Hey Guys,

This forum has helped me a lot in learning and building speakers. In the past, I did do couple of build using Mark Audio Pluvia 7 drivers as per below build thanks to Dave's design plans.

Bass reflex: https://www.diyaudio.com/community/threads/ma-pluvia-7-bass-reflex-bookshelf-speakers.354125/

And

MLTL: https://www.diyaudio.com/community/threads/fullrange-bipole-mltl-speaker-build.351281/

I did not keep the MLTL for long due to their size. but, I still have the bass reflex speaker and have quite enjoyed them over the time.

I am now looking at building another set of speakers, as the Pluvia 7s don't quite offer much in bass region, leaves me wanting more. In the past, I did use them with subwoofer, but now I am simplifying my setup and don't want to add subwoofer in the mix.

What are my options for a fullrange speaker build that offers bass down to 30-40hz region and still sounds good up top and in midband? Being in Australia, options of getting the speaker drivers are bit limited and importing can be costly. As such, I am keeping my options limited to what is currently available locally from darcher.com.au.

So far, her is the list of the drivers that are locally available.
Mark Audio Alpair 10p: http://www.darcher.com.au/store/index.php?route=product/product&path=59_60&product_id=95
Mark Audio Alpair 11ms: http://www.darcher.com.au/store/index.php?route=product/product&path=59_60&product_id=99
Mark Audio Alpair 12P: http://www.darcher.com.au/store/index.php?route=product/product&path=59_60&product_id=67

Before I go ahead and order couple of drivers, I just wanted to get the recommendation on which drivers to get and which design to build.

Here is what I am looking for.

• Easy to drive (around 90-91db sensitivity)
• Good bottom end (around 30-40hz)
• Somewhat flat frequency range
• Good soundstage and imaging

For now, I am thinking of building Pencil design http://frugal-phile.com/boxlib/pensils/Pensil10p-plan-140613.pdf with Alpair 10p, but I am open to other suggestions both in speaker driver and box design (apart from Furgal horns), but as said above, in Australia its bit limited. Will the bigger drivers be better alternatives?

Has anyone given some thought to the idea of a diyAudio Full Range Reference Project and groupbuy?

My thoughts were:

A modestly priced driver. Say the FE103/107 or FE126/127. The 40-1197 would have been a strong canidate if it was readily available.

The enclosure would be a simple t-line or folded pipe with dimensions that would allow the use of standard boards so that the woodworking was not scarry.

A simple BSC, a well documented webpage and of course rhe friendly and knowledgable in the forum.

This way, several of use could compare speakers to this reference project and discuss.

Anyway, it is just a thought.

Regards,
GM.

Hi all, when designing your drivers how do you calculate the magnetic field strength "out where the membrane is"?

And what are the values you find there? Many thanks.

Hi Hugh and all in the Aksa community.

As the title says.....its been awhile.

A lot has happened since I was last here. Covid! Hugh's sickness, and 4 years a ago after being together for 34 years, my wife died. And at that time most of my audio gear gave up the ghost as well.

So to 2022 and the pursuit of "Audio Perfection"

What I am currently listening to:

Sony BluRay player - hardly ever used
Apple Imac
Roon - all CD's ripped in FLAC
Tidal Master (MQA)
Stack Audio "Link"
SMSL M400 DAC
miniDSP DDRC24 with Dirac Live v1
Yamaha Pro Audio powered set up - ok but..... going

AKSA gear:

GK1 - dead with Phone stage, Siemens gold pin 7803, still good
Paris Step up, new, never used
First addition 55w still working but time for an upgrade
GK1 Board - unpopulated
55N kit, new, never installed

Old gear laying around:

Musical Fidelity "Synthesis" 80's 70w still working
FX Audio 802C Class D New 6yo, baught for a project that never happened.
Lenco Turntable parts to build a PTP Lenco "One Day", no arm, Denon DL103R

Next step:

Duevel Venus Speakers arriving in about 3 weeks. 4ohm 88dB. I think they dip to 3.7 ohm in the lower frequencies.
I will use all 3 amps to see how they sound with and without the DDRC24 but I need a new AKSA
But, Maya 200 or the new 125?
As these are here I will try the pair of Yamaha DXS12mkii (Band Pass enclosures) below 50hZ to see how they integrate, it may work but not expecting much.

So, please thoughts and suggestions.

And my New Year Resolutions: let's hope Covid ends soon. No war between Russia and ? everyone! , and no war between Egypt and Ethiopia over the damming of the Blue Nile, look this one up, it's not looking good! The Nile could end up like the Aral Sea.

Mark

Does anyone have the schematic for the old CSS kit 41 crossover? I have a pair each of the WR and FR 125 drivers lying around and lost any information on them. Ultimately didn’t leave these in my system but these should be okay for surround and height speakers.
Thanks!

Does anybody know if these speaker connectors are available anyplace? One of mine busted. 😡
It's just the plastic wing nut so pliers work but I hate knowing that it's busted. I've done some searching but no luck. I'll also try ML. Their current line seems to very similar but that seems to good to be true. Thanks in advance and cheers,



It

Good afternoon,

Last year I designed and built a 3-way active crossover network, using circuits pulled directly from the Linkwitz Lab site. The crossover was intended to replace a MiniDSP 2x4 and add outputs for subwoofers. It went together just fine and sounded pretty good, albeit a little warm. Fast forward to a few weeks ago, I was playing with a newly acquired Umik-1 and noticed that there was a definite high-frequency rolloff which is dependent on the position of the potentiometer used for volume control. Below are two traces, one with the pot at 50%, and one at 100%, with the source output level adjusted to give the same volume on the low end. Note that these were taken in my living room on a makeshift mic stand, so they aren't particularly pretty, but they do get the point across.



My first instinct was that this was due to the lack of a buffer between the volume pot and the high pass filter for the tweeter, as shown below. However, the rolloff seems to start well below the crossover point (1,250 Hz), with the levels already down ~2 dB at 700 Hz.


Above: Input HPF / buffer and volume pot (left), high pass which takes signal directly from the volume pot (right)

My attempt to solve this would be to add an additional buffer between the volume control and the filter stages, so there is no interaction between the pot and the other passive components involved. Can anyone guess as to whether this might solve the issue?

Additionally, if I am going to layout the board again, I wanted some input on the ordering of the filter stages. Linkwitz hints that the order is important on his page, but doesn't offer any advice as to the optimal layout. Here is the how they are currently arranged:



My main question is regarding the shelving low pass for the woofer baffle step compensation, since it is the only stage with a non-unity gain; should it be at the beginning of the woofer filter chain, as shown above, or at the end?

Finally, I wanted some general advice with the PCB layout. I'm not currently experiencing any issues with RF or weird noises, but I'm sure my layout could be improved. The only considerations I had in mind with the design were to put a small filter cap on the V+/V- pins of the opamps, and to try to keep power traces away from signal traces when possible. Here is the layout of the board I went with:




Are there any blatant issues that stick out in the above layout?

As always, thank you for reading and I appreciate any input that y'all might have.

Kellis

I’m currently in the process of brainstorming ideas to mod one of these:



Into one of these:



Using 2 of these (one at each end):



I haven’t got the pipes yet, so can’t calculate the space it would give, but a very rough estimate is about 5L with an internal diameter of about 100mm.

I was wondering if someone here would be able to calculate the required space for the following drivers:

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I’m also open to any suggestions for drivers.

Pyle Audio PP999 Ultra Low Noise Phono preamp. Hot Rod mods include upgrade power supply filter caps from cheap 47uF to Panasonic FC 220uf, (one per each voltage rail) removed cheap electrolytic input caps and replaced with Tantalum caps, removed cheap electrolytic output caps and replaced with 2uF Panasonic poly film/foil. Added IC socket so you can replace stock NE5532 with your choice high end audio opamp (both the LM4562 or the OPA2134 sound fantastic in this circuit). Even without the opamp swap, this sounds way better than it should with the mods...even better with opamp swap. 100% operational, no hum, no noise. This easily competes with preamps 2 to 3 times my asking price.
Original AC wall wart, box and packaging. Asking $75.00 obo

Shipping CONUS only.

