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

For days I've been racking my brain over all the possible (and impossible) options for a subwoofer for my particular listening situation. The room is unfavorably dimensioned and the neighbors are sensitive. So I think about how to minimize room excitation.

My latest brain fart looks something like this: An DSP-driven (so with appropiate equalisation and delay) open-baffle woofer (for example https://www.sbaudience.com/index.php/products/open-baffle-drivers/bianco-12ob150/) about 20 cm behind my head, integrated into a large absorber attached to the rear wall with 9 cm spacing.

The absorber consists of a 6.5 cm thick wooden frame covered with canvas on both sides. Behind the canvas are 5 cm thick hemp fiber insulation panels. My idea is to integrate the woofer into the absorber behind the front canvas so that it is as solid and vibration-free as possible (I haven't thought about the details yet).


I practically never listen to music louder than about 80 dB, so the woofer shouldn't experience much excursion.

In principle, what do you think of my idea - worth a try or nonsense?

Is it necessary to install a RCL circuit in the speaker crossover when driving them with a tube-amp
To make a impedancecorrection?
Because of the tube-amp impedance rise at 1000 Hz.?

Hi all,

I'm quite out of touch regarding diagnosing faults in CD players - I was never that good at it anyway. However, I recently was given a Sony x779es player, beautiful condition, and it seems an awful waste not to try to fix it at least. The laser sled is KSS272A which of course is unobtainium. The unit looks completely original inside, and doesn't look molested in any way. No caps are swollen, although I did look at some surface mount electrolytics on the motor board itself and they were very high ESR, so I changed them out for new ones.

Of course its not reading CDs. It takes the disc in, the laser head moves up and down to focus, I can see the faint red laser beam, it does the reflective surface check and will spin up the CD. Then after a quite short spin, maybe 5-7s, it stops and the display reads "0".

From reading around, this means that the focusing is working, the laser is not dead, and the motor etc is probably OK. The sled moves on magnetic rails, everything moves very freely, and the head is moving right to the end of its travel to the centre of the disc. I don't think its mechanical at this stage. The fact that maybe the laser is OK, and the fault is elsewhere gives me some hope that perhaps this one can be brought back from the dead.

I think I have read every thread on this player on this site - most of which end with no resolution as you'd imagine. All say not to touch the focus gain/tracking etc on the laser head and the total power output is automatically controlled as far as I can see. Because its not reading, I don't think I can get an eye pattern, so its just that little bit tougher.

Could anyone give me any pointers to start into this?

Many thanks for reading so far!!

Hi everyone. Longtime lurker, first post here.
I’ve always loved the Tc9fd-18. 2 weeks ago on randomly on Facebook MP a guy is selling new old stock TC9 very cheap, so naturally I bought a box of 45pcs. 😎

I have in mind a straight array using 24 pieces each side. I plan to use dsp to attenuate/shade, add various amounts of delay, and low-pass the drivers based on the wavelength/line length ratio. I have a dsp box with 24 output channels, and am exploring amp boards from China or 12ch zone amps to have 24 channels of amplification.

My room has 7’ ceilings, so the array will cover 94% of the height.

Right now I’m trying to understand what issues might come from a delay-curved cbt array going floor to ceiling vs going infinite line/no delay.

the nice part is I’ll have the ability to adjust delay/attenuation/roll off pretty finely once it’s all assembled.

I’d love to hear any tips or cautionary tales anyone has or has seen for tc9 line arrays.

Unrelated but im putting danish oil on my current project: open baffle H frame with grs18-pt woofers. Then im going to get started on this array. hoping to do the CNC this summer and the wiring this fall and winter.

I have a DDC which uses a range of WIMA MKS Polyester, electrolytic and a few PP capacitors. WIMA in general, I've always found can be bettered more often than not - question for the group, what generally is the best more accurate capacitor type for digital audio circuits, is the MKS the best it gets for noise, stability, DA, ESR etc. Could or would it make sense to consider other types where space permits?

Looking at MKS caps around the power section, inputs, and more. Would be great to get some thoughts on this. Thanks!

One of my Parasound A21's developed a problem and, without a schematic, I'm not confident in fixing it...nor do I want to send it back to CA.

Problem description: Amp turns on okay, with the "P" lighting normally. However, the two blue power lights do not change intensity, nor does the relay click. Nothing seems burned so it appears to be simple component failure.

