Well i checked the synergi patent Thomas has



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It's says expired at the bottom?


I'm just wondering what this means? since I've seen alot of people talk about how companies aren't allowed to do anything like that etc

Hi there,

I'm looking for a replacement for a blown Focal TC90TDX tweeter. Anyone on the forum got one spare they're willing to sell??

If not, wondering if there are any equivalent drop in replacements peeps here would recommend for me to buy a pair?

http://nedlab.com/wp/wp-content/uploads/2014/06/Focal-TC90TDX.pdf


Any insight is much appreciated, thanks!

Interested to know of commercial solid state amplifiers, i.e. not kits or home brews, with no loop NFB around the output stage. I was researching the Dartzeel (again) and found mention that this has been done else were, NAD and Tandberg were mentioned but no model numbers. I would like to exclude Quad current dumping type amplifiers as well. Would be nice to fill this out a bit.

to start the list:

DartZeel NHB108
DartZeel NHB458

Good morning!
I just bought a used AKAI AP-103C turntable. I thought that I could build a phono preamp myself without doing my research before buying the turntable.

I am not really an audiophile I just want to listen to my records. Is there any simple schematic for a phono preamp?

The basic problem that I encounter is that most schematics need +-V and ground meaning that I have to use a center tapped transformer that I CANT FIND IN ANY ESHOP in greece. Shops are closed because of covid. So I only have access to eshops and my stock of components.

If it's possible I would like a TL072 schematic (because I have a couple of them). I don't even care if it has eq or volume knobs.
(I have experience from copying effect pedals so I can transcribe schematics but I am not that experienced in understanding them)


Thanks in advance!

Hello, somebody knows how i can calculate the Q of a quarter wave resonator (a tube with one open end), without measuring it ?

Im looking to do 1/4 wave resonator array for absorbtion so i would want to be able to test different configuration without having to build them each time.

thanks a lot !

Hi,
Anybody knows where are XMOS chips? They are gone for more than a year now. I thought to build usb to i2s on that chip, but looks like impossible for now. Is it a chip shortage or something else? Will they come back? Looks like nobody knows nothing about that according to google🙂

I also have a surplus of 10pcb, the price is only about $3/pcb. I can free as gif for anyone, you only have to pay the shipping cost. But I don't know the shipping method outside Vietnam.

I bought a quad of 6P3SE/6N3cE to try out in my Mcintosh 240, as I heard it was a good tube for the amp but I see the tubes have six rather than seven pins and all of a sudden I'm worried I need to do something to run the tube in it... or, plug it in and have my beloved amp burst in flames.

Can someone confirm for me that the 6P3SE can go into a 240 as-is? Thank you.

Hi,

I have a Classe DR-10 with a couple of shorted power transistors.

Does anyone know of any suitable replacements? I have the service manual but it doesn't give the part numbers either. The transistors are ground down to get rid of the part number 😡.


Thanks in advance!

I recently acquired a Quad 306 power amp in excellent condition for free that was going to be thrown out, so of course, I had to take it! It powers on fine, and music plays through it, but the sound is quite muddy and distorted. Not massively, but enough to make it not fit for purpose as it is right now.

I opened it up to have a look, and I couldn't see any components that had obviously burnt out or anything. I did though notice that some modifications and some recapping had been done though. It looks like the 4 main (power supply?) capacitors have been replaced. The speaker inputs have been replaced, and looked like they were wired really badly to the PCB, so I desoldered the wires, and replaced them. This unfortunately did not help with the sound. I used 20AWG wire rated for 600V for this, is this wire fit for purpose?

Just a note, I'm not very experienced with electronics, I have some very rudimentary knowledge and basic soldering and multimeter skills, but I am keen and willing to learn.

On the underside of the board, there are 8 100nf capacitors, film capacitors I think. I have done a bit of research, and I'm pretty certain these are to decrease the input sensitivity, as the Quad 306's sensitivity is 375mV out of the factory. I have attached some photos of this.

Could anyone help me work out by how much exactly this is decreasing the input sensitivity? And could this mod be causing the sound issues? Would desoldering them be ok? I will attach a photo of the top side of the PCB, in case anyone can spot any other changes that might have been made that I've missed. Some of the solder joints on the underside are touching each other, could this cause anything?

Also, what should I do in a situation like this where an amp has a sound issue? I have seen some advice elsewhere that involves sending a sine wave through the amplifier, but I don't think I have the equipment to do this.

Thanks in advance for any help!

EDIT: I think I found some information on the mods that were done. It's a kit from here: https://www.dadaelectronics.eu/uplo...als/Quad-306-Upgrade-Revision-Manual-V1.4.pdf . The resistors at R6 have been changed from 120ohm to 64ohms. I don't think R13 has been changed, so the input sensitivity hasn't been changed I don't think. R9 reads as 27 whereas it should be 33, and it does match the colour for a 27ohm, so this might be incorrectly installed. R11 reads as 120ohm but should be 47ohms, so it looks like this either shouldn't be here as well, or was put in for some reason. R21 reads as 0.01 or 0ohms whereas it should be 22ohm. It looks like the right colour resistor though, as R20 is a 22ohm as well and it's the same colours.

Oh, and I've just realised, if I am correct that the person who did this was following this companies mod, there are only 8 caps fitted on the underside, as opposed to 10 in their manual.





Here are the photos: Quad 306 - Album on Imgur

p.s. The schematic is here Quad 306 Schematic and the manual is here https://www.dadaelectronics.eu/uploads/downloads/02_Quad-Service-Manuals/Quad-306-Service-Manual.pdf

Hi,

I've been registered for about a year so thought I should introduce myself.

I recently finished a Troels SBA 10 build, which was my first step into DIY (well, following instructions on someone else's build). It was a real challenge due to having no experience in woodwork or soldering. I now have lots of different tools I am reasonably competent in using. I've had "decent" speakers before from Rega but listening to the Troels was the first time I properly understood what "holographic", "lifelike" and "soundstage" really means when listening to music, they are remarkable. My source is digital and I power them with an old rega brio amp. The SBA10 were intended to be to be my last pair of speakers.

Anyway, I just purchased the linkwitz Lxmini with Ncore amps and the Nelson Pass AAC. These are controlled by an old meridian 501 pre amp (the one with the huge remote). I think the Lx may be better than the Troels in some ways. They are absolutely incredible. They took a while to set up (contrary to what I read about these being easy to place etc), but I absolutely love them.

I listen to mostly digital source from computer / tablet with an entry level "dacmagic" (I'm a bit skeptical about dacs).


I use a project rpm5 tt also with a goldring 1042 (I couldnt honestly say it sounds any better than my ipad).

I think my next step is to build my own speakers from scratch, which is a bit daunting (and improve my woodwork!).

I have pretty eclectic listening tastes and will listen to almost anything if it's good and has some passion.

Happy to help and contribute in any way I can.

Hi all!

As the subject line says, I am looking for 3-position rotary switch (for "Bass Turnover Frequency" Positions) for Pioneer SA-8500 II model. Also, a knob that goes on that shaft is missing as well. Original part numbers from service manual are:
- Bass Turnover Frequency, rotary switch, 3-positions: ASD-057
- Knob: AAB-116

If any of fiune people has one SA-8500 II for spare parts I would gladly pay for that switch and for that knob.

Feel free to contact me and also, if you know someone who might have spare parts, possibly point me to other direction.

Any help is highly appreciated!

Thanks a lot!!!

Stay safe & take care,

Krešo

This pair of TSL LSH75 electrostatic tweeters came from Abbey Road Studios when they were doing a cleanup a few years ago. One is brand new in its original box, the other is also new but the box is missing.

I believe they were made in Germany by Siemens, since they marketed a model LHS75K which, although similar, had a pressed metal frame at the rear. The gold stickers were also very similar, including the German text.

Now unobtainium, they sold in the UK for many years. The usual price was about 7/6 in 1956 and had raised to 12/6 by 1963 but could occasionally be found for far cheaper prices. Practical Wireless Nov 1963 p. 575 lists them at 2/6 each, plus 9d p & p and originally they came in a plain, square brown cardboard box. (First photo, not mine)

Recently I've seen just the instruction sheet alone for sale on Ebay UK at £20.00 including shipping.

I plan to fit these to a pair of older drivers, right in front of the dust caps, and run them with a valve amplifier. They cover the range from 8,000 cps to 20,000 cps. Yes, I did that on purpose, nobody would refer to kHz with something this old.

The dog harassment on my daily bike ride has now escalated to require the use of force. Guns can land one in too much trouble. Thinking about getting Dr Feelgood out of mothballs again, but it’s too unwieldy to use at speed. Back at university commuting through the ghetto every day it served me well. Water bottle full of ammonia perhaps? Or maybe tine for another 125 dB sonic disruptor (50 volts RMS into a piezo tweeter).

I bought a G36....right now i`m going over the machine. I havent had it powered up yet, but the seller (who inherited it from an uncle) did power it up - and everything seemed ok.
Sn is 62384, 2 track and 3,75/7,5 ips. Probably a mkIII

My question is:
There is no selector for mains voltage, only the fuse where the selector should be (according to the manual and photos on the net). See below...and swedish text for "högtalere").
Dont I have to move the mains wire to the 240V connections on the trafo inside - and shouldn't this be possible?

Caps seems fine and the ones I have meassured in circuit have fine values. For now I dont intent to change any caps or other components.
Motor spins freely activated by hand. For now I will leave motor as they are.

Br Torben

Hi. I'm a newbie DYI speaker builder and I'm currently designing a transmission line (TL) speaker using a 5.25 woofer and tweeter. My inspiration is the the PMC twenty5 series.

I understand that a TL speaker (when properly tuned) accentuates the bass which is why it can be an attractive concept in speaker design.

However, I have also been reading a lot into baffle loss where by bass energy is attenuated (up to 6db) via baffle diffraction.

My question is, when trying to model the speaker frequency response using available software tools, how do these to concepts compete with each other? At what point does the TL bass effect offset baffle loss?

Would be good to get your feedback on this...

cheers

I finally finished Project 97 Hi-Fi Tone-Control Preamplifier. I ordered the board and it arrived within a couple weeks.

I wanted to incorporate a USB/SDcard music player and a SPDIF OR TOSLINK input with a couple Aux inputs.

The PreAmp needs +/-15 vdc, the Music player needs 12 vdc and the SPDIF converter and input selector needs 5 vdc.

The USB Music player was a bit much for a LM7812, even with a heat-sink so I Built a regulator using a TIP3055, TIP31C and a 13v Zener diode.

For the SPDIF I used a LM7805 and powered it from the 12v regulator.

Nothing gets hot and the ripple voltage is about 1mv from the toroid power supply.

I'm using LM337 and LM317 for the +/-15v for the pre-amp.

It sounds very good, Quite (No Hum or hiss).

I did try the pre-amp kits from ebay and they did not sound as good.

I hope everyone's well,

So, I'm reading that Norman H. Crowhurst piece, "Making Use of Load Lines," in an attempt to learn something on my own.

He states that one establishes the two points for a load line by determining B+ voltage and dividing it by the value of the plate resistor to find the plate current. Clear enough.

When I look at the SSE schematic, I'm not seeing a resistor connected to the power tube plate. Which resistor, or, rather, what resistance value do I read off of the schematic in order to calculate a load line?

It's funny, but I always feel like I need to apologize for asking these very basic questions. But, the answer isn't obvious to me, and I know no other way to learn than to research, read, and then ask questions.

Thanks!
David

Has anyone compared their elekit tube amps to production stuff ? If so what were your findings? I know Herb Reichert said the TU8600 competes well with amps costing $20,000. I wonder if any has experience with comparisons to non-diy devices.

Can anyone point me to a good source of speaker driver design? I get the basic principles but do not understand what parts of the speaker affect the frequency response. For example what one designer's choices were made to make their 6-inch driver achieve a low frequency of 40hz while another 6 inches may go down to 50hz?

hello friends I have an M-Audio Tampa preamp with a signal input problem when raising the gain potentiometer the signal dies, I want to repair it but I cannot find the schematic circuit anywhere, can someone help me with this? please

Hello diy friends
I’m about to rebuild some crossovers in my Klipsch H1’s. I have a 3rd speaker that I’m going to use a the Guinea pig for this
My question is this, how do I do some before and after testing to see how well the new components will do on paper, as well as how well they sound to my ears. I have the laptop the test mic, and REW program installed on my laptop , I don’t really know how to use the program, lol
and I have an oscilloscope and Few different types meters for matching all my components with it as near as possible ESR on all the capacitors that I’ll be using.
I’m only changing the caps, nothing else , well maybe the wires inside the speaker cab
So could someone please direct me to a YouTube video or detailed instructions on how to accomplish all this so I can have some before and after measurements on this project? That way I can keep a log on what is working and what’s not working

Never used 12" Kappalites. I was building enclosures when I switched game plans. $180 SHIPPED **** SOLD ****

&#160

A woman awoke during the night to find that her husband was not in bed.
She put on her robe and went downstairs. He was sitting at the kitchen table with a cup of coffee in front of him. He appeared to be deep in thought, just staring at the wall. She saw him wipe a tear from his eye and take a sip of his coffee.

"What's the matter dear? Why are you down here at this time of night?" she asked.

"Do you remember 20 years ago when we were dating and you were only 16?" he asked.

"Yes I do." she replied.

"Do you remember when your father caught us in the back seat of my car?"

"Yes I remember."

"Do you remember your father when he shoved that shotgun in my face and said, 'Either you marry my daughter or spend twenty years in jail'?"

"Yes I do", she replied. He wiped another tear from his cheek and said, " You know I would have gotten out today." 🙁

Amp stays powered up after removing remote wire.

IC1 voltage says the same with or without remote connected


1: 0.94v
2: 2.99v
3: 0.09v
4: 0.03v
5: 1.52v
6: 3.39v
7: 0.03v
8: 13.25v
9: 5.63v
10: 5.60v
11: 13.25v
12: 13.78v
13: 4.98v
14: 4.98v
15: 4.98v
16: 4.98v

I think the replacement for the 2SA1085 is a KSA992 which is available, but I don't know of an available one for the 2SC25457. (MC Preamp)

Any thoughts ?

Thanks.

Audio Precision APx525 as follows:

• Date of manufacture: 2014/11/24
• Date of last calibration: 2017/04/28
• Included options: DIO (Digital I/O)
• Included accessories: KeyBox, original shipping box, manual, power cord, USB cable.
• Condition: Like new. Passes all self tests.
• Price: $10900

I will accept payment by bank transfer or credit card at no fee. If you insist on paying via PayPal I will have to add a 4% fee, which will be invoiced separately.

You can purchase it directly on my website: Audio Precision APx525 w/DIO - For Sale by Original Owner – Neurochrome That's also where you'll find the shipping rates.

The pictures show the exact analyzer for sale. I've blanked out the last digits of the serial number where appropriate.

This is the exact analyzer used for all the AP measurements you seen on my website. I have owned it since I bought it brand new from AP in November of 2014 and it's seen regular use. I baby my equipment, so the analyzer is in like-new condition. It passes all self tests as you can see in the test reports attached here.

With the KeyBox installed, this analyzer will run the APx500 software up to version 4.6. You can download the software for free from AP.

I'm only selling as I have an upgrade coming.

The APx525 is the second-best audio analyzer in the world. It's bested only by the APx555 which is about three times as expensive.
These analyzers fetch a pretty penny on the used market and I have mine competitively priced.

Naturally I only have one available. 🙂

Thanks,

Tom

I read somewhere that a low mass ESL diaphragm very effectively damped by a higher mass of air surrounding it and coupling to it.

I’ve been pondering the damping effect of the surrounding air mass, and how to quantify it. The problem is that I lack physics smarts and I really suck at math.

If the damping volume is merely equivalent to the diaphragm’s excursion x area, then the answer is air density x that volume.

But my gut feel is that the actual damping volume must be greater than merely the equivalent volume of the diaphragm’s excursion, because that volume of air would not be pushing into a surrounding space that’s empty and devoid of air, but into a surrounding sea of air. And if so; the coupling would not cease sharply at the diaphragm’s excursion limit but would progressively decrease with increasing distance from the diaphragm.

If the above is correct; I’m thinking that a quantifying equation must factor in the compressibility of the air at room temp & sea level pressure.
And I figure the air eventually gets out of the way of the progressing displacement and de-couples from the diaphragm, but I have no clue how to quantify the effective damping volume/mass of that air, or even determine whether the damping volume equates to only the equivalent diaphragm excursion or extends beyond it.

Would anyone care to share their thoughts on this?

Hello All

I have been repairing Klipsch subwoofer amps for about 15 years as a hobby. I have decided to start blogging my repairs and eventually do videos of each one. This thread is intended to be a blog and a resource for information. I will try to answer repair questions as best I can. Comments and tips are also welcome, If you do not have the experience or the tools, PLEASE do not attempt any of these repairs. You will only end up damaging the board and it will end up costing more for a tech to repair the damage. If you do not have a high quality vacuum desoldering station (Hakko or Weller) and a current limited mains supply, you should not be working on these amps. These subwoofers do not have any user serviceable parts inside. If you open up the sub or attempt any repair you see in this thread, you are doing so at your own risk!!!

Finished my Grilles...What a mission..

Can't post on it or see/click on the'picture's little gray dots plus can only close the DIY audio tab as it's locked up and have to wait a bit and reload by clicking an email link. Tried several times, so no fluke; otherwise can go about my business if I avoid this thread.

Working on an Audiopipe APSM-1500. Goes immediately in to protect when powering up. No shorted outputs or mosfets in the power supply. No drive to the gates of the power supply mosfets.Anyone have a schematic of the protect circuit?

Sold
For sale, DIYAudio Full F6 kit with all components including the Linear Systems Matched J-Fets. Currently out of stock in the DIYA Store.
I bought these with the intent to build an F6 after my ACAs, but now have a burning desire to build a SissySit V.3 and need to fund that build.

There in no Power Supply with this sale, only the Amp PCBs, Transformers, Active and Passive Components (FETS and J-FETS). See pictures for what is included.

Item is located in the UK, but will ship anywhere at buyer's expense.
Selling for $199/£150/E175 + Shipping.

Any questions, please ask.

Jon

and its in lovely condition


think i might keep this one for myself 😉

The usual scheme to use cheap power Xfmrs for an OT generally runs into the limitation of primary impedance attainable and AC voltage swing at LF.

One can use two P-P Xfmrs in the Norman Crowhurst Twin Coupled mode to double the primary Z and V, but then one is stuck with 50% CFB. And no further Z increase is obtainable.

Here is a method, using the simplest single winding primary Xfmrs, with no need to use CFB, although that can still be done if wanted.

More Xfmrs can be connected in series in each phase side to get even higher primary Z. They need to all be the same turns ratio in order for secondary DC current to neutralize the primary DC currents accurately. Secondary DC is kept out of the speaker, and the AC signal is kept out of the LV power supply.

One converts the primary DC current to the higher secondary current using the turns ratio, then use a LV power supply to neutralize that current. Secondary current will be the LV divided by the total secondary copper resistance it flows thru.

Power consumption is only a few Watts. (a current source type compensation would require high Watts)

Warning!!
Increasing the voltage rating this way may lead to exceeding the V ratings of the individual Xfmrs. (primary to secondary and primary to core AC and DC ratings)
NOT recommended under any circumstances for HV transmitting tubes.

Connecting secondaries in parallel (per phase side) is NOT recommended, since a small difference in copper resistance would lead to unequal compensation currents in the paralleled secondary Xfmrs. Unequal copper resistance between two similar Xfmrs could be compensated by DC biasing the tubes slightly differently.

Keep in mind that normal P-P operation reaches 2X the B+ under ideal conditions. Resonances (Xfmr or speaker ) and loose connections can lead to 10X easily. Then there are corona and insulation leakage issues at HV.

Hello,
I'm not sure where to post this but hopefully should be simple to answer. I'm going to use this CCS on tube cathodes. It will be referenced to a negative supply since there isn't enough voltage from cathodes to ground. It also requires a positive supply to bias the zener and this will come from B+ since it's the only available. I have a couple of questions about this. First, do all these supplies need to be super clean? It would be handy to get them from early stage of filtering and there will be a few volts of ripple. I'm thinking that it should work but is it optimal? Especially for the B+ there is a very convenient point to tap at the heaters DC elevation, the usual voltage divider bypassed with a cap. Would this work? The second question is if there is any problem from that all these supplies are used in different stages of the amp and none on the tubes where the CCS is attached. All of them are referenced at the same ground though.

I listen to music as a background while I work on my computer in a small 12x10 guest room. So the volume is fairly low level. I either listen to CDs or sometimes music from YouTube. I never make recordings or create mixes.

I'm trying to decide which purchase would create the better experience:
2 Presonus e5xt sitting on the ends of my large (it's a former door) computer desk (about 3 feet from my ears) producing stereo; OR
1 Presonus e8xt sitting across the room (about 8-9 feet from my ears) producing mono (really, summed stereo).
The cost for each is comparable.

Opinions most welcome.

bought the above from ebay- its making my capstan etc pink - i cleaned a bit with alchohol and q-tip and that turned pink- is this normal?









RoXdon 1/4" Reel to Reel Red Leader Tape 305 meters | eBay

So I exhausted the web searches with no solutions

R53 was extra crispy so I replaced it leaving it elevated
C71 got a little diss colored but test ok with ESR meter
Board is grounded
No DC load to speaker
Tube test good even swapped it with no luck
Solder joints all look good

With everything on ten I can here faint guitar through speaker, headphones and extension speaker. If I make reverb rattle that’s louder.
Faint output through CD

Any help greatly appreciated thx

Hello,
just got a AR VS 110 off A-gon, went to check the bias, two ports gave me zero readings. Swapping power tubes did not help.

Would appreciate your feedback gentlemen!

In applications not needing the sensitivity of a compression driver K-tube combo, nor worry of either its projection, or embarrassing phallic overtones 😱, a flat face mini-Karlson tweeter could be considered for: multi-way, helper, and "FAST" work.

I would pick a "hot" small cone FR (or one tweeter) perefably with rising on axis response (as horizontal polars will be spread by the vari-width aperture}
With some drivers with a powerful rise, I would consider a narrow aperture that "shades" more of the cone than Karlson's work.

Also for the wedge front chamber, I suggest 20 degree angle, and not much height above the driver as to minimize front chamber resonances.

XRK971 has made (and measured) a number of small diameter Karlson variants so may give more ideas.

Here is an interesting new transformer vendor based in Belgium. Their product line looks quite interesting, specializing in tube output transformers and the like - so I thought I would pass along the tip.

Here's their site: MONOLITH MAGNETICS

Please note I have no affiliation, and have not tried their magnetics either. Always good to have another choice IMHO..

hello,

i'm looking for a friend of mine, the schema of the MC275 CE, or the differences between the standard and CE versions.

thanx,

didier (france)

I need to order some more 1N4007s. I usually stick with OnSemi or Vishay, but looking at the other options (some cheaper) on Mouser, I wondered: What, if any, difference is there between the big name brands and the others? Or to phrase it another way: Do you just buy the cheapest available 1N4001-1N4007 rectifiers available from a trusted source, a la Mouser, Digikey, Arrow, etc?

While I may never design my own circuits. I figured learning how to lay out a circuit board would be very useful for taking advantage of all the shared projects on this forum as well as reducing the cost of my builds. I've got a few tube preamp builds in mind. So I wanted to try an all in one regulated B+ and heater supply board. The heater supply is a copy of Pete Millet's low voltage regulator minus the CMC. And the B+ regulator is copied from the Antique Wireless World circuit based on the LR8N chip. Boards are available, of the individual circuits, from their respective designers. That being said I have no intention of sharing design files or boards. If, however, somebody is feeling generous with their time. I'd appreciate any feedback on my layout.

Enough talk. Here it is.

I call it the "Little Miracle" because of what it can do but still be 100mm square for economic purposes...

It uses one 6F12P and a pair of 6P43P/EL86/EL84/6BQ5/ whatever tube shares the pinout. Add power and OPT. 300V for B+ 600V for first stage (or 300V, with higher Dtot). I use isolation transformers with a Delon/quadrupler.

You can connect as triode, pentode, or UL by way of jumpers. Provisions are made for zener shunt screens.

You can use 2 400V 100uF or one 600V 47uF cap for the filters, that's why they overlap.. TL783/LM317 for CCS cathode biasing.

Rset is a test point, or omit the pot and install a fixed resistor.

PCB values are based on EL86/6P43P.

I'll sell a pair of these boards for 20$ shipped anywhere Canada Post will send mail. Kits available.

Good morning everybody!!

I've purchased a 2nd hand (damaged) Marantz PM-84 MkII for a few bucks.

(Hope one day I will own a PM-94 🙂)

I've found the problem, as per picture under this line



My problem is I do not know values for adjusting new potentiometers... As you can see one of them has serious damages (R726)

I've found PM-84 SM (not MKII) but it is quiete different and less sophisticated 😡

So, if anyone can provide me the right values (and the how-to) or else can provide me the whole SM for PM-84 Mk II I will acklowledge so much!!

About me : I live on Majorca-Island and I am building amplifiers and active speakers for a number of friends and clients although I am retired.
When building the above there is the question of what power-supply to use for the gear I am building.
Since the speakers generally are stationary and 3-way units with 12“ bass drivers they already weigh from about 30 Kgs and upwards. The amps weigh less but are stationary as well . So , in both cases , the absolute weight is secondary .
Concerning the amplifiers those can all be executed as BTL which allows for surprising output with one only rail without large output capacitors . Depending on the rail voltage one can reach 100 w with 8 ohm speakers and 200 if 4 ohms are used , with no problems at all .
Any amplifier needs a strong and clean power-supply to be able to output a good bass which implies a relatively high cost for rails between 24 and 50 volts and currents up to between 10 and 20 amps even if it´s only for impulses

Due to all of the above I have successfully built several units with a different concept for the power-supply :
I have used 2 , 3 , and 4 12volt 7Ah AGM-batteries in series ( weight is aprox. 2 kg per battery ) with two parallel capacitors , one of 4700 uF and one 4,7 uF . The internal resistance of one battery is only about 23 mOhms so less than 0.1 ohm for 4 of them and the whole buffered with the two parallel capacitors.
The charging power-supply can be any switched power-supply with an output of 50 watts or more followed by a buck or boost module adjusted to 13.8 volts per battery so 27,6 for two , 41,1 for three.
Disadvange is the weight , advantages are that it is practically noise-free , and extremely high current capacity , cost of about 60 bucks for the whole thing . I obtain the current capacity of a very large transformer-based power-supply ( Which is not a light weight either ) and the stability of an SMPS , and even considerable immunity from power failures .
I love to do unconventional things and I would love a discussion on the subject.

Hello, i received this amp. It starts clipping very early. It seems, everything ok.
Tested at 2.4 Ohms, input current 130Amps, 12,3V, the amp starts allready cliiping, and railvoltage drops from 88V to 70 Volt.

Railvoltage looks also very low to me. Railcaps 160V, Railvoltage +88V, -88V.
It looks, that one transfomers is damaged, but i cant desolder, because plenty glue arround..

is there a reasonable portable cd player that can be used in home stereo setup? It would have to have an AC adapter, optical/coaxial output would be a plus. Likely there would be no remote but shuffle button on the unit face would be nice but not required.

I am open to an older or newer portable units...

Newbie designing a 10W class AB Hybrid

(Yes, I know it has tubes but given the topology I hope this fits best here.)

Hello kind people, I'm just looking for a bit of a sanity check on this design. I was shooting for 10W output in class AB, using ECC84/6N14P tubes as a front end since I have a few hanging around. It seems to simulate well, but I'm a complete novice so please let me know if you spot any mistakes, or just throw an opinion in. The main thing I'm looking for is squishing the overshoot on the falling edge of the square wave, throwing capacitance at it doesn't work.

One other thing, are there any specific simulations I should be running? I've run a few and attached them, but are there anything I should be doing specifically? e.g. THD at Y frequency and Z amplitude etc.

Many thanks!

So I've been away a few months, and come back to find that in the interim a lottery has been run for VFET amp kits. To say I was a little miffed would be something of an understatement. So, I decided that rather than getting mad, I'd get even. Say hello to my little friend. Should play those Eikonas that Colin is shipping from the UK with aplomb.

Yes, the Victor JM-S7. 110W per channel of VFETish goodness, straight out of 1975. It cost me an arm, a leg and a testicle but it's all worth it I tell you.

I am selling 12,5" Audiogroove II Titanum tonearm.
Used shortly, like new condition, full set excluding carton box.
New 2200EUR

my price 1700EUR total, shipping included. Price is fixed and wont be lower.

I know the specifics of this are a lot more complex to calculate properly than I'm describing here, not trying to model a speaker design off the answer - just trying to take my limited understanding one small step forward.

If I have a 3 way passive crossover that's designed to drive 8 ohm speakers and I have an 8 ohm speaker wired to each of the crossover outlets (Low, Mid, High) - under 'normal' use - what load is the amp going to see?

I took a guess at approximately 8 ohms but my best explanation for that answer was pretty garbled!

Thanks 🙂

First time build. So far so good. Just have one tower left to sand and paint.

The paint is just polished Krylon from lowes.

Powering everything with a Pioneer SC-27 so it should be about 160 watts to each tower and 180 to the center. I would like to hear them with a separate power amp at some point to see if theres a difference but so far the few times I listened to them before paint and the receiver didnt have any problem running them into loud levels.

I need to make some kinda stand for the center channel. I have some MDF left over I might try and make something with.

Otherwise the room is going to be hit or miss. I have it setup so it's wider than deep. 22x17ft. I'm going to test it the other way and see how the towers sound. It's an extra room with a lot of brick walls and glass with aluminum ceiling. I just threw a bunch of curtains around and it toned down the reflections.

I think they look OK. The Faux Ali frames do show through a little.. Over all I am pleased...


Sideways pictures , I'm sorry.. They open the right way up at my end...

I have an old dinosaur of an amplifier here that I use for my party system. I swapped the woofers over for a couple of 4R drivers and it's been getting quite warm lately.
It's an Inkel ARM1200
Dual mono
63V 10.000uF smoothing caps and SanKen 2SC2774//SSA1170
Been really reliable but this is the first time I've had it driving 4R loads.
It's got output metres on the front rated to 200W into an 8R load but I have no idea what it might be rated into a lower impedance speaker.
Driving big old fashioned Alpine 12"car subs to handle some party bass that are supposed to be rated 300 watts.
Is expecting 300 watts realistic?

Hi guys,

I'm having issues with a buzzing noise on my self made pre amp.
I manufactured it (together with a power amp, see pictures) during my apprenticeship 22 years ago. I believe the noise was present since ever, that's why it did not use for a longer time.


Unfortunately I did not have an oscilloscope in place to track down the noise.
However, I can state the following:

• The buzzing noise is constantly present and not depending on any switching to different inputs or connecting/unconnecting inputs.
• As well it appears when the volume is down.
• I used the spectroid app on the handy to record the noise in front of the speaker. There are obvious peaks at 50Hz, 100Hz, 200Hz and harmonics. See attachment for details of the spectragram.
• The root cause must be somewhere in or before the power supply (see schematics attached). Btw. my supply is +/12V instead of 15V, using LM7812/7912 from Motorola (output noise voltage Vn = 10uV/Vo).
  As well the filter before the voltage regulator is modified with an RC-circuit (10R and 4700uF Elko instead of 2200uF))
• When disconnecting the internal power supply +12/-12V and using an external device, the noise dissapears.
• Exchanging all capacitors on the power supply did not solve the problem
• Exchanging the rectifier did not solve the problem
• Exchanging to different voltage regulators LM7812/7912 from On Semi did not help. It even amplified to problem (higher Vn = 40uV/Vo might be responsible).
• I checked the ground routing with an ohm-meter, every assembly seems well connected to ground and the housing.
• Exchanging the transformer does not solve the problem.

If any of you experienced guys has a tip for me, very welcome!
Thanks in advance, Michael

I've been doing some 2-way speaker designs over the past couple of days. I had some questions about speaker nominal impedance and compatibility with my AV receiver.

In my first design with these speakers, I wired 2-ohm woofers in parallel and wired those in parallel with a 4-ohm tweeter. Here are the resulting Frequency Response, Crossover Design, and Impedance graphs:




I currently own an ONKYO TX-NR609 receiver which is rated down to 6 ohms and can go lower, but the protection circuit may be activated. This impedance graph gets down to 1.8 ohms at around 600hz which to me seems ridiculous, and it would definitely not work for my receiver.

I really wanted to use these drivers, so I decided to just play around to see what happened to the impedance graph in different wiring configurations. I wired the woofers in series (16 ohm) in parallel with the tweeter. Here are the resulting Frequency Response, Crossover Design, and Impedance graphs:





Heres the real questions I have:

In the first graph what would the nominal impedance be considered? 4 ohms? I'm just surprised at how low it goes.

In the second graph, what would the nominal impedance be considered there? I've tried searching to see what people say online, and I've watched a couple of youtube videos. One YouTuber says the nominal impedance should be the impedance of the woofers which should be 16 ohms. It looks to me more like 6 ohms? Is it the crossover that is lowering impedance that much?

Is there anything that makes a certain impedance graph better than others?

When it comes to powering a speaker with a lower impedance than an amp is rated for, what happens? I've looked all over the internet and everything I see is that it will damage the amp. Would this not allow the amp to overpower the speakers more easily if the rated power of the speakers was less than the amp was capable of? To me, it seems that the speakers would be at a higher risk of being damaged.

Hi All,

I recently got a non-working NAD 326bee. It makes a loud buzzing sound through the headphones, regardless of volume. No music can be heard, only buzzing.

I went ahead and rebuilt most of the PSU board (all the capacitors, the two transistors, an optocoupler, and a DB105 IC). Theres a TINYSWITCH-III TNY274PN, another IC called DB104, and then several rectifier diodes that i didn't touch, only because i couldn't find the equivalents at Digikey. Mouser seems to have all but the tinyswitch, but i want to stop any more shotgun replacement and actually learn how to diagnose the thing.

When i power it on, i get buzzing (and blue power light) and then 2 seconds later the buzzing cuts off and i guess it goes into protection as i hear the relay click, and the blue light turns orange.

The DC volt readings at both speaker terminals are 0.005V right before the relay clicks.

I would like to go through the schematic and test for voltages here and there, but there are no voltages listed so i don't know what to do next, and need help.

Thanks for listening, and i look forward for guidance on where to start.

So...I brought my Onkyo SKW-593 and HT-R494 from US to EU. It appears to be hooked up fine, but the led on the sub does not light (and obviously there is no sound). Of course you are now thinking that I burned it by plugging into 220v outlet, but I'm using this voltage converter (https://www.amazon.com/gp/product/B07D957SZY/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1).

The receiver works fine.

Any ideas?

I am refurbishing a NAD 3140 and found an NTE 5645 Triac inserted in the AC to the power switch- not an original part!


(photo attached)


I assume it was an attempt to reduce turn on thump (which the owner says the amp still does)- any insights as to what it is intended to do is appreciated.


I am recapping the unit top to bottom.

I am hoping someone has a B&K CS-117 laying around so I can find out what type and how many fuses this unit uses.

The manual states 1/2 amp fast blow but has different marking’s on the fuse holder mechanism.

So if someone has one could you please let me if it requires two (which the fuse holder holds) and if they are 120V 1/2 amp fast blow.

I have attached a picture of the only values I see on the holder which does not look correct in way, shape or form.

Thanks, James

Lets assume a crossover frequency of 1000Hz and 2 drivers each having an 8 ohm impedance. We feed that into an online calculator and it spits out the values for a 2nd order L-R of 1.3mH and 20Uf. For the LPF; its a series inductor and a parallel capacitor. The HPF, just reverse the components. I understand how the impedance increases with rising frequency and how the capacitor bleeds off more signal. Different values different cut-off. Cool! we can build that.

What happens if we change just one of those values? Coils are expensive but its relatively cheap to add or subtract capacitance. What effect does changing only one component have? Change the frequency? Change the linearity? Multi phase shifts. Space time distortion? I cant find anything on the web.

Good morning everyone. I have modified the crossover of my BW DM602 based on what was published by Rutcho (mine are S1).
I have noticed an improvement for my ears since I noticed them with fatigued treble, I have noticed improvement in the scene and more defined bass.
All this with my ears since I do not have measuring instruments.
The original crossover is low pass first order and high pass third order. With tweeter in the same polarity as the woofer.
With the modification, the second order low pass remains, the high pass continues with the third order and the polarity of the tweeter reversed.
I have read the different degrees of phase shift that happens when we use first, second, third order crossovers, but I have not found what the phases look like when mixing low pass second order and high pass third order.
Although I find it nice how they sound now, I don't know if the modification of the phases hides or accentuates any range of frequencies.
Thanks a lo
This is the modification. Added a 1.5 ohm resistor, replaced 4.7uF in high pass by 3.3uF and added 4.7uf and a 2 ohms resistor in low pass. Tweeter inversion.

Hi,

I bought this 6L6 tube amp last year and decided to tweak
it a little. Has anyone tried tube-rolling with this amp?
And how does one set the bias? I couldn't find a way
to do it.

Many thanks,

Mike

Hi, I will be using a sundown nsv3 18 sub on 8kw of power.
This is going in a trunk, so space is limited.
I was planning on doing a normal reflex enclosure, but it will get tremendous cabin gain, so I would also like some added efficiency on the higher side of bass.

What is the difference between a quasi 6th order and dual reflex? Does one have better transients or efficiency?

I planned roughly that a 250l reflex tuned to 25hz with 700-800cm2 of port area, would fit in the trunk.

I might be able to get a little more air space. But would it be possible or reasonable to make a more complicated design with this space?

I'd like to share my latest blog post. The Yamaha JA6681B measures well. It would be suitable in a high sensitivity 2-way. The diaphragm uses a unique surround comprising 15 little copper beryllium arms that flex. This results in a very low 300Hz FS. Impressive!

Yamaha JA6681B Compression Driver – Joseph Crowe

Hello!
If I want to add gas tube to the existing power supply for 300v B+ regulation. Between 2x0A2 and 2x0D3, which one would be your choice for Aikido 6SN7?

Thanks!

In March a friend asked me if I would like to design something simple
with the IRS2092. First I was not enthusiastic, because I had doubts that
it would work to achieve something better than the IRAUD7 and its clones.
Better means: Improved speaker control (==> post filter feedback), less noise and at least not worse distortion.
Nevertheless I had look into the topic.
My first attempts were fitting more or less to my expectations.
Good control of the filter and speaker, blameless step response, but harmonics in the -70db category all over the place. Ugh..
Also the gap between simulation and reality was to big for my taste.
Operating frequency and distortion figures did not fit sufficiently.
I digged deeper into the non documented weaknesses of the IRS2092.
Key points:
Transfer function of the OTA
Noise of the OTA
Jittery / ambitious flipping of the comparator
Internal delay times

After all this I updated my simulation model of the IRS2092 and soon came to
a changed structure, which behaves fine in simulation and reality.
Can't tell an official name for the structure.
With a good portion of phantasy we could call it a post filter feedback sigma delta modulator.
Above 60kHz F1(s) and F2(s) together are acting like an integrator for the 1Bit data stream coming from the half bridge...

In the mean time the results by far surpass the IRAUD7, but the complexity is very similar.
Step response is blameless with rise times below 5us, output noise is below 100uVrms, very low THD and nice dual tone behavior.
It is promising enough that I intend to go for a proper PCB.
Attached a scheme of the control structure and some measurements at 10W into 4R.

Considering a new build. I happen to have a 1.5 cu ft cabinet in my shop not being used so I was thinking either a 2way or 3 way. I have a sub so I don’t need subterranean bass.
7 or 8 inch woofer and 1 inch dome
Or
7 or 8 inch woofer, 1 inch dome and Fountek Neo 3 (Hate to use the term super tweeter but this is kind of like Harbeths 3 way with 2 tweeters.)

In a separate thread I was suggested these 2 tweeters
D2604 or DX25BCG60

Woofers under consideration: SS 18W/8531G, Seas W22NY, Seas U22REX, Dayton RS225P-8.

The W22NY is expensive so unless there is a compelling reason to use it. My focus is on clean mids that have a relaxed natural sound. I don’t want ultra detail at the expense of musicality. Your thoughts are welcomed and appreciated. Thank you.

The idea would be to build speakers with a sub box separated from the mid-high range to facilitate transport and positioning. Here's what I came up with drawing inspiration from the "the loudspeaker" project :

- 40-200hz: l18p200n box reflex 200liter (i have)
- 200-1200hz: 10NMBA520 sealed box 18lt (to buy)
- 1200-10000hz: rcf n980+h6040 (i have)
- 10000-20000hz: Beyma CP21/F (to buy)

bi-amped with powersoft amplifier, basic crox and correct with dcx2496

can it work? Can you help me find something wrong before I waste money and time?

Selling my DAC 1321. Beautiful shape with all the packaging, etc.

$250 USD plus shipping

These sound GREAT !

Hello,

After years of neglect and abandonment, I have started refurbishing my X2 sl1210 MK2 that used to belong to a mobile dj. I need two phono interfaces and wish to have them available side to side to testy/ compare incremental upgrades. This is my redintrodution to analog after years solely residing on the digital domain.

I used to volunteer in a ln alternative College radio station in the 90s. We had this large mixing board with remote star stop, super nice faders, two mics, 3 sl1200 mk2, 3 CD players and 4 8 track style cartridge with a cassette deck to record your shows. It was awesome, both in functionality and sound quality. I am not interested in dj style mixing but to reproduce ( sans the mic) some of the feeling and functionality of the system for personal use.

My actual system is composed of two aiyima amps, one full range and one sub, connected to a topping dac and pc and Nas box as interface and music repository. As such, there is only a single line input used by the dac.

In order to connect the sl1210s, first I tried with an old Kenwood receiver taken out of storage and using the monitor out to drive the amplifiers. Only one phono interface

My second try has been with a Behringer DXJ900 USB. I can connect both amps (sub and main) and control level independently, the turntable pre is decent and i can have both turntable connected. But it's rather noisy, the master fader is useless over 4 as it hisses too much for my liking.

Other option would be to buy a couple phone interfaces, such as the art dj pre Ii, see ASR review, get some better power supplies and use some kind of passive switch or an avr with preouts, but i believe a mixer may be more flexible.

i am looking for a mixer to be used in hifi, preferebly purely analog, with two good phono preamps, three or more channel with clean sound. On a perfect word i would like to have the tables, CD players and dac conected so i could play all my formats.

Sadly, i cannot afford a broadcast grade 24 channel stereo with remote start stop 🙁

Any of you have set a similar system for personal use or any comment/ suggestions of what may be the best way to go, or a brand of a decent phono analog mixer.

Tks in advance, Francis.

FS: Nelson Pass 2-way Jfet XO kit (PCB + Jfets + Bias resistors).
Have 2 units available, bought extras 'cos I usually make too many mistakes.
My 2-board 3-way XO build went together without a hitch, so am offering 2 more unassembled spares, singly or together. Random collection of caps & Rs etc will be included.
$75AU + postage each, or local pickup Melbourne (when Covid lockdown ends).
Cash or bank deposit.

I need schematic CXA 1081m Sony.

Hi,

I've a prototype circuit interfacing a DIR9001 (spdif) into 2x PCM1794A's which go into 12x NE5534's and output as balanced audio L & R.

So far I've verified by scope that I2S is coming out the DIR9001, all lines are good. Soldering has been verified under microscope, no problem there. Despite this I'm unable to get output from either PCM1794A. I've verified both DIR9001 & PCM1794A are in 24 bit I2S mode. The mute pin on both is grounded. 3.3v & 5v lines are perfect. I can't see any output on scope going to the first op-amps.

Anything I'm missing?

Good day Group! I am trying to upgrade my MF A-370 clone.
In this instance, I am looking at the VAS and driver stages (see attached schematic diagram), considering higher power BJTs. Not sure this would give significant improvements, would appreciate some help from the Group experts.

In the VAS stage (the BJTs are in common-base configuration) I am considering to replace the MPSA43/93 with KSC3503/KSA1381, capable of higher power. Is this a good idea? Any other device could be better?

The gate driver stage (emitter-follower configuration) uses BC414c/BC416c.
I understand the power mosfet gates would be better driven by higher power devices due to their capacitive nature (I am using 2sk135/2SJ50, 900 and 600 pF). Also here I am considering suitable higher power BJTs (TO126 or TO220). I searched the forum but did not find any clear suggestion. Would therefore appreciate some help.

Thanks and Regards, Giovanni

I'm confused

If I'm after a 32V rail voltage, what transformer secondary voltage rating do I need? I have read where there's a voltage drop from the transformer onward so can someone please explain how Nelson would get 32V rails from 24V secondary's as per the below quote please?

QUOTE from paper on the F5 & F5T by Nelson Pass..

Increasing the power supply voltage is the obvious way to get more power out of an F5. You can simply raise the supply rails to +/-32 Volts and get 50 watts into 8 ohms right away without other modification. 24 V AC secondaries on the power transformer will do it. Don't forget to use higher voltage power supply capacitors.