Does anyone have any opinions on the viability of mating Magnepan DWM bass panels to Apogee Stages? I’m aware of the limitations of the DWM panels in terms of only going down to 40hz. Combining them with the stages would be similar to mating them with small to mid size Magneplanars. The compounding of the two speakers’ abilities to go to 40hz supposedly gives the illusion of deeper bass. Does this theory have merit or did I drink too much champagne over New Years and it clouded my ability to think rationally?

Hi all. I'm not going to settle the component quality argument for everyone, but I'm going to settle it for myself. I have a set of Partsexpress bookshelf Tritrix MTM speakers I built from the kit. They sound pretty good and are easy on the ears but lack detail. My understanding is difference with quality crossover components is improved detail; Perfect for a test! I'm going to upgrade the crossover capacitors and resistor of one of my MTMs and do a listening comparison. I limited the budget to $100 for both speakers (give or take) so I am putting in one step better than stock main capacitors and coupling them with a high quality small value bypass caps. I've heard the sound will take on the characteristics of the smaller cap. I wanted to use Myflex KPCU bypass caps but that blew up the budget so I looked at the Jantzen Superior-Z caps which have great reviews and kept me at $100. The problem was I really wanted to try some copper foil caps so I compromised and am using Myflex caps on the tweeter and Superior-Zs on the woofer- total cost of upgrade is $115.

The crossover schematic is attached. Here are the upgrades:
Current Components (replacement components)

Tweeter
10mf Dayton DMPC cap (10mf Jantzen Standard-Z + .22mf Myflex KPCU cap)
2.4 Ohm 10w Sand cast resistor (2.2 ohm 12 w Mills wire resistor)

Woofer
20mf Dayton DMPC cap (2x- 10mf Jantzen Standard-Z + .22mf Jantzen Superior-Z cap)

I'll post some pics of the before and after and then I'll provide an honest recounting of my perception of one speaker with the upgrades and one without.

Thanks for reading.

Bill

I would like to repurpose this small 6BQ5 SE amp out of an old record player. I do not care to use it for phono, plan to hook a BT receiver to it and go. I have no "Grand Illusion" as to the fidelity, tone stack or volume controls are not required. I will recap it and check resistor values that they haven't drifted. The purpose for it for a small office.

1. Bypassing the tone stack - I have tried it using just the second gain stage and it wasn't enough to drive the power tube. Conversely cascading the 2 halves of the of the 12AX7 was way too much gain, 12AV7 sounded about right.
Recommendations on bypassing the TS and volume control? BTW the controls are on a long umbilical.

Any recommendations are appreciated.

BL

Hello Everyone,

Hope you are all well.

I am looking for a preamplifier circuit / kit made with depletion MOSFETs which are connected in SRPP circuit, that I can use to build a 300B or KT-150 amplifier.

Thank you,

Bertrand

This just hit me. I knew of their existence. I just never cared about them. I don't really care about them now, either. But I thought it could be fun to ask. I googled and searched here for "7-pin." I didn't come up with any relevant hits. (From Google I learned that lots of dealers carry 7-pin sockets.) I'm sure this has been here. But since I don't know which, if any, 7-pin tubes are popular, or even used, I don't know what to search for.

I looked into these tiny tubes and they seem to have specs similar to those of "space-age" novals. They look pretty impressive. Some are designed for VHF, some for audio. They also have relatively low maximum voltage rating. I don't know if the latter is good or bad.

Anyway, has anyone here had any experience with these?

Cadence M4000 class D full range 4-channel Korean amplifier:

Problem: When powered up, no load, amplifier in protect mode. Every 4 seconds amp attempts to power up automatically then immediately goes back in protect mode.

What I have found:
Through checking with multimeter, Channel 1 output fets (19n20 and 17P10) shorted. One trace burnt (between D118 and C169 in picture).

What I have done:
Removed rectifiers, powered up via variable voltage low amperage P.S. and the power supply section looks fine. square wave (+14v on power supply fets) and + 30v/ -30v on rectifier pins. All fets cool, idling fine with power led on and no protect mode.

Fixed the trace by soldering in solid copper jumper wire. Pulled diode D118 and it checked good also checked C169 and it was the same as all other capacitors of the same value. All other resistors seem to be within tolerance.

Should I be able to replace the two shorted output fets and test it or should I test the output driver board? If there is a bad component on the driver board could it cause a failure of the output FETs?

Which brings me to my questions about the driver board.

The numbers on the ICs have been removed. The one IC that is a 28 pin, I can not find anything like it, other than the y-tech IC in the tutorial, but that is not really like it either. Does anyone have an idea what the number could possibly be? It seems like one side (14 pins) pertain to channel 1 and the opposite side pertains to 2 when following the traces. The same with channels 3 and 4 on the other end of the board.

Also any idea of the 14 pin IC next to it?

The 8 pin dual comparator is a A393F.

Also there are two types of driver transistors I am assuming P and N that are labeled under "Qn.." {n=1 to 4}, "ZH C0" (only thing I can find with that nomenclature is a HSMS-2820 Schottky diode, but I don't think that is correct) and "ZG C8" (maybe BCF30 PNP transistor?) and another labeled "Dn.." {n=1 to 4}, "F3 J8" (maybe a BCX71JR, BJT transistor connected as a diode?)

Also does anyone have a schematic that would be close to this "Asian clone" amp.

The amp uses:
IRFZ-46N PS FETs
FQP17P10 and FQP19N20 output FETs
KIA7806A and KIA7906PI +/- 6V voltage regulators
KIA7815A and KIA7915PI +/- 15V voltage regulators
FMG22R and FMG22S rectifiers

Lastly is Newark a good place to buy the 17P10 and 19N20 FETs from? Digi-key and Mouser are out of stock on the 17P10.

Thank you in advance.

I have Vox AD60 VT with burned output transistors, without labels. Please, my question, what kind they are?

i want to build a 6-way system where the top 3 frequency bands are horns

although i could just go with off the shelf horns i'm toying with the idea of making the horns myself

for the smaller horn i am thinking about 3D printing the entire thing in one piece ...

for the bigger midrange horn i'm thinking about 3D printing just the throat and making the mouth out of flat Plywood pieces, so it will be somewhat square looking but should not affect performance that much compared to a perfectly curvilinear horn ...

i don't have a 3D printer and would have to use a 3D printing service of some kind ...

anybody do this ? any tips ? what sort of material to use for 3D printing ? what kind of software to use to design the 3D printed part ? what software to use to design the plywood part ?

are there any sort of known issues with 3D printing horns ? i have never 3D printed anything.

i have a good understanding of acoustics i don't need help with design of the horn itself just in translating my vision into physical reality ...

i have access to SolidWorks software but i am not married to it ...

thanks in advance for any help.

i want to make a lightweight plywood 3D horn like this:

Login to view embedded media
he's using SolidWorks which i actually have access to, but is this really the best way to go ?

his model has some kind of weirdness where the plywood meets - will solidworks calculate all the angles i need for everything to fit perfectly ?

i basically want to use this type of construction for about 80% of the horn and 3D print the throat. there is some kind of 3D printing and prototyping shop 10 minutes away from me literally in some guy's home and the pics he has on google maps show pretty big parts but not quite as big as a 30" wide by 30" tall horn mouth.

aside from the horn basically the entire speaker would be all weird angles - basically think JBL VTX array type cabinets where most of the angles are odd. no way i can ever make it work without the computer doing all the math.

also will i need a separate software to design the 3D printed part ? i think it would if i could design both the plywood and 3D printed parts in the same software as they will need to interface with each other, plus i wouldn't have to learn two pieces of software but it's not a deal breaker if i have to use different software for plywood and 3D printed parts.

i feel like it's time to move from hand sketches to 3D cad models to see how everything really fits, or if it fits.

i have a thread on here about designing a system that flip flops between 5 and 6 way and one of the questions i struggle with every day for the past couple weeks, maybe months is how much of the budget is reasonable to allocate to a particular frequency band ...

so i been doing some googling and i think maybe we can have a thread where we can pile on all the various bits of information we have that can help people get an idea of relative importance of various frequencies to overall experience of listening ...

