Hello

I´m from Brazil and here we dont have access to very good speakers for home use, here we only have manufacturer for car speakers wich are not good for enclosures...

we have to import the good speakers, but with the dollar exchange rate for 5:1, even cheap speakers become very expensive for us, and we have the import taxes and shipping costs high too

so i bought a pair of dayton audio ps95-8 3-1/2" Point Source Full-Range Driver from a friend who buy when he went to USA, and now i am thinking what i could do with them

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Question 1: Is dayton audio ps95-8 3-1/2" Point Source Full-Range Driver good for the Frugal horn?

i love the concept and think that a horn will make this speaker sound better and with more bass than a bass reflex box...

am i right?

if i´m not, wich enclosure could i build to get the most of this speaker (in terms of bass and in general)

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Question 2: will i need a subwoofer to use with them? the frugal horn alone will lack bass?

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https://www.daytonaudio.com/product/1241/ps95-8-3-1-2-point-source-full-range-driver-8-ohm

Hello hello!

I hope I'm not asking too many questions on this site! I have tried to reciprocate and answer questions whenever I can, but since I am a newbie it's not often that I feel I can be useful! Invariably I get kind and helpful answers, and I do not take that for granted! What a wonderful community 🙂

Anyways, to my question:

I have spent some time fiddling around with various simulation softwares. I think I've gotten a hang of the basics of WinISD, I understand at least how to basically navigate the late Mr. Bagby's (RIP) PCD, and this week I have started trying to learn the interface and tools available on VituixCAD, which I am expecting to become my one stop shop once I get more comfortable with it. Someday, I hope to learn how to use AKABAK, but one thing at a time.. haha

If I went into detail about everything I DON'T know about crossover design, I (and possibly the more patient among you) would be here all day, so for now my query regards phase and time alignment.

It seems to me that variable time arrival throughout the frequency spectrum is inevitable? So, presupposing that, we have to decide between coherence at the crossover point or a short group delay across the whole spectrum?

My (correct me if I'm wrong) understanding is that, to slightly misuse an economics term here, it is basically a pareto efficient system where you cannot improve coherence at crossover point without worsening average group delay?

I read an article that went into how different passive electrical filters shift phase above or below your crossover point depending on LPF or HPF, and how the common approach is simply to use a high order filter to minimize the range of crosstalk between drivers, then to focus on a good average group delay. But then, I have also come across folks that seem to pay paramount attention to coherence at crossover point, who say that phase shifting is undetectable at high frequencies so it's ok if it's a full 180 DEGREES OUT OF PHASE with the lower region??

As a rather gullible newbie, I am begging to take someone's word on this! But my research has given me a lot of contradictory information. Is there a general consensus these days on how to approach phase and time alignment when it comes to crossover design?

Or am I completely misunderstanding things? Was my initial presupposition false, and indeed perfect time alignment across the entire frequency range of a passively filtered multi way speaker realistically achievable?

Tentatively, my thinking has been to focus on average group delay, then try for high order slopes with the lowest order electrical filters possible at crossover points at frequencies we're not as sensitive to (sub 500, which i am guessing is also helped by longer wavelengths? and above 5k?)

Thank you in advance. It is a testament to the kind heart of this community that I am progressing at all! (Not the sharpest tool in the tool thing 😋)

Hi all, anyone heard from @Gnobuddy recently? Miss his contributions, hope he is ok

I could swear I read somewhere that there is a direct replacement IC for the venerable 555 timer that has 10 times better temperature stability. Was I dreaming, or is there such a device?

Received a cheap PA amp for repair. Analog with mosfets irfp240.
Can't find this part. maybe triac d8d 66 3 legs, and what type of fuse is this?

I just had to clean out Grandpas shop, he repaired Ham Radios and amplifiers among many other things and although I recycled many items, there is a ton of components left that I thought I could try to sell before recycling it. There is a lot of items available and I am listing them here. I cannot possibly inventory and list every part here, you can look at the pictures of the hoard and see if you are interested. I won't sell individual items since It would require that I sit on the pile for too long so I will try to sell it all in one batch, maybe two. NO INTERNATIONAL SHIPPING, US ONLY. The shipping to outside the US would be cost prohibitive.

If you have questions or comments, feel free to PM me, I'll return your inquiry ASAP.

