Hi, long time lurker of this forum! I have built full range speakers for home office desktop and tv, and i would like now to build a 2 way speaker.

I've often wondered if there is a way to model the cavity resonance that tends to affect the response of folded open baffle woofers, such as H-frames, and perhaps U-frames and even ripoles. I've looked for info on diyaudio from time to time, but until recently had never picked up anything very useful. I have tried Hornresp, but found it limited to a few specific geometries. (Maybe that's just a reflection of my small experience with it.)

My (poor) knowledge of open baffle theory has mostly come from reading Linkwitz Lab, and I have a vague memory of Siegfried suggesting that it's the length (front to back) of a cavity that is the primary determinant of cavity resonances. But I was pretty sure I'd also read a comment from him to the effect that measured results didn't match theory very well. (Which doesn't bode well for modelling.)

Anyway, I went back to the Linkwitz Lab site and, sure enough, found this page: https://www.linkwitzlab.com/models.htm#C
Siegfried said, there: "If you build an H baffle woofer ... there will also be a response peak due to a l/4 resonance of the waveguides in front and behind the drivers."

He then shows a nearfield response measurement of his Phoenix woofer baffle (a W-frame, actually) showing just such a peak:



He comments: "The PHOENIX woofer has D=19" (0.48 m) separation between its openings. The peak should be at f = 0.5*v/D = 357 Hz, but the cabinet layout is too complicated for such simple calculation to apply exactly."

This is what I read years ago. Going back to it, though, had me really scratching my head. The peak is nowhere near 357Hz, but also, I don't actually understand why SL said initially it's a l/4 resonance, (which is what you'd expect for a pipe open at one end) but then calculated the expected frequency as l/2.

So I was no further forward.

Recently, however, I stumbled across an old thread here on diyaudio which addresses the very question of cavity resonance:
https://www.diyaudio.com/community/threads/ripole-cavity-resonance-question.240193/
This got my hopes up. I was particularly pleased when saw that an answer to the question of how to calculate cavity resonance was offered by @bolserst. This is a key part of what he had to say:

"The cavity resonance is ... a Helmholtz type resonance which develops because the air inside the cavity acts like a spring and the air at the opening of the cavity acts like a mass. You can think of it as a vented or ported box with port length zero and port area the size of the opening. With this in mind, you can get an estimate of what the cavity resonance would be by using a calculator for a vented box. Just set the volume of the box equal to the volume of the cavity, and the area of the port equal to the area of the cavity opening. Then solve for the tuning frequency that gets you a port length of zero."

He also comments that quarter-wave theory only begins to apply when the cavity geometry is more pipe-like. It struck me immediately that this is a much more promising way of thinking about cavity resonances.

The next thing I realised was that there is an easy way for me to model them, because I'm familiar with how to model vented boxes in Basta! So, I fired up Basta! and had a go, and the results are very encouraging. The method I've settled on is actually not to model a cavity as a simple vented box. (Although you can if you like. However you'll get a rather 'busy' graph from that, with driver and vent responses, and a combined response that rolls off the low frequencies, but doesn't reflect the baffle dimensions.) A better way is actually to model a bandpass box with a single vent, and with the volume of the rear enclosure set very large. Like this:



In this model, the driver behaviour is not constrained by the rear box volume, because Vb2 is set so large. The response curve you get is the response of the vent. You set Vb to your best estimate of the volume of the cavity, and then in the Vent/PR tab, you set the vent cross-sectional area to match the area you calculate for the cavity mouth. Then adjust the vent tuning frequency until the vent length is approximately zero.

I did this for the Phoenix woofer box (with a fair bit of guess-work) and got the response shown above. As you can see, it's not a bad match for Siegried's measured response. (There is actually a slight broadening of the resonance, because the Phoenix W-baffle dimensions generate slightly different resonances front and back. Siegfied's measurements show even more of a broadening in the resonance than my model did.) Note that the modelled response does not take account of the rear driver radiation, and therefore doesn't show the dipole roll-off at low frequencies. But Siegfried's measured response was near-field, so it doesn't show the dipole roll-off either. (You can model the dipole roll-off in Basta! by selecting "Baffle" as the enclosure type. You just can't model the roll-off and the cavity resonance at the same time.)

So, anyway, I'm extremely grateful to bolserst for getting me thinking more clearly about cavity resonances. And I can recommend Basta! as a simple way to generate a rough model. I'm hopeful it's reasonably accurate. When I get some time I'll do a few measurements of my own and see how well they match the modelling.

Generally regarded as the most advanced preamp of its day. (1973 on)

But who designed it? Anyone know?

On a couple of threads I have promised to post the schematic for my latest (and best) version of my EL84 Ultralinear Amp. This design is based upon an ECL86 Amp design posted by Yves quite some time ago. This design uses shunt feedback to reduce the output stage rp and thus better drive the limited primary inductance of cheaper output transformers. Regardless of that, the result is good enough that its worth using reasonable quality transformers and while the common Hammond 1608 (Raa = 8K) will work well, it really deserves something a bit higher quality (more expensive). It can be used without the Ultralinear connection BUT performance would be degraded.

It UNASHAMEDLY uses Solid State to assist the tubes toward their maximum performance.

I believe it is suitable as a "newbies" first project and it will certainly out-perform most of the simple "suitable for newbies" designs I have seen here and elsewhere.

I'm off the air for the next 5 days BUT feel free to discuss, criticise etc.

Having said that some component choices were what I had in my parts bins.

Components:
All the 0.22uF/400V are Wima FKP1 - I just bought a batch of them
The volume pot could be 50K log or 100K log rather than the 220K.
The MJE340s in the bias blocks don't need heatsinks if mounted against the chassis (they dissipate about 1/2 a watt) else a small heatsink would be advisable.

Adjustments:
Set the BAL.(ance) pot for equal anode voltages at pins 1 and 6 of the ECC803S (premium 12AX7)
The 16K resistor between the 47Ks from the EL84 Anodes sets the shunt feedback level. Too much and the input stage will clip and output power will reduce.
The 12K and 470R network in the grid circuit (pin 1 of ECC803S) set the global feedback. I've used minimal global feedback.

Hope yopu like it!!!

Cheers,
Ian

I don't know how they made WinISD, but I'm aware that it may be possible that using it to simulate designs far enough outside the norm, it could calculate things wrong, if normally insignificant parameters become significant but aren't included in whatever formulas it uses. Kind of like how I can't believe port dimensions are not considered in the SPL graph.

I'm playing around with what happens if weight is added to the driver, and wanted to try to find how the resonance frequency changes, to better understand what's going on. It doesn't always make sense, and I recently found something that really didn't make sense.

Using the impedance graph to judge the resonance frequency in a closed box, adding drivers raises the resonance according to the peak impedance, but if weight is added to the drivers, then adding drivers decreases the resonance. Well, not exactly. Checking it again, I was able to find conditions such that adding weight to 1 driver lowered FS, 2 drivers increased it slightly, then 3 or more drivers decreased it.

It's a faulty formula, right?

I doubt if this can ever be resolved. I had a S500 that had the same noise. Now I have a s550e which sounds amazing but has a slight buzz through speakers when idling just like the S500 had. NOTHING I do gets rid of it. Lifted gnd on power cord. Removed input cables. Switched to balanced input. Can’t hear when playing music but bothers me to hear noise. It was dead silent until the rectifiers were updated and bias pots replaced and adjusted. This must be common in these amps. I’ve read other posts on this. Has anyone ever resolved it?

Hi,

Posted in Swap Meet forum, but may get a better/faster response from the source.
Would like to buy or have PCBs made for the Sony VFET amp, preferably the N-Ch version. Push-pull version OK as well.
If gerber files are available, please share or let me know where I can find them. Thanks!

Vince

This is the Millett Hybrid amp but with Edcor OPTs. You can read about it on his site.
The chassis is steel and rift sawn Sapele.
I am asking $450 (plus shipping), which is basically the cost of parts. I would prefer to sell locally, if possible but I am located in Santa Fe New Mexico, so that might not work out. If you are interested but would require shipping in the US, feel free to message me.

Cheers,

Hi everyone. I'm finally joining this community which I've learnt a lot from, but I've a few questions that I'm itching to find good answers.
The topic? Powered BMR monitor speakers with a three-way active crossover.

Tweeter: Raal 64-10 (crossed LR4 3400Hz)
Midrange: Tectonic TEBM46C20N-4B BMR 3" (crossed LR4 400Hz)
Woofer: Dayton Epique 180HE-44 7" in a passive radiator sealed box.

Background: I'm really a big fan of Mr. Dennis Murphy's work and wanted to emulate the philharmonic BMR monitors. The extremely wide horizontal dispersion granted by the BMR midrange and raal ribbon is something very appealing and different from any other three way speaker design and made me want to emulate his design. On the way, why not make it an active speaker? Getting past complex passive crossovers means that the amp will see a simple load&reduce back-emf, lower IMD, reduce power loss, and I don't need to deal with crossover complexities. The Xkits active crossover modules are LR4, and the flat performance of the BMR and 64-10 are perfect together.
As for choice of woofer, why these? Why not? Given enough power, these produce decent bass for a 7inch woofer, and measure decently while being compact. And PRs simplify things a lot. For amplification, I'm using two class AB amps for the midrange and tweeter, and class D for bass, but discussion about these will be limited here to focus on the questions.

So my questions are:
1) Given that a rounded side baffle can improve horizontal radiation, is there such a thing as too much rounding? As I know, a more sudden curve can affect longer frequencies more than shorter ones, and so negatively impact horizontal radiation. If this is the case, a more flat baffle might be appropriate.
- There is a simulation for rounded baffles giving very smooth horizontal radiation.
https://www.audiosciencereview.com/.../philharmonic-bmr-speaker-review.14781/page-5

2) Should I stay with the three way WMT design or go for WMTM?
- As much as I love Mr Dennis's BMR monitor design, I'm really tempted to try out his BMR tower design with WMTM using the same BMR and ribbon
- https://philharmonicaudio.com/products/bmr-tower
- Why MTM?
- a single 3" midrange may benefit from an extra one to allow higher SPL capability, lower distortion, and more controlled (albeit narrower) vertical dispersion
- use of a ribbon means a narrow vertical dispersion anyway
- but there's reason for not needing an extra bmr: https://www.erinsaudiocorner.com/loudspeakers/philharmonic_bmr_v2/
- a single BMR exhibits low HD and performs well in the compression test
- A WMTM will look glorious (99% this is the reason). Really, why not? Just go for it?