here is something i just found a few minutes ago for example:

https://www.dpamicrophones.com/mic-university/facts-about-speech-intelligibility
specifically this chart:

https://cdn.dpamicrophones.com/media/images/mic-university/facts-about-speech-fig04_1.jpg
it shows relative importance of various frequencies for speech intelligibility ... now you may ask who cares ? we listen to music ! well ... because there is a good reason to suspect that our brain has evolved to process certain frequencies more efficiently BECAUSE of language ... in fact our brains have pretty insane performance in terms of being able to pick out what somebody is saying in a room with 20 other people talking ... it probably makes sense to match the resolution of your sound system to the resolution of your ear-brain mechanism in terms of which frequencies are handled most clearly ...

and here is something i found a few days ago:

https://www.axiomaudio.com/blog/dis...ortion at levels,the masking effect of music.
specifically this chart:

https://www.axiomaudio.com/pub/media/wysiwyg/distortion_figure02.gif
it shows how loud distortion needs to be for people to hear it versus frequency ... not surprisingly it closely mirrors the speech intelligibility curves with stuff below 120 hz being essentially irrelevant with distortion up to almost 100% being almost inaudible at lowest frequencies ... and then as frequencies increase so does our ability to hear distortion ... but unlike with speech intelligibility there doesn't seem to be any corner at 3 khz and the trend simply continues ...

probably because of this ( from the same DPA blog )

https://cdn.dpamicrophones.com/media/images/mic-university/facts-about-speech-fig03.jpg
namely speech begins to roll off around 3 khz about the same area where ears are most sensitive

so our ears, brain and speech have all evolved in parallel around the same frequencies ... ( no surprise there ! )

our ability to detect distortion is basically zero at 20 hz and rises steadily all the way up to the very high frequencies ...

and our speech spectrum is from about 200 hz to about 5 khz with a peak around 1.5 khz or so ...

speech intelligibility is simply a product of the two curves - the frequencies where we can detect distortion AND where speech audio has high energy are the ones most critical to speech intelligibility ...

going to conclude by attaching a chart a member of another forum made where he analyzed his own music collection using REW ... this information is consistent with my own measurements and with what i have recently read in an AES paper on hearing damage from loud music ...

when you put all these curves together you begin to better understand where to allocate budget in the system to achieve the best results ...

i hope others can contribute their insight as well ...

EDIT: here is the AES paper on hearing damage from music that i'm reading:

https://www.aes.org/technical/documents/AESTD1007_1_20_05.pdf
among other things they ask questions like why do people like loud music and why do people like loud bass ...

I just purchased a set of Fluance Ai41 powered bookshelf speakers and when I ran my Rolls Bellari PA550 headphone / preamp from my turntable to the speakers 90w class D amplifier and played a record it began to clip horribly. After reducing the preamp volume, I soon found that I have an issue with the volume of the Fluance suddenly dropping down during parts of certain songs with more abundant bass and high frequencies. This problem persisted after further lowering the volume of the external preamp. Eventually I disconnected the Rolls and switched to the turntable's internal preamp and this eliminated both problems. But now, although I am pleased with the sound of the Fluance speakers, I would still prefer to have a preamp attached to the system that will not impact the speakers in this manner. What is concerning to me is that at least two of the reviews on the Fluance site mentioned this very same issue with their very own PA110 preamp running into both the Ai41's and the Ai61's. If this issue exists with their own preamp, is there really ANY preamp that will not activate what is obviously a feature meant to protect these speakers?

Hello you audio enthusiasts and geniuses you! I need you help. I've been wanting to do something with these q100 drivers for quite sometime. Tried wide disperson speakers, narrow, sealed, ported, full range open baffle, and I think the design that has won my heart is open baffle. Have yet to hear multiple driver open baffle, but I think that's the ticket.

I would love to build an open baffle speaker using 2 GRS 15" drivers in parallel along with this q100 driver. I'm ok experimenting but the largest purchase (besides the drivers) will be the inductor. Is this a value that you can take a stab in the dark and work the rest of the crossover from there, or do I really need to nail that value?

Decent amount of info on the speaker/driver here
https://www.erinsaudiocorner.com/driveunits/kef-q100-drive-unit/
and here
https://www.audiosciencereview.com/forum/index.php?threads/kef-q100-speaker-review.11987/
Do I start by just plopping all the drivers in the baffle and measure and decide what the values should be after measuring?
For instance it looks like the q100 woofer has sensitivity of 87db not sure about the tweeter but I would start by using the stock xo so I would assume the same sensitivity with the xo. The GRS 15" has a sensitivity of 87dB 2.83V/1m, Can I makeup the 6db baffle step by adding the second woofer in parallel. My lack of knowledge is probably starting to show itself 🙂

Would the spacing be too far apart to have the Woofers stacked if I crossed at 400hz or so? (Don't even know how you create an analog XO to crossover at specific frequency or at what slope. I saw some suggesting a 16guage 14mH Inductor for the woofers. Does that make sense?

I wan to get started and not sure where best to start without throwing money away.

One other thought was using my 2x4HD mini DSP and bi amping to keep the q100 analog stock XO and using the MiniDSP to blend the woofers with separate amplification.

I have Umik and REW for measurements and know enough to know I don't totally know what I'm doing.

I am selling a corner dipole subwoofer that is based off of plans from the November 2004 issue of Audioxpress magazine.

It features two Acoustic Elegance IB15HT drivers.

It is a unique beast it gives up max spl for a quick decay of bass in the room.

An active eq is a must. I can include my minidsp if the price is right.

It is heavy so I imagine this would be local pick up only in Minneapolis, MN USA

It is made from 3/4" baltic birch with tropical tigerwood bracing.

More info and pictures here: http://projectgallery.parts-express.com/speaker-projects/corner-dipole-subwoofer/


$400

Just recieved this unit that isnt working.
Just says 'not working' on it
Anyway plugged it in and it started to smoke-rectifier melted and the left cap is very swollen.

Not really a problem but different than before, when I type something stupid in the reply box (happens more than I’d like!) and want to remove by hitting the x (above return) it starts out fast but after 15 or so characters it slows to a crawl……used to start slow and then go faster which worked much better.
Everything else working great, and my 2 cent on the like feature is to keep it……makes for easy agreement without having to reply, especially handy for when things start veering off topic.

edit; using iOS/iPad

I've been tinkering and repairing audio components for a few years as a hobby. I've built a couple of Dynaco Pas preamps, restored a number of turntables and tape decks and have recapped a couple of integrated amplifiers. Some of them done with the help of the generous members here at diyaudio.

I would like to step up my game a bit so that I can understand more of what I'm doing. I've tried reading electronics books but it's such a vast subject that I easily get lost. I'm no stranger to mathematics and engineering but I would like to focus my studying on the essentials that any descent technician (not engineer) should know and would use regularly.

I hope this makes sense, if not then maybe I just keep plugging away and learn as I go.

I'm going to be making 3-way floor-standing and also 2-way stand-mounted speakers, for use with music (not usually movies). To help sanity-check my goals for these I've been looking at the specs (and where possible measurements) of commercial examples by popular hi-fi brands such as Warfedale etc. Most don't go as low in frequency as I'd expected and also roll off much more steeply - often only several Hz between -3dB and -6dB. For example, many (most?) floorstanders I looked at have -3dB and -6dB in the region of 45hz and 40hz respectively, whilst bookshelf types are of course somewhat higher - maybe 55hz and 50hz, or even 65hz and 60hz in some cases - yet still get good reviews.

I had been planning to shoot for somewhat lower (say 35hz) and certainly 'much' shallower roll-offs with a Q of around 0.7 (though it is going to be an active system so could be DSP'd to almost anything, within reason). But that would be at the significant expense of some SPL, and almost certainly more complication from room resonances and annoyance of neighbors etc. So, going by the above commercial examples, this may possibly not be a worthwhile trade-off to make.

So, ideals aside, I was wondering what people on here would classify as a sensible/acceptable/reasonable/normal target for roll-off rate and frequency - for DIY 2-ways and 3-ways?

Thanks,
Kev

Hello.

