Hello - my name is Nik. I'm from Denmark - and to be very specific, the small island Funen in the middle of this tiny kingdom (until recent a tiny queendom).

I'm absolutely new to this stuff and hope for some help.
I saw a thread here about a rebuild of a NAD C370 which inspired me to take my NAD apart, to do a rebuild of my own - with some help (I hope 🙂).

Well that must be it for now...
Nik

While checking the output transistors in my 565 (in circuit) I measured 0.018 ohms when checking emitter to base, not .05 .06 volts. All the outputs I checked ,even on the working amp tested this way. Does this mean that they are shorted?. I have not been able to go further until this question is answered. Yes, this is the first transistor amp I've tested. Please help. Thanks, Kevin

Some were upset by my last Repair / Rebuild.
So all I will say is this.
They sounded like rubbish before.
No treble, and one side had almost no mid-range.
I investigated, found many issues, and it was decided to do a full rebuild.
These are factory original. Matching serial numbers. Never touched before now.
Did you notice one side using different parts ? From the factory.
After the rebuild using far superior parts, everything is now working as it should.
Plus some.

To head off all the old worn out arguments.
A lot of the capacitors are in parallel banks. The capacitance of each bank was matched to the original.
The old inductors were measured, and the new inductors were selected for correct inductance AND dcr.

If the owner wishes to comment further (they are a member here) then that is up to them.

Hello,
I'm facing an annoying issue with my DAC. I use the Denafrips Hermes as a DDC, connected to my PC via USB, and outputting AES/EBU to my DAC. The problem arises when playing files above 96 kHz or switching off my PC ; the DAC produces an irritating ticking sound that seems to come from a relay ( RY2 as shown in the attached schematic) .
Are there any modifications that can be implemented to avoid this ticking sound?
or
can i just jumper RY2's Pin 7 to 8 and 4 to 3 and remove the relay from the digital section ?
thanks

Would it be possible to 'erase' a magnetic multi-pole strip / sheet to 'record' a short piece of low fidelity music on it (using an electromagnetic head etc.) ? The resulting 'tape' is then expected to be 'played back' using a hall-effect sensor, much like a music box. Kindly note that this cannot use a standard cassette system for legal reasons.

What would be the feasibility of the above and any issues (magnetic or other) that one might face while doing so ?

Thanks.

I’ve been playing with an equalizer. I discovered that my speaker system sounded better when I boosted 3dB at the woofers’ operating range. Since my speakers have 2 woofers per cabinet, I realize that one way to achieve 3dB gain at woofers’ operating range is to adding the third woofer to each cabinet. However, I also realize that paralleling 2 woofers together will obtain 6dB gain on woofers’ operating range. So what is the benefit of adding the third woofer to the existing two woofers connected in parallel? Should the 3rd woofer be connected in parallel or series, assume all drivers are identical?

Guys,
i know you both have your webpages excel workbook on Brian's , and freecad scripts on Lords
i want to tweak this design for different drivers
is the Staiper mini scooper MS-18 MK2 and MK3
source page here
MS-18 MKIII

Hi ! i have this british amp with output devices mounted of the metal case that works as heathsink ... very british way

in a word it looks quite messy
In a car audio amp i have seen this much more elegant solution with a thermal conductive sheet and a bar to keep the devices attached on the surface


This solution among other things will allow for a easier removal of the entire board
I have spotted some bad solderings but i would like to work out of the case
Any suggestion ? Thanks a lot
gino

hi all,

Long time reader and first time poster ! Currently building my second 834 Clone and greatly appreciate the threads here and elsewhere on the subject.

Alan
West Midlands, UK

Hi all,

TLDR; I've got a tube amp from an old hifi I'm hoping to convert into a guitar amp and am hoping for some circuit analysis help/advice.

A while back I picked up a pair of Symphonic 1260 stereo consoles which came with mono tube amps (schematic below). I gutted the consoles and refinished them and they are now lovely living room accessories with all new electronics. So NOW I've got a pair of at-least-partially-functional (one works but hums after a while, the other one seemed to be badly need all the pots cleaned and maybe other stuff).

(this isn't mine, but this is the same amp I'm working with if you want a pic: https://reverb.com/item/12970609-symphonic-model-1260-vintage-1957-6l6-tube-amp-works-great)

I'm hoping to recondition these and build them into a matched pair of guitar amps for a friend and I (and by "guitar" I mean "cigar box electric ukulele", it's a companion project to the amps). I'm not a pro musician, these will probably never be used to perform, I don't care if they sound amazing or not, but it'd be a delight if they didn't sound like garbage. I'm not currently an electric guitar player and have never owned a guitar amp, so a lot of the details I've read about are lost on me.

My general plan:

1. Switch in a solid state rectifier
2. Replace all the filter caps. Probably add a bigger one right after the rectifier.
3. Clean all the pots real well and attempt to verify that things are basically working. Replace tubes or other components if necessary.
4. Excise/disconnect the existing tone controls (got that schematic from here: http://www.rru.com/~meo/Guitar/Amps/PA2Guitar/index.html, will pick values later but probably just go with one of the two listed there)

Questions:

1. Does my proposed new schematic (i.e. removing and replacing the tone control) make sense? Is that generally where I want to be hooking things up?
2. Do I need to fiddle with the preamp circuit at all (the first 1/2 of the 12ax7)? I also have no problem adding a different/additional preamp to this if it needs it (something like https://till.com/articles/GuitarPreamp/)
3. Volume pots: should I add more?
   1. The linked article suggests one after tone control (circled in blue), and perhaps a dual pot on the inputs to the push/pull tubes - does it make sense to add both?
   2. If you were going to add in another volume control, where would you put it and why?
   3. What are reasonable values for these (500k? 1M? log taper I assume?)
4. Am I completely off base and crazy?

I realize I could probably just get these running and sell em off to buy some amps, but they have some sentimental value and I'm pretty interested in them just for the fun project value.

I have a question about this link from G to link on F5 Turbo front end board: Can the f5 turbo board take balanced input at this point (i.e. the link is to ground the negative input and push the amp into single ended mode) or am I misunderstanding this configuration.

Dave Slagle (Intact Audio) is building for my Audionote Kit DAC 4.1 a couple of permalloy-core I/V transformers to replace the original ones from ANK.
I will add more details and my listening impressions once I have them in my hands and I have a chance to try them.

Having a clearout pending move to EU land. Standard audio grade transformer I previously used in a Pass FW amp before converting to dual transformers.
Tried to get a reference price from Toroidy and looks like they don't do online sales to the UK. Cost of item plus post to Ireland is £80 on the website (400 Polish Zloty)
Weight inc packaging 4.5kg

For sale to UK only tracked with signature £58 Paypal Friends and family or BT

Collection in Shrewsbury £50 Cash

Will consider reasonable offers.
Bit dusty - noticed after taking pics but excellent condition.

I am visiting Malvern Sat 22nd June and maybe the Cranage North west audio show on the Sunday so some scope for a meet up/delivery.

I'm selling a pair of Focal Audiom 11 WX drivers, which are used but in perfect condition. I no longer have the original packaging, but I can assure you they will be packed securely. If needed, I can provide photos of the packaging process for your approval. You can find the technical specifications in the following link: Datasheet

The price is fixed at €1000 for the pair, payable via bank transfer. Shipping costs will be the responsibility of the buyer. I'm not interested in any material exchanges. Please feel free to reach out privately if you're interested.

I'm selling a pair of Focal Audiom 15 WX drivers, which are used but in perfect condition. I no longer have the original packaging, but I can assure you they will be packed securely. If needed, I can provide photos of the packaging process for your approval. You can find the technical specifications in the following link:Datasheet

The price is fixed at €1500 for the pair, payable via bank transfer. Shipping costs will be the responsibility of the buyer. I'm not interested in any material exchanges. Please feel free to reach out privately if you're interested.

I am looking for recommendations to complete my new system. I need a Dac new or used under $1500. Preamp is a used vac cla-1 mk3, amp is vtv purifi stero amp, speakers are EFE t22 mtm design.
The inputs seem to be xlr or rca for the dac. I mainly listen to streaming music out of convenience (amazon) but open to there formats. I like blues, classical, jazz. Rock. Just anything that sounds good.

I'm starting a new thread to focus and clarify the problem(s) with the CDM-1 in this Magnavox FD2040.

Symptoms: Random difficulty reading certain tracks on different discs. Sometimes it's near the beginning of the disc, sometimes further in, and other times near the end. It will skip and/or act like the Search button is being pressed, i.e. playing in a speeded-up fashion. After a moment or two of this, the laser will go back to the beginning of the track in question and try to play it again. The other symptom is that either the spindle motor or radial drive motor (hard to tell which) is very noisy. The nature of the noise is pretty much what's described in this thread.

Now after several weeks of observation, the only variable I've found that affects the symptoms is leaving the unit powered on. If I leave it powered on (not playing, just idle) for an hour or two, it has no problem playing discs that were previously an issue. In addition, the motor noise is completely gone. So my first assumption would be a failing transistor or bad solder joint on either one of the laser boards or the larger servo board, which I can try to pinpoint with hot air and freeze spray. If anyone with more familiarity with the CDM-1 has a sense of where to narrow my search, please chime in.

I need your kind help with one challenge I have. I call it a challenge as I am in disdain and not experienced with BJT-circuits design.

Topic: I would like to use one-BJT (not two or more) for providing a single audio Line Out from many sources Inputs of various output impedance (some are low, some are high) via a switch. Practically it should be a buffer with much larger input impedance than any of the inputs, I softly guess.
Now, comes the hard part of the request:

• SNR: > 100dB
• THD @ 0dB: < 80dB for even, and <90dB for odd ones
• headroom: 14dB (amplitude 5V)

Of course, I could use the switch alone, but the sources are not properly buffered and I am afraid not to mess them up.
The input signal amplitudes are scaled to 1.0V (0dBuRMS)
I have a +18V PS, regulated.
The one-BJT can be NPN or PNP, whichever. I can care less about this.

The first attempt I made it ended lousy: I used a BC547 with CC topology. The output signal has 2-nd harmonic (-40dB) already present even at low amplitudes. At around 0.5V amplitude it started to show huge distortions, both even and odd. Examination show that the positive side are softly compressed, enough to get now ALL harmonics at around -40dB.

Attached the CC-topology I used. The simulations did not show these distortions.
The measured DC voltage on emitter is indeed 8.5V as simulated.

Any hints? What I did wrong?
Is it at all possible to fulfill the above requirements with only one BJT?
Which topology and schematic/components would be better (still one-BJT topic frame)?

P.S. I saw too late that my title is a bit off. This is not a mixer, rather a line buffer. Sorry.

Capacitors for sale : Mundorf, Audio Note, Clarity Cap, Jantzen Audio
Shipping extra.

NEW :

Jantzen Audio Superior Z-cap:
0.1uf 1200VDZ x2 $13
0.47uf 800VDC x2 $16
0.22uf 1200vDC x2 $14

Clarity Cap CSA:
0.1uf 630VDC x2 $19
0.47uf 630VDC x2 $19

Mundorf MCap EVO Aluminium Oil
4.7uf 450VDC x2 $26
3.9uf 450VDC x2 $24
0.33uf 450VDC x2 $21

USED (some may have solder marks on plastic wrap):

SOLD - Audio Note Copper foil Mylar in oil
0.1uf 630V x2 $85

Jantzen Audio Superior Z-cap
2.2uf 800VDC x2 $24
0.33uf 1200VDC x4 $31

Jantzen Audio Silver Z-cap
0.47uf 800VDC x2 $26

Clarity Cap CSA
4.7uf 250VDC x2 $20
3uf 250VDC x2 $19

Mundorf Supreme silver gold oil
SOLD - 0.22uf 800VAC 1200VDC x2 $71
0.22uf 690VAC 1000VDC x2 $71

Multicap RTX
0.1uf 600V x4 $50

Clarity Cap TC600 film power filter cap
175uf 600VDC x1 $40

Hello All!

So I was able to score the driver and woofer mentioned above from a friend (2 of each). My question is two fold.

1. Will these two work well together?
2. If they do work together what’s a good crossover schematic for these? My enclosure would be something similar to a Devore O/96.

I’m also open to any other ideas you all might have. Thank you in advance for the help!

Hi All,
i need to inject 48vdc into a channel strip and it needs to come from a 18-0-18 ac transformer. I will only need to power one mic. Ill be building my own so i need a schematic....any suggestions. The mic ill be using says 8ma minimum draw.
Thx

Hi Folks

I'm inspired to save these Panasonic drivers salvaged from an old Olevia tv and have fun building a set of desktop speakers. This is my first build, so I read the pinned threads on this forum and searched for 2.5-way enclosure plans online before writing here.

Panasonic Driver specs/info:
25-watt each set, so 50-watt total all 6 drivers
Tweeter: 2"; 6 ohm; model EAS6PH132A - G7N203
Coaxial: 4"; 4 ohm; model EAS10P646A - G7N206
Woofer: 4"; 4 ohm; model EAS10PL636B - G7N206
Tweeter has a capacitor.
Mid & Woofer are in phase.

How to determine dimensions for a decently functional sealed enclosure or even an open baffle with the available specs above? I'm assuming ported is more difficult given the lack of info. Perhaps this is where art pulls ahead of science. The original design had the tweeter and coaxial firing forward with the woofer firing rear and ported.

I found this guide as a general approach, is this sufficient? SteveHoffman.tv Forum

Also, I have this amp: Pyle PCA2 Compact Bluetooth Amp

I'll update with any progress as this goes.

Thanks!

Pics:

Hello everyone,

I am starting to use a Rigol 1052E (I have not used a scope for 30 years or so, so am going up the learning curve).

It all sort of makes sense with the exception of measurement values if I take a Power supply (AC at 15V) with a 10x set probe it measures 4.28V P to P

On all the measurements I attempt it seems to be 3.5 times lower than expected.

I have run the self calibration software and it made no difference, any ideas?

Thanks, Rich

A quick inquiry to Mr. Thatcher has me intrigued. I noticed Randy experimenting with different
methods of grounding. One was the typical CL-60 bypassed by a cap and the other used a bridge
rectifier as a 'grounding' device. A quick search revealed a post about the bridge rectifier method as far
back as 2007. See post #8 below.

What means ground lift?

And he was kind enough to send me the following link.

Ground Loops

Does anyone have any further info my brief use of the search engine has yet to uncover?

Regards,
Dan

Hi, new here. I would like to build my first OB and I maybe got carried away and purchased all of the components for the Monacor Katana. However could some kind soul give me the dimensions of the baffle and the sides/bottom with the correct angle to match the original design? Does the baffle need to be acoustically 'dead' or can it be any material of the correct size. Was wondering whether one of the new composite finished cement render board/laminated, (ply-like) boards would work? Thanks, Brian

Gain structure (AKA Gain Staging) is a concept that gets talked about a lot in pro audio, but most home audio folks have never heard of it. Understanding gain structure can help you get the cleanest signal possible out of your system and avoid some nasty things. Things like noise and clipping, which might sound cool from a guitar amp, but not from a Hi-Fi system!

What's gain? Basically it's amplification of the signal. When we increase the voltage level of the signal, that's gain. Current gain can also be important, but we'll mostly be talking about voltage gain here. The "structure" part of gain structure is the various voltage levels throughout your audio system and the gain it takes to get them to those levels.

How is gain expressed? Typically either in amplification factor (times or X) or in decibels (dB). So if one volt goes into an amp and two volts come out, that's a gain of 2X, or 6dB. The dB is a logarithmic function as opposed to a linear one and is often seen on VU meters and other audio scales. Take a look at this month's column by Jan Didden for more about decibels.

What is the overall gain of a typical home audio system? Let's start with an extreme example and assume that you're a vinyl lover using a moving magnet cartridge. Your speakers are inefficient and need a lot of power so you have a 300 watt power amp. How much overall voltage gain do you need to get that tiny signal coming out of the phono cartridge up to the 300 watts (50 volts) coming out of your Ear Buster amp? A lot! A gain somewhere in the neighborhood of 13000X or 82dB, sometimes more. Imagine a microscope with that kind of magnification, and all the little specks and dirtballs you might see clouding the image. Similarly, imagine all the noise your system might pick up along the way with so much gain. If you have a moving coil cartridge, its even worse!

SET amplifier fans can gloat, as they might have an overall gain of only 2000X. If they are running a CD player into a flea power amp, that might mean a gain of only 4X. But since flea power owners probably use more sensitive speakers, they can still run into noise and clipping problems.


Where does the structure part come in? It's about how much gain (or loss) each section of the system has. The phono preamp will have a lot just to recover that tiny signal from the cartridge. The preamp or line stage will add a bit more, and then the power amp will have gain also. Keeping the levels reasonable throughout the whole chain gives us good gain structure.

Adding up how much gain each section has gives us the overall gain of the system. Now look over at your preamp or integrated amp with that big knob in front that "goes to eleven". What you are looking at is gain's twin brother from an opposite universe, attenuation. All that volume knob does is attenuate the signal that comes before it by dividing the signal and reducing the voltage. Typically in the 12 O'clock position the volume control attenuates by 20dB, cutting the signal to 1/10th of what it was. But it has not changed the gain of each section, only divided the signal, (attenuated it) at a certain spot.

Now we know the two sides of the structure, gain and attenuation. Both are important. Most simple home audio systems have only one point along the signal path to control gain, the main volume control, which controls only by attenuation. The gain of each section does not change, you've just divided the signal at one point. So that extreme system with an overall gain of 13000X will still have an overall gain of 13000X, it's just that somewhere along the path you've used a voltage divider (your volume control) to attenuate the signal. And the sections downstream from the volume control will amplify everything just as they always did. But now they are amplifying a smaller signal, the signal you attenuated with the volume control.

So how about a practical example? Suppose some evening you're with that Special Lady. You've poured the wine, lit the candles, and now it's time for that famous Barry White CD. Mmmmm, mmm. Bring on the love, baby. Being the smart and smooth audio dude that you are, you know that Mr. W sounds his sexy best played at 2 watts average power on the speakers in your "Love Den." So what voltage levels, gains and attenuations will you need to bring out the best in Barry? Right now you don't care, But Hey! Snap back to reality and look at the sexy graph below.


Barry's voice is going to be recorded at about 16dB (average) below the maximum level possible on the CD. That is a standard mastering level. If your CD player or DAC is standard, then that's going to mean an average level of about 0.32 volts coming out of the RCA connectors on the back. That 0.32 volts will then be amplified 3X by your preamp and 30X by your power amp. But that's 29 volts out of the power amp – over 100 watts! Not going to set the mood, is it? No, Special Lady has run for the door!

That's why we have a volume control in there - to reduce the signal to a reasonable level. You can see that the system has too much gain for the evening's festivities, but that's OK, just turn it down. Now Barry is crooning, not shouting. Throw away some signal in the middle of the chain so that it doesn't get too loud at the end. In this case the volume control has divided the voltage level by 7, (0.14X) or -17dB. So tomorrow when you want to rock out with AC/DC for your victory lap, you can just turn it up and unleash the power. So far, so good.

But if we look back at the system, we see that for most situations, we have more gain than we need. Maybe 15 to 20dB (10X) more gain than we really need. And that can lead to noise. Why? Because any noise that occurs after the volume control does not get attenuated. In fact it gets amplified. You've cut down the signal from the CD player by 17dB, so now it's 17dB closer to the noise in every circuit that follows. Any noise from the preamp, the cables, bad connections, etc. will be also be amplified 30X by the power amp. You took a medium level signal of 320mV (0.32 volts) and divided it down to 44mV so its now much closer in level to all the noise living in the bottom of the system.

Too much gain or bad gain structure not only gets us into trouble with noise and clipping, it can be a pain for practical reasons, too. I remember a big old Pioneer integrated amp from the 80's, a massive, heavy thing. Big transformer, VU meters, clip lights, serious knobs and switches. Did maybe 75 honest watts into 8 Ohms. You could connect any standard source like CD, radio, tape, phono, and you barely had to crack the volume knob to get a big blast of music. "Wow, this thing's got power, you hardly have to turn it up at all!" But did it really have tons of power? No, it just had too much gain. The volume knob would not get past 9:00 before the amp was clipping, so the useful range of the volume control was from “Nothing” at 7:00 to “Clipping” at 9:00. That sure made adjusting the volume very touchy. Stupid design, far too much gain. Despite all the other good aspects of the amp, the primary user interface, the volume knob, was a pain in the backside.

Let's return to the signal path to see where things might be done better, or where they are often done wrong. Generally speaking we want to run amps and preamps at a fairly high level. That means that the signal (the music) will be at a much higher voltage than the noise so we have a higher signal to noise ratio, S/N. That's a good thing. But just how high a signal voltage do we need to run? Usually we want the peaks of the loudest signals to be about 3dB-6dB below the maximum that device can do without distorting for the best s/n ratio. That can be hard to determine unless you've designed, built or measured the amp. Power amplifiers might give you a clue in their specs, but preamps and phono stages usually don't. How much signal does it take at the input to drive the device into clipping? Knowing that will tell you where your gain should be all through the chain.


There aren't any set standards as to what the input signal should be for a preamp or power amp to reach its maximum level, but there are some conventions. Input levels that will drive a device to full output can range from 0.77 volts to 2 or 3 volts in the consumer market, and even higher in pro audio. So you may have a preamp that will hit maximum output when it gets a 0.7V input signal. That would be a problem with standard CD players, as they output a maximum of 2V, but the preamp has a volume control, the voltage divider we talked about before, that attenuates the incoming signal. This attenuator is often the very first thing in line after the input selector. Sometimes there will be a buffer circuit before the volume pot, but that is more common in pro gear than consumer equipment. Our 2 volt signal coming from the CD player may need to be attenuated before it ever hits the preamp circuits or it will overdrive them. A typical preamp will amplify the signal by 2 or 3X after it has passed the volume control. This is then passed on to the power amp.

The power amp is going to behave much like the preamp, it has a certain amount of gain (30X is typical) and it will take a certain voltage at the input to drive the amp to its maximum power. How much voltage? Again, we may not know. You might find it in the amp's specs, or you might know because you designed or measured it. Either way, at some input voltage level, the amp will reach full power. Here is where we often find a difference in consumer power amps and pro audio power amps. Pro amps have a level adjust on the inputs, high end consumer power amps often do not. They may not need it in simple systems, but if they don't have an input level control they will apply full gain to everything coming in. The result? You have to turn down the preamp volume to keep the power amp from getting too loud. Turning down the preamp will attenuate the signal near the beginning point of the preamp circuits, leaving any and all noise from the following circuits to be fully amplified by the power amp.

Because we have attenuated the music signal at the input of the preamp, it's now closer in voltage to the noise in the whole system downstream. We’ve destroyed our good S/N ratio.

A good digital source like a CD player, DAC or high quality sound card will have a signal to noise ratio of 90dB or better. But that ratio is the maximum signal over noise. Music isn't recorded at the maximum level, its average level may be down 16, 18 or 22dB below peak, at least on well mastered CD's. But the noise floor of the device doesn't change, so effectively there is a "Music to Noise" ratio of only 74dB or less. In other words, the noise coming out of your speakers will be 74dB below the average music level. That's still very good and most of us can live with that and never hear it, but there is trouble brewing...


Looking at the flow chart above, we see two systems. On top is our system with an overall gain of 90X. Below it is a system with a lower gain of 20X. Both start out with a musical signal of the same voltage -0.32 volts and both end with 2 watts at the speaker (4 volts). But along the signal path we see big differences in the signal voltage at corresponding points. The 90X gain system has to reduce the CD output by a large amount or it will be overdriving the power amp and speaker. The 20X system uses only moderate attenuation of the signal because the subsequent gain is much less.

Now imagine that we pick up 1mV of noise right after the volume control. In the 90X system, that will reduce the music to noise ratio to 33dB. Not great. In the 20X system 1mV of noise at the same spot would reduce the ratio to 46dB, a 13dB noise advantage for the low gain system.

Picking up 1mV of noise at a less sensitive spot like at the inputs of the power amp would result in a 42dB ratio for the 90X and 52dB for the 20X system, a 10dB difference. The above example is simplified for clarity. In reality noise would be picked up all along the signal path and be amplified to various degrees, but starting out with a higher signal voltage still helps at all points along the path.

Things can get worse. What if you use a piece of pro gear like the DCX2496 crossover? It's meant for the higher signal levels of the pro world. To drive it to maximum we need 7 volts RMS! It will take lower levels, of course, but remember that those lower input levels are much closer to the DCX noise floor. Our CD player won't drive it high enough with its 2V RMS maximum output. Our preamp might just get us close. It has a gain of 3, so with the volume wide open we'll get 6V into the DCX. That's enough to keep it happy and keep the signal up out of the noise, but then what happens? The pro crossover now outputs 6 volts as well. That level is so hot it's going to drive our precious power amps into severe clipping. Six volts into our power amp with a gain of 30 means 180 volts out of the speaker terminals. Not going to happen unless it's a 4 kilowatt amp! Again, too much gain. If the power amp reaches its maximum output with a 1V input, we have no choice but to turn down the preamp. So we turn down the preamp until its output is 132mV as seen in the 90X system. If the crossover has an optimistically good S/N ratio of 95 dB, that still means 0.2mVof noise added to the signal, so we are at an S/N ratio of only 56dB coming out of the crossover. What to do?


To fix this gain structure problem we put an attenuator on the inputs of the power amps to reduce that 6 volt signal to a usable level, or we build amps with low gain. Preferably both. Or we find a crossover that works in a range closer to the signals provided by the CD player and preamp.

Obviously the more complex the system gets, the more we need to worry about gain structure. Using a simple system with only a CD player and integrated amp, we can usually just spin the Barry White disc, set the volume, and get down to business. But with a more complex system Barry may get lost in a fog of noise before you do. That's going to spoil the evening.

© Panomaniac 2011

I built this LXMini last year when I was looking for a project and I’ve enjoyed them for what they are but I found a good local deal for some Forte IIs and they’ve displaced them for my listening. I painted them green and they’ve sustained some chipping but I’ll touch that up. The biggest issue with them is that there is a dent on one of the drivers. Asking for $425 with the MiniDSP with local pickup in Boston. I’d rather not ship as one piece because I have no idea how well this would fare but I can ship the drivers and wooden parts.

Can someone give me the schematic of this chip?
TD5168A

nice to join this group

hi there. I am looking into this forum to find help building some 2 way smaller speakers suppositely to go on a floor stand of some kind + a subwoofer also ..

Hi, new member here who has recently dived into the deep end of vintage keyboard repair and is getting up close and personal with old analog components. In doing some searches, ran across your group and found the discussions very helpful. Glad to be here!

Update May 31ST Price Cuts, Sold Items etc. *


Getting down to the last of it. Pretty aggressive price slashing- fraction of what you might find these items for elsewhere. Some things basically being given away.. Doesn't make much sense to go lower with shipping included. Grab what's left before it disappears.


Prices are all POST PAID IN THE USA. No International Shipping. If you must have something and are international, have it shipped to a US address and then to you.

Scroll through Photos as some are mixed.

** STILL AVAILABLE AS OF June 18th **

Sota John Curl MC Step up Head Amp - Classic battery powered MC Step up - Out of production, works last time I used it- for sale in the wild - $500 Price Cut: $450 Final Price Cut: $375 Photo

Carver M500t Magnetic Field Amplifier with hard to find Rack Handles - Recently Tested, working. Refitted with banana plugs. For Sale in the wild $500 Price Cut: $400 Final Price Cut: $300 Photos

Heathkit Condenser Checker - Partially Restored? Unknown - Looks Top Notch - For reforming caps, testing caps- $120 Price Cut: $80 Final Price Cut: $60 Photo

Chicago Filament Transformer - $85 Price Cut: $75 Final Price Cut: $50 Photo Photo

Boozehound JFET MC Step Up - with matched 2SK170 & PSU / power switch , Mil hand matched Polystyrene caps - $120 Price Cut: $75 Price Cut: $50 Final Price Cut: $45 Photo

LP Puck - $40 Price Cut: $30 Final Price Cut: $25 Photos

Audio Salon Preamp (with transformer)- $15 in USA Photo





******** SOLD ITEMS *******

Huge Component Lot - Note: There's been no cherry picking here and this was his personal stash and it's the best of everything. Dale RN series resistors, non-inductive wire wound resistors, Kiwame, etc. Resistors range from 1/4 - 5W, most being somewhere between 1/4 - 1W. Tons of large quantities of RN60 resistors. Film caps are Oil caps, teflon caps, polystyrene, mil spec, etc. as well as your usual wima and so on. Electrolytics are mostly of the top-notch series, Panasonic FM, etc. and Ceramic mostly COG/NP0. Mica also the quality Cornell Dublier etc. Like I said it's the cream of the crop, and it's all meticulously organized and labeled. Truly an amazing opportunity for basically a readymade DIY audio workstation. I've attempted to box this accurately, to maintain the organization- multiple boxes with dividers nested into a larger box. Again, this is 20 years of cream of the crop audio-specific parts collecting. —— SOLD ——— Photos Here

Component Grab Bag - This is all assorted stuff that I missed on the first pass or was in some other nook or cranny - tons of oil and polystyrene caps, all kinds of stuff. Who knows?! Find out. A completely packed USPS Large Flat Rate Box. $SOLD Photo

Dynaco ST-70 - Unknown Condition - Partially upgraded with various additions, manual included. With tubes vintage and JJ ——- SOLD —— Photo Photo Photo Photo
Large Electrolytic HV Cap Lot --- SOLD --- Photo

Large Film Cap Lot - ---SOLD --- Photo

RN 55/60 E Series + Mica - Organized and labeled precision values - —— SOLD ——- Photo

Trimmers, Diodes, and Misc. - —- SOLD——-

TMOQ Boards - These grew out of the Romy The Cat 834p thread (End of Life Phono Preamp), and then made it's way over to Lenco Heaven where many of us where pretty smitten with a certain tube phono preamp circuit. a whole ton of boards, some partially assembled, with two different power supplies. Probably 50 boards total or thereabouts - after I sell 50% of what's here, these will go for free (you pay shipping) to a trusted DiyAudio member to distribute amongst the community or sell for proceeds to diyAudio or whatever you so choose. Photos Unknown shipping cost? $40 should cover it in continental USA Photo Photo Photo Photo Going to Tronan for distribution

TMOQ 834p + Jessica PSU (See Lencoheaven 834p thread) - No Tubes - --SOLD-- Photo Photo

Lenco Speed Controllers - 2x PCB - $SOLD Photo

Guitar Amp PCBs - Tweed Bluezmeister and Tweed Overdrive Special - Partially assembled with premium components, some Carling switches and Axial Electrolytics - SOLD Photo

Frog PCB Guitar Pedal / Preamp Lot - SOLD Photo

Douk 834p Boards - $25 in USA - SOLD Photo

Jessica PSU + Potted and Shielded Transformer(See Lencoheaven 834p thread)- SOLD Photo Photo

Denon DL103R - Maybe an hour of use? -SOLD- Photos

Tube Books - Hard to find stuff, Allen Wright book, etc, ---SOLD --- Photos

Tubes - Make (Reasonable, please) Offers -----SOLD ---- Photos

Phono Preamp - End of Life Trademark of Quality 834P - This is one of two I completed for myself. I'll keep the other. I consider this, as did Romy the cat and many others an "end of life" phono preamp- no more searching required. This version is made with boards I had especially made, uses a 12AT7 in the cathode follower. Has all tubes (NOS RCA, Westinghouse, and Phillips 12at7 ), fully wired up - I don't have time to test this. Assume is fine, may need a cold solder joint attended to. Everything is ultra-premium. ---SOLD--- Photos

PCB - Baby Huey EL34 Boards 2 - A Brand new set of boards, rev. 2 - --SOLD-- Photo

2SK170 JFETS - 3 lab matched pairs - --SOLD--

Grab Bag #3 - Heatsinks, Connectors, Jacks, Tube Sockets, Potentiometers, Switches & Misc All High Quality - $100 Price Cut: $75 Photos

Test Jigs - Includes Pete Millet Soundcard Interface (Link) Very high quality reverse RIAA, and other goodies. Unknown status of the tube soundcard interface... I believe it needed the screen replaced (screen replacement is included). --SOLD-- - Photo

Dynaco Driver Board - --SOLD-- in USA Photo

His Master's Noise MC d3a Tube Preamp Boards - Stuart Yanniger design, almost fully assembled with premium components - diyaudio thread here - ---SOLD--- Photo Photo

Copland CSA-14 Receiver / Amplifier - This was working beautifully, and then there was a minor problem (leaky cap, I believe?). No serious damage, comes with manual. Seen sold for $1500 and thereabouts. Tube driver stage, solid state output. Really love this thing, surprised it hasn't been snatched up yet. Build quality on Copland is exceptional. --SOLD-- Photo Photo

PCB - USSA-5 - For some reason, 5 PCBs, with one set of parts, includes 2SK170BL matched and some other, now unobtanium, parts - diyaudio thread - diy audio thread 2 - sold —- Photos

Cartridge - ATLH15-OCC + Empire SE/X 1000 MM Cart - Broken Stylus - Replacement Here - imho the best moving magnet cartridge ever made, eclipses the Shure V15 series. Will include an errant Sony headshell and Pickering V15 in unknown condition - —Sold —- Photos

PCB - Baby Huey - EL-34 Bandol's Boards - diyaudio thread One set of boards almost fully assembled. One spare. With documentation. Two Chokes —Sold —- Photo Photo

Variac - General Radio W10MT3A 10A and 2A capability. Built like a tank. Extremely heavy, shipping will be high $450 in the wild - $350 Price Cut: $300 --SOLD-- Photos

Turntable - Luxman PD-441 Turntable - The ultimate turntable, according to some. armboard, no arm. altered drive mechanism - two hairline cracks at rear of dustcover - comes with Funk Acromat, Omega One anti-static mat and stroboscope disc - *Extremely Heavy - $100 Packing Surcharge $600 Shipped Price Cut: $500- --SOLD-- Photos

Preamplifier - AMB a10 - Fully populated, premium components. Includes a bunch of extras. Disassembled. Prob 2k in premium parts? **** SOLD Photos

Linear DC Power Supply - SOLD Photo

PCB - Tube PSU Lot - Stark Boards, 6.3V and HV 50-400V boards suitable for tube preamp, SET, etc. - Originally intended for use with John Broskie Aikido Boards / info here - Includes docs - Populated SOLD Photo

** Original Post ***

**********

Hello.

Longtime diyaudio member / enthusiast has fallen ill.

I'm assisting in clearing some needed room. Space is still enjoying the music, but the tinkering will have to come to an end. This is well over 20 years of collecting and tinkering. This is everything left from his immaculately organized home "workshop."

I've done my absolute best to accurately display and detail what's included. Everything has already been boxed. All prices are post paid in the United States when paid with PayPal friends and family. I have a lot of experience packing delicate items so don't worry on that front. No international shipping. If you are absolutely dead set on something, and live internationally please contact me.

Also, I cannot answer specific questions regarding "can you check that this specific item is in the lot?" and so on. Everything is already boxed and ready to go.

Nothing is sold with any indication it works perfectly or works- Some of these items are "almost fully assembled" or "have a minor problem" which is why they are going to be sold here and my hope is priced accordingly. However, if I say "I believe it works" or "briefly tested" or something like that, it means it turns on and makes sound. These were all in space's "screwing around with" pile, and thus, I cannot know for sure.

Once I sell around 50 % we'll do a little something for the diyaudio community, since space was such an active member for many years and looks upon it fondly. The Free Stuff (you pay shipping) section will open up to requests only after 50% is sold so please no inquiries before I indicate.

The TMOQ 834p boards and power supplies went to user tronan for distribution free of charge (he paid shipping). Inquire with him if you have interest.

Please be understanding of the sensitive circumstances surrounding this sale... no low balling, etc.

Hello. I am somewhat new to the forum. Over the past couple years if I had a question I needed an answer for I could usually find some answers just looking thru this site. I joined awhile ago but never posted anything.

I'm already 50 years in age but just started my DIY-ish journey a couple years ago. Started with rebuilding a couple ST-70's, a couple preamp kits, replacing lytics in older power amps & replacing or upgrading volume pots/attenuators.

I want to keep learning & pushing my DIY skills. Which are limited as I have no electrical background. I struggle with grounding schemes if someone doesn't lay it out all in front of me...& even then issues can arise. I am here to look for advice & knowledge...while being respectful & appreciative to anyone willing to share what they know or point me in the right direction for the information I may be seeking.

Thank you to anyone that reads this & for allowing me access to your Forum & all that it provides.
Have a great weekend!

hi all - just signed up as I've kind of started on a DIY speaker journey and this forum appears to be a great source of information.
in between work and the Euros, I'll be reading up on a vintage speaker upgrade I'm starting and will seek advice from more experienced members!

Thought I'd share some pics... we were at the Country Music Hall of Fame in Nashville the other day, and their gift shop had a pretty nifty system playing vinyl.

• Rega Planar 3
• PrimaLuna Evo 200 Tube Amp
• Tannoy Cheviots

I'm working on a project/experiment that requires the use of steep EQ curves for a 3-band EQ/tone control.
This would be easy using op amps by increasing the "poles" by adding serial active elements. I would ideally like to achieve at least a 24db/oct slope with as few active elements (valves) as possible... Absolute fidelity can take a hit here, I've accepted that this for experiment.

Is there a practical way to do this with tubes?

I'm thinking about how passive crossovers for speakers make use of inductors to increase the slope - can inductors also be used within preamp circuits to steepen curves? I imagine this isn't commonplace since it creates an opportunity for distortion, phase issues, trying to deal with the effects of Q and overall FR when the controls are at different levels (avoiding notches), etc...

Where would you place this HV delay circuit.
After the bridge rectifiers, after the first LC filter stage?

Many thanks

Evening all, need some advice plse.
Currently I use an Integra 30.2 as distribution point, the pre amp out on the Integra is only about 215mV. I use a NAD monitor 1000 preamp to amplify the small AVR output signal to drive a Slewmaster power amp. It sounds OK but I have a tube buffer that I want to incorporate for better possible results. Should I connect it between the AVR and preamp or between the preamp and poweramp for the best outcome. The buffer circuit is from uncle Hugh Dean.
Much appreciated.
Jan

In the schematic all relays are shown on. In real world only one relay at the time is going to be active. Im not sure how to ground this thing so I started with ALL pin 1 tied together, both A/B, left/right and in/out. They are also connected to input C sleeve. NOTE its shown with 6 DPDT relays but I will use 3 4PDT relays.

1. Is the grounding correct?
2. Do I also connect pin1 and sleeve to the enclosure and DC negative?
3. Can I kill unselected inputs with short pin 2+3 and tip+sleeve?

XLR Input A is Apogee Duet soundcard
XLR Input B is Stereo DI
RCA Input C is Sonos Port Media Player

Output is going to a pair of Genelec 8240A monitors.

Hi fellow enthusiasts, I’d greatly appreciate some input on the possible cause for this.

After I rebuilt the audio board and the main board and replaced all electrolytic and tantalum capacitors on them three years ago the unit worked well. It started to skip some weeks ago, and this quickly developed into the player being unusable.

As in 2020 I had not yet recapped the motor board and the display board, I did this in the last days. I was sometimes having an intermittent problem with the display not being lit after switching the unit on. That was remedied by the recap.

I also re-soldered all contacts going through the boards connecting the ground planes. Unlike the 104 this player does not have "griplets" but makes ground contacts with component leads which are soldered to the tracks on the solder side and to the copper ground plane on the component side.

I removed the solder and resoldered from both sides, paying attention that the connection was family established with the copper plane. I also resoldered all other suspicious joints.

The unit still skips however. It is reading the TOC, it does everything well, it is reasonably fast, I can choose tracks and go back-and-forth and everything seems to be functional. I sometimes it even plays for a quarter of an hour without disturbance but then again starts skipping and even stops playing the disc.

The lens seems clean. I am unsure where to look next. I don’t want to poke around in the dark.

The unit has a CDM0 drive, the one shown around page 18 of the CDM0 service manual. I also have the original Phillips test disk package. I even have a scope. But I am not very familiar with using it and doing these kinds of procedures.

As the player does sound exceptionally great and so far has been the reference in my system, I’d really like to get it going again, apart from the ambition to not give up on this fault.

I’d love some experienced opinion on this, and I’ll try to find the problem, although I won’t be able to dedicate very long hours to it in the next days due to work.

Thank you all.

Hi all

I have a question about the LC7881
DAC I know - it's a very, very old chip but it intrigued me and I want to check what it's really worth - just for fun
I would like to connect it to the I2Sover USB but I can't identify the input format for the LC7881
The datasheet is not clear to me
Can you help me?

Attached is the datasheet

Hi,
I need a preamp with selectable 3, 6 and 12 db gain between my dac and headphone amp. I don't need volume control as my headphone vol control is pretty good. I need a balanced input and balanced output. I would like it to be simple and as few components as possible. What options do I have?

I have for sale a dac with akm 4493 chip from nihtila. It sounds and measures good. It misses the caps but is done and measured by the engineer himself.
60€ registered only Europe.

Connecting ungrounded and grounded devices!

Background (copied).
Having bought new headphones with a microphone, and coming home, I was sad to discover that the microphone was creating extraneous noise. I returned to the store, where we checked on the laptop, there was no extraneous noise from the microphone. When I got home I started looking for the reason. I connected the old ones, the headphones do not make noise. I connected new headphones again, they are noisy. After some time, I accidentally touched the system unit with my foot, and lo and behold, the noise decreased significantly.

So, I came to the conclusion that there is some kind of interference on the system body. I immediately thought about grounding, and I started measuring the voltage of the case relative to the Earth. First, I took the neutral wire and was surprised to find that the potential difference was about 100V. I decided to measure the voltage relative to the heating battery, still ~100V.

I will not go into detail about where the voltage on the housings of refrigerators/washing machines comes from. Let me just say that the reason in 99% of cases is the same as in the system unit case.
You can find a more detailed description and explanation on Google.

In short, the same reason:
There is a filter in the computer power supply that dampens high-frequency interference and throws it to the ground.
Thus, we have 110V going to the ground (if the socket is 220V), but the current is only interference current, which means our current strength will be insignificant.

We get 110 Volts on the body only when it does not ground anything (including a person). With a “standard” grounding electrode of 30 ohms, the voltage on the case will be 220/(677k + 30)*30 = 10 mV (ten millivolts).
If the case is not grounded, then when a person touches it, the voltage will not be much higher: the resistance of the human body is 1 kOhm, and the voltage is 220/678 * 1 = 324 mV. This is very little voltage.

Now about the surge protector. The article says: “If you have N system units included in it, then the current filtered by each filter in the power supply will add up, and the location on the case of each system unit will be smaller.” But the current can only flow, it cannot “be in the housing”. The voltage, which is regulated in the housing, cannot change when connected in parallel.

In fact, we are talking about the fact that if you or someone else accidentally “grounds” by touching the body of the system unit, then it will simultaneously ground all other devices plugged into adjacent sockets. It is then that the currents flowing through their grounding connections add up, which leads to the addition of the voltages applied to the person.



And now to the essence of the issue.

My digital input burned out. Sometimes it is useful to have RCA terminals that are metal rather than plastic, or thermally insulated. Then you will be grounded when you take them with your fingers. Otherwise, potential can be transferred from an ungrounded device to a grounded one.

Many devices use high-frequency noise protection at the input. Those same small coils and nanofarad capacitors. So they reset half of the power potential to zero. 220/2. Yes, there is minimal current, but there is voltage. A spark appears when you connect it to another device.

And what happens when you plug the plug of an ungrounded device into a grounded one? Right. The ungrounded runs to be grounded by others.

If the terminals bodies are metal, then you temporarily become ground for the ungrounded. And you save the device. And if the terminals are plastic, then the second device receives an impulse.


There's an even funnier story there. Even if everything is grounded, it must be plugged into one socket.
Since the grounding resistance will be the same (the length of the ground route is the same).

And if you turn it on from different sockets, then the difference in the earth path will be the difference of length of this earth. Conventionally, one socket is 10 meters from the shield, and the second is 15 meters (socket on the opposite wall for example).

Now you're getting to the potential difference. Since there will be a potential difference, it will be the resistance of the length of your earth is 5 meters.
You think it's bullsh*t. 1 Meter +- 0.015 Ohm. 5 meters 0.075 Ohm.
If the device consumes 1A@220W, then at this current the voltage difference between them is 0.27V. (+0.13V on case).
And you just plugged it into another socket...

Perhaps I’m try to manipulating the concepts, and someone will say you’re a lousy electrician.
Well, to hell with it, you have potential on your case and it will go to the case of the other, and not into the signal circuit.
There won't be any sh*t.

But there is a nuance... The resistance of the analog input, for example (between the signal and zero is in kOhms. 10-20-40-100 kOhms. Nothing will happen to it. But the digital input is a 75 Ohm standard That is, a thousand times less.
Let me remind you that the operating voltage of the digital input is 0.3-0.6V only

This is a short story about how you can burn out a digital input just by connecting an ungrounded device to a grounded one.

Hi,
I'm in the building process of two monoblocks with the IceEdge 1200AS1 modules. This module has an input sensitivity of 5V, so there is a need for an input stage with some gain for my equipment with 2V output, and this stage must be balanced.
PS Audio uses this module too with a tube input stage, using a single 12au7 tube per monoblock. A simple anode follower per phase would not be very good because of the lack of common mode suppression, cathode follower has only unity gain - is my assumption correct that it has to be an LTP stage with gain? What else would be possible with only one tube to pass on an amplified balanced signal to the power module?
Many thanks in advance.

Hi All, nice to be at such good forum 😉 I'm in here mostly to get and of course share some information about NAP 250 clone build 😉

Greetings from Lithuania, long time lurker, now need help 🙂

This is my introduction. I have been an audio fan for 20+ years, automotive and home love every aspect of it.

I am a new member. I started getting into audio maybe 3 years ago. Im a electronics amateur and i try to many thinks in audio, i believe to find here many answers on my maybe not really smart question but as new in this i understand that.
I believe understanding towards me.
Kind regards.

Hi all, new member here, thanks for having me.
I like to dabble in audio stuff in my spare time, and have a small home studio set up for recording and enjoying music.

Pleasure to be here, I just wish that there was something like this forum in my day!

It's cold and snowing in Brooklyn, NY, a great opportunity to start a new thread.

I recently built these Telefunken OB speakers inspired by Kevin @ glowinthedarkaudio.com. I think it's extremely kind of him to be sharing his knowledge and experiences. Inshort Kevin helped save me time and money. I just recently started on this diy speaker hobby and new to woodworking, and the reason I choose these OB speakers is that I don't have access to computer programs that are needed to built closed or vented enclosures. I also wanted a challenge in woodworking instead of just using a broad as an OB.

I'm very happy and glad I built these OB's. I built mine to be flexible. The front panels are removable, incase if I want to do 2 or 3 drivers, or even an array of drivers. I also built 12 inch plates for smaller drivers that can be easily swapped. I used half inch plywood, if I built a second pair of these I would go with hardwood.

These OB are very forgiving, just about every speaker I have installed sounded great. Of course certain drivers sound better than others, but just about all of them displayed good imaging and separation between the high and low frequencies. The following are drivers I have used: Fostex FE208sigma, Fe168Esigma, Coral Holey Basket, Elac 8 inch, Akai 10 inch coaxial, Berman 12 inch guitar amp speakers. So far my favorites are the 2 Fostex and Coral's. I absolutely love them with my SS accupahse e202. I also played them on a brand new Decware SE84CKC. Maybe the Decware needs to time to breakin, but it's not sounding as dynamic as the accuphase. Haven't done any A/B speaker tests yet, will report back when I do. I'm curious to see if they sound better or more open then regular speakers, But my first impression is that the bass is not as tight or dynamic as boxed speakers. I'm not a bass junkie anyway, definitely enough bass for me.















Thanks for reading, would appreciate any advice.

Hey guys I'm wondering if there's a way I can make a passive RCA signal splitter in an enclosure. Do you just solder the wires in parallel or should there be some resistors or capacitors in there? I'm wondering because sometimes when I use a Y splitter to split the audio out from my TV to go to 2 different amplifiers weird things happen. I plug the first amp in but when plugging in the 2nd amp it causes the first one to loose signal. I'm guessing it has something to do with impedance mismatch or somewhere the signals are being shorted? Maybe the best thing to do is get an active splitter that uses opamps to isolate the signals and give the proper output impedance?

For sale totaly completed Janus shunt psu for tube diy projects.Verry good parts with takman resistors,nichicon caps,input mkp mundorf tubecap......
Totaly functional and ready to use with totaly new tubes.
Price 200 euro pmus shipping inside eu.

A pair of octal aikido mono pcb totaly new and unused.Price 80 euro including shipping inside EU.

Dear all,
is there anybody who can help me getting more information about this board? This belongs to a friend of mine who got in a kind of garage sale.
What I can easily understand is that it should be a converter board from a ML 30.5.

Thank you!
Gaetano

Today I built my Hypex Nilai 500 Monoblock kits and everything went together well. One thing that concerns me is the Dc Offset on both, one measures .047Vdc and the other measures .076Vdc. This seems a little on the high side for new amps and specially these types. I am running on the High Gain setting.

Has anyone built these kits and what was the DC Offset on your?

Regards
Steve

I did a fair amount of research and reading about grounding and hope I have it right.

However, this is my first build and I’ve likely made mistakes. I’m a little confused about the grounding of the PS first capacitor… used motor run caps

Suggestions please:

Hello,
İ found this schematic of an el84 6n2 tube push pull amplifier

İ need some opinions on if its worth building or should i find something else
İs it decent or garbage?
And any upgrades/replacements that can be done on the board

Thanks,

PENDING, That was fast. Thank You

I'm thinking of building a speaker with this design, (2 x 15" + 8") but maybe with a coax instead of a widebander.
Also the bass could probably be like in the XSD design? 8 x 6,5" in a SLOB.
What would be the pros and cons bass wise? The SLOB has an advantage of force cancellation? Other differences? Is there a difference in dispersion around the crossover point (400 Hz?) with these two bass setups?

I said I probably would use a coax, but has anyone heard the actual Tang Band? If it (or any other widebander) has "good enough" tweeter response, I could use my 4 channel miniDSP Flex. Otherwise, I have to swap it for the 8 channel version.

Help me figure out the problem.
Most likely, a faulty device was connected to the input (or simply static electricity from a poor grounding).
In general, the digital input stopped working (2 of 5).
There are 5 inputs (+1 output) on the board, and each chip apparently serves two inputs. All I could do was ring the resistors at the input of the microcircuits, and apparently the signal from the connectors reaches the microcircuit through passive elements.

This is some kind of microcircuit marked 74HCU04D, and then another one 74HC4094N (D2151ME) after it.
Of course, I hoped that there was a fuse somewhere along the input, but there was none. I understand that it is most likely worth starting with these microcircuits, but which one?
Apparently it’s worth starting with the first one, since it’s most likely broken (but possible next one). Perhaps many people know this implementation of digital input and similar problems.
What are your guesses?

The photo shows the Meridian DSP series 5 (561/562/565/568).

Just scored the accompanying black livery Threshold FET ten/hl with 'E' Series psu for my SA/1's

What amazes me time after time that Threshold gear seems to be so reliable.
I've had dozens of them and apart from one faulty output transistor in a S/1000 Series II, it just always work.
And bulbs for my SA/1's which I bought 50 of them but only changed two of them over the years 😉
I've never seen any Thresholds at repair-facilities. How can that be? Are they conservatively build, gone through a perfect part selection process when build, have a simple topology...?
Pass Labs will probably the same in this category.
So I do not feel the urge to replace any parts like lytics or so but maybe I should.
I did replace the eight Mallory's in one set of SA/1 and put a thermistor in them as a rushin current limiter, that's it.
Amazing stuff!

Admittedly I'm a bit of a Vifa tragic but I had this feeling when I started building speakers that using all one brand of driver made for a more coherent sound, the various drivers seemed to me to have been made to work together.

I've now managed to acquire from various sales of S/H gear a Peerless old school 8" mid-bass, one of the very good 50mm domes and as of this week an almost new tweeter and I'm idly thinking about getting a woofer to handle the bass and immediately the 12" SLS 830669
Am I the only one? Or do others of you tend to use driver families when building speakers?

Wise people of the Forum...

I'm in New Zealand at the bottom of the planet. A quiet place, however a little bit out of the way and no really good suppliers, although we can source from pretty much anywhere in the world.

I'm building a preamp and looking for recommendations for brands and suppliers of potentiometers and knobs, RCA sockets and mains power switches. Quality is the key and cost is down the list of priorities.

Who are your "go to" suppliers and brands for items like this?

Thanks in advance

As mentioned earlier in the M2OPS thread, we were able to achieve much lower distortion with 2SK3497/2SJ618 than the popular IRFP pair :
https://www.diyaudio.com/community/...-and-maybe-a-power-whammy.390636/post-7173210

We also promised to offer matched quads of those, see here for details :
https://www.diyaudio.com/community/...-and-maybe-a-power-whammy.390636/post-7179541

We have now matched 300 pairs of those and can achieve a yield of ~80x NN-PP quads.
Spec is Vgs to 3mV between NN and PP, transconductance to 5%, and delta Vgs N-P within 0.25V.
This will have no consequence in the M2OPS-type complementary follower, as demonstrated by Twitchie :
https://www.diyaudio.com/community/...-and-maybe-a-power-whammy.390636/post-7206502

At 820HKD a quad, they only cost slightly more than 2x of a matched 2SK3497 pair.
This will include registered air mail and any PP fees.
As in the past 10 years, we only can ship FOB, and are not responsible for any postage losses.
Registered mail is not insured. But HK post has been proven very reliable in the past.
What happens at your end, they have no influence though.

You are free to order multiple quads, and will automatically be given Vgs close to each other.
We also have (only) 2 sets of Octets to the same spec, out of 600 devices.
Those interested in Octets should contact me by DIYA Conversation.

We only call for payment when GB is closed, and we are ready to ship.


Patrick

Hello there.

I bought a fancypants (for me) tonearm cable, and it doesn't have any key indicating how to plug it in. I'm reduced to spinning it around to where it kinda feels like its maybe in the right position but it's a hard push and I'm thinking that I'm gonna break the connector in the tonearm and that would be bad.

But I have the original commodity cable, and it has a rib molded into it on the side of the they-call-it-a-DIN-connector-but-its-not-really-a-DIN-connector-that's-something-else where the gap is in the ring of contacts.

I also observe that the set screw for the contact block in the they-call-it-a-DIN-connector-but-its-not-really-a-DIN-connector-that's-something-else fancypants cable is kinda where the molded rib is on the Brand X cable.

Which suggests that someone intended that the set screw should be sticking out in order to provide a key.

Am I on to something here?

From 3/83. Anyone have a hard or electronic copy of this?

In this post I look at the T900A bullet style super tweeter from Fostex. This "Laboratory Series" is made in Japan unlike lesser models. The tweeter uses an alnico magnet along with a magnesium ring radiator diaphragm. Other than that, there's very little information online for this particular model.








The front of the tweeter is made from solid brass which has been lathe turned and polished.

Disassembling the tweeter reveals clock work precision internals.

Measurements​

I began by measuring the impedance sweep. The Fs is actually quite low at 1885Hz with a second peak at 5685Hz.



Frequency Response

The response shows a large peak centered around the driver's Fs however this is below the usable frequency range of the driver. The response is flat from 7kHz-10kHz with a peculiar +4dB HF shelf. Response is then flat again until 21kHz where we see a mild breakup mode in the diaphragm. (click to enlarge below)



If we compare this against published we do not see the HF shelf at 10kHz. We also do not see extension to 30kHz with my test data.



The off-axis at 0,15,30, and 45 degrees off-axis shows a considerably wide coverage centered around 7kHz but quickly narrows above 11kHz. By 15kHz the listening window has narrowed to only 60 degrees.



Burst decay shows a mild resonance at 21kHz, otherwise we are trouble free.





The CSD plot shows the typical stored energy at Fs (4.8kHz). The tweeter remains clean above this with a very fast decay time across it's usable bandwidth.

Distortion​

Looking at harmonic for the 85dB 1m test signal, we see H2 dominate however still moderate in level at only 0.42% at 10kHz. H3 and H4 remains well behaved.

The 95dB test signal shows H2 rise in a linear fashion as expected across the frequency range. There is nothing too concerning here.



Intermodulation Distortion

The below test was done with a 6th order high pass filter at 8kHz. This was done within the Hypex FA123 filter software.

Using a 12 band per octave test signal we see a subtle rise in IMD at 10kHz dropping to very low levels in the 15kHz region. Distortion is lower than many amplifiers I've measured in this region, so pair carefully!



Raising the the test signal from 85dB to 95dB 1m we see IMD rise in a linear fashion with 10kHz showing 55dB dynamic range improving to 74dB at 15kHz.



General Considerations About Bullet Style Super Tweeters

The Fostex T900A is an attractive solution for covering upper treble. Care should be taken to high pass filter with the correct frequency and slope. This will help keep intermodulation distortion at bay in the audible band. The 85dB and 95dB test signal is likely higher than normal use case listening levels, so the projected distortion represented in my test data is likely much higher than in real life use. Considering this, amplifier choice becomes paramount in order to ensure low distortion performance, otherwise the tweeter will likely take on a somewhat harsh sound character. It is suggested to use a low gain amplifier since the tweeter will only require around 0.1v in order to provide optimal listening levels. If you are using a high gain amplifier, you should attenuate the tweeter using an L-Pad circuit or Autoformer. This ensures you are out of the noise floor of the amplifier.

Conclusion

The Fostex T900A is a well executed and beautiful tweeter with very good objective test data, particularly in the time domain and intermodulation distortion results for the upper treble region.

For the Marantz 9's. How hard does it push the small signal tubes? In particular the 6DJ8's?

How is the Marantz pushing 310 volts on the plate when the tube itself is rated for 140 volts maximum? I assume it's referring to plate supply voltage (= peak forward plate voltage?) which is much higher at 550 volts.

If I were to use a near equivalent tube of 165 volts max plate voltage but a peak forward plate voltage of 330 volts would it work? 1 watt per plate dissipation. Last thing I would want to do is risk blowing the amp.

Hi!

This will be my second project using a waveguide created with ATH4
https://www.diyaudio.com/community/threads/acoustic-horn-design-the-easy-way-ath4.338806/

My first project is here
https://www.diyaudio.com/community/threads/hf10ak-12p80nd-custom-wg.360973/

Those speakers have been used to good reception at my local church for charity "cinema" nights. They have now ended up forming the speakers of a Hauptwerk based organ. Sadly the 1960s pipe organ is beyond economical repair.

The new design continues the use of the same parts with a slight tweak to the waveguide depth to align the acoustic depths of the HF10AK and the 12P80ND measured during the development of the above speaker.

I hope to manufacture them in such a way they will look like the attached. Dimensions and driver positions not set in stone.

Parts

1x HF10AK + custom waveguide
1x 12P80NDv2 rear ported exponential aperiodic
2x 18H500 in a 7cuft3 sealed box
custom active opamp crossover
Neurochrome "Done Right" amps

More to follow.

Just noticed this new driver on Solen:

https://solen.ca/en/products/bliesma-w137t-854-137mm-textreme-dome-midbass-5inch


Bliesma-level pricing of course but looks like a nice driver. Less pronounced breakup compared to their metal and paper dome midranges. The low sensitivity means more bass response. Seems like it could work well with a simple crossover and lower crossover frequency than their other drivers.

As title said I'm looking for a Zobel to tame the ringing OPT at 8010Hz, how can I calculate the proper values for R & C.

TIA

A friend of me tell me, that various devices of this model suffer from this problem - the noise when playing quiet music is unacceptably high.
The device reviewed under
https://www.stereophile.com/content/rotel-michi-p5-preamplifier-measurements
apparently does not seem to make any audible noise.

Does anyone happen to know exactly which serial numbers are affected and which upgrade measures need to be taken to solve the problem?
Thank you very much for an information

While trying to fix a family members dead sub my Presonus Eris Sub 8 has decided to mimic gale force winds for some reason. I checked everything from trying a different wall socket, removed inputs and outputs, and checked to see if the volume has any effect (it doesn't)

I have read that the cause is likely a leaky DC filter capacitor which would make sense, but I don't have a schematic for this power supply and don't know my way around them well enough yet to know which might be the likely culprit.

I did also notice a few dry solder joints but would they cause the issue?

I’m having a hard time getting my head around the final baffle losses of dual opposed drivers on a three way speaker that is shallow, ie narrow baffle as seen by the side firing drivers. I’m assuming it’s a complicated relationship between standard baffle losses and driver directivity, room gain and potentially each driver’s waves combining at the front and rear and adding for higher efficiency at some point? That last point is the one I’m particularly unsure of.

The plan is a wide baffle, shallow three way that may be suitable to table top and near wall positioning. It uses the GRS Neo 3 and 10 which I already have sitting on a shelf for more than a year and Dayton ND105’s with matching PR’s. I took some inspiration from the Lyngdorf Model S as far as form factor goes.

I might being trying to force something that just isn’t worth it and won’t work that well, but I’m trying to do something different and interesting with the GRS drivers that I now have laying around since I scrapped the project I bought them for. For one, the combined SD of the woofers will only be about 102 cm, sensitivity 88db on a really good day and I’d be crossing way higher than normally advised for side mounted. I’d love any feedback one way or the other. Thanks in advance for any insight!

Hi all,

I'm wondering if anyone might be able to help. I'm looking for the manual for this turntable, It's a Sugden Connoisseur 2-speed turntable rebadged for Knight.

https://cdn.shopify.com/s/files/1/0885/5784/files/sugden_conn_large.jpg?v=1487604127

Does anyone know whether a manual actually exists for this?

I'd like to learn more about how to maintain this turntable (oiling etc,).

I also have to sketch a diagram of the motorboard (fitting a non-improved SME 3009 tonearm) for a craftsman who will build a motorboard for me. I wonder if the manufacturer offered any templates.

Any kind of help or advice would be very gratefully received.

Hopefully I can find some assistance here. I have two Denon AVP-A1HDCI preamplifiers, each with different issues. Both power on and work from one degree to another. The first, I paid $200 for. I believe it has a failed HDMI board. Optical inputs work fine. HDMI monitor out functions and I can view and use the menu through my TV. However, when I plug my Denon DVD-5910 in to it, the DVD player freezes and I can not use any functions on the DVD player until I unplug the HDMI cable and shut off and turn back on the DVD player. This occurs on any HDMI input port. (HDMI cable is fine. I can plug cable into my TV and it functions normally. I have been using it this way for the time being and using an optical cable from DVD player to preamp with nos issues). The second unit also powers on, the HDMI board seems to be functioning. I can use the same DVD player and HDMI cord plugged in to the preamplifier and plug the TV in to the monitor port and the DVD player functions normally, produces sound and picture; however, the sound is low and hollow (almost like a bad ground). In addition, the optical input produces the same weak sound, but has the additional issue of cutting in and out. I am thinking a failed digital audio board (rca inputs produce full sound). Some additional issues with the first unit. I have not been able to use the Denon link with the DVD player. Also, the Audyssey mic worked the first time I used it, but gave an error of not hearing it the next time. The second unit will run Audyssey set up with same mic, but sound is to low register (same weak sound). I paid $50 for the second unit and it is mint looking. As such I am hoping to make use of it. These units are packed full of components. How difficult are they to disassemble and swap boards around in? Any other suggestions as to where to start? Thanks for any advice.

Hi there!

I have Adam Halls LD Systems XS400 (china?) amplifier. When it come to me it has blown psu as I find later because of dried primary bank elco. I have replaced all destroyed parts:
P1F should be Rohm PZT2222A
13005A replaced by MJE13007
(2S)C4138 replaced by J13009
For R10 and R16 im not 100% sure because of massive damage but I think it was 4R7
And of course, both primary bank elcos.

With all parts replaced amplifier worked normaly but after 14 days of use blew whan turned on. I replaced damaged parta again and trying multiple power cycles and eventually after some 20 it blew.

Do any of you have an idea what could be the problem with it?

Best regards

We had a couple of accidents causing one PR to have two dimples in the dust cap.
The second PR has one dimple in the dust cap.

$125 shipped for both passive radiators.

PTT6.5PR-NA2-03

Passive Radiator # 1


Passive Radiator # 2