I’m about to embark on building the Lampucera DAC, as described by Serbian YouTube star iiWi, You can see the video here:
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He claims this is the best DAC he has ever had in his listening room.

The DAC is a precursor to the Lampizator line developed by Lucasz Fikus. Details, documentation, from iiWi here:
https://drive.google.com/drive/folders/1MvSMdEsZ8DPtGMXrzUgQ7ceyAVS86uxO?usp=sharing

Ebay starting kit from HKaudio1 (Lawrence, who has been very responsive):
https://www.ebay.com/itm/1863217614...zPANM_6Rl2&var=&widget_ver=artemis&media=COPY

I’m probably not going to use Lawrence’s included tube output stage, instead following iiWi’s version with the 6N6P [but maybe experiment with the eBay one first].

My first two question areas, for which I am seeking advice:

1. What do you recommend as a source for metal chassis that is easy to mod, and large enough for transformers and giant capacitors as iiWi had?
2. If you look at the schematic, it is based on 220V transformer on input. I have US 120V input. What transformer changes are needed?

• A. Best to stick with toroidal transformers? Seems like a lot of audio guys prefer laminated. Can you recommend any source that is up to the standard here?
• B. I assume it’s easy to find a 120V to 6.3V transformer for tube heater. Any suggestions?
• C. It looks like the anode supplies start with 120V. Does that mean I don’t need any transformers for them?

If anybody has done this, and/or has advice to offer, I’d be most appreciative.

First of all, big thanks to Hephaïstos (ascended Master), to Peufeu, to Douglas Self, to uncle Charlie, DestroyerX, and to all those that investigate on thermal memory distortion and finally to everyone who is willing to help me here.

This is not a thread about THD. It is a thread about experimenting with putative Low Thermal Memory Distortion or LTMD circuits.

Edit: just at the Lions Gate of 2022 I found the best output configuration. Check out post #806 (I attached the diagram down here) for the latest official Bootstrapped Darlington output configuration.

Edit: it also runs very well with VFETs as bootstrap element for the outputs.



I am proposed to implement the mods that Peufeu studied for diminishing putative thermal memory distortion effects on solid state amplifiers, but adding my own experiments on the output section, which Peufeu did not (unless I am not aware of that) address. In fact, I began my research modifying the outputs (Cascode all thy outputs), that is why Peufeu's articles were so interesting to me. I took the liberty to re-post the proposed amp from Peufeu. (it may have a minor error on the cascoded CFP like my experiment proved)

I have no electronic background; only the experience and scarce knowledge I obtained here, so be patient.

The blameless amp is the prototype to modify and since I have a Blame ST from Destroyer X, the idea is modify it section by section as Peufeu proposed and evaluate if there is any improvement in sound to be achieved.

I already swapped differential amplifier BJTs (Q1 and Q2) for cascoded CFP (J103 P channel JFET cascodying BC556-BC546 Sziklai pair) and it worked. Current is 2,09mA by side, though one may have to trim mirror resistor R8 to achieve 0 offset.

The sound, and this confirms Peufeu's claims, became very smooth and relaxed, with soft highs and more prominent midrange and mid-bass (my test speakers are very bright sounding) very soothing experience...the bad news is that the other channel has a problem that I could not solve yet: -27V at drivers bases, without oscillation But, hey! That is the way we learn the most!

I let to the theorists the task of discriminating if this supposed sound improvement comes from increased linearity, from decreased thermal memory or from shared thermal task of units with different thermal behavior...

Time ago I had already tried a mod to the output section that I liked: I cascaded the output BJTs with other BJT power devices (D44H11/D45H11) in common-base. Not properly a cascode, since it is not a common emitter output (even if I CAScaded the COllector ) apparently, but I perceived an improvement in transparency and dynamics. I have also modded another amp, the VSSA, with this trick and I also noticed a worthwhile improvement. My plan is putting, like on the input section, a cascoded CFP output later. You may notice that, absolute and eternal beginners like yours truly, are willing to try mods that reasonable people would never even think of...

Then, I will try the mods to the VAS circuit (cascoded-cascoded VAS) that Peufeu recommends.

But the final goal of all this is to gain experience to attack the modification of my Sony TA5650 VFET amplifier to make a real AMNESIS amp. I already cascoded the VFET common-source output section, which not only make it usable and stable, but also made it a very good sounding amplifier, with increased dynamics and punch.

I hope this humble effort awakens renewed interest in this most important topic.
Cheers,
M.

Hello everyone,
I have a problem with my NAD 3150, that it " buzzes" on the speakers, equally on the two channels, even with the volume at zero and the pre-main sections disconnected. Also in headphones. I did some checks with my digital multimeter and found some AC voltage on all the power output transistors; kindly ask you if this is normal. Thank you

Currently building this crossover Id like to use it for subs.
What Size caps will I use to Have a 20 hz Rollover point?

My tv burned resistor R461 which other resistor number I can use without r461

(Updated schematic here)

I had the good fortune of scoring 10 of these devices in the initial feeding frenzy after someone kindly posted about the and their potential. I shared my bounty with others here on diyAudio and now I want to share an amp that I built with these devices.

I am calling it the Total Domination VFET! TDV for short. TDV means something in my line of work and IMO conveys the giant-killer properties of this device. It has the bass of a powerful solid state amp and the liquid highs that we come to expect from VFET (or DHTs).

Here's the schematic:


I had a lot of trouble controlling the bias on one of the two devices I started with. The VFET needs a Vgs of about -2.0V to -3.0V for between 1 to 2 amps of current. The inductor will provide some of it, which means the rest of it has to come from the bias supply. To provide -1.0V to -2.0V is very tricky. And it needs to be with a somewhat decent impedance. ZM has a very good solution for this problem but I wanted something simpler. The gate draws current and can get into a cycle of drawing current, increasing the bias, and thereby drawing more current.

I tried a LOT of things over the past couple of weeks and tried to make the bias control as simple as possible. This is the result of that exploration. A separate plus/minus supply is needed, but it can be very simple. Center-tapped trafo with a bridge rectifier and caps. From there, 7812 and 7912 regulators are used and they need small caps (10uF) on the input and output. The regulators are very important to maintain a stable voltage. The gate of this VFET draws a small amount of current and some of the parts can be very mischievous. The output of the regulators is connected via a 10k pot and you take the bias from the wiper. That's pretty much it. I ended up with something that is not as simple as I would've liked because it needs a separate supply and regulators, but it is not too bad IMO.

The rest of the amp is very simple. It is a source follower and needs voltage gain from the preamp. I found the sweet spot to be 1.4 amps. I'm sure there are other operating points, but I didn't want to go much past 1.75 amps given the inductor and heatsinking I had. Besides, there is plenty of power with 1.4 amps of bias.

Power up procedure: Bring the bias up very slowly. Use a Variac if you have one. First test the bias supply and set it up for an output of about -3.0V to the VFET gate. Then connect the VFET. With -3.0V on the gate, only a few milliamps will flow. As the gate bias is reduced (towards 0V), the current will increase. Aim for about 66% - 75% of the final bias current value. Then watch it carefully over half an hour or so. The current will drift upwards and should settle after about half an hour. That's the time to slowly increase it to the target. It might move around over the next hour. Check back and dial it in again. Then you should be set.