I have heard a lot off Doxa amplifiers, and their wonderfull soundstage that they handle.

I´am then asking if someone got the schematic?
If wanted, we could trade it for some schematics that I have.

Best regards

Kim

Good day all,

While there is a nice discussion about the Muses electronic volume control designed by our friend @meldano here, I am going to take the opportunity to document my build here for anyone considering doing the same. I wouldn't expect it to be a @6L6 quality build guide, but will follow my adventures while building this quality project.

Muses Volume

I'll be honest, I've grown lazy and find that devices without remote controls aren't as favorable as those with. So I went on a journey to discover VCs that supported remote controls. I found a few really nice ones, some less so. And then my friend @dBel84 suggested I take a look at the above Muses-based electronic attenuator project. Programmable features, input switching, remote control learning... I was hooked. So I reached out to @meldano and was able to secure a board set. After placing a parts order, I was ready to begin.

Since this is my first adventure with SMD devices, I practiced on an old circuit board with some leftover parts from other projects provided by a friend after watching hours of YouTube videos on the subject. Turns out it's not so hard.

So I am starting with the Main Board (input switching, power supply) to get good at wide-pitched devices first. Between both boards I used a combination of soldering iron and hot air rework machine. Soldering iron is much faster if you have the right size and types of tips to work with. But the soldering paste and hot air are fun to watch do their magic, even if you're waiting several minutes for things to come to temperature.

Thanks to @dBel84 for the suggestion to start with the larger components first. The rationale, which is a little different from conventional thought, is that larger parts require more heat to apply (if using hot air) and you're more likely to blow small parts off of their spots with the excess heat needed for larger ones. So I started with the larger LED driver chips and the power regulators.

Next step is to start placing the smaller SMD resistors and capacitors before moving to through-hole components.

Disclaimer: While I know what the device does, I'm not intimately familiar with how it does it outside of the high-quality documentation that @meldano provides in the above-linked post. I'm just following the directions and shooting for a working device when it's done. 🙂

I may deviate from the normal a little bit during this project. The preamp I have chosen to put this VC into uses the attenuator after the gain stage, and this one was designed to go before the gain stage. The input switching circuits feed into the attenuator stage, and then the output is meant to feed whatever gain stage you have. So I will be deviating from the plans a little bit to separate the components in a way that will allow it to work that way.

Typical:
Kit Input Switching > Kit Muses Attenuator >Preamp Gain Stage

My configuration:
Kit Input Switching > Preamp Gain Stage > Kit Muses Attenuator

I've figured how to do this without too much issue, but for purposes of this discussion I'm just going to build it so you can see how it goes together.

Enjoy!
~Chris

Over on the monster Unity horn thread, nc535 wrote:

Suitable midrange cone, for bandpass mid in Unity horn.

"Many successful synergies have been designed in willful breaking of the {~529 = 2*Fs/Qes} rule. The best examples are Art Welter's SynTripp and Chris's MEHing of the Klipsh K-402 with 15" woofers. There is also my own corner horns that use Faital 4FE35's. Of course none of these could be installed in Patrick's car or even a large SUV

If you check the derivation of that rule you find that it applies to exponential horn and says something about the mass roll off corner and the strength of the motor. On a conical horn you have high frequency corners due to the constant directivity and due to the bandpass nature of the mid chambers but mass roll off is not something you need to worry about. Simulate the mids in HR and if HR says they will have the bandwidth you need, then they will. Make sure you accurately model the air trapped under the cone when you do the simulation, though.

If you pick a driver according to 2Fs/Qes rule you will get one that works but it will lack low end and you will end up with a 3-way synergy. Ignore it and you can find drivers that work well and cover the range in 2 ways but you may also need to pay a little more for a CD that can handle a ~1 Khz XO.

Want a 4" driver with a strong motor? Try the B&C 4NDF34!. BL is 9T, more than twice the Faital 4FE35 and it can take more power..."

That got me thinking about two-way Unity horns.

For the most part, I've always made these ultra-small Unity horns for the car, and I've 'handed off' to an array of midbasses. But a two-way would be very attractive if I could actually make it work.

Hello,

I want to make a large 3 way using professional drivers.
These speakers will be used for home audio and will be powered by a Class D Iraudamp DIY amplifier ( made by a friend).

Midbas from 55hz to 400hz range i will be using B&C 15NDL88
B&C Speakers

For mid from 400hz to 2000hz i will be using B&C 8PE21
B&C Speakers

And from 2000-18 000hz i will be using B&C DE250+ B&C ME20
B&C Speakers
B&C Speakers

The enclosure is about 85 liters tuned to 45 hz.

I know that DE250 is a verry good driver but i never saw any measurements with ME20 horn. Has anyone used this configuration?
The same for 8PE21, i didn't find any reviews about this driver and o chose it for it's hi spl and liniar response.

If you have any recommendations or advice on the drivers i am here to listen.

Best regards.
Mihai

In 2015 and 2017 the RMAF hosted and then published on YouTube two interesting discussions about Hi-Fi on a budget : "$500 is a lot of money to some people" , copied below.

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Apart from the obvious costs of a Hi-Fi project, issues of aesthetics, placement, life cycle costs seem to be seldom discussed. Non - technical issues tend to dominate here : acceptance factor, listening levels etc.

As the question, comparing back and white cone versions
Qts for white cone is 0.24, more like a dedicated midrange driver.
Why a difference and also why are specs and measured response of black version slightly different to a year ago?

Sorry for the delay, but I decided to build my own test jig to get a better picture of the noise spectrum.


There are two plots here. I had to go to a double shielded enclosure with the outside shield connected back to signal ground on my A/D. There was still some slight mains hum depending on where I put the box on my bench (out in the middle of the room was best). In any case it was reduced to 2nV or so. I tracked it down to the input cap. I thought I connected the outside foil to ground, but it seems the end termination and FET lead is enough. Next rev will have extra care here. The 997Hz tone is a mystery. I thought it might be the cal oscillator on my scope but it wasn’t.
The noise is plotted on a log scale with -87.2 dB = 1nV/rt-Hz. This was established by taking the best FET and adding a reference resistor in the gate, a Vishay 10k .001% oil immersed precision resistor. I then scaled the plot down to 1nV. This theoretically even corrects the measurements for temperature but this is not necessary under normal lab conditions. I like this better than inserting a tone especially when using FFT’s, everything is scaled without the tedium of keeping track of bin equivalent noise BW.
All the FET’s were measured at 1.2mA Id. The lowest plot is my reference line. It varies just a little and I took an estimate around 1kHz of -87.2 dB. The next two plots (moving up) are a 2SK372 (Idss = 24.19mA) and 2SK369 (Idss = 14.75) respectively. Note the scale, we are only looking at .5nV – 3nV or so. The last plot is a random 2SK170. This is a very nice example of GR noise that would not show up well on a Quantech since it is only 3nV at 10Hz. These noise levels should scale as the fourth root of Id (one of the things that I want to do eventually).
The second plot is all three FET’s with Rg = 10k. It looks like the slight rise at the low end on the 2SK170 is due to the GR noise. The roll off at the high end is probably the A/D. The unexpected result is that the other two plots rise at the high end. This could be induced gate noise but probably not impact ionization since we are at low Vgs. The lack of this in the 2SK170 and the fact that the 2SK372 is in a very small package leads me to believe this is a new/different process, this defiantly needs more study. For now these two FET’s look great for MC for sure.

The last plot is the BF862, pretty impressive for an RF FET!

Welcome the fails file!

Have you ever engaged yourself into a project of nonsense or of no success? And by the time of awareness about the failure - have you then been able to giggle in an amused mood about your own maledicted misfortune, about your betrayed builders brillance or even about your nauseated narcissism? And then, despite the misadventurous outcome, having learned something along this adventure? Yes? Really? Fine! Then share your giggle, your frustration, your suffering or mourning with others. Just share it, not expecting any salvation in doing so, but for the sheer sake of sharing. Or maybe also joint joy. Nothing else.