I did find a couple Simpson 260's (one for parts and one works great), thousands of OP-Amps, transistors/resistors/diodes/and a buttload of caps. I tossed the PIO and Electrolytics due to age. I also tossed most of the used components but there still may be some dispersed thorough the haul. Shipping will not be cheap but many of the items are obsolete parts and would be great to have as repair parts if you have the room. I don't happen to have the room or I would keep them. Gramps came from the days when it was a sin to throw stuff out so his 50 year collection was large. I have tubes and a tester I will be selling and I don't have the time to start testing the hundreds of tubes in the hoard. I will handle the tube stuff later unless somebody take the whole thing tubes/tester for a nice price. I do NOT know the condition of the tubes. Some will be NOS, some won't. The price will reflect that. I'm not even sure if the tester works but it's a Hickock KS-5727-L1

I am attaching picture right now so stay tuned. I started with a hand written list but there is TOO MUCH!!! Delivery is possible if you are close to Minneapolis. If no interest here, I'll take it down and list it on the BAY

Thanks

Perry

Struggling with this amp. Owner accidently connected speaker to ground when amp was on.
Repaired ps, and audio parts. Output transistors tip 35c and 36c are ok.
Changed 2q209 and 2q10. Other channel works fine. Tested most parts, can't find any damage. Audio ist disorted in higher frequency. Signal are at the base of the tip transistors without transistors inside. Voltage at base is also a lot different..
Bias transistor was also damaged.

Hey group,
I have an open baffle build that I'm really happy with- its an active 3-way with GRS 18PT in a H-frame woofer, Dayton DMA105-8, and some legacy Monsoon planar tweeters. Xovers are at 200hz, and 2500hz. I have a sealed 10" sub doing the very last bit of bass, crossed over at 50hz.

The 18" woofers can play down to 30hz without trouble. Not using a high pass with them, just letting them roll off to the sub.

System sounds incredible and i'd suggest it to anyone who has the space.

Unfortunately, my spouse has recently been dropping hints that the 24x24" H-frame woofer cabinets may be "too big for the space".

Soo- I can't replace the spouse but I can replace the woofers. I'd be looking for a smaller (<=10") woofer to cover the 80-300hz range. Then i'd adjust the cross overs to the sealed sub for around 80-100hz.

Anyone have any favorites for this application? I usually buy from PE, my budget isn't quite up for Madisound drivers.

1. Due to degraded sound in my Marantz PM5004 , I checked the bias VRs and found that the bias were 2.1V and 3.2V LR channels. I have readjusted the bias according to the chinese manual i.e 5mV but still with the recommended setting I was not satisfied cause the sound was still dull and lacked lower end. I have slightly increased to 7 mV and immediately there was a noticeable improvement. I would like to know how much more increase is possible to get the best sound and at the same time avoid damage to the power transistors 2SA1649 2SC4467. With 7mV the heat sink is just slightly warm.
2. I would like to upgrade the power capacitors Koshin 6800uF x2. What would you recommend?
3. Is it possible to increase just slightly the input signal in the preamp so as to get a little more output from the speakers without any distortion? If so how to proceed? I am just a hobbyist and have no special equipment .. no oscilloscope etc to check the signal waveform.
4. Lastly what other upgrades can be done to improve the sound?

Am the new owner of a pair of Jamo MFB 300 active speakers.
Being made in 1978, the speakers need to be updated with new electrolytic capacitors and relays. Then they should be calibrated with correct bias for and output level to the 3 output amplifiers. And the feedback loop for the speakers sensor should also be checked/calibrated.

There is an owners manual with diagram and component value. This one I have.
Measure-points and values for the data mentioned above are not in this manual.
Jamo was originally a danish company but has ceased. I think 14 years ago. The name is owned by Klipschgroup and they still produce loudspeakers, now made in China.
Do anyone here have any information of the data I am seeking or can possibly point me to where it can found?
I hope this information is still available somewhere.

Scope with:
2 channels.
No trigger, positive trigger and negative trigger.
200v input max with x100 scope probe.
20v input with x10 probe.
2v input with x1 probe.
AC/DC mode switches.
20 mega samples and 1MHz bandwidth.
Scope mode and spectrum analyser mode.
Comes with USB interface and Windows software on CDROM and brief instructions.
Ideal for audio work.
£35 to UK. £50 to rest of world.

Is the Scientific Method applicable to Audio?
Certainly yes, if you mean about Audio Technology.

Is the State of the Art of Audio Technology "satisfactory"?
I mean, is the State of the Art of audio technology satisfactory in bringing the choice of an audio device that has certain "qualities" to Listening?

In other words, is the Scientific Method also applicable to Listening?

Certainly not exactly, as Science is not able to measure the perceptions of Listening and cannot give indications relating to the timbre that must be expected from a device or the kind of the sound-image, or the clarity and sweetness of the medium, or the solidity of the bass or the silkiness of the high frequencies without listening to it first (by connecting it in a pre-configured and already known audio-system).

It seems that not being physical quantities there is no way to measure them.

Does this mean that Listening is more important than Science and Technology?

Your knowledge and your (even irrational) thoughts are more than welcome.

Thank you

Hallo,
I am new to this forum and quite new to the audiophile world.
I need your expert advice to reverse-engineer a project that I would like to build with my CNC.

