I'm adding a shunting relay to mute the output of a tube preamp. The issue is mostly at power down, I get a big bump on the output. I've read all the threads on this, but my question is a little different.

My chassis is already extremely tight, so I have room for a mini relay and maybe a resistor and diode that's it. I don't wish to create any elaborate circuits. I'm choosing only to address the turn-off bump at this time because it's most egregious. My power amp has a delay turn/on function when using a trigger, so any noise coming from the preamp associated with the slow B+ climb are solved enough for now. Turning off the amp via the trigger does not happen fast enough to avoid the turn-off bump from the preamp however.

I have a small 12VDC power supply already in the chassis for a 12V trigger, and LEDs and such, so I can use this to control the relay. Because the power-off bump happens so quickly after I turn off the amp (or physically unplug it), I need the relay to de-energize very quickly, before the B+ collapses, in order to shunt via the NC contact.

I'm thinking to use this relay. Like most relays, it energizes at 80% of rated V, and de-energizes at 10% which is way down at 1.2V.

QUESTION
Can I make the relay de-energize more quickly and at a higher V, like lets say 8V, by using a zener somehow? Will the attached sketch work? I may totally be misunderstanding how zeners actually work, so pardon if this is a silly question. I'm a little unclear if the zener conducts the full voltage from cathode to anode when reverse biased, or if it drops the full voltage equivalent to the breakdown voltage.

Simple question - what high voltage connectors are you using, or thinking of using, or know of?

Basically voltages above 250v and typically up to 450v for tube equipment.

Something available and not too expensive would be good.

Hi,

I'm in Bulgaria on a vacation and was wondering if anybody knows some shops around here that sell tubes and/or tube equipment.
Russian tubes should be plenty around here I guess..

Hi Forum,

I have a Sony CFD-ZW755 RADIO/CD/TAPE player I have had for 10 plus years and the cd player recently died. From my research it sounds like the optical pick-up on the cd mechanism has failed. I found the service manual and it says the cd mechanism I have is a KSM-213RDM because my serial number is greater than 0560201. Before that point the unit used a KSM-213CDM. My problem is I can't find a KSM-213RDM available but I have found the KSM-213CDM.

Does anyone know if these two cd mechanisms are interchangeable or is there some other cd mechanism that will work for the KSM-213RDM?

The reason I want to try to repair my current machine is because I have not been able to find anything new out there that has the size and power of my current boombox with radio/cd/tape features.

I'm kinda stuck and don't know what else to do so any feedback would be super appreciated.
Thanks all.
Best,
-Tim

Hi,

Does this make sense ? Harbeth 40.2 flagship speaker...


Diffraction horn like ? Or a way to deal with the cabinet corners ? Aesthetic ?

SOLD SOLD SOLD FS Like new pair JBL 2453H-SL compression drivers

Hello, I'm parting out systems to make room for new projects.

I got these from Speaker Exchange new back in June 2020. Cosmetically and functionally 10/10. $600 shipped in original boxes within CONUS. I'll ship internationally at your cost. Thanks for looking!

I also have a pair of 2384 horns that we can talk about but shipping on those is pretty expensive. PM me to discuss a fair price for the horns.

Selling used FO v1.2 modules. They are set for 45V, so Hypex SMPS1200A180 would be the recommended power supply.

More information in this thread: First One - mosfet amplifier module

Asking price: 130 EUR + shipping from Latvia.

Selling here new unpacked amplifier case with heatsinks. I am using another 3 for my active 3-way system with a pair of First One amplifiers and Hypex SMPS in each case (see picture attached). I wanted to make a 4-way system, but decided to stay with a 3-way.
The case is very solid and high quality. Buttons, power cord socket, screws and rubber feet included.

External dimensions: 320x311x120mm
Internal dimensions:300x220x112mm

Bought few months ago here: Leistungsverstarker Gehause Aluminum DIY Metal Case for Power Amplifier Chassis | eBay

My asking price: 145 EUR + shipping from Latvia

I purchased this XMOX xCORE-USB development kit a bit over 6 years ago for work on a digital music synthesizer project. I also got the Audio Slice Kit.

It all got packed up to move house before the project ever got started. I moved twice in 6 months totaling 1200 miles, both on short notice. Stuff got lost. I'm still digging through boxes that haven't been opened since I left Florida on 3 weeks notice in 2014.

I just opened the box this stuff was in yesterday, so it has seen no use, ever. Everything is still in the box including the DigiKey receipt for $253. All is unused except the 12 volt 2.5 amp power supply is missing. I don't know where it went. Asking $100.

Box contents:

XP-SKC-UC16 core board
XA-SK-USB-AB USB interface board
XA-XTAG2 JTAG programmer board
XA-SK-MIXED-SIGNAL I/O board with joystick
USB extension cable
PSU (12V 2.5A) is MISSING
XA-SK-AUDIO audio and MIDI interface board

For Sale:

Power Caps
4x 15,000 uF Adcom $40 obo These have been boxed since at least 2006 (not sure exactly) Not sure of age but appear to be in good shape.

NOS 4x24,000 uF Sangamo $40 obo

NOS Audio Caps

2x30 uF Obbligato caps $40 obo

can ship at buyer's expense. Paypal for payment please.

thanks for looking,
Scott

Got 2 transistors marked BR and FR

Anyone know what the part numbers are ?

Also transistor marked BE and 8C or HK

For sale: subbu dac v3 with psu. This unit has the Blackgate upgrade. Asking $150 shipped to USA.

I had three 3 different subbu v3 with different caps and this unit is the best sounding.


Thanks

For sale matched quad of sed winged c el34 tubes... tubes are in excellent condition and has seen minimal use. The tubes were puchased frpn upscale audio.