Thank you, and appreciate any input regarding this.

This regulator is straight forward.
Uses the OPA1655 to control 3 transistors.
It is a low drop-out regulator.
In my image you can see an example for 20.30V in and 20.00V out at load 2.5A.

I have simulated to see the PSRR.
At 100Hz it is better than 121dB. At 1kHz it is better than 93dB.
The PSRR is mainly determined by the Opamp OPA1655.

The regulator is adjustable from 10V out to 30V out.
Of course this is limited by the max supply to the opamp: 40V.

Hi All

Thought i would post my amp build.

I liked the simplicity of how everything went together.

Only thing needing adjusting was the DC offset (I've drilled a whole in the heatsink inline with the potentiometer so you can easily adjust it)

All in all a fun built and a great sounding amp.

Kept all cables neat and tidy with short runs.

The amp modules are elevated and the heatsinks were modified from an old project to fit.

Hi,

i am looking for a high quality full range driver for a diy cabinet (appreciate if there is already a plans) to match with my 300b amplifier.
My 300b is a type which churns out around 11 Watts single ended Class A.
(monoblocks made by Diyhifisuply, the Lux mono max)

I am looking for quality.
Price is an issue as always, say around the 300-350€ per driver max if possible.

My listening room is 3.5x4 meter, so small room.
I listen mostly to jazz, electronic, indie, rock, classical.

Thanks for your help!

Each track used 2 to 3 will SA1186 2 SC2837 2.

LAPT power transistors, ultra-high frequency FT, solve the CFP switch distortion.

Tiny hand in the distortion + 0.6 V.

I have decided to try to sell some of my first DIY projects.
This is the Millett Engineer's Amp. If you don't know it, read about it on his site.
The chassis is hand made from steel and "thermory" Ash (Kiln treated Ash).
The Iron is from Edcor, I just like to re-patina the covers.
I am asking $450 (plus shipping), which is basically the cost of parts. I would prefer to sell locally, if possible but I am located in Santa Fe New Mexico, so that might not work out. If you are interested but would require shipping in the US, feel free to message me.

Cheers,

Hi everyone,
This project turned out to be quick, straightforward, and with a great outcome—so I figured it was worth sharing.

These desktop speakers deliver a clean, confident sound. They handle plenty of power, are solidly built, and easy to put together. The goal was to upgrade the speakers I use with my PC (driven by a TPA3116 amp) for listening to music, voice, and video—so clarity was key. That said, with a bit of EQ, they’re also more than capable of livening up a party.

I went with Faital drivers, partly because they’re readily available here in Buenos Aires, but also because they come with reliable and comprehensive specs.

I kept the crossover design simple—a first-order Butterworth filter set at 1kHz—and it did the trick. Of course, you can always tweak the resistor values if you want to shape the top end a bit more.

The Micro-Audio SMPS600-R2 is a high-quality, unregulated 600W switching power supply designed for audio applications. It offers a single-rail output of 46Vdc. SMPS was bought few months ago and it is in perfect working condition. Dimensions are 187x123x50 mm and weight is around 800g.

This SMPS is designed to power various TPA3255 amplifiers, like 3e modules and others. It provides significant sonic upgrade, compare to cheap SMPS.

I paid around 200 EUR (all shipping costs and custom fees included) to import it to Slovenia (EU). My price is 150 EUR + PayPal fee. This price already includes shipping (with tracking) to EU countries. For additional fee, I could ship worldwide.

I have for sale a set of two additional capacitor boards. They were designed to improve performance of single rail SMPS when powering D class amplifiers (3e, Sylph Audio...). Dimensions of the board are 95x50x40(height with spacers) mm. Each pcb board consist of:

1x Nichicon FW 1000uF 63V
2x Nichicon FW 470uF 100V
1x Nichicon KZ 100uF 100V
1x Mundorf 1uF 250V foil capacitor


Price is 35 EUR (for set of 2) + post costs + PP fee

http://www.hostboard.com/cgi-bin/ultimatebb.cgi/ubb/get_topic/f/3729/t/3273

Greets!

Averaged specs used:

Fs' 28.84
Qts' 0.307
Qms' 4.614
Qes' 0.329
Vas' (L) 473.024
Re' 6.442
Le' 1.295
Sd' 856.336
BL' 15.383
Sens' 97.24
Znom' 8

Being fond of the 800 series cab's baffle proportions, an 81" long folded pipe looks good with internal dims of 40.5" H x 28.5" W x 18.75" D including 3/4" divider, so just a hair over the 12 ft^3 limit with external dims of 42" W x 30" W x 20.25" D. Driver down from top front 8.5" and 6" dia. (or other shape = 28.274"^2) x 2" vent on the rear up 17.56" from the bottom for a ~27 Hz Fb.

GM

Looking for a first tube(valve) amplifier to see what the hype is all about. I currently run a Lesboxed Yaqin Pre on my turntable and would like to try a tube amp for the speakers too. I'm in the UK and am not looking to spend huge amounts.

I'm looking to build an Aleph Mini, currently trying to gather parts to order, for now I have found:

https://www.ebay.co.uk/itm/266392011176?mkevt=1&mkcid=1&mkrid=710-53481-19255-0 - the pcb
https://www.ebay.com/itm/156560013829 - mosfets
alternatively, but I'm not sure if it'd be best - https://www.ebay.com/itm/115126018088?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=wGG0QMocRHa

https://a.aliexpress.com/_EIU0SPC - enclosure

I'm also not quite sure about the PSU, what board / transformer should I use, and how to wire the potentiometer.

Hello, I'm trying to replicate the simulation of Richard Lee's MC head amp from this document:
https://hifisonix.com/wp-content/uploads/2019/06/Richard-Lees-Ultra-MC-Amp.pdf
The simulated circuit uses 2sb737 and 2sd786 transistors but i can't seem to find the device models anywhere. Any help locating them would be greatly appreciated.

Hi, all.

Would - instead of implementing a soft start circuit - the habitual use of a Variac with slow manual ramp up of mains voltage to nominal
over f ex 30 seconds have any detrimental effects on the tubes of a tube power amplifier ?

thank you,
FrankieS

Hello,
After using K2 on the potentiometers that were spluttering, I was unpleasantly surprised to see the amp go into safety mode after reassembly.
I checked the supply voltages and found:
+14V at the output of Q13 (LM317) and -14V on Q12 (LM337) for +/-15V ===> correct.
However, I'm reading +25V instead of 32V on R4 and -28V instead of -35V on R7.
R4 and R7 are fuses, and their checked value is consistent with the schematic.
If I disconnect the preamp, I find +60V and -60V across R4 and R7.
I think the problem is with the preamp, but I don't know how to investigate the fault. Any ideas welcome...
Thank you for your help.

Today I bought 🙂 (pics are not mine)

Harman Kardon Citation 11


Yamaha B-2


Nakamichi 480


Philips CD-104


Yamaha CT-610


Philips CDR-765


CEC DD-8200 with Shure V15 type IV


Grundig Fine Arts T-903 MKII


Next 😀

Oops! Almost forgot yesterdays goodie 🙂

In the last few days off, I have been somewhat confused and have tried to collect enough reasonable data for a possible replacement circuit using the usual home remedies. I don't know whether I succeeded or whether I was able to develop a common thread; the more diagrams one plot, the more confused the scenario becomes. I deliberately left out the interesting mechanical side, because how can one approach it reasonably well with home remedies? Of course one can think about the elastic side between the cantilever and tip and the plastic disk, but on average we always come to a conclusion, reso fo is always less than 35kHz and the cutoff fc moves from 61kHz to 32kHz ... outside to inside.

Perhaps we can develop a test procedure, a common thread, together at this point.

Hello guys, working on a vintage Carver TFM 55 amplifier with a defective 2SC3281 output transistor. These apparently have been obsolete for some time now. Does anyone have a suggestion for a suitable replacement transistor? Thank you in advance for any help.

What is the purpose of adding these components to the original circuit.
I have the same amp so should I do the same if this improves the output?
Also I would need to know the components as well.

Hello

I open these thread for these all Hitachi Lateral & Jfet amplifier.
Here is the circuit & website.
A Paul Kemble web page - Hitachi Fet designs.
Now for these amplifier the mosfets are still available but the JFet must be replaced because they are no longer on the market.
We started a conversation about these amp on the Naim 140 clon from Ebay thread.
We think it is time to keep that threat to Naim clone and open a new for these.
AndrewT advised to dedicate these amp to Borbely...He was famous using fets in his own high-end amplifiers etc.
There is two amplifier circuit. You all welcome if you interested to comment, redesign etc these amplifier.
To the all Hitachi fet I have all the mosfets at hand just need the JFet.
I really would like to give a try (at least test these amp)but not without modifying the front end since those JFet are past now.

Greetings Gabor🙂

Hi all.
I have recently got my hands on an NAD 705.
It had a backlight issue which I fixed in no time.
But now I notice the display is fading after about 1 second and it's also jittery (some segments sometimes appear randomly?)
Has anyone ever came across this failure?
Is it the LCD itself?
Can it be the LCD Driver? (Sanyo LC7582)

Please help... 🙏

Finally, Plethora of Pinjatas, origin of P series of amps

These (P) being more or less derivatives of my recent M2 derivatives ........and you know them , so no need to go in detail

So, active FE instead of buffer+autoformer FE; biasing mech. being more or less same (current sense in rails), only - with help of current mirrors, being sorta flipped upside down, vs. previous optocoupler based one

even if optocoupler based biasing is more than good, believe me, this one is even better ...... in anything you can remember to ask about

Iq and Offset stability is bespoke, in any domain I can think of - time, temperature, rails change ( mains fluctuation), no even slightest pops during Power On and Power Off

everything to embrace Square Law OS

(aha, this one being origin, even if its bigger brother - Babelfish XA252 been made first)

OK, straight MOS being real Plethora of Pinjatas ....... (is it Mini Babelfish XA252?)