And that about does it. Note that this is my attempt at making the amp as simple as possible. You can make it even more simple by adding 1.0-1.5 ohms of resistance between the inductor and the source pin. Then the gate bias arrangement can be ditched altogether making it massively more simple. A 10k resistor from gate to ground is all that is needed (in my testing, the mischievous device ran away with anything higher than 10k, whereas the other one was fine even with 47k). The trade-off is that you cannot play around with the operating point and two devices will likely need different amounts of resistance to keep the bias current the same. I think it sounds better without the extra resistance.

Hello, I am new to electrical engineering, but I am competent enough to understand a lot of the basic things. I am trying to fix a Bogen C100 that I acquired, and have attached the schematic provided by the manufacturer. When I got it 2 of the resistors had catastrophic failures and at first I didn't know why, and don't fully understand still. They are R70 and R77 both 22ohms. I replaced those with the same type and value, and when I turned in on, the BJT, G17, burned up. I believe R74 also was overstressed because part of it charred, but it didn't fail completely. It's value is also unlabeled on the schematic and I pointed it out. I got another BJT, a 2SD718 NPN BJT. I replaced that, but I didn't replace R74. I connected everything back, but a connector to another part of the circuit, wasn't plugged in. It was a 3 pin connect that I believe connected to the front potentiometer volume knows and it's board. There is only one actual plug connector, everything else is tab connectors on the main board. From what I remember that should mean that any other boards connect through that boards connection as well. When I turned it on that time, i saw sparks on what looked like the main board near the ac main side, but cant be 100% certain. I checked everything and nothing seem bad, burnt, or otherwise hurt. I noticed connectors between GND and COM as well as between LINK and 4ohm. I was wondering is something was shorted, so I checked for continuity on those connected terminals and all the others to include the 25V, 16ohm, 70V, and right end GRD. They all had continuity with each other, but I don't know if that is supposed to be like that or not. I ended up takeing off the connectors between them and turn it on again, I believe I plugged the 3 pin connector back in. Well the new BJT catastrophically failed and burned a hole on the right side, which may be the emmiter. The resistor that was unlabeled R74 also seemed worse. I measured the resistance of it before and it measured 219ohms in the circuit, but now value starts below that and climbs. I can't read the value because the middle 2 rings are charred off and or lost their color. I don't have a full picture of the internal components right now but but will be able to attach one later. I am attaching everything else I have and an image I found showing those back connectors.

So my questions are as follows;
1. What is the value of R74 supposed to be?
2. What could I have caused to make components fail?
3. Why is the device and components not working correctly.
4. Can I safely test components to make sure they are good and if so how? (If desoldering is needed that's is fine)

I figure it's a long shot but maybe I'll luck out...

If you have a Van Alstine ABX comparator you're looking to sell please let me know. You can PM or email at hardisj @ gmail.com.

Thanks,
Erin

EDIT: Found one. Thanks!

Life has intervened Price reduced!
I am selling my 2 Amp Camp Amp version 1.6 kits from DIY audio store. It includes case, power supply and updated back panels.
I will pay shipping to continental US. Others, we will talk about shipping.
Asking $250.00 each.
Thanks for looking!

Unfortunately, I can't complete my Tubelab SSE project for various reasons. I would now like to offer an already assembled SSE (TSE-II) board.
I can send photos if required.
I ship from Germany. International shipping is possible.

Price: 70€ (approx. 75$) plus shipping depending on the destination country

I have currently ADC in prototype loudspeaker and thinking if it makes sense and is worthwhile the effort to try CDC as well. Anyone who has the experience with both and can describe if there is any difference in the sound? Thanks...

Many years ago, in fact, I had a gold voice E210 E305 series PCB circuit which imitated the board.
I also made some test boards. The result is: if DIY's golden voice, the performance is not as good as the original machine.
Even the LM3886 estimate is not comparable. So I sent the PCB made. Then? There is no more below.
Especially around 2006, the music fax X-A50 is also being imitated and DIY improved at the same time.
Comparisons show that the X-A50, the later DIY version of MX50X2, is much better than the directly engraved Golden Voice E-210 in all aspects.
So later, the similar circuit in Jin's voice did not continue DIY anymore.
In the following process, I also found some reasons for the problems.
Firstly, the circuit of the golden voice is fully symmetrical. This circuit is symmetrical in theory, but in practice, the inconsistency of the components makes it possible to apply it in practice.
The distortion of full symmetric circuit is greater than that of single-ended amplifier circuit.
For example, L series L12-2 L20.5 and music fax X-A50 distortion, is better than the golden voice, Malanz, similar structure.
Later, after a long period of research, in fact, that is to say, when you have time to study it by the way. It is found that the imitation of golden voice circuit should be made directly according to the original factory.
Not ideal, after all, DIY components are different from the original factory.
Some DIY imitations use the same type of components as the original factory, but the brand is different.
More is the use of alternative components. That is to say, no matter the model, brand, or even the parameters are completely different from the components of the factory.
But the circuit parameters are the same as those of the factory.
There are even some field effect transistors, which are directly changed into triodes, but the circuit structure is exactly the same.
This is a messy approach, but many circuits like Golden Voice use JFET MOSFET, and the model is hardly directly available.
So many DIY can't do anything, only to make a messy change, as long as the final success.
In fact, I do not object to the change, because DIY is not a manufacturer, it can not have exactly the same components. But if we make a random change, only God knows the good and bad.
This kind of DIY is in fact a universal imitation of famous machines, not limited to the golden voice. Other imitation machines are also included. This is also inevitable.
Because many components are not available, and even many of them are out of production. And some manufacturers have changed the model of components. For example, the power transistors of music fax are all MF letters.
MF stands for music fax, but as everyone knows, music fax does not produce transistors. The most important thing is to print your own trademark. We can only guess what model it is.
The end result is. Amplifiers from most imitation manufacturers. The actual performance is quite different from that of the manufacturer.
In my opinion, imitation does not need to copy the parameters of the original factory. At most, if the circuit structure remains unchanged, the application of each transistor can be appropriately based on the needs of the circuit type.
Make some adjustments.
Finally, the most important thing is to measure the amplifier. The measured data are compared with the parameters of the original plant, and then improved to achieve the same results as the original plant. It may even exceed the performance of the original machine.
This is a more practical imitation.
Without changing the circuit structure principle of the manufacturer, it is my personal imitation idea to bring the circuit performance of this structure into a better state.
Most DIYERs do not pursue performance metrics very much, and of course there may be no such condition. After all, a tester AP2722 costs hundreds of thousands of yuan.
But we can try to make it in this direction.
Here I start with the original version. Direct copy of the golden voice E210 PCB. I've done a lot before. They're all given away.

Hey folks,

Just starting out on my diy speaker foray and am aiming for a 7.1 home theater build eventually.

I'm intending to do Overnight Sensations LCR, and probably MTM all round. But the problem is while my rear surrounds I can happily wall mount in the corners of my room the left and rights will need to be in-wall.

Has anyone made an in-wall OS build?

