

Just like the title says. As precise/quiet and as small as possible. Build or buy?

Recently I've been reading up on the importance of a (somewhat) constant directivity. A waveguide can be used to narrow the beamwidth of tweeters to match the midrange at around the crossover frequency. But waveguides also help limit edge diffraction AND make phase integration easier (Z-offset between mid and tweeter will be smaller). So three benefits for the cost of a bit of plastic (or aluminum).

So why are waveguides not much more common? Is there some drawback I'm missing?

Hi all!

It has been my intention for some time to make a multiway digital crossover with minimal parts. I have designed a tiny little DIP-24 board featuring two onboard CS43131 DACs, MCU, regulators and level shifters. The schematic pretty much follows the Cirrus reference designs.

The CS43131 has one first-order IIR and three second-order IIR filters that should allow for "simple" crossovers and perhaps an EQ.

During boot the MCU sets up each CS43131 into a default i2s 24/96 mono mode expecting a 19.2Mhz clock on pins MC1/MC2. The master clock is then derived using the internal DAC PLL for whatever frequency setting is required.

Shortly after boot the external level i2c (3.3v) bridge becomes available for further configuration. I hope to develop a simple Arudio lib to edit the clock setup, audio source and output filters.

I am expecting the delivery today of a test board featuring a SiT8208AI 19.2Mhz clock and XLR outputs.

More to follow!

CS43131 - Dual Mono Configuration
https://www.cirrus.com/products/cs43131/

5x Toshiba TCR3RM Regulators ~ 5 μVrms
https://toshiba.semicon-storage.com/info/docget.jsp?did=69842&prodName=TCR3RM18A

Level shifters
to 1.8v for i2c, i2s, dsd clocks and data

Boot and config MCU
Cypress Semiconductor

I have a unique need and have not been able to find a solution anywhere. I have posted this question to more appropriate sites and have not had any luck so I'm crossing my fingers here. I recently designed and constructed a one-off. Outdoor rock speaker housing and I have been unable to locate a suitable speaker for it. It would need to be 8 inches in diameter. Preferably, full range or mid-range appropriate for outdoors. And be able to be mounted from the back to the front. Cause that's the way I made the speaker housing already. I would like to keep the cost below $250 but at this point I may have to take what I can get. For an idea of the housing I used an OSD rock speaker at a rough design guid. It weighs approximately 65lbs and is sealed with .75ft³ Thank you for any help you can provide.i work in the custom composite industry and this was an all hands on deck shop project. One of the layers of the rock is Titanium coated diamonds just because we had it and didn't have another use for them (pretty amazing actually) attacked is the OSD I used as a guide.

Dual trace build for oscilloscope and cellphones
Schematic on build
Please comment
PDF copy is clear

I have a recently acquired 1987 Marshall Jubilee (model 2550). I've recapped, retubed and rebiased it.

The amp is a "sort of" channel switching amp. There's no independent EQ but there is a "clean channel" and a "lead channel". The lead channel introduces an extra gain stage and a diode clipping circuit. The amp has one weird behavior -- when on the clean channel, there is distortion that fades in and out / level jumps but only when the lead master pot is up. With the lead channel volume pot on zero the clean is perfect.

Here's the relevant part of the preamp schematic. Circled in red (because I think they're relevant) is the lead master pot, and the switch (actually a relay) that selects the channel.



With the switch in the position shown, the amp is on the lead channel.

The input signal comes in via V1A. The clean route goes more or less directly (ignoring the "rhythm clip" circuit) to the grid of V2A. The lead signal goes to the grid of V1B, and the signal off V1B feeds the diode clipping circuit and passes (via the lead master pot) to the grid of V2A.

When the channel switch flips to clean (the other position, not as shown in the schematic) the effect is to ground the lead signal heading into the diode clipping circuit and also to ground both sides of the lead master pot.

My thinking is as follows -- if both sides of the lead master pot were actually, properly grounded, the position of the lead master pot could not make any difference to the signal downstream as there could be no signal at the wiper of the pot. Since the position of the lead master pot does make a difference to the signal downstream, the assumption that both sides of the pot are grounded must be incorrect.

Therefore that channel switch (which is actually a 36-year old relay) can not be properly closing and grounding the signal and that component is likely the cause of the problem.

I'm not an experienced amp tech by any means, so any comments / critique of my thought process so far would be very welcome!

I'd like to add a small screen and a not-ugly case to my raspberry pi streamer (uses volumio). The only thing close to the aesthetic I'm thinking are the sold out ones here. Not sure if aluminum or steel is more commonly used.

Does anyone know of a company/source for the sort of machined metal style cases?