So this might be the thread for all kinds of these otherwise silently littered projects which for any reason were not successful or were not meant to be successful. Regardless, wheter these builds were fatally flawed, hilarously hopeless, ingeniously idiotic, seriously silly, tragically trashed or otherwise wery wrong … Dont litter them silently, it would be a pity. This might be the place instead where to publish, and then wait and see ... Let others comment and then eveventually lets grin together. This thread is meant to be less serious than recreative and hopefully funny.

I already published such a project which was mainly hilarious and highly prone to fail in another thread (the teggstreme/epoxy midrange dome driver). And here, let me begin with another project of this kind: I was nearly certain that this new, eery iteration would be seriously flawed. But instead of being reasonably renouncing, I just wanted do know what would really happen and built it. Who knows.

So may I proudly present the rubber foam elasticity controlled electrostatic sandwich-folded curtain tweeter: An electrostatically loaded membrane is folded around self-adhesive foam tape. The folds are moved by electrostatic forces from integrated stators, such in a standard ESL. Think of an AMT instead. But unlike in an AMT, the sound should not be emanated by the squeezing and relaxations of the folds distances, thus moving the trapped air, but simply by altering the geometry of the folds free curved surfaces:









I knew, that if it was functional at all, then I would rather have constructed a silentspeaker than a loudspeaker. And as expected, the result was at least a partial mess: There was indeed some sound emanated by this construction. But the sound coming from the transformers was a hefty bit louder instead. And while bilding/folding the sandwich, these free membrane surfaces adhered to the sticky isolation foam tape. So I had to introduce knitting needles to free them again. As you see, one of the plies did not like that.

Lesson learned. Too much resistance, and not enough electrostatic forces.

… And now … Whats your comments, or even better, whats your own story of failed creations?

Hi All

So after a great deal of thought and advice i decided it's time to build this wonderful Amplifier.

This will be my first build and i will be learning as i go along, i am hoping many of you on here will be able to help and guide me.

I have read most of the threads on different websites to get me started, but as you can imagine i still have some queries especially with concerns for the power supply and output transistors.


I've ordered this kit from Jims Audio:

Hiraga super 30W class A w/ current source + kubota reg partial assembled kit ! | eBay

This one being with the Kubota regulator.




These are my heatsinks from a military plane cockpit console.









I realise i need more and i will be machining some add on designed heatsinks to these, i will be also be making and designing my own custom enclosure.


Where i am stuck now is the output transistors and the PSU.


to be on the safe side i ordered these from Jims Audio to just test them.

On Semi MJL4281A MJL4302A matched quad 2%

https://www.onsemi.com/pub/Collateral/MJL4281A-D.PDF

Whats other builders experience on output transistors? Any suggestions?

So far my research has shown these to be popular.

1. Exicon 10N20 10P20 Audio Mosfet TO3P TO247 ECX10P20R ECX10N20R

EXICON - Lateral MOSFET | Profusion


2. Sanken 2SA922/2SA1216

https://www.digikey.com/product-detail/en/sanken/2SA1216/2SA1216-ND/3661801


3. Sanken 2sc3264/2sa1295

2SC3264 ALLEGRO SANKEN, Bipolar (BJT) Single Transistor, NPN, 230 V, 60 MHz, 200 W, 17 A, 50 hFE | Farnell element14


4. MJL0281/MJL3281


Interested if people have used any of these and the results they got.


Now here is where i have a dilemma, its the power supply. I don't even know where to start.


Whats the thoughts on SMPS? is it possible? Anyone here done it with a class A? Would it work?

I've seen so many different designs: Please see pics below.










Check this video out

https://www.youtube.com/watch?v=2OYE7zFONtU

i mean look those bank of capacitors?


Lets start with the Transformer, i can either use Torodial or EI.
I was thinking two separate transformers 400va each rail voltage of 24-0-24?
Thoughts on this?

Then i thought i could use a power rectifier board: one for each channel

Douk Audio 6*10000UF/50V Hi-Fi Amplifier Power Supply Board with Speaker Protect | eBay

Power rectifier board 6x NOVER Auido 10000uf 50V power supply PSU for amplifier | eBay


Would i still need some hefty capacitors before these?


im guessing i need a soft start delay aswell?


Class A Power Amplifier Soft Start Delay Temperature Protection Board 220V 30A


Or would i just go traditional PSU? A hefty transformer 1.2f capacitors and some heavy duty rectifiers?


I don't want to suffer from noise or interference, i do want the amplifier to sound sweet with good mids and bass.

Thats the only thing confusing me at the moment, is what Power supply should be.

So any advice you may have please throw it my way!

Hello all! 🙂

I recently found a Vestax CDX12 DJ mixer cd and i was thinking to transform it to a more "audiophile" project...

The CDX12 has 2 cd players of Philips CDM12.3BL (photo)
Probably it's a cheap mechanism usually used to mobile players..

Under the mechanism seats the main pcb with all the necessary.. (photo)

It got the DAC of Burr Brown PCM1710U.

Can't find the service manual or schematic of the player anyway but i was thinking to transform it to a single cd player with tube output after the dac and if i can to get also i BNC digital output also..

Any ideas? I'm not sure if it's worth but it could be a nice try for me..


Thanks a lot!

Hi all
Mostly DIY peop is Curius of nature.
So I thought i would give a little back and share my unpack and other stuff.
So here we go:
new ESS amt unpack - Album on Imgur

This is planned to end up with the Pass INT-150 driving the Old ESS and some Accuphase Driving the New ESS stuff when that is finished.
But still need some active woofers, cabinet, and off cause to build a crossover to fit the new ESS.
Btw the old ESS is with Anilco magnets and silver wiring internally/externally so it will be exiting to hear the new ESS with Ceramic magnets when I can place them side by side and listen to them and compare using a switch and the Pass INT-150.

Hope you have been entertained

NAD312 Problem SOLVED

I've modified this thread now that i've found out what's the problem with my NAD. I hope this help others.
i've just bought a Nad 312 with the objective of repairing it.
The problem that was discribed to me was that 'the green light powers up but there's no sound'.
The 4Amp fuses that protect the unregulated part of the power supply were blown. I've found 630mA fuses there and i wonder who put his hands on the amp before me....
I've replaced the fuses and powered the amp. the fuses were ok but i fount around -30V DC on both exits of the amp. After some investigations i've checked that the power supply voltages were all ok.
Checked that the pre section of the amp was working fine also. The problem is with the power section.
Checked that no capacitors were shorted and the joints were all ok.
The voltages on the driver and output transistors were completely crazy with -28v on the bases of the transistors. So what seems to be the problem?
Well NAD (and other manufacturers) use some special resistors in key-parts of their amps. These resistors are recognizable by theys blue-greyish color. These are called fusible resistors and they act as regular resistors but when the current through them is too intense they eat up and eventualy blow. They're covered in a special paint that's non flamable so that this won't cause problems.
That's what happens when the amps are driven too hard or when a power surge happens.
In my amp a resistor of 68ohm was open in the positive supply part. Without that to compensate the negative part of the simmetrical power supply the negative took over the power amp ence the negative output.
Some NAD amps are very prone to this because the fusible resistors were not mounted elevated in the board but close to it so they don't dissipate the eat and eventualy they burn up after some time. If your amp stops working check them out before buying new transistors for your amp.

ADVICE: Never change the fusible resistors with regular ones. they're there to protect the amp and if something goes wrong regular resistors may catch fire instead of breaking the circuit!!!!

Hello, newb here so skip if that will annoy you.

I'm planning on using 2x Alpair 11MS in conjunction with a woofer to assist with the lows. Right now I've got some preliminary ideas, but before I go further, I wanted to ask about the crossover. The 11MS drivers will be sealed, with an F6 of 71.3hz. Am I correct in thinking that if I allow them to rolloff naturally, and build a 1st order low pass crossover at 70hz for the woofer, this will be ok? I can't tell if I should crossover lower because

Also I'm a little stuck with matching the drivers to a woofer. If I go in series with the pair of 11MS, and end up with a USPL of 88.1/2.83, against a woofer with a USPL of 87.9/2.83, that should be ok right? I read that generally you aim for 3db higher in your mid/high than the woofer, because of crossover loss, but that won't apply here, right? I understand there's more to matching than that, and I'm still trying to absorb all of it.