Or would anyone be able to recommend a commercial in-wall option that might have reasonable voice matching to the OS MTM I'll have for the other speakers?

Thanks
--
Ben

Over the past weekend at a Hackathon I have designed and printed a small MEH. I used ATH to generate the horn then simmed the HF and measured it to compare. I then also decided to add some midrange 2" drivers to see how it would turn out.

I am so happy with how it turned out for 1 weekends worth of work and not really any simming haha.

On the midrange measurements there is a big dip at around 1350hz the length of the horn is 120mm which would be half a wavelength from inside the compression driver to the horn mouth. Do you think that could cause the big dip at 1350hz then boost (1/3rd wavelength) at just below 2000hz?



The drivers I used were ones that were already here, it was two Faital Pro 2FE35 and a Lavoce DF10.172k which is way overpowered for the midrange haha. The rear chambers were made out of tape and hot glue.

This is the response after processing:



This is the unprocessed measurements:



The following are the polar plots (only up to 40 degrees each way)





Some pictures of the measuring process:

I don't need my diyAudio store F5m power supply board that I received in the recent 100 kits sold.
Will ship first class mail in the USA, for $12 postpaid. SOLD

Hi All,
I was thinking of changing the phono stage to Fet and increasing the gain for a Denon Dl-103. BJTs to Fets K170bl and J74bl. Worth doing? Just a crazy idea? Would need a little guidance of which fet replaces which BJT.

Greetings all-
I've been lurking for a while and haven't posted here. I have two early Amber stereo 70s (black with rack mount handles) that are great. I'd like to use them in mono configuration with my Acoustat Spectra 44s, but one only works in stereo. From what I've read it could be as simple a fix as using deoxit on the stereo/ mono switch, which I'll do. The Spectra 44s are a difficult load and I don't want to stress the amps.

So...I'm looking for good LM391-100 or 391-90 drivers and an actual manual (Hifi Engine show that there is one, but it's not actually there). The schematic seems to be available. Does anyone out there have experience with Chinese made 391s? I'm a bit dubious.

Run as stereo amps, I prefer the 70s to my Eagle 2 and my BEL 1001 and they're basically equal to my buddy's Stax DA-80. Not too shabby.

Thanks-

Harry Z

I'm trying to salvage a small plate amp but the volume control is glued into the front of the cabinet. I've already broken it trying to prise it out.
Any ideas?

Used ~Earthworks Mic Pre-Amp. Some light scratches on bottom (see pics) but overall in great condition. Comes with power cord.

$1250.00 OR BEST OFFER!

Thanks

I recently rehoused my original Aleph J into the 5U chassis, thinking I would take it with me when I move but I cannot take as much as I once thought.

I built it in its orginal form some time back, using DIYaudio store kit parts, scrupulously matched transistors, oversized Antek transformer, original Toshiba JFETs, Russian PIO input caps, military silver plated wire, and a propensity for barrier strips for solid joints assembly and disassembly. However, the damn thing is HEAVY! Note the rear handle/guards and front rack handles for rolling it on its back before picking it up! I do not want to ship this across the country (I once thought I'd palletize it for my move ;-). If you want me to ship it to you at purchase consider it parts as I have had very bad luck with cross county shipping. I would gladly give it over to UPS for pack and ship, I've no idea though how (very) expensive that would be. My price reflects less than a parts cost and does not include shipping.

I live in Traverse City, Michigan, USA 49685.

I built it for keeps but now I cannot ;-(. $600

It's time. I must sell everything. Today I am listing the BA-3 Pre. Like mosts of you I build for myself and have done my level best to create something worth keeping "forever". Oh well, I must move to another country and cannot keep almost anything. Here is a chance to hear a nice one without the expense of time.

I do like that the "warmth" can be adjusted but set it to "neutral" in the end. Funny again, how things go. If you think it pretty, cool, I am told my "dancer" has a strange hairdo, it is taken from an Art Deco figurine. Art is so subjective . $400. I can ship anywhere and I will pack it well but I cannot guarantee it gets through the gorillas to you in good condition. Think of it as parts.

Hi all
I have inherited a Goldmund Studietto in VERY poor shape. It was completely destroyed during shipping after shipper didn't pack it well. I can restore it somewhat, forget about cosmetics and some parts will have to be replaced with home-brewed variety ))) My main concern was the motor. It is a JVC direct drive unit, same as used in QL-A75. I soldered back some wires, and improvised switch connections (since all three switches were destroyed as well). Great news is that it's working. It starts strong and within 2 seconds quartz lock LED lights-up. But there's something screwy with the ON-OFF switch: the normal state is actually ON, so when I put jumpers in the OFF position, motor stops, but my bench power supply still shows a current draw of 60 mA. I remember way back when I was rich and famous and had a Studio, it liked it's power supply constantly on, and it was slightly warm. So I wonder if this is a factory design to keep electronics warm? Or some caps are leaking on the motor control board? Or? Ant advice appreciated, thank you.

For sale are 4 MIFLEX KPCU-01 0.1uF capacitors. The leads have been shortened from the original length.

!!!!SOLD!!! $74 shipped CONUS only with payment via PayPal.

I have a problem with a Goldmund Studietto, the previous owner was less careful with the player and somehow broke the wiring from the arm to the electronics.
Does anyone have a schematic of this device or can anyone give me detailed photos of the wiring in the arm and the electronics?

thank you in advance.

I want to attach a plinth to my Seas Thor speakers in original Madisound-supplied cabinets. See pic. My plan is to use 3/4" mahogany lumber extending slightly past the edges of the Thors. See pic of JMLab speakers for the general idea. Figured I'd attach with six, or even eight, screws into the veneered MDF. Do builders feel I need to use threaded inserts (EZ-Lok style) or could I just screw straight into the MDF? Seems to me that would likely be secure enough; but would love to hear from those more experienced. Thanks.

ALMEDIO is discontinuing production of TEST DISC this year.

Those who wish to purchase it may do so.

https://www.almedio.co.jp/topics/2023/44188/

Hi there,

I know that this will probably be the nth thread about DIY DSPs based on AD chips. After countless of hours trawling the forum for a suitable design that fits a plateamp application I haven't found the one. So I'm taking the chance that someone could point me in the right direction before I bite the bullit and invest the time to design something from the ground up (or modify an existing design eg. FreeDSP classic or Catamaran).

Requirements are:
1 in (mono) 4 out analog balanced via pins for XLR (in) and JST connections (out).
15V power to run off AUX power supply from amp module
The usual features to take advantage of Sigma studio (USBi, monitoring, etc.)
Distortion < 0.005
Optimised layout for platemounting (perpendicular to faceplate)

Anyone with any ideas?

Thankful for any suggestions or leads 🙌

Cheers.
/M

Ciao perdonate il mio inglese sto costruendo un clone del dynakit st 35 riscontro un problema, non riesco a capire sul pin n 6 del triodo di ingresso 7247 ci sono 52 vdc mentre la tabella schematica riporta 112vcc, grazie per eventuali consigli

I have 06 Daytona upgraded system. I have 2 scar audio super tweeters in dash, 2 NVX 6X9 woofers in doors , 2 6X9 5 way pioneers in rear deck. And for subs i have 2 Alpine Type R 12 (grey ones). Dash,door, and deck speakers are amped by NVX VAD4 400watt mini amp. Woofers are amped by Older memphis 1000 watt mono block class D . My issue is im having feedback through my subs. N its pure bass. Been a couple diiferent things from pop when shouting car off, to thumping bass after tuning, and now when rolling Windows up its like a pure bass line. Any ideas? Is it grounding issues or is my amp goin out? Pls help its my fiance car n she loves her stereo system.