Will ship from chicago
Asking $200.00

Thanks

Hi have 14 surplus tone boards from a product development that I never moved forward with. All boxed and brand new. I also have acrylic cases with them. I am willing to let these all go cheaply at £80 inc VAT and delivery and with the cases thrown in so I can recoup some capital quickly. This is effectively trade price..

Great little boards, measure better than almost any exotica DAC you care to mention. They have USB and Coax SPDIF inputs with phono outputs.

Stefan

Hello,

I was wondering what would be the effect of blocking the vent on the back of a mid bass driver (except reducing the ability of the voice coil to cool down).

I have four identical mid bass per channel so they won't get driven hard and I listen at modest levels.

Thanks.

Does anybody know what CAD program is used to generate the schematics (and possibly the PCB layouts) for the circuits published by Elektor magazine?

One of the members here (Veteran) has schematics on his website that closely resemble the Elektor ones, but I was never able to get from him any answers on the subject.

I thank you in advance for any clues. 😀

I cleaned all switches and pots in this amp checked solder connections all seem fine .

In the 100 series channel I cannot get it to play audio at all .

Any ideas ?

It sounds a bit extreme, although Patrick Turner claims to have been using it at 375V B+. An LTSpice static DC simulation of 375V B+ and 60mA anode current gives a current of 3.6mA running through g2 with a 200R resistor in series. It's a robust tube, but even if there won't be enough g2 current to cause a meltdown in triode mode, what about the g2 to g1 distance and potential arcing, especially when g2 swings with the anode to the other extreme, like 750V peak?

Best regards,
Alexander.

I'm thinking of building preamp as my first point to point project (I built a Tubelab SSE last year), and the JEL76 preamp has caught my eye.

JE Labs Arkiv (up to 2008): JE Labs phono and line preamp

I'm working on a BOM and getting familiar with the schematic and a few things have popped up that I was hoping someone who has built this, or is familiar with the preamp, could help verify for me (mostly about power supply).



1. I can't read the lower rating values of the chokes on the schematic.
Would Hammond 193C (20H, 100 DC MA, 181 Ohms, Max 600v) and 193B (12H, 100 DC MA, 155 Ohms, Max 600v) work?

2. What are the capacitor values on the CRC of the 6.3v heaters? I'm seeing 10kuf 10V?

3. Could someone explain the circuit that floats the ground of the 6.3v heater tap? I'm thinking diodes (and if so what value and direction), but this part of the schematic is not so clear to me.

4. B+ on the power schematic is stated at ~290v, but on the linestage schematic its listed at 280v. How critical is this?



I'm also considering the Wauwatosa Sofrito or Muchedumbre preamps if anyone wants to comment on any of these.

Sofrito Preamplifier – wauwatosa tube factory
Muchedumbre Buffer Preamp – wauwatosa tube factory

Thanks so much for the help!

-Jeff

Here's latest syn attempt that's a bit easier to build because the ports are simple circles, and not jammed into horn corners.

It follows the design pattern of syn7, where the ports are centered under the low-mid driver, with the drivers on the top and bottom horn panels. https://www.diyaudio.com/forums/multi-way/351670-synergy-7-a.html
This design came about primarily to reduce weight, and I've been pleased as punch with the syn7's so thought I'd stick with it.

The reason for this guy, i'll call it syn8, has been about trying to get the low/mids a little further into the horn towards the throat. I'm getting more and more convinced the tighter acoustic centers get the better.
So I dropped down from 10"s to a pair of 8" Beyma 8mc300nd's.

I also wanted a little tighter pattern than syn7's 90x60, so this one is 75x50.

It was impossible to go any tighter and keep the ports centered under the 8" drivers. Narrowing pushes the driver out into the horn away from the throat.
Centering under the cone simply measures better than ports under the outer periphery. I retried a bunch of different port locations including some crazy ones like this smiley face.


Since everything i build crosses to a sub at 100Hz, bass-reflex posts were needed to get the lower end response.
First time trying BR ports on a syn and had to prototype a few port sizes, locations, and lengths, once the driver location and its main port were set.


Uses the same bms 4594he or b&c dcx464 coax CD robbed from syn7's, to get down to 500Hz.
I know they are $$$ but they just solve too many syn issues and work so dang well. Highly recommend either ot them for a syn.

Anyway, here's the box without its yet unbuilt secondary flares.


Here's a top view that shows the bass-reflex ports. Using the top and bottom cavities like this made for surprisingly easy BR port installation. One lid seals up both the driver and the reflex port ducts.



It's sounding so good i have the same dilemma as with other versions...whether or not to add secondary flares.
No doubt will though, just to see.....

Right now, without secondary flares, or a built in stand, or an an enclosure for the CD, it weighs 31 lbs. My guess is those parts will add about 12lbs, because I'll make the flares out of wood, not foam like syn7.
Otherwise I'll just copy what I did for syn7.


Here's the inputs for Mr Waslo's generous and excellent spreadsheet contribution given to us all.


Ports under the 8"'s are 2.125" dia, 6.25" from throat. Notch came in at 480Hz, which was a little lower than hoped, but CD's have no problem there matching all the SPL the 8"s can pull...which is alot 😀
BR ports are 2.25" dia, with centers 5" from mouth edge, and as close to horn walls as possible.
If there's further interest, ask and I'll give port duct dimensions.

Hi all,
I have bought this Vimak DT800 player for it looked to be very similar to the Wadia 16 I recently fixed. A lot of FPGAs, quality build, digital inputs, quality mechanism (CDM-9 Pro).
The trouble is, there is very little info on it.
Please let me know if you have any technical documentation (Service Manual,
/ Circuit Diagram) or have worked on it. It is so new that I have not had a chance to take it apart and examine it, so I do not even know what DAC it uses.
For now, I have no digital output (but input is fine), no display, no headphone output and previous owner assures me it is very intermittent in its operation (although it works on analogue outputs for me now and works very well).
I would even be grateful to find out what remote codes it uses, so I do not have to program Logitech's Harmony with countless codes... I naturally tried Philips remote given it has a Philips mech but it failed to respond. Which of course might be another fault given that half of front panel does not work. 🙂
Here is a little video I put on my uTube channel:
Vimak DT800. Great player about which I know very little. - YouTube
Thanks for an info.
Roman

Brand new, excellent condition. UK or EU only.

Airlink Toroidal Transformer Dual 18V 625VA with mounting hardware | eBay

For the Lindemann "CD-1" and several others like
REVO CDP- 1R - Audiophyl
I need an easy cd player equipped with 15pin SF-P101N optical pickup from Sanyo for troubleshooting.

The Teac models CD-P1440R, CD-P1450, CD-P1820 and CD-P1850
uses the same optical pickup, but unfortunately the 16pin version.

The boom-box model Philips AZ1050 - go to
http://diagramas.diagramasde.com/audio/Philips AZ-1050,1055.pdf
uses exact the same 15 pin SANYO model, but this construction isn't service-friendly.

Who can give me advices ?
I have heard, NAD, Harman and Pioneer uses in several models the 15pin version but the informations about
CD-Player-DAC-Transport List
don't help me in this matter.

Here are some pics:
Èíòåðíåò-ìàãàçèí Comlark.ru. Ëàçåðíûå ãîëîâêè CD DVD ðàäèîäåòàëè èíòåðíåò ìàãàçèí

Hello all.
I currently building the leach superamp, and have a question regarding heatsinks,
I have theese four sinks which measure 300mm long .70mm wide. 63mm high. They weigh 1.3 kilogram each, is one for each channel enough? I read that the low tim requires 0.67 degrees c/w and the super half of it, I have no data on theese sinks, I would like to mount them horizontally on chassis, which decreases proper airflow, as I have four sinks I could use two or channel but that would risk thermal runaway.
All thoughts are welcome
Btw I'm not interested in fan assist.

Wow the new speaker looks good with all those SB Satori drivers

Boards designed and pre-populated by myself. I am asking £20 for it.

i am a hobbyist and does not have deep knowledge, so any help would be gratefull.
my swans m59w blew up because of delivery of excessive voltage and on inspection i can see that there is fault in amplifier chip. the amplifier ic tda7294 blew up and i dont know what to do now. i dont have a circuit diagram so i dont know about all the components that need to be replaced and i cant find a replacement of full board either. what do u guys suggest

Hi all,
I was surfing on the web trying to get an answer to my doubts and an I reached here. I was so happy to see so many discussions about tubes and amps that soon I started looking for a solution to my question.
Unfortunately I crossed a post here… that struck my mind definitely.
The post was talking about to use the 5Z4P tube in place of the 5AR4. I have read the explanations about different specs and I went to read a file that I downloaded elsewhere where I could check all more important Tube’ specs like min and max drop etc. etc. and I finally got what they were talking about.
I do some electronics repair and other stuff but I don’t go so further, I should study more, I am missing a lot of stuff, so I am here asking a tech help even if this for me concern also to the look of my amp…at least it is how it started!
Okay let’s start, but…
Before to read the above post, I started to solve my doubt with a simple math property: if A=B and B=C then A=C. 🙂
I have a Gemtune GS-01 Tube amp sold on the web like this: Hi-End Tube Amp with: EL34 * 2 + 6N8P * 2 + 5Z3P/5U4G (randomly distribute) * 1. Other specs that you can find: This amp uses a 5AR4 tube (or GZ34).
I am not here to talk about if it is or isn’t an Hi-End amp, but just about the rectifier tube.
Anyway, I got my amp with a not said rectifier tube, that on some sites is on the list of the randomly distribute or in the specs: the 5U4C (5Ц4C on tube). I really didn’t get any problems with this tube, but about 15 days ago, just because I had nothing more important to do, I decided to upgrade the look of my amp, so I decided to make it just like I loved it at first sight for the performances and look… I wanted to exchange that rectifier with that giant one on the pic that probably was a 5AR4.
I started comparing some tubes with my math property 🙂 and I found that I could change my tube with the 5Z4P, but this morning, after I received the new tube, I thought that something went wrong: the new one got the same look but… it is still little!!!
The situation today is :
- I have the 5U4C
- I bought the 5Z4P and after the post that I read I don’t know if I can use it.
- I’m still missing the big one tube.
All that I discovered and I am sure I am missing some, that not for specs, but all these tubes are compatible 5AR4, 274B, 5Z3P, 5U4G, 5Z4P, 5U4C,5U4M.
So my questions are
1- Can I use the 5Z4P or I should send it back?
2- Which big one tubes I should buy?
3- Give me an advice: not for the size, what is that best one between the rectifier tubes that my amp can mount?

Thanks a lot to all of you that will help me
See ya

I've done a search for the following but haven't been able to get any definitive answers, appreciate any input:


1. I have some output transformers left over from a kit, they have a 46% UL tap. Schematic and built notes I'm using suggest 43%. Is that enough of a difference to require correction?
2. I'd like to include a Triode/UL switch. Given the voltages present (350ish dc), would it be ok to use a standard 250 VAC switch, so long as the switching is done with the amplifier turned off? The last Elekit unit I built had smaller DPDT toggles, they didn't look like anything high voltage/heavy duty.
3. Is there an issue with using transformer mounting screws as ground points? I don't see it done so assume it may be bad form.

4. In regards to heater wiring, is there anything wrong with crossing between pins to permit twisted wires up to as close to termination as possible (please see pic)? I'll be coming from a transformer right next to the right-most socket, hence the wiring path, I was going for minimizing length and avoiding input signal path.

I am looking to add an USB imput in my dac.

But I can’t found how to connect it.

Perhaps some one has information about how to connect thé I2s wires ?

Thank you, Gilles.

Hello everybody!!🙂

I wanted to make the electra amator loudspeakers, by Sonus Faber..

Is anybody have the original designs for the wood enclosure & the crossover circuits?
I would like to build a clone from wood 😉 !
I don't know if i can make it but i'll give it a try!!!

Thanx a lot!!!😀

Hello to all. I was wondering if increasing or decreasing the value of a cap would help to increase bass definition on my 32 year old Allison 8 speakers. It currently has two 60uF electrolytic caps in parallel for 120 uF. My plan is to replace it with one 120uF metal film polypropylene cap. All the other caps have been replaced with the polypros. Those values are 12, 24 and 5.2uf

Any input would be appreciated


Thanks

I came across these boards, exactly what I was looking for:
4 IN 2 OUT, Remote control and Volume control.

I thought I might give it a shot. It's 85Euro... on the sort of cheap.

I know this is not a lot of info, but what do you think about this thing? Are there reasonably priced alternatives? 😕 A kit would be fun too 🙂

Hello and good evening

I wanted to connect my vintage gear to a DCX-2496 (AES-digital input) and have bought a cheap (16€) converter because it`s the easiest way to change between USB-PC and stereo amp. or tape deck out. Just one lead from one converter to the other.

The converter is working very well from 20Hz to 8KHz but then sharply drops. Thanks DCX I can set a filter to correct the frequency response but this workaround actually is second best.

Amazon is selling a lot of similar converters but all of them are reviewed badly. Same electronic design, different housings - I guess.

My converter has a bit different layout. It has built in a Cirrus Logic 5340 as A to D and a CS8406 as transmitter to Toslink-S/PDIF. Well built, I have to admit.

1. What do you think causes this frequency drop? A wrong input stage design? Where do I have to look for?

2. And - although I would be willing to spend more money, I couldn't find a better converter. No matter how deep I googled.

Thanks in advance and stay healthy

I'll make a custom ADC.The term is 6 weeks. Delivery by a transport company.

The price is 650$ without shipment. OEM version.

The theme on the device: USB ADC on Cirrus Logic CS5381

e-mail 9890175@mail.ru

Great looking 3.5" Audio TFT Color LCD display. Touchscreen controlled, all functions parameters, background images and welcome screen can be set/imported via USB/PC.
Two stereo analog line-level inputs, 5V power supply.
VU meter, 31 band real time spectrum, Oscilloscope, Envelope, Goniometer (X-Y plot), Analog VU meter, Frequency tune..itd.
IMHO great looking display to decorate some DIY preamp or similar..or to make standalone unit. Lying in my closet for couple of year, never used. Was purchased for 80€.

Will sell it for 50€ plus shipping.

Regards

P.S. Display still has protective foil on it, thus some smudge on photos. Otherwise new.

Hello,

it seems a bit odd but I'm not able to find the DAC chip oft this mostly "unknown" CD Player which I did get for next to nothing as a little fun repair project .

It is a Palladium HCD-221 branded model of a not known to me manufacturer.

I was not able to hit any documents or a service manual on the www.

The chips in the mainboard section which is marked "D/A Convertor" seem to be logic ICs from what I found in the data sheets.

Any ideas?

Thanks in advance,
Rudolph

You may have noticed a small change in the buttons on the page.
We are cleaning up the functions of the forum and have changed the Quote/Reply actions a little.

You'll see that the last post in a thread does not have the quote button. It has been removed to prevent the overzealous quoting of the entire post just above.

If you do need to quote the last post in line, you still can. Simply click on the Mutliquote button then click on the big button on the lower left. Easy.
And you can still multiqoute this way, just like before.

Please remember to keep your quotes brief and to the point. No one wants to read an entire post all over again.

I got my ProAc Tablettes in to find one speaker's Scan-Speak D2008 tweeter was bad. So I have two choices:

1 ) Buy and install a stock D2008 tweeter

2 ) Take this opportunity to replace BOTH tweeters with a matched pair of Hiquphon OW1 Tweeters.

Advantage - a SERIOUSLY nice tweeter with greater performance, clarity, etc. Disadvantage: I dont know what - if any - mods the crossover will need.

Opinions?

Information?

Thanks!

Would anyone know the noise figure of a Irf610 operated at about 40ma ?

Looking for schematic of Stax SRM-313 amplifier.

Hello. This is my first post on diyAudio. I am not a "tech", just a guy who has been tinkering with stereo equipment for the past few years and trying to learn what I can. I have been successful at repairing/restoring several Carver pieces and I was able to repair an NAD 2140 and NAD 3140, both which were DOA due to shorted output transistors and a host of other problems. I am just learning to use an old Tektronix 2205 scope.

I am trying to fix an NAD 3020 series 20 with a distorted right channel. This unit has the four main power supply caps in the center of the board. I have confirmed that the distortion is in the amp section. I started by replacing the electrolytic caps in the power supply sections and the preamp and amp. DC offset can be adjusted to very near 0 mV. This made no difference. Power supply voltages seem reasonable. I touched up some suspect solder joints and checked that there were no continuity problems. Some work has been done previously on this unit, namely replacement power supply caps but everything used was under spec so I replaced them. The solder pads on this unit are very fragile. I replaced the 20k ohm variable resistor for the dc offset and I replaced the fixed bias resistor with a bourns 1K ohm variable resistor.