There's probably a proper word for this aesthetic/era but something (anything) like this:

Hi all,
I am trying to get a test circuit up and running based on this chip.

https://www.diodes.com/assets/Datasheets/PAM8019.pdf

But i am not having much luck at the moment

Here is the input signal to the amp.




An here is the output signal to the speaker which i get no sound from and a very suspect square wave.




Any ideas what might be going wrong here to give such an output?

Notes:

I have left the PL pin unconnected
I have not implemented any under voltage protection as i assume this is optional.
I have connected pin 8 directly to VDD 5V rail

I'm looking for a tweeter or two for Revel Performa F32, from about 6 years ago or so. Revel no longer stocks them.........and I hate to lose these speakers! Thanks David

This is for a hagerman bugle 2, that i have modified. the biggest mod is that it now runs off of 2x12V NiCad battery packs. It is dead silent.

The front has an on/off switch. When its off, you can press the button to get a readout on the battery's voltage. Anything around 24V is fine.

Opamps are LM4562, i dont know if they were the original specified opamps. They are DIP8 pkg, so should be easy to roll your own.

Charging the batteries, when needed, is simple. Open up the case, the batteries have easy quick connectors. Just hook it up to your charger (not included, but they're inexpensive) and charge one at a time. See circled section in the picture. The current draw is small, so you dont need to charge often.

soldering isn't my best work, so I'm open to offers.

$125/open to offers

Dear Music and Audio Friends,

Solen has simulated three different crossover options for my Purifi PTT5.25/Beyma TPL-75 Project.



#1: Both legs 2nd-Order Linkwitz-Riley, crossing over at 2400Hz.



#2: Both legs 3rd-Order Butterworth, crossing over at 2400Hz. The arrow points to the little bump at the 2400Hz crossover frequency. Which Solen would rather avoid, I take it.



#3: Low-Pass: 2nd-Order Butterworth, crossing over at 2400Hz; High-Pass 2nd-Order Linkwitz-Riley, crossing over at 2400Hz.

If anyone wants to see the complete workups (driver specs, parts lists, schematics), please let me know.

All thoughtful comments welcome.

john

Hi,

So I have a 12" PA driver with a .38 Qts; Fs: 42 hz and EBP = 110 so BR advised. Vas : 113 L, limited Xmax : 7.5 mm : again in favor to BR load choice

Is there bass alignement that are adived based on the Qts driver number ? The Qts seems too big for a SBB4. Not sure a Bessel is the best if transcient (group delay flat enough) is what matters before low pass (passive) filter tweaking not talking about a Fb at 10 hz below the driver Fs if Bessel BR load is chosen !

Which alignement filter would you choose as a start (before low pass filter tweaking) with such Qts which is at the limit before flat and non flat alignement.

My basic understanding is room gain in most of the rooms doesn't really matter above 80 hz, yet matters belllows. Seems most of the time a smooth anechoic magnitude is good enough for most rooms. Something more close to the sealed 18 db slope. (so with BR slope nearer to 24 dB than higher BR slope)

So following that idea, still with my basic understanding about BR load: bigger sized box and more gentle slope.

I admit such a driver should be used as a uper bass-midrange driver. BUT, in an average listening living room, it is "maybe" large enough despite high Qts 42 hz.

What BR alignement would you use as a start before filter tweaking (group delay flatting) if transcient is favored as well as second order low pass filter ? Qts is increased with 0.5 ohms with a good coil and some length from the amp? SSB4 (more advised with Qts near 0.32) ; Bessel (but very low Fb) ?

BR : -F6 is circa 45 hz ; sealed : circa 78 hz.
BR : -F10 is circa 35 hz ; sealed is circa 45 hz.

Again, room gain seems more important below 80 hz in most average living room. And often we have to focus on the 80 hz to 200 hz for that tigth slam psychoacoustic wanted sound (again my basic understanding; Stereophile measurements, etc)

Which trade off BR alignement would you choose going with a passive filter with such driver datas for a bass driver in a 3 ways, please ? (as a start before group delay flattening with a second order passive filter).

My main concern is to use this 12" PA in a living room as a bass driver with a low pass from 200 to 300 hz and making strong enough the 100 hz to 200 hz area where the snap, tigth feeling is.
As going passive I am of course worried about the high pass slope I shoud use for the midrange above!

Hope it is not too much confusing question.