I have seen a thread regarding the Boenicke W5 clone. Very cool but I want to work on an existing alternative design.
In this Italian forum I have found a project called Rona created by a well-known speaker designer (A. Bellino – btw check some of its projects if you have time) who unfortunately stopped the activity. I tried to get in touch but no luck. I know for a fact that those speakers were built and sold on request in 2016/17.

Here

The design concept is very similar to the w5.
As you can see, there are drawings, drivers, crossover schematic and the frequency response.
In principle, all I need.
Using the benefit of the CNC, my idea is to tilt 8degrees the front and the back (keeping the overall internal volume), round some internal corners and maybe even integrate the reflex changing the section from round to square (with the same section area).

I have created the 3D model with the purpose to run some simulations.
I am pretty good at modelling, but a complete looser beginner at designing speakers. So, as expected, I got lost pretty quickly.
Here are my problems:

Woofer –SPH-130AL
· After removing the volume of the reflex, the tweeter and the woofer itself, the true volume of free air left in the box is about 3.35liter. If I force Winisd to work with that volume (and with the given spec of the reflex) the resulting Fs is 68Hz. Is that an issue? Can the woofer work properly with that volume of air?

Full-range SPX-31M
· The full-range driver can barely fit in that space. I know It is a "Closed-box" design, but it looks very "Closed" to me (0.17liter of free air). Once again Winisd would prefer different numbers…. Can that work?

Overall
· The drivers are firing in 3 different directions. What about the phase? Do I need to care?
· Is the diffraction an issue for this design? Rounded corners or not?
· Is the crossover working? Meaning: does it make sense to you guys? I simulate the Crossover in Vituixcad but with the values in the post nothing works for me. The response is all over the place. What do I do wrong?
· The project is from 2016 so maybe in 2022 I could use better drivers. Even the ones used on the Boenicke W5. Any advice?

I have 0 experience and 0 professional equipment to simulate and measure……..
I need some help to get to the finish line. I just don’t want to blindly copy a project with the risk that it doesn’t work. I would like to understand.
I bet that there are many experts in this forum who could run correct simulations to validate the design (or not).
I am more than happy to take care of the modelling, share the 3D and create dfx/toolpath for the CNC once I have confidence that the design could work.

Is someone interested?
Can someone help?
In my opinion this W5 alternative could be a very cool and cheap DIY project. Cool enough to compete with the w5 clone.

Thanks a lot

Fliege 1kHz notch filter project PCB +Twin-T notch PCB

EDIT 1/25/2016 - This thread was just about the Fliege notch filter, but I've added a twin-T notch board in post #62.

*****

The Q401 THD analyzer coming out reminded me about an attempt I made early last year to make a Fliege 1kHz notch filter:

http://www.diyaudio.com/forums/equipment-tools/231401-quantasylum-qa400-17.html#post3821237 (post804)

The notch filter worked quite well, but it also self-oscillated at 100mHz. Oops. 😱 I've had the thing on the back burner since then, but just re-did the layout to reduce the opportunity for stray outout-to-input coupling and sent it out to fabrication a couple of days ago. If this one works when it comes back I'll post the Gerbers.

Info on the Fliege notch filter from TI:

www.ti.com/lit/an/slyt235/slyt235.pdf (opens PDF)

www.ti.com/lit/an/sloa096/sloa096.pdf (opens PDF)


Some of the features:

• The Fliege notch filter (which is unity gain) is followed here by an optionally-populated post-amp and current buffer. I have OPA627 (gain of up to 5) and OPA637 (gain of up to 50) penciled in the BOM for the loop op-amp. The post-amplifier can simply be left unpopulated. I have a resistor position (which can also just be a jumper) on the board which bypasses it entirely and runs the filter output directly to the output BNC.
• I have an optional (film) couplng cap and (if you use it) ground return resistor for the OPA6x7 op amp input if someone wishes to block any DC coming in from the source and filter. The OPA6x7 should result in less than 200uV of DC offset (less than 100uV with high grade). I'm using a OPA2140 + BUF634 in another project on the forum and I've measured that at a real-world 47uV.
• Can use either the on-board 9V battery clips (2 x 9V = 18Vdc per rail), OR onboard AC supply (16Vac 500mA transformer, WAU16-500), OR an external +/- lab supply. Just populate what you want.
• I've included a regulated power supply using the LT3015 and LT3080. I've used those in another project here on the forum and they work quite well. I'm using the LT3080 instead of the LT1963A because it has a matching 30V maximum input to the LT3015. The 1963A is only 20V. Both vregs are noise bypassed per the data sheets.
• The vregs are adjustable. The BOM parts set them at +/-15.3Vdc since that is the max you can realistically get with a 16Vac transformer and expected line voltage fluctuations.
• I've set the batteries up for two 9V (PP3) on each rail. Depending on how fresh your batteries are that should work out to be 16Vdc - 18Vdc or so. It was tempting to leave off the voltage regulators entirely (be my guest, they are easy enough to simply not populate and jumper accross) since the chips all have absolute maximums of +/-18Vdc, but that little voice of past experience keeps telling me stay at least 1v away from absolute max. I used two batteries per rail under the assumption that higher chip voltages may result is slightly lower THD, rather than just going with the lower 9V per rail (QuantAsylum, I'm looking at you here).
• One of the two "critical" parts are the 0.047uF capacitor. In tight tolerance those are a bit pricey and hard(er) to find in stock. The 1206 COG MLCC 1% I used in last years version is already unobtanium. So I've put three pads in parallel for more options. One is a 1206 for last years's part which I still have a few, a 0805 for a current 1% COG Mouser has in stock, and through-hole pads for a 2% film polypropylene Mouser has right now. The TI white paper on the Fliege in the link notes that in the lab the COG/NPO worked fine but the X7R essentially destroyed the notch quality. Dielectric matters here.
• And the other "critical" part is the 88.7K resistor, another harder to find value. Once again I've hedged by bet with two series resistors. More combinations to add up to the right value, plus adding another 27R in the second position further fine tunes the notch. I've put a 2.5 x 7.2mm through-hole resistor pad in parallel with the 88.7K because Mouser just happens to have two 0.1% 88.7K, for fairly cheap ($1.50 or so) and one is even lower tempco than the SMD thin film (15PPM vs. 25PPM/C).
• I've used the soon-to-be-extinct but excellent LME49990's for the two filter chips.
• The schematic has the part number of most everything next to it.

Ian Canada TransportPi with low noise LT3045 regulator.

55,- euro excl. shipping or trade against RecieverPi.

I'm starting a new thread here in the Analogue Source forum as I don't seem to be getting any responses in the original thread which can be found here:

http://www.diyaudio.com/forums/tubes-valves/202761-sonic-frontiers-sfp-1-phono-stage.html

I have had an SFP-1 in my main system for nearly 15 years now and it has been rock solid, until a couple of weeks ago. I have always used the MC input and have never switched it to MM. Recently I have been hearing a random popping and crackling in the left channel only. My first thought was a bad tube as the ones in the unit have been there for over a decade. I tried re-seating all of the tubes, no change in the noise. I then swapped the left and right channel tubes, but the noise still remained in the left channel. Strange. I then cleaned the MC/MM internal switches on both channels, cleaned the tube sockets and pins, but there is still noise in the left channel. Now I'm thinking it's not likely a tube issue. To confirm this I switch both channels to MM mode and there is no noise. OK, on to the MC FET stage for the left channel. I first replaced the B+ supply resistor that drops to the B+ to ~10V, no change. I then swapped out the J310 FET with a new replacement, still no change. Now I'm confused as to what the issue could be. I touched up all of the solder joints in that section and it did not help. Now I'm down to replacing all of the resistors in that stage, but before I do I'd like some guidance as to what might be the cause. Is it in any way possible it could still be a tube issue, even though they are quiet in MM mode? The MC signal goes through the same stages, so I'm not sure how that could be.

Thanks!

P.S. Schematics can be found in the linked thread.

Hi,

I built 2 prototypes of push-pull KT88 amplifiers, with 3.9K 33% ultra linear / 12% cathode feedback transformer (3.9K with cathode feedback connected).
Power transformer is multiple tap so B+ can be anywhere from 400 to 500V.
Now, before assembling final variant, would like to get rid of fixed bias circuit and switch to cathode bias, with 490 - 500V B+ and 520 Ohm cathode resistor (2 x 5W metal film resistors, 300 + 220 = 520 Ohm total). Drop of max output power is not a problem.

Few questions regarding new setup.

1) According to Genalex data sheet (attached), cathode bias configuration requires transformer with higher primary impedance (around 6K / 500V B+), instead of fixed bias 4.5K / 560V B+. Is that really correct?
2) What is recommended value of cathode bias resistor bypass capacitor? I saw a value of 50uF 100V. Going to use several 10uF / 22uF metal film capacitors, they are very cheap today.
3) I'm going to connect cathode feedback winding right between valve cathode and cathode bias resistor. I assume it should just work, or am I miss something?
4) In same data sheet IMD (intermodulation distortion) 50W cathode bias = 4%, yet IMD 70W fixed bias = 10%. Although output power is different (50W vs 70W), does cathode bias really have advantage of lower IMD at same output power?

Thanks in advance for any suggestion(s).
Andrei

want to buy quality 300B transformers ( TANGO , HASHIMOTO , Monolith magnetics , etc.. ) between 3K to 5K primary and minimum 60ma
From EU will be the best to avoid expensive shipping and Custom costs.

