Wise people of the forum ..

I'm building a tube preamp and need a good two channel pot.

From what I can gather there are different types and many good manufacturers.

What recommendations would you have in terms of:

• Stepped or not?
• I understand that with non stepped pots, there are different compounds that are used - conductive plastic, cermet. Is this a good path to go down?
• Brand - Alps, Audio Note, Bourne, Vishay etc etc

I'm probably going to need a 100k pot. Space inside the unit is not an issue. Price? - I'm looking for something in the mid to upper range of what's available.

From the research I've done, there are many options, however, I'm aware of my limited knowledge in this area (hence looking for recommendations). Are there any other questions I should be asking? (I don't know what I don't know! 🙂 )

What are your recommendations and where can I source the pot?

Thanks

I am refurbishing an old vintage tape recorder. Its headphone amplifier is an NJM386. Is there a better alternative?

I was referred to Tang Band through a friend in the business, and the president of the company sent me a pair of the W4-2315 4.5" coincident drive units. I recently completed them, showed them at PE's 2023 Speaker Design Competition, and have been thoroughly pleased with the results. These are not yet available on North American soil to my knowledge, and these units are fairly new. The off axis plots they sent me were taken Jan 4, 2023.

Name Monoculus arises from the daisy flower affiliation and the fact that oculus relates to ‘eye’; both of which relate to the look or aesthetic as well as function of a coaxial drive unit. The Tang BandW4-2315 (2315) coincident driver used herein is specially designed to try and minimize or suppress problematic hindrances such drive units usually employ. To keep the active motion of the midrange portion of this driver relatively low requires instead the addition of a comparable woofer to dredge the both deep and moving bass lines. I chose the Tang Band W6-1139SIF (1139) for this task. This driver is small enough to reach high enough in the lower midrange area, as well as not requiring a lot of box volume to yield low enough bass extension.

Since I had cabinets I had already made that utilize replaceable baffles, I chose to make this 3way combo work within this size constraint. I call this my VersaBox, and it has a volume of just over 15 liters to work with and keep losses from bracing, mounts, crossover parts, and drivers to a minimum. In ~13.5 ltrs after subtracting 1 liter for the midrange chamber, the 1139 will yield an F3 below 40Hz for tunings below 50Hz with heavy fill. The 2.5” port diameter is required to keep vent mach noise at minimum, and tunes to 47Hz. The port outer exit has a 1” roundover. By using said VersaBox, I have a limited depth requirement that can’t be exceeded, and I chose to keep the inner end of the port more than 1” away from the back of the midrange chamber housing. I also used a wool-felt-lined 4” PVC end-cap for the chamber. This then required the use of a thicker baffle material to keep the drivers’ relative positions further removed from the cabinet volume.

My home has an old outbuilding farm barn that has seen better days. My father (mainly) and I have slowly worked to bring it down so that it does not fall down onto my adjacent garage. In this process of bringing down this structure that was raised in 1896, a plethora of old wood supplies has come to me. I selected a piece of floor joist that is roughly 10.5” wide x 2” thick by length required of old and hard white oak. I had to shave the rot off the edges, square up the dimensions, and flatten the facing curves. I ultimately did the last step 3 times due to the boards cupping twice before I coated and sealed with epoxy. I initially had the driver mounts CNC’d, and then basically had to start over and recut them after the boards moved. Suffice to say, much work was done to get them in a usable state. End result size was just less than full width of my VersaBox inset rebates, but ultimately still looks good to the eye. Normal baffles used in this box are 12 7/8” x 8.5” and ¾” thick. The Oak is 1.75” thick for comparison. I finished the Oak in Danish Oil and followed with oil based polyurethane for the visible dimensions. The rear non-visible half is just coated in epoxy.

The Main portion of the 0.75” thick MDF VersaBox was before this, unfinished, save for 2 coats of epoxy and a light sanding. This left the surface easy to prep for paint. I used Krylon Fusion Primer+Paint for the base white, followed with Duplicolor Effex for a metallic shimmer, and ended with Duplicolor 1K clear gloss. Note that I have glazed over a bunch of prep steps, sanding, sanding, and more sanding, as well as the problems encountered during this process and the dry times inherent. Arduous is definitely the word, but worth the trouble for the results. I finished them before taking measurements so that I would get them done and not have to take them apart again.

I used the Smith and Larson WT2 for impedance measurements as well as T/S, and the Dayton Omnimic for the frequency responses, harmonic distortion plots, et al. Off axis horizontal plots were extensively taken. Crossover modeling was done with my late friend Jeff Bagby’s Passive Crossover Designer Microsoft Excel based spreadsheet suite. I used Bill Waslo’s Xsim software to plot the off axis curves and draw the crossover schematic.

Resulting crossovers came to 400Hz LR2 and 4kHz LR4 respectively, and utilized 14 component parts to get the job done. Crossover boards are 6” x 7”, and stacked to about 4.25” thick at the most. Due to the component types used, they are also roughly four to five pounds of heft. The midrange breakup on the 2315 was measured as more benign than the spec sheet shows, and therefore a simple 3rd order electrical lowpass sufficed. However, the cavity resonance of the midrange in its chamber came to about 30 ohms with a Q of 1.0, so I had to take care in removing it in the network. I initially tried an LCR series notch, but omitting the R component and relying purely on the coil’s DCR with the additional cap was all that was required to suppress it heavily, and impedance remained benign. This meant a single cap could be simply used as the highpass component. Being that the tweeter is only a 20mm, I also used the midrange highpass to cascade into the tweeter section of the crossover for more protection. The crossover for the tweeter (post-cap) consists of a 2nd order electrical network, and series fore resistor and after shunt resistor. The resistor across the tweeter was added to aid in Fs suppression, as even though the Fs is minute in magnitude, it seemed to be audible without it. The woofer was simple with a 3 component damped 2nd order lowpass. Harmonic distortion is very low for the tweeter, and low enough for the midrange and woofer that it should not be very audible in their utilized bandwidths.

