I've changed the op amp to a OPA1652 and added a gain switch and now I'm thinking of decreasing the value of the emitter resistors and removing the negative feedback capacitor.

I know that decreasing the emitter resistors too much leads to thermal runaway because it increases idle current, but how much can I decrease them by before that starts to be an issue?

As for the feedback capacitor, I simulated it in LTspice (5R emitters) and it appears to still be stable even without it.


Removing the gain resistor also appears to not trouble the circuit at all, so I plan to use two gain levels of x1 gain and x6.1 gain with a 5k1 resistor.


Are any of these things a bad idea? Please advise!

Hi all

I’ve come across some 6N1P tubes described as 6N1P-V I believe they’re from the old Russian Reflektor factory. Does anyone know much about them? Interested how they would compare to the other 6N1P tubes.

Hi,

Need about 10 pieces of C2M1000170D for a project. Happy owners that would like to part with those parts are very welcome to contact me with their offers.

Best regards, Kovaxant

Importance of driver slew rate and how to define it

An amplifier's speed is defined by the parameter "slew rate". It is measured in volts per microsecond. The figure varies from amp to amp, but for home audio amplifiers it usually ranges from about 10-100 volts per microsecond. Older amps are on the lower end of the range and are considered slower.

The higher the frequency that needs to be amplified, the higher the minimum slew rate must be.
The higher the amplitude of the highest frequency, the higher the minimum slew rate must be.

It's not enough to be only fast enough... For example, CDs sample rate is 2x the maximum reproduced frequency (disregarding filter). This is done to cover the 2 directions of movement in one cycle. It is not good enough for an amplifier to be able to raise and lower its voltage fast enough to match maximum frequency at the maximum amplitude. If a sine wave were applied to the input, the waveform on the output would be a triangle - not good. Amps slew rate should be at least 10x this amount to be considered acceptable. But the faster the better. Reaching the point when the waveform is not distorted is the goal. Amps don't have the advantage of CD players, which, when outputting their highest frequency, take 5 points and interpolate a sine wave (one of the reasons CDs sound unnatural).

If the slew rate is too low, lower frequency transients are too quiet and high frequencies are clipped to lower amplitude triangle-shaped versions of the input - it doesn't sound good.

I think a woofer's slew rate can be measured by applying tone bursts of increasing amplitude until compression unrelated to voice coil thermals results. Put another way, this is when the cone is lagging behind the signal because EM coupling is too weak. BI is a factor, but not the only one.

Things like BI, Mms, radiating area, frequency, and probably others would need to be used to calculate it. I don't know enough about the physics of it all to come up with exactly how, but if we could have a discussion about it, collaborate, we could come up with a new driver parameter which defines transient response. The higher its value, the more true to the input its output. Thoughts?

I think the frequency that is used should depend on the driver's size, cone diameter specifically. Since the measurement needs to stay away from xmax and beaming, I suggest wavelength 1.5x cone diameter. So 600hz for a 5 inch, 300hz for 10 inch, 200hz for 15 inch. This way up to 130db can be tested with 4mm xmax (basically every driver is compatible)

I am building a Lii 15 with dual 18s per side in open baffle. I would like to use a MiniDSP HD or DIRAC, but I am not sure if it is going to work. I think I will cross the 18s at about 100hz, and would like a subsonic limiter on them too. I think it would work better to have one 18 20-100hz and the other one 20-60hz. The 15 would take it from 100hz up.

My question / Could I do this with the MiniDSP 2x4 if I used a resistor to limit the one 18 to under 60hz? Would it cause issues with the measurements? Is there a better way to go here? Could I use 2 MiniDSP's? In that case, I would want to use the leftover 2 outs for a center channel. Could the unit manage controlling just the one 18 from L/R and also the Center?

I hope the questions are clear, and I would really appreciate any advice!

Hello, I’m repairing a Yamaha CR-2020 and performing the service bulletins. It recommends replacing the two regulators TR712 and TR715 as the originals get too hot. The recommendation is to use the TIP41C. I can place an order for them if needed, but I have a few dozen each of the MJE15032 and MJE15034 and would much prefer to use those if they’ll work or be even better.

Thoughts? Would it be better to use the 15032 or 15034, which of the two would be a better fit?

Dan

Hey all. I’m wanting to not use m much wood in my next project (had to build too many shelves... need a break from wood) and was thinking of mainly using black steel plumbing pipe for an OB project.

Anyhow I was going to mount the drivers by the magnet by gluing them to pipe flanges but thought having a huge chunk of ferrous material right there might not be so great for the driver. You guys have any thoughts on this? Will it make a difference at all to driver performance? I’ll measure response in the process of doing the active crossover, so any bulk shifts in response are fine, just don’t want to introduce things I can’t correct for.

Thoughts?

Thanks!!

JVC made a small driver with a wood cone (birch).

I saw this in a magazine a few months back, it's interesting to say the least.

JVC WOOD CONE DRIVER

I have a vintage Dynaco Stereo 400 that exhibits an annoying hum. It's only noticeable at quiescent (idle) and at low listening volumes. I don't know the frequency of the hum.

If I measure the power supply output, the rail is 150 volts DC with an AC component of 160 millivolts at 120 hertz. So the ripple is 0.106%.

Questions:
1) Is the magnitude of this ripple enough to cause the hum I'm hearing?

2) What is an acceptable level of ripple for an solid state audio amplifier?

3) If I replace the large capacitors, will this cure the hum?

Thank you all.

Gary

I measured the signal levels off some test discs.

My cartridge is Denon DL-103 specified 0.3 mV @1kHz @5cm/s

I use a SUT Lundahl LL1678 with 1:16 turns ratio. The reflected load is 47k / (16x16) = 180 ohms.
My preamp has about 50 dB gain @1kHz (a bit too high).

My first test disc (MHV - Hungarian Disc Co.) has a 80mm/s 1kHz reference track, where I measured 4.20 V output. This scales down to 2.63 V @5cm/s. Divided by the phono gain 315 gives 8.35mV. Divided by the SUT gain 16 gives about 0.5mV. This is much higher than the specified sensitivity of the Denon, which I don't understand yet.