Edit : better to change the driver or at the opposit going active amp with DSP (but I fear the group delay when playing with IR bass boost with such low 7.5 mm Xmax)

Hi all,

I created a new forum where we can discuss about all of the Erhard Audio Dynaco PAS upgrade kits, https://www.erhard-audio.com/EA-Forum/index.php
This forum is very new, so there are not many members as yet, but there are a few posts covering some updates and changes we've made to some of the upgrade kits.
This is an exclusively Erhard Audio PAS upgrade kits forum only, for any general Dynaco PAS preamp questions or other make/brands of kits, it is best to keep discussing those here at diyAudio.
I look forward to seeing you at our new forum.

Holger
Erhard Audio

ps. yes, I did get permission from diyAudio to post this 🙂

I'm trying to repair a dead Meridian 500 transport for a friend (VAM1205 version). It came to me with two faults:

1) Badly struggling to eject and close.
2) Failure to read discs.

I've now got the drawer action working well but it still doesn't read discs even after I replaced the optical block with a brand new one.

With a disc loaded, if you press PLAY you get the message 'LOADING' on the display but sod all happens, no disc rotation at all. This was the same with the old optical block too.

I haven't been able to find a copy of the service manual so I'm flying blind with this one. If anyone is familiar with this machine and knows of some common failure modes I'm all ears! You might save me a lot of trouble.

Looking for some SB Acoustics SB65WBAC25-4 2.5" Full Range. New or used must be in good condition.​

thanks!

Hi: I've searched for this particular symptom without much luck. Hoping for ideas.

This repeated sound suddenly appeared when playing a CD. Sound is a group of five (?) quick ticks that repeats when playing CD. It is quiet between tracks.

Affects all my commercial and home-recorded CDs.

I'm quite sure sound is electrical not mechanical.

Tick sound appears on all tracks and in both channels.

Player works properly, gets a TOC quickly, fidelity is normal.

Tick sound level is well below music level but easy to hear.

Tick sound appears in RCA and headphone output. I haven't tested optical output, I don't have a converter.

I replaced laser ~10 years ago.

Anything I can add? Thanks in advance,

dizmayed

I've been reading up a bit on feedforward networks. Seems like an interesting approach, but I can't think of what I would use it for. I know benchmark amps use them and is apparently a talking point for them. How are feedforward loops applicable in audio?

Hi friends!
So after a long journey playing around with analog, I'd like to turn my eye to this DIY Dac I got from a former DIYA-member.
Problem is, I need some conversion.
Source is a mac mini 2018, with either USB or HDMI out, and the dac only has that SPDIF RCA plug.
I've found some cenverters, M2tech for example, most are way beyond my budget.
What's my options?
Can I connect something HDMI to RCA?
Is there a simple DIY jig available? (I am not very good at electronics, and nothing in digital, although I build a few things...)

thank you!

I'm trying to help my friend fix an overheating problem with the voltage regulators, causing instability and crashes. We know improving airflow will resolve the problem, but I'm trying to find a way to improve overall dissipation capacity as well. Could I use a thermal adhesive to glue longer metal strips to each fin of this heatsink to improve its dissipation capacity? That seems easier than trying to remove the heatsink and install a larger unit onto the chips directly. Thoughts?

I'm a bit puzzled on the PCM1794a Mono mode: it's clear that in Mono mode, the one channel's analog output is inverted to allow balanced operation. However, it's not clear on WHICH channel is inverted! Absolute polarity is important in my application as I'm building interchangeable DAC cards for a DSP application where the polarity needs to be consistent.

When the DAC is set to Mono mode left channel, I would presume the right channel's polarity is inverted, and vice versa for the other way round.

Table4 on p17 stipulates that a digital full-scale positive is represented by a full-scale positive voltage output when using the datasheet standard opamp I/V and summing circuit.

The Mono mode in Figure27 p22 then shows how the output of the Left output in Mono mode is called "OUT+" yet it goes to XLR pin3/cold.
Similarly the Right output is called OUT- but goes to XLR pin2/hot.

The question therefore is:

- In mono mode, is the polarity inversion applied to the opposite or selected channel?
- Does this mean for a dual-mono application with 2 identical circuits but one strapped for left and the other for right, the one channel would need to invert its polarity at the XLR plug to retain phase?

I have a power supply set up available which can give me +/- 68V. The power supply consists of two 500VA toroids and two banks of eight 22000uf capacitors.
I would like to put it to good use and am looking for any suggestions for amplifier modules to use with it.
any suggestions would be appreciated.
Thanks

PM

PM

The acoustical path lengths/end corrections leave a big notch at/above 3 x Fb?

This project, like most DIY, is based on the work of others. Nelson, Zen Mod, Ben, Mikey and Lynn, were all a huge influence on this project.