I did play with the various styles of using coaxials in terms of placement, facing direction, whether to optimize for 10-15 degrees off axis or for on-axis, etc. I found I could not lift the top octave for facing straight forward use because they always sounded bright in this application. The normally present dips in the tweeter response that are due to the waveguiding midrange cone are very narrow for the 2315, and really vary in orientation as you change the applied toe-in or not. I found that I didn’t find the treble response unpresentable in any facing placement direction, nor did it really get worse in response until beyond 60 degrees off axis to the point of being audible. I typically have them positioned where I can look down the inside side of the cabinets at the listening position, or toed-in but not to the point of having them facing the center of my skull.

The result is a fairly uniform directivity, small but not diminutive stand mount monitor speaker with about 80-81dB/2.83VAC sensitivity, fairly low inherent distortion, 4 ohm impedance, bass to F10 of 25Hz, and a clean and detailed sound pallet. I have to say that these really surprised me at how resolving they can be in terms of complex music. They are very coherent, image very well, and soundstage is not small. I feel they are one of the more resolving and pleasing designs in my growing repertoire. I have been enjoying them immensely. They are also very appealing visually due to the old wood baffles and smooth metallic white gloss paint job.

A few weeks ago now, at the Parts Express sponsored Speaker Design Competition in August of 2023, these were judged by 3 professionals in the industry, and netted a score of 147 out of 180 total points. This was in a tie for 2nd place initially, and there was also a tie at 150 points for 1st place. Due to tie breakers, this made this entry’s finale to be 4th place, but also totally valid to state it tied for 2nd place.

I also would like to thank Tang Band for the opportunity to work with the W4-2315 drivers. The experience was very favorable for me, and their support of their product was fantastic.

Thanks for looking,
Wolf

Thanks to Bill for the photo....

Very top of the line tuner in perfect condition. A shame to scrap therefor looking for someone that wants to use it.

20 euro plus shipping.

My friend has sent me the U frame of Acoustic Elegance Dipole 18 and it's measurement.

Anyone has built one before.

What's your thoughts?

Thanks 😊

Hello all , introducing my self as a vintage Sansui enthusiast!

Hi there!
Thank you for clicking on this post.
I have been trying to find a FIR filter (including coefficients ) example ( not create one! ) which is used for audio devices ( such as speakers ), which conform to audio standards ( such as AES17).

Specifics of the type of filter I am looking for: https://www.audiotech.com.tw/AES17 Filter.htm

I've looked at multiple DACs to find an example filter, but to no avail :/
Hope experts like yourself can help me here.

Samster out

Good afternoon, I am looking for a European equivalent of the 2n5550. A transistor with low current and high voltage Vce (100V or more). Is there one of the BCxxx or MDxxx type?
Thank you

Looking for this shielded transformer new or used, if anyone has a spare.

Preferably from within Europe, but depending on shipping cost world wide is possible too.

Hello,

While searching the net for spice models of the MJ802/4502 with no luck, I had found the discussion:

http://www.diyaudio.com/forums/newreply.php?s=&action=newreply&postid=54012

I would like to repeat Mr.Self simulation, but could not find the models. Could you please push me in the right direction?

Dimitri

mod Naim CD-player with PMD-200 into stand alone DAC: please help!

As the mech of most Naim CD-players can't be replaced any more quite a few of these machines will become useless in the coming years. Owning a CDS3 I wonder if it would be very complicated to carry out a mod to re-use it as a stand alone DAC.

Looking at the schematics found here I guess the PIC16F629 just configures the PMD200 for 44k/16bit and that's it. There is another bigger mcu which controls the drive and resets the PIC16F629 (the schematic says to issue a re-sync): this mcu would run all the init routines (i.e. setup the drive according to some test measurements etc.) and after success would allow the PIC16F629 to setup the PMD200. The PMD200 can be run in hardware mode but only with 44k/48k, other sampling rates require software mode.

Replacing both PICs would allow the use of the LED display to show information such as bit depth and sampling rate. The only other things needed would be a second clock for the 48k based rates and a USB bridge. But I am afraid this kind of mod would overwhelm my skills… What do you think?

I have both the essentials and completion kits for the Iron Pre SE, just as they came from the store, complete with Cinemags, now going spare.

Looking for a UK sale preferably.

£200 plus postage at cost please.

Can add some pics tomorrow.

Cheers

Ian

Im picking up an Eclipse DA7232 amp which I believe is using two 1000A Icepower modules from Bang & Olufsen. Not much around about these, but the modules appear to be available to buy online.

Anybody have any experience with this type of design? Im not even sure what may be wrong with the amp, just checking here first before I take possession. Im looking to make a match with an eclipse 4-channel amp i have.

Thank you

I acquired this integrated amplifier. The shielding on the single-ended input jacks has been pulled off. I've already removed these from the board and am looking for parts that will fit. I've already contacted Krell. They were very nice but not able to help. I've searched Digikey, Mouser, AliExpress, etc. and haven't found anything that would fit perfectly without modification.
As far as modifying parts that I have found goes, that would involve trimming off the screw hole on one side of a connector that has screw holes on both sides or it would mean buying a 2x2 and 2x3 and not using all of the available screw holes in the chassis. Maybe there are other suggestions?