SET P being then same pcb with twist - upper mosfet in Schade arrangement (is it Mini Babelfish XA252 SET ?)

pretty close to point where I can't even follow my self, go figure

'nuff babbling, some usual pics

schm is cumulative; down will post separate ones

Can one reliably hear any difference between this amplifier and a lower THD amplifier. A really good amplifier. As you can see no capacitor is used for stability compensation
https://www.pcbway.com/project/shareproject/mosfet_amplifier_f17685a0.html

The SYMEF amplifier has moved here.
SYMEF Type S



SYMEF T2 Schematic


Schematic link for V 2024: https://www.pcbway.com/project/shareproject/SYMEF_Audio_Power_Amplifier_8bb70aa8.html
SYMEF Ensemble https://www.pcbway.com/project/shareproject/SYMEF_Ensemble_audio_power_amplifier_bf5439e4.html

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USER FEEDBACK

1. ... Extreme grip on the woofers....... Yes I almost fainted when i played Lee Ritenour as the first note. .... I felt the bass note right in my guts.....It is natural since this amp plays ridiculously good and I would like to be able to use it with my setup..... Have been playing with the amp some hours now. The initial harshness in the upper regions seems gone. Suspect some burn-in time. Only beautiful music. ......... I have tried alot of amplifiers during my HIFI - time. This is maybe the first transistor amp I have tested that really grips the woofers and are very dynamic at very low volumes.......... Vocals seem 'real' and I have not tried any classical yet................ Symef just keeps impressing me.. I have a hard time saying this but my tube power amp may get early retirement........
2. First contributor to trying out the SYMEF design. In listening test, surely it has beaten my carver receiver. I have used a behringer mixer with low ,mid and high control and to control the volume of the signal because I did not put a volume control on the amp. I compare the symef to my carver coz it has also high ,mid and low control. symef turned my tower speaker(Yamaha) sounds like a big speaker. Voice of the artist sounds big and the bass is very good even at low volume. I really like the mids and lows of this amp. That's why its sounds very natural to me. thank you so much for this amplifier. I am very satisfied with this amp. It is really worth of my money, time and energy. Now my worries are over the amp. is working and sound is excellent.
3. I received a positive listening experience with SYMEF in the entire tonal range. But it was particularly the tremble that attracted my greatest attention, and I wanted to investigate this further. On my 'main' equipment I play my CDs from a Sinology NAS to a Aspirator Transporter(with Squeezebox Duet). The rest: A strongly modified DCX 2496 (Janneman) takes care of the crossover and equalizing. The three final amplifiers are: NAD 208 for two subs and two Goldmund Mimesis clones(3 and 9) for the rest of the range. Speakers are Magnepan 1.6 and NHT 1259. This equipment, I feel, is of high quality and have so far met my needs and my perception of what constitutes good HIFI. To get an impression, I did the following: I played a number of discs 'in parallel' (on the same time) from 1).My main equipment, and from 2).My Copland 288 connected to SYMEF. I could switch between these two possibilities(they were synchronized to always be on the same place on the CD), or let them play simultaneously. This way, I could confirm that there really were differences in the reproduction of high frequencies. The next move was the following: I disconnected the Goldmund 3 from my main equipment. Then I connected SYMEF, which I have calibrated so that I would not 'let me fall' for the amplifier that delivers the most powerful output signal to be the 'best'. The differences between SYMEF and Goldmund 3 were confirmed. I have been sitting all night and played through my countless discs: OnAudio congratulations 'We have winner.' I have so far been very pleased with how my main system has played almost every music genres. I say almost, as I have, playing classical music, had a small complaint: I generally have a large, wide and deep sound stage when I play other kinds of music. I do not experience the same degree been present when I play classical music. My Goldmund 3 has also had a touch of 'rawness' in the upper treble that has always annoyed me a bit. Violins and cellos now have more air around them, becomes cleaner. More clarity in the overall sound. My impression is that the entire orchestra 'growing' = being bigger.
4. Its a very enjoyable amplifier with a lively presentation. The mids are lust, particularly with female voices euphoric that easily seduces. The bass is present with great control and is very well-defined. The highs are rich and detailed (you can hear the little details and articulation of the voices).
5. This is a very good amplifier! Indeed, the formula works.
6. Very nice! Everything went up smoothly at power-on, excellent sound stage very similar to my Leach build but with a heavier bass punch. Pretty silent to no turn on and off thump and with all that messy wiring during test, hum problem did not occur I currently amplifier Symef of Pinnocchio. It is connected with a tube preamp Conrad, with the source files loss - less 16 - bit and 24 - bit.The speakers are my design, Tubassons Mark 2(3 ways, 2 x woofer SB17, mid SB12, tweeter SC6620). I listen for at least a few weeks. This is one of the best amp I 've heard. My regular amplifier is a Goldmund Mimesis 29 clones that Pinnochio assembled (MOS FET 5 w Class A, 85 w / c 8 ohms). In comparison, a Symef as transparent or nearly at the top of the spectrum. I am very surprised. But it is in the lower register and the lower mid range that Symef is definitely higher. I listen to jazz, classical, folk and rock.The bass is not only powerful, but it is very precise and articulate. The lower mid range is excellent and allows us to appreciate the voices of men as well as women. Whether it 's a live or studio recording, the music that comes out of this amp is highly musical, and this with minimal coloration. The icing on the cake is the realism of the sound image, as with classical and Jazz very powerful. Whatever the volume, the image is stable and the instruments are very well spaced.The image is 3 d.The sound stage is realistic and very close to a single - ended tube amplifier. This with power and ease way to reproduce very detailed very complex musical messages. I still can not believe it.
7. There is no hint of any oscillation, bias is quite stable, and vbe multiplier is quite responsive to heat sink temperature. Probably need to adjust the bias after it reached steady state. Measured 1 kHz and 10 kHz square wave and 10 kHz sine wave response, its clean and rounded edges on square waves. Played through my home made bookshelf speakers. In one word, the sound is marvelous. Although I have to do an extensive listening, the amp just displays its character in the first song itself. Sound stage is huge, vocals are accurate and highs are detailed. Overall the sound is very balanced in the whole audio range, no slamming bass or shrill voice. Its just perfect;you don 't want to stop listening. I am not comparing this amp in isolation. I 've already built SymAsym, and F5 also I have coupled Lux man amps, so I have some very good amps for reference. Having said that, this is a very good sounding amp with huge sound stage and openness. I don 't know what your magic formula is, but it is wonderful. I cannot stop listening to this amp.
8. It cannot be explained with words, it have to be listened to in real life.
9. Further listening with the amp I, m more and more impressed with the ease in which it can take you into another world. I can, t wait to build the other channel and use better parts, to bring out this best this amp can do.
10. A lot of great designers in this world that will make us confused. Finally, I decided to assemble this amp. Thank you, Sir for the support. Only with a potluck part, the SYMEF is really different. Yes....this amp is unbelievable. Very easy adapted according to our tastes. Very convenient be heard(of all kinds of music), The bass is more than power full, Very clear articulations, the high is very crisp and smooth. With the MP3 format(196 kbps) even no less with the FLAC. Maybe you won't believe it, but this is the reality. Sorry for my bad English Thank you, Sir, you make my life happier
11. The sound is very transparent. It brings out the best of recordings specially of female vocals. I compared it to my AV receiver, and I am impressed with the sound. It seems more natural and the music is more alive. With no input signal, there is no hum or hiss with my ears directly on the tweeters! I used a 500w SMPS with additional 20kuF capacitors, and I am very happy with it. The amp is completely silent.
12. Very nice! Everything went up smoothly at power-on, excellent sound stage very similar to my Leach build but with a heavier bass punch. Pretty silent to no turn on and off thump and with all that messy wiring during test, hum problem did not occur Thank you sir Harrison

I am attempting to determine whether the C7 is an IRS20957S. If it is not, please inform me. If you have this information, I would appreciate your assistance.

Thank you.

Hello everyone,
I have for sale pair of DIY finished boards of B&K st 140 amplifier built on the original exactly schematics.
Construction with components of absolute audio quality and definitely superior to the original:

• Nichicon Fine Gold audio capacitors
• Nichicon MUSE audio on the signal path (green)
• MKP bypass capacitors (Polypropylene)
• Cornell Dubilier silver mica capacitors
• ORIGINAL HITACHI K135 and J50 final MOSFETS
• Construction with Cardas tin.

Calibration as service manual 200ma @ 20kHz and zero DC offset (see photo) and absolutely perfect measurements in terms of bias, DC offset and THD (see measurements).
Power supply required dual 60V DC to have the nominal power of 105Watt/channel on 8 ohms.
Sound very well and powerful with NO hum and perfectly stable in temperature and elecrtical parameters.
Big heat sinks is not included.
Price request 80 Euro plus shipping (From ITALY).
Consider that the Hitachi mosfets alone are worth the asking price.
Some pics:

I decided to create a desktop system and planned on repurposing a pair of mini monitors from an Energy Take 5.1 home theater setup. I connected the speakers and the sound was thin on one side; a bias to the other side. It turns out that there was no sound coming from the woofer on the thin side.

My first step was to physically switch the speakers, though I felt that if sound was produced by the tweeter that it was unlikely that there was an issue further up the chain. Once switched the thinness moved to the other side, so it was the speaker. I pulled the front baffle off to see if the wires were connected to the woofer and they were. I saw the crossover, but I didn't really investigate further, as I didn't know what I was looking for. The other two mini monitors from the set are dead and gone, otherwise I'd just replace the bad one with one of those.

I have already ordered another pair of speakers, but I would still like to fix the speaker if possible. I think it would be a good learning experience for an electronics newbie. Given that I have narrowed the problem to inside the speaker cabinet, how do I go about troubleshooting the issue?

Thank you.

I last repaired one of my 8 track tapes 🙂

I got volume 2 of "1950s rock and roll collection" and the pad was no good so I went out to find a good pad...... I found one and last night I went about fixing it....

When I opened the cartridge the tape came off the spool a little and I thought I lost the tape but I managed to get it wound back on the spool and into the cartridge and she plays fine 🙂

Now to get volume 3 of this amazing set.... Its a 4 record set,3 8 track set (Im not sure how many cassettes or CDs in the set)

Looking to find a source to order some replacements for these or if anyone knows of something more readily available that would be interchangeable. The legs snapped off from vibration damage.

Thanks!

