....

hi
can i use 2sa1708 and 2sc4488 instead 2n5401 and bc547 in this circuit?and use 2sa1708 instead bc557
voltage of psu is +/-45 volts

This amp was designed by Ian Hegglun, according to his
'Square Law' rules, as described in his articles:
IansArticles - Google Drive
and
AUDIO_EW-WW_Hegglun_Square-Law-Rules_Sep-1995_errata.pdf - Google Drive

My attempt was to use hexfets as output devices.
It sims very well, at least at 1kHz: 0.000381% THD (I guess due
to the use of the opamp at the input),
and seems to be relatively simple to build.
I think I'll try TL071 as an opamp.
Spice sim file + lib with models attached in zip file.

Will try to build 1-pair output, with rails at 35V,
60W output, which seems reasonable for a single pair.

Any input and suggestions are welcome.
Ian, anything changed since you published your articles?
It's been over 20 years..

Hello All....
I recently acquired a Dual 721 in generally great condition.
There is a problem with the spring housing(58). When I first received the turntable it was nigh impossible to move the knurled wheel to adjust the tracking force. It seems to be clamped tightly in place by bearing screw(60). If I back of the bearing adjustment very slightly to the point where the spring housing is able to be moved, the action of rotating the knurled wheel also rotates the bearing screw(60) and further loosens the bearings.
I disassembled, removed and replaced the spring housing and washer, making sure the helical spring engaged the frame. No improvement.
I almost always use a digital gauge and adjust tracking force via the counterweight on my turntables, so operationally it is no big deal, but I would like to fix it. Any ideas?
Thanks
Stay safe
Peter

Any idea why?

well, hi again
i agree that this topic is old but still i wish to know the behaviour of lm1036 tone control circuit ,first intial 10 % rise in volume control is almost zero ,means their is no gain ,is this the charectaristic of the tone ic ??,or some thing can be done ,anybody who would help

I have SMPS from conex electronics (48V) for about 2 years that I use to power an amp (TPA3255). The combo was rock solid for all this time. I believe its a regulated PSU.

Recently got a new amp board that I'm testing, while hooking up and testing everything, the main power output is reading 69.4v without load! and now I think the amp is dead is this right or do I have a bad PSU? Aux power supply which 12v is reading 11.8v so close, but the main which is suppose to be 48v is puzzling!

Can anyone please explain this to me?

Just bought these Eltax tower speakers brand new in the box.(Old Stock) But no sound from the subwoofer.Anyone know about these Eltax speakers with built in powered subwoofers?

I have a pair of Event 20/20 BAS V3's and one of them developed a noise about 1 year after purchase (2014) which sounded like a noisey pot being rotated really slowly (low freq rumble/scratchy kinda noise). The noise would go away if you moved the bass potentiometer. The noise would then come back intermittently, sometimes right away and sometimes you wouldn't hear it for weeks.

Took the speakers back to the shop but they couldn't hear it. (It was pretty quiet and they were trying to listen in a noisey shop so not surprised) After i got them back it stopped happening so I left it at that.

Fast forward to now and the noise has come back, this time it's much louder and it won't go away with moving the pot so I assume the pot needs replaced. Event have discontinued the speakers and perhaps went bust? Anyway I'm going to replace the bass pot and might as well do the treble while I'm there.

I have attached some images of the circuit board where the pots are mounted, they are the blue pots, black one is for volume.

Lychee

Does anyone have a schematic for these speakers?
Has anyone else repaired these speakers and knows of a good quality drop in replacement or the pots?

For Sale: John Coltrane “Fearless Leader” 6 disk box set issued by Prestige


This is another box set I bought while in college and listened to it straight through one time. It has been stowed safely in a plastic tote for a few years. My job has me traveling throughout the US South and East and sometimes to foreign lands. I just don’t listen to it and I need to move again (for my job) and I am cleaning house.


The set is in “as new” condition and includes the book articulating the time and era these recording occurred. I don’t think I ever even thumbed through the book.



$50.00 shipped in the US. Paypal works best. Thanks.


Review here: John Coltrane: John Coltrane: Fearless Leader album review @ All About Jazz

Hi All


I have a meter from china who does very good, but unfortanely the display was damaged and I can not find one who fit, special the connections.

maybe someone here has a idea what kind of display this is.

Thanks.

First of all, happy new year everyone! 🎄🎉

Not too long ago I became interested in current drive amplifiers (I'm not suggesting to discuss pros and cons here!) and also I was looking for a hobby project, so for the sake of curiosity I decided to design a low power current drive headphone amplifier. Normally I don't do electronic design, therefore it took some time to come up with a circuit that satisfies my wishes. It still is a virtual thing and I'd appreciate any feedback from you guys on whether it's a sensible design.

Some goals and restrictions are:

• the amp should drive my ATH-M50X headphones well (which is easy with their 38 Ω flat impedance characteristic and high efficiency of 99 dB SPL at 1 mW [or sensitivity of about 113 dB at 1 V RMS])
• THD under 0.01% or -80 dB
• can use SMT components, but only with pitch of at least 1.27 mm

Please find attached the schematic circuit I came up with, as well as the LTspice project archive.

The two frequency response graphs are for C4 absent and present (input / voltage gain stage bandwidth limiting). Phase near 20 kHz is better without it and its efficiency is doubtful with the gain of 3 or even 1.5 (depending on whether R3A or R3B is used, which are for 1 V RMS sources and 2 V RMS sources correspondingly). I guess, I'll keep a place for it on a PCB (which is not designed yet), but won't put the capacitor initially.

The output impedance graph shows a quite even line at over 145 kΩ over the whole frequency range. I guess, this is very high for an audio amplifier.

THD at full power with 38 Ω load (28 mW) is under 0.02%, which is higher than the goal of 0.01%, but it goes much lower at lower power and there is enough headroom for ATH-M50X (which require only 12.5 mW to reach 110 dB SPL).

A few words about the design.

The input / voltage gain stage is as typical as possible, no comments.

The output stage is the defining part of the amplifier. It consists of two improved Wilson current mirrors (with emitter degeneration resistors) forming a bidirectional current source, which is driven by a class AB bidirectional current sink (with diode biasing) built around U2 and Q1.1–Q2.2. All the transistors are matched pairs of the same type, and U1–U2 can be a single OPA1642 (or with some range checks and adjustments OPA1656 or virtually anything else).

The improved Wilson current mirror has the least distortion of all BJT current mirrors I tried, but the emitter degeneration resistors are still preferred as they lower it even further. The booster after U2 is built in class AB to minimize distortion comparing to a class B booster or a whole op amp powered by the current mirrors.

Are you interested and/or have questions? What do you think about such an amplifier?

2020-01-02 update

Perhaps, it makes sense to clarify the limits of the "low power". The design demonstrates reasonable distortion level (less than 0.05%) at maximum power (remember, it declines with output power / volume) providing up to about 40 mA (with Rref = 100 Ω) into up to about 70 Ω load (lower impedance load will stress the output stage less, so the distortion will be less).

Hi all.

I have a defective Hitachy li-on charger, dead, a 1 meg resistor was open and came from the high voltage to the switch circuit, there is an ic with 6 pins 3 on each side one where the resistor was is short circuit. ic looks like a zener array or so.

It is very small, need 25 x magnity to see what is on it.

I can read 72 =pin1,6
50 =pin2,5
94 =pin3,4
from up to down, do not now pin 1 so can be also reversed but look a readable tekst this way.

measuring it looks like diodes, because some smps have a startup resistor and a zener I think about this. or does er excist smps controllers with 6 pins?

picture is example not the charger, asking hitachi for help does not work, this company is quite environment unfriendly as most japanese producers are.

regards

to all engineers,
as a audio enthusiast i am eager to know that if i have to make a choice between conventional class ab and double differential symmetrical input amplifer design ,which shall i prefer for domestic purpose and why ?

Hi all,

As part of my home theater build, have decided to go for 3 way actives for front LCR… so, need to build 9 power amps for fronts and 8 amps for surrounds… to pair up with my Sherbourn PT-7020A pre/pro.

I needed something as easy, but more powerful. This is when I and my friend John found the datasheet of TDA7293. This IC can run up to 100V, low distortion, and can easily be paralleled. Having built single chip amp and extensive listening TDA7293 is my favorites for IC power amp applications.

I have been looking for a source of PCBs using parallel TDA7293s… there are not many out there that you can buy. We then decided to do our own PCB. Our schematic is almost the same as in datasheet... the board layouts in the datasheet are flawed and little clumsy… we used them only as guidance with component arrangement on our PCB after few futile attempts to route the board with minimum jumper count.

Pin out on TDA7293 is tricky, so single-sided board is difficult to draw, and in the end contains more jumpers between lines than tracks… so, this one is made as double sided.

I thought it would be good to share my project with the community… maybe someone finds it useful.

Tentative double side PCB layout, top and bottom sides… have to check pitch and spacing with actual components we have before fabricating the PCB.



Between each revision, John will suggest this and suggest that, to improve the schematic and layout. Revised and final:

Hi, I'm building an F6 amplifier and soon I will build a Jeff Bagby's speaker, the Helios.

DIY Loudspeaker Project Pad Public Group | Facebook

Explaining the choices made for the crossover Jeff said "Regarding the impedance, the minimum measured impedance is at 4.5 ohm at 114 Hz, and the impedance runs above this over the rest of the spectrum. Most manufacturers would still call this an 8 ohm speaker. You may call it whatever you wish, because that single designation means very little. The tweeter’s crossover is very capacitive in nature due the very high roll-off. As a result, it should be noted that the maximum phase angle occurs at 9.7 kHz at 12.5 ohms and -63 degrees. At 20 kHz it is 6.5 ohms and still has a capacitive phase angle of -54 degrees"

The question is , F6 will have difficulties to drive this capacitive load?

Maybe in the future i will build another Firstwatt amp for passive biamp, is there another amp that will drive better the tweeter crossover?

Thank's to all, Luca

Does the Hifonics 1700.1d use the tl494 and the lm311? I can't tell the manufacturer scratches off the ic's like they have something to hide, lol

I am attempting to modify a Dyna PAS 3 in the spirit of Spice and the art of preamplifier design, Part 2
However, I am using mosfets instead of tubes in the out put stages. Based on advice and some simulation work, two ZVN0545As should work as drop in replacements for each 12xa7 being used as a cathode follower.

If this is correct, shouldn't I be able to use the stock PAS power supply? There are no new heaters, and the idle current in the fets would total an additional 4mA on the HV side.

Dear forum members,



I'm quite happy with my Cooler Master MH751 gaming headset, which is in fact a Takstar Pro 82 without the bass openings and with added microphone. I like its nonagressive but still noticable slightly V character and the overall sound without the need for any EQ whatsoever.



I built a small tube amp for it, which can perform even better if used with higher impedance headphones (this one is actually at around 28 Ohms, amp is 32-600 nominal, output power increasing as impedance increases).



Can you recommend me a higher impedance HP comparable to the Takstar Pro 82 in sonic character and comfort ? (I have medium-big ears and the CM MH751 is absolutely a favourite regarding comfort and isolation).



Thank you.

Hi!

I have a follow-up question to the discussion of how to effectively clean a board after soldering the parts:

Are trimpots sensitive to isopropyl alcohol / demineralized water?

I know that it is somewhat risky to be impatient after the board was rinsed (water-residues under caps etc.) but I'm not sure about wether a trimpot could take damage of it?
(On my last build, I have finished my board except the trimpots, cleaned them and only then soldered the trimpots, just to be sure...)

Are other parts, like relays etc. at risk?
thanks
david

Hi guys. This is my first post but I have enjoyed the exchange of ideas and creativity here for some time. I recently purchased an enormous number of NOS tubes from an estate sale and I need help testing them. I am more than happy to compensate you for your time in cash, tubes or what ever you're comfortable with. I would prefer to do them in batches starting with some valuable ones to recoup my costs from the purchase. If anyone can test volt and trace curve that would be wonderful. There are 100's most in the original boxes and I may have something you're looking for. PM me or respond to the thread and I will get back to you shortly. Thanks in advance.....Kyle

I have a BMS driver with steel threads screwing into a plastic horn with brass threads. Do I need any teflon tape or thread dope on this screw in connection?
Thanks

I have received several requests for a circuit board for a sweep tube based amplifier. Most of these center around my 6LU8 Spud, but the board for that amplifier would need significant rework to be in shape for professional fabrication. So I decided to take new look at the various options for a sweep tube Spud. The 6LU8 is a nice tube. It’s has a triode and a power pentode in one bottle. In addition to the 12-pin Compactron version, it’s available in a 9-pin Novar version labeled 6LR8. This tube is an excellent candidate for a Spud amp.

Another Novar triode-pentode combo tube is the 6KY8. The 6KY8 and 6LR8 share the same pinout. The 6GF7A is a Novar tube with a small signal triode and a power triode in one bottle. The pinout of this tube is the same as for the 6LR8 and 6KY8 – except for the screen grid pin - which, in the 6GF7A, is simply left floating. Convenient that…

After much research, experimentation, and optimization, I have come up with a design that supports all three tubes. With some creative wiring, one could use a 6LU8 as well. Note, however, that the 6GF7A runs best at a lower B+, so rolling all three tubes through is not an option without changes to the power supply. I ended up using 250 V B+ with the 6GF7A and 300 V with the 6KY8 and 6LR8.
With the 6LR8, I get about 6 W in UL mode and 4 W in triode. The 6GF7A provides about 2 W (sounds really sweet too!).

The total parts budget (including the cost of the PCB) starts at just shy of $200 (not including enclosure and shipping charges).

So without further ado, I bring to you the Novar Spud.

~Tom

What are you folks talking about in this forum? 😀 I need some serious help to get some traction to begin to understand, and even ask sensible questions.

Could some gentle folks here point me to threads or articles that explain these things in noob terms? I searched diyAudio but have not found suitable introductory material. Or is there a book where I could learn about digital music play-back and how to put systems together? Something like a “Digital Music Systems for Dummies” book, that would show me what all the hardware and software parts are and how to put them together into a system that would play music over my stereo system.

I am a long-time tube amp and loudspeaker builder and like to listen to music. Recently I’ve been considering converting my records, CDs, and tapes to digital format to enable better management and accessibility. Somehow I missed the boat on this topic, and now I don’t know where to begin. I read these threads here, but they make little sense to me - way over my head.

Thanks.

Francois

I'm building a power supply very similar to the one seen below for my monster Class A amplifier. My question is, what is the accepted practice or calculation for choosing a bypass cap value? I've seen all the way from .1uF to 10uF.

Regards,
Dan

I have this pcb that I got off ebay for a few bucks.
I'm building a preamp and I need a -15/+15v supply for it.
The schematic they included in the listing has slightly different resistor values compared to the ones on the pcb because it is for a fixed output. This is actually how I plan on implementing it. The board also allows for an adjustable output using trimpots.

Only thing that has me scratching my head is the LF353 opamp. What is the function of this? Does it keep the outputs equally symmetric?
Can I safely leave this out of the design? Or is it recommended I leave it in?

What can I say, built something I like better.
$500.00 plus shipping conus

I'm rebuilding the input board of a Stasis 3 (the 125 wpc version of the Stasis 2).

The schematic shows two 6571 NPN transistors with their collectors attached to the emitters of two A42 NPN transistors. From what I've read, some call this a 'double Darlington pair' and to avoid DC offset, matching the hFE is a good practice.

I found the A42 at Mouser. But the 6571 was out of stock. The NTE website says NTE123AP is a cross-reference equivalent.

I bought extras of both. I found two A42 that are roughly the same hFE (95-105) but the newer NTE123AP are much higher (173-190).

Question: Do the A42 transistors need to match the hFE of the NTE123AP?

I have 100 2SK170BL I would like to trade for 100 2SJ74BL. Let me know what you have. These are genuine Toshiba on tape purchased from well know DIY audio member.

Thanks

Hello,
It's been about 6 month I told myself I should join you.
I am quite new in the diy world I think I might stay for a while.
I have ordered a pair of hammond 1609 and my first project will be a 6p15 pp 🙂 (I still hesitate about the preamp and phase split stage, I wanna go solid to save the planet (yeah, I know)).


I might need your help now and then, I have some few technical questions I couldn't find answer online.

I am a CS guy and know some things in embeded application and signal theory.



Regards,
Simon

I'm having problems with the input selector. I seems like all the inputs are active at the same time, so the signals get mixed and distorted.

Does anyone know if it's a common problem in these models? What should I check out first?
Does anyone have a schematic for this amplifier?

One of the truly great classical guitarists.

I've encountered an issue on my bench where something is creating intermittent interference at exactly 20kHz and 25kHz, strong enough to be picked up by a high-gain input stage, even with a 68k grid stopper right at the terminal. My first thought was some nearby SMPS, but the only SMPS devices on my bench are a Fluke 45 and a Hantek DSO4072 - the rest are all linear. I'm about 10 feet away from a 5kW solar inverter, but I'm still seeing the interference when that's quiescent. There's also a transmitter for an invisible fence system, but unplugging that doesn't affect it. So I'm stumped.

Besides, aren't 20kHz/25kHz awfully low frequencies for SMPS? What kind of device might be behind this?

I hadn't looked at Class-D for a couple of decades and I was surprised at the performance levels now being achieved. This prompted me to have a go at building my own. After much reading I decided on the TPA3255 with post filter feedback in stereo BTL configuration.

The power supply is a 400W 48V LED supply out of china turned down to 45V. I chose this one because it has a thermostatically controlled fan which doesn't kick in at normal listening levels. The minimal heatsink gets warm to the touch at ear shattering levels from my Klipsch floor standers.

I'm still looking for a suitable enclosure but in the meantime I've breadboarded it on some acrylic.

The inputs are balanced but my DAC isn't so I'm using balanced to unbalanced cables.

The chokes I wound myself using 15 turns of 2 x 1mm stands on sendust cores. with AL=51nH/T. These barely get warm.

I'm still waiting on some 48V to 15V DC-DC modules so in the mean time I've fitted a 7815 with a couple of 100R/1W droppers.

How does it sound? Well I don't have golden ears but it's on par with a tube hybrid that I have except that the bass seems tighter and it has a very neutral and uncoloured sound. Despite the single power supply, imaging is also very good. And it is so quiet.

Gerbers for the PCB are available if anybody wants them. How did I load this board? rather crudely! I apply solder to all the SMT pads using my iron and then dip each component in rework flux before reflowing them into place using a hot air tool.

hi everyone,
i need to add a passive volume pots for my aleph 30 in balanced way.
i am planning to use 10k 24step ladder attenuator pots like this one :



my question is:
how to wire this attenuator for dual channel balanced
using only one attenuator like in the picture.

thanks.
visit my blog here

Hi All,

Most should know what this stuff from the Sony TC500/TC500a R2R is. I picked one up to cannibalize the power supply.

The surrounds on the Coral FE103A variants feel pretty good--not too stiff. See minor damage to one dustcap. I don't think that'll make a difference. These are nicer than my personal set, but I'm too lazy to swap them out.

The Tamradio/Tamura-ish transformers look fine too. These used 6AQ5 outputs and are great for EL84 or 6V6 SE projects like the RH84. Interesting possibilities with the recording head tap.

$75 for the speakers, $50 for the OPTs. $15 to ship to CONUS for either the speakers or OPTS. Free shipping to CONUS if you want it all. Others ask for quotes.

Paul

I'm looking for an amplifier project with 18c51 tube.

Hi Folks,

i was wandering about (mostly) cheap pa coax drivers, that they have the same sd in their manuals and test as a driver would have without a small horn embedded in coil.
So if one for instance would take an emi beta 10 or 12 (and the 8 inch too) they have like these small horns inside their coil for the hf, but should this not be went in the calcultion of the overall sd for the driver as well...? Like ok a twelve inch speaker has an sd of roundabout 500 and whatever square cm...sorry folks i'am metric 😀, and you have to deduct like whatever the horn would be?

Ok one could assume that the dustcab would count into the overall area as well, but in the case of these drivers the dustcab is more like a stiff mosquito net which lets air flow through, so maybe not countable?

Would be glad if someone can elaborate this, and why most manufactors still put it the way they do?!

Greets Swany

Can someone here tell me how to change de emphasis on a Dyna FM3? Oddly, or not, I'm now not sure, the de emphasis on my Tandberg 3001A sounds like it would in the EU when set to 75uS. It's definitely overly bright so I switch it to 50uS. It now sounds great. OTOH, the Dyna FM3, which functions as it should, sounds like it needs higher de emphasis. Does anyone know what it actually is?
TIA

SOLD: MSB Multiple Volume Control MVC-1 (Qty 2)

SOLD: Qty 2 MSB Multiple Volume Control MVC-1. Passive 8-channel pre-amp with remote control. One master, one slave for a total of 16 channels. These are from the days I was using active cross-overs on all three front channels of my home theater. I had these between the DSP and amplifiers.

Sorry the slave cannot be converted to a stand-alone unit without a new microchip which I don't have. Perhaps you could clone off of the master chip or contact MSB. Otherwise the two units are linked together with a network cable. Very high quality case and internal components.

Asking $350 OBO for the pair plus shipping and 3% paypal fee. Local pickup possible. I will not separate.

Hey everyone!
So I was looking around for some cool tubes and this baby caught my attention.
The seller doesn't know much about the tube and stuff and he has provided only 2 images. He says in the description that it's off a military thingy and it works on the HV side.
Just by looking at the pics, I can see the letters "ТМИ-9" which is basically "TMI-9". I can't really see the other number(s) and was wondering if people who are into Russian tubes know anything about this.

Obviously, searching for "TМИ-92", "ТМИ-90" or "ТИИ-98" doesn't yield any results.

The images have been attached below.

I am looking for opinions regarding the SB Acoustics MR16P 6 inch midrange driver and the ScanSpeak 18M-4631T 6.5 inch midrange driver.

I am looking for both subjective evaluations and objective comparisons (beyond what can be obviously determined be examinin the spec sheets...)

I intend to use these drivers from 200 Hz to 1.6 kHz in an active 3 way.

The SS 18M is about $220 while the SB MR16 is about $150. I want to understand if the SS 18M offers performance which would have value in my application.

I've designed a board to evaluate the Lm3886 and Lm2876's in stock and I need your opinion on how it looks.

I broke the PCB out of its cheap plastic case today, and was wondering why there's a capacitor between the + and - of each channel.

Any ideas?

Thanks!

Aurum Cantus APR 3.0’s
Excellent condition!
Rarely used
They were $600 new

$250 for the pair seems quite fair 🙂

For those of implementing a multi-way active XO with EQ APO and Peace, how are you mapping the Peace channels/speakers to your DAC channels?


There's a "select a device for the equalizer" pull down menu in Peace where I can select one of the four stereo outputs of my DAC but I can only choose one for all the channels. If I select another output, change to another channel, the output for that channel has also changed.


I'm using (or trying to) use a Presonus VSL1818 as my 2X8 processor. Is it the audio interface driver that is the issue or ?

Is there a specification for the 8 x M3 holes in 10mm front panel for 5U Deluxe chassis?
If a drawing exists that can be printed and used as template for drilling exact holes in a mounting plate that would be helpful. A quick look into DiyAudio Store only revealed the specification for the holes in the heatsinks?

There is something i find rather confusing, and that the delay x-over orders create. I always hear that using a 1st order will result in no phase change. However 4th order will end up with a 360 degree phase change. 3rd is 270 degree change and 2nd order 180 degrees. This leads me to believe that first order actually has a 90 degree phase change but because it's one low-pass and one high pass, they cancel each others time differences and therefore is phase coherent. This is probably true for a 2 way, but what about a 3 way were the midrange is using 1st order on both the high- and low-pass side? Also, does that mean that if using the same order of low- and high-pass the lead and delay will cancel eachother? And is this delay just phase related or time delayed as well? Because if so, as long as you have the crossover point low enough, the difference in orders between low and high pass can make the drivers time coherent even when the acoustic centres have different distances to the ear.

Don't know if I'm talking rubbish, but if you know, or know about any good source material I'd appreciate it

Would anyone help me with some design rules to apply a baxandall tone stack in the feedback loop of a headphones amp with a gain of 10...20x?Both inverted and noinverted popology would be considered.

This amp has me stumped. When I apply power and remote. Nothing happens. Also it appears to have 2 tl594 chips which is something I've never seen before.

Using op amps, in the usual inverting configuration and the non inverting configuration.
What is important to achieve a best gain stability.
I am thinking of:
The resistors with low temperature coefficient.
Thermal matching of resistors.
What else, should I care ?

The gain value does not need high accuracy, there will be calibration to take care of this aspect.
The important thing is the need for a perfectly stable value.

Ok...I'm old enough to remember techs using Rubylith film to layout circuit boards.
Anyone else?
Wikpedia Rubylith if you don't know what I'm talking about.
If you look at solid state gear from the 60s through the 70s you'll notice the PCB traces are of variable width, and most evident, are not necessarily orthogonal. Often the junction of three or more components will be implemented with a large fill area they all emanate from. Corners are round or any shape you can dream of.
Laying out with Rubylith required developing skills with a razor knife. It's nothing you could do successfully right out of the gate. You'd have to waist some material before you got good at it, and the material was not cheap. Sometimes a special table that guided a razor knife or parallel razor knives was used. I never did it personally but i witnessed guys doing it who are likely 70 years or older by now.
Anyway, I have a Peavey guitar amp, the Session 400, from 1975 that I still use frequently to this day because I've never found anything that beats it sonic-ally. The layout was obviously done with Rubylith. It's totally discrete, The pre-amp is single supply using many coupling caps between stages etc. I have simulated the circuit and have concluded there are some interesting design twists you don't find in other circuits, like a "loudness" affect and an interesting and effective parametric mid control. The power section is 200 watts! - done with all NPN.
I wonder now if the trace routing style makes any impact on the sonic qualities.
Anyone with an opinion on that?
Also, is there a modern software package that can do this style?
I imagine the graphic arts people have something but likely not optimized for layout. - probably lacks net/schematic coordination.

I recently heard a passage of piano where you could hear the mechanical elements of the piano as the musician played.....pedals being pressed and the hammers actuating ...can't remember what it was but it was a good genre of music to 'show off ones system...it sounded really good.

Any links or heads up of anything that sounds similar.?

I am not a speaker designer or engineer, just a curious designer who's been obsessed with horns for some time.

I've always been amazed there aren't many options when it comes to horn speakers - especially conical horn speakers. The only ones I can find from the likes of OMA or Avantgarde are tens of thousands of dollars.

I want to build something based around a JBL 2446 in a conical horn and a faital pro 12 or 15 woofer. I mocked up a really rough design of a speaker design I've struggled to find from an aesthetic point of view that I find pleasing. Of course this could be created in many different finishes.



Any takers? 🙂

(This is of course just for fun)

Hello everyone
It’s the first time am posting in this forum, in this project I’ve tried to push the amp to the extreme without losing stability, with the help of the books of Mr. Douglas Self and Mr. Bob Cordell I think I’ve achieved an amp with a Phase Margin of 110° and a Slew Rate of about 120V/us, with a very simple 3 stage amp. Till now it’s just simulation, am using Multisim, and the results looks very promising.
Any suggestions is very welcome, hope to find you all in good health and stay safe
Best regards KADER

For an MM phono preamp, is a SINAD of over 100dB even theoretically possible using modern state of the art OP amps and circuitry?

Ok how can I use 1400 uf 350 VDC computer grade electrolytic capacitor(s) in a tube amp power supply. The company my son works for installs server farms and they have a case of NOS never used 1400 uf 350 VDC computer power supply capacitors heading for the dumpster. I told him to grab it for me. I was thinking as part of a brute force power supply for a preamp or amp running on under 300 volts. They are Sprague capacitors so not Chinese crap.

For sale a pair of F6 modules built on boards supplied by palstanturhin.

Well matched genuine Toshiba jfets supplied by spencer with matched mosfets from ha. The boards can also be altered to run with a diamond buffer front end instead of the jfets.
https://www.diyaudio.com/forums/pas...forums/pass-labs/216616-f6-amplifier-609.html. See post 6084.

I would like £150 for these to include UK postage; elsewhere at cost.

Hi good people! I want to install Tang Band W3-871SC in my car on top of the dashboard. The enclosure therefore cant be too big, so I wonder if attaching a tube to the enclosure will work for raising the volume. In my case I would hide the tube in the dashboard. At home such a tube could be hidden behind furniture. For example if closed box I would maybe make an enclosure with 0,5 liter enclosure and to this attach a tube with 1 liter internal volume. Would this equal an ordinary 1,5 litre kabinet?

Cheers!

Hi guys, I’m looking for some horns for a 2nd room. Which is better ?

Guys,

i have an issue and not quite sure what is causing it, but lets see if somebody has come across it.

Working with no issues using CSR8645 bluetooth amplifier board. Noticed that youtube has tried to mute the sound a little on a few songs so please disregard the poor sound.

Designs by 3rutu5 - DIY Boozetooth Speaker MK3 - YouTube

I've currently tried boards from various sources and get the same issue on all but one board.

CSR8645 (have 3 of them, one works flawlessly in above video)
CSR8645 Bluetooth V4.0 Amplifier Board Module APTX 2*5W for DIY Bluetooth Sound Box

and

CSR8645 (have 2 of them)
Bluetooth 4.0 CSR8645 Amplifier Board 5W+5W APT X Stereo Receiver Amp Module| | - AliExpress

QCC3003 Bluetooth Audio Receiver Module
QCC3003 Bluetooth Audio Receiver Module 5W+5W Power Amplifier Stereo Support Call BLE5.0

and

SANWU-HF69B-6W+6W (only have one)

SANWU(R) HF69B 6W+6W Dual Channel Stereo bluetooth Speaker Amplifier Board Power - US$7.46

I've been wanting to run a low powered bluetooth speaker setup just using a solidarity 18650 batter and a single speaker. All builds were based on AUKITS bose clone where a step up module was used to go from 3.7v to 5-6.5v which all boards can handle, and all but the SANWU were to have a 2000uf capacitor across the VGC, GND connection onto the board. The problem i'm encountering on all 4 boards is once the volume goes past 3 quarters volume or something with a bit of bass, the unit restarts and sometimes cannot reconnect. I dont know if the problem is specific to using these boards as the green one in the video does not experience this.

My thoughts is potentially it is due to the supply potentially, but as i removed the step up module for a test and changed it over with the DC\DC isolator i'm not quite sure. As it restarts, it could be under load and have a protection circuit or something on board, but i just dont know. The SANWU i havent had any luck with, but have seen a guy add some extra capacitors to the board, but i dont think it was for the same issue.

below somebody else's experience with the board.
https://www.instructables.com/id/DESIGN-AND-BUILD-YOUR-OWN-PORTABLE-BLUETOOTH-SPEAK/

I do realise i'm using no name chinese gear and it could come down to quality control or just the person i based it on could have got it from somebody else and have a slightly different board, but any advice for this noob would be greatly appreciated.

If i can finish my last project using one of these 4 boards successfully with an addition of a capacitor or something would be awesome.

Hi !

Anybody know what's the best class D IC model for hi-fi sound quality ?

Is it possible for an audiophile to go into class D without pain?

because I try only one time to compare LM3886 high quality parts amplifier VS TDA7498 and it was simply horrible !!! 🙁


thanks in advance 🙂

nicK

Hi,

I was asked by a friend why his Madisound BK-20 pair (fitted with TB W8-1808s instead of the Fostex) sounded so different from his previous speakers. Being a scientific fella, he wanted to know if the "different" was "better"... and despite the can of worms, I took a listen.

They sound bad. Off. Displeasing.

So much so that after an ad-hoc test of frequency response, I decided it was a great opportunity to play with the near-field scanner (that I never get to use...) since it is one of the few modules that can be used with a full system. (n.b. I've measured the drive in question free-field before and know it's, QC issues aside, not at fault)

I'm probably not supposed to post the actual graphs and measurements, so my 2-cent synopsis is that the response is very direction sensitive, a few degrees this way or that and the frequency response is all over the place. It's not just beaming, the problem is well down to 400Hz or less, and the best part is that it doesn't just scale with amplitude, it just morphs and changes in a wondrously non-linear way.

So I felt somewhat vindicated, but then wondered if there was anything to be done. I will admit I don't have a lot of back-loaded horn experience.

Is it simple or intractable or somewhere in between? (It did occur to me that swapping out 1808 for 1772 might help?)

Hey,


Could someone recommend tested board and verified seller for Chinese AK4493 DAC board.



Thanks in advance!

Evening All

I have recently closed on a new house that we will be moving into in the next week or so. I have been fortunate enough to have been designated an "office" space so I can move from the current dining room table setup into something a bit more suited for productivity. The challenge is that the room will also double as a "guest room" and triple as my "music room".

I have been looking at the space over the past couple of weeks and have some ideas but wanted to do some gut checking with the community before starting anything as the concept is a bit quirky.

I have a pair of mono-block SET amps based on the 2A3 which are good for about 6.5 amps per side, which I really enjoy and plan to use in the new room.

The room itself is 150" wide and 180" deep. There are a couple of extra alcoves (entryway, bathroom entrance) that increase the space slightly but I am ignoring those for now. The ceiling is 106" at the walls with a raised center.

The basic idea is to install a Murphy bed along the short (150") wall. Alongside the Murphy bed will be some built in cabinets to provide bedside table functionality and extra storage. Outside of that I plan to build some speakers, filling the space to the walls. The Murphy bed assembly is 90" tall.

I initially looked at doing a BIB or other large TL (even toyed with folding the TL over the top of the Murphy bed towards the center of the room, but it all got a bit complex). My major concern with the BIB approach was given how far apart the speakers are (around 135") and how close the drivers would be to the exterior walls, that I would not get a good result at my planned seating position, about 84" from the built in assembly.

Instead I decided to look at a full height sealed box with a large FR driver (thinking AN or Fane). Based on my estimations I could build a box with exterior dimensions of 14.25" wide by 16" deep by 90" tall. Only problem is that wouldn't fit a 15" driver and would still have the wide separation concern. So I considered whether I could angle the front baffle toward the center of the room.

The attached drawing shows speakers with the front baffle angled 30 degrees toward the listener. That makes the front baffle 16.5" wide which should be about enough to get a 15" driver on. In the drawing the black square is my estimate of my seating position beside my work desk (shown in green). The triangles coming out of the speakers show a 10 degree dispersion (in red) and a 30 degree dispersion (in yellow).

Without accounting for internal bracing or driver volume I calculated the internal box volume at about 350 liter (12.5 cubic ft). So good volume to handle even something like the AN Classic 15 Alnico.

But I have not seen anything online with similar geometry (narrow, tall sealed box) and with an angled front baffle, which leads me to believe there is probably a major reason why not.

If anyone has any ideas as to whether this will be a complete disaster, or has a good suggestion as to something else I could do with the space please let me know. Or if anyone has good experience with a BIB stuffed into a corner with a relatively close listening position please let me know. I am totally open to trying something different with this space, and while my diy skills are not the best I think I could have a go at most things. But I honestly have struggled to find much in the way of design ideas for a fully built in solution.

Thanks, Phil

Hello,

I am looking for the Encore DL2010a preamp's owners manual & schematics.

Encore was a Kansas City company founded by two Honeywell aerospace engineers in the late 1980's, Garic Laughlin and Michael Fessler. There were many prototype versions of the DL2010, all were state of the art at the time. This version was the best and last version that Daric Laughlin produced.

Best regards,

I have an SE D3a driver setup that seems to work pretty well in simulation. I need to swing the grid of the D3a to within .2 volts of 0 to clip the output tube though. Anybody have experience running them like that? Are grid current problems likely?

The basic setup is resistor loaded cathode biased 180V A-K @ 18mA with the heater biased up to +50

Thanks,
Marty

Hey Y'all how are you doing? Im only new on here and i have minimal knowledge on electronics but i have some knowledge. So ive just got a kriesler model 11-102 and it is a beautiful machine. I knew when i got it it had minimal sound out of the right speaker. Anyway first thing i did was test it and the sound from the right side is minimal on both the T/T and the radio. I went and replaced the cartridge and stylus on the Garrard 60mark2. still the sound is minimal. The left side has full sound. The volume seems to work okay as the left goes loud as and the right does go louder but no where near what it should be doing. so any thoughts? it may just be something simple. ive checked speaker wiring loom, all valves are nice and orange. speaker transformers arent hot. what do you guys reckon?

With a full range, we are forced to sacrifice to some extent on both ends. OK. My question is for smaller drivers, FE85, RS100 etc, where we are pushing our luck to get down in frequency. To achieve a subjective overall balance, how much hump before LF roll-off do folks prefer, and how much early roll-off on the top? How much does it vary as you do push lower?

I ask as I have seen diligent efforts and done so myself to get 80 to 15K or so quite flat, but they sounded like crap as desktops. Measured several micro-speakers, ( Warfdale, RS, and no-name) All had quite high Q alignment and early roll-off even though they all had tweeters.

They were used in JVC speakers packaged with their executive stereo systems. Are the drivers available separately?

Thanks to all, as always.

Hi all
Trying to adjust the antiskating force of my “SME 3009 II Improved” to suit the needs of my SHURE M97xE which is equipped with a brush damper, a few theoretical questions arose. Surfing around for answers three articles caught my attention:
1) B.B. BAUER: “Tracking Angle” (ELECTRONICS March 1945) [http://www.helices.org/auDio/turnTable/bauer.pdf]
2) J.K. STEVENSON: “Pickup Arm Design” (WIRELESS WORLD May-June 1966) [http://www.helices.org/auDio/turnTable/stevenson.pdf]
3) JOHN WRIGHT: “Bias Correction and Dynamic Conditions” , HI-FI NEWS October 1969
[archived at 09 March 2004 at www.Vinylengine.com]

In 1) Mr. Bauer provides the means to calculate the skating force across the arm’s travel, provided coefficient of stylus friction "mu" is known (he estimates a value of 1/3).
In 2) Mr. Stevenson estimates the lateral thrust (i.e. skating force) as 20% of downward pressure.
In 3) Mr. Wright explaining the results of his experiments, he comes to some conclusions, which seem to contradict Mr. Bauer theoretical calculations, like ” Bias force is therefore substantially unaffected by the surface speed” and “Bias force is therefore substantially unaffected by the playing radius”. The reason of the discrepancy is that these results (as also Fig. 5 and Fig. 6 of Mr. Wright article) are based on experiments conducted on unmodulated record grooves. At the end of his article Mr. Wright deals with modulated grooves and their effect on skating force. He concludes that “Bias force is therefore substantially directly proportional to modulation velocity-at least for sinewaves” . His Fig. 7 provides experimental data for friction coefficient ”mu” .
Combining formula from 1), and ”mu” data from 2) the attached drawing was produced. The 6 thin curves represent the skating torque produced when an elliptical 0.0003x0.0008in stylus hanged on a radial arm with the geometrical data of an “SME 3009 II Improved” is reading a record with grooves modulated with signal of varying modulation levels (0dB refers to 1cm/sec at 2 kHz).
Two things become easily evident:
a. The skating torque variation due to modulation variation is 30%.
b. The curves follow the form of the well-known tracking error curve.
Both smell trouble.
Practical antiskating mechanisms do not adapt automatically to increased skating torque due to varying groove modulation.
Practical antiskating mechanisms do not provide an antiskating torque, which follows such a curve.
(Continues)
George

Just wondering if there is a proper way to terminate the output so to test output level with 1 volt P-P input. I'd like to compare my Aikido's for output level

Bought Jamo 507 Speakers last week. Beautiful cabinets. Cones all good. Unable to test. One speaker has very low volume. Switched out speakers with other. And still low volume. Switched channel on amp. Switch wires later. Tried All the combos but still low volume no life. no obvious signs on crossover. It’s almost like open wires are crossed someplace. can't get To the woofers buried deep in the cabinets. Sure would appreciate any clues.
And by the way the good speaker sounds amazing. Wow. I think it’s called the Denmark sound.
Connected second set of speakers to amp to confirm both channels work as should.
Thanks folks

I'm running out of space in my lab and need to clean it out so I'm selling a few things I no longer need or haven't used in a while. Open to reasonable offers.

AP SYS2722 (see my separate ad) $9500

Shipping is not included on the following items:

Audio Precision AUX-0025 Switching Amplifier Measurement filter including $95 rack mount kit: $900

AP Rack mount kits -RAK-212 for AUX-0025, etc. and slide mounts for the 2722. I bought a box of these and it contained more than I needed, most are brand new: $35/set for new, $25/set for used

Eico 666 Tube tester (solid state) works, clean for it's age but has a flakey test switch, manuals included: $150

Datron 1062 6-1/2 digit multimeter not working (EEPROMS probably need to be reflashed), display lights up, beryllium copper binding posts. $40

I'll post pictures and more items later

Hello,

When looking at Alps Alpine RK271 series potentiometers for volume control of line in on a LM3886 chip power amp, what difference does 10K, 20K, 50K or 100K make?

Anyone know where to find a 10K version right now?

Mouser is sold out right now, Parts Express sucks shipping to Canada and I am trying to avoid a counterfeit one off Ebay.

Thank you,

David.

I was excited to find this little gem for under $500 initial testing looks good, so far....


8808A

I thought that speakers setup in a circular array like the Tekton Double Impact and Impact Monitor were not a good idea. Are they able to get away with it because they are tweeters?

I'd like to know whether this kind of configuration could work well with full range drivers and what benefits it would have (beyond just efficiency)? Any potential drawbacks like comb-filtering and what does that sound like?


Impact-Monitor - TektonDesign LLC

Hello, I've finished making Chiomenti's "Lo scherzo" whit ECL82 tubes and I must say that it plays OK, even though I don't have very efficient speakers. However, I noticed that in one channel, precisely that relating to the O.T. on the right (see diagram), it was initially buzzing. The problem is that at first I was running the 8Ohm output through the wire just behind the power transformer.
Now, I ran it around the case like the diagram. The buzz has decisely decreased but it is always slightly higher than the other channel. Moreover I have the perception that it is a little bit louder (tried with listening in headphones because I did not feel it with the speakers).
Any suggestion for this?

Forthermore, since I wish to use it also like an headphone amp because low wattage, what kind of adapter could I think of for proper running? Thanks.

Hi all!

I wonder if people might be able to give their advice on this, please:

Hopefully I am moving soon and the place has just been rewired (UK NICS cert.) and I need to build a rack for my system that has to run from either one or two (depending on suggestions) mains sockets.

Gear:

Computer
USB Sound Card
MiniDSP 8x8
Parasound Zamp Amplifiers x 2 (mids and tweeters)
Behringer NU1000 (stereo sealed subs)

Furman M10X Power Distribution

The caveats are:

- Computer and MiniDSP must be on at all times
- The rest of the system including TV/monitor must be powered on by the Furman power unit.
- Ideally should be run from one power socket if possible


I don't jam dat volume too hard but watch do movies with dynamics. I can't imagine I draw that much current for the whole shebang.

Attached is a schematic (and blank) of the system. Apologies for the fruity-tooty colour scheme.

What do you lot think? This is basically how it is now and I get bad noise from the USB soundcard but I think that's another issue to do with the cheap PSU in the computer and/or unavoidable system noise from ground loops.

If you have time to have a look and make a suggestion it would be most appreciated.

Cheers!