I'm wondering if anybody out there knows of where I might find the right part OR has any ideas about how to otherwise make this work? TIA, mfaughn.

In perfect working order. A discrete phono stage with parallel jfet input.
Power supply with 3 stabilisation stages.
Asking 250 euro including shipping in EU.

Images to follow.

Hello,
I am looking for Diyinhk Akm 4497 pcb board with dac chip.
Thanks.
Greetings, Dezso

In perfect condition. With remote, user and service doc. Images to follow.

Make me a fair offer !

Hello,
Does anyone know what these capacitors do? 6x 1000uf 25V

Assume the target is to let the woofers play louder than the midrange and the tweeter, in three ways speakers. Instead of applying the L-Pads to the midrange and tweeter, one way I could figure out is to add a second woofer in parallel with the original woofer. This will affect the SPL of woofers’ section by increasing it about 6dB. However, if I want merely 3 or 4.5dB, is there any approach to achieve the goal, without introducing the L-Pads or any attenuations on MF and HF drivers?

Got this cd on Amazon (came from Greece). Nice addition to my modest jazz collection. Very good live recording.

Dear Experts,

Kindly suggest to me the values of capacitors, inductors, and resistors for the AI recommendation below for the Aiwa NSX_V900 speaker system!


For a crossover upgrade, I'd recommend a Linkwitz-Riley (LR) crossover design, which is a popular choice for its smooth, linear phase response and excellent impedance matching.

Here's a suggested crossover configuration for the NSXV900:

• Woofer (5.25"): 12 dB/octave LR crossover at 250 Hz
• Mid-range (4"): 12 dB/octave LR crossover at 2,500 Hz
• Tweeter (1"): 12 dB/octave LR crossover at 5,000 Hz

In case it's of any interest Rapid Electronics in the UK list the RK27 in their clearance section currently:

https://www.rapidonline.com/alps-rk27112mc-100k-motorised-dual-gang-rotary-potentiometer-66-0227

Could be useful for a Whammy amp build, even if the motor isn't used.

Friends,

I've started writing the occasional short piece, a column really, for the weekly free AudioXpress newsletter The Audio Voice.
Several people suggested I post them here at diyaudio as they may be usefull to members.

So, here's the first one, on feedback. Please let me know what you think of the idea to post more similar pieces, but also if you have comments on the contents.

The free TheAudio Voice is published every week on Thursday. Subscribe to the newsletter - it's free and there are always unsuspected gems about audio!
There's a sign-up button here.

Your opinion is appreciated. And if you have suggestions for future columns - let me know!

Jan

Started my Frugel Horn build, have all wood cut and sides shaped. As a starting point does it only need 40g of damping at the front and back only. Using Pluvia 7.2 HD drivers.

I come to you at 62 years old having spent 25 of those years selling good audio and the other 37 years buying it back! Trained as a purist by Terry Crabbe of Sound Hounds in Victoria BC Canada. Started hanging out there when I was 12 years old and essentially grew up there.
My system at the moment consists of an Oracle TT with a Syrinx PU3 arm and my life long companion a Denon DL103 moving coil. Plugged into an Audio Research SP 10 preamp fully updated and capped with VH AUDIO which feeds a pair of tricked out 600 watt VTL amplifiers that seem to please my Magnaplanar 1.7i’s each with its own REL Subwoofer. The early version of the MARANTZ Super Audio CD PLAYER. Made my own interconnects with Levinson silver wire and WBT termination. Two dedicated 20 amp circuits one for each amplifier and a third for everything else. The Oracle is suspended from the ceiling and my REL’s are anchored hard into the floor. I’m about to bust out my Threshold Sl10 preamp because I just lucked into the one component I have always wanted since listening to it at the 1980 Vegas CES Show. I just stumbled into and purchased 4! Not 2 but four Threshold Stasis 1 amplifiers that I haven’t recieved yet. I feel like a boy on Christmas morning I’m so excited to get these beasts.

As someone who would likely prefer final acoustic slopes no higher than 3rd order, I'm interested in this topic.

I've observed that 1" compression drivers on horns often exhibit a roll off at about 26 dB per octave below their natural cutoff. Therefore the only way to achieve a 2nd or 3rd order roll off would be to cross well above the cutoff (at least 1 or 2 octaves), and live with the steep slope further down.

However, I've noticed a few compression driver/horn combinations, usually of the larger variety, that have a shallower roll off. For example, the Celestion Axi2050 mounted on an SEOS 30 (from Celestion's spec sheet):



As you can see, the roll off is only 12 dB per octave, starting at about 600 Hz. While other horns of similar size may often begin to roll off at or below 400 Hz, those other horns usually have a much steeper cut off slope.

So, is this shallower roll off characteristic achievable from a smaller 1" exit waveguide? If so, how? And are you aware of any available horns/waveguides that accomplish this?

One more thing:
Didn't Geddes use a 6 dB/oct electrical filter on the compression drivers in his speakers? I had always assumed at least a 12 dB/oct filter was basically mandatory on 1" exit compression drivers, even in a home/consumer setting. But if that worked well for him, I don't see why not.

Any thoughts?
Thank you. 🙂

Hello,
I have PCM1702 in my DAC, but I don't know what grade it is(J,K)? I'm confused because it has two marked dots?
Thx!

Selling a quad of unused Marconi ML6 single triode tube in white ceramic base. Bought a couple years ago but no plans to use them yet.
180USD shipped. Will ship registered+ tracking.PayPal FF only please.