Does anyone have an A21 schematic? Suggestions?

I am Building a Pass Labs Aleph 5 clone and I bought some used capacitors for the PSU from local ads.

They are 2200uF to 5800uF, with voltage rating ranging from 100V to 400V. I know I only need 63V capacitors but effort trying to get used 63V, >10000uF capacitors was futile, so I jumped onto getting these uniformly sized high voltage capacitors when these appeared on the local ads, at a very reasonable price. Beggar can’t be chooser.

I will be equipping myself with power supplies and general voltmeter and ammeter to reform these capacitors. I intend to reform them to 80% of their rated voltage and that should be more than enough for my usage.

Q1) Is there a need to reform them to 100% of the rated voltage do that they are fully “reformed”, even if I will be using them for less than 63Vdc?

But before I reform them, I would like to test if the capacitor is still good, to avoid any mishap during reform, as well as testing them after reform.

From what I gather, I need to test capacitance, ESR, leakage current of the capacitors to determine if they are still useable. I have multimeters and I am buying a DSO and a signal generator. From the YouTube video that I watched, I would need a LCR meter, ESR meter and a leakage current meter.

Q2) Please could you recommend a meter that can do all three? I do not repair electronic equipment for living, but I do attempt to repair simple household appliances, strictly hobby purpose and my budget is <USD200 for the meter(s)

Thank you!

p/s: I have training in electronic engineering 35 years ago, but only worked on system level for most part of my career, I haven’t forgotten my basics and I am fully aware of the dangers of dealing with high voltage but that is about all.

This thread is dedicated to a new 125W amp, about to be born at Aspen.
This will use bipolar output devices, with two matched pairs. Some of the brochure information is attached, and I will add to this in the next few weeks.

Beginnings

I walked into my workshop a year ago and surveyed the inventory. Hmmm. Too many bipolar transistors; small drivers (C4793 and A1837), and large outputs (C5200 and A1943). I resolved that I would design an amp using bipolars again - like the AKSA, Lifeforce, and Soraya - so that I would use these excellent semis before I fell off the twig.

Evolution

I examined my hit rate with amp designs. The early bipolars were very successful, particularly the AKSA, the Lifeforce, and the Soraya - and since that I have been able to refine my front end and VAS stages quite a bit more. So, I thought that I would use a singleton input, a buffered VAS, and a hybrid CCS/bootstrap. Yes, that would do it.......

Choosing the power

I have the SAKSA at 85W, and the Maya at 200W. I needed something around 125W, and at this middle power I could use only two matched paired outputs, like the AKSA Nirvana. A superior power supply bridge comprised of UFSR diodes (used in the Maya and SAKSA) has now been added. A more powerful amp would need three or even four matched pairs; that is an expensive and difficult exercise, but matched pairs is practical and a large number of raw devices yield a lot of pairs.

Layout

I have a lot of excellent new cases, built for the SAKSA. I thought a monoblock Titan would be very appealing; you could fit one channel with a 300VA toroid in one box and the thermal dissipation could avoid the expensive heatsink since the box material is single piece 3mm Aluminium.
I created the first pcb, had a few manufactured in Shenzhen, and then slowly stuffed two for my prototype.

Above is the prototype pcb, with the production version being more refined.......

Market Information

This completes my range; from the 85W SAKSA to the 200W Maya. It will be offered very similar to the Maya; monoblock, one large 278x71mm pcb per channel, two independent power supplies each of 52V rails and high speed diodes, and full DC protection for the speakers.

I expect a batch of 30 before Xmas; price is now finalised and will be $USD3k for a complete pair of monoblock pair, plug 'n play. For DIY, the two modules, with heatsinks, will be around $USD1450, mid-price between the SAKSA and the Maya. The surreal presentation, resolution, slam and imaging is stellar, up there with the best high end, and if you have 88dB/watt/meter 8R speakers I can't see any point in using the 200W amplifier.

Thanks for the interest, this Titan is a very good amplifier, I'm quite proud of it.

