Ok so looking at those 2 tubes.
Which one would be the most linear?


The 811 has a High Mu so looks more like higher rp and more distortion.

The 812 is lower Mu so would have lover rp and less distortion.
It will need more clean drive probably.


The 811 was used in the altec 1570
There is also the PFB-150WA and reading on the internet suggests the load impedance of the output was around 1650ohms which is very low I think, Should be more like 5 or 6k



So the question is what to use? 811 or 812.
can they be used around 600v?
The grid will need some heavy positive drive but A source follower can work.
Or else a kathode follower but this will be a small power tube. (6BX7)

It's just thinkering when I was reading about the 811 tube. They look really nice also.

And they are also not that expensive.

The Warpspeed came about to address some of the shortcomings of current LDR volume controls. On the list are:

-the inability to adjust to complete silence
-on low/high volume level settings, power levels on the LEDs endanger/shorten/toast the life out of the optocouplers
-the need to improve the power delivery to the optocouplers
-the need to improve on quality of the volume adjustment pot
-the Lightspeed, simple as it is, still has a number of variables/design factors that affect performance

The Warpspeed solves the above and then some. Added bonus are:

-low volume levels are more engaging and equally enjoyable (ie. the music details are as much as when at moderate/loud levels)
-low volume listening is perfect in conjunction with NP's monotonic amps -decreasing distortion at lower audio levels (might explain above experience)
-wider range of volume level settings
-battery power means less ac power related artefacts on optocouplers
-precise power delivery and control at safe levels on optocouplers
-by design keeps optocouplers' power level ratio at/near equilibrium
-peace of mind at any volume level

Forgive me for what may sound like a controversial choice of name...some of Star Trek's storylines are still controversial and significant to this day.

More to come soon...

My UGS UP! power amplifiers - The French Connection I.

You know me, I'm a wacky trouble seeker, and I usually found it.
(It is enough to mention my marriage, which lasts now for more than 33 years.) 😉
Moreover, I'm an addict to Pass amplifiers.
These are like heroin for me.

Years ago decided to build an UGS UP!.
The time is here to strenghtening The French Connection.
I have most of the parts, including two Modushop Dissipante 5U H210 chassis.
Now, as I've looked some UGS UP was built by some DIYers, perhaps this 5U unit too big for one stereo pair.
Although I have secret plans.
And I have some questions as well:
Can I build two stereo pairs of UGS UP in one Dissipante 5U chassis?
What is the most power it can dissipate?
Or, (it is the secret part now) can I duplicate numbers of output MOSFETs?
If yes, what parts I need to modify?
I know, this amplifier is a carefully designed piece, and if I modify it,
(with my zero knowledge) it will not be the same.
So I certanly need suggestions for this.
I have some trouble with 2SA1209/2SC2911 pairs, I don't have enough now.
So there is another question:
Can I use Toshiba TTA004B/TTC004B pairs?
I know, original 2SA/2SC pairs quite unusual ones, quite high Hfe and very low output capacitance.
So even if I can use them, the amplifier will not be the same, I suspect.
Any advices are welcome!

Kind regards,
Wacky Gyuri

Overview/Survey of Record Player/Turntable Measurement Results wanted

There are an extrem wide range of such devices.
Even very many test reports and listening tests was performed - e. g.
Turntable Reviews | Stereophile.com
The Big Turntable Comparison | HFA - The Independent Source for Audio Equipment Reviews
Pioneer PL-L1000 | zStereo
New GT-5000 Turntable Yamaha | Steve Hoffman Music Forums

Any small overviews of such devices:
REFERENCE COMPONENTS-TURNTABLES
https://moneyinc.com/most-expensive-turntables/
https://www.digitaltrends.com/home-theater/most-expensive-turntables/
https://web.archive.org/web/20080614160818/http://www.higherfi.com/audio_phono/sa
https://www.pinterest.fr/bilonolivier/platine-vinyles/
https://www.hifistatement.net/tests...ham-phantom-elite-und-techdas-tdc01-ti-teil-1
Word's most expensive record players: Dereneville VPM2010-1
https://www.rk-rose-krieger.com/deutsch/aktuelles/presse/anwenderberichte/highend-plattenspieler/
https://www.avsa.co.za/zero-compromises-for-ultimate-techdas-turntable/

But where are to find measurement results ?

This is a very rare exception:
https://static1.squarespace.com/sta...41acad/1489563683682/Plattenspieler+Audio.pdf
https://www.stereophile.com/content/linn-lp-playing-system-measurements - go also to
https://www.hometheatershack.com/threads/using-rew-for-vinyl-measurements.142634/

Maybe one of the members can upload measure results from various top class record player/turntables reviewed in various magazines.
Overview from world's best historical and currently available electr/audio Magazines

Thank you very much.

As Connex electronics wants more that the SMPS costs in shipping...
So what other palces is there to buy SMPS? 😕

Oh boy.
If my body's reaction to the vaccine is anyhow related to what would be (have been) a real infection, I'm kinda glad I had it this way.
Phew! 40 hrs almost nonstop sleep, pain, cold, younameit... but I'm through, HA.

This is a general question, not related to any specific sound card or Windows version.
If you drive an USB sound card into overload on its input, you can reduce the record audio level in the Control Panel - Sound - Record - Properties - Signal level
This control goes from 0% - 100%. What does it actually do? How does it interact with the sound card? Does it do some kind of digital attenuation? How could I get the best S/N? By increasing the analog input level and apply the Windows attenuation, or set the level back and push the control to 100%?
Also it is a bit disturbing there is no VU or dBu scale, neither VoltsRMS or any common level reference. You never know what is the actual level at the input of the soundcard, and how is it scaled to the digital domain, referenced to digital full scale.
I suppose Linux is not different either.
Any ideas, comments?

Do you think it is manageable to get spdif coax otput from this card?

As far as I know, the signal is spdif coax - with some small opto-electronics and resistors, just before the toslink ouput.

I think of soldering some shielded cable, dril the bracket and mount a bnc connector, isolated from the bracket.
BNC in order to get the standard output impedance, if possible.

Hey guys,

Listen to 2 speakers playing in stereo aligned in a way you can't notice the stereo image is better than you listen 1 speaker in mono? The final SPL would be set the same, both PA are the loudest in technology. I want to know about sound quality.

Paul from PS audio said in this video that the lower distance between two speakers more midbass there will be. So 2 speakers together will produce more mid bass than 1 speaker, is it right?
Optimal distance between loudspeakers - YouTube
Link of video

I would like to know if I should set 2 speakers and play in stereo or set up 1 speaker in mono because it takes more time and physical energy to set up 2 speakers than only 1. Because of the listen position does not allow the stereo perception.

Its almost impossible to hear in stereo if you have a walkable venue and cant have a equilateral triangle sweet spot what do you think?
Do you prefer to listen in mono or stereo?

HI Guys,

I decided to go ahead and get myself the the dual Ak4495 Dac (weilang Board, fully assembled), and have hit a strange Problem.

I have used the xmos usb interface to connect the Dac to my Mac, however the interface is not detected by the Mac since the Led on the xmos board doesn't light up every time.

I have to turn On and turn off the dac's power button several times (10-15 times)to ensure the power light comes ON on the xmos board.