Datasheet showing ML4, which is similar to ML6 except heater voltage (ML6 heater 6V vs ML4 heater 4V).
http://www.r-type.org/exhib/aac0035.htm

TUBES SOLD

Have a quad of 46 Directly Heated tubes for sale.
They are unused , in their factory boxes. Tubes have the same lot number and internal structure. Boxes conditions is bad. Tubes are in great condition.

Decided to sell them because I am aborting DHT amp project . These have dual grids and grid no.2 can be connected to plate to work like a DHT, to work in Class A ,almost like a 45.

I have no way to test them but the original owner of these mentioned that they have close readings and matched satisfactorily. I cannot guarantee this though.

160USD a pair , including shipping registered + tracking.

300USD the quad, shipped registered+ tracking.

PayPal Friends family only please.

Looking at a schematic from a C Audio RA series amps. I noticed there is capacitors placed between the pots. Is this to block DC that the pots could create? Schematic attached:

I am currently using a Rane AC23 to run 2 - 3 way speakers. I am not completely unhappy with the sound but I would like to try something newer. I have read some of the info in the thread about this item But I have questions for those who are using it. I am 71 years old and I cannot solder without burning myself. My hands shake badly and attempts to medicate made me a zombie. Is there any one here that might build what I need for a simple set up? Any idea what it might cost? thanks for your consideration.

This is the output filter section of the TX-NR1010/3010/5010 DAC board:
This is the recommendation from TI:

So in addition to the filtering in the I/V converters and the diff amp, they used an extra four op-amps per channel for extra active low pass filtering. Any idea why they deemed this necessary? With the noise shaping in the DACs, there should be little HF junk to filter out, and a simple passive low pass is probably better at handling HF junk than these slowish op-amps.

Hello everyone. I've been an electronics technician for 30+ years. Just introducing myself

Hi, first post here - thought I would share my Duane Brown's "Dayton 4's" i built around this time last year.

I had been wanting to build some bookshelf's for a while and had Paul Carmody's Overnight sensations on my list for some time after a friend linked me to Jeremy Young's build. The other one that jumped out was the Parts-Express C-Notes.

However when i added all the parts to the cart, with shipping it came to ~$290usd (~$470nzd) which put both of those options out of my price limit I had set of around $300nzd. Eventually I found out about the D4's (and the "deluxe" version) - which were specifically created with a small budget in mind while promising to still be decent. And at ~$280nzd landed they certainly fit the bill (this excludes the cost of the wood, which I had on hand).

I had some Rimu I had saved from doing some renovations that I thought would look nice as the fronts for them


And I adjusted the original box dimensions a bit so I could add some square stock for more gluing surface while keeping the original internal volume

(probably wasn't required, but it gave me piece of mind).

I 3d printed the ports (again because I'm cheap - but I have the tools, so I couldn't see why not)


The faces were routed out using some temporary jigs with the rimu double-sided taped down to some old mdf


The body's were primered and then spray painted with Honda champ white (I had it in stock 😉 ), and the front faces were waxed



Here's the tweeters and woofers going in:


Ports and posts installed:


Crossover in place:




And all done:



Super happy with them, I listen to them almost every day. They sound so big for little speakers!

My gainclone amp I threw together from parts I had sitting around many years ago has since given up the ghost driving these, so I will need to rebuild it properly at some point. And a friend has offered me some JVC "woodcones" for free, so I'm going to have a crack at designing my own box and crossover for them next.

Hi,

i need your help. I have a clone of fp10000q on my bench with a strange problem. On channel 3 when there is any signal it immediately starts cliping, the VPL/Clip LED come on and the output is low and distorted. I have checked the output with scope, you can see photo of good channel and bad channel. I looked the board for some burned resistors, measured all capacitors and everything seems fine. The problem is on the amplifier board, i tried switching the outputs from pre amplifier board and the problem was still on this amplifier board. Can you please direct me on what to look for or did someone have a similar problem that he solved out?

Thank you

These are for sale for approx 550 dollars here in Norway:

https://www.finn.no/358662706

Almost impossible to drive, and almost impossible and very expensive to refurbish. But van they be worth it at this extremely low price? He says he will throw them away if nobody buys them. But are they even worth it if free?

He has little information about them, he got them as partial payment for some stuff a few years ago.

And, can any FW iteration drive them? BBA3 monoblocks with cascoded FE and a bit higher rails, or F5T V3? Possible?

Found them at chance, needed some input, friends.

Picked up a Denon DP-80. It ran fine for a little while then started making noise. It's not a bearing, it's the motor control 'jerking' on the motor. I replaced the electrolytic caps. I also replaced some diodes on the motor control board because there was noticable corrision on the leads along with a couple of transistors on the quartz servo board because the leads were black and they looked rough overall. Did the speed adjustent with a scope.

Runs great at 45 but occasionally stutters on 33.

Here is how it sounded initially
https://drive.google.com/file/d/1LQUzwEly-sIBxaW-U55pbDstA6bEyhF3/view?usp=sharing

These 2 videos are of 33 after doing the work. Much improved but stutters (turn the sound up, it's not nearly as noisy). The scope traces jump when the noise occurs and the strobe display does too.
https://drive.google.com/file/d/1itKhF_dauQXwIodlL1Oz-82OCIjfrppY/view?usp=sharing
https://drive.google.com/file/d/1_Pc-AP2z49s9yn5m7XSSJbhTaAYmxHuo/view?usp=sharing

Any ideas? Thanks

Edit - it now does it on 45 also. Initially it didn't or maybe I just didn't run it long enough to act up.