Cheers,

Hugh

I retired quite some time ago from a career in Radio Tech & Data. In the late 70's I built the Powertran 75W + 75W Linsley Hood amp and drove 2 Bailey TL cabinets. The amp was packed away for the decades and now I'm trying to resuscitate it. Age hasn't been kind to some of the transistors which have been replaced, but I'm now struggling with the power amp boards and achieving the desired AB standing current. The amp goes into oscillation and draws lots of current( if I let it) notwithstanding that before it misbehaves, I can measure about 0.75v as the offset voltage on the output. I wondering if some oldies are still familar with Hood's DC circuitry?
Cheers from the deep south and its Winter.

Many people in DIY mentioned MELF as their top choice for SMD resistors.

MELF are regarded as better than thin film by the manufacturers and the reasons seem to be reliability, durability, long term stability rather than real time electrical performance...
these things are obviously important in audio to some extent, but I doubt normal high precision thin films arent already more than good enough in this regard.

Im sure both are also more than good enough for any audio circuit in terms of electrical performance but I would think flat thin film would have slightly less inductance than cylindrical MELF.

Based on some recent browsing it looks like good quality Susumu RG thin films come in higher tolerance and lower tempco for the same price as MELF too.

MELF fill the gap for higher power precision SMD resistors but unless there are other factors im missing for typical 1/4W needs I dont see any advantage.

Hi all.

Just thought I would post this thread, showing a few internal pics of the Gemsound PA-4505 amp (400 watts -8 ohm / channel). - According to their data anyway...!

I haven't had a good chance to put it through its paces yet, but the power supply seems to be a bit better than the old EXA series.. But I do wonder how you can get "400 Watts" at 8 ohms with less than 63v rails (see photos of power supply caps)..

Sansui transformer C1590XX D521, trying to find a like replacement ?
Power requirements: 120/220/240V
8 wire leads on both sides of single unit with two coils
Original stock number: 15010402

WTB Used Modi 2 that works, no intermittents. Does not have to look good as long as it works.

joedawson at

itv-3.com

cheers

pos

I am looking for a replacement for the J-series tweeter from the Jamo company from the 1980s. Does anyone know a speaker with a similar sound, I really like its sound in electronic music. What type of dome is there? Silk or something else?
Is the dome from Heco Psm 1000? Could it be similar? Their speakers in those years were quite similar.

Hey guys, I am running into an excursion problem when modelling a ported 650 cubic inch enclosure with the Seas Excel W15CY-001 5.5" Magnesium cone woofer.

I seem to hit Xmax at only 12 Watts. Is this normal or am I doing something wrong? I downloaded the data from Loudspeaker Database and imported to WinISD without any modification. I use the Butterworth preset.

Here is a graph at 35 Watts. I have not added any filters.

I have read on a few forums that predating the introduction of the 6as7 (radiomuseum says '35 but the oldest schematic I've found is '38) that many other large, low mu triodes were used as pass tubes or regulators, including the 300b. However I have never seen any of these schematics. Does anyone happen to have one to share? Does anyone have any interesting tid-bits on the development of dedicated regulator tubes?

...and what's the oldest HV DC tube regulated circuit that you're aware of? When did those designs pop up? Were other triodes used multi-purposefully for that role before the 300b? I'd imagine tubes like the 45 would work fairly well. Not that I would use one that way... just, curious...

I just can't seem to successfully search for such a thing, since the internet is so densely populated with hits for any search including "300b."

Hi everyone;

I would like to know if anyone knows how I can see the frequency response of a speaker with 2 or more woofers of different models and different Thiele-small parameters.

They told me that I could calculate the Vb of the box by averaging the Fs, Qts and Vas parameters of all the woofers, and use those averages, and I already did it, but now I want to see the response that the box would have

Hello everyone,

I've recently inherited a pair of Altec Lansing VOTT A7 speakers (with 511B HF horns) and would like to restore them. The previous owner made some modifications, including adding insulation inside the cabinet and moving the HF horn inside. They were originally purchased around 1975.

One speaker works fully, but the other has no sound from the HF horn. Suspecting a bad HF compression driver, I found both drivers labeled 802-8D, but one is marked "Symbiotik." Upon inspection, the diaphragm and voice coil in the working driver (labeled Symbiotik) were easily removed, while the non-working driver’s assembly seemed fixed due to attached terminals. I did not force this assembly apart. Testing showed faint sound from the faulty driver; both drivers read 2-3 Ohms on a multimeter. Swapping the drivers confirmed the crossover is not the issue.

I've contacted Bill at Great Plains Audio about replacing the diaphragm and re-magnetizing both drivers, but have yet to send them in. Additionally, I'm interested in refinishing the cabinets and would appreciate any advice or tips.