My next question is about that, impendence. The woofer I'm eyeing has a F3 of 49hz, F6 of 32hz, F10 of 23hz. That's about as good as I can hope for, right, without going for a separate sub? I am hoping to go with 2 floorstanders. Space isn't an issue for them, but would be for a 3rd box. For the impendence, the woofer is basically all over the place, and I need to just read more on that. Both are nominal 8ohms.

These may be totally dumb questions, but there is just a lot to absorb, and I was hoping for confirmation that either I need to do a lot more reading, or I'm on the right track. Thank you to all!

edit3: answering a lot of my own questions.

Hi All. I’m looking for some input on the viability of using the SMSL SP200 THX 888 headphone amp to drive a 16 Ohm compression driver in my two way speaker. My two way uses an Eminence Kappa 15C in a Peavey FH1 bass bin, and Renkus-Heinz SSD-1800 16 Ohm compression drivers on Altec 511B horns. The compression driver will be used for frequencies above 400 Hertz. The specs for the SMSL SP200 show that the amp
Is rated at 6000 mW into a 16 Ohm headphone. This would seem to indicate that he SP200 would be able to do the job, as I would be unlikely to use more than 2 Watts normally, and as the compression driver is 16 Ohm, but I figured it’s best to ask just in case I’m missing something prior to ordering the amp. I have attached the spec sheet for your consideration. Any input would be appreciated.

Bought some power mosfets off ebay and they died within 10 minutes.
I unplugged my soldering iron and the glitch down the mains killed them.
So replaced them with genuine parts from RS components and amp is still working 18 months on despite loads of plugging in and out of items.

I looked for a LCD display at RS and cheapest one was £5.50.
I had a look for similar displays on ebay and found one for £1.74. So bought it and it worked great.
Wanted some 4700uf 35v caps and they were £2 each at RS but 50p if I bought 10 on ebay and these worked fine.

It seems care is needed if buying ebay or Chinese parts.
The power items sometimes have smaller dies and so pop easier.

D3a or 6E6P, Lundahl 1660 IT , and 300B.

Hi.

This configuration in 2 stages with interestage trasnformer, would be a good option?

Would be enough voltage swing for the 300B?

Thanks. Santiago

I’ve been running a few audiosource amp100’s in bridged mode for my active setup to get more power out of each amp for each driver. My question is what above ground really means when you are connecting the drivers to a dsp and then the crossover is done there.
so there is no polarity because both are hot because the amp is bridged?
I can reverse the polarity in the minidsp and get the drivers to sum the same way as a positive and negative.
The drivers I’m using for the bridged amps are 8ohm so no problem being bridged with halving the ohm load to 4.
is it a bad idea to have the amp in bridged mode for single drivers and trying to do crossovers in a dsp?
i used to run my towers in bridged mode but those where passive crossover towers.

I’m looking for a built and i want have it small because of my small room 🙂 please help me with the best components

planning to buy
JBL 2420 with azura 550
Tweeter?? With azura cone?
8 or 10 inch subwoofer

or small version of this.

please help thanks in advance

I want to power up the heaters of a pair of 27 tubes off a 4A 6.3V CT winding. I'd like to keep this as simple as possible using AC heaters, and am leaning towards series connecting them, with a dropping resistor between them and grounding the CT. Ballpark value on the dropping resistor would be nice to verify what I am thinking I will need.

Other ideas are welcome, especially anyone with experience working with 27 tubes. I'm planning to use them as driver tubes for a SE amp using 47 output tubes. I also have some 56 tubes if 27's don't stand a chance of being able to drive a 47. TIA

Hi,

I have an amplifier that won't dissengage the bypass of the graphic/auxillary RCA jacks when it's button is pressed.

Similarly it won't dissengage the tone controls when the Power amp direct path is chosen.

Both of these have small electromechanical relays to operate the switching of this path.

It's 1991 model amp.

What's the likelihood that these functional failures are because of the relay versus the connections to trigger the relay.

Also the board is quite dusty..

So... Electromechanical versus electronic versus connector issue.

Perhaps a good clean first ?

Perhaps the connectors from one circuit board to another?

Any ideas ?

Hi all,

a electronic company in germany sold the 2SC2922/2SA1216 for very low price (Only 1/5 of normal price in germany) . So i have bought 30 from this.

But now i´m looking for spice models of 2SC2922 and 2SA1216.

With google, i dont find anything. Can anyone help me to create spicemodels or know who i can find and downloade spice models ?

The Datasheets are here :

2SA1216 : http://www.tranzistoare.ro/datasheets/37/73327_DS.pdf
2SC2922 : http://www.ortodoxism.ro/datasheets/WINGS/2SC2922.pdf

thanks for all help

greetings

Dirk

Hi

Can anyone suggest free, or almost free, software for making a sketch similar to the one below? I copied this one from the mini dsp site.
I would like to convert my three way to active three way with dsp crossover. Making a sketch like shown below will help me.
Dan

Hi,

I want try to build a clean two channel's rack preamp based on AMT SS-11, but using ecc82 as a output stage buffer, instead a jfet like the original. Anybody can help me if I do something wrong? or avoid something?

Thanks!

Hi,

I have a great +/- 24 volt power supply I was hoping to use on a F6. Has anyone done this? Suggested changes? Any help would be appreciated!

Brad

The new border around the sub-forum on Home hurt my eyes and brain. It is an unnecessary detail.

I suggest a clean interface. It was good as it was. Dont make it like an internet first years home pages...

Its the content that should shine, not the GUI...

//

Today when I logged in I noticed that the font was changed for (I think) all forums. I like it, because it is a bit smaller and the eye can scan/read more post titles in the same space.

I have only one nitpick and that is that the particular font weight is a bit thin in this font size. Letters are often veyr slim and this makes it appear a bit like when the toner is running out on the laser printer - faint. Can the font weight be increased or a slightly bold-er font used? Just a thought.

Thanks to the mods for continuing to improve the experience here.

Hello ,can somebody help me please with calculation of tOSC (frequency) if i use RT=100k and CT=550pF. Formula in attached photo! Thank you in advance!

Another "Ultimate" in the serie...

A revamping of a prototype I made 18 years ago 🙄😱

A simple and compact mono block amp that waited, taking dust on a shelf, in need of reworking and improvements.

The beast, once refurbished today. The pen gives the scale :



I came to 2 possibilities with the parts available :

One with decoupling the preamp stage cathode before taking FB loop :


The other with no decoupling the preamp stage cathode and direct FB loop :


The PSU remains the same for both :


Comparaison side-to-side of the square wave oscillograms, in exact same testing conditions :



I went for the other, the non-decoupled, direct FB loop circuit. All things equal otherwise :

- it has a reduced bandwidth : 10Hz-40KHz instead of 60KHz. Given that the bass extension without distortion is 20Hz, no need to go so high.

- the total FB is reduced to 10dB instead of 14dB for the same input sensivity (0.7VRMS). Less FB gives less performance here, but smoother square waves, so possibly less harshness in the harmonics.

A friend of mine will come soon so we will be able to make THD, IM and harmonic spectrum analysis thanks to its software.

So wait and See if that choice is good or not... 😱😉

A+!

I've been looking at the ROAR and other similar designs a bit lately, and wondering whether a compact 8" based version would work. Using the MCM 55-2421 or Dayton dcs205 it seems workable, perhaps...?

Here is a hornresp sim of a scaled down ROAR10 with the MCM 55-2421. Predicted frequency response is...well, a bit peaky! But it seems not drastically different from the ROAR10, and can perhaps be improved upon. It would need to cross at around 150Hz for the intended application.

Diaphragm displacement is predicted to be nicely controlled at pMax (eg 21.91), staying below xmax down to around 40Hz. Only around 70 litres net.

I have some of these drivers lying around, and access to CNC, will be happy to share some measurements and so on if I end up building one or two...

Any thoughts would be welcome, cheers!

Hello DIYers,

For along time i have been a lover of the OHM Acoustics speaker company. I was wondering if anyone on this site had heard of them and was wondering what there thoughts were on the company.