Hello all,

I have a peculiar project that I need some insight please.

I own a T10 Shure wireless headset microphone - its cable ends up to a 4-pin (female) plug (maybe the cylinder frame around also acts as a "pin").
I want to connect this microphone to another microphone that I own. The latter is a typical "cone" microphone that when I unscrew the top part, I can see the microphone as well as only two cables connected to it.
My project is the connection of the T10 Shure to the cone microphone but:
1) I don't know which 2 pins of the T10 Shure to connect with the 2 cables of the cone microphone
2) I don't know if this project makes sense anyway in terms of quality of sound achieved

Any input more than welcomed!

Thanks in advance,
Al

Hi All,
Ever since joining this forum class B auto-bias has been on my mind. Thanks to Russel Kinder's RK-Auto200 design.
Russel helped me along massively in solid state design when I was a newbie here. Only at the time I couldn't make sense of his autobias schemes.

Yesterday I think I finally conjured up a circuit that does the job correctly.

I set out to find a circuit that:

• Replaces thermal tracking. Forming a subsonic bias feedback loop that compensates for thermal drift.
• Maintains the bias current even with full power 20 Hz signals.
• Should bring the bias up, such that before the bias feedback starts acting there is no bias current and all remains safe.
• Leaves no signs of its presence opposed to a passively biased output stage.

Looking back it turns out to operate pretty much like the RK-Auto200 design: (which definitely primed my brain)
https://www.diyaudio.com/community/threads/rk-auto200w-amplifer.367674/
who got the framework from Wlliam Chater:
https://www.diyaudio.com/community/...ontrol-for-power-amplifiers-revisited.367386/

The Framework:
Sensor Circuit -> Peak Detector -> Integrator -> Bias generator

What really cracked my brain was howto detect the bias current under large signal conditions.
It is known that the class B signal currents cross at the bias current. So some circuit should measure what current is present when I(R24)=I(R23).
I guess this is what is referred to as "Zero Crossing Detection".




Yesterdays contraption seems to pull it off:




Two current mirrors Q37 to Q42 forming the sensor circuit sense the bias current through 0.22ohm Rsense.
The top mirror subtracts I(Rsense)*Constant from I(J3) while the bottom mirror adds I(Rsense)*Constant to I(J3). This constant is set by by Re and Rsense. The output currents of the two mirrors are added onto Rc to create voltage V(Rc) which is proportional to bias current (and signal current).

Current mirror output currents Ic(37) & Ic(q38) summed to I(Rc) creating V(Rc):




Now under class B signal conditions the magnitude of the V(Rc) peaks are proportional to the bias current. (some kind of personal revelation to me)
This is where the peak detector comes in. I've tried single and dual opamp active peak detectors, all left some artifacts in the FFT. Passive does not. So I Simply implemented it with D11 and C11 to create V(vpeak):




Next V(vpeak) is fed to an integrator (U4 TL072) that compares it to reference voltage Vset. In this case -4V, being the target voltage for Vpeak.
Now the bias current can be defined by Rsense, Re, Rc and Vset. Rsense Re and Rc set the gain of the current mirror sensor circuit, the integrator should make all the rest irrelevant.

The integrator then drives an opto-coupler to engage the bias-spreader. More opto-current results in more bias and no opto-current results in no bias. This should be true even when the output stage is getting boiling hot.

Now the loop is complete and it seems to be pretty sturdy but I'd like to make it sturdier. Unfortunately the bias does drop (10mA or so) when a 100W 20Hz signal kicks in. It never quite gets back to where it was but at least we see integrator trying to bring it back up:




Then there is the issue of loop stability. Depending on the Gain of the sensor circuit, the integrator time constant and C11 (probably many more), very low frequency oscillation may occur. Its damped ok now but id like to know howto properly compensate it. I haven't figured out howto do proper stability analysis on this.


The integrator output current in response to large Low F signal:




The output current dropping indicates the integrator thinks the bias has gone up so it drops and we loose some bias. It seems to still misinterpret large signals for bias fluctuations but only a little bit. The loss of some bias current I attribute to the non-perfect Sensor circuit and the passive peak detector. Perhaps there are other causes. Perhaps it needs one more op-amp after all. Perhaps this is accurate enough. Most important is that the bias doesn't keep falling or shoot up like many of my other tries. Neither does it leave anything sign of existence in FFT's.

Hopefully I can breadboard this in the following days. I'll probably waste more time simulating and considering:

• Sensing from the Emitter resistors opposed from collector resistors and making the circuit float with the output.
• Eliminate the opto-coupler and use Q19 and Q20 current sources to control the bias.
• A transistor based Integrator

As always,
I'd love to hear your thoughts,

Cheers
Ruben

Is anyone here looking for JBL d2415k driver ? I have here 2 pcs for sale , box opened but never been use

I'm new to the forum although been registered for a few years, I never actually posted. I need to post a few things for the moderators which is fair enough.

I am about to fit a replacement OLED screen for Naim NDS - thought it might be worth asking if anyone on here has done the same and is there anything to be careful about? Many thanks.

Hi,

I'm planning to make BT audio using one of the mentioned modules.
Is it possible to get song info using UART or any other interface?

Installed this amp with 2 -12" kicker subs and found that it will cut out on certain songs when the lower frequency hits. Thought it was needing more power so hooked up a 3 farad capacitor and still having the issue. I have the speakers bridged and have messed with both the frequency and the gain but get the same results. It doesn't cut out when turning down the gain but then I lose the desired bass. Something not hooked up right or is the amp possibly bad?

Wonder which speaker is this?

Dates from the seventies.

DIY type or some commercial one?

Looks like a big middle tone horn with two 12 or 15 inch

If you are interested for measuring and studying the vibration behavior of any audio component like a loudspeaker driver, a loudspeaker stand or a turntable you could use an accelerometer with a suitable amplifier.
You could find more information in my article in Audioxpress June 2011 which is posted also online here:
Test Your Speakers? Performance with this DIY Measurement System | audioXpress

If you are interested to construct such a system you could find information here:
http://www.diyaudio.com/forums/swap-meet/262944-pcb-anf-front-panel-accelerometer-preamplifier.html