I have been rebuilding a pair of Quad ESL-63s and am getting close to finishing. By rebuild, I mean I have reglued stators, and replaced diaphragms in all eight drivers.

I used Gorilla clear polyurethane glue to glue the stators of only one speaker- the other stators were bonded well and would probably have broken if I tried to break them loose.

I used 3 um mylar film, stretched using a pneumatic stretcher, with resonance tuned while the film was on the stretcher to about 92Hz. The diaphragms are glued using 4693H contact cement that unlike the factory glue, actually bonds to the grid and the diaphragm.

I applied Licron Crystal to the diaphragms and tested resistivity and resonance before and after applying the Licron. Resistivities all came out at either 10^8 or 10^9 Ohms/square. Resonance dropped by about 1 Hz with the added mass of the Licron Crystal. For those who might be concerned about longevity, I have some old drivers that I worked on in the early 90s that used 4693H and Licron coating, and they are still in good shape.







You can see details of my failed and successful methods on my blog page, here.

I'll be installing the drivers back into the speakers and testing with full bias applied over the next couple days.

Dear all,
more for experimenting than of any practical value I would like to ask
this nice community for inputs & opinions on two related, highly theoretical projects,
the first one realistic, the second one utopia. I asked ChatGPT a bit for answers, but I'm not sure
how accurate the information gained is.

Project #1 (software):
Task: Retrieve digital audio samples of very high quality.
Split the audio range (20 Hz - 20000 Hz) of these samples into non-overlapping, logarithmically spaced bands of a variable number "n".
"n" variable for experimenting, f.ex. n = 1 up to 1000.
Measure total amplitude of every single band and apply this amplitude to a sinus wave of each
band's center frequency. Add all these new sinus waves together again to receive a summed signal which is a 'reduction'
of the source's audio signal (Fourier etc.).
Base Questions: How many bands "n" at a minimum are necessary to understand voice signals again from this source signal reduction
& resynthesis ? And how many at a minimum for 'rather' uncompromised audio quality ?
(Interestingly modern cochlear implants (of course no HiFi quality) use the very low number of 8 - 22 different frequency bands,
that are overlapping, however, and thus correspond possibly to 6 - 12 different bands only, effectively !)

Which software(s) then could do this job for sample source signals efficiently and accurately, but not necessarily in real time ?
(the problem is of course more complex, because not only amplitudes but also the phases of the signals also are important
across these manipulations).

Project #2 (practical utopia):
To build a loudspeaker with a large multitude of single low cost chassis.
Each chassis emits only one single fixed frequency, and each is triggered by an upstream
(cheap & as small as possible) amplifier that receives modulating input only from single sinus waves
(from Project #1).
Question: What is the minimum number "n" of chassis with logarithmically spaced fixed sinus signals
to recover 'rather' optimum audio quality (20, or 40, or 200, or 1000) ?

thank you kindly for any input & critique,
good night,
FrankieS

Here I described how to remove a dustcap

https://www.diyaudio.com/community/threads/how-to-remove-a-dustcap.397165/

Now I show an easy way to make a metal whizzer cone or double cone

For a flatter double cone cut one tart alike piece out of an eigth of the round aluminium foil.

For a more steep cut out one fourth of it or more.

The diaphragm is made out of thick aluminum often found for packing coffee

The diaphragm does not look "nice" but is functional. And has a "fuzzy logic" structure. The more it has wrinkles the more it is stable.

As the cone is glued together it has also some damping.

I've come up with an unusual amplifier topology involving boostrapped stuff, and that seems to have, shall we say... non-optimal clipping behavior. So it looks like I'm going to need a pre-clipping circuit.

Of course it should not distort at all until it does.

I've sketched a number of attempts, all involving bootstrapping the clipper diodes to reduce distortion by keeping voltage across them constant, which avoids nonlinear capacitance effects, leakage, etc. The bootstrap voltage is itself clipped by another pair of diodes, so when it reaches the limit, the other side of the diodes no longer follows the input signal and they begin doing their job.

The four ones on the left use diodes or transistors as diodes. They're strictly at the input of the amp, so they need an opamp buffer for the bootstrap voltage. The one on the right deletes the opamp by using the amp's output voltage (the power amp is VCVS E1) and using BJT emitter followers as diodes. Basically the two transistors' bases follow the input signal so they do nothing, until the diodes on the right conduct, at which point the transistors limit the input signal.

On the left is a sinewave with a smashed top.



And here is THD vs input level. Simulations are sometimes slightly optimistic, but it looks like "no distortion before it has to begin clipping" is achievable.



Thoughts?

Back in 2010 i hired Bob Brines to help me with simulation of a MLTL. Many enthusiast in Norway made this construction back then.

This winter (2024-25) I got help from Seas to simulate and measure in the anechoic chamber. IMO their correction filter is very very good.

Here is the driver unit:

https://www.seas.no/index.php?optio...a22rcz&catid=53:prestige-fullrange&Itemid=466

PS! This is only for private use, not commercial!

This is the place to post known good spice models, and links to libraries, and/or library files. This should help to make good spice models more generally accessible to the membership. General discussion of modeling and measurement issues welcome.

Hi all.

Thank you for approving my request to join. My name is Aristo. I am from sunny South Africa.

I had my Pioneer amplifier, VSA-701S, now for 4 years. I need some help with a setting please. I want to change the display color from the yellow/orange to white/light blue. I saw on youtube most of them is the blueish color.

Can someone please help me to change it. I also do not have a user manual.

I will really appreciate it.

Best of regards.

Hi,

I am quoting Zaph audio driver size and port recommendations.

"8 to 10" woofers will use a 2" flared port. 12 to 15" will use a 3" flared port. These are the pre-made, cut to size "Precision" ports. These are of course adjustable in the middle section. My own experience finds people making their ports way larger in diameter than they need to be, which relates to longer ports."

Aren't the port diameters they are recommending too small, I mean 3" port for a 15" woofer of any decent xmax will cause port compression/chuffing? How do we take these recommendations? Are they saying that we are always conservatively estimating port dia and going for overkill?

Thanks and Regards,
WonderfulAudio

I searched the diyAudio site for any reference to the 1 inch screw on JBL PTB99HF-1 Waveguide. 6 inches square. 90 x 90 degrees.

I came up empty.

Anyone use it in a project. Listen to it or have anything to say.

I am thinking of possibly applying it as the top end in a bookshelf.

I have a pair plus a pair of JBL 2408H-2 compression drivers to test drive.

I will post some measurements if there is an interest.

Thanks DT

Hi,

I just bought two pieces of Aiyima 07 TPA3255 amplifiers and also bought 48V SMPS for them. But later learnt that the manufacturer advises not to use SMPS for it but use power adapter instead. Well, first of all, what's the difference between them, technically both are SMPS only?
Click this link for the actual listing

Thanks and Regards,
WonderfulAudio

I built an amplifier using several TDA7293 chips connected in parallel to make good use of my extra stock. The result honestly surprised even me!

I added a buffer stage at the input using opamps like the OPA1641, OPA1655, or OPA627, because I'm using an ALPS RK27 potentiometer for volume control directly at the output of a NOS DAC.

If you prefer, you can easily disable the buffer. Simply remove the opamp and short pins 2 and 3 of the socket.
In this case, R2 should be 47K, and you should remove both C23 and R1.
If you would like to keep an RC-filtered input instead, use R1 = 100Ω and C23 = 100pF.

Now, I’m excited to share some measurements with you!


EPIC W



1W Measurement (2x42VDC)



Output Noise (input shorted)



Schematic



Positive Regulator



Negative Regulator

Hello everyone. I'm looking for any suggestions or advice on getting sheet metal parts fabricated. Seems to me that a decent number of you all are building with custom sheet metal parts. I have no problem doing the CAD and generating STEP files, but I don't have the equipment to do the fabrication. I'm aware of a few options:
1. China, e.g., pcbway. I've used them before, but shipping and taxes are insane.
2. Online fabricators, e.g., Xometry, Protolabs. The quotes I'm seeing seem insanely high.
3. Local fabricators. There's plenty of them but don't know if they're set up to do one-offs. I plan to look into this.
4. Local makerspaces. There are a handful of them but don't know if they'd have the needed machines. I plan to look into this.
Any options I'm missing? Any suggestions? Any advice will be much appreciated.

Hello, All!
Just joined today as I found a very useful guide here on using Hypex Filter Design, thanks to DannerD3H.

I have always been a music and audio fan and find acoustics and speakers particularly fascinating. I always wanted to design and build my own speakers but never got to it, mainly due to lack of space to use for woodworking (I live in a small flat). But still decided to go for it. I will work around the difficulties somehow. If there is a will, there is a way.

I have reasonable understanding of audio, electronics and design process and ok to use my hands, but I have almost no experience, so face a steep learning curve.

First thing I did is buy the Loudspeaker Design Cookbook. Reading it now. Learning curve.

I have a pair of old slim floorstaders (description to follow) that I intend to convert to actives. This will help to initially avoid much woodwork, while still learning about drivers, crossovers and amps and box interaction. This will be done in two steps:

Step 1 - add Hypex Fusion amp and use existing drivers and enclosure as is

Step 2 - replace the drivers for better specced ones, modify the box

This will hopefully take me to a future point of fully building larger speakers and maybe a sub. One day.

So far I have bought a Dayton UMM6 mic, a Fosi V3 amp and just about managed a few measurements in REW of the speakers in passive form and of individual drivers. I managed to install on old version of HFD software on an old Win XP (!) laptop and hope to use that to program the FA253s when they arrive later this week.

I do stumble a lot and have lots of questions and definitely need some help. I will be asking here and would appreciate any help from the more experienced members.

I will make a post with the existing speaker details and maybe a few other things I am struggling with.

FWIW I do have some forum history on a couple of HiFi forums: Hifiwigwam and Audiosciencereview.

So, wish me luck.

ACA Clone Amp

This ACA clone design by JPS64 is only suited for a maximum 24V psu. The design of the amp board inhibits the Resistor mod that is prevalent in the Pass ACA pcb’s. I have implemented all the capacitor mod’s and whatever resistor mod’s I could according to member Tungsten Audio’s recommendations for the Premium build. I was planning a 24V smps for each amp board.

Included are a set of FQA70N10 MFets for Q1 and IRFP140N Mfets for Q2 for each board.