Starting with Nelsons 2015 Sony VFET front end, further modified by Lynn for his version of the XA25. I have been using this front end on many amps as it gives a nice 20dB gain and has an adjustable harmonic spectrum. I normally set it for minimum H2 and let the output stage add the honey. I have this frontend driving one of ZM’s DEF R3 output stages, a big SIT-Mu Follower, a ZM Redneck DEF with a Pass SIT1 and now the Choke Loaded Follower. This has helped me in evaluating the output stages as they all have the same input/gain stage.

This Choke Loaded Follower is following Nelson and Mikey’s work and then all of Bens excellent posts. It does incorporate a buffer for the SIT. At first I was concerned about this additional stage but it worked so well in ZM’s DEF R3 that I figured I would give it a try. It’s a good thing. IMHO It add additional speed and transparency over direct dive of the SIT and the bias is nice and stable.

The reason for this amp is for the summer when I need something that dissipates a bit less heat. The Big SIT-Mu Follower is excellent sounding amp but at 185W per channel heats up the listening room. Ben said that he liked the sound of the Choke Loaded Follower and at less than half the heat dissipation it seemed like a good thing.

The caveat with the Choke Loaded Follower is that adjusting the VDS is problematic. You can change the bias and this changes the drop across the choke. I played with different supply voltages and the higher you are, up to about 37v the lower the distortion. 32 volts seemed like a nice compromise and that gave about 30V across the SIT at 2.5Amps. I have included a graph to see how bias changes the distortion with a fixed 32v supply.

Lastly I added Nelsons De-Thumper, just because. I’m sure my vintage Altec 515’s will appreciate it.

Oh I like to see my work, (modern art?) so it’s all in the open. It also makes it nice for adjusting and testing.

I hope it inspires people to try the Choke loaded Follower. It sounds great!

Jim and ZM like pictures so here are a bunch…

I built LW's Transform on a pcb from Rod Elliot (sound-au.com). Pcb no 71.

I used LW's values rather than rod's as these were a closer match for my subs.

These are the lower closed box section of what were once, a pair of ML Aeon hybrid electrostatics. (I sold the worn out panels and crossovers on ebay).

First chart is the ML response without any eq, second one is with the LW Transform in circuit. I installed it into an old Arcam Alpha IIs tape loop.

Charts to follow

Hi,

I know there are a lot of cabinet designs for the Diatone P-610 driver, are the stock cabinets worth considering? Thank you

Started researching a good line stage to match these 1625 power amps. After a lot of reading, stumbled on the low mu approach. The more I read, the more it made sense. So, found this design by Thomas Meyer, which I found intriguing. Was initially going with a 12B4, but I love the sound from octal tubes, so went with Mr. Meyer's design.

The parts cost forced me to re-consider this project. However, after a talk with my friends at Heyboer, found out they could make the iron for a reasonable price.

Since I wanted this to come out great, enlisted my buddy to build it. He is much better at this type of work than I am. My skills are OK, but nothing like his. Since he was intrigued with the design, he happily accepted the job.

The only real change made was using a Khomozo stepped attenuator connect to the input vs. the transformer volume control on the output. Used a slightly beefier power transformer, DC'ed all the tubes, and went with 6DE4 damper tubes.

This preamp sounds better than anything I've ever heard. It's shocking just how good it sounds.

I've been looking at enclosure options for the Markaudio 7MS and CHP90.
Ideally I would like to build one enclosure suitable for both, but I recognise that this might be far fetched.

What I've found interesting is that opposed to a regular BR, some of these more complex enclosures have wide backwave output in the mid bass, mitigating baffle-step losses.
Just look at this one from @nandappe :





And here is a comparable one for the 7MS:



I've also looked at the Okapi compact MLTL for the 7MS: https://www.markaudio.com/wp-content/uploads/2022/08/Okapi-7MS-compact-MLTL-metric.png
Would this achieve some of the same effect? (wide backwave output up to 700-800 Hz to mitigate baffle-step)
Is there an enclosure that would be suitable for both the 7MS and the CHP-90? (adjustable duct length etc)

Hi All,

I am really hoping someone will be kind enough to shed some light on the following.

I don't have much experience with amplifiers and am struggling to get my head around a specific aspect of the data sheet for the PAM8109 chip

https://www.diodes.com/assets/Datasheets/PAM8019.pdf




Pin 4 in the datasheet is labelled as "4 -- Bypass -- Bias Voltage for Power Amplifier"

My 5V audio source is already biased to 2.5V.

My question is:

1. Does this chip accept a signal that has already been biased.
2. What is the chip asking me to supply on pin #4
3. The example application seems to imply that its 0V connected to ground via the bypass capacitor.