Behind this schematics stands an idea to try using SIT transistors with triode-like output characteristics for simple preamp design. The common source stage based on KP926A Russian SIT transistor is used for amplification (nearly 20 dB) at 100V power supply voltage and 175mA quiescent current, class A operation. Unfortunately, KP926A has 1600pF of Ciss (instead of this transistor much better would be SONY 2SK60 which have Ciss = 190pF). To handle the 1600pF of input capacitance of KP926A one needs a buffer stage, which I decided to make like well known j-fet follower with 25mA quiescent current and plus-minus 15V supply voltages. One needs a decent j-fets for such a buffer, like for instance CP650. In my case I used Russian KP601A, which is close to CP650. The Ciss for KP601A is 6pF. Before this buffer a simple volume control based on 10kOhm ALPS resistor stands more than comfortably. In fact, I used a voltage divider constituted by 7,8kOhm low-noise constant resistor and the variable part of ALPS below it. Capacitors used include Elna Cerafine, Mundorf polypropylene etc. This schematics has no NFB, its output resistance (measured by immitance meter) is 200 Ohms. I compared it sonically with the good Parasound JC2, which has only 60 Ohms output resistance. Power amp was 50W version of Pass Zen9, Shanling CD T-1500 player, speakers are Paradigm Studio 100 v4, cables Stereovox (speaker), Nordost (interconnects), power is provided by PS Audio Power Plant Premier. I can say that I love my Parasound JC2 very much, but in this comparison SIT-preamp sounded more musical. It gave more detailed and pleasant low-mids and the bottom end. At the beginning I thought that SIT-preamp has lower output resistance than JC2, but it is not. So, I do not know what a magic stands behind it. Speaking about transparency of highs the two preamps are very close, in some cases maybe JC2 is a bit better (difference on the level of tiny cabling effects), but JC2 is connected to XLR outs of Shanling (known of being better) on contrary to RCA outs for SIT-preamp. I would be grateful for help in understanding what a “devil” is behind this SIT-sound.

To use a low cost low noise high Hfe bc550C/560C as pre-drivers, I float them with a bootstraped supply. The result compared to Wolverine 3EF with single pair outputs is higher impedance and lower distortion.
These are measured with 1Mohm source 20ua 1khz input vs 22ua for Wolverine.
The biases are adjusted for minimum distortion 0.068% vs 0.31%.

That’s really nice performance at around 15 degrees off axis if you consider the above zero and 45 plots. A parallel pair of the 4” version with one being used with a .5 coil for BSC would be a nice compact speaker
https://faitalpro.com/en/products/LF_Loudspeakers/product_details/index.php?id=401005105

Has anyone else had a bad soldering day? I had to walk away yesterday, because my work was crap! Today, all is going well though.

So hello everyone i am new to audio so i have some doubts regarding subwoofers:

•If i have two subs with different sizes or cone area one with 8” and annother with 10” but with same sensitivity ie 90db at 1w/1m and same rms power 200w and same xmax then what is the advantage of 10” over 8” sub?

I did I gave away the old analog scope that I had for almost 20 years when I moved.
So when it came time to re-set up my bench I looked at the modern scopes, and it's amazing
to see what even a new digital budget scope can do as compared to an older analog scope.

So if you are looking for a scope you may want to take a look at the new digital scopes.

But I will say if you have an older analog scope now you may want to hang on to it
if you have room for it since they are fun to play with for oscilloscope music etc.

Good afternoon everyone, on this occasion I am urging you to repair this Kicker brand amplifier model ZX1000.1 REV 2.1. At the beginning, damage was found in the power supply, it has already been recovered and in the output stage there is an auxiliary supply that was damaged, the 2 htp18n06g were replaced and the 1n4002 diode is already oscillating, but now I have stopped at the driver card, I already managed to get it to turn on and stay on, I don't have any pulses in the output fets, I mention that I have the fets outside the board since if I leave them inside they won't stay on, greetings

Hi, i have a 2005 Cadillac STS. I just hooked up a Dual 1000w amp and the fuses in the amp keep blowing as soon as it gets power. Dont know what i did wrong.

I'm using the F5 build guide to put together an F5 v3 amp and I can see that 12 comments have been posted, but I'm not able to see the comments themselves. I have a faint memory that some of these comments were very useful, and I found them useful when building the Amp Camp amp. Am I doing something wrong? I tried different browsers and am signed into my diyaudio store account. (Sorry if this isn't the right forum for this question).

So a fellow member of an astrophotography club I’m in shares my passion for hifi but not the time or ability to DIY and in some deep conversations, I’ve convinced him that we can outdo his Sonus Faber Strads for around 1/10th the cost. He’s paying for the material and absorbing the airfare for our summer photo trip to Utah as a gratuitous bonus for design and labor!….not a bad deal for him! Lol

Promises fulfilled, ……..we’ll make his floor plan more open and his wife happier by replacing the obnoxiously fat body Strads with a tall, slim enclosure only 6.5” wide and 18” deep. Folks here who know me also know I firmly believe that narrow baffles are the ultimate in stereo imaging…..once you’ve done an A/B comparison where the bass response is fairly similar, I don’t think anyone can go back to wide body or offset monkey coffins.

The initial design thoughts are 4 Dayton Signature 150mm midwoofers and a yet to be decided on AMT tweeter. The alignment will be top and bottom midwoofers with a .5 inductor to offset BSC and ported for lower extension…..the two MM midwoofers will be high Q sealed for some midbass slam in the 100-200hz region…….I don’t voice my designs for a flat response……flat is boring

If I choose a high efficiency AMT, we’re right around 95db with this system…….not really required in his case as he’s got some expensive Danish power amp that looks like it belongs in space capsule instead of his home ( the power cord is thicker than the wire that comes into my house!) Secondary hopes is after hearing this, he can ditch that and enjoy the warmth of a nice pair of monobloc tube amps.

What’s your thoughts?……..his space isnt huge at 15ft by 25ft and serves as a media room. He’s already got a pair of REL subs he says he uses them only for movies……turns them off for 2 channel. I’m unfamiliar with commercial subs so I can’t speak to them other than I thought they sound pretty good. My proposed design should have an in room F3 around 45hz……….not nearly as deep as his Strads but I’m hoping to convince him to use the existing REL subs to supplement them……this will take some convincing as he’s more of a hifi purist…..too many years of brainwashing back in the day when we dived through the pages of glossy HiFi mags.

The Jackson is my first tube tester. I just bought it at auction for $20 and it works!
I need to test several 829b tubes and of course it has no 7-pin socket or testing parameters for the 829b.
My "logic" is to fabricate a pair of octal to 7-pin adapters and then select a pentode from the Jackson's parameter list which seems most similar to half of the 829b for testing:

• a pair of sockets to test half the tube at a time
• The curves for the 6L6 look very close
• the objective is not accuracy in testing, but balancing of tubes, so use of similar tube parameters should work in spite of not providing results

So my questions are:

• are there pentodes closer in performance parameters to one segment of the 829b than the 6L6?
• is a pair of adaptors overkill? could I just fabricate one adaptor and move the anode connecter from one side to the other to test each element?

Hello to all on this site. I just purchased an Alpine 3502 and can't get it to turn on. the amplifier only has a din connection for the input. it only has 3 yellow wires. black and red ....the power and ground are 10 gauge and the smaller red wire appears to be 18 gauge. do I need a signal from the radio to get this amplifier to turn on? ...any help would be appreciated.

In servicing this amp, Im not finding proper +-15vDC on preamp components. im unable to determine where to start actually. What components are responsible for housekeeping voltages?