I also would like to include an H2V1 2019 preamp kit that I received from NP free of charge. This is the complete kit with the J112 fets.


I am asking $60 USD, plus shipping for the 2 ACA clone boards. H2V1 will be included.

Please see pic below,

Thanks,

Myles

Xmas amp-TDA7293 Chip Amp



I have a working dual mono Xmas amp that I have removed from a hack test chassis. This setup produced very nice audio through my test speakers.

What you will purchase is 1 x IEC/EMI power module, 2 x Antek 3225 toroidal transformers, 1 x SFP soft start module, 2 x All C’s psu modules (27.2K uf per psu), 2 x amp boards w/TDA7293 chips, 2 x RTR SSR speaker protection modules c/w, 2 x low cap psu modules (no charge for low cap psu since hand made).

All the wiring, the 2 inputs, speaker outputs, and all the wiring I disconnected to make a good pic will be included with tape tags to where they should be reconnected.

Asking $350 USD with the transformers, and $250 USD without the transformers, plus shipping. Please see pic below,

Thanks,

Myles

diyAudio Universal Power Supply Circuit Board v3 illustrated build guide. (October 2013)

(Any photo with a link directly below will go to full-size file of the photo)

This build guide will show a typical use of the diyAudio PSU v3 circuit board. This specific build will be suitable for any of the Pass/Firstwatt amps that use a +/-25V supply. If you need a higher voltage make sure you use capacitors of a suitable voltage rating for your project. You may always have a higher voltage rating, but do not use a cap with a lower voltage rating than your rails.

Useful Links

BOM - https://www.diyaudio.com/forums/images/diy/store/board-documentation/P-PSU-1V30/P-PSU-1V30-bom.xls
Schematic - https://www.diyaudio.com/forums/ima...mentation/P-PSU-1V30/P-PSU-1V30-schematic.pdf


PSU18 - My Photo Gallery


((Do not connect 2-leg TO-220 diodes as shown. See photos in 'heatsink' section.))
PSU36 - My Photo Gallery
Fully stuffed






PCB scale

Dimensions -


PCB dimensions





PSU14 - My Photo Gallery
The heatsinks are one inch post spacing. Look at the BOM for a specific part suggestion and find something similar that you can use. The sinks I used in this guide are of the same outer profile, so they fit the pads perfectly, but are quite a bit taller. A number of parts will be available that will work.


IMG_2134 - My Photo Gallery
This board can accept capacitors of up to 35mm diameter.



Equally important is the lead spacing - the caps should be 10mm 'snap in'. 10mm radial leads will work as well, but usually the bigger diameter caps have the 'snap in' leads.

For more information on dimensions of the specific parts, please consult the BOM for suggested parts, and cross-reference from that part's datasheet. http://www.diyaudio.com/forums/images/diy/store/board-documentation/P-PSU-1V30/P-PSU-1V30-bom.xls

Board features -


The bridge diode section of the board can utilize either TO-247/TO-3P (larger) package devices or TO-220 (smaller). If heat dissipation / heatsinking is not an issue, you could also use conventional axial-leaded diodes. (Not shown.)


IMG_2135 - My Photo Gallery
If you would like to use snubbers on the rectifier diodes you will find that there is room for them on the top of the PCB, and inside the heatsinks.


IMG_2141 - My Photo Gallery
If you don't find enough room there, or would like to try a different snubber layout, there is plenty of place to connect on the bottom of the PCB, as you will always have one of the d=sets of diode pads empty - you can only use one type of diode at a time, for example if you are using the TO-220, the TO-247 pads will be empty and you may make connections there.


IMG_2142 - My Photo Gallery
For designs that require one, there is also room for a snubber on the output. (Per rail)

Also worth noting, in this photo you can see the multiple solder pads for the output - the row towards the edge is for the euroblock connectors, and the inner row, with the larger pads, for wire. There is also a place for a blade terminal. (Near the board edge, on the outside. To be better illustrated in a later photo.)



Building / Stuffing



PSU41 - My Photo Gallery
This photo shows all the parts that will be used in this guide.
Starting at top and circling clockwise -
Capacitors and 'euroblock' connectors
(8) filter or 'pi' resistors
Diode heatsinks and diodes (TO-220 package shown)
(2) bleeder resistors
LED and LED resistors
AMP terminal blades

As this board has the scoring to let you separate it if you so choose, you need to notice that there is no connection from the diodes to the first capacitors nor across GND. These must be connected.

The PCB has no connection from diodes to capacitor.


The PCB also has no connection to make GND.

Since I am planning on keeping this PCB intact for the amp I am building, I need to make a connection form the diodes to the capacitor bank, and a connection to establish ground.


You can see all the links here (diode links not soldered in this photo)


GND links. The pads on most of this PCB are all through-plated and big enough to solder from the top if you choose.


PSU28 - My Photo Gallery
In general stuffing should be from the smaller devices to the bigger devices, so the resistors and such should be first. The filter resistors are on the outside, then the LED and LED resistors (the small brown one) and inboard are the bleeder resistors.
The silkscreen markings at the LED pads are slightly obscured, and the break in the circle, indicating where the flat of the LED should go (cathode, negative, short leg) is a little bit confusing. The legs of the LED go as shown. You can also see another link at the top of the PCB where I joined GND together.


The blades are actually taller than the euroblocks, so don't solder them first!



PSU27 - My Photo Gallery
The output edge shown with all the connectors in place

Capacitors -



As mentioned before, this PCB can accept caps with 10mm lead spacing and up to 35mm diameter. This photo shows 35mm caps next to 30mm. You will also commonly find some appropriate values in 25mm diameter.


PSU32 - My Photo Gallery
The addition of the large solder pads has obscured the markings on the PCB and the ' + ' mark is somewhat hard to make out. In each case the Positive side is marked with the open rectangle and the negative the white or filled-in rectangle. Remember that electrolytic capacitors are usually only marked on the Negative side.


PSU9 - My Photo Gallery
Note capacitor direction - you can see the negative markings on each capacitor.

Heatsinks -





The heatsinks used in this guide were chosen as they were of proper dimension to fit the PCB, and in-stock at the time I ordered them. They are a little tall, but as Nelson Pass says, there is no such thing as too much heatsink… I do suggest you try to get something that will fit a TO-247/TO-3P package as it will also mount the TO-220, whereas the slightly narrower inner profile of this heatsink will only mount the smaller diode. Regardless, it's quite easy to get really nice, suitable diodes in whichever package - you want 20A, 200V minimum diodes.


A little grease is helpful on the full-pack devices. Secure to the heatsink with a nut and screw. This is a 4-40 screw, about the same size as M3.

Please Read - If you use a conventional TO-220 diode or TO-247/TO-3P it's a very good idea to use an insulator between the device and the heatsink. But it's not necessary - although if you choose not to the heatsinks will probably be live. The heatsinks themselves solder to the PCB and are in holes that have no electrical connection, and aluminum anodize is actually not very conductive, but I would still suggest using an insulator. (Or a full-pack TO-220)



Feel free to snap off the diode section and use bridges. They work and sound great!

NOTE - I strongly suggest not separating the capacitor board if at all possible. With it intact, you can run multiple jumpers (as shown) to tie GND together and have a low-impedance, and therefore quiet GND. Splitting it will complicate making a quiet circuit. FYI.


Example wiring.

Hi

I built the RCA 12AU7 cathode follower preamp, and I’m finding it to be a bit bright/Sibilant sounding. It sounds bright with both Mullard, PSvane and Electroharmonics tubes in it. And it’s bright with every amp I put it in front of (DIY store Sony VFet, Hiraga Super 30, Type 45 and a couple of others…)

Been reading about subbing a 12BH7 for the 12AU7’s, and from what I’ve been reading, they could help with the top end.

I’m using a Hammond 369JX transformer and an EZ81 rectifier for the power supply. The transformer has 2.5A available for the heaters, which I believe is enough for the 12BH7s and EZ81 (which add up to 2.2A)

Any thoughts on this swap, and if it will help with the bright top end would be greatly appreciated.

Tyanks

P

It's a bit of a long story - you can read the whole thing on my website at http://www.pmillett.com/meamp2.html.

I designed an EL84 push-pull amp. It evolved from ETF.24, where a team including myself, John Bollinger, and (remotely) Douglas Piccard, and Jeremy Epstein designed and built an amp for a shootout at.

The basic circuit came from Douglas, using an ECC88 in cascode with N-channel MPSFETs as the front end. He and I had both done some designs using feedback from an ultralinear tap to the driver many years ago, and that was a starting point.

Here's the schematic, or download the whole thing as a PDF file: http://www.pmillett.com/file_downloads/meamp2_sch.pdf



The amp measures very well, around 0.02-0.03% distortion at 1W. The web page has full measurements.

I have to say that the ECC88 / MOSFET cascode diff amp is a simple but excellent front end for a push-pull amp.

I asked AI. If there's something better please comment below. TIA

Question: Can you recommend good quality brands of wood polish mentioned in the list below for vintage KEF speakers from 1974?
(I live in Portugal, so please only European products)
• 1st. Furniture polish
• 2nd. Scratch remover
• 3rd. Wax stick
• 4th. Wood stain or varnish (for exposed wood)
Important considerations:
• Do not use polishes that contain silicone or excessive oil.
• Although it is most likely a varnish, try to confirm the original finish if possible. This will help you choose the right restoration products.

Answer: Absolutely! Finding quality products in Europe for the restoration of your vintage KEF speakers is perfectly possible. Since you live in Portugal, I will recommend some European brands that generally give good results for the types of products you are looking for.

It is important to note that the availability of specific brands and products may vary by store and region in Portugal. I recommend checking out DIY stores, furniture restoration stores, and some larger drug stores.
Here are some suggestions for European brands in each category:

1. Furniture Polish:

• Borma Wachs (Italy): This Italian brand is well-known for high-quality wood treatment and finishing products. They offer a wide range of polishes for varnished furniture that are silicone-free. Look for products like “Borma Wachs Polish” or liquid waxes specifically for varnishes.
• Liberon (UK/France): Although this brand originated in the UK, its products are widely distributed in Europe. Liberon offers excellent wood polishes, including silicone-free options like “Liberon Beeswax Polish” (pure beeswax, which can give a soft shine to varnishes, but test first) or varnish-specific polishes (“Liberon Furniture Polish”).
• Blanchon (France): Specializing in products for wooden floors and furniture, Blanchon offers good quality polishes to maintain and enhance the shine of varnished surfaces. Check out their range of "Huiles d'entretien" (maintenance oils) or liquid waxes.