Kevin Looker

I use DM7 in a active 3 way setup with Roon and Audiolense.

I have a little more noise with DM7 than with other DSPs. The horn is JBL2384 with JBL2451 with Truextent beryllium diaphragm. The amplifier to the horn is Anaview AMS0100 with 20 gain.

I can see that it is possible to individual adjust volume on each channel directly on the unit, will it help?
And it is possible to choose between 4 and 5V. I think it is default 4V in my setup?

Or maybee i should use a 10 dB XLR inline attenuator? Or a series resistor on the compression driver?

Any other suggestions?

I prefer experience in the answer 🙂

The thought struck me of building my own power distribution box with a surge protector inside. Then I thought, why cant I just build my own surge protector from scratch? Then I thought, if I'm building my own circuit, why not incorporate some filtering as well? Note that the goal here would be a fun project/experience more than practicality/cost savings.

Is such a DIY project safe, or is it best to leave surge protection to the certified professionals?

Are there resources/guides/discussions about building such circuits I could reference?

Is this even the right forum for this discussion?

I Wanted to let people on here know that I am selling these very rare JFETS on ebay. Genuine Toshiba parts with positive Feedback from previous buyers to prove it.

https://www.ebay.com/sch/i.html?item=126478126974&rt=nc&_trksid=p4429486.m145687.l2562&_ssn=jsaarl

I have been trying to connect two amplifier boards that I took from some mobile speakers. What I want to achieve is to be able to connect to only one via Bluetooth, and have it connect to the other as well.

Both boards have Bluetooth signals as input. Try to connect the antennas of the two boards, so if one of them received the Bluetooth signal, the other would also receive it.



In the photo you can see the idea I had. In the photo you can see everything already disconnected, but I tested everything well soldered, with the two boards on, with each one with its respective outputs, and connecting via Bluetooth to only one.



What I thought was that it made a lot of sense, and that it should work, but no, I only heard the output of the board to which it was connected via Bluetooth, and nothing from the output of the other board.

Does anyone know how this could be done?

Sale 6N9S=6SL7 metal base - 50 pcs. for $50/pc.

Greetings, ive been planning a Class D subwoofer amp using modules as its cheaper then buying say a Dayton Audio plate of equal power.
My original plan was to use a stereo TPA3255 board, and just use one channel making it possible to be a stereo subwoofer amp with a PSU upgrade. But today i found THIS IRS2092, IRFB4227 module for cheaper, but needs split power and not a cheap MW switch mode. AS-4440?

Does anyone have experience with those IRS boards? for 4 Ohm subwoofer use would i get any more power using it instead of a TPA3255? i believe the TPA3255 at 4Ohm 1% 51V gives 250Wx2.

Sale closed. Thxs 4 ur interest.

Hello everyone!
I hope I'm going to enjoy reading and posting in this forum

Abbado 2 NOS DAC details here - Abbado 2

2 DACs available. Excellent sounding DAC, ready to play. Just need 9V supply and an input module. The boards have some upgrade capacitors-

ALL SOLD

Good day all, plse give some advice. I got a Technics su-v5 integrated amp. The tone controls does not work on one channel, not bass or treble. Can it be only bass or treble faulty pot that makes both not work ? The tone control is in the feedback path. I have not taken the pots out to test them yet out of circuit. I cannot think of much other that can cause it ? Right channel works fine, bass boost work fine on both channels.
Regards
Jan

Currently I have a Pass Labs X5 driving my Dynaudio Special 25's via a BOZ. I hardly listen at very loud levels but listen to jazz blues etc... at decent volumes.
I am currently planning to build a pair of Aleph JZM monoblocks in the original Aleph 3 chassis's. Probably 80,000 uF in each monoblock.
Curious if anyone has used the Dynaudios with the Aleph 3 and how would the combo sing.

Hello. Does anyone have the Pascal S-PRO2 application manual? Could you send me the file?

Hi, I am new to the community and looking for some enlightenment with a amplifier/receiver that doesn´t want to work anymore. (will look for the right section for posting)

Other than that, I am into computers, somewhat hifi audio (I guess not as knowledgeable as many of you, but I do like having a receiver/amplifier instead of just a random wireless Bluetooth speaker), and DIY-ing as much as my skills allow me.

Hope to find the required help, and hopefully, someday will be able to help someone else.

Greetings!

Hello I am new to the site and am hoping someone with knowledge of the Luxman Lv105 can chime in with some information .. I purchased this unit as a fixer upper ,I have a LV103 and love it . Had a chance and a Lv105 not the U version , for very cheap because it's been messed with by a real hack. Anyway my first problem is getting a usable schematic for this amp ,I downloaded one but the numbers on my board are not the same as the schematic making it impossible to get your bearings . first thing I need to identify is a resistor on the protection board , it's been removed for some reason so I have nothing to go by .. on the board it's printed R-7376 . More questions to come but thought I would start simple . cheers and thanks in advance for any help .. Roger

Hi guys
Unfortunately one of the 2 mono volume pots on my vintage preamp broke off at the legs yesterday .
It’s Bourns 51CAAE28S20 which are no longer made .
The problem is that it’s shaft is only 3mm in diameter so I’m struggling to find a replacement
100k
3mm shaft ( 15mm in length )
Mono
It had 3 legs

Hello everybody,

I have an Eve Audio subwoofer in my home studio with an amplifier that died on me years ago. I have recently made the decision to order a new plate amp and retrofit that into the cabinet. (https://www.aliexpress.com/i/1005005492071000.html)

The amp only provides a single channel output instead of stereo, therefore I'll need to connect both my mains and the subwoofer to the soundcard requiring a total of four outputs.