The amp powers on and idles at 1.5A. No passing audio. Looks like the Class-D section and PS is ok

Thank you

Replaced with new components replaced protection circuit. Amp does power up but only 9640’s are with half signal. Audio is distorted. Need some help with further diagnostic on this amp…

Hey all,

Got my hands on Pioneer GM-D8601.
Someone else tried to repair it before me but didnt succeed. Originally it had both psu and output blown. New fets have been fitted along with buffer transistors and drive ic. Psu section runs well but the output is problematic.
When CSD cap is installed it swings back and forth between protection. When i remove the cap amp powers up, output starts switching, draws excessive current and fets heat up, also there's ~2V dc offset on output terminals. I did my best probing all the smd transistors and diodes near the drive ic but cant find anything wrong. Drive wave looks a bit off but for me the switching frequency looks a bit high? Also when i have my rca connected i dont seem to have any signal on pin 3(in) of IRS2092.
Anyone have any ideas of what to check next?

Thanks.

This will document my build of Pete Millett’s DCPP “Engineer’s Amplifier”.

I have 2 Antek 230v toroids to use for B+, and series boost at the output tube plates. I’d like to have this boost on a switch, but biasing might not work out that way.

There’s another small Antek for the bias supply.

I have Edcor CXPP 100 watt 3.3k output transformers.

Currently have 6HJ5 output tubes, but really want something taller with a plate cap - this is purely for aesthetic reasons, but that is important as this thing will sit in my living room. Very open to suggestions on tube choice. The transformers are quite large, and I would like to put covers over them, which will make them look even larger, and the tubes will look a little sparse and small next to these.


Is it ok to stack the toroids like this? They’ll be under a cover and secured properly.

Looking for opinions. I'm a new owner of a Denafrips T2 DAC. Interesting piece, what is also interesting is their choice of WIMA caps. MKS from what I can tell are used in the filtering section, and I think FKP on the output. I've had mixed to poor results with WIMA polyester in the past, maybe in the filter section they might be ok, augment/bypass the electrolytic bank, but on the output and/or coupling the DAC resistor ladder, I would have chosen different if I were designing maybe.

Interested in opinions. I was looking at some Charcroft Audio Silver Mica as a possible FKP replacement, fitting MKP will be tough and wouldn't want to make a mess of it visually. Some polys in the filter section would have been nice, what are the thoughts on this? It's as good as it gets with WIMA MKS/FKP?

Looking to build the Nelson Pass AB100 which uses TIP147 / TIP142 Darlington Complementary Silicon Power Transistors.

How important is it to match transistors?

What parameter should I be matching and how close should they be?

By what means do I take the measurements?

Any other hints about transistor matching?

Thank you,

David.

Hi. I' m investigating the Masterclock subject and in preparation for some more advanced design I started with the already nice one from Paul, and he based his design on the work of Gertjan Miedema, see the project blog for details. ''Paul's DIY electronics blog_ Building a 10MHz Master Clock'': https://www.paulvdiyblogs.net/search/label/T&M

Paul shared his pcb gerber I had made 5 pcb that fit the specified enclosure. I also had made the enclosure front panel. Since the gerner couldn't be edited, and I wanted Gertjan OCXO heater warning leds, I made a small pcb that you can easily installed on Paul's one to add this function. I confirmed that the Gerber produced pcb and front panel that fit perfectly the recommended enclosure.

Since I have 4 extra PCB sets, I'll sale them at my cost of 10U$ for main PCB, enclosure front panel and small OCXO heater monitoring PCB (the red one) + shipping cost and Paypal fee.

I made a detailled BOM, found all the needed parts (Oscilloquartz 8663 OCXO, enclosure, etc) info and will share that with you if you decide to buy the set.

Let me know if interested.
SB

Are these usable for an amp?

I have a Crate Gt 80 that is cutting out like many people have posted. I ran a patch chord from line in line out on back of amp and this works. Has anyone with this problem and patch chord solution figured out what is wrong. I have put a new input Jack and two Zener diodes that didn’t fix the problem. Running the patch chord work doesn’t cut out with patch chord. So many people have had similar problems with these amps the solder connection on the board look good no burn marks. Thanks

This thread is a compilation of photos and posts of my F5 build. My original thread became so popular (and chatty) that the photos are spread over many, many pages. To save you the trouble of paging through 500 posts, here it is in one place.

The original, if you are interested -- http://www.diyaudio.com/forums/pass-labs/182723-how-build-f5.html There are lots of neat questions and answers in that thread.

LOTS OF PHOTOS. IT WILL TAKE TIME TO LOAD THE PAGE.

Nothing out of the ordinary, Peter Daniel boards, single transformer, Tech-DIY transistors and other bits, HiFi2000 chassis.

I have collected all the pieces and finally today the chassis arrived from Italy! I am ready to start!


This is From Modushop.biz, it's a "Pesante Dissipante 4U depth 300 mm" (6 1/2" tall x 11 3/4" deep x 19" wide) Which will have a different specific number depending on color and faceplate thickness. I needed to get the shallow(300mm) case, if you have the room for it, you could get the 400mm deep.




Here is the obligatory "armory" photo. Only one of the amp channels shown.


The rear panel. I thought I ordered an Inlet Module with a switch, but I didn't read the datasheet well enough, and it has a neon light power indicator instead. Oh well. Luckily I have a couple of nice bat-handeled switches, I will use one here. The Jacks and RCAs are also from my box, I think they are Vampire.


Here are the contents of the Tech-DIY F5 kits, the Peter Daniel's boards, and a couple of silpads.




The PSU components. Vishay rectifier blocks, Peter Daniel PSU board, resistors, 33,000uf capacitors, CL-60 thermistors, and a big-honkin' 600VA transformer.

When I was determining the transformer size necessary I must have had a brain-sneeze, I must have only thought of one secondary! Oh well, it was only $20 more than the 'proper' (400VA) size. The 4-pin caps will work on the board with just a bit of modification.


If you were wondering, the Peter Daniel boards are very small. Also very nice!

As mentioned earlier I needed to get a few more things before proceeding with the build…


Specifically, wire, connectors, standoffs, spacers, and a tap set. (also a couple of other things not photographed.)


As I am not exactly sure what will be the best standoff/spacer, I bought an assortment. Brass, Nylon, and 'real' 6-32 thread standoffs. Also shown are the 1/4" connector spades, the 6-32 bolts and fender washers for mounting the power transistors.
Also note the Power Inlet module now has a switch!

Not photographed is a big pile of 4-40 hardware for mounting the boards, as well as a few more 6-32 bolts for the rectifier blocks and barrier strip.


The store I went to didn't have taps without the drill bits, but since they are the exact size for the tap, I didn't see any disadvantage in getting them.


Trying to detemine the best layout for the bottom panel. The Transformer is positioned in the front of the case.



I like this better, it will lead to more symmetrical wiring. Which although not necessary, appeals to me.

If I had the 400mm deep chassis I would also have the power inlet and the barrier strip on the centerline.

I think it is a good idea to leave the chassis vents unobstructed, to keep the heat exchange/airflow as good as possible.


Today I got some drilling done. A lot of effort with not much to look at...



This is the amp board and the 2 power transistors. They will be mounted to the middle of the heatsink.


Once the hole locations are marked, I made some starter holes with a set punch. The 4 in the middle will be 4-40, the two on the outside 6-32


Drilling. Wear safety glasses!


Drilling complete.


My friend was kind enough to tap the holes.


Pilot holes for the RC jacks and Speaker posts. Also the beginning of the IEC inlet module cut-out.

I have all I need in place to build the amplifier circuit and mount it to it's heatsink -


Here is the heatsink, with the holes sanded smooth and cleaned with rubbing alcohol to remove the last oil and sandings/shavings.


Here is the hardware, 6-32 bolts and fender washers on the transistors, brass spacers and 4-40 bolts on the board


A dry run, to check fit.


Spacing looks good! Now to complete the board...


Stuffing the board. Have your meter at the ready and measure everything before soldering!!! It will save headaches later!!





OK, the board is stuffed and the wires attached. My color coding is as follows;

Black - ground
Blue (V-)
Green (V+)
Red (+) out
Red/black twisted pair in orange jacket is input + and -

I like to have the wires much longer than needed to help facilitate neat and tidy wiring later.


On the heatsink with silpads attached.


In this photo you can see the following -

The thermistors are not bent down yet, as I need to get some loctite for the threads before I am actually done... Same with the transistors, they are not soldered and trimmed.

The two 3W resistors on the outside of the PCB (R11 and R12) are standing up off the board so that when it becomes time to set bias, I can easily connect leads across the resistors.


Here is the terminal block showing the thermistors and the capacitor.


Marking the chassis bottom for the PSU board, rectifiers, and (not in photo) the transformer bolt.


Rectifier block


The monster Antek AN-6218


Stuffing the PSU board


Remember to connect the grounds... Peter Daniel suggests you do it here. I am not sure if you need to have 2 jumpers like I am showing, but a good, low-impedance connection is always a good thing on a powersupply.


I mounted the bleeder resistors to the bottom of the board. You probably could do it on the top if you had physically smaller caps.


One thing that needs to be checked is if the spacers are taller than the bottom components. Looking good!


I needed to hold my camera upside-down to get the flash in a place where it could illuminate the bottom. This shows that there is plenty of room under the board.


The capacitors I am using.


These are a 4-pin cap, and so the unmarked (and unconnected) pins need to be trimmed off.


These caps are a bit big to be mounted just by two solder pins, so I am using just a small dab of silicone on the case to help stabilize and support the cans. Also note that the unused pins are now trimmed.


The silicone


The complete (except wires) PSU board.

Wiring the PSU -


The primaries attached to the barrier strip. AC from the power inlet module will attach to the center two connections of the barrier.
Note the rectifier blocks -- the notched corner is "+" DC, it's opposite is DC "-" The other corners are AC in.


The leads of the secondaries connected to the rectifier blocks. Here you can see the AC connected to the AC in tabs of the rectifiers.


PSU board connected to the rectifiers.


The PSU completed except for AC in. This will be from the power inlet module. The black leads at the center of the PSU board will be the speaker negative connections.

Let's look at the PSU schematic just to make sure everything is OK... Remember that I am wiring it for 120v operation, so the transformer primaries are in parallel. People wiring for 240 with a transformer like this, please ignore.


Notes in red are mine.

Look at the connections of the transformer primary, through the thermistors and line cap, to the mains.

Hot AC is connected to the "120" (which in my case is the red leads on the primaries) One red primary is connected to AC hot through a thermistor.

Neutral AC is connected to the black "0" leads, one of which is connected to the AC through a thermistor.

AC Hot and Neutral have a cap across the leads.


So, yes, the AC will be connected to the center 2 posts, which is across the cap.


Left to right we have post 1, 2, 3, 4

POST 1 - Transformer primary 'B 0' which will be connected to AC Neutral at post 2, through the thermistor between post 1 and 2.

POST 2 - AC Neutral in (not shown in photo), connected to Transformer primary 'A 0" , a thermistor to post 1, and a line cap to post 3

POST 3 - AC Hot in, connected to transformer primary "B 120", thermistor to post 4, and line cap to post 2

POST 4 - Transformer primary "A 120", connected to AC Hot through the thermistor to post 3

If you look at the red and black wires in the photo you will see that the Mains AC must to pass through a thermistor to connect to each of the 2 primaries. And that is the point of them, to keep inrush under control during powerup.


UPDATE - (This is the only place I can edit this thread) Please look here (post #401 if this thread) for the new, much quieter grounding scheme -- http://www.diyaudio.com/forums/pass-labs/188691-illustrated-guide-building-f5-9.html#post3161231

I have some NOS Jensen copper/paper/wax inductors after an abandoned project.

6 pcs 3.5mh 12 AWG
2 pcs 1.0mh 12 AWG

All unused.

They are sold as Duelund Wax copper foil now, at a cool £392 pcs for the 3.5mh and £229 pcs for the 1.0mh.

I have no idea how to price these, so send me an offer if you are interrested.

I am looking to build a modern DAC with USB as well as optical and/or coaxial input and the ability to handle a wide range of input standards - but primarily 44kHz 16-bit for now. My aim is to play with better power supply, clock and output stages. I don't want to spend too much on my first attempt but I am aiming at better than just good sound quality. Ideally I wanted current-output DACs so that I could do my own I/V stage (discrete or quality transformers). Most are voltage output except the ES9038.


If anyone has experience of any of these boards then I would like to hear about it. Buying from China on eBay always runs the risk of fake and/or QC-fail parts being used, hence my interest in real world experience.

Any recommendations for current-output DACs that I haven't yet been able to find on eBay also welcomed. These seem pretty hard to find now.

Thanks in advance.

M

My brother has obtained a pair of Dave Berriman DBS6 bookshelf speakers. They use a proprietary 8" woofer and a Morel MDT30 tweeter. The design for these was originally published in Hifi News and Record Review. We have a scan of the article but it's unreadable, including the date of the magazine. It looks like February 1992 but could be anything really.

If anyone knows the issue these were published in, that would be very helpful. Also details of the crossover, as there a couple of strange things going on that look as though whoever built it originally wired it up incorrectly. Ultimately we will do some measurements and do a design from scratch but a good starting point would be useful.

Thanks for any info that anyone might have

was fooled when purchasing this Yamaha CA 1000, the two internal metal covers are missing, I'm looking for help, thank you

Hi there,
I recently acquired a Rotel RP-3000 that I'm having refurbed and had a question on higher-quality panel mount connectors.

I am sending the tonearm out to get rewired, and it's wired to old panel mount RCA's and and 5-DIN connector. Is there anything "better" out there? I found a Neutrik 5-PIN female panel mount connector, but I have no idea if that's an improvement on what it already on the turntable. Cardas makes 5-PIN DIN connectors, but not in panel mount.

Also looking to get some copper/gold-plated RCA's, but I can't seem to find those in a panel mount option.

Thanks in advance.

For sale 4 KEMET ALS70A capacitors, screw type. ESR 14 mOhms
These have a life of 18000 hours at 85 degrees
Asking $100 plus shipping for all 4.

I want to measure specs on a preamp. I have a computer based analytical system so I can measure output, distortion, frequency response, etc.