Another disc I tested is the HFN&RR 300Hz "torture" tracks:

+12 dB - 6.19Vrms
+14 dB - 7.62Vrms
+16 dB - 9.40Vrms
+18 dB - 12.40Vrms

A good phono preamplifier must have at least that high overload margin. Multiply the above RMS by 1.4 to get the peak 17.5V, 35V peak-to-peak. With a more common phono gain 40dB this is relaxed by a factor of about 3, that is 12Vpp. Did you expect it?

Just for fun and my own personal education I thought I'd build my own LT4320 based rectifier for my test bench. Looking at the LT4320 manual it looks pretty straight forward. Just make sure you choose MOSFETs with a low RDS on and you're good. The only thing that has puzzled me a bit is the calculation of C Load. The manual seems to talk about C Load in thousands of uF when I've seen much lower values in other designs here. As a non-EE what am I missing?

Regards,
Dan

CLOAD SelectionA 1μF ceramic and a 10μF minimum electrolytic capacitor must be placed across the OUTP and OUTN pins with the 1μF ceramic placed as close to the LT4320 as possible. Downstream power needs and voltage ripple tolerance determine how much additional capacitance between OUTP and OUTN is required. CLOAD in the hundreds to thousands of microfarads is common.A good starting point is selecting CLOAD such that:CLOAD ≥ IAVG/(VRIPPLE • 2 • Freq)where IAVG is the average output load current, VRIPPLE is the maximum tolerable output ripple voltage, and Freq is the frequency of the input AC source. For example, in a 60Hz, 24VAC application where the load current is 1A and the tolerable ripple is 15V, choose CLOAD ≥ 1A/(15V • 2 • 60Hz) = 556μF.CLOAD must also be selected so that the rectified output voltage, OUTP-OUTN, must be within the LT4320/LT4320-1 specified OUTP voltage range.

Click to expand...

Looking for a few metres each of red, black / blue and white for power supply wiring.

Can't seem to find supply of small runs of decent wire in UK. Ebay has silly prices pre metre.

Please PM. Thanks in advance

I got an old Technics amp with an interesting "direct drive" turntable from a friend, fully working, nothing special.
On the rear it got an "external unit" input and output that is linked out, what is that for?

If I remove the links, there are hardly any sound, not even on the headphones.

I’m still looking for the best choice in a portable (1-man carry) sub, that can handle DJ gigs as well as rock bands. IMO, the QSC KW181’s suck donkey balls.
The BR dual 12’s I just bought are absurdly bad when pushed, and not nearly efficient enough.

After going around in massive circles, I've actually come around to considering passive, horn-loaded subs. It's far from what I want in many ways, but it might in fact be the best compromise.

I've been looking at the Danley THMini15. I could probably handle a pair of those, but I'm a bit hung up at the -3dB @ 50Hz rating. I know folks love those boxes, and maybe that’s deep enough, but it scares me without actually hearing them.

The JT Growler looks really good. Flat to about 40 Hz, but they don't make them any longer. Also, the thought of just two 12” drivers handling all my LF is REALLY scary.
that just doesn’t seem possible. Still, that might be a design to shoot for, yes?
=================================================

### SO:

I have to also consider Chris’ “Teeny tiny PA 15" subwoofer.” From the looks of the thing, I could manage for of them in my pickup truck, which is lovely.

- BUT WHAT ARE THE SPECS? - Size, weight, freq response, maximum sustained output? Power required to reach that max output?

I looked at the original thread for this design, but it’s over 100 pages long. You gotta’ be kidding me… I assume the design went through some changes along the way.

Chris, can you give me a simple update, regarding the final version?
(Construction, and specs.)
--------------------------------


Also: Can anyone who’s used these give there opinion on sound, output, and how they work in various contexts?

The thing is, Maybe I won't like the "clean" sound of a horn, anyway?

I've read that the distortion generated by BR designs actually makes them seem louder, and I need a s much volume per watt as possible. - I have both a rock band & a DJ service, and need to use the same rig for both. (And need to carry it all myself. And need to tun on one 15a service, including lights... You know the deal. )

Has anyone used Chris’ design for DJ applications?

I know that people have mentioned using film caps as a replacement.

I do not have that much room in this amp to mount 6 caps on end

These are the 10uf 250volt bipolar caps .

I can get 10uf 100 volt bipolar caps locally .

Wondering would the 100volt caps work or are they very likely not to survive?

Or can I use 2 polarized caps and make a bipolar cap ? Say use 2 22uf caps connect the negatives together and solder in both positives to the board ?

Presenting thread here: Old Soul


Schematic and pcb screenshot post #1 , plenty of pictures after .

Tips and Tricks thread - will open, sooner or later

Reading entire thread is advisable , same as inquiring any technical question there : Be sure that you are aware of all things electrical and mechanical !

Germanium thingies- still available on fleabay or here and there; I have some 2N1099 and 1T813, will try to obtain 1T813 in quantity, in time
Taking these from me - matter of arrangement via correspondence, what I have is going to be tested, in any case and only in that way I can send them with kit
Anyhow - Old Soul Bip ( SI Bigun instead of Ge one) is equally interesting and worthy toy



Pcbs are made for UMS , mounting directly to heatsink


Do not hurry - read , think , ask and only when you feel that you want it and can make it , proceed ...... advice which I'm finding applicable on practically anything .

For anything else , write either here , send PM or directly to >zenmodiyaudio@gmail.com<

Prices are mostly dictated with small scale nature of operation (as always is case) and time/work involved in matching and soldering little buggers.

For ordering , contact me at above written e-mail addy .





Kit options :

Option 1.
- LCH pcb ,
- RCH pcb ,
- all smd buffer JFets (Toshiba 2SK2145BL) presoldered ,
- smd precision CCS chips presoldered
- all smd caps and resistors presoldered ,
- 4pcs of 1uF MKC caps (for important bypass positions) enclosed.