Here are some images for reference: VOTT A7 Album

Thanks,
David

This thread is about the new lineup of 3” dome mids from Bliesma. There’s 4 different versions. Alu/mag, paper, silk and Beryllium. Please feel free to share any thoughts or experience about them. Datasheets for all below:

https://solen.ca/wp-content/uploads/M74A6.pdf

https://solen.ca/wp-content/uploads/M74B6.pdf

https://solen.ca/wp-content/uploads/M74P6.pdf

https://solen.ca/wp-content/uploads/M74S6.pdf

Hello, Greetings from Bali.

Currently on an extended holiday at the moment but hoping to get back to reality by Autumn time.
Just picked up an old set of Klipsch speakers for next to nothing so hoping to rebuild the crossovers when I get back to Europe.
Worked in Engineering for 20 years but the last couple have been in Electronics or Electo-mechanical assembly. I'm here to learn from those with more experience so I can invest wisely in test equipment for a lab to hopefully test and repair audio equipment and to learn about useful resources to accelerate my Learning Initially it will just be a hobby.

Cheers

Paul

Just did some maintenance on one of these classics. Class A preamp, they run warm. After recap, noticed this one is idling even hotter! There are a number of pots, I'd like to check bias settings, I asked Krell about the procedures and targets - and of of course nothing 🙂.. Anyone have suggestions on adjustment targets for this beast? I measured ~60mV across the resistors. The pots in the center control adjust both resistors, unsure the TPs for the pots on the left.

After hearing so much about MiniDSP projects and having gotten my appetite wet by the iDSP from OSD I bought one.
I had a rocky road with the iDSP app initially regarding to to the auto room correct function to generate FIR filters I got it ironed out.
I didn't use the iDSP for subs but instead used it in an expanded implementation with an XO at 300hz to the woofers in my speakers which were already designed as an active system to get better baffle step and LF room correction.
The IDSP is the same board as the Parts Express DSP unit but with 2v out in mono and nice RCA's vs 1/8" jacks. Same software as well.

I decided to try the Mini in my next active XO project and as a first step I substituted it for the iDSP in an already well sorted system.
The result using the panel to configure the Mini was terrible!! The filters had terrible ringing and a huge loss of transparency.
How could this be I asked myself. The iDSP is dirt cheap vs the Mini and the Mini has far fewer features relating to dsp built in to go wrong.

We all know the Mini panel is very basic but allows the more complex FIR filter import through either plugin (Dirac) or 3rd party FIR filter generators

It turns out that the Mini built ins are IIR filters for simplicity vs the FIR based iDSP and it is clearly audibly better with FIR based filters.
Unfortunately to access the much better sounding FIR based adjustments for the Mini we need to spend a bunch more, a WHOLE BUNCH MORE!!
As a baseline the iDSP has dynamics, phase, delay, limiters, Sub harmionic synthesizer, Dynamic bass control, parametric eq plus the XO up to 48db. The iDSP is doing all that via FIR based filters, which makes sense as IIR filters would fall apart with so many complex filters, and does it via the iPhone app and it's only $5 to buy the app vs hundreds for DIRAC or Eclipse Audio's program.

Granted in the grand view of what I have invested into my system several hundred bucks is cheap but having such great sound from a $50 unit has me pissed that it's going to cost and be far more complex of a process.

Hello all. Hoping someone on the forum can help me out with this problem. I recently acquired a SP20E preamp that has nothing but a loud buzz coming from the outputs. I see a couple of potential problems that my/may not be contributing the problem.

1) Appears to be a missing resistor - see photo
2) The the second smaller toroid has two taps tied together 1.9+2.9 but the board input appears to require 9V

Can someone share some insight if the above will have any impact (ie is that resistor location meant to be empty and is the existing toroid acceptable). If these two issues are fine, can you suggest where to look for the cause of the buzz and where to find a schematic. I've reached out to Dan at Tubes4Hifi but not yet received a response. Much appreciated.

Hi everybody

I am new here but not new in audio designs specially for ESL and Tube amplifiers.
My normall interests lie in electrostatic speaker designs in combination with tube amplifiers, all do-it-yourself. All aspects.