Am i good to go ahead and feed in my existing signal, and the bypass pin would only be fed a voltage if the signal was not biased and then would handle the bias internally if a reference voltage was applied to that pin.

I feel like i'm making too many assumptions and just guessing at this point.

Thanks in advance and apologies if i am misunderstanding to the point my question makes no actual sense 🙂

I recently took a chance on this Victor QL-Y7. When it arrived the platter would start to spin but then stop again. The series of switches along the front panel seemed erratic so I squirted them with contact cleaner, whereupon the whole thing stoped working completely. I managed to get one of the switches apart, and the little metal contacts at the bottom were corroded, so I cleaned them up but it made no difference. Sticking a meter across them (removed from the PCB) reveals the resistance when energised ranges from 200 to 400Ω. I figured they were shot, pulled them out and replaced them with new parts, albeit of an entirely different design.

I've replaced most of the electrolytics in the deck now (just waiting for a couple I didn't have). Some of the larger main supply ones were toast.

The platter now turns again as soon as the turntable is powered up, but none of the switches do anything. The two on the motor unit itself, which select 33 or 45rpm, are touch switches which apparently rely on capacitance to work (except they too are unresponsive). I'm assuming the ones on the front panel aren't, as they're plastic, but the fact that the little nipple inside them that bridges the gap between the two metal contacts is made of a rubbery material is making me wonder whether there's something odd about these switches. Does anyone know what the score is with them? I might reinstate them, having now cleaned them all (they're a fiddle to get apart).

I know this is car amplifier, but beside the inverter it is a solid state.

Before i use tda2050 with 24v dc ct inverter in my car, no pcb i solder the resistor and caps straight to the pin as short as posibble. Sounds good, but it is hot and i think it have potential fire hazard.

So, i buy this cheap amplifier and replace most component with a better one. This is what i do:
1. Change all the 1/8w carbon resistor with 1/4w metal film.
2. Replace original capacitor to better capacitor. i use elna re3, silmic ii and panasonic fc. For smaller value i replace mylar with generic mkm and philips mkt. I replace mono ceramic with 2kv ceramic.
3. Replace the original jrc4458 with original ne5532 from ti. Yes, they got both input protected with transistor configured as diode.
4. Change supply for opamp from zener with lm7815 and 7915. I measure the voltage at +15.1v and -14.8v. I use two 220ohm 2wa resistor in parallel before the regulator.
5. Rewind the inverter toroid from 24v to 32v. Replace the original pair of 4700uf 35v capacitor with 10.000uf 50v+1000uf.
6. Add another gain stage before the amplifier with resistor divider at the input, i use ne5532 set around 9x gain. I use shielded cable around 10cm, i also ground the shielding wire. The total gain is around 2.5x. i do this because the source voltage output is to low, if i increase the volume i notice distortion using 50hz test tone.
7. Change the final transistor on the channel that i use for my woofer and tweeter. Before it was 2sc5198/a1941, i replace it with 2sc5200/a1943. It got 2 way passive crossover.

It works, no noise albeit a little muddy. Maybe because i use elna silmic which need some burn in period. And yes, i know it is improper using electrolite as input caps, but i like it. The original caps is generic eletrolite anyway, so it might be an improvement.

The problem is, i got 120mv dc offset on one ch. The other 3 was below 20mv measured. On this ch i use the original final transistor, it was the 2sc5198/a1941. I recheck all the resistor value, nothing wrong. I also resolder all the solder joint. The one thing i notice is 0.01v diffrence between the base of the 2sc5198/a1941.

Did i miss something? Do the 0.01v diffrence between the final transistor pair base is the problem or should i look somewhere?

Here i attach the before and after pic. i add the gain stage later on and is not in the after pic, it was before hf filter on the amplifier input(it was 2.2k resistor with 100pf to ground, the input resistor is 10k):

Hi all,
I have a JBL XE-4 without crossovers bought it from a friend, Id like to rebuild its original crossovers.
Can you help me?

Thanks,

I recently purchased an onkyo m504 and have received some help on connections and for that I am grateful as I cant even obtain a manual. Would anyone know if I can just use standard rca type monster cables for the direct inputs to receiver or is there a special cable designed specifically for this type of setup. Next concern is ,is it acceptable to plug this unit into a joule protection outlet with other units sharing same one? The outlet bar is a good quality piece by monster. Your suggestions appreciated thanks .