Full price , including Paypal fee and P&P for registered shipping all around the Globe - 135E

Option 2.
- LCH pcb ,
- RCH pcb ,
- all smd buffer JFets (Toshiba 2SK2145BL) presoldered ,
- smd precision CCS chips presoldered
- all smd caps and resistors presoldered ,
- 4pcs of 1uF MKC caps (for important bypass positions) enclosed.
-all multiturn trimpots
-output N channel mosfets , 2 pcs , IRFP240
-cascode bjts
-optocouplers
-all electrolytic caps (all Panasonics ,except Elna Silmic II for one signal route position)
-one-pin sockets for special resistor positions
-all (MF 600mW) resistors
-T0220 heatsinks - 4pcs
-etc.

to recapitulate - everything what goes on pcbs , excluding signal xformers and pcb/mosfet mounting screws/nuts/washers ; again - Ge being matter of arrangement

Full price , including Paypal fee and P&P for registered shipping all around the Globe - 185E



If I have everything in drawers in moment of order , can ship in a week time;
If I don't have any of normal parts in drawer , shipping could be delayed up to 3 days;
If I don't have pcbs in drawer , shipping could be delayed up to 2 weeks;
If I don't have most critical part for getting in my neck of wood - CCS precision chips , shipping could be delayed up to 3 weeks.
All in all - you all know that ZM is slow, but inevitable

Handy Addendum (in short : HA!):

-Cap Bank pcbs - set of 2pcs; dual rail, CRC (pads, if you want differential CLC), snap-in up to 35mm Dia, resistor and pads for LED, position for 10mm NTC connecting Audio GND to chassis;
-NTC pcb/ FW style Soft Start - set of 2pcs; each having place for 2 independent NTCs;depending of arrangement of primaries of Donuts you're using. you'll need either one pcb for two Donuts, or one pcb per Donut

HA! set is 25E more

see pics for HA!; lazy to search do I have photo of NTC pcb, but who cares

Hi folks,

I have a number of tubes that I cannot identify because the main print has warn off, but I can see the manufacture valve ID and date codes. These are Mullard valves (mostly radio/TV) that I found really cheap.

This as been useful for identifying dates MULLARD VALVE ETCHED CODES - HOW TO INTERPRET THEM – MULLARD MAGIC

I'm looking for a list of codes which matches the manufacture ID to the valve model number.

For example, these are given in the above post. But I cannot find a general list with 100s of codes anywhere!

Xf2 represents an EL34

k61 represents an ECC82

f32 represented a GZ34

Im searching for some good shematic for loudness control.
And yes,i know that part of HIFI world is against loudness control,BUT,when you have small kids,and lots of job trough the day,and listen music at night at low volume,your ears desperatly want more bass and more highs.
So,i want to instal a switch-controled loudness option to my integrated SE KT88 amp.
Any sugestion for shematic?
Thanks!

Hi,
just curious if someone seen the tone control (Bass, Treble) circuit without capacitors? When opened for fixing Cambridge Audio A1 mk3 I could not believe what I saw...
Did CA invented new tone control circuit which does not require 2 pairs of capacitors and resistors for bass and the same for treble?

Kes

Simple question. What would you use for a basic regulated DC heater supply? Right now I need about 2.5A at 4v but it would be good to have some general ideas.

AC isn't possible since I'm using dropper resistors from a 6v transformer and possible tubes to be used are 4v but have different currents, so the dropper resistors give different results.

I assume an LM338 is a simple solution. Do you need the input and output caps in the attached circuit, or could it be simplified if supply caps are inside 6" (says so in the data)? I'd be using a 6v transformer.

Using online calculators, with a 240R in R1 looks like you need 520R in R2 for 4v. Not sure what wattage though.

Suggestions for a heat sink size for 2.5A out?

This is my first post!!
Thank you all in diyaudio, many times you've solved my questions. Now it's my time to post mine here.

So I'm trying to make a modular preamp and power amp, the preamp cranked up outputs 1.1V peak (0dbu), and I want to make this signal to go 120Wrms (8 Ohms) using some power amp IC (I've chosen the TDA7294 cause I kinda know its datasheet but if you like another one better, tell me!)

I've made my research and I think that making a brigde setup +/-24Vcc, 40 linear gain, 29dB ,I should be able to get to this level. But what if I use the FX return? Then I could go much higher and then I risk blowing up my speakers.

Can anyone give me some advice? Thank you all in advance

ps. Cabinet I plan on using: Harley Benton G212 Vintage Vertical – Thomann Espana

Hello,
I have a Krell KSA 300s in a 110V Version.
I live in Germany and would like to use ist with our 240 Vortage.
Do I need a step down Converter, or does the transformers has internally a 240V provision that I can use?
Any help is appreciated.
Greetings from Germany
Günter

STM32G071C8T6 let out the magic smoke and there is 37 weeks lead time.

Anybody got a spare? I need STM32G07x in 48 pin LQFP.

Hi all,

I need some help with buying a budget DAC for aprox 200$ as replacement to soundcard.


First, i plan on using it to connect it to a tube amp. Lineout will be RCA interconnect.

Source will be a PC. MP3/FLAC/DSD and YT


For other features, i really dont care, focus is on sound quality.
Maybeee i will connect headphones to it, but its not a priority.



My choices are boiling down to following models.

1. Audioengine D1
2. FiiO K5 PRO
3. Topping E30


I do like first two options, anyone had some experience with them ?

Today's stupid question.

I know I can find a uber expensive programmable AC+DC capable power supplies. I just take my $4-6 grand in cash and throw it at a few companies and out pops a nice piece of lab gear. Not happening any time soon.

Not just any unit, either. Something in the ~+2-3 kilowatt range of output.

We know that high power class d sub amplifiers are around for peanuts in cost. even ones that can go up to about +1khz sine, and be about 1500 watts into a 1 ohm load, are available for under $200.

But it needs to be able to do DC at the same time, if required. I know I've got a (potentially) bridgeable but definitely DC capable power MOS-FET amplifier here (literally DC to about 100khz), but I'm not sure I want to stress it and take a chance on it going boom. It's a nice amp!

so, anyone aware of what might fit the bill? Stuffing a few boards is certainly not a challenge, and far preferable than the huge cash outlay. I've got many methods of getting power to such a circuit or board set, so that's not a big deal. I've got a few SMPS 80 amp/12vdc power supplies that can be paralleled, and so on. Meaning, modding a car amp that is suitable to the task at hand.