I used an online tone generator for a source and I had an 8 ohm dummy load connected to both channels. The right channel output shows that the negative half of the sine wave is clipped. (sorry, I don’t know how to insert pics into the body of the text so I will attach at the end)

I disconnected everything and I went ahead and measured some voltages to compare to the schematic. Voltages are way too negative. (example, the base of Q610 is measuring about -13V instead of -0.6V) I have included the schematic for the left channel for specs and the schematic for the right channel with proper voltages in black and my measured voltages in red.

There didn’t appear to be any shorted transistors. Resistors seem Ok. I replaced a few just for the heck of it. No shorted ceramic caps. Not knowing exactly how to proceed, I went ahead and changed out Q602, Q604 and Q606 one at a time. No difference. Did the same with Q608, Q610, Q612 (replaced the 2sd669 with KSC2690). No difference. Replaced Q614 (used KSA1220 to replace the 2sb649). No difference. Well then something inside of me said to connect the dummy load again and take new measurements. Surprisingly, the voltages now read correctly! (at zero volume) BUT…. If I put a signal back in and slowly turn up the volume, the voltages quickly go too negative and the output is still clipped.

I have exhausted by limited knowledge at this point. I cannot figure out why the right channel has this excess of negative voltage. It must be something either horribly complicated or dirt simple. Any help or ideas would be much appreciated. Hopefully this all makes sense. Thanks for taking the time to read this post.

35w+35w stereo valve/TDA7376B chip amp. £19.99
100w mono valve/TDA7294 chip amp. £15.99
Valve not included so you can choose your own. 12ax7 or 12au7 recommended or close with 12 volt heaters.


Postage is:
£4.20 to UK
USA and Australia is £17.70
Europe £12.99

Trying to make powerline ethernet work to a room that makes hard cabling very different.

The first try was putting one of the units next to the main junction box. Logically, this would mean the shortest distance between units (if rooms were on different circuits). This worked for a while and LED indicated strong connection, but eventually the ISP cable modem, nearby, got screwed up and required a reboot.

Now trying a more remote location, working but LED indicating poorer connection.

Any insight as to how these work?
I assume the main panel is a bad location because it is close coupled to inductive appliances that hinder its operation?
How did the cable modem likely get screwed up, RF through the power cable or radiated?
Would better power filtering for the cable modem help things or make things worse but putting inductance on the line?

Any help appreciated. TIA

Wanna kick up the power a bit by sub'ing the Pioneer SA-810 6GM5/7868 output stage for the current 6BQ5's in my Dynaco ST35 clone.
So I've acquired upgraded PT- From 300vdc/200ma to 400vdc/360ma, and 4 6GM5's.
Both schema's posted below-
Can I just replace current ST35 output design by retrofitting it's .1uF coupling caps C4 & C5 to the Pio SA810 .47uF's,,, then adopting everything on out??
Thanks,
Jim
ps. what about the anode & cathode resistors on the phase splitter section of the triode driver? 27k & 33k for the medium mu triode ST35... but 47k/47k for medium mu triode 6AN8 Pio design

Addendum-
also pulling out the 470k grid bias resistors and sub'ing in the 100k's w/ -19V supply

I want to build a (relatively simple) enclosure for a Dayton RSS390HO 15-inch driver now that I have managed to build a box that hasn't yet fallen apart for my pair of Dayton RSS265HOs.

It needs to sit up fairly near the front wall and I was wonder whether a Karlson design might work for this?

It also needs to be fairly compact. My other half tolerates the pipeline TL subwoofer I have been playing with but I think she'd rather just have a discreet box sitting there rather than a stormwater sewer in her living room. Cant think why.

Im not worried too much by how low it will go; it's more important that I actually produce something that looks a bit more like a conventional sub.

I like the old-school look of the Karlsons, but am open to anything that's simple (ish) to build and is TL in nature rather than sealed or ported (where I've already been).

The Karlson design appeals in that the driver is within the box rather than having to mount it magnet out in a more traditional TL (like BoxPlan TL1 on Brian's diysubwoofer.org page).

That said, I think a TL1 box might be an easier build than a Karlson and my building skills are rudimentary in the extreme.

Any practical advice would be much appreciated.
Cheers
Peter

Thanks in advance for any suggestions.

Hi all

So after discarding of my old speakers i am now finally prepared for my first “real” diy speaker. I once built one during high school, but with alot less budget and less no knowledge about physics and electronics.
For everything i have until now i used winisd for port and box calc and then i will just calculate crossover by hand.
Planned is a two way for desk use.

Now to my problem:
I havent heard alot of different speaker materials and i dont know how they sound.
Ceramic cones are very new to me, i only heard they have great clarity.
I have the possibility to get two accutons for around 300 dollars for both, from a guy who used them. The model is c173-11-095 the frequency response is very similar to the c173-06-096.
Link: https://www.lautsprechershop.de/pdf/accuton/accuton_c173_11_095.pdf
So im pretty fixxed on this as the mid bass driver.
Im planning to make a bass ported version with a case of around 14 litres.
Low pass frequency would be at 2000 hz and not higher since i need to avoid the resonating area that starts at 2500 hz.

Now, my question is: what tweeters would be a good match for those?
Alu, be, soft dome, electrostats?
What tweeter material besides ceramic would be a good matchup?

If i find accuton tweeters used in good condition i will use those but otherwise they break the bank for me, Im a still a student.

Also if you any particular tweeter for around 100-150 im all ears.
I habe never heard electrostats but there are some accuton 2-ways out there that use them but the ones i saw were around 400 per tweeter...
I could buy two scanspeak R2904/700005 for 370 for both, as dead stock from china. A good price for these as it seems but still breaking the bank.

Thankful for any recommendations 🙂)

I am trying to switch on a source selector relay board using Arduino. The source selector has 12v relays with common ground and +12v are separate for the 5 relays ( I wish it were the other way around). Can I use the circuit below to switch the 12v relays ? Any suggestions?
Thanks,
Dinesh

Hi !
I want to buy a single Esotar T330D tweeter. if you have it please say to me. They can be new or used. Payment via paypal no problem.
Thanks and best regards!

hi guys, i need some info from you experts. i am building a signal cable to connect my dac to the preamp. the dac has only balanced xlr outputs, while the preamp only has unbalanced rca. not to use rca-xlr adapters I enjoy building some nice cables. the designer of the dac told me that the connections, in the specific case of this dac, are: phase + on pin 2, phase - and shield together on pin 1, pin 1 connected to the connector body to the chassis. pin 3 remains disconnected. So far so good, but I came across this Ramm Audio Elite 8 signal cable, which has not two conductors plus the screen, but 3 conductors (Green, red and white(?))plus the screen. how do i connect them? two conductors on pin 2 and one with the shield on pin 1, or one on pin 2 and two with the shield on pin 1?

Hi!
sorry for yet another...
My toroidy 2 x 18V 500VA
has a earth-wire (yellow-green) accompanying the 2 primaries.
Looking through the build-guides as well as sound-au's Power Supply Wiring Guidelines doesn't show this detail.

Do I connect it to the power-connection, to the chassis before the cl60, or after (together with the PSU's ground?)
My instinct tells me to hook it up as soon after the power-inlet/switch/fuse as possible...

thanks for confirmation!

Wondering, host based Windows 10, is there a simple configurable HP filter? I am running the Peace GUI on the EQ, and just knock down the lower two octaves. HP at least 4th order, 60 Hz as my desktop speakers are 3 inch Fostex. They are reasonably flat so I don't actually use any other eq. ( modified and tweeter)

Seems over kill. Maybe it makes no difference, but I am one of those where the less is running the happier.

hi everyone, I wanted to talk about dual head usb cables construction, therefore with separate data line and power supply line. I always use for data rail a certified usb cable in order to be sure to comply with the usb protocol requirements. The power supply rail, on the other hand, I have always chosen cables with a larger section, perhaps ofc and with low inductance and shielded. What I am not clear about is the screen: on the dac connector type B and pc connector type A connected both sides, but on the power supply connector side? i usually use xlr connectors on the power supply. Perhaps it is better to choose an unshielded cable for the power branch, perhaps a quad star ...

Choosing between 3 Troels Gravesen 3way project
1) SBA 761
2) ScanSpeak Discovery 861
3) Jenzen SEAS ER



Plan to use this acoustic for a long time. Medium size room. Music(any genre), movies.


1) SBA 761 (TW29RN-B-8 MW16P-8 MW19P-8)

most advanced speaker technology (satori). What about reliability?

2) ScanSpeak Discovery 861 (D2608/913000 18W/8434G00 22W/8534G00)

newest project. cheapest. will it have the same performance as satori, or be worse?

3) Jenzen SEAS ER (CA26RFX, ER18RNX T25C003)

old project. biggest size. how it would perform compare to others?

I wanted a schme as simple as possible and a power amplifier as easy as possible to make in amateur mode.(as a hobbyist).

I used an SMPS push pull. ( with an transformer from an ATX computer power supply)

With the transformer secondary I directly in series the speaker and a solid state relay (Consisting of two NMOSFETs)

The audio PWM signal is given by an Attiny25 / 45 which also brings a lot of noise. I didn't solve the noise problem.

But I want to solve the following problem: So I use only half the power of the transformer.
When I need to have a positive voltage on the speaker, I waiting the positive pulse from the secondary and the voltage value is made of PWM duty.

I need an H-bridge-like circuit to change the polarity of the voltage, but to work and for positive voltage and for negative supply voltage.

Sure, I could put a rectifier bridge and an H-bridge, but there are too many components, I'm looking for something I can easily do.

Class D amplifier eliminated ultrafast bridge and SMPS filter capacitors - YouTube

I don't have an oscilloscope to show you the waveforms.
Calculated PWM frequency must be at 64KHz, but I didn't measure that, I just know it can't be heard.

Hello,
Everything worked perfectly until one day when I turned on my pop-up light. Suddenly, the player began to run irregularly and both the stroboscope (on/off-button) and the pop-up-light began to flash. I have examined the lamp, there are no short circuits.

It flashes only when it plays (the disc spins). Whan just on, it has a steady light. There is also a clicking sound when it spins. Only off the engine. Not when I roll it manually.

Luckily I have another SL-1200 MK2 so I have tried to connect that player's three contacts to my player with errors. Pitch control, lamp and (off / on, 33/45 / start / stop) parts are in other words ok.

I have also replaced the IC101 (motor circuit). Yes, I now have one for sale if anyone wants to buy 🙂 I have also changed diode 103 (now 4.7V 500 mW) and resistor 307 (now 10 kohm 0.25 W) which many suggest in various forums.

I have also soldered the contacts in the tone arm.

What do you think is wrong? What should I change / do?

Hi - I have an old amp that used to have an optocoupler in an auto mute circuit to operate during a 2 minute warm up.

This is the component:
https://www.tubesandmore.com/sites/default/files/associated_files/r-vtl5c1_2019.pdf

I have been chasing hum and thought it might be one of these so I removed from the circuit, the hum did not change much ( a little bit) but the sound improved so I kept it out of circuit.

I now wonder if I need to put in some sort of equivalent resistor in the controlling / driven side of what is now a circuit missing a component in a circuit.

To be honest I really have no idea what I am talking about, but I have a problem of instability that is occasional and worrying and it's just a logical question - have I left an unstable circuit with a gap!!

Circuit is here https://www.arcdb.ws/Database/SP8/ARC_SP8_manual.pdf

Chuck Yeager passed.


First american pilot and man to cross the sound barrier and WWII hero who fighted in the french sky and won a lot of battles there.



RIP Chuck Yeager.

Hello,

I have a Tannoy TS2.12 dead. No power, no led light. I took the PSU out and I don't have the standby voltage at all. The PCB is double side, very crowded and difficult to fallow the tracks. Are the schematics of this PSU available somewhere ?
In Primary I have 314 volts on big capacitor and nothing on input of KA78R15 which I think is for standby voltage? What can I check next?


Thank you and Kind Regards.

Hi all,
Please let me know if you have any for sale, ideally in multiples of 10 or more.

Cheers,
cv

Hi,

My receiver has started to power off after 2-3 hours of use. Restarting it will give me progressively less time (10-20 minutes) so I assume it's some sort of heat protection. Removing the cover doesn't reveal any dustbunnys or scorch marks

Any other Yamaha power down threads I've seen so far talk about immediate shutdown or coinciding with a volume increases which doesn't seem to be my situation. The diagnostics menus don't quite match the service manual I found, 20.1 thru 20.4 all say "I PRT". A 457 service manual says that means excessive current so bad power supply?


Any suggestions?

Thanks,

Hi. I want to build a low power germanium stereo amplifier and i got a little stuck...
So the story goes like this: A few years back was repairing a vintage radio and had it hooked up to one of my crappy speakers which had a decent bass for what it was and i was really surprised by the "warmth" and power of that tiny amp. I don't know if it was because all i used at the time were cheap class d board or because of the tapped volume control but I liked the sound and I didn't even know germanium transistor were a thing at the time... Then I started to look for a circuit using these transistors (ac187/188k) and I found an interesting amplifier which is riz transiwatt 8 and it uses these transistors. It doesn't have a tapped volume control but it has a tone control.
Here is a circuit:

https://www.google.com/url?sa=t&sou...Vaw1bdam7IFN2Tf_iu8zoPBSu&cshid=1607085821221

Now here are my questions:

1 what do r13 and r14 do. They seem to be trim pots and i don't know how to adjust them.

2 where am I supposed to find 13M ohms volume pot?

3 is there a substitute for ba103 diode because NOS part costs 20 dollars!!!

4 I see that under each transistor it says another transistor name. I think that is other compatible transistor. Now what do I do. I can get NOS parts or use bc108 ? (I already have NOS output transistors)

And finally is there some suggestions about the pcb layout?

Thanks in advance and sorry for the wall of text. Also if anyone has a better circuit for these transistors feel free to tell me.

Hello all.

Im toying with the idea of building a simple IDHT preamp to clear up some spare parts off my shelves.

Im looking for a nice linear IDHT with a lowish output impedance (less than 5K).

I have thought about a 12B4, 6V6, 6Y6, and 1626 tubes.

The amp the preamp would be driving has an input impedance of 10K.

Any recommendations and thoughts are welcome.

Hi, I know very old and cheap speaker. But, I'm interesting about (yes, cheap and old so I can open and disassemble them).



Tannoy mercury series mx1, mx2 tweeters are the same. I have both. I absorbed weak sound level. It's very low I think. I measured empedance, resistance, crossover; everything is ok. Also, I opened one of them, coil looks good.


Now, I newly learned speakers have ferrofluit and if it loose it's viscosity, it can behave like a glue?! Those are very cheap speakers, is there any ferrofluit in it? I could't find anything in internet. If so I will open and clean it. Or cone may be very old.



How can a speaker lose it's volume? There is no replacement. I want to fix them.

Selling four VBO52-08N07 IXYS bridge rectifiers. These are the stout PWS-D package, and turned out to be just a bit too tight for the chassis I bought them for. They all work fine.

$60 for all four, shipped within US. $50 plus actual shipping cost anywhere else in the world.

Hi
I have this amp and I'm adjusting the bias for the two channels and have a few questions I'm hoping someone can answer for me. I bought the amp with a problematic channel but after looking at it I noticed one of the thermistors, RT3 was not in the heatsink. I put it back together and replaced both trimpots with 4 turn so I wouldn't have the sharp adjustment of the 1 turn. The amp voltages and currents all check out fine and I've spent some time trying to figure out the imbalance in temperature between the two channels and have some hypotheses but need to confirm some things first.

1. Does anyone have the FEB parts list that shows component values?
2. What is the "B" value of the 1K & 3K thermistors? 3800?
3. Should 49C at the rear of the heatsink be the target for this amp as listed in the bias procedure?

What I'm finding is the left channel will settle out at about 40-43C, using an IR thermometer at rear top of heatsink, and the right will settle out at 45-47C when the initial power on current is about 1.4A per channel. When the two channels settle, left~400ma and right~600ma. When I trim in the bias to increase drive on the left channel after it has settled and replace the cover, the left settles back in at 40-43C. I do this twice and let it cool but the problem is when I turn it back on cool the startup current has now doubled and the resulting temp comes right back down. I think I understand why the large increase in current when cool is because the secondary opto compensation kicks in after(above 40C somewhere) but it just seems different than the other channel and I can keep adjusting but not really lock in around 46-49C as I would like. It looks like the diff amp circuit will kick in at about the 48C point, based on the value of RT1 being 375 ohms(48C) if it's a B of 3800. Anyway any help is appreciated.
Thanks,
Kevin

Help!
My CD player is Sony Cpd-X55es, but unfortunately, it catchs a trouble now £¬mainly appearance is that the door open and close automatically, and the trouble is some even if no CDdisk be placed , i want to repair it by myself, so i need the circuit schematics and the service manual for X55ES.
Can anybody give me a help. thanks very much!
My mail is kaisa.xiong@163.com or kaisaxiong@hotmail.com
Thanks for your help.

Hello. When i turn on my amplifier the light keeps flashing red and not turning white as before. I cant locate the problem. Anyone have any suggestion? Would really appriciate it

Hello, I am installing a DACT 100K attenuator and the original potentiometer is a four-pin Alps so I deduce that the fourth pin is for loudness, it could be installed since the DACT has only 3 pins

CSRA6620 looks promising, and unlike Zetex this one is a single-chip solution.
As I see I can buy CSRA6620 for about $5 from Arrow, however, Qualcomm makes from that chip a military-like secret. Any ideas?
Documentation | CSRA6620 | Qualcomm

No interest here, so I am deleting the content.

These were made by Tong-sol , with Bendix specks. I have had both , they sound the same. Tested on a Hickok TV7-U, were 36 is low.
test 62 - 66
62 - 62
340$ and shipping
thanks Rick

I have a DC-offset issue on one channel of an Accuphase E-303, and I can't seem to find the cause, so I could really use some help.

Starting point:
All electrolytics are new.
All other components have been measured and checked (several times).
I found only one defective diode: D3.
It works and plays music just fine, and THD is normal.

BUT: As the amp warms up, the right channel drifts from DC offset at basically zero, to about 650-700mV (a rather suspicious value..).
The left channel only drifts around 30mV, which seems normal/reasonable.

Initially I suspected the input stage, but it measures well balanced, app. 100mV on all Bases of Q2 and Q3.
The problem seems to at the Base of Q13 (the PNP driver), which only has about -0.45V when warm, and it should be close to -1.3V.
The base voltages of both drivers change during warm up - they become increasingly uneven.
Please see attached schematic, where I have also noted some voltages.
The rail voltages are all very close to the schematic values.

The question is why? What can be the cause of this?

I have spent quite a few hours trying to find the fault, and have one by one replaced the following transistors (to try something..):
The Q12/Q13 drivers (with a matched pair).
Q4/Q5 and Q6/Q7.
The STV-3H triple diode, and the VR2 bias trimpot.
All the plain signal diodes.
- All the replaced components test good out of circuit, and the DC offset is still the same (but no worse).

I have also tried removing first one output pair, and then the other, but it didn't make any difference.

Seems like it is a simple issue, but it just eludes me, so would greatly appreciate some help 🙂

SOLD SOLD SOLD FS PAIR JBL CINEMA SPEAKERS MODEL 4670

Gently used pair of 4670's, only ever been in a home theater and never saw commercial use. I ran these bi-amplified with active crossover and i do not have the passive network. You'll need a dsp/active xo like a DBX Driverack/Behringer DCX2496 or similar.

Pair JBL 4508 Bass Bins
Four JBL 2226 15" Woofers OR 2035's your choice
Pair JBL 2080 Horns
Pair JBL 2446 Compression Drivers

I'm selling them to make room for pending and future speaker projects.

My 1st post here: hi all of you!

I want to remove ALPS Blue Velvet from my integrated amplifier and I read somewhere that a resistor of the same value should be replaced with (some say in parallel others in series), but I would like to see a simple schematic, if possible, in order to be sure.

The potentiometer is a motorized ALPS 10KΩ Blue Velvet Stereo (RK27112) just as the picture in attachment.

How to do that?
So many thanks for any appreciated addressing!

Hello everyone,

I am new to this forum and this is my first post. I did use the search function for my topic but had no luck, thus I decided to actively ask you guys for some advice.

As title says, I have a turn on/off pop using an Alpine PDX-M12 for my sub.

Some background: I am currently in the process of upgrading my car stereo. As part of this upgrade I have doubled my sub. So instead of using a single 10" Wavecor sub I am now using 2 of them in a CB, wired in parallel (they are 4 Ohms drivers). My previously used Alpine MRV-T757 (used to run in bridged mode to fire one Wavecor sub) was no longer sufficient to power 2 of them so I was looking for a more powerful amp. I ended up buying a PDX-M12 used.

After installing the M12 and connecting it to the newly built double sub I noticed a slight turn on/off pop which was not present in the previous setup. It is not very loud but audible and I would like to get rid of it, if possible.

I searched the net and came across some threads in other forums where people were reporting same symptons but no real solution or clear root cause. Others were reporting no issues whatsoever with these amps. Seems almost like a hit or miss situation with these amps.

So I am really wondering if something is broken in my amp that can be repaired or if this is maybe a design flaw of the PDX series which surfaces only in very particular setups or equipment combinations.

Thanks a lot for your support!

Holger

Good morning everyone, I have a mmats 1100.1 amplifier on my table, it had damaged mosfets irfb4710 and hip4080 which were replaced, I can no longer find damaged parts, however, I connect positive and ground (without connecting the remote control) and the led " default "stays on, there is no overconsumption, what can be activating this protection without the remote control cable?

Just wanted to spread the word on these in case someone is rehabbing their lineaum two ways.

They have been in storage most of their life and I recently applied new surrounds.


Pair of original 5" woofers radio shack RCA 40-5007 | eBay