This is quite frustrating and the number of times i need to do this for the Xmos U8 board to come on seems to be increasing. But once its comes ON the Dac works without any problems.

I have tried changing the usb Cable , the power cable , nothing seems to fix this problem.

Is there a way this can be fixed ?

Thanks
GD

Im trying to find T/S parameters for the Vifa PL26WP05. Tried everywhere couldnt find it. Can anyone please share the datasheet if you have.

Anyone have a pic of the preamp board ?

Hi,

I'm playing around with LTspice and even with one singe opamp as buffer I get very large THD. anybody can point me to what I'm doing wrong ?

Harmonic Frequency Fourier Normalized Phase Normalized
Number [Hz] Component Component [degree] Phase [deg]
1 1.000e+03 4.894e+00 1.000e+00 0.18° 0.00°
2 2.000e+03 8.335e-05 1.703e-05 -153.42° -153.61°
3 3.000e+03 6.513e-02 1.331e-02 -165.32° -165.50°
4 4.000e+03 2.624e-05 5.362e-06 9.14° 8.96°
5 5.000e+03 3.068e-02 6.269e-03 6.51° 6.33°
6 6.000e+03 1.186e-04 2.424e-05 -8.84° -9.02°
7 7.000e+03 6.043e-03 1.235e-03 -29.63° -29.81°
8 8.000e+03 1.056e-04 2.157e-05 125.99° 125.81°
9 9.000e+03 4.735e-03 9.676e-04 -174.96° -175.14°
10 1.000e+04 2.753e-05 5.624e-06 -139.51° -139.70°
Total Harmonic Distortion: 1.479406%(1.515575%)

Almost finished rebuilding this amp, but cant get audio out of the left channel. Right channel seems to be fine. No left audio on U102 U103. No left audio on the crossover switch either.

Is there a schematic available for this amp?

I'm talking from the pleasure-seeking lizard brain side of me and not the practical or rational side.

If you could get a good deal on a F8 (closer to 3 than 4k), and you cared about enjoyment and the sound at a few watts, would you hesitate?

I have a new McIntosh MC275, and that is it's thing. I have a pair of 3-way Sonus Faber towers that can take everything that amp provides and way more (including a 200x2 McIntosh SS amp), but also have a pair of 4" FR driver speakers and very much interested in those, but also considering things like the Zu Dirty Weekends.

I live in a townhouse and cannot to nuclear on what I listen to. Anything over about 5 watts (if I go my the meters on the McIntosh SS amp) is starting to be loud and a little anti-social.

Or...would I be better off with a XA25...or would that be boring compared to the F8?

Thanks!

Hello all,

After enjoying a couple of years with Ian Canada's DAC stack, I thought I would build version 2. This would encompass using some of his new boards and use the StationPi as the platform. This is not a full evaluation of the sound, but rather a peek at some of the stages of my build using the new parts. I'm still listening to it on my bench, and have a couple more tweaks to finish it up.

A few notable differences from my first version are the addition of the new ConditionerPi, the FifoPi Q3, the StationPi, and the use of Ian's new LinearPI PSUs. To add to the versatility of the streamer, I also added the ReceiverPi for additional inputs - primarily Toslink. Oh, and of course the addition of a transformer output stage. Using a transformer output stage is a first for me, so will be interesting to compare the sound to my opamp output stage of my original.

Using the StationPi, the layout is less spread-out and more compact. The stackable PSU really helped gain back some chassis space too. I used 3 of them for the necessary 5.0 and 3.3v. Still had to use 2 xformers though, to get enough independent secondary windings. In addition, I did not need the +-15V PSU for the opamps of the Std I/V stage, so that helped with space as well. A cool feature of the LinearPis is they can be strapped for Master/Slave control. The external front-panel switch controls them all using this feature.

I put it all in the temporary chassis, so I could easily move it into my listening room and compare the sound using roon. The case is not up to my usual standards, but it's workable for the foreseeable future. Enjoy the pictures.

Note: Ian has some other new goodies supposedly to be revealed later this week.

In designing domestic sub-woofers we should be minded the cabinet has to fit somewhere, behind the sofa, under the bed etc . . .

If it's all about surface area and moving air 4 x 4inch subs should be as good a single 8. In practice they're not.

Why not?

Hello, I have this amplifier that does not turn on anymore, I opened it and I noticed that on the circuit connected to the power supply tray the 8-pin dual line integrated circuit signed U3 has exploded, the only letters I read are LN, it should be l switching power supply for standby, I kindly ask if anyone knows the exact abbreviation of this component, thank you.

I would like someone to guide me
I want to update the bat vk51se six pack of jensen 1uf 400v capacitors for something better and that sound better sonically since they are not available I have thought of Mundorf since they can be used by the measures and always oil.
Greetings

I just finished building my SV-EQ1616D All Purpose Phono Equalizer and wanted to share some photos.

I have lots of photos so I'll spread them across several posts. I'm no expert so I'm not suggesting that you follow my technique to build yours. I'm just sharing photos, good or bad technique and all.

I do welcome suggestions about improving my technique because I want to improve my skills since I have been bitten by the kit-building bug.

I wonder what the difference is between the Bride of Zen preamp and the Bride of Son of Zen preamp? The latter a balanced preamp?

Would anyone recommend the Bride? How does it sound basically?
Thanks.
😕

Any advice for an AD797 differential to single ended output stage with a gain of 9X for balanced voltage DAC?

I am planning to replace the DCX2496 output stage with AD797 opamp.
Any schema to have a gain of 9x and stable?
The dac is AK4393 with balanced voltage output

I have a signal generator which has good distortion performance but suffers from 50 Hz hum when measuring THD + Noise. With a 400 Hz filter the measured residual noise floor is much lower.


I think this is because it has a E-I power transformer in the case just cms from the oscillator and amplifier circuitry.

I want to relocate the transformer to outside the case and build a new regulator Pcb to go where it was.

The existing regulator circuitry is on the existing power amp board and can readily be bypassed.

The only issue is that the power supply is about 50v (unregulated) in and 37v (regulated) out which I believe is out of the range of a LM317/LT3045 type IC or. Jung type super regulator.

The generator, having a class AB power amplifier output stage, is best suited to a series regulator, rather than a shunt which suits constant current type device more, if I have that correct?

If that seems reasonable I would be grateful for recommendations on a IC or discrete low noise design for this project.


With thanks,

I'm using the drivers in my ATC SCM20 Pro PSL Mk2 studio monitors for a project. Most notably I'm making them active and lowering the crossover point for best power response and dispersion. I may need to make a new enclosure to reach the desired woofer q and the lower tweeter crossover point. The thought occurred to me: I have two Kef Kube 10b subwoofers which I bought to fill in the low end. I could integrate their drivers and amp in the new enclosure!
Originally my idea was to spend under $2,000 on subwoofers instead of another $15,000-$20,000 to move up the product line to the next best options: SCM50s or 100s (it seemed like the financially responsible thing to do lol). The SCM50s have a 9 inch woofer, the 100s have 12.

The Kef Kube 10b is a 10 inch sealed subwoofer. It's 300w RMS, low end -3db point of 24hz, maximum output 111dB, ~35L enclosure. Ideally I would have bought the next size up (12" with same amp), but they weren't in stock or on the same ~35% off sale. Their -3db point is 21hz and I assume they would move 50% more air or so. They'd have made the woofer in the monitors the limiting factor in all music genres, but whatever, can't have everything.

A problem I have is, the subwoofer's low pass filter is 4th order, and the sealed woofer roll-off is 2nd - they don't match. Lowering the sub's level a bit and moving it's crossover up a few Hz kind of compensates for this, but isn't ideal. If I'm going to put both systems in the same box, I want perfect integration.

Keeping fidelity and price in mind, what's the best way to fix this? I assume to extend the low end in the 35 liter enclosure, DSP of some kind is used. The driver will bottom out quite easily at some frequencies, so I think the included DSP isn't especially discriminating re: how much peak power it sends to the woofer at various frequencies. On the rear there are two pots and a switch. The switch is 0deg 180deg and "Corner". I think corner shelves the very low end from the mid 30hz range. Pot 1 is frequency from 40hz to 140hz, pot 2 is level. There's RCA and speaker level inputs. I prefer RCA because I get hum with some amps at speaker level.

I'm using all four channels of my RME Babyface Pro's interface as the woofer and tweeter preamp, so I'm wondering how I can make these subwoofers behave the way I want them to. I don't want to spend too much (the speakers and subs cost enough lol) - free is always best.

The woofer in the SCM20s is an underhung design and can move either 10 or 12mm without distorting (20mm gap and 8 or 10mm coil, not entirely sure). Its diameter is 5.4 inches if you include 1/3 of the surround on both sides. I just measured the resonant frequency of it in its 20 liter enclosure, and found it to be 53.5hz. The -6db point of the system is advertised to be 55hz (which to my ears is right). The datasheet for the woofer says its resonant frequency is 57hz though, so I'm a bit confused... Isn't the resonant frequency of a woofer in a sealed box supposed to be higher than it is on an infinite baffle? If it's 53.5 in the box, how low would it be in free air? Mid 40hz range?

For compatibility, below I used 10mm peak to peak linear travel and 5.1 inch diameters for the cone. Peak undistorted amplitude at different frequencies:

70hz - 95.0db
75hz - 96.5db
80hz - 97.5db
85hz - 98.5db
90hz - 99.5db
95hz - 100.5db
100hz - 101.5db

The natural rolloff starts at about 80hz.

The subwoofer's maximum output is said to be 111db. The woofer is high excursion, so I'll estimate xmax is 10mm, peak to peak: 20mm

62hz is the lowest frequency which 111db can be reached.
at 50hz 107db can be reached
at 40hz 103db can be reached
at 30hz 98db can be reached
at 20hz 91db can be reached

I was thinking of using the natural filter of the woofer in it's box for high pass. Reasons being: for ease of implementation and to maximize its contribution to the signal. There's obviously a difference in quality between the drivers and amplification (though I think a properly designed high current class d amp is more than good enough for bass). I think a midwoofer with the same motor as the one used in speakers costing as much as cars should be used as much as possible before switching. Unless the excursions would be severely mismatched. Do the frequencies and outputs above look like they'd work well together - well enough to put them into the same enclosure?

Hello,
I have just started designing subwoofer boxes (i did it before, but with random dimensions, sometimes I was successful, sometimes not so much).

Let`s get to the point...
How do I know when box is too big and will sound boomy? or perhaps when it`s to small and driver will struggle?

Currently I have 15l sealed box for my 10" 125W RMS sub.
It plays to high and after entering T/S and box volume into the program I get the graph that shows exactly what I was expecting (tuned to high) YELLOW LINE.

However I was playing with the box volume until I get it lower RED LINE. Yes I loosed the 3db gain (at around 90hz), but I can deal that. I rather turn the volume higher than listen to this loud 90hz bass and when it realy needs to hit (lower) there is no output at all.
But... the box should be at 100liters to achive this frequency response. Something is telling me that a 10" sub in that big sealed box will sound boomy.



How can I know when box is too big or small. What is warning me of exceeding the right volume?
Or is there any rule in general?

Should I go ported for this driver in order to lower the frequency?
Somewhere I read that round port shoud at at least in diameter 1/3 of the driver, what about square (L) port

And why does the bass response of 15l box YELLOW LINE act like it`s in ported box? I mean 3db boost in short range?

Thank you all for your time and help 🙂

Against OPA6112 or OPA6156 f.e.x.

Hi all,

I have a Gould J3B signal generator from the late 70s that I want to repair and restore as it has some very useful capabilities for audio work. It arrived looking good on the outside and grim on the inside and I can't get it past the "sort of half repaired" stage and would be grateful for some help chasing down the issues.

It has a Wein bridge oscillator in a shielded box and a power amplifier that can drive very low impedance loads directly, which makes woofer testing easy, as well as a 600 ohm balanced output transformer, for testing pro audio gear, as well as a square wave and auxiliary outputs for sync. In short it's perfect for what I want and there doesn't seem to be new equivalent available and so I'm quite keen to fix it.

Please find the service manual and schematic here: http://bee.mif.pg.gda.pl/ciasteczkowypotwor/Gould/gould.__j3b._._service_and_operating..pdf

It had a blown fuse and the power supply needed repair. I replaced the blown components and all the small capacitors as they were reading high and leaky.

The PCB for this is shared with the power amplifier and it appears that the power amplifier had been repaired at some point in the past and mismatched transistors used in the final outputs ( TR105&TR106). The service manual specifies 2N6179 & 2N6181 whereas this one has a BD237 & BD131 fitted. As I understand these parts are not equivalent and I have ordered MJE172/182 transistors as the closest I could find that is available new.

TR104 and TR108 were damaged and were replaced with NOS BC239 and BCY70 transistors.

The PCB then powered up and the test voltages were within spec. I set up the bias current through TR105&TR106 as per 5.6 (i) in the service manual and couldn't get the current quite high enough, even by turning the pot the whole way. In fact the pot didn't seem to have any sort of linear effect, it just seemed that at some point some bias current (~6 ma) would flow. I left this as it was, although the level specified was 18-30ma, and soldered the various wires ( to and from the oscillator as well as power, meter, outputs and grounds ) and with an ammeter between the test points I powered it up.

The bias shot up and the fuse blew again. After much swearing I checked everything over and powered it up again to find that now, for some reason, the biasing worked as per the manual and that everything seemed fine...

The problem is that now, when the output is turned up the output from the amplifier and the Wein bridge oscillator distort by oscillating like mad. This does not happen when the oscillator is isolated from the amplifier board.

Could the wrong output transistors cause this or have I damaged the oscillator somehow?

Bought the amp to get an education on SE 300B amps in general.. What an education to say the least lol... I may have come full circle, realizing the issue was actually written in English on my amp Right above the Din-E
110v !!!

In all fairness, I could not have known the original design was at the upper limit at 110V, with no elbow room for higher voltage...


At 120V, the extra 10V looks to be the issue for a 300B and B+ being WAY to high. Using the viariac and dialing to 110 (And even 100V) puts my load lines in a MUCH better place.... Hunting down a 120V to 110/100 V 500w transformer now...



In the meanwhile, I noticed my 175w light bulb current limiter droped the voltage from 120 to 100v, Whats the chances lol... Wondering what would be the downside of using a bulb to limit the voltage ?

I tried searching the forum and was surprised to get minimal hits.

What do you use for speaker cables in your DIY speaker builds, especially when shooting for the best possible sound (as opposed to keeping it low cost)?

Mine is an active system so will have a pair to tweeters, a pair to mids, and big woofers are less of a concern as they have the class-D amp attached onto the speaker stand so cable length is under two feet.

Right now I'm prototyping the speaker, experimenting, and speaker wires are temporarily regular PVC multistranded mono cable used for wiring the house and have two separate wires laying on the floor for each driver so inductance/capitance is likely a nightmare. Would like to get a sense of how you guys do it so to decide if I get a temporary improvement until I finish development and getting new amps, or go for the "final" cables before that.

Twisted pair, star quad with teflon insulation (such as VH Audio 4x18AWG), OCC copper/silver wire with teflon in any particular geometry, Kimber Kable 4TC or 8TC sold bulk (or other finished cable sold in bulk), or just use branded speaker cables?

If you DIY, how do you prioritize geometry vs conductor material vs insulation materials?

Thank you!

Hello, Forum members.

I am re-capping my IG-5218. The P/S board is finished. I had purchased qty 2, 250 uF/50 V Sprague capacitors (axial leads) to replace the 250 uF/35V caps used for C6 and C8 on the Wave Generator circuit board. I think I would rather use radial leaded caps now. I am having some difficulty finding 250 uF radial leaded caps. Can anyone tell me what the acceptable uF range is that can be used for C6/C8 replacements or do I need to stay at the 250 uF value. Thanks in advance.

Does anyone know what outputs belong in this amp ?

It looks like an audiopipe clone

With the increasing necessity for using surface mount components I was wondering if you could share some practical ways of handling them and soldering them? Also I'm not able to print PCBs so it's all perf-board or pad-board for me.

I did build myself a little alignment jig for transistors, but it's still like playing pick-up sticks with my butt cheeks:




To test them I use a cheapo multimeter that has an inline hFE socket and some bent lead wires wrapped around the transistor:



How do you even keep track of them? I have nightmares about losing my precious Toshiba BJTs.

This thread was a good start but didn't actually include much technique.
https://www.diyaudio.com/forums/solid-state/3240-smt-practical-diy.html

Thanks

Hi All.

Has anyone put two different Pass amps into one chassis with one shared PSU?

One channel from each amp would be mounted onto each heat sink, with the PSU switched between each amp so that I can use either amp, one at a time.

I have very large, and very tall heat sinks, on which I can easily mount two (maybe three) Pass PCBs per side.

I figure I'm almost certainly going to build more PASS amps in the future, so why not save on buying another chassis and PSU when these two expensive elements can be shared between two (three?) amps?

I have attached a photo of the chassis minus the front plate, and one of an Aleph J board lying on the heatsink for scale.

If anyone has done this, I would love to see some photos, and hear any comments you might have.

Also, if you were me, what amp would you put in with the Aleph J, and why would you choose that amp?

I'm looking for a bit of know how on metering SPL at gigs. I currently have a basic portable meter but we are looking for a system where we can have microphones at various points above the crowd (preferably wireless and battery powered) with readout screens with long and short term averages on screens at the mixing desk (in dBA and dBC). Is there anything commercially available like this?

This thread is only for the discussion of passive crossovers, active that can be implemented
as passive or to explain some theory is fine but otherwise start another thread about them.

There have been several studies on the audibility of the phase distortions typically found
in multi-way loudspeakers that usually find, in typical reverberant home rooms they are
not audible. Most studies state that the distortions are not audible. One study found
that simple transient sounds such as banging blocks through headphones exhibited a
minor changer in timbre. It's probably been 20 years since I read these and I'll try to find
a list of references - I posted them on the Bass List in the mid 1990s. Here is one:
Lipshitz, Stanly P., Pocock, Mark, and Vanderkooy, John, "On the Audibility of Midrange Phase Distortion in Audio Systems,' J. Audio Eng. Soc., Vol. 30, No, 9, Sept. 1982, pp 580-595.
See also:
Audibility of Phase Distortion

Please start a new thread for further discussion on phase audibility - not here.

I'm interested in passive solutions that provide linear phase simply to understand the methods
and theory.

I've followed the literature closely from about the mid 1970s to 2000, less so since then,
The obvious solution is first order but they have many disadvantages. Then we had filler
driver solutions that I mentioned many years ago in this thread:
https://www.diyaudio.com/forums/multi-way/71824-square-waves-4.html#post6074371

"A Novel Approach to Linear Phase Loudspeakers Using Passive Crossover Networks" Erik Baekgaard May 1977

I thought that this was invented by Baekgaard but then found this reference to a 1967
paper: Kido-Yamanaka crossover was first described by Bunkichi Yamanaka of Matsushita Corp. (Panasonic) in 1967.
A Unique Loudspeaker Crossover Design with Waveform Fidelity

Most simple 1st order systems have horrible off axis response.

Another approximate solution was proposed by John Bau and released as a commercial
product, the SPICA TC-50, in 1983. Bau states that he started with a 2nd order Bessel low-pass
and then found that a first order high pass with delay led to an approximate linear phase
result. This site offers a lot of info but not on the theory:
Spica TC-50 Product Information, The Spica Speaker Enthustiast

I have owned these speakers and they have very poor off axis response. This type of
solution would benefit greatly from coincident drivers.


Jeff B. hints at a third order solution with overlap, also as an approximate
solution in this thread at the PE Tech Talk Forum:
Third Order Transient Perfect Passive Crossover -

Techtalk Speaker Building, Audio, Video Discussion Forum

No design equations are provided and I've not seen polar plots for the off axis response.

DDF claims here that he has been promoting this type of solution since the mid 1990s
but he also has not provided design equations:
Third Order Transient Perfect Passive Crossover -

Techtalk Speaker Building, Audio, Video Discussion Forum

DDF makes this comment that might offer a bit more insight:
It sounds like Jeff locked onto a crossover target I know I locked into myself a long time
ago (and as did George Short at North Creek) as the best compromise for most system designs, and one I've tried to socialize over the years:
- sloped baffle
- soft knee thirds with staggered xover frequencies and mini-ripple response through xover

Benefits:
- flat response on axis through xover, but one easily tuned if a slight dip or bump is desired
- high out of band attenuation
- low complexity and parts count
- soft knees reduce tweeter "flare" off axis and provide better driver integration
- sloped baffle allows the power response to more closely mimic the on axis through xover
- low GD variation over frequency
- it sounds bloody good!

DDF suggests that his design is the same as Jeff B's but I read soft knee 3rd order for DDF
and overlapped 3rd order for Jeff B.
Jeff B. confirms the above where he writes:
"Then your crossover and mine are quite different afterall. John was correct when he speculated that I followed a similar path to his QTP 2nd Order filter. What I did doesn't match what you have described above though. "

And also (I don't know who Vance is) post #113:
"You described Vance's spread 3rd order as an example which results in two different Fc values that further separate the lowpass and highpass sections resulting in a more in-phase -6dB crossover point; something like a Linkwitz-Riley response with ripple. Mine on the other hand goes in the opposite direction where the lowpass and highpass are not spread but overlapped with each other, then the transfer functions are modified so that they sum to a flat response. The overlap creates the minimum phase summation."

Neither has provided design equations so I'm not sure about this if anyone can provide
them that would be helpful. I could experiment in the simulator but equations would be better.

John K. Wrote about a QTP second order network here that is on the Wayback machine:
http://web.archive.org/web/20050222114023/http://www.geocities.com/kreskovs/Quasi-transientP.html

Am trying to compute power out put of amp.

dumping power into 8ohms

using 440hz sine

example voltage; amp at +5db

peak/peak 55v (2ch powered)
rms 20v (2ch powered)

I imagine I use RMS voltage for calculation; so 50 watts? Is that right

am now thinking that makes sense, is a 100w / ch amp. and the volume prob goes up another 5db (presumably)

Does anyone know anything about the Wadia Swift Current I/V converter? I will try to look up any patent information. The following is a quoted directly from their site:

Conventional digital-to-analog converters perform current-to-voltage (I/V) conversion using feedback circuits based on operational amplifiers. Because the signal from the DAC chip consists of a series of step changes, the distortion introduced by this feedback circuit is a significant limitation on sonic performance. In contrast, the Swift Current circuit performs this I/V conversion with Wadia’s patented current-conveyor integrated circuit (IC) that eliminates feedback. This bipolar IC consists of an innovative connection of Wilson current mirrors, an emitter degeneration compensation scheme to optimize transient response and stability, and a novel current mirror arrangement to enhance output impedance.

Click to expand...

So there is a buzzing / humming sound on the right channel of the amp which stays constant with volume changes and can be "heard over music playing"
The cables are all connected properly and the power source is clean.

I would appreciated debugging steps !

thank you

Hi all,

I have some old Mission 734 speakers but but the tweeters have failed. I was looking for get some replacement. But I'm looking at around £40-50 for each tweeter. Is that good value for an older set like this.

Most of the tweeters available on eBay are for the 734i version of the speakers. They are the same size but I assume to be a different spec. Would those work ok?

I currently have a Mission 734 set and a Mission 75c centre

I was offered a set of Q acoustics 2020i's (5.1 with a 2070 sub) for £230. Just not sure whether to fix what I have or move on.

Any input would be nice

Hi,

I want to make a circuit that can take a simple 10-15V DC input and give me a multiple clean regulated 12V DC outputs. I want the output's to be isolated from the input and from each other to stop interference. The output's would only need to supply about 2-4 amps each maximum. That's the idea I have in my head anyway. I'm an electronics novice so I don't know how much of this is possible.

This is to supply power to several pieces of Hi-Fi equipment that require 12V DC supplies.

Could anyone point me in the direction of a suitable design for this?

May thanks,

David.

I'm building 2.1 system with 3 separate but identical power amp circuits. For preamps, I have ne5532 board for stereo preamp in inverting configuration. Bass board has low pass filter built but I don't yet know if it is also inverted.

In case it is non-inverting configuration, can I, and should I just reverse bass speaker polarity, or leave it as is and reverse stereo speakers polarity? Trying to make sure it is all in the phase in the mix. Thanks.

Hey all. I know I'm late to the party but I am just getting into the whole DIY DML panel speaker scene. I am wondering about how viable they are for Atmos. I have a lot of questions and I am not seeing many people doing this and I'm not sure if it's because there is good reasoning behind it or if it's just not a "thing" yet. I'd rather not be the Guinea Pig if it's a flawed concept.

I am currently running a reflective 9.1 (5.1.4) system using a Marantz SR6011, 4 Pioneer Elite Andrew Jones SP-EBS73s, an SP-C22 with the Philharmonic driver/crossover upgrade, and a Monolith THX 10. It's a good system, especially for the cost but I like the idea of being able to get all the speaker stands off the floors in the room, make the speakers disappear more-or-less, plus having that big wall of sound in my space (~2600 ft^3, carpet and drywall, square-ish) would be nice as well. It would be an inexpensive endeavor and only relatively labor intensive (by my standards), plus it's just cool. People rave about the fidelity for such simple drivers as well. (I'm going to build a couple next week for grins and to see how I feel about the SQ).

I guess my main concern is the diffuse nature of DMLs. It has its benefits but when you're dealing with object based audio would the sound be too diffused to render the 3d landscape properly, especially for the height channels? Would it make more sense to just use DMLs for the FL/FR/LS/RS and use traditional ceiling or reflective speakers for LFH/RFH/LRH/RRH? Or would the 2 speaker types not blend well? (I would probably keep the center channel as-is since it lives on my console and isn't taking up space or harming the asthetic.)

Also since the exciters used in DMLs have such low power ratings (20-40 WRMS @4ohms) due to the efficiency of the panels would I have to worry about nuking them at ~220 WRMS? I can use the Audessey DSP to trim/boost individual channels so with proper setup I would probably be fine, right?

Thanks in advance!

Have you a YouTube posted video of your solid state amplifier?
Post here.
Here is my latest short video. Mosfet Amplifier SA2015 - YouTube

Hi Guys,

This amp is from the 80s I think. What do they sound like ? Pretty old so not great ?

Thanks.

Hi folks

During the late 80s before the Japanese economic bubble burst, all the big electronic corporations were putting huge sums into R&D of their digital products and JVC was no exception, which lead to the development of their own series of DACs using a technique they developed called Pulse Edge Modulation. There weren't many DAC chips in the series, the first was the JCE4501, then the JCE4302, then the MN3550x series.

There is precious little information available about these DACs, mostly it is to be found in the service manuals of their CD players. I've compiled what info I could glean:

In the early '90s JVC developed a proprietary circuit for a more accurate D/A conversion, called P.E.M. (Pulse Edge Modulation, in contrast with the common PWM, Pulse Width Modulation) which gave a big "plus" to their CD players so that even the most die-hard audiophiles had to recognize those machines played extremely good noises.
In particular, that circuit allowed the JVC CD players to reach the limit of the maximum theoretical CD digital resolution, approaching 15.9 dB (theoretical max being 16 dB).

1993 JVC company developed A high-quality bit compression technology called K2 super encoding; (that is, today's XRCD, you can check it out)

JVC company developed a 20-bit K2 processing technology for the main purpose of the player in 1994. The purpose is The 16-bit data is converted into 20 bits, so that the reproduced sound is close to the original sound, and high sound quality is realized.

http://www.jvc.com.cn/woodcone/k2.html

P.E.M. D.D. Converter with VANS, fine pulse interface

JCE4501 – JVC bitstream DAC

JVC K2 Interface, a circuit that reduces jitter by resampling the pulses with a short-duration gate just ahead of the single-bit JVC JCE-4501 DAC chip.

K2 technology is used in front of the digital filter


JVC D2000 DVD player uses K2 with JCE8001 – last K2 chip produced

JCE4302a is a DAC with 8 times filtering inside. JCE4301a doesn’t. It must be preceded by one. For example, ym3414 filter chip, JCE4300 is a pure K2 processing chip. Filter chip, without any 4 times 8 times filter. Just pure K2 processing

The DD (Digital Direct) converter is carried in the D / A conversion part.
In the DD converter, the digital signal is converted into a 1-bit operation pulse wave that changes based on the crystal clock, and is directly converted to analog. Therefore, unlike the conventional ladder type D / A converter, since the bit amount is not piled up, zero cross distortion due to the amplitude error does not occur in principle, and the reproduction ability of a minute level is greatly improved. Furthermore, the excellent characteristics of a dynamic range of 100 dB or more and a distortion rate of 0.0017% or less are realized.
The DD converter consists of three parts: digital filter + noise shaper + PEM / DAC, all of which are digitally processed.

I am revisiting this amplifier of which was my second FW diy project. I say revisiting because I removed the boards years ago to install other boards. I have since found that the j-fets I purchased before the LSK ones became available were fake and I have not heard this amplifier as it should. Another reason is I recently built the F4 and am amazed with the sound it produces which is almost if not the BA-2 amplifier with less output devices. Now I want to rebuild the SE version of the Burning Amp series. I decided to remove the IRFP 240 mosfets I originally installed and buy a tube of 25 and match them better since I like to think I have more experience now building FW amplifiers. I managed to get 15 to .1V tolerance out of the 25. I am using just one set of boards from our store to make a stereo amplifier using 6 output devices instead of 12 but now both boards will have output mosfets that match each other so that if I desire at a later date to build another complete SE BA-1 and have mono's. It would require a massive case to build the BA-1 as described in the article so to me if is more practical to build this project in mono configuration. Right now I am going to build a stereo version using 6 output mosfets per channel.

My personal opinion is that the BA-1 and BA-2 designs are diy projects that may be compared to some of the Passlab designs especially if one builds either with 12 mosfets per channel. At least some of the older Passlab amplifiers.

Hi All,

Wanting to buy one Acoustat transformer model number tta-246b for the 2146 interface, suits all Spectra 44/66/4400/6600 loudspeakers.

*Will pay good money for it, please let me know if you have one.

Thanks,

Steve.

Hi all,

I've got the JDG Model 1 Power amp. The default setting of the gain is 26dB. I found that it possible change the gain with the switch or something under the Modules. But I dont have the service manual or guide to tell me how can change it correctly! I would like to ask for the help to someone have the info or experience of that....! Thanks!

Regards,
Hatasa

Its been a while since I was able to be here. Greetings all, I hope you are all well..

Yup, I'm going to build a couple of these. My last build was more challenging, this one should be easy, however I want them to sound intimidating and reasonably good as well as look it. After all I could probably make my refrigerator sound better using it as a cabinet. Yeah I,m bored. too much time to waste..🙂

I have a few ideas as to how to hide the drivers, down firing 12" in the skirt, isobarik mids in the neck, tweet on the eye stalk ..Yeah its goofy and weird, but. If anyone can suggest a way to make em more wacky than they already will be, maybe suggest driver layout and config. I'm all ears...

And no I am not insane, or off my meds...🙂. I just need to do something different...

Over the now fully subscribed F5X Power Amp Final GB thread, we have been asked about the preamp as well.
https://www.diyaudio.com/forums/pass-labs/225230-f5x-preamp.html

Just to allow us to gauge interest and see how we have to prepare, you can start subscribing here.
We cannot promise to support unlimited numbers obviously.
And it will not be a budget project.
So please only put your name down if your interest is serious.
And each person is limited to 1 set.

The cases will be supplied by the same source as the power amp, and is from the EU.
It is a 2-case design (amp & PSU), and you should be prepared for 700~800€ just for the cases.
The DAO case made also in the EU was ~400€.
Perfection has its price, and I know how much effort went into that one.
https://www.diyaudio.com/forums/hea...s-zgf-headphone-amplifier-34.html#post5552941

We shall try our best to make it happen, some time in 2019.


Patrick

would the attached be classed as low leakage, or would it need to be less.


i have a couple of 1uf caps in an amp im working on that are below the threshold of what is stated in the spec(reading around 0.25uf) and need to replace them.
the drawing denotes them as low leakage, so i need to know if these would be suitable


just as a note what would be classed as low leakage for my future reference many thanks

Since my last build a few years ago Hammond has released some new power transformers targetting the guitar crowd.

I'd not seen the 290 series previously and I wonder if any of the esteemed members has experience with these and has compared them to the 300 series.

There are some models (e.g. the 290CEX) that offer me some advantages in my yet to build amplifier. The power supply is in the last stage of collecting parts.

Tube Guitar Amplifier - Power Transformers (290 Series) - Hammond Mfg.

Thanks in advance if you share your experience / thoughts.

AM

Greetings all,

I had acquired the wave-guide in the title line and I rather like it with Beyma 380M. Thus, I was wondering, if it could became a good basis for Unity/MEH by extending it.

Design of the extension could be done using Marcel's ATH4 program. However, to use the program, I one would need to find the shape of the expansion curves of the current wave-guide along the x and y axes.

Would anyone have an idea how to do that with a reasonable degree of accuracy?

Kindest regards,

M

Looking for a Pentode wired El84 amplifier design. I have 2 5k opt and a small 200v power transformer i want to use in a little cool project. Is there any good schematics out there? 🙂

2SK182E SOLD

I have 4 roughly matched 2SK182E that I purchased from Watanabe, will let them go for 120.00 per set of 2.
Shipping CONUS only

I figure this is a good spot as any for this question; I imagine it is VERY simple straight forward.

I have twelve 8ohm 100w resistors.

I want 8ohms resistance, but higher power dispersion capability.

Seems the only combination is a 2s2p combination and that would yield 8ohm, 400w.

Am I using the math correctly? The part am least sure of is the power dispersion capabilities being independent of the circuit. i.e. if the circuit has 400watts of resistors, that is the max it will disperse.

getting more specific; with a 2s2p resistor set up, does polarity start to come into play with respect to power dispersion?

with the resistor value I have (8ohm 100w), is 2s2p with negative connected to the 2p side mean the Max power dispersion is 200w / 400w or still just 100w?

Translated From Mr Makoto Ohashi's forum


World Premiere - Western Electric WE300B/2021 Lot REPORT #1

In 2006, the Western Electric 300B was discontinued without any notice although manufacturing announcements were repeated on the WE homepage,
no one even saw the actual product in the United States, and gradually the people concerned said that it would be difficult to revive even in the meantime,
and it had been 15 years since the production was discontinued.

That is the complete announcement. I contacted the site immediately and confirmed that it was true, it seemed to be true this time. So I immediately placed an order.
The reason is electrical measurement and sound quality confirmation. For that purpose, 2 valves are not enough, so I decided to purchase a matched quad (4 valves).
The local price is US $ 3099. If you add tariffs and shipping costs, it's a lot of money, but that's not the case.
When it comes to the revival of the original Western, I have to get it anyway ... I felt like that sense of mission.

What appeared in front of me after unpacking it ...


There is no different from 15 years ago. This is the best of the original Western Electric.


There is no different from 15 years ago. This is the best of the original Western Electric.

In the box, the instruction manual, measurement data with serial number, and warranty registration card are stored as they were in 2006.

The most important measurement data sheet. The method of measuring the Ip value at Ep = 300V and EG = -58V is the same as at that time.


Each part in the valve has not been changed from the original. The thinness of the glass remains the same as it was at that time.
The pitch of the sound when the glass clicked with the index finger is also unique to the WE300B.


Print of the base part. The miracle of date code 2113 (first quarter of 2021) will be handed down forever.


The appearance of the rice ball-shaped mica, including the filament hook shape, has not changed at all.




This is the serial number stamped on the base. The new lot starts at 3.
It can be said that the product is complete only when these three numbers, the outer box, the data sheet, and the engraved base, are complete.

So far, it's perfect, it's better than expected. But my biggest purpose today is from here. How does the electrical characteristics compare to the conventional original WE300B?
…about it. For that purpose, a helper was called in a hurry. We decided to have Mr. S, who is asking us to assemble our amplifier,
come to the showroom and perform precise measurements. Is the objectivity of the attached data sheet guaranteed?



This is a device that records the dynamic characteristics of a vacuum tube by swinging the plate voltage and grid bias.
All control and data management is done on the computer.
Is it easy to understand the device for measuring the Ep-Ip curve that is often found on vacuum tube data sheets?
Is the wonderful Ep-Ip characteristic attached to the reissue WE300B ?


The data sheet attached to the product is on the left. The data on the right is the data measured in kind today.
First of all, I tried to collect data on individuals in the first quarter of 2006.
Although there was a 2-3% difference that seemed to be environment-dependent when compared,
the same difference was observed at almost all points, indicating that the reliability of the measurement results is extremely high.

Finally, when I take the data of this lot ...




Plate current: 56.93 mA, internal resistance: 800 Ω, transconductance: 4891 μm hos, μ: 3.9 V / V


Plate current: 56.41 mA, internal resistance: 820 Ω, transconductance: 4753 μm hos, μ: 3.9 V / V

Data log was detected. It is a unique value to the head family, which is completely impeccable.
First of all, I was very satisfied with the fact that the electrically incorrect one was reprinted.
Let's check the sound quality before checking whether it can be said that the price is about twice as high as it was in 2006.



Change the place to the listening room and burn in 300B first. After getting used to it until tomorrow morning,
I plan to take the time to listen to the comparison. Please stage tuned the second report (listening)!

I got a Peavey Classic 30, put new tubes in and 1 does not light up, a power tube, the last one in the chain. Does this mean I have a bad socket? Yes I tried other tubes in there with same result. Is it ok to use unmatched tubes? or to mix different manufacturers?

Hello everyone,

I have a Crate GFX-212T (120W) combo amplifier that I would like to run into headphones to practice with.

The Crate combo amp is spec'd to drive a 4Ω load and does in fact drive two 8Ω speakers in parallel. There is an external speaker output per the attached manual and schematic that is wired in series. Essentially, I would like to disconnect the speakers and use the external speaker output signal through a cabinet simulator circuit with a headphone output. The headphones I have are 47Ω.

The cabinet simulator circuit I was looking at building is the "With headphone output" version located at the following address:
Speaker simulator based on Marshall JMP1


If I want to use the external speaker jack on the Crate amp while also bypassing/disconnecting the internal speakers, I would have potentially 120W at 4Ω at the external speaker output. To what level and how can I knock the power level down so it could safely feed into the cabinet simulator circuit at the link above, with also not damaging the amplifier (if it even would damage it)? Would it be wiser to put a resistive load in place of the internal speakers and something else to decrease the signal before heading into a cabinet simulator circuit?

I will probably have follow-up questions as I'm new to DIYaudio, and also thank you in advance for the advice. It is much appreciated.

It is a big module rater than a chip really . Used by Audio Aero , Audiomeca , Nagra , Camelot , Talk Electronics and handful of other manufacturers in the beginning of the century. I know there are two of those modules on the big site. Both in Russia, both earlier MK I and both priced to attract buyers form United Emirates .I know there must be a supply of MKI versions since a lot of buyers of those early machines upgraded to MKII chip when it appeared. I'm interested in either version. TIA , L

Ive heard that mosfets produce a better sound in amps is this true? do they work on the same principle?

I have a TU-8200R that I have put together with kind assistance from Victor, who has been awesome to deal with. Victor pointed out that at p.19 of the manual there is chart with reference voltages that can be checked. I am careful and this is new to me, so I want to be sure I know what to do.

I found the points in the circuit board, and see, for example, that the first row says 1,2 3.2-3.7v. Is this DC or AC? (I presume DC but am not sure). Do I measure voltage between points 1 and 2, or do I measure each of them to ground?

Any clarification on this would be appreciated. The amp appears to be working well, and sounds beautiful.

TIA.

Hi Evryone,

On my workbench I have an old Ming-Da MC3008-AB brought to me for restoration after being in storage for 10+ years.
It had a broken 805 tube and all the capacitors were bulging.

So I replaced all the caps and tubes but unfortunately there is an annoying hum coming from the speakers and audible physically.
As you can see on the schematic the A+ filter caps are only 330uF instead of 1000uF. I added 470uF the the first set of four caps but this didn't improve anything.
Also, lowering or removing the NFB makes the hum louder. I've also added balacepots to the filaments of the 300B and 805 tubes but no effect. I adjusted the bias-current for the 805 at around 100mA.

Could it be that the transformers are causing the hum? Or any other suggestions?

If my preamp has 5 watts of output and I run it into a 100 watt amp, will the 100 watt amp produce more wattage?

I have a couple setups like this but they have always run safely. I can't really say I notice a volume increase with these high output preamp setups but they surely sound fuller on the speaker end of it all.

Hi,

This is split from a thread in Instruments and Amplifiers. I was hoping to get more suggestions on a particular aspect of a guitar amp build. Delete if not allowed.

I've been designing and building a guitar amp over the past few months and I've already completed the power amp and am currently working on the preamp. The power amp is totally silent, no hiss/hum or anything like that. However, I'm getting a fair amount of hiss from the preamp. When the master volume is turned up full (as you may do if you want a very clean sound) there is an unacceptable level of HF hiss.

I have attached the schematic in case anyone has any suggestions on how to improve it, or if I've missed out something obvious.

The hiss seems to be generated by U3.1 as grounding the input to U4.1 removes the problem.

Any suggestions would be greatly appreciated.

Thanks,
James

Hi everyone,

I was wondering if I could get some help with an issue I'm having with a chipamp build.

I built it using the TDA2050 snubberized power supply:

It hums, a lot. It has a very loud 100hz hum (I'm in the UK).

I have played around with a cheap digital scope I have, and it seems like the issue is with the +ve supply, which has 1.5v of a sawtooth 100hz signal in it. It's also slightly lower in voltage output (~20v compared to -25v -ve, which is what I expected).



This signal is exactly mirrored on the output too.

On the -ve, there is the same signal, but only around 25-30mv:



Interestingly (maybe), the mirrored signal on the output disappears if I touch the audio input. If I touch the audio in on the right channel, the right sawtooth output signal disappears at the right speaker terminal, but it remains on the left. If I touch the left in, it disappears on the left out but not the right.

I've tried moving the wires around, changing ground positions, moving the transformer, no change. The rectifier tests OK.

The only thing I haven't done is change the 10,000uf cap on the +ve rail, which I'm going to do today. It was a brand new Nichicon cap, does it seem possible that this is the problem and it's just not getting smoothed?

It seems like something else might be going on.

Got several mtx 1501d amps in (old design) that a fellow before me tried his hand at fixing. This one in particular I got the power supply running however i cannot get to output side to oscillate and the board mounted 42n20 mosfet (its entire drain pad is soldered to the board) gets quite hot with even a short power up of about 2 to 3 seconds. What is that mosfet's purpose?

(If it is any help, I currently have one 1 42n20 in the high side output bank and 1 in the lowside output bank. Led 399 illuminates (and of course 436 does as well) but led 238 does not. The previous person also replaced diode d199 and there are char marks around that SMD component.)


Thanks in advance
Steve

After reading about the SE KT120 car audio amp kit here and the tube SMPS thread here, I thought I would reach out the the developer of the amplifier. I was curious to see if he was interested in developing a stand alone SMPS for tube amplifiers. It turns out that he has done some work on such a design but he plan on having it run off of 13.8V, for car use. He is also looking for some input as to the design itself. Would you guys like to add some input?

I will post our correspondence below.

I have 2 questions. I was wondering if you will be releasing a stand alone SMPS for tube amps that runs off of 12V? There are few people on diyaudio that would be interested in one. I was also wondering if you will be making a 120V of the monobocks? Any chance it would be easy to modify the PCB to work of 120V?

Click to expand...

I have a standalone power supply in the works. For the most part it’s the same one that I use in the monoblock. I’m having trouble making a few decisions or I would already be producing them. My dilemma is I’m fairly confident I can come up with a design that produces over 250w but I’m not sure if that much power is really necessary. I’m also on the fence about whether to include a heater voltage supply on the standalone unit. Start a thread and see what people want. If there’s enough interest I will make it. Send me back a link so I can follow along.

I don’t have a 120v solution yet but I’ve been using and suggesting this:
25A 14v DC Power Supply for Chargers (350W)

It runs 2 kt88 monoblocks nicely. It should run 2 kt150’s but I suggest using separate supply’s for that application. The monoblock draws about 8a with an el34 and about 12a with a kt150. The 120v question comes up a lot so I have been putting thought into a 24v version. This will reduce current significantly and make it easier to run on 120v. I’m thinking I can modify my existing design by changing the windings on my transformer to accomplish this. I also plan to make a 120v monoblock at some point. Finding time for all this is the biggest problem.

Click to expand...

Would you mind if I used your response in the topic? I don't mind starting one and seeing what interest is out there. I do know that guys on the site are going to want to know more about the design than just the voltages and current abilities. Output impedance, switching frequency, noise, etc. are all things they are going to be interested in. Do you have some of that info available?

Click to expand...

You can post my responses. Switching frequency is 60k/2, quesent current is 280ma, efficiency is 84% @50w – 87%@100w and 92%@150w. Output regulation is 4% under 100w. I don’t have a measurement for over 100w. noise is 2.5mvrms. When I designed the power supply I added output capacitance until there was no measurable ripple across my speaker load then used a small filter in the pre section but none is required in the power section. The monoblock I make is dead quite.

Click to expand...

I retrieved this fender rumble 25 PR499 from the "not working bin". According to the schematic it employs a TDA1514A at the O/P stage. This one had a LM3876T. Is this correct?

I have a Crate VC508 guitar amplifier that many recommend modding by replacing the TL072CP opamp chip. I got a TI NE5532 off ebay. It's supposed to be a stright up replacement but it's about a third of the size. The TL072 is around a half inch rectangle with 8 legs going into a socket. The NE5532 also has 8 legs but is less than half the size. I need a low noise drop-in replacement for the TL072CP (I broke one of the legs removing the original). Any suggestions?

Will the Z44’s with 100 ohm gate resistors work in this amp ?

Awesome tester, but it was a bit of an impulse buy and I'm realizing I just don't have as much of a use for it as I thought.

$700 shipped, or local pickup in the RTP area of NC.

https://i.imgur.com/yxJZgDv.jpg

https://i.imgur.com/XEnHoxx.jpg

https://i.imgur.com/OFp4uet.jpg

I want to report that Victor has been great with getting the 8600S with all upgrades to me. Because I have neither the skills or tools to put it together I asked to pay for assembly. Victor put me in touch with @xsiliconkid who only lives a couple of hour away, who could assemble the kit for me. I also got a nice friendship during the process as well!

I'm at about 60 hours of burn in and loving the quietness and warmth of sound already. Cossor 300B, Gold Lion 12AX7 Genalex, the 2 smaller ones are BVA. The highs have seem a little rounded off right to me. Maybe it's the warmth or these particular tubes will get better high detail after burn in? It maybe that I'm also used to my solid-state Schiit Rag1? The Clears are known to be warm also, so that's not the ideal synergy perhaps? My only means of comparison at the moment is my Focal Clear headphones and UM Mest OG iems. The Mest iems are extraordinary in the high detail retrieval without being harsh, so that's a better combination at the moment. But I think the highs are better now on the amp on day 3. My Focal speakers are the active xlr fed Solo6, so I can't use the amp there. I'm shopping now for passive efficient speakers, but want to finish burn-in so that I can see if the high detail emerges more.


Oh I remember that I also have ThieAudio planars which have generally been a little bright for my taste. At least for the the current state of burn-in, they are now only slightly bright. Patience....


But kudos both to Victor and Graham. Graham was patient with my mistakenly feeding the amp with my Schiit Freya+ preamp and with the volume low, so I even set the headphone gain jumper at 3, instead of 2, before I discovered the mistake! Such a pleasure to get to hear this amp! So quiet even with iems.

I have two Audax TW034 drivers and Waveguides to go with them. New never used. Asking $180.00 for all. Continental U.S. only.

I found a schematic for a LM833 on the data sheet and I labeled all the components. I have been looking for the schematic of an op-amp to try to build out of discrete transistors to see how that works, especially because it might be useful to try to build it from 2N5551/2N5401 to increase the voltage range of the amplifier. I would have to decrease the quiescent currents so this might reduce the slew rate however, but it might still be interesting to try.



First of all, does this look like a good design to start with? I looked at the NE5532 schematic but it required multiple emitter and multiple collector transistors which I think are going to be hard to get, or match parts to provide work-alikes.



Is the P MOSFET or P JFET (Q2) I think is there to ensure that Q1 turns on when the chip is powered on?


It looks like C2 is a compensation capacitor for unity gain stability perhaps?


Is it possible to get performance from a discrete design that is comparable to the IC version, or are the matched components in the manufactured chip required to get low values of offset and distortion?

I let a friend listen to my Modulus 86,he is now recovering from the shock and would like to know if someone has a 686 for sale in Europe. TIA

I've built the (LJM) L12-2 amps, sounds fantastic, however I want to incorporate Lt and Rt volume/gain control. There is a lot of info in these forums and I found one I like and think will work. Its from Parts Express. Buffered Volume Control -

Techtalk Speaker Building, Audio, Video Discussion Forum.

I'm no engineer but I do know that layout of traces and components on a PCB board is important.

I need some opinions if the layout I did is going to work before I burn the PCB.

Thanks much🙂

Hi guys,


I am planning an open baffle speaker with a 15" BMS woofer, a 18s nmba520 10" mid and the 18s nds1095 CD with XT1086 horn.


The Baffle for the 15" will be a U-frame to be determined. The one for the mid is supposed to be as small as possible.


I wondered now if the speaker could potentially profit from a second mid driver in a MTM configuration. With a crossover at 1400hz a tweeter woofer distance of 23cm is advised which seems doable with the 10" and size of the horn. I am not too familiar with MTM designs and well, speaker design in general so is that a stupid idea? What are your thoughts?



I ordered the parts a little prematurely a few weeks ago so that is nothing to be discussed. I could only order a second nmba520.


Thanks!