This is not my wheelhouse, for the most part. I can fake it like the bear dancing, but no tests at the end of the day....thanks...

Realistically, the back end can be a modded out power amplifier of suitable build and capacity, possibly with custom power supply. the front end can be a programmable signal generator. I'm looking or functionality at this time and I'm not too worried about losses.

ie, modded car amp, if one can actually do DC with enough power and efficiency and not catch on fire.....and then a set of SMPS based parallel 12vdc power supplies adjusted up to about 13 VDC (they have sense capacity for sharing, IIRC-- they are 1kw Dell server units)...and then a programmable siggie at the front, with a smattering of metering thrown in for good measure. IF class D amps can be made to do DC, and I'm sure it depends on the individual design..if so, then the whole thing is quite doable with other resources I have in hand. I'd just need to procedure the specific class D amp to beef up and mod out..

Lets just say I'm ignorant about one particular part of the question I'm asking. whether or not class D amplifiers can handle DC output as a norm or in exceptional cases with specific designs, or not..

Since it is about avoiding DC at all costs in audio amplification, one seldom sees any DC ability mentioned, as in never. As in no data, not even in the fine print. What idiot would want DC? (I raises my hand...)

But someone must have some understanding of this aspect ...and I don't want to spend two weeks or even two days.. digging through all the available data to find what I'm looking for. Which is a simple declaration, or clarity.... on what class D can do in the DC+AC department. I strongly suspect Class D is fine with DC but the audio package involved must be beefed up in some specific ways, if it is to be high power class D, and that any controller chips (front end) must also be DC capable and so on. Just a guess. Seems reasonable.

Any ideas?

I'm interested in building a FAST speaker, essentially a 2-way with full-range doing the mids-treble and a supporting woofer underneath. I was thinking about a bipole design for the woofer - they don't seem very popular anymore - too many issues with them ?

Hello

Class D Audio Using the PE29102 driver IC

here reference design

https://www.psemi.com/pdf/app_notes/an72.pdf

Class-D Audio Amplifiers


GaN FETs Devices for audio applications. coming in the market.

GaN FETs are preferred as the switching devices because they offer significant advantages over
MOSFETs. Because GaN FETs are faster, smaller and do not have a body diode, they have fewer switching
losses versus conduction losses, resulting in superior linearity and efficiency


Does somebody already have expereince ?

NOT CURRENTLY FOR SALE

Shipping:
€13 within Ireland,
€25 to UK, Netherlands, France, Germany.

I'm working on a mono WAW system with a Scanspeak 10F8418G10 in a 1.2L sealed enclosure covering about 150Hz and up and a TB W6-223S run by a plate amp doing bass duty. While I'm generally pleased with the sound at the normal 80-85dB listening level, I'm wondering if a 200uf cap would let the 10F perform even better.
The problem is space - finding room for such a film cap may not be possible. Does anybody have a recommendation of an electrolytic that wouldn't be an insult to this special little driver?
TIA, Karl

Hello everybody.
I would like to know from the experts if it is possible to realize the following thing and what problems or advantages it entails.
current DAC output stage instead of the I / V converter, immediately following the passive line crossover filter driven by current instead of voltage, then current-current power amplifier and finally speakers which are consequently current driven. Starting from the DAC output, everything is driven in current.
bye thank you

FS Pass ACA stereo kit. No power supply and transformer.

Price is 75 Euro for stereo - 2 channels.

I can ship only in EU. Shipping price is 20 Euro.

Please send me a message for more details.

Picked one of these up for $10 that needed the input jack repaired, figured the box and
chassis would be worth it for a cheap tube build.
The front panel layout is good for a rebuild with a clean and overdrive channel, bass, mid,
and treble controls and a reverb control. There is a small reverb tank mounted to the chassis.
It has a very cheap looking 10" speaker, at least it is a decent size.
The baffle board is 11.5" tall and I think that if a notch were cut for the frame of a 12"
speaker might drop in and then fit - not sure. I strongly prefer a 12".

Fixing it stock for now. Turned out the PC board was cracked right at the input jack, so I
bridged the cracks with buss wire which fixed the amp - it works!

Pair of 3300uF/50V caps in the power supply, TIP41/42 (6A, 65W) output transistors that
are too small in my opinion. Many JRC4558 OP amps.

The clean channel seems weak with the tone knobs at 5, turning the mid and treble up to
8 helps a lot with volume. The reverb seems very weak with the guitar signal but bumping
the case makes a crash from the springs. Reverb tank says 2K input and 2.2K output Z.
Must be difficult to get enough drive from tiny OP amps. Perhaps it needs a recap?
Overdrive channel is very loud.

I've been working on several small SS practice amps and prefer a Fender and two Peavey's
that I have. But the chassis should work fine for a tube rebuild, perhaps even use the
reverb spring.

Anyone know if the weak clean channel and reverb are typical of this amp?

Anyone have a schematic?

never built something with these. new in box . 75 euro per unit

I discovered this series of Speaker Design courses on Udemy recently.
I’ve read many books on loudspeakers, and built half a dozen kits from experienced designers, and recently did my own design with the Purifi midwoofer.

I wish someone had done this 20 years ago when I got started… this covers theory and practice, with a discussion of pros/cons of doing things.

Big ups to Marcus for creating and sharing such useful video content and step by step process to actually building your first 2 or 3 way speaker.

For the price of just a pair of tweeters:

Cabinet selection and design-
Acoustics 101 : Speaker design basics and enclosure design | Udemy

How to take measurements-
Acoustics 201 : Loudspeaker measurements | Udemy

How to design crossovers passive crossovers-
Loudspeaker engineering : How to design speaker crossovers | Udemy

Highly recommended!!

This is very good condition comes with a swag man linear power supply.No original box but will be well packed for posting.Looking for £385.00+£10.00 postage to UK only.