2. Scratch Removal Product:

• Borma Wachs (Italy): Again, Borma Wachs offers products specifically for repairing scratches on varnished wood, such as touch-up crayons ("Retouch Crayons") or fine polishing compounds ("Abrasive Paste for Wood").
• Liberon (UK/France): Liberon has products such as "Liberon Scratch Remover" which is formulated to disguise superficial scratches on wood finishes, including varnish. * Möbel-Reparatur-Set by Akemi (Germany): Although best known for stone products, Akemi also offers furniture repair kits that include materials for removing scratches from wood and varnish.

3. Wax Filler Sticks:

• Borma Wachs (Italy): Borma Wachs has a wide selection of “Wax Fillers” in various colors to repair deeper damage and scratches in wood and varnish.
• Liberon (UK/France): Liberon also offers “Wax Repair Sticks” in various shades to fill chips and scratches in wood furniture.
• Picard (Germany): Picard is a German brand known for tools and materials for craftsmen, and they offer wood repair wax sticks in various colors.

4. Wood Stain or Dye (for exposed wood):

• Borma Wachs (Italy): Borma Wachs offers a wide range of wood stains and wood dyes in a variety of colors and shades, ideal for touching up areas where the varnish has been damaged and the wood is exposed.
• Clou (Germany): Clou is a German brand specializing in varnishes, paints and wood care products, with a good selection of wood stains and paints.
• Sayerlack (Italy): Although more focused on industrial finishes, Sayerlack also offers high-quality wood stains and paints that can be found in specialty stores.

Important Considerations (to Remember):

• Confirm the Finish: If possible, try to confirm that the original finish is indeed varnish (which is highly likely for these loudspeakers). You can do this by checking whether the surface is hard, smooth and water-resistant. Varnish usually forms a thicker, shinier layer than wax.
• Avoid Silicones and Excessive Oils: The brands mentioned above usually offer silicone-free options. When choosing a product, read the description and ingredients carefully to ensure that it does not contain silicone or excessive amounts of oil, as these can interfere with future finishes or attract dust.

For Sale:

Discrete R-2R DAC Hat for Raspberry Pi ( Version V2.42 )

Up to 24bit 384K, non over sampling .
Support Pi 2,3,4, and 5
Distortion 0.004% ~0.005%
Price: USD196.00

The difference between this V2.42 ad older V2.4 :
V2.42 using larger FPGA and most of the job has been done in the FPGA.
No MSB adjustment preset required.
The PCB size is the same as Raspberry Pi, so that I can install \ modified a raspberry pi tower case
Support Pi 5


Shipping via FedEx Priority International, to USA = USD34.00 , Canada = USD32, Most of Europe countries = USD35.00

Please PM if you are interested, Thank you.

** Edit 2 August: Just finished assembling another 5 pcs and available for purchase **

Looking for one pair of Scanspeak Revelator 7" 18W/4531G 4 ohm drivers.

I have a US address in Port Huron Mich 48060.

I will pay via Paypal as well...

Let me know what you have.....

At long last, I present the DIY Biamp 6-24 Crossover.

Attached is the "owners manual" which contains everything I have to say.

Basically it is a complete stereo biamp crossover which has 6, 12, 18 and
24 dB/octave slopes and filter poles independently adjustable over a
6:1 frequency range.

Quantities of the "Essentials Kit" are ready to ship to the store, and
should be available shortly. It includes the pc board and the selected
Jfets + bias resistors. The part list is complete and everything can be
obtained from Digikey and Mouser. I expect a "completion" kit to also
be offered.

6L6 has been provided with an advance copy to enable one of his
popular build guides, and Mike Rothacher has put together a simulator
for customization.



-

Hello everyone very exited to be a member of this forum

Few years ago, we had enormous fun in funny named thread : F4 Beast Builders

Well, you can call it Group of Hysteric Housewives Brainstorming 😛

Result of that was that I had myriad of back of napkin sketches, and after these I started simulating ...... and simulating ... and simulating

After myriad of sims ( out of sheer enthusiasm I even made pcb files for some of iterations), I finally had made nice smallish channel pcbs, containing OS having different-ish approach to biasing than Papa's original XA25, while FE was in principle same as Papa's, but with few beautiful quirks, of which I was damn proud (yup, Mighty ZM reinventing Da Wheel, time and time again)

And they were sitting, populated, on my shelf ........ always being pushed to bottom of list; I knew they would work, but somehow I wasn't content with overall picture

Now, recently - besides revising biasing mechanismus for SissySIT ( resulting in R.3) and few other amps, I also made FE called Plethora of Pinjatas ( or just Plethora, short) and found interesting to combine it in sitting Babelfish XA25 project

Plethora Fe having both SE and Bal inputs as matter of choice, called to adding another "2" in name , so result is Babelfish XA252

Plan is also to have iteration of DEF OS ( real SIT, no emulation in form of Schaded Mosfet), thus addition of "SIT" in name, so Babelfish XA252 / SIT

Find enclosed cumulative schematic, and will do edits of this post, if and when needed

OK1-OK2-TH1 .......... 10A limiting circuit, Savior of Our Souls, blatantly stolen from Pa 😛


amp is phase correct , Papa's fave gigglywiggly graphs sez that 2nd is negative phase

all measurements made with SE input, neg leg input grounded


edit on 18.07.2021.

Babelfish XA252 SIT - post #64 Babelfish XA252 / Babelfish XA252 SIT / Babelfish XA252 SET

Babelfish XA252 SET - post #119 Babelfish XA252 / Babelfish XA252 SIT / Babelfish XA252 SET


edit on 18.12.2022.

separate schmtc for Full Mos, SET, SIT iterations, post #624

ignore notes on schematics about "do not mount" - just follow schematics

read all down for separate schmtcs, Extra-carefully made set of files, for each of 3 amp iterations

short setting procedure:
*********************
P1 is for DC Offset, P2 is for Iq


do not forget to have grounded neg input , presuming you're using it SE input, but also ground positive input, temporary

no load at output

P1 irrelevant for start how it's set

P2 set to max value - check with probes across unpopulated Rt, that one being in parallel with P2; that way pre-set is min Iq

I don't care for left-right orientation of trimpots - never taking care about that when making pcbs - too much times in my service work I

expected some logic with trimpots orientation, just to be confused and from then on, I'm just using DMM as guide

leave JP1 open for start

advisable to put temporary fuses in rails - say 2A

if you have variac, use it

of course, regular praxis - one DVM across rail sense resistor group ( + or -, irrelevant) - Iq observer

second DVM at output, offset observer

power up, have an eye on Iq observer;

DC offset for start - good even if few volts, but normal to expect few dozen of mV

now, fiddle with P2, slowly, to get half of intended Iq

observe DC offset is it still OK


give it time to develop some heat in heatsinks, then increase Iq to 75%


if everything is stable, close JP1 ( alive, no need to power off for that), try to minimize DC offset as much you can

if that is done, open JP1 ( alive, no need to power off for that), wait for some time to get closer to temp equilibrium, increase Iq to

final desired value


that's it

try few lazy powering off - powering On sequences, observe behaviour

if everything is OK, power off, remove temporary fuses, wire rails properly

proceed/repeat procedure with second channel
*******************

edit on 22.12.2023.

set of files for last iteration, Post #1386 - consider it as hair-splitting changes, gilding da lilly, whatever; ZM playing in Sandbox...

read down.....

Edit on 07. Jan. 2024.

Extra-carefully made set of files, for each of 3 amp iterations, post #1462 https://www.diyaudio.com/community/...2-sit-babelfish-xa252-set.373443/post-7560120

Edit on 03.02.2025.
Important revision of protection circuit: read post #2573, https://www.diyaudio.com/community/...2-sit-babelfish-xa252-set.373443/post-7919078

Hey all,

I've started going down the DIY rabbit hole a little deeper and find myself in the need of additional testing equipment than I've been using for tube builds. Currently in my toolbox are a few cheap-o DMM's, a Fluke 117, Peak LCR45 and a Velleman DCA55 Semiconductor Analyzer. Last summer I saw an old Conar 255 oscilloscope for $20 at a garage sale but now I'm convinced I should just get something modern instead of doing a restoration and questioning everything it spits out. Maybe a fun future project but for now I'd just like to get up and going. Something modern-ish but am Ok with used if its a good bit of kit.

What do you guys recommend for a good testing / electronical / audio bench testing rig? I don't need to spend 10k but would like to start putting together a decent set up that will go for the long haul. Appreciate any recommendations!

So, I really hope someone with the knowledge and a generous heart can help me.

So, I have a HK990 amp and was doing the bias adjustment as my right channel was running hotter than the left. Looking at the manual, it says this:

AMP Adjustment Iding Adjustment
Precaution for handling measuring instrument.
The ground side of the measuring instrument to be connected to the speaker terminal of this unit must be kept in floating condition because this unit is equiped with the floating balanced power amplifier.

So what's the problem, you ask? Yep, I shorted the probe between the pad and something else, maybe normal ground.

The slow blow fuse blew, needless to say, as does the replacement fuse.

Steps taken so far:
1. Disconnect the transformer for the right amp and power up. No problem, everything works as usual with the system and the left amp.
2. Examine fuse board - nothing burned or odd found.
3. Removed and examined RHS amp. Visually, I found nothing. No burn marks. I tested, in circuit, the output transistors and they all behaved the same. I didn't fully disassemble the heatsink so the diodes mentioned in the schematic might not be visible.

So, needless to say, I need help. I've rebuilt numerous amps without doing something so stupid before, so I feel confident in replacing components to fix this, I just need guidance.

Attached are the schematics and parts list.

Please help with any suggestions on where to start. I'm actually out of town but willing to add components to an existing order on the chance that it's the problem.

What do you guys think?

Thanks for your time and take care,
Peter

Hello,

I got an Akai AM2450. I am trying to understand a bit of the schematics. (here joined)

Here the input of the amplifier stage. The differential pair takes its input from the pre-amp.

At the output of the differential pair, V+ is connected to the base of a PNP, and V- to the base of the NPN.