Another question is, has anyone tried to replicate there landmark speaker the Walsh F?

I know the speaker to begin with was particularly difficult to build. It was also fuzzy. But if you were able to set up the WALSH "F's" just right, they sounded like a million bucks. some saying it is the best speaker ever made.

I was wondering if anyone was able to replicate this unusual design and make a speaker using the WALSH technology.

Thanks. 😀

Hi all,

I am going to build some new enclosures for my Monitor Audio Vectors V10 and V20 speakers

I have 2 of the Vector V20 centre speakers and would like to combine them into one. Can I just wire them in parallel on the crossover or will I need to change some components?

Specifications of the speakers:

Frequency Response​

60 Hz - 30 kHz

Sensitivity (1W@1M)​

85 dB

Nominal Impedance​

8 Ohms

Weblink for reference

I have added the pictures of the Woofer, Tweeter and Crossover.

Thanks,
Mike.

Here is something that is a bit interesting: When I designed the mid-HF satellites of my 3-way system, I modelled the diffraction of the mid driver and the tweeter with VituixCad2. These were built earlier this year https://www.diyaudio.com/forums/multi-way/366347-active-satori-textreme-9.html#post6523706

After building and testing the system, I found some small diffraction effects which were not predicted by simulation. These small +/- 1 dB warbles are in the 3 kHz – 6 kHz range. When I compared this to the previous mid-HF satellites (built in 2020 New active 3-Way, Hypex and SB ), I found the same differences between simulation and measurement. Now remember these are two different tweeters (Satori TW29TXN-B in the first case and SB26CDC-C000-4 in the second case)

I suspected that the culprit was the cavity formed by the 6” mid driver. The simulation of the tweeter in the baffle assumes the baffle is flat. Even when two drivers are simulated, the simulation accounts for the acoustical interference between the two drivers, but not the shape of the drivers on the baffle. I show a screen shot of the baffle diffraction simulation for the tweeter.

To understand what is going on, I did an experiment with the older unit with the SB26CDC tweeter. I cut a circular disk of cardboard and covered the mid-driver, taping it in place. Using tape, I made the transition from baffle to cardboard disk as smooth and flat as possible. It was not perfect, and the disk protruded above the surface of the baffle by about 5mm, but the there were no sharp discontinuities.

I then measured the on-axis response of the tweeter with the disk and without the disk. I was very careful to maintain mic position and test conditions between the two tests. In my plot I show the two measured responses, with black being the covered mid-driver which simulates a flat baffle, and blue being the system in its natural state. I also plotted the uncovered mid-driver normalized to the flat baffle measurement. I was surprised by the differences. The warbles between 3 – 6 kHz are present in both curves, but are more pronounced in the blue curve (uncovered mid-driver). But I was not expecting to see so much response differences at lower frequencies. From 900 Hz to 3 kHz, the effect of the uncovered mid-driver on the tweeter is +1.5 / -2 dB.

So I did not discover the cause of the 3k-6k warble, but I did find something interesting. I remember reading about this phenomenon either in a paper or in a book, but I don’t remember the details, and I believe it was a qualitative rather than quantitative assessment.

j.

Not sure if this is the right forum, but here goes....

I've been using some old Audioquest speaker cable for years. Now I'm rearranging my listeing space and need to make a splice. Not sure exactly which one, I can't find it on their website any more. Anyway, it's about 15mm OD. The construction is 6 18 ga. stranded conductors for each polarity for a total of 12 conductors in a spiral. Tne whole thing is pretty damn stiff.

I'm not sure what the best approach would be for the splice. I'm thinking maybe stripping of 6" or so of each end of the jacket so I've got 6" of conductors to work with. Then butt splice each conductor for one polarity around the circumference from one side towards the other while maintaining the spiral. IOW first conductor splice is closest to the left cable using ~1" and 6" of the right cable. Next splice is shifted over an inch or so (2" of left conductor, 5" of right conductor) etc. Then last splice is closest to the right cable with the splices forming a staggered spiral. Repeat for other polarity opposite the first splice. Hope this makes sense. I can visualize, but hard to describe. It seems like this would reasonably preserve cable geometery and make for the thinnest splice. I typically use WBT "silver" solder. Obviously everything would be sealed and covered with heat shrink tubing,

So, is this a reasonable approach? I guess I'm a kind of cable skeptic so impact on sonics isn't foremost in my mind. But maybe it should be, so thoughts or experiences would be welcome if they're concrete - I can speculate on all the theoretical problems with splices with the best of them. 🤓 That said, suggestions, comments and experiences welcome! Thanks and cheers,

Hi guys! Thank you for this forum. I am planning to upgrade my system buying this amp. Nevertheless, I am having some trouble understanding how these amps, the DIY Amp Camp Amp (8W/channel) could drive my speakers, rated at 140W long-term capacity into 8ohm. I even read that it’s good to have an amp that doubles the speaker capacity so you don’t push your amp too far and it distorts. Isn’t 8W faaaar less than 140W? Obviously I’m missing something here, since I’ve seen pictures of your this amp driving two big Klipsch Heresys. What amazes me more is, for example, the specs for a pair of Harbeth Audio SHL5plus are “150W programme, recommended amp power = 25W per channel). I don't get it. Could anybody enlighten me, please? Thank you very much for your help.

Laminated core output transformers are nonlinear. Due to the shape of the B-H curve, the primary inductance at low signal level is much lower than at the nominal max. output level. Let's keep below saturation.

The change of primary inductance has effect on low frequency cutoff of the whole amplifier. Global negative feedback could compensate it in some extent, but let's disregard it for now.

How audible is the level dependent change of low frequency cutoff? I mean it could happen that the cutoff frequency is as high as 100Hz @1mW output level, but it is 20Hz @1W output level and 15Hz @10W. Psychoacoustically, the human hearing threshold of low frequencies is higher at low level, so perhaps this effect of cutoff shift is not audible? Or is it?

While building (or designing an amp) in general what components would be the most important, and whats one (in general) would be mid importance, to low...
Since Im a 100% total newb, I have only a hunch. But just to see the format Im hoping to see in the responses I will start.

1) Layout and wiring technique, OPT quality, coupling capacitors, power supply and filtering, heater wiring and heater power supply, resistor and capacitor selection, biasing all of the tubes

Expand as required, and feel free to give your reasons or explanation...

I have Signetics 5534's from 1979 and 1980, but these are the earliest ones I've seen from another maker. But whose logo is on these? Is it Raytheon's? I believe they started second-sourcing the 5534 in '78 or '79.

Would this scope work for amplifier repair?

Here is my take on a mixed feedback chip amp.
Reason for creation: I need a bass amp for my OB speakers. Fullrange Wild Burros are driven by my beloved 4W flea amp (tube). The 15" woofer needs help... Attenuating the FR 6dB actually gives a great speaker just using the tube amp, even at movie levels. But you know...
Why mixed feedback... OB speakers need high Qts speakers. I may be misinformed, but I think having resistance in series w/woofer increases the combination Qts. Besides, a current feedback amp will have greater gain into high Z, and the 35Hz resonance of the woofer will then get more voltage over itself giving more low end... In my thinking...

Why not 100% current feedback? Why mixed... Well, I don't want to over do it. The resonance at fs creates a rather high Z, and in simulations I see the gain rising scary high, and I don't want the amp to run into it's rails.

This worked out pretty well. Done over the weekend, using some Cu print boards as GND, V+, and V- rails. The GND plane is good for freely placing components without worrying about return paths. Or put another way, ensuring lowest possible inductance in the signal loops.

Having built enough point to point tube amps, I figure no need for circuit board in such a simple circuit as this. I am too lazy to spend days designing the layout and having to wait for the prints to arrive...

I only had a transformer providing +-15V, so the power is not as much as what theses chips are good for. But next to my 4W tube amp, it'll just do.

20W into 4ohms and 12W into 8ohm. (Approximately, I never bother measuring this precisely because I cannot hear the difference in +-1or2dB anyways)

The final result is quite satisfying, even going full range and replacing my tube amp as I do some mods to it.

Hi,
so in my Corsa D car (2008) there was a DELPHI-GRUNDIG car radio, model CD30 with a TDA 7385 chip (at least based on what some forums said, since the chip is identified with an industrial code and not with the official name).
The sound was always very muffled and not very loud. It also was distorted at maximum volume, so after replacing the horrific factory loudspeakers I decided to upgrade the amp chip inside the radio: I decided to use the TDA 7560 which was the most suitable replacement because of the pinout compatibility, altough some modifications was still necessary.
I tought that the new chip would give me at least some more SPL, since from the datasheet the TDA 7560 is actually much powerful that TDA 7385. The speakers are 4 Ohms.
Unfortunately there is virtually no difference between the two chips: the volume is practically the same and the distorsion is still present at maximum volume. The only beneficial upgrade was the replacing of the speakers, the originals were really bad in quality.
Did I something wrong?

I have a single ended Tube amp I've been working on. I looking at a sine wave or the output transformer and it looks asymmetrical to me. The positive side of sine wave seems elongated. Attached is shot from the scope. the yellow line is the output measured across an 8ohm resistor connected to the speaker outputs. The green is the signal from the input tube, measured at the coupling capacitor where it goes to the output tube grid. I've tied to scale the two to make a good comparison, It looks to me like the input tube looks pretty even. But something wonky with the output. I looked at another amp I have it looks more even. So what does this tell me? What may be causing this? (note that using an Oscope is new to me so I'm not sure exactly what to take away from what I'm seeing)

Hello, I'm wondering what may be the effects of different layout in disposition of mid and tweeter in a 3 way system between the two following cases:


On the left a 'classical' vertical disposition, on the right an horizontal disposition for mid and tweeter. The question: may the horizontal be better than vertical disposition?
In my opinion the horizontal mid/tw layout may have two advantages:
- a better distribution of distances of drivers from cabinet edges;
- a better proximity conditions among all drivers;
What do you think about? Why is it generally preferred the vertical layout?

If it will be true that horizontal polar response will be asymmetrical, using two symmetrical cabinets I would be able to compensate the situation and rebuild a balanced distribution, isn't it?
Thank you.

Looking for a schematic for a Yamaha RX-300U sterao receiver... Any help would be appreciated.

Do you need a Grado maple tone arm? Do you want one? Here is one looking for a good home. $75 OBO. US shipping shouldn't be much more than $20. International shipping we can figure out.

The arm has been rewired with Mogami 4 conductor + shield cable. It's easy enough to use your own wire if you wish. It's a good arm for a low compliance cart. Note that is does not have the original counterweight (I never had it) it uses a hex socket instead. Nice and shiny. 😀

If no one here wants to give it a home, Rich Grado said he'd be glad to repatriate it back to New York.

I'm in search of a used Adcom 555 or 555II and I've found two GFA555 near me, but they are totally different cosmetically. Anyone know the story here?

Hi!
I have an unusual request - can someone, preferably from Japan or the surrounding area, help me buy these modules - want to use it in a portable amplifier for electrostatic headphones according to the design of kevin gilmore - unfortunately the same lt8365 chips are not available for purchase, so I was looking for ready-made modules from them and I found one, but in Japan. They are available, the price is also affordable, but there is no international shipping - the worst thing is that this company does not have an email address to contact, so I can't even ask them about shipping to Europe. I thought that there are definitely Japanese people here among the forum users and maybe they would help me buy these modules?

Hi All.
A neighbours friend came over recently with a pair of TDL Electronics RTL3 Loudspeakers which he donated to me.
How could I say no?
Externally they're in reasonable condition but missing the material which goes over the square ports at the bottom front of the boxes.
I pulled out the rear terminal plate/crossovers to find yellow poly caps fitted to one of the crossovers, but no additions on the other.
If anything the crossover which hadn't been upgraded appears to have missing parts.
I'm thinking, rather than try to work out whats been done and what's faulty or missing, I might try building crossovers from scratch.
These can be a mixture of existing parts with addition of new parts.
I'll need a crossover schematic but haven't had any luck tracking one down.
Any link or access to the crossover schematics would be very much appreciated.
Cheers Cliff

I've built a pair of mono 300b single ended amplifiers. They were working just fine but the filament voltage was too low so I invested in a Coleman regulator and that's all fixed now. One of them I rebuilt with the new regulator and works flawlessly. The other has an issue which cropped up after the rebuild. I'm not that experienced so I have a rough idea of what's causing the issue but I'd like to see if my troubleshooting process is correct and what you guys think may be causing this. As of right now I have yet to find the culprit and solve it.

As I power up the amplifier the B+ voltage rises slowly as expected to about ~430V where it's expected then suddenly drops at around ~350V. I knew the only tube capable of drawing so much current to drop the voltage that much had to be the power tube so I checked its bias and it's around ~150V which to my understanding is extremely high (therefore I didn't leave the amp on for more than a few seconds just to get the reading). I checked and the tube was thankfully not red plating and I also check the filament supply to be galvanically isolated from B+ ground. So I believe there's some issue in the biasing circuit, although it's extremely: just a 880R resistor which measures fine and is rated at 50 watts, and a 100uf bypass cap. My first though was a bad cap, but after taking it out of circuit it tests fine (could it be leaky though?).
Another issue I'm facing with this unit is that it makes some scratching noises as it powers up and even after "settling in" (albeit for the few seconds I've kept it powered with high B+).
I believe this may be related to the previous issue or be caused by some (new) cold solder joints. Any tips on finding those out?

I'll try swapping the capacitor for a new quality one if it's deemed to be the only possible cause of the issue.
I'll leave the schematic of the signal circuitry if it can be of any help. The PSU has been designed from scratch and it's just a simple CLCRC unregulated.
In the schematic an humpot is used, but now that I use a DC regulated supply I believe it can be removed right? How should I wire the bias without it?

Thank you for your time and I really hope I'll be able to give back to this community one day when I'll have more experience under my belt.

What does R47 ohms means

Why we need to pay attention AEC-Q200 reliability during car component selection ?

Car application component requirement :

1. Process traceable
2. Risk Management
3. Intelligence
4. Safety
5. Energy Saving

AEC-Q200 defines the test methods and additional requirements for magnetics, including inductors and transformers. These tests include a variety of methods to test the component's ability to withstand severe conditions, including:

• High temperature
• Thermal cycling
• Thermal shock
• Low-temperature storage
• Moisture and humidity resistance
• 1000 hours at rated temperature and current
• Mechanical shock and vibration (10-2000-10Hz，5G,12H)
• Constant acceleration
• Resistance to soldering heat
• Resistance to cleaning solvents
• Terminal force strength
• Shear strength
• Board flex

Stress test qualification temperature ranges established by the AEC-Q200 standard are categorized into five grades (0 - 4), as shown below:

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Hi!

Could somebody tell me What is the LL1517 good for?
Is it possible to use in tube circuit?
Something like the Raven preamp has in the input?

http://www.lundahl.se/pdfs/datash/1517.pdf

Tyimo

New or good condition

I play around a bit with Yamaha AV receivers (RX-V and RX-A ranges), and over time I have collected some faulty units with the hope of one day getting around to see if I can get them working again. I also had a couple of these fail on me - it powers up and most of the indicators come on and one can access the menus, but no audio, not even from analogue sources. It is typically not a sudden thing, from own experience and also from speaking to the previous owners where I got the unservicable units from. Often the receiver has audio only after a minute or two and would then perform perfectly therafter, and this minute or two then increases over time until you simply do not get any audio, unless you are lucky and it only works on "Direct", like the RX-V675 in my shed 🙂.

I would hate to bin any of these so it is time to give it a go. Following some research it appears that the DSP chip typically gets a bad solder contact over time, and the chips are often no longer available and if you could get a new complete board, the price makes the repair non-viable.

Has anyone had experience in sorting out these bad contacts, if they are indeed on the DSP chip, which is typically a surface mount chip for which you need a magnifying setup to see the pins clearly. I do have a hot air rework station and some other electronic equipment.

I also read this thread which was not too dissimilar to my situation:
https://www.diyaudio.com/community/threads/yamaha-rx-v367.224529/

Looking for a blank Salas SSHV2 pcb.

Regards
Rents