Hi,

My thread came back to life, but the title doesn't reflect properly the content. I'd like to edit the tile.

https://www.diyaudio.com/community/threads/tgm8-an-amplifier-based-on-rod-elliot-p3a.245619/

Current Title:

TGM8 - an amplifier based on Rod Elliot P3a​

Proposed New Title:

TGM8 - my best amplifier (incredible bass, clear highs, no fatigue)​

Yet another funny Chip-Amp: The Deviant

Hi there,

I have already described a number of amplifiers based on chips not initially intended for audio, mainly voltage regulators:

http://www.diyaudio.com/forums/chip-amps/176052-now-regulator-chip-jlh-amp.html
http://www.diyaudio.com/forums/chip-amps/192934-se-class-regulator-chip-amp-madness.html
http://www.diyaudio.com/forums/chip...oss-tringlotron-regulator-chip-amplifier.html
http://www.diyaudio.com/forums/chip-amps/193214-class-chip-amp-now-complementary-version.html
http://www.diyaudio.com/forums/chip...ator-chip-amp-family-welcomes-new-member.html
http://www.diyaudio.com/forums/chip-amps/175457-just-fun-regulator-chip-amplifier.html

This time, I set my sights on another category of circuits, vertical deflection chips for CRT TV's.

These circuits contain a number of function blocks, including a power amplifier.
In its normal application, it is rather far off from an audio amplifier, being current output and featuring flyback handling circuitry, but it can very easily be converted to an audio amplifier.

To that end, the flyback generator is left apart, and the PA supply is directly connected to the power supply.
The inverting input is available at pin 10, and is connected to the feedback divider formed by R3 and R4.
The DC output level is set by R5.
There is a compensation cap, C3 connected to an intermediate stage of the amplifier. There is also a 220K resistor, but it does seem to be useful for audio; it probably helps control the circuit during the flyback period, and its only apparent effect is to reduce the loop gain.
The inverting configuration is slightly inconvenient, because of the lowish input impedance, and the fact that the amp goes into unity gain when the source happens to be disconnected.
To avoid instabilities in this scenario, C5 provides an HF path to the ground.
Note that the feedback resistors could be made significantly larger without problem: the typical input bias current is only 100nA.

Now, the $1,000 question: does it actually work?

Yes!!!!, and rather well: it provides a good clean output, is well behaved even with a 10KHz squarewave and has a power bandwidth extending to 25KHz, quite OK for audio.
With a 34V supply, the output power reaches 13W at the onset of clipping.

To cope with this power, I have improved on the original heatsinking method: I have made a U-shape copper heatsink link by bending a power bus strip.
It is soldered to the tabs, very close to the case to minimize the thermal resistance, and the underside is pressed against the bottom of the IC, with thermal compound in-between.
In those conditions, the chip has no problem delivering 13W sinus into 8Ω. It wouldn't be prudent to go lower, as the maximum peak current is already exceeded.

Could other function blocks be reused in an audio context?
The oscillator is probably ruled out, because of the positive feedback.
It would be tempting to use the flyback circuit to boost the supply voltage, like in Philips chips, but bits are missing, and it requires an inductive load to operate.
The internal regulator (pin 7) can be used to supply other circuits, like a preamp or a tone control.
The buffer, between 12 and 1 is probably perfectly usable, I will certainly try it.

One thing to be noted: this circuit does not include a short-circuit protection, and I had the occasion to verify it the hard way: an alligator clip went loose, brushed very shortly on something else, and it was gone.
Funny thing, it didn't go dead short, unlike 99.9% of semiconductors: instead, it went open circuit, something must have played the role of a fuse, either a bonding wire or a metallization.
This means that I didn't have time to carry out more detailed measurements, like THD for example, but anyway, it looked quite decent.

In short, a good little chip-amp requiring very little passive components and working surprisingly well.
Note that the TDA1170 is a very old circuit, modern IC's can certainly do better regarding power, bandwidth, and features like short-circuit or thermal protection

HI. I am interested in finding some pairs of TPX cone drivers (Mid-woofers) from Audax/Polydax. if you happen to have some, let me know what you have and how much you want for them. I am in California. Thanks!

Hello,
I could use help with a preamp circuit I have built. This is a 12AU7 cathode follower buffer into a 3-band tone control from the Max Robinson website: https://www.angelfire.com/electronic/funwithtubes/Amp-Tone-A.html
The output of the tone circuit goes to a John Broskie CCDA line-stage: https://www.tubecad.com/2009/03/blog0161.htm

Functionally everything works, but with the tone control section in the circuit I am getting hum on the output. With the scope probe, the excessive hum appears starting at the plate of the first CCDA triode. There is hum on the grid, but it is very, very, small signal. If I disconnect the output of the 12AX7 on the tone circuit and connect the cathode follower out directly to the CCDA section, no more audible hum. (the green line on the schematic). The signal gain of the circuit remains relatively the same whether the tone section is connected or not.

The power supply is very well filtered. The 12.6VAC heater supply is elevated 48V.
The hum signal on the scope, when spread out to 20usec shows about a 50kHz signal.

Could it just be heater noise? Thank you for any ideas

Anyone has idea which components fails would cause these sound? The popping sound comes and go. I'd replaced the 6 capacitors since I open up and found out some of it was leaking then got them replaced

Hi all,

Is there an elegant simple solution to applying a filter of some kind in a DSP (such as MiniDSP HD 2x4) to adjust phase from a frequency range on a sealed sub so that its easier to integrate with bass reflex subs? I'm trying to flip the phase of a sealed sub in the 10hz to 25hz range (unless it would be easier to flip the frequencies above it, and then just invert it in the DSP). I was reading about all pass filters. And reading about other methods, but they're beyond complex. Surely there's a more simple way as this is not for a full range speaker but just for a very limited range such as with sub frequencies (10hz to 100hz or so total).

I have a Umik-1 USB microphone, MiniDSP HD 2x4 and some basic use of REW at disposal.

Edit: Surely it's not as simple as using RePhase plugin and using the parametric phase sliders to adjust phase -180 degrees in the ranges I want and just generate and import into miniDSP FIR on the channel output?

Very best,

Hi all, first post here and not one I wish to be making! I've owned an A85 since 2002, was in mint condition. In the last 10 years or so it hasn't been used very much for audio. It was paired with a CD72 and used to be the centre piece. More recently it was driving the fronts on a 9.1 atmos set up on a denon x4100w. About 6 months ago the denon blew up whilst just powered up (not driving) so I replaced it with a 9.1 powered Onkyo RZ50, now rendering the a85 kind of homeless...
And here's my point, I agreed to sell it and courier via parcelforce insured who managed to trash it the front panel within 24 hours.... fuming!!
I've refunded the buyer and they have returned the amp to me. I've stripped the front off and already messaged Arcam who no longer stock parts. I feel I can repair the broken parts almost fully, my only issue is 2 components on the front PCB - I've looked at the repair manual and got the following info
The power switch on the PCB doesn't work (SW17, TACT SWITCH BOURNS SDTX-644) and the volume control was broken away from its board attachment (SE18, EC16B2414)
I have managed to power the amp on by shorting the power switch on the PCB and controlling the volume via the remote. It all works fine, so if I can get a replacement for those 2 parts I can at least get another a85 into circulation.
Can anyone help identify replacements please?

I have a truck I inherited from my late brother, and he was big into car audio, having worked in the 1980s as a professional installer for a while. He installed an Alpine CDA-7838 Receiver/CD player in it, but it's got some issues. I do electronics repair work, so I'm just hoping to get pointed in the right direction since I have little experience with these. This is a unit with a removable faceplate. In general, it works fine, but it has some glitches.

Sometimes if I go over a bump, the whole unit will reset, and I'll lose all the radio station and time settings. I've checked the power supply, ground, and plug connections, and they seem to be clean and tight.

The lighting of the control buttons is flaky. Sometimes the buttons are lit. Sometimes they aren't. According to the manual, there are no controls for the lighting, so it seems like they should always be on.

Are there any known issues with Alpine units of this era? I'm thinking cracked solder joints. Should I look first in the main unit, or in the faceplate?

I was recently diving down the "distortion" rabbit hole. I had an idea about getting rid of crossover distortion. But I hit a snag. The idea was to use an all-pass filter and have it be triggered by a ZCD. I was thinking of the all-pass being an elliptical as well (for the steep curve) but I'm not sure I would want all that ripple. I guess I have two questions then:
1) is this feasible in the analog domain?
2) what filter would give me a steep enough curve to be right on top of the zero crossing? For that matter, would I even need such a steep curve?

Good evening everyone

I just bought a Dayton Audio DATS V3. I know there are several previous posts regarding the use of this device. However, I just wanted to share my experience using DATS V3, and hope to get some feedback from people with more experience than me. At arrival, I quickly set up the DATS to run some T/S measurements on a handful of drivers I have laying around. These drivers are:

Scan speak 21W/8555-01 (4 pieces)
Scan speak 21W/8555-00 (2 pieces)
BMS 15S320 (measured only one)
Fostex FF85K (2 pieces)

Some observations:

• I have four 21W/8555-01, which all measures pretty much the same (very high degree of consistency). All four woofers new in boxes. I broke in two them by simply running a low a freq. signal in free air for three days before measuring them. The remaining two came right out of the box (no brake in). All four woofers pretty much measured the same (only some minor differences). For all of them, Fs is very close to factory spec (meas. Fs = 19-20 vs. fact. spec Fs = 19). However, Qts is way off (meas. Qts = 0.37-0.38 vs. fact. spec Qts = 0.26).
• For the two Scan speak 21W/8555-00, observations were similar to the observations for 21W/8555-00. Right out of the box, the two woofers measured the same (meas. Fs = 21 vs. fact. spec Fs = 20) and (meas. Qts = 0.44 vs. fact. spec Qts = 0.31).
• Measurements for the BMS 15S320 was bang on factory specs (meas. Fs = 42 vs. fact. spec Fs = 41) and (meas. Qts = 0.29 vs. fact. spec Qts = 0.28). Also, this woofer came right out of the box.
• Measured specs. for the Fostex drivers were quite different from factory spec. Higher Fs and Qts. I got these drivers from Planet10 some years ago, and they came with measurements performed by Planet10. By comparison, I got slightly lower Fs and Qts, but differences were marginal. That makes me feel somewhat confident that the DATS V3 works as intended.

I intended to make a FAST speaker system using the W21/8555-01, but I got somewhat concerned using the factory specs. I would very much like to hear from someone else with more experience on this topic.

Cheers

Hello

i have a power supply board here (already bought) (https://www.thel-audioworld.de/module/NT-HQ/NT-HQ.htm#NT25) that is able to provide symmetric power and im wondering if i could power a +9V dac with -4V/+4V instead of +9V/GND and if it would bring any potential benefit ?

another thing im wondering since these can act as 2 seperate power supplys ... my dac needs 9V and my headphone amplifier 18V, could i series both sides for 18V and just use one side for 9V at the same time?

(also any comments on the power supply itself are appreciated, is it good? and can it be tweaked further? additional caps?)

Hi folks,

The plan to make yet another cube enclosure with full range speaker. I know it's not the best but please bear with me.

Outside cube will be 18cm3. Internal wall will be 2cm thick with 4-layer perimeter and a 50% infill. Material will be black PLA. Outside will be sanded and painted, I want a piano black finish.

The front face will be made of 1 inch birch plywood.

I plan to use the Mark Audio CHR70.3 but I’m flexible if a better match could be found in the same price range.

Box will be closed back with some fill material, but it could be ported if desirable. I will use the speaker only near field in a small room. Port distortion, scuffle or other noise is a big no-no for me. That’s why I plan to go with closed enclosure and maybe add a subwoofer if I find the bass is lacking.

The big part that I need help is with the internal geometry. Maximum possible internal volume would be a 4L cube. However, since I’m printing it, I could easily make a cylinder, a demi-sphere, rounded corner, etc.

I thought going with the golden ratio, but it would reduce the internal volume to only 1L which is not desirable.

3L internal enclosure is possible with a demi-sphere design or a cylinder design. I’m not sure if losing 1L internal volume for that is desirable.

I could go the rounded corner route, which will have a lesser impact on the internal volume, but I’m not sure if it would help with the resonance or not.

What do you think would be the best to avoid the cube resonance issue?

Should I brace the speaker in such small enclosure ?

Thanks for you help 🙂

Look inspiration: Login to view embedded media PLA 50% review : Login to view embedded media

Had some PCB's made for a preamplifier project. It is the "Precision Preamplifier" by Douglas Self, as described in his book "Small signal audio design". And after finishing this project, I have some boards left. The amp worked great btw, and I've only discovered minor error in the design (swapped "Hi Gain" and HI freq" text in slikscreen and too big lead spacing for two caps, but nothing that really mattered).

So if anyone is interested; I've got 4 pcs which I offer for €4 each + shipping (about €7 for Europe). There's schematic and BOM with Mouser part no's available too.

DM me if you're interesting.

I have a bunch of "cube" shelves. They are 16in wide x 16in high x 12in deep. I'd like to build matching boxes for a set of speakers and subs.

The plan is to have 2 full range speakers, and 2 subs. I think I've settled on 8" all around, but I could do differently if that would sound weird.
I think I'll build them to look like the MasterSounds speakers since they are symmetrical and fit my "design limitation" (the cube shape).

I need help with the internals though. I've looked at a few different layouts/blueprints around but I guess I need a sanity check. Mainly I can't figure out why I would pick 1 layout over another. Like bass reflex, maze, single fold L, 4th order, 6th order, so on. based on MasterSounds they just list the Speakers as Bass reflex, and the subs as 4th order. Should I do the same? CAN I do the same? Do I even need to worry that much? I was thinking just doing it like this for the Speakers. And like this for the subs.