Let me know

thanks

On a couple of occasions I have complained a bit about the bass on the Fane 12-250TC.
I recently built up the first amp for a good while that had tone controls.
With the bass turned up the Fane has some serious bass.
I was surprised how much.
I take back what I said previously.
Looking at the spec's it has 5Hz more bass than the Fane 15-300TC
I have a pair of 12-250TC's in a sealed box which sounds great.

I have two Wright WPA3.5 monoblock amplifiers modified to work with 45 tubes at 180 plate amp voltage. When modifying them a wierd thing was happening. The same configuration of the same value power reducing resistors resulted in two different results on the two amplifiers. One the expected same value and one half the value. Back then I solved this problem adding another same size 4K7 resistor in series to end up with the same measurement and VDC on both amplifiers and they have worked well. Now I want to figure out why it is happening and fix the underlying cause. All four Audio Note tantalum 4K7 resistors test 4K7 when unattached. Both 80 tubes have been tested and swapped out with others. Both 80 tubes are turned the correct direction. I was careful to install both sides in the exact same configuration but I still get half the measure. I even switched the yellow heater wires and nothing changed. Does anyone have any suggestions why this is happening? I have included pictures. In the left side picture the red wire was attached when testing. Thank you for the help.

I bought two of them and after short period of time both developed problems with drawer mech which I'm not able to fix . Drawers need a little push to close and open . I lubricated the right spots, replaced belts to no avail. It's a cheap plastic junk which unfortunately was used in fairly expensive players.
I would be willing to buy transport mechanism with bad laser but properly functioning drawer since I have two good laser heads mechs I already bought.

A while back I built a Pass F5T and it was delightful - except for a small hum I was getting from my speakers. I've gotten a hum before on a different amp (Akitika GT-102, LM386 chip amp) but recall that hum was a physical one from the transformer. This hum, from the F5T was decidedly from the speaker, not the physical amp.

What are the chances the hum was coming in through the wall AC? Now that the amp is gone, and I never did bring my speakers and amp to someone else's house to see if I had the same issue; is there a way to see if my house AC has got a hum? Like an oscilloscope? or something?

Now that I'm thinking back on it, I wish I would have shut off every breaker in my house, then only turned on the one with the power for the amp: see if that does anything. I'd like to get another sweet amp situation going, but I really don't want to run into this infamous hum again.

Any ideas?

ACA March 2018 Build guide can be found here: ACA (v1.1) Illustrated Build Guide

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An illustrated guide to building the Nelson Pass 'Amp Camp Amp'.

First read Nelson Pass’ article on Amp Camp Amp #1 if you haven’t already:
Amp Camp Amp #1

Another great guide can be found here - http://www.diyaudio.com/forums/diyaudio-store/221212-amp-camp-amp-1-pictorial-build-guide.html


Click into any photo for full-size.


The Chassis shipping box. Not very large, but quite interesting…


Careful packing is always a good sign.


They just seem to be the perfect size.


The chassis pieces exploded.


Chassis hardware.


The heatsinks are pre-drilled and tapped. Everything just screws together.


Parts kit contents - Left to right, wire, chassis connections, resistors and capacitors, transistors (in protective mylar bag), circuit boards and insulators.


Circuit boards and the Keratherm insulators for the power transistors.


Enough wire to make all the connections necessary.


Resistors, capacitors, potentiometers.


Power switches, chassis connections (power, RCA input, speaker output), hardware.


ZTX transistors, MOSFET power transistors (the big ones), LEDs


LSK170 transistor. Don't confuse it with the ZTX transistor.


Time to get some tools. Digital Multi-Meter (DMM), screwdrivers, pliers, diagonal cutters or "dikes"(flush-cut is best), wire stripper, zip-ties. Also a soldering iron and solder of course. Those with kit V1.3 have a choice of two different power jacks, which will be discussed further on. For one of these choices the hole in each chassis for the DC power Jack needs to be enlarged about a millimeter which will require a round file, Dremel tool, taper reamer or similar. The other choice doesn't require any enlargement of the chassis hole, but is slightly harder to wire.


Time to stuff the PCB.

AT THE MINIMUM you need to have the schematic and parts list in front of you, and your DMM out, ready to measure the resistors.

Measure the value of every resistor with your meter before stuffing/soldering into the PCB. This will save headaches later.


I strongly suggest aligning the resistors in one direction, with the value showing out. This will assist in troubleshooting later if there is any problem. Start inserting the small items first.


The small resistors have the value marked on them - here you can see the value of 100 Ohm and other markings


Again, the various markings and the value of 1K ohm. A common mistake is to overlook the "K" if it's in the value. Since "K" means "x1000" this is very important!


The large 3 Watt resistors also have the value printed on them - here 0.68ohm


Bend the component leads out a little before soldering to hold them in place.


Placement of the large resistors.