John (off Johannes)

[Moderation edit: This thread split from - https://www.diyaudio.com/community/threads/monsoon-speaker-parts.391848/ ]

Thanks woody for the monsoon planars. Since this is already in the right section, i will post the measurements data here.
Lets start with mh-700.

When you want to ship overseas, you keep it strong and impact resistant obviously, but as small and as light as possible. I am soon to send a pair of tweeters across the water. The cost is astronomical as you go up in size and mass. Hmmm... nothing around the right size at home but there is some large cardboard boxes in the basement. This is what happened.
Measure what you need, lay it out and cut it up.
Figure out how you are going to protect the contents on all six sides
Go to work with your box cutter and tape.
The inner box has a pair of Aurum Cantus G3Si tweeters. Top and bottom are the foam board sandwiches and sides use cardboard rolls in the sandwich.
Bon Voyage my precious little ones.

You may also be interested in reading my story on the repair of a Krell KSA250 link below

https://www.diyaudio.com/community/threads/krell-ksa-repair.402617/

After repairing the Krell 250, I proceeded to upgrade the amp which deals with the power supply section. The first one is an easy tweak which all modern audiophile grade amplifier incorporates. This is to bypass the large electrolytic filter capacitors with small value high quality film capacitors. In this case I use 1.0uF 100V polypropylene film cap. Four pieces, one across each of the 68,000uF capacitor.

Used these briefly, but decided to go in a different direction with the project. 2x JBL 2445J compression drivers (1987 date stamps) with 2x 2380a horns. Drivers are completely functional, and horns have no cracks. I'd prefer to sell these together, but will consider offers for the horns and drivers (in pairs only).

Asking $600, local pickup preferred, but willing to ship.

Onsemi has the complimentary part Spice model but not the KSA1015!
Could you share a copy if you have one?

Cheers

I am trying to find a schematic for my Sansui RG-700 graphic equalizer. I did a Google search and nothing comes up except a four page service manual that does not have any schematics. Can anyone help?

Hi to Everyone !
at least for me one of the objectives of a recording is to be able once played back on a very good system to provide a realistic sensation of the original musical event
I'm obviously talking about pure minimalist recordings with no eq effects and so on
And consequently a system must be able to give back that sensation of listening to something live, perhaps when listened in the dark or blindfolded
I wonder if the movie sound effects which nowadays are recorded with incredible quality are not extremely useful to evaluate this ability
I asked myself this some time ago while watching a DVD whose title I unfortunately don't remember
The scene was inside a laboratory in a control room separated from the actual lab by a safety glass
At a certain point an actor from inside the laboratory rapped the glass with his knuckles
I jumped. It wasn't a reproduced sound. It was a real sound
It felt like a person was inside the television and tapping on the screen. My friend and I heard it several times and we agreed that the sensation was incredibly real.
For the record the chain was $80 Samsung DVD player > Revox b150 > quad esl 63
Since I didn't have much money at the time, I only bought the Samsung DVD which I later found to be quite good even with normal music. Very good indeed actually.
So can high quality sound recordings of real sounds be a good tool for evaluating easily the capabilities of a system instead of music?
I think so. In fact, I'm convinced of it

Hi, this is a pair of Jensen JT-DB-E DI (direct injection) transformers, unused. These are a 12:1 ratio transformer designed for stepping down line level for input to microphone preamps. One (on the right) has some tarnish from sitting open on a shelf. I don’t have mounting brackets but they would not be hard to make.

Specs/info here:

https://www.jensen-transformers.com/wp-content/uploads/2014/08/jt-db-e.pdf

Max input signal level is 22dBU (10V), however they can be used with higher signal levels (eg power amps) with additional attenuation as in this app note:

https://www.jensen-transformers.com/wp-content/uploads/2014/08/as008.pdf

Price for the pair: AUD250 (PayID/EFT) shipped in AU, EUR167 (SEPA/Wise) or EUR179 (Paypal) shipped to EU. Other locations please enquire (FYI not a great deal for USA due to high cost of international shipping).

Thanks, let me know if any questions 🙂

[SOLD] For Sale - Used Edcor XPWR008-120 power transformer.
PRI 120V
SEC 600V 200ma, 6.3V 4A, 5V 3A

$95 , free shipping

SOLD : Used Edcor CXPP-25MS-8K 23% Screen output transformer pair
25W 8K primary, 4,8,16 Ohms secondary

$150, free shipping