Hi there

I have bought a heat air gun for soldering, beause it needs to be not expensive and good quality I did buy this one on photo.

It is very good quality and it heats very well, I remove a chip very fast and easy.

worth by it, I think it is almost as good as a professional like hakko.

I need because in winter I go start build something.

Ohh yes for etching and using negative film, here some nice read stuff, a simple withener find here or in supermarket do work as a developer.

OxiClean - OxiClean™ White Revive™ Powder

read pdf also.

https://sparks.gogo.co.nz/dry-film-tips.pdf

regards


regards

hello to all

I purchased a pair of 3 way SD OBS speakers. ( midrange open baffle , ported bass )

seems a previous owner has removed the original xover, and simply fitted;

see photo attatched

1 x 2.2uF cap to the ribbon tweeter. ( 9khz xover )

Cap ( 126uF ) + 4.7 Resistor in series directly to the mid

nothing at all on the bass driver

I dont understand the cap + resistor in series, as for for a simple RC filter, the cap should go across the drive unit.


there are actually 2 caps in parallel, 112 and 14uF , connected to the resistor 4.7 then straight to the mid driver.

these 112uF poly caps are pretty expensive at £ 50 each, I mention this, as Im curious why someone would buy such expensive caps and then create this incorrect xover?

I have seen the xover circuit diagram for the SD1 model, ( larger non open baffle version of the OBS ) and was wondering if I could use that on my speakers.... I know theyre not identical, but Id imagine cant be worse that what Ive got already?

[ the drivers are:- Monicor RBT-180 ribbon tweeter , Dynaudio 5.25" mid ( dont know the model / no labels ) Audax 6.5" paper cone woofer ( dont know the model )

any help greatly appreciated

Any comments? measures +/- 1.5db from 2.5K

https://au.element14.com/mcm-audio-...ome-tweeter-30w-rms/dp/2827683?st=mcm tweeter


Seems ok to me, on par with $20+ domes... has ferro fluid


Not sure on that second bump in the zma

Hi Folks,

I am looking to purchase a 1" bullet shaped dust cap and wondering if anyone can recommend a possible source as can't find anything on ebay/amazon that works.

Many thanks

Luke

Hi friends

I want to build an active crossover sound system with chip amp for my living room. I know others discrete or tube amp sounds better then chip amp but chip amp is easy to build and compact and some chip amp sounds really good.I am puzzling to select by which chip amp i can starting.😕 I have already in my junk box LM3886, LM1876,TDA2009A,or i can manage any part no.

Hello Everyone,

I’m thinking of building a box to house main filter (using John Risch’s design), plus a DC blocker (using Rod Elliott’s design). This will sit between the mains from the wall and my solid state amp.

Question is, from the mains from wall, should the DC blocker first or the main filter first?

Any thoughts much appreciated.

I have a prestine show-car condition amp on my bench for a customer. This amp is of course using SG3525 with HIP4081 in H-Bridge.

It won't power up. The current draw is 0.1A.

The SG is putting out clean drive on pins 11 and 14:
Just for good measure;
SG3525
1: 0.139
2: 2.585
3: 0.022
4: 0.176
5: 2.067
6: 3.783
7: 2.062
8: 4.92
9: 6.04
10: 0.002
11: 5.77 (Square wave)
12: 0.002 (GND)
13: 13.41
14: 5.74 (Square wave)
15: 13.41
16: 5.19

No BJTs/FETs are measuring shorted. Board looks perfect. Hesitant to remove it from the sync atm.

Absolutely zero drive at the PS fets.
Should I measure the pins of the HIP4081? Another component? Or is this amp a 'bust'?

Octopart search for HIP4081: HIP4081 | Octopart

Looking for a distributor for Eton Drivers.
Blown- 7-380-32HEX.
Need- 7-300A8-32HEX.
Want- 7-212/C8?32HEX.
Anybody got an idea?

Thanks
Don

I have purchased two Axiom 300s that look like they have good cones but the paper surround is ripping along the ripples in the surround. It has been repaired poorly before I purchased them and the repairs are failing.

I was thinking about reconing them but cannot find a cone worth using that would be considered a Full range cone.

The original design is a curvelinear cone that is over 3.25 inches high from VC to edge and is lightweight along with an aluminium wire VC. All recone kits available are heavier like the Celestion cones.

Does anyone have any suggestions about whether to recone or replace the surround and where to obtain the impossible dream.

Thanks in Anticipation.

Hi all,

I've lurked in the forum but this is my first time posting. I searched around for info on this stuff but didn't find anything - if there's something I've missed, please let me know.

I'm in the process of modding my Zu Omen Dirty Weekends mkII. I've braced the cabinet near the drivers with dowels and will eventually upgrade the drivers with the Zu 103s and the tweeters with some Radian 475s. I've seen some folks recommend coating the inside of the cabinets with something like Acoust X. I was curious if that delivers a noticeable change. There's already foam bricks directly behind the drivers, so I'm not sure if adding a coating of dampening material besides that will make a huge difference. Thoughts?

Thank you.

Hello,

I am doing a redesign of the crossover for my speakers, because I was a total noob who had no idea how to design crossovers when I made the pair currently in the speakers.

I did get some great help here in the forum so the original isn't terrible, but I have learned a lot in the 4 years since making the first pair...

So I just would like some advice on the new design.

Here is the original design:




And here is the redesign:



The new design has some compensation for baffle step, along with some padding too...

Do you think there will be any improvement in sound?

Thank you for checking out my post, and possibly giving some help/advice...

Hi
All
Which is a better driver please
The Visaton W300-8 or Peerless 830669

The Visaton has a foam surround which I have read can rot and does not last
The Peerless has a rubber surround which seems better

From reading here people have had good results with the Peerless driver

The peerless has a higher spl
This is going into a REL Qbass enclosure


Please help
Thanks

FS : (SOLD) EDCOR CXSE25-6-3.75K output tramsformer pair

(SOLD)

FS : pair of Edcor Single End output transformer CXSE25-6-3.75K, 25W, Primary 3.75K, Screen 40%, Secondary 6 Ohms.

New in box, never used.

Asking $190, free Shipping.

Only ship to lower 48 USA states.

I have had a Krell KAV-250CD player (coupled with a KAVP/A combination) for nearly 14years. In that time I have had a few problems with the player reading certain discs, either not finding the TOC or not being able to play the disc even after the TOC has been located. It has never been able to read copies. Over the past few months this seems to have got worse. Having scanned the web I think it must be a Mk1 unit; I'm not sure about the transport mechanism but it certainly has a Sanyo SF P1 laser head.

I'm wondering whether it is possible to replace the mechansm with something a little more reliable/robust. Does anyone have any advice or experience of this? I does look as though its a fairly common problem with this unit. I'd prefer not to have to replace the whole unit if at all possible.

Any advice would be greatly appreciated

I don't know if this is the correct forum but I want to ask, is there a potential problem by stuffing the rear holes with cotton "balls"? I mean can I have overheating from the amp?


For those who are wondering, I got those the other day but now I'd probably want something the between the JBL One Series 104 and these Swans D100 in terms of bass. The Swans have too much bass and the JBL not enough.


In any case, I had also turned down the bass button as well.

Does anybody here know Seventh Circle Audio Forums? Who runs that place?

I have not been there in 16 years. There are no new posts in 6 years. I got-in quickly using a super-old password which was exposed in one of the big hacks. (Home Depot? Bat? VISA? they run together in memory.) Attempting to PM or post throws a slew of errors.

This GB close at 25/Feb,thanks!

Hello DIY hobbies

Some people was asking about the TPA3250 board purchasing after they review the IEEE Spectrum:
build-your-own-professional-grade-audio-amp-on-the-sort-of-cheap
but, unfortunately, this board had been end of life, so it won’t be available anymore. having a chance to let these DIYer who interesting on the TPA32xx family amplifier for their DIY project. Now we are planning to setup a group buy on TPA3251/3255 amplifier board and ADAU1701 DSP Pre-amp board.

Description of activities:

1. Must be more than 50 orders, to get a good discount on shipment cost mainly
2. All order will ship by DHL, excluding customs clearance charges
3. Limited to 3 SET maximum per order
4. Discount detail:

• $5 discount for 1st SET
• $10 discount for 2nd SET
• $15 discount for 3rd SET
• 1 pcs free interface Board per DSP Board order

5. Be sure to follow this thread with below format

• DIYA Nickname _Country (to make sure DHL shipment is acceptable)
• Board P/N _ Q’ty

6. Please send email to 3eaudio@gmail.com with following format for order and shipment information:
Email title:
Group buy: Board-1 P/N | Board-2 P/N | Board-3 P/N
Example: Group buy: EAUMT-0140-2-A | EAPST-0200-36-A | EDSP-1701-24-A opt1
Content on order info:
Board-1 P/N_Q’ty
Board-2 P/N_Q’ty
Board-3 P/N_Q’ty
Payment account (PayPal only)
Shipment address (as detail as possible):
Receiver
Phone number
Postcode
Street, Road, City,
State, Province,
Country

7.Group buy timeline

8.Group buy product list and detail info,refer to attachment
View attachment Diyaudio_Group buy_TPA3251_55 AMP_1701 DSP Board.pdf

Hi All,

I am crawling the WWW for days now, often being redirected to our Diyaudio site, but whitout finding the answer I am looking for.

I bought 10 each of N and P Sanken Darlington transistors to replace some TIP142/147 in an amplifier output stage.

There's 1 pair of paralleled devices each (N/P) per channel.

Did anyone match similar devices with any of the suggested methods that are floating around ?

Thanks to all!

Max

Ok, I know they're probably rubbish, got to be for the price, but I only want to drill a few holes in aluminium, steel occasionally. I've had enough of doing it "freehand" and making a bit of a mess. Has anyone used any of this junk or can recommend something (slightly) better. This is the kind of toy I mean
Drill Bench Press Stand Repair Tool Workbench Pillar Pedestal Clamp for Drilling | eBay Thanks for sparing the time to humour me! 🙂

Hi Everyone ,

It's been a while since I posted anything on here. I came across an old-school Alpine 3505 2-channel amp and need to replace one of the amplifier chips (Yes, it's a chip-amp). The 3505 has BTL outputs and is rated at 2 x 16W. Still has Alpine's ubiquitous 8-pin DIN inputs. Its big brother was the 3510, essentially a 4-channel version of the 3505.

Alas, I digress... I don't need the wiring diagram- I need to get the internal schematic, and most importantly, the part# for the amp chip. I know that the NTE1389 is a replacement chip, but I'd like to get the original chip number.

Does anyone here have any info or a technical service manual they can post a pic of? Thank You.

-Steve

Hi Guys


Just a quick one can anyone direct me as to where I will be able to get this transistor below. I was also wondering if I could use a PZTA92 in its place. Can some one please confirm this with me.

Thank you

why is obtaining missing parts an issue with the store?

my 3rd ACA kit was missing 2x 2.21Kohm resistors.

sent email to Elena telling her this.

she sends me a note to double check my box and let her know. i did, and sent back a note saying i still need them. crickets!

followed up few days later. still crickets!

i have a completed amp minus the 2x resistors, this is ridiculous. is there a phone number to talk to a human?

I don't use outputcaps in my Twisted pear setup, that's fine but i've got a "thump"sound when switching on the DAC.The (Ventus) LME49600 has a short circuit protection. I want to short the output with a relay for about 5 seconds before enabling the output. I don't want to put the relay in the signalpath. Can i do that without damaging the LME, or is it saver to put a resistor in serie with it. If yes, what would be the value ? Would 1kOhm be enough ?

Thanks in advance!

I have a couple of MerlinB's Compact Phono pcbs stuffed.
I have a Hammond aluminum chassis for the project, 15" L x 7" W x 3" H (38 cm x 19 cm x 7.5 cm)

I'll be using a couple of EI transformers I have on hand.

- For the plate supply (B+) I'll be using the power transformer from a Dyna PAS2 (660VCT 15mA).
- For the heaters I'll be using a separate Radio Shack 12.6VCT 1.2A transformer.

I saw this video which shows how to orient two EI core transformers for least induction.
Transformer Orientation - YouTube

From that, I came up with a basic layout (attached diagram and attached photo).

The idea is to:

1) Keep the audio pcb's as far away from the transformers as possible, and
2) Keep the transformers oriented for least stray field induction into the audio circuitry, and
3) Orient the transformers for least stray field induction into each other.

I don't want to make an external psu connected to an audio chassis by umbilical. I want to make the whole thing in one chassis.

Is this the best compromise to get least hum from this particular collection of parts?

Thanks for any advice.
--

I have a Nakamichi PA7 which goes immediately into protection, pulling well in excess of 1.75A. There is a "buzzing" sound (relays?) which accompanies this.




I have replaced the low value electrolytics on the PCBs, and have added (and now removed) the additional capacitance across c102/c202 which has been suggested.


The outputs all seem fine on multimeter testing, and I am wondering how I can "cold bias" the amp to try and test


any assistance appreciated


Peter

A similar thread is at Audiogon, but would be interesting to hear from DIY audio members too

The emphasis is to improve the outlook of passive attenuators, to be far more appealing to audiophiles, so that their overall position is lifted considerably, enabling as priority best audio performance, but also not sacrificing nice needed features

A few being able to zero volume and have as many inputs as needed, contact less with both input switching and attenuation to start the ball rolling.

It is time to replace belts on my 2 Nakamichi Cassette Decks and was looking for a reliable, quality source. I see them on eBay and 2 suppliers I see are WJOE Radio LLC and Vintage Electronics.net. Has anyone had any recent success getting good quality belt kits from any of these suppliers or have another suggestion. Thank you.

Hi, I have a 3 way system with one Seas Excel W26 ( 10" ) pr speaker.

Before I got my Accuphase F-20 crossing at 100Hz I was crossing at 200Hz.

Anyone have experience with his woofer in speaker system and what crossover frequency do you use / used?

Frank

Guide me please which supply rail is best for an amplifier.
70+70 vac 4 ampeer
Or
70 vac 10 ampeer

Hi,

I plan to use an RAC20-15DK to power aa X-Altra HPA-1 build in a relatively small case. Would it be fine to put a CLCLC filter on the output of it to filter out the switching noise? Something like this...



Mainly worried about instability of the AC/DC module as some of them can't handle much capacitance on the output.

What methods and techniques are there for protecting tubes and the output transformers in the case of a short or open circuit? I am building a tube amplifier using kt88's in a push-pull configuration. I would like the amplifier to have protection incase the amplifier is ran without a load or if a load shorts.

Thanks!

I'm not suggesting that this post become a sticky, but if the our resident experts share valuable information perhaps so. I'm in the middle of searching for replacement transistors for a Pioneer Amp - power transistors to be precise, but it could very well be any transistor in the amp at this point as they are all "obsolete"

Picking other components (caps, resistors, diodes, etc.) seems pretty straight forward, but transistors have quite a few parameters.

I see lots of posts from people asking "I have this [insert nomenclature] but I can't find originals any more, what do I replace it with?" No surprise, I am in the same boat - especially being a novice.

I've read a couple of articles on the interwebs that give the basics like,
Make sure Vceo/Vcbo is = or > than original
Make sure hFE is in the same range (O/Y/P or other designater)
Make sure Ft is equivalent,
and
Make sure Ic Max is = or >
oh, and form factor!

Sounds reasonable to me, but here is the question...
When is close, close enough, and when is close not close enough?



For example:
I started looking for 2SA1104-Y and it's compliment. They are obsolete - hens teeth now.

I found to be what seems a direct replacement: 2SA1694Y/2SC4467Y. They do not appear to be obsolete, but they are basically not in stock anywhere that I can tell or in any great quantity (perhaps covid related shortage?)

Other candidates in the same form factor are 2SA1909 and 2SA1695 (and complimentary)

When do the values of Vceo/Vcbo or Ic Max or some of the other parameters become too far away from the original?

And, what are some of the best sites that allow for searching on these parameters?

How to determine the cut-off frequency of lowpass filter? It appears on textbooks suggesting around 30-60 kHz, so does the google. But, what is the method or calculation to find the actual optimum cut-off frequency?

Hi
I just acquired Two Audio Concepts Subs (Model Sun 1?) and one of the Woofer units is MIA..
These are large subs which enclose a passive cross inside and a double coil / double magnet 12 inch woofer - each. they also have a small notch filter for the shelve speakers that accompany the set

They placed a car sub woofer unit to replace the orig one and obviously it performs differently..
Does anyone know who made these sub units for Audio Concepts or where can i buy one?
A used unit may be feasible too. if anyone have any / documentation on these units - please PM me
thanks much

Guys I'm trying to repair an amplifier that has the BC182C in the first stage of the amplifier.

I can only seem to get them for China. Is there a UK equivalent and if so which is better?

Any advice will be appreciate. Thanks!

Link to Album

Complete Cardmatic KS-15874-L2 Restoration - Album on Imgur

This was my Covid summer project of 2020 I did a complete restoration on a Hickok Cardmatic KS-15874-L2. The work took me about 2 months. I ended up having to replace every resistor and capacitor.


I own a couple of tube amps and I was looking for an affordable way of testing my tubes rather then going by ear. I had a heater failure with some Gold Lion 300B that took out a few parts of the the B+ circuit in my TU-8600R.


I found this Hickok Cardmatic KS-15874-L2 on ebay for about $300. The restoration itself cost about $250 in parts roughly.


The Cardmatic arrived with about 98% of its orginal electriconic components, meaning it was only ever worked on just a few times within its 60 years plus of its life, even the power supply tube are all orginal with the Hickok name on the glass. The last owner told me it was last worked on around the 90's to bypass some bad power supply caps.


I ended up doing a complete restoration rather than a recap when I found that almost every resistor was far off spec in the power supply circuit when trying to correct the messy capacitor repairs made in the 90s.


Hickok used carbon composition resistors almost everywhere except for where it mattered like the test circuits. They used wire wound resistors there. Anyways carbon composition resistors are made by adding impurities that increase resistance, these addives have different thermal coefficient, and so when they heat up and expand and contract over time they will crack and increase in resistance, they are also very touchy to humidity and will begin to short out, the micro cracks don't help. The worst offenders were 60% out of spec both over and under the labled rating. I went with mostly automotive resistors due to their fire resistance. All tolerances exceeded. So this tester is on point in the power supply now.


Every capacitor was far off too, I refurbished the cannister caps that I could.


There was only one bad potentiometer which is used for the screen adjust in the power supply. Fortunately the rest are in point.


I also had to recalibrate the card reader since it wasn't functional. It was a huge pain in the ***. I cleaned every pin off and greased with conducive graphite grease. The reader has to have the perfect clearance both when the card cradle is up and down.. too high and not all the pins will engage when a card is inserted. Too low and you risk shorting out the test circuits and the pins wont disengage when the cradle is raised, it took a week of a lot of trial and error and very very small adjustments. I'm sure Hickok has some special fixture for this in the factory.


I calibrated and tested every circuit and component using a set of 90 plus cards meant for this. And it is dialed in perfectly!! Everything was double checked with a Fluke meter.


I now have a nice tester to check my tubes in my TU-8600R and my TU-8500 pre amp!

Very happy I could get this little piece of electronics history fully operational!

It's been a while since I checked power dissipation, but my LTspice is not letting me selct power diss on active components. Diodes do show pwr diss. Opamps, transistors and tubes do not let me see power diss.
Any functions I may have disabled? thnx

That would be interesting, no? That would pretty much complete the DIY component line - amp, pre-amp, and DAC.

I’m going to attempt a design with the Satori TW29DN-B tweeter in an active system (miniDSP), and I want to implement a series capacitor as protection in the event that there is a power surge or breaker trip event that sends unfiltered signal to the driver. I’m going to go with the camp that recommends a value at fs + 200 Hz as the target corner frequency. My question is in regard to calculating the correct capacitor value. Do I want to go with the nominal impedance of the driver, or do I want to target the impedance at the cross point?

Thanks in advance.

I plan to use a hot wire cutter to cut XPS foam to make speaker horn moulds.
Wire size about 0.5 mm, needs ~5 amps.
A 1 metre cutter in nichrome is ~5 to 6 ohms - so ~25 V and 125 watts.
That is easy and reasonably safe with a transformer.
In fact I even made a hot wire cutter similar to this as a one-off project for a friend's factory to cut broadloom plastic cloth.
It was decades back so I don't even remember the power requirements but commercial units are similar to what I calculate so I don't think I'm too far out.
The idea for the new project is an improved circuit that controls the power to reduce idle losses and allow closer tolerances.
It should be not too hard to monitor both the current and volts thru the wire and calculate the resistance, to use in a feedback loop to keep the temperature constant.
Anyone seen a circuit to do this?
The obvious way is a simple micro-controller but maybe a simple all analog circuit would work.
Or other ideas?

David

Since the beginning of the Circlophone project, I had always toyed with the idea of making an ultimate test of flexibility and versatility: create a vintage, full-germanium version.


I finally had the time and opportunity to build one.

• It is an interesting test: would a modern topology like the C have been viable in the early sixties?

At the time, amplifiers were prone to thermal runaway and had to include a whole range of counter-measures like NTC resistors, compensating diodes and emitter resistors.

• An adjustment-free, totally safe amplifier would have been a considerable improvement, but is it actually possible?

The answer is here, it is the "Steamclophone", an amplifier built using exclusively components and techniques available in the early sixties.

Some adaptations had to be made, for mainly two reasons: one is obvious, it is the different material bandgap, the other being the slowness of Ge transistors compared to Si: they are litterally orders of magnitude slower.

This required some redesign of the compensations too.

Another problem is the lack of good NPN transistors: this mandated the use of P-darlingtons for the OP, instead of CFP's.
The bias currents also had to be corrected, because of the low allowable dissipation in the VAS and driver transistors.

The result however is still very much a true Circlophone, completely self-adjusting and thermally safe.
It worked almost immediately, with the quiescent current establishing itself at 190mA, just like its silicon brothers.

Now that I have the thing working, I will measure its characteristics and post some oscillograms....

Have fun!

Quest for the perfect amp! Ordered TPA3255 from Dr mordor 🙂

First of all, thank you for the answers to my beginner questions in a previous thread!



It helped me decide to go for Dr mordor's amplifier TPA3255 which i'm awaiting in anticipation.


Now i'm researching on where to go from there! Hope some of you can help me with this 🙂



So i have an Akurate DS as my DAC/Streamer. This has inbuilt digital volume control, and XLR outputs that i'm going to feed dr mordors amp with.


However, if i want more inputs on this amplifier i presume i have to add an input selector board in the back. And maybe a volume control pot. How do i wire these things up?


And can i buy some of the already premade boards on ebay without messing up the sound quality? 🙂


Would love to add bluetooth as well, but i know this can bring its own problems!

Thanks guys!

I just obtained a PE 3046 turntable that I would like to repair (ca 1974-1978). The PE 3046 turntable features automatic playing, however, I can only get manual playing mode to work. I have obtained the German PE 3046 manual (which I can't read unfortunately) as well as the manual for the similar Dual 1226.



The problem is this: there is a cam in the turntable that activates a black lever (number 155 in the attached photo from the service manual) which both raises and lowers the tone arm, as well as pushes on another lever down and sideways, using friction to move the tonearm horizontally to move it from the tonearm rest to the edge of the record (number 201). Whatever surface treatment was used to provide this friction has worn away and therefore the black lever simply slips when pushing on the lever sideways and the tonearm does not move horizontally automatically.


If I disconnect the return spring, I can get it so that I can manually place the tonearm and play a record, however, I would like this feature to work. What can be done to restore the friction? It feels like some gritty material was used to provide it. I tried to place a piece of rubber between the two but it doesn't work, it seems to require a lot of force.


If anyone has experience repairing such friction mechanisms please let me know.