But, what about an output load. Shouldn't the device be under some load while under test? Perhaps it should be connected to an amp with is connected to a dummy load.

Large Variac that can handle up to 6.3 amps. In a metal housing with handle, earthed plug and socket.
I include a large panel meter (96 x 96 mm. class 1.5, soft iron) that can measure up to 250 VAC.

Furthermore, with signs of use. Has been tested and works well (except for the built-in display).

Weight including packaging is over 10 kg.

Price : EUR. 145,= + shipping

Purchase link : https://www.hood.de/i/stelltrafo-variac-0-230-v-1-45-kva-6-3-amp--116893478.htm

8 pairs of 2SJ56 / 2SK176. Respectively they have the same date code.

Only sold as a lot. $25/pcs, $400 in total.

Registered shipping at cost.

Ships from Sweden.

Regards
R

Hi,
While cleaning out a cabinet I stumbled on the receipt of my Seas Odin speakers making me aware that next month they are eligible to celebrate there 27th birthday. It made me remember it was time for there yearly cleaning using a tiny bit of water and a tiny bit of soap. While the drivers are still performing fine I did notice that the rubber surroundings, while still flexible, feel a bit different from what I remember from years back.

So I wonder is there anything I can do to prevent further decay of the rubber? I read that some people recommend glycerol, but others believe that it only provides a temporary improvement after which the decline increases. So looking for some quality advice.

I love to keep them drivers for at least an other 10 years.

I have TI/National Amplifier ICs which I am offering for sale

3 × LM3876TF - 6EUR

All devices are completely unused. Guaranteed Genuine IC.

payment by paypall+ paypall fee+ shipping.

Hi all. There's a lot of posts in this forum with noobies like myself asking basic questions about test equipment. Would a sticky that outlined general recommended specs be helpful? Maybe a "Good / Better / Best" type of thing, maybe? Surely folks can understand how daunting it is selecting equipment when starting from zero? We understand it needs to be good, but how good? Not like "this cable sounds better than this cable" good, but "don't buy this function generator because the THD is too high for amplifier testing purposes" type of good.

This looks like a fun project, anyone tried this clone from eBay, it looks like first class pcbs

I find this to be pretty loud but for uncompressed (raw live instruments), I'm finding it to be not so useful because transients seem to shut the amp down temporarily. Is there a way to turn this protection off?

I'm new to using oscilloscopes and wondering why I see a double line at the bottom of the wave. It happens with my function generator connected, but also with the built in 1kHz probe tester connection on the oscilloscope. Same result with different probes in different channels, also with the same probe in different channels. Probes have been calibrated. 1x and 10x give the same result. Coupling is DC, trigger auto or manual or single all the same results as well. Please see screenshots below:

I bought it for 20 euros and have recapt it because they were leakey.

when dip switch is in STEREO mode it shows BRIDGE on the display
when dip switch is in BRIDGE mode bridge it shows PARALLEL on the display
when dip switch is in PARALLEL mode its shows BRIDGE on the display

left speaker output chanel works but not right speaker output chanel when I have dip switch in stereo mode.

I think it could be some ic that is connected to the display and the dipswitch that has given up?
Anyone know what this could be?

A cool little Variac to grab for cheap, the auction is on Ricardo. Weight is ~5Kg so makes no sense to send elsewhere, sorry.

Hi all -

Continuing a discussion found both here https://www.diyaudio.com/community/threads/the-mysterious-danley-crossover.364891/ and https://www.diyaudio.com/community/...eh-synergy-project.409866/page-5#post-7631790, opening up a dedicated thread (in violation of @Patrick Bateman's first rule of Danley fight club) to discuss the potential sound quality benefits of an external crossover on an SH50 vs their stock passive crossover on recent models. I realize this question is probably best fit to discuss with Danley themselves (and I've asked), and I realize this isn't really "DIY", but since there seem to be a good amount of members with direct experience with the SH50, I figured there could be some nice discussion.

Overview: I'm leaning towards a Danley solution for home audio, 2 channel mainly. I've tried several other highly rated (ASR) speakers but they don't seem to be getting me closer to a "Berghain in my living room" sound that I want to achieve. So, time to try an actual PA. I like Danley because I've heard them many times in a club setting (pretty much every new club in NYC is kitted with Danley these days), and the Synergy design promises great results when it comes to side/back wall reflections. Plus, they'll hold their value much better than most small-brand hifi speakers.

My choice is now between a boxes with passive crossover, or tri-amped ones built for external crossover. I'm concerned only with sound quality, not resilience. The question: are there known shortcomings with the SH50 passive crossover such that better sound quality in some dimension can be achieved going active externally? Assumptions: I'd be running the whole thing through a MiniDSP w Dirac for holistic room correction, so presumably this would take care of in-room frequency response. What's left seems to only be phase issues on individual drivers. Are there other aspects to consider?

Given the complexities of building passive crossovers, there must be some residual tradeoffs that Danley have made for their crossovers. In experimenting with these boxes, has anyone noticed what these tradeoffs might be?

I got a kicker IQ off a friend who had parked his vehicle and had to retire from driving. I had some kicker products back in the 90s so I was excited to have a what I thought was a familiar amp. And even though it was something more than I really needed I jumped through the hoops and set it all up .. sounded great until that dreaded moments of having to jump start my vehicle I used a Makita 18 volt cordless drill battery to jump my car which I had done many times before it seemed to have affected the app right away and it had overcurrent now I've taken the amp apart I am by no mean a scholar and small electronics and I'm going to hopefully be able to put some pictures in and maybe some of you much smarter men than I can let me know if you see any problems in these pictures
#1 not sure if any problem there but looked a little burnt maybe
#2 top view of the two issues I'm sure it has
#3 so okay so I'm going to sound like a kindergarten student here now but anyway I noticed the amps got like coils on one side and then the other side is there isn't any coils haha anyway there's like a fence that defines someone so I'm going to call it a fence long beside the fence is in picture number three there seems to be something that blew up and something melted I don't know what the f*** those are I'm sorry for my language but anyway I'm hoping that maybe someone could tell me what those things are and if they actually are fried blown up disintegrated melted nfg
#4 and in the fourth picture there I don't have things called now either I did remember before now I don't remember but anyway that definitely looks like it's got some melt off to the side I'm pretty sure anyway so yeah my absent protect mode it won't come out of protect mode I tried checking with a multimeter different things that were grounded and and with the you know the positive to areas it seems like the power and continuity and different spots that it shouldn't have I gather is probably more to it than I can see with my own eyes I don't know if I can get any help or even knowledge of where I should send this app Canada if anybody has any ideas thank you very much for any help

Hello all, I have come to a point in my 2.1 project where I need to replace the current 7" driver with the smallest 40hz setup. Available power is 140wrms and there is variable bass boost

This is for very intimate night listening, so think low volume with loudness button on

Driver needs to have a mounting depth of less than 70mm. Any suggestions?

For sale a pair JANTZEN JA 8008 (Troels Gravesen )
they are newer used and with black faseplug

2 used comes for free ( one ok another is rep, but works )

more picture here https://www.dba.dk/hoejttaler-andet-maerke/id-1111399843/

price 362 euro plus delevery