I am wondering what is this schematics doing ? In particular, they give voltage when no inputs, and I see 2.3V between the NPN base and emitter, which surprises me (0.7V would no be a maximum before failure ?)

Thanks !

Hi all.
I hope this finds everyone well and able to help a desperate non-techie. I've had my Yamaha Stagepas 600bt for 4 years. I'm a solo singer who downloads backing tracks and uses his Samsung phone to play them via a USB C to 2RCA that goes straight to the mixer.
During the last 3 gigs in different venues, the sound (backing music only) has been cutting out. No pops or cracks, just stops playing sound through the speakers.
The mixer limiter (and master volume) is nowhere near max, the mixer itself or power doesn't switch off, the phone doesn't switch off or go to sleep (and the playlist display shows the track as still playing!) The mic is still active too but no sound from the phone coming out of the speakers? Had the same phone/set up for a while and never had the problem before.
The attempt sticking plaster was to turn it off, unplug, replace and go again. It then worked but happened again after about 45 mins. I then wondered if it was overheating so I took it from it's casing in the back of the speaker before the gig, but after 20 minutes, it did it again.

The challenge is that it's happening completely arbitrarily. Sometimes on the very first track, then it might be ok for 30 minutes then cut out in the middle of another track. Last night I played a whole 90 min set without issue and it stopped 30 seconds into my very last song. Because it's so randown, it makes it hard to pinpoint a simple issue. I've set up at home and wiggled and checked cables in the hope i can 'trip' the issue and eliminate a dodgy cable, maybe, but after 2 hrs, still no issue!
I checked the points for dirt or fluff, ordered a new USBC to 2RCA last week in case it was this, (just deducing that the issue looked like it was from the phone to the mixer) but last night the issue came back (with a vengeance). At the start, midway through and right at the end.
As well as being annoying, it's sooo embarrassing. Can anyone help with what might be causing this and how I might be able to fix/prevent without 'contacting Yamaha' or buying new kit? Both of which is could do without.
If you could, I'd be forever indebted.
Many thanks,
Salty.

Neighbor downhill from myself and I are working on an idea for Halloween, want to build an extremely narrow speaker.

Want to project sound to the intersection 450 feet away at whisper to conversation levels, roughly 40-70 dB so modest goals there. I calculate this to be about 110 dB at source, which seems perfectly achievable

Would like to have very narrow dispersion to keep sound inside the intersection that is 50 feet wide, and to normal height of people, really looking at a design goal of 0.5 degree by 6 degree dispersion. This is so far outside what I have ever seen I don't even know if that is possible.

I see commercial waveguides for line arrays for narrow vertical dispersion of around 15 degrees, but have wide horizontal dispersion.

Do not want to blast people on the sidewalk directly in front of our houses, and will place speaker on my roof which would elevate it about 20 feet higher than sidewalk and street,

Mostly wanting to achieve speech frequency ranges so maybe 300 z to 2k Hz, but wider range would be better. Care about intelligibility but this is not a hifi setup by any means.

I have built tapped horns before, and have understanding of line arrays, but have only designed subwoofer horns before.

Not even sure a horn is the best way to go about this, open to options.

So what is a likely way to achieve these rather odd goals? Or better question, is the angle requirements and intelligibility achievable, and if so how?

Paraline, unity horn, array?

I have multiple amplifier choices and DSP to work with as well.

I assembled a zhiliaudio ear 834. Poked around with infra red temp gun, everything seems good except the zener ladder is 180F. Seems to me that's higher than expected. I installed (4) 1n5373, voltage measures 285 DC. Input 300 VAC. Currently have choke in place of the 1k 3watt resistor. Verified all power supply resistors in correct position and value.
Thoughts on the temperature?

Hi, I'm a budget PA engineer from Japan.
I use a lot of used equipment, so there are a lot of problems.
I sometimes fix things myself, so I'd be happy to share information with you guys about that.

Who can remember listening with friends to Mortal combat song, and the unintelligible words:

Test your might, Mortal combat, sounded like : whowwoodtlungtodwwoooo (mortal combat) tksssssss yuourrrrr migshhhhht (test your might).

"Hello to all fellow DIY audio enthusiasts!

I'm reaching out from Lake Mary, Florida, hoping to find someone with talent and experience in CAD design who might be able to lend a hand with a very exciting project for me.

I'm in the process of redesigning a somewhat older passive line array model to give it a new lease on life as an active system. My idea is to use high-quality amplification modules like the Hypex FA 123 or FA 503 to power it. Additionally, I'm optimizing its component configuration, replacing one of the 8-inch drivers with a 6.5-inch one, and modifying the angle of the rear of the enclosure to achieve more precise and modern vertical dispersion.

Although I have a clear vision of the result I want to achieve and have managed to generate the new measurements for the enclosure with the help of AI tools (ChatGPT, Copilot, and Gemini), I've hit a significant roadblock: I have absolutely no idea how to use CAD software to create the technical drawings necessary for construction. I've tried learning on my own several times, but the learning curve has been too steep, and I feel frustrated by not being able to translate my ideas into a format useful for a carpenter.

Fortunately, I have the original plans for the passive model in various digital formats, and I have clearly defined all the new measurements that I've calculated for the redesigned enclosure. The only thing missing is the magic touch of someone with CAD skills to integrate this information and create the drawings or 3D models that will allow the carpenter to do their work accurately.

If anyone in this amazing community has the knowledge and the goodwill to offer their help, I will be immensely grateful. Your contribution would be fundamental in making this project that I'm so enthusiastic about a reality. Any help, no matter how small it may seem, will be greatly appreciated!

Thanks in advance for any light you can shed on this and for the generosity of your time and expertise. I eagerly await your comments and potential collaborations!"

Hello,
I am Nikola from Bulgaria. I like building stuff and audio is my hobby.
Now I am building HifiSonix kx2 and clone of Accuphase E350.

Regards,
Nikola

V-FET lottery amp #038 P-channel from first lottery
Original, unmodified, perfect condition
In addition: 2 Bulwark FE and 1 Tuba filter
Asking price: 700CHF + Paypal Fees and Shipping

I got two Carver TX-11 tuners and I got them both to work, but power supplies seem to run hotter than a solid state tuner ought to. I recapped one of them, replaced the 22 ohm 2W power resistor with a new 3W wirewound Vishay PAC series. Still, that resistor heats up to 200-210 deg F (93-100 deg C) in normal use.

The 2SD330 power transistor runs about 140 deg F at the heatsink. All other PS components run at near room temperature.

If anyone out there still owns a Carver TX-11, I would like to know how hot it's supposed to get in normal operation, just so I don't go chasing a fault that does not exist.

Schematics attached, PS is at bottom right, R701 is the hot resistor. Unfortunately I am not skilled enough to calculate the as-designed resistor's power dissipation from looking at the schematics.

All feedback is welcome. Thank you in advance!

The Iron Pre is now listed in the diyAudio store for anyone to purchase.

Until the 'Build Guide / Build Thread' is created, this post will contain all current schematics and notes for the Iron Pre sold through the diyAudio store. Check back frequently to ensure you have the latest files.

Sep 14 2023 - Below is what you're waiting for! See some awesome information and help from 6L6 on the SE build. A new thread and the guide using the web interface will be posted ... soon. Post #2291

Background

Hello Happy DIYers / Greedy Boyz!

I am thrilled to announce that Zen Mod's Iron Pre essentials kits will be offered in the DIYAudio store. This is not a group buy. You can learn more about the project in the thread linked below.

https://www.diyaudio.com/community/threads/whats-wrong-with-the-kiss-boy.293169/

Highlights include matched Toshiba JFETs from Nelson Pass and high-nickel CineMag transformers. 6L6 has volunteered to post one of his incredible build guides also.

If you're a Smiths fan, you may ask, How Soon Is Now? They should be available for order before the end of the year. At this time, we have enough parts sourced for 100 SE and 50 balanced kits.

The next obvious question is, how much? Costing is not final yet, but the goal is $100 for the SE kits and $125 for the balanced kits; a tremendous bargain. We have contingencies for all the parts, and we hope that this will be a permanent addition to the store. However, for now, we can only promise what we've got. Get 'em while you can.

Click the link below to see what will be included in the kit, answer a few questions about what you might like to see in the future, and get on the list.

Note - The n-channel JFETs will be 2SK370.

Quick and Dirty Startup Process

This happens after: the boards are stuffed, the AC supply is verified and connected properly, and I/O has been connected. Nothing needs to be shorted. Note the additional step for the V4 SMD version.

1. Set V+ and V-
   
   Adjust P1 and P2 for each board until V+ is +15V0 and V- is -15V0
   
   GND, V+ and V- pads are clearly marked on PCBs.
   Do not move forward if you cannot adjust the voltages to within 0V1 or if the voltage seems unstable.
   
   
2. For V4 SMD Only- Set current through JFETs
   • Set DMM to DCmV.
   • Place probes across R34 and R37 for SE or R40 and 41 for Balanced. You can also use square pads / test points near resistors.
   • Turn P4 and P6 respectively until DMM reads 14mV +- 0.05mV - See schematic.
3. Null DC offset
   • SE
     • No jumper caps in place for JP1 or JP2
     • Measure at center pin of JP1 and JP2 NOT between those two pins*
     • Turn P3 / P4 (V3 and earlier) or P3 / P5 (V4 SMD) respectively until voltage shows 0V +- 5mV
     • Cap the jumpers for your choice of gain.
   • Balanced
     • No jumper caps on JP+ or JP-
     • Measure at pin 1 of JP+ and JP- NOT between those two pins*
     • Turn P3 / P4 (V3 and earlier) or P3 / P5 (V4 SMD) respectively until voltage shows 0V +- 5mV
     • Cap the jumpers.​

Updates

4-May 2023

Edited 7-Aug 2023. All in-line photos have been removed. Please see attached files for all documentation.

5-May 2023

Updated Single-Ended BoM to correct 330R part notations in the gain stage to R28 and R29.

Attached are the Bill of Materials / Parts Lists - Note File Names for Balanced and SE

26 - May 2023

Updated SE and Balanced Bill of Materials to indicate that snubber components should not be installed.

Balanced BoM Filename - BOM_Store_Iron_Pre_Balanced_Dist_v5.pdf
SE BoM Filename - BOM_Store_Iron_Pre_SE_Dist_v5.pdf

27 - May 2023

Updated SE and Balanced Bill of Materials to correct and clearly note which diodes should be installed for input switching.

Balanced BoM Filename - BOM_Store_Iron_Pre_Balanced_Dist_v6.pdf
SE BoM Filename - BOM_Store_Iron_Pre_SE_Dist_v6.pdf

1 - June 2023

Note - No changes required. However, the packing lists some of you will receive may note LM336-5.0. That was a typo; apologies. The correct parts (as supplied and noted in the BoM) are LM336-2.5.

Removed the link to sign up indicating interest in kits. Those currently on the list will get first priority for the next round of kits. After that, they will be sold through the normal process through the store.

6 - June 2023

There are two gorgeous prototype chassis available; one designed specifically for SE, and one for Balanced. You can find some details in post #431. The depth for both chassis is 280mm. There is additional information sprinkled throughout the thread re: acceptable sizes and some potential part numbers for IECs, input / outputs etc. along with pictures of some examples. Please search first before asking chassis questions, and I'd recommend using the latest posts' information. Again, they are prototype chassis, and anything could change at any time until the design is finalized. The best source of information re: the chassis is directly from Modushop until they are sold in the diyAudio store. Timing TBD.

8 - June 2023

Added parts placement and pcb layouts for those interested.

30 - June 2023

V7 - Minor Updates to BoMs. QTY added. Ensure to check quantity per board against the quantity you need for your project. Added links to a popular online website to show examples of parts that will work for the connection between the main boards and the twister boards for input selection / LED power etc. Added generic descriptions for those that would prefer to select their own parts.

1 - July 2023

V8 - Minor Updates to BoMs. Added heatsinks for M3 if 12V relays are used.

7 - Aug 2023

I'm excited to say that more kits will be available very soon for 'round 2'. Continue checking this post (as always) and the thread overall for up to the minute updates.

In his graciousness, ZM has made some minor running changes. Changes are:

• Updated transformer snubber circuit.
• Easier positioning / mounting of the CineMag transformers in some situations.
• Changes to allow easier use of some logic circuits for input switching.

Boards that include the changes will note "2023" vs. "2021" on the silkscreen. The Twister board accompanying the 2023 boards notes V.3. Both 2021 and 2023 boards are included with 'round 2'. You cannot choose which you will receive, and you will not know which you will receive until they arrive. Do not fret if you get a kit with 2021 boards. If you need to use a particular type logic solution, there is a very easy modification previously noted in the thread, and the snubber is not necessary. The changes made were a kindness from ZM, but all 2021 boards can be made to function just like 2023 boards with a few user-tweaks described in the thread.

Note - The attachments have been packaged and note which files to choose for the respective boards. Previous attachments and in-line thumbnails / photos have been removed for clarity. The BoMs have been updated slightly for clarity.

9 - Aug 2023

There is a minor error on the silkscreen for the boards marked Iron Pre SE Zen Mod Labs 2023. The polarity notation for C11 visible when the cap is installed is incorrect. Ignore it.



13 - Aug 2023

His Mightiness created two graphics for how to wire standard pots for both SE and Balanced. Attached.

29 - Aug 2023

Minor updates to balanced BoMs. Removed reference to D15.

31 - Aug 2023

Added wiring diagram for AVC for SE. See post #2113 for context.

21 - June 2024

All testing for the Super Mega Deluxe version is complete. Kits will be back in the store 'soon'.

25 - September 2024

"Soon" is relative. 🙂. SMD kits are on sale. The schematics and files for the Super Mega Deluxe (SMD) have been attached in their appropriately named .zip files. Enjoy your builds.

26 - September 2024

A few people purchased the "completion" kits for the V3 and earlier boards and were wondering if they could be used for the V4 SMD kits. A lot of the parts are identical, but below is what you'll need in addition and to swap a few parts.

For balanced you will need:
4x additional 825R or 820R resistors - I like these Vishay BC 825R
8x 58R or 62R resistors - I like these Vishay BC 62R
4x 1R resistors - I like these Vishay BC 1R
8x 100R trimmers - I like these Bourns 3296 Series 100R Trimmers
4x 1uF film caps with 5mm or 15mm lead spacing - I like these TDK 1.0uF with 15mm Lead Spacing

For SE you will need:
2x additional 825R or 820R resistors - I like these Vishay BC 825R
4x 58R or 62R resistors - I like these Vishay BC 62R
2x 1R resistors - I like these Vishay BC 1R
4x 100R trimmers - I like these Bourns 3296 Series 100R Trimmers
2x 1uF film caps with 5mm or 15mm lead spacing - I like these TDK 1.0uF with 15mm Lead Spacing

27 - September 2024

Some potentially helpful additional parts in post #3784. If people have more helpful suggestions, I can add them.

3 - February 2025

Added diagrams for setting buffer current in V4 builds.

Dear DIYers,

I decided to throw myself on a DIY Lehmann BCL clone. I am a beginner and you should treat me as a fresh one.

I know my soldering and how to work clean and I'm a perfectionist but next to that I have barely the proper knowledge to make right decisions on circuitry.

Lately I have been reading a lot on this forum and other forums to gather more knowledge about different parts and what they are supposed to do. Got me a little wiser but not anything near my goal. That's why I want to share my project here. I hope to get some good tips here about my next few steps.

Since I am currently located in China, I can get my hands on a lot of parts easily and cheap and I ordered a clone PCB and a package of parts that was supposed to be almost identical to the latest version of the original BCL. The components are genuine from RS-components. The tranformer used was a german made BLOCK 40VA instead of the original custom made 30VA.







After I put it all together and put it up for the smoke test all worked fine and I was amazed what this machine was capable of even with stock components.



I decided to upgrade:

• Replaced transformer. Original 40VA BLOCK to 60VA BLOCK (just fits. Maximum size without any concessions or modifications to case) Also braided the cables for less interference like the original Lehmanns.
• Replaced input capacitors EPCOS MKP 654 1.5uf 250V with Mundorf MCap MKP 2.2uf 250V (Like Lehmann BCL SE version).
• Replaced all Wima FKP2 22nf 63V caps for ERO MKP 1830 22nf 63V caps.
• Replaced 2 Wima FKP2 100pf 100v 630V caps with LCR 100pf 150V .polystyrene caps. (als have some ERO MKP 1830 for these to try).
• Replaced 4 Nippon LZX 470uf 25V caps for Panasonic FR 470uf 35V caps.
• Replaced 2 other (opamp) Nippon LZX 470uf 25V caps with Panasonic Pureism 470uf 25V caps.
• Replaced cabling with Mogami Neglex 2549 cables. Soldered to the PCB.
• Replaced opamp with dual discrete opamp OPA111VM with class A mod with 2 x 2.7K resistors. (Still working on a better adapter with less components and soldered.)

A shielded Schurter powerswitch with fuse is on the way to light this baby up again.

Now I am looking to upgrade a few last things.

When looking at the original Lehmann BCL SE I see that the 22nf WIMA bypass caps are removed.



I replaced these with ERO's but I have learned that mostly the best cap is no cap. Capacitors are a necessary to block noise and stuff. My question would be: what can I do with these? Can I just remove them and check if that improves the sound while not creating noise or a big DC offset. I read some people bypassed these with copper wire? I am not sure why. I posted a PCB overview above.

Can someone with a bit of technical knowledge help me out on how and why the caps are there and what to do with them?

I am also doubting if I should upgrade the Vishay BC's for the SE's Mlytics. The Mlytics will cost me about $50 for a pair. Will this investment be returned in significantly better soundquality? I upgraded the transformer to 60VA will this have any influence on my choice for capacitor capacity? Also for the 470uf caps?

And maybe any other weaknesses visible in the circuit and component choice I could look into?

I hope I can get some guidance here. I am open to learning and your advice on these matters

Hello,

For sale is IanCanada's Audiophile master mode digi re-clock streamer using TransportPi Digi II and IsolatorPi III

https://iancanada.ca/products/20b-transportpi-digi-audiophile-grade-master-mode-digi-transport-95-00

I bought TransportPi Digi II and Isolator Pi III couple weeks back but had to change plans (can provide dated receipt for proof of purchase).

Items for sale: $190 + Shipping
1. TransportPi Digi II
2. IsolatorPi III

Please send me a message if you are interested.

Regards,
Subbu

Good morning everybody,
I have read with much interest the paper by Jan Didden on a diy direct drive amplifier for QUAD ESL 63 in: https://audioxpress.com/article/you-can-diy-edd-a-direct-drive-amplifier-for-electrostatic-speakers.
I am and have been a lover of QUAD electrostatic speakers for the last 40years and think that the ESL 63 (properly maintained), are the best of them all ,including their successors , but the building of a direct drive amplifier is beyond my limited abilities . However, the search for the best amplifier for QUAD electrostatics still remains (imho)
In particular I would appreciate your opinion and direct experience on driving them with high power class D amplifiers such as Purifi or Hypex n-core cx.
Many thanks
Bruno
PS: I have both the 63s and 2905s and, at present, drive them with both tubes (Quicksiver V4_) and ss amplifiers (Spectral studio 160) .In my opinion tubes are a little ...better ,but only a very little...

Folding a new bass horn design or adjusting the dimensions of an existing design to meet a specific requirement can be somewhat of a challenge and prone to error. To make the process easier and to avoid errors as much as possible, I've created a number of different Excel workbooks that can assist with the folding process. All of them should be considered as "works in progress" as I'm continually adding new features and of course fixing the odd bugs that I come across, so always make sure to check here for the latest version before using any of these workbooks. Some of them I've actually used to design and build my own subwoofers (the best way to confirm that the workbook in question works), and in those cases I've included a link to the project sin question. If you have any questions about the spreadsheets, please post them to this thread, thanks!

The latest versions of the workbooks are available at this location:

The Subwoofer DIY Page

Hello, today I built my first DIY amp with an LJM L15 and when I switched it on it exploded, this came as a surprise as I had made sure that the output voltage from my power supply was ±55 V I had also triple-checked my wiring to make sure that I wasn't plugging the VCC and VEE in wrong. I am planning to buy a new pair of L15s to retry this build, but I want to know what went wrong. I've attached a coupling schematic and pictures of which transistor blew on one channel and where the PCB burned out on the other.