So my question is: Do I require an active splitter kind of device or can I get away with a pair of Y cables?

(I am using multiple eq's for room correction etc. so I don't worry about the absence of a crossover)

Hello,
I have been passionate about self-building for many years and I like to build everything in the hi-fi and car audio fields. I have built loudspeakers, amplifiers both SS and valve with good results and I would like to be welcomed in this forum to share my experiences and receive support.
Thank you

Hello everyone! Excited to have discovered this community.

I have a small pile of DIY projects. I recently refurbished a pair of ADS 1590s to near-mint, and currently listen on a custom pair of transmission line speakers that I designed and built. I'm at the shallow end of the pool but hoping to build or refurb a preamp and amplifier this year, along with a server for hifi streaming from my collection. Wish me luck 🙂

Hi all, I was given two of these yesterday because both voice coils are rubbing and my buddy was throwing them out. I can replace the voice coils with no problem but I'm just wondering if anyone can tell me what they are. They have a square ferrite magnet and a super cool cast basket. Thanks

Both kits complete and unbuilt with all parts and boards.

I bought the Iron Pre and the Iron Pre essentials kits but have since gone off in a different direction before building.

My cost was $235 plus shipping.
Make me an offer I can't refuse.
I'd prefer shipping only within the US.
International shipping can be a real hassle.

Thanks!

What's the purpose of the recessed midrange some manufacturers do?
Small waveguide?
Only for looks?
Anyone tried it?

Some simulation results investigating TPC/TMC/‘pure Cherry’ and other obfuscating stuff. This started out as an exercise to see if LTspice can simulate ‘real life’ stuff from when commercial PA design was important to me.

 I hope yus gurus will use it as a base point for some of the ‘compensation’ discussions in the threads on Bob & Doug’s books.
 I’m also hoping Bob & Doug will be encouraged to do more ‘real life’ work on ‘pure Cherry’ rather than declare it unworkable.

Starting point is Douglas Self’s fig 6.16 from his 4th ed. cos that’s close to what I was playing with in 1990. I’ve used Bob Cordell’s BJT models and some FET models from Scott Wurcer. These give the worst results of any models I can find so are likely to be close to real life. I’ve used mjl21194/3 cos they are the worst of Cordell’s OP devices and closest to Self’s mj802/4502 and the Sanyo device I used. This gave Self'’s results for THD with frequency … and also what I remember from 20+ yrs ago, which was encouraging.

Remember, all dis theory en simulation is useful … not cos the mathematical rigour or how it supports some pet theory .. but ONLY if it has some connection to ‘real life’ and gives us insights into the behaviour of amps and how to improve / design them.

Self & Cordell’s books are useful … not cos they expound many theories … but cos … for their pet topologies & ideas, they show ‘real life’ results from their experience and relate them to the simulations and calculations. eg asking Self to pontificate on the virtues of CFAs is non-productive. He doesn’t see the virtues … and more importantly, hasn’t done much ‘real life’ work on them.

I check virtual (and real) stability with a large variety of loads including pure capacitance from 33p to 100n as described in http://www.diyaudio.com/forums/analog-line-level/218373-discrete-opamp-open-design-231.html#post3266142
Some tweaking of stability done with added ‘zeros’ with judicious use of C2/7/9 and .TRANS. Check if C4 across the ‘bias spreader’ is appropriate and if something across R15 is needed.

BTW, this is all stuff you check & tweak in ‘real life’ … eg if you change devices in production

The Open Loop responses are done with a Tian probe (LTspice4\examples\Educational\LoopGain2.asc) at the –ve feedback point. Connect R5 to Ground for this. .AC closed loop responses (not shown) to check for excessive peaking. Connect V2 to R5 for this. For these and plain .TRANS, you need to get rid of the ..

• connection between InN and the base of Q3
• U1 the THD meter

Of course, a Tian probe measures Loop Gain at that point rather than Open Loop. My apologies to da pedants.

First off is Two Pole Compensation (TPC) around the VAS. I’ve sorta used Cordell’s method by splitting Cdom and taking a tweak resistor R23 to earth. C7=4p7 from the stability tests.

Distortion at 20V into 8R up to 10th harm. using Eugene Dvoskin’s Total Harmonic Analyzer from the LTspice Yahoo Group including stuff from jcx. The distortion residual shows 2 cycles of 20kHz with the fundamental superimposed at 0.01% to give some idea of scale. Ignore the lower freq waveforms. Takes a long time.

A simple headphone adapter for a tube amp is non-inductive 8 ohm resistors placed across the outputs and then another resistor to each channel of the headphone jack to knock the output down a bit. Are there any commercially made amps that could be damaged by this because the outputs do not have a common ground?

I read here some peeps running 3c24 at 400V / 15ma - less than half of the rated anode dispersion...would these tubes:

1. Sound any good there?
2. Live very long there?
3. Be all good

For sale and located in Copenhagen, Denmark. Can be shipped inside the EU.
I got a 19" rack from a local TV-station that went digital. All are soldered to a printboard inside and connected to 2 plugs.
Suggest a price of 22 Euro each ~ 264 Euro for the lot, rack and all.

Hi all, i have a load of old woofers sitting around and ive been studing hornresp for a few weeks now, issue i have is that my subs appear to be cookie cutter chineseium and are missing a bunch of the parameters needed for hornresp.
I have a DATSV3 and that, also, doesnt give me the parameters i need.

My question is, given that ive designed a horn that im reasonably happy with (96-100db from 26-80hz), is this planned response then irrelevant without the driver parameters, or will be be close, but not accurate?

I have the SD and the LE from the dats, but virtually nothing else and i need SD, BL, CMS, RMS, MMD, LE, RE.

Thanks in advance,
Adam,

........ watching for too long.

Assume I have a pair of dream speakers, called speaker A. I don't own it but, instead, I have a similar model belonging to the same brand, speaker B.

I've been playing with simulations of two crossover circuits that are different from each other. I tried tweaking the crossover values on the simulator of the speaker B until the frequency response graph matched that of the speaker A. I know there are more than FR graph to be considered but somebody had told me the FR graph is indeed the final result of all graphs. In other words, any other graphs will affect the FR graph at the end.

Attached are FR graphs of speaker A versus modified speaker B. Note that it's my intention to create the curved/ugly FR graphs--for educational purpose.





Is it possible to make sound of speaker B similar to speaker A by duplicating the frequency response? I'd love to hear the inputs.

Can I use Caddock MP-930 (with heatsink) in the passive crossover?

What about parallel three Mills MRA-12 for target value?

For some DIY audio enthusiasts, the thought of having an amplifier fail and blow their speakers is a persistent worry. After all, speakers can be rather expensive and mistakes do happen. However, any circuit added to the output of the amplifier should preserve the high quality of the output signal, which is no small feat. I designed the Guardian-86 and Guardian-686 to accomplish this goal.

The Guardian-86 is intended for use with single-ended amplifiers, including discrete designs and the many LM3886-based amplifiers.
The Guardian-686 is mainly intended for use in bridged/balanced/BTL amplifiers. The Guardian-686 can also be used in stereo and dual-mono single-ended amplifiers.

For single-ended amplifiers (where one speaker terminal is connected to ground), one Guardian-86 is needed per channel. Two Guardian-86es or one Guardian-686 for a stereo or dual-mono single-ended amp.
Bridged/balanced/BTL amplifiers (where both speaker channels are driven) need one Guardian-686 per channel.

Both circuits protect the speaker against excessive DC voltage. They also provide a turn-on delay and immediate turn-off when the supply voltage drops below a set threshold to prevent those annoying turn on/off thumps.

The key features of the Guardian-86 and Guardian-686 are:

• No relays! All switching is done with MOSFETs for the lowest distortion.
• No relay contacts to wear, thus, no change in performance due to aging.
• No impact on sound quality. No measurable impact on distortion for the Guardian-86 and only negligible impact for the Guardian-686.
• Floating photovoltaic MOSFET driver ensures consistent good performance throughout the full swing of the output signal.
• Approx. 5-second delay on power-up. Output disabled when supply voltage falls below 22 V. This dropout voltage can be further optimized for your specific application by changing one zener diode.
• Input: Molex Mega-Fit connectors and terminal blocks accepting up to AWG 10 (5.2 mm²) wire.
• Output: Terminal blocks accepting up to AWG 10 (5.2 mm²) wire and 4.2 mm diameter holes at 3/4" (19 mm) pitch for direct mounting onto the speaker output terminals.
• With the exception of two huge surface mounted MOSFETs, all components are leaded.
• Compact layout. The assembled board is approximately 1.05 inch (27 mm) in height. The Guardian-86 measures 2.50 x 1.75 inches. The Guardian-686 is a bit larger at 2.50 x 3.25 inches.
• Gold plated circuit board. Designed and manufactured in Canada. All boards are electrically tested before they leave the factory.

Some may ask, "why not use a relay?" First of all, relays are not good protection devices for protecting speakers. They tend to arc over, which often destroys both the relay and the speaker. For some rather spectacular videos of that, have a look here: Speaker DC protection with relays.
The other reason is that relays add measurable distortion, especially as they wear. MOSFETs provide much better and much more consistent performance throughout the lifetime of the MOSFET.

To read more about the Guardian-86 and purchase yours, follow this link: Guardian-86: Speaker protection board for LM3886-based amplifiers (and others).
For more information regarding the Guardian-686 and to purchase yours, click here: Guardian-686: Speaker protection board for balanced, bridged, and BTL LM3886-based amplifiers (and others).

I launched the Guardian-86 on May 31st and am almost out of boards. There are five left in the stack. I'll have more arriving in about two weeks.
I have a pretty tall stack of Guardian-686 boards in stock as it launched in the middle of July and I had more boards made.

Tom

My car has only 4”x6” holes for front speakers on the dash. So, I might only be able to install the 1” tweeters there. And for the 5.25” woofers, they would be installed on the drilled holes at the bottom and rearmost of the front doors. The question is, is the distance between tweeter and woofer matter? I know it should be matter in home audio, but I’m not sure for car audio because, in my opinion, car speakers might receive a compromised or more flexible design compared to home audio speakers.

My Ohm F's are in great condition except for a couple issues. I'd like to play them for a while as is before they need a restoration. The issue to discuss here is sagging spiders.

To correct the sag, I've read about wetting, pushing the spider to below flat (driver is upside down) and allowing it to dry, or heating it with a hair dryer, hoping that it remembers its new position.

I've also read about these spiders having bakelite varnish in them when made. Perhaps I can paint them with the same varnish, after being in the correct position, in the hope that they will be more stiff. Bakelite varnish is still available here:

https://bakelite.com/industries/coatings-inks-adhesives-sealants/coatings-and-inks/


I've also read about using a fabric stiffener such as:

Aleenes Flexible Stretchable Fabric Glue 4 fl. oz. – Aleene's
https://aleenes.com/products/aleenes-flexible-stretchable-fabric-glue-4-fl-oz
https://aleenes.com/products/aleenes-flexible-stretchable-fabric-glue-4-fl-oz
To push the spider, I'd prefer not doing this mechanically, as it may throw off the voice coil geometry. So, how about applying DC voltage to position the spider? I used a variable DC power supply on one driver to level the spider. It took 1.8V, 0.31A to get there. So I would dope with water, varnish or fabric stiffener, move the spider into position by DC voltage and wait for the dope to dry.

Any thoughts are appreciated. Again, please do not advise to replace them. I'm already aware of that option for way down the road.


1. Pics of the exterior of the drivers:
www.px625.com/ohm-f/index.html
2. Movie of exterior of driver A:
www.px625.com/ohm-f/a-outside.mp4
3. Same for driver B:
www.px625.com/ohm-f/b-outside.mp4

I finally managed to change the capacitors in this thing. I had to resort to mauling one of the clamps in order to do it. If one thing is clear, the designer never intended for this amp to be serviced.

Anyway, I fitted it with 2 new 18,000uF Nippon Chemicon caps, plus a new Cera-Mite ceramic as the original Sprague appears to be unattainable.

The amp sounds much bolder in its presentation, with fuller and more controlled bass too boot.

I have just received some pure copper banana plugs which will terminate a new set of 12 guage cables which in turn will replace the current 16 guage cables I have been using. It's damping factor should further improve.

Guys, I have a Hermes DDC and wondering what suggestions might be out there to help it achieve a higher level of SQ - if anything at all. I see a few things, some of which I am unsure will make a difference in the digital domain - WIMA MKS v. other types of capacitors. Unsure bypassing caps could or would make any difference let alone improvement - interested in thoughts here. SMD regulators, auto-sensing and switching voltage.

Hello everyone,

I was wondering if anyone knew of a source to get the Sound Practices Magazine archive on CD. Neither www.soundpractices.com nor www.southernelectricaudio.com websites function anymore and the telephone number for southern electric audio doesn't appear to be connected. Further, I did not find any other source when I did a google search. I thank you in advance for any help you can provide.

Ray

Background in analog and digital electronics, IT/OT automation security and other techy things. I've designed and built my share of subwoofers and loudspeakers since the 80's, built various amplifier kits and have a great love for audio in general. Always looking to glean and share knowledge in this area.

Hello colleagues!

I'm Alex from Ukraine, and registered on the forum to share my thoughts, learn something new for myself and have constructive communication with people who are passionate about electronics.
My interests:

• transistor amplifiers
• RIAA preamp
• MC12 and everything related on circuit design.

Sincerely

Hi everyone, I know there's an old thread on this but I will be converting a pair of BM6A into passive speakers and I want to reopen the topic. Much appreciated for the drawn schematic of the BM6 crossover in the previous thread.

I got a pair of BM6A, both MK1 but different revisions. Their amps are blown and butchered for parts. Fixing the amps will be more of a long-term thing. My idea is to make the speakers passive and experiment with filling the empty amp cavities with sand as they are insulated from the speaker drivers. Some sort of mass loading, I suppose, to replace the missing mass from the amps.

I’m a huge fan of Dynaudio. I own a pair of BM15A, BM5 MK1, Audience 70 and now these BM6A. All from a similar age (late 90s, early 00s). Out of curiosity I tried using the BM5 crossovers (2.7kHz) in the BM6A and their low-end was very poor. I was surprised because they both use visually identical woofers, 28mm soft dome tweeters from the same era, and similar internal cabinet volume. I figured it wouldn’t hurt to try.

Anyway, I hope the schematic suggested here will work fine. My assumption to why the passive BA6 crosses at 3.1kHz and not at 2.2kHz like the active version is that the latter has steeper slopes (4th order?). I suppose that would require more components in the signal path of a passive speaker, it would be pricier to manufacture, and harder to make accurate. Am I wrong? Can anyone suggest a crossover schematic at 2.2kHz and if not - are there any specific reason why it should be kept at 3.1kHz?

Hello, i'am Mirko from Germany and i often read the interesting themes here in this Forum. I hope we will have many good discussions.

Hello. I have been a member for a few years and am only just now interested in some opinions regarding my amp. I am currently running a Rotel RB 1095 and have an RB 1090 out of comission due to A faulty power switch that sticks and I am unable to at times either power up or power down. I have A Rotel RC 1082 preamp. Dynaudio Contour 3.4s with upgraded tweeters from Esotec to Esotar 2. Read where quite A few had made this change with great results. No tweak to the crossovers necessary. I use A Blusound Node to stream with roon, A Rotel RCD 1072 CD player, Technics 1200mk 2 turntable with an AT VM95ml cartridge, Denon 3500H that I run preouts for movies occasionally. Center is A Dynaudio Contour SC and matches the mains. Will be shortly putting an Esotar tweeter into that as well. So nothing ourageous compared to some but it is meeting my needs and still puts A smile on my face when I turn it on. All purchased second hand and has been great for approximately 4 years. The only new piece purchased is the Blusound. Other than that I am not sure how these intro's work. I am married with two kids 35 and 33, RN for over 25 years, moved from Home territory in the suburbs of NY to Mesa Az in 2000. This is not the time of year to be here, 112f today.

Hello audio friends,
I am an electrical engineer and tube novice from Miami, Florida. I graduate this fall from FIU for electrical engineering and am trying to learn as much as I can about audio as I am an audiophile. I look forward to learning from all of you!

Moderation edit:
This account has been banned for the breaking of forum rules. This post remains only as a placeholder for the thread.