Capacitors that are used in this amp are "polar". In other words they have plus and minus leads. This polarity is shown in 2 ways - the negative lead is shorter and the label on the can next to this lead has minus signs. (---). The positive lead is longer. The positive hole in the PCB is marked with a +






Parts placement. Don't install or solder the Power Mosfets Q1 and Q2 yet



Please note On this photo you can see that the pads or icons printed on the PCB indicating the location of the small transistors (Q3 and Q4) have a shape to them - there is a flat side and a rounded side - The transistors also have a flat side and a rounded side and must be inserted to correspond with the printed pad, as it's essential that they not be installed backwards. In this particular amp the flat side of both the small transistors should face the biggest capacitor.


Now it’s time to bend the leads of the power Mosfets. If you bend the legs up close to the point where the pins narrow, it should fit perfectly.


Use the screw and washer to mount the Mosfets to the heatsink with the Keratherm insulators between them. Keratherm insulators have exceptional heat transfer characteristics but must not be used with thermal grease. The insulators often have a backing, larger than the insulator. If so, just peel the insulator which is the rubbery beige rectangle off of the mylar or fabric-like backing. DO NOT cut out the backing with the insulator as that would decrease heat transfer tremendously!


Also mount the brass standoffs as shown. Don't over-tighten them. An eighth of a turn after they barely contact the heatsink is plenty


The PCB mounts to the standoffs with the screw and a washer on each side of the PCB.
Slide the PCB down over the leads of Mosfets Q1 and Q2




Now solder the Mosfet leads to the PCB.


If you decided to solder the wires inserted from the top, which is a fine way to do it, make sure to check that the ends of the wires do not touch the heatsink or anything else under the PCB.

Put the heatsink/PCB assembly aside for a moment and turn to the rest of the chassis.


This is all the parts to the RCA jack. Notice that one of the washers has a shoulder - this needs to go inside the chassis hole to keep the metal of the jack from touching the chassis.




Also note that the ground tab goes outside the washer but under the nut.


The speaker terminals - to isolate them from the chassis the plastic washers go on either side of the chassis wall. The 2 nuts go inside, tightened one on top of the other, to lock them in place.



The connections installed, as seen from the interior.


The power connector. Note it has 3 prongs, but we'll only use 2.


This is the proper wiring for the power jack. The red wire is positive, connected to the pin that touches the center. The black wire is negative and attached to the “middle” tab. The leftmost tab (in this photo) is unused. Make sure the wires don’t touch anything other than their tabs.

In some V1.3 kits there are two power jack choices. One set is exactly as discussed above except that the large washers packed with it must go on either side of the chassis wall to make it fit firmly. The second jack option has only two terminals, with the center being positive, which cuts down on confusion, however it is slightly bigger in diameter than the holes in the chassis. For this reason if you decide to use this power jack you must slightly enlarge whichever of the larger 2 holes you decide to use for the jack using a round file, Dremel tool, tapered reamer, or large drill bit.

Before installing the power jack in the chassis leave the PSU unplugged from the AC electrical wall receptacle and insert the plug from the PSU into the power jack. Then plug the PSU into the wall receptacle and use your voltmeter to identify the +19v connection tab and negative tab as discussed above. Now you can install the power jack into chassis.

This amp is in some kind of shutdown mode.The power led is on and the ESP led is blinking.I see no rail voltage.

SG3525
1: 0.00
2: 5.15
3: 0.12
4: 0.382
5: 2.072
6: 3.766
7: 2.017
8: 0.262
9: 6.42
10: 1.586
11: 0.035
12: 0.001
13: 13.23
14: 0.007
15: 13.24
16: 5.17

393
1: 0.086
2: 3.994
3: 2.729
4: 0.000
5: 0.058
6: 5.17
7:0.125
8: 13.21

Any suggestion?

The best music tube amplifier, this machine adopts 4*EL84.3*ecc83.1*GZ34 designed by music tube, the whole machine transformer adopts PATRIDGE double C design, and the output transformer is P4131. This is the best material in the world. The circuit is carefully designed, the parameters are up to standard after computer simulation, and the materials in the 1950s and 1960s are carefully selected. The test parameters meet the design requirements (with waveform diagram) and the sound reaches the best balance.

Does anybody know whitch CD drive mechanism is the best. Is there any meassurements anywere on whitch drive reads most corectly the data on the CD?

What characterize a high class drive?

Hi,

My Sansui AU9900A when powered on does not get past the relay eg no relay click and the LED does not change colour, was working fine before this.

Has anyone who owns this model encountered such?

Thanks!

I am not a headphone guy, but this topic is interesting.

Use the U1 chip in your iPhone to scan your ear lobes and the H2 computer will tweak things for your head and ears.

https://www.apple.com/ca/airpods-pro/

dave

Im wondering if anyone here has a suitable case for an icepower module thats pre drilled for rca and speaker binding posts or better yet is already made and installed. Being disabled and living on disability Im always looking for the best bang for my buck. I know ghent audio has a pre made ready to go kit but its like 145 which is more than I paid for the board lol.

Please Pm if so.

Thanks!

What Glee I felt when my local Charity Shop offered a pair of Wharfedale Super Linton loudspeakers for a mere £30! Supposed Classics from the early 1970's!

As an expert in cheap two way loudspeakers, I thought I would breeze through this. How WRONG I was, how HORRIBLY, HORRIBLY WRONG!

First off, the 5.8R tweeters were wrecked:



Interestingly, the Wharfedale Purple Jellyfish tweeter bears a passing resemblance to the Henry Kloss Fried Egg tweeter.

But since they were fried, I lost interest.

Decided to replace them with Visaton DT94-8 91dB mylar tweeters:



After some thought, I added a foam ring surround:



All went swimmingly well with Miss Diana Krall playing Jazz. Alas Leonard Cohen wrecked my Party with his bassy efforts. Sounded horrible! All distorted. Voice-coil rubbing I think.

I concluded that not only were the tweeters fried, but the 4.1R basses were wrecked too!

For the interested student here is the simplistic filter:



I swapped the 8uF for a more sensible 4.7uF.



Considering I paid an outrageous £30 for this ancient 50-y-o Wharfedale garbage, I am fairly unhappy at the outcome.

Only salvage I can think of is to fit some new Faital-Pro drivers:

https://www.bluearan.co.uk/index.php?id=FTP8FE200AF

Problem being the cutout on the bass is 178mm and maximum diameter allowed is 222mm. I can doubtless find another 91dB tweeter somewhere.

Couldn't find this after moving, ordered another to build my amp. Then found it. Hoping someone can use it.
Asking $75 shipped (ground to lower 48).
PM me if interested.
Still sealed in original box.

Thanks,

Brad in NM

NOTE: This is the black chassis


SOLD.

Having lived and refining my DIY dipoles I'm very happy how they render recording. Obviously the Orions are my dream speakers which I would never afford with such mortgage . The dipoles are very untiring and natural to hear albeit their obvious limitations in Bass and transition to dome tweeters (are addressed in JohnK's Nao Note).

Then I read Orion owners hearing the constant directivity loudspeakers (gedlee) and buying them in droves (exaggeration ..). Ok ... so perhaps great dynamics are good. OK so I will investigate myself that by building a CD loudpeakers (Econo-waveguide), 98db and all this weekend. I'll report what's all the fuss is about in different thread.

Now, in 2009 SL announced challange to audio community to investigate optimum polar response for realistic reproduction. So this is old news.

linkwitzlab.com/publications.htm
"The challenge to find the optimum radiation pattern and placement of stereo loudspeakers in a room for the creation of phantom sources and simultaneous masking of real sources"

What I did not know was that a group of well-recognised audiophiles had taken the challenge:

home.provide.net/~djcarlst/smwtms.htm



This was quite seriously organised. ABX, Blind, FR matched etc. A large number of samples too. Dave Clark is an audio engineer and he is well known so I think this response to the challenge is credible. They use 3 speakers for the challenge:
- Linkwitz Orion
- Behringer B2031A
- A strange diy loudspekers, the "IMP" by Gary Eickmeier

Have a read yourself to the result:

home.provide.net/~djcarlst/SLReport10.05.pdf

mirror: http://www.scribd.com/doc/103681479/SLReport10-05

- The Orion was beaten by the dinky Behringer slightly
- The Behringer was beaten by the "IMP"

They were so surprised as well:

1.How did Eickmeier’s cheesy boxes of multiple cheap in-walls come out on top?
2.Why didn’t the Orions in optimum location blow away the references and everything else?
3.Why didn’t placing the Orions near walls hurt their sound more?
4.Why were all the averages clustered around 0.0 (equal to the reference)?


What are the implications for all these for our hobby especially dipole lovers?? I'm surely very excited to complete my CD horns and hear myself. But to build an IMP???

I haven't read any response from SL in regards to this investigation but it surely was interesting enough that he did the investigation himself:
linkwitzlab.com/frontiers_6.htm#Z%20-

He thinks now that the CD box loudspeaker can be a more accurate reproduction tool?

To put things in perspective, the Orions are $9000 loudspeakers and the Behringers are $360.

I have an old Omnisub 8 mini.
It blew a fuse, tried replacing it and it blows gain immediately.
I can see nothing obviously burnt and the caps seem OK.

Could it be one or both of the IRF 730 Mosfets on the power supply?
I tried testing them in circuit and they both show a short between the D and S pins.
G and S shows short on one of them but not on the other. You can see the two of them towards the top of the picture attached to the heat-sink

I suppose the only proper way to check them would to first desolder them from the PCB but just looking for a little direction before hauling out the soldering iron.

Thanks

atriad by streak3, on Flickr

Hi,

sorry for my English, just picked up a Denon DCD-3560 CD Player, i disassembled the mechanics and the "rubbers" are crumbled. Reference 15 in the service manual is
462 0083 005 H. DAMPER has anyone managed to rebuild them or do they have the drawings or idea for repair?

To get more mounting options I decided to put output power MOSFETs on their own tiny boards together with their source and gate resistors. So they have their own power rails. Is it necessary to decouple them too (and route return paths to the star grounding point)? The driver board has its own decoupling obviously.

Side note: those MOSFETs are gain (pure transconductance, not followers) devices actually similar to Hiraga's amp, Pass's amps and many others.

I've a head end unit from a console stereo that is in the shop for repair (one channel not working).

I've looked all over for a schematic for this unit and came up dry.

Can anyone point me to a source for this documentation?

Below is customer photo of faceplate and below that are chassis photos I took.

I acquired a Urie/JBL 6230 a few months ago. It’s in my Garage system and is performing well but it seems to be running Pretty Warm. I’d like to get the bias setting checked to make sure it’s correct. .350v seems to be the correct setting from my research. Anybody in the CA Bay Area that could provide this service?
Thank You
Randy

I‘ve never heard of this ‘half stereo’ designation before (see pic) also including link to the whole manual.

https://www.parasound.com/pdfs/vintage/hca600om.pdf

Hello all,

I need some help deciding what to do with the output stage of my pre-amp. Seems their are a lot of people in this forum who know about properly utilizing opamps, and that's really what this is about.

Below is the schematic, with some notes. This is a pre-built circuit that was supposed to have dual AD797 opamps, but the manufacturer pulled a fast one and installed dual L49710 opamps instead. Furthermore, caps C402 and C405 were not WIMA, but some generic junk. I have replaced those with WIMA FKP3 and the sound quality improved dramatically. However, I suspect that this circuit is still not what it could be.

Can anyone offer any guidance on a couple of points? I have spent some time with the datasheets of the various parts, but cannot wrap my brain around it all.

1) Since the schematic specifies AD797, is it safe to assume the circuit is designed well to work with that opamp? I do know that the AD797 requires special care to implement (esp. power supply bipassing) correctly.

2) Does a simple replacement of L49710 even make sense here? Sure, it is a good opamp, but different opamps require different circuits, no? (perhaps leads to the next question)

3) Why have they omitted C404 and C408? Could it be that they are not required, due to the different opamp being installed?

4) Even if you can't or don't want to answer the above questions, do you have any advice on what you would do to improve the circuit?

The simplest thing for me to do would be to replace the L49710 opamps with AD797 opamps and install 22pF caps at C404 and C408 (as per schematic), but I will only do this if I can have someone confirm that it is a good circuit.

Thanks in advance for any advice and opinions offered.

And so the next chapter of conversion starts, proberbly the hardest one as i want to do it on the existing board if i can

On the left an early 'A' version that was still in series 20 colours-later they became the traditional dull grey format
On the right a late series 20

not too different are they

Ive been trying to fix mufollower with 6sn7 always some sort of hum and little hf noise.
Fedup with it thinking to move to cathode follower for preamp application. Is it right to move to cathode follower?

this is the DRV134 circuit/diagram



The audio transformer was (in this case the pic was using Lundahl 1545a) was wired to the XLR input and then to the amp.


I've looked at the Lundalh 1545a datasheet but I can't understand how to wire it.

Thank you.

Hi there,
I want to build a boombox-style all integrated internet radio. I already have all the parts: screen, SBC, amp, DAC, 2 full range drivers and 2 passive radiators. So basically all the electronic parts and the screen will sit in the middle of the box and the speakers on each side with the passive radiators on their back. My question is: is it better to have each speaker with its passive radiator in a sealed compartment, basically acting as two separate speakers, or have an all open box, as you often see in bluetooth speaker builds. I am basically wondering if it's better to have more volume for the speakers through an open box, but then I wonder if the two radiators would not interfere which each other when the air inside the box is moved by both drivers? Thanks 🙂

I've been reading a lot about THD, but it all seems to be about whqt it is not how it can affect music reproduction. Can anyone explain it in those terms?

I’m interested in experimenting with some of the different versions of VFET amps offered in the OS2 thread.

I have A few leads from other FS threads of people that bought genuine NOS devices before they disappeared from places like Acroman.

They don’t have to be matched, there are actually matched ones available in another thread…a bit too steep for me.

Same rating would be nice.

Any of the variations listed in title in pairs.

Shoot me a PM if you have anything.

Thanks

I am familiar with pro audio and hi-fi loudspeakers and am curious how cinema loudspeakers differ from the other two. I searched the forum looking for a thread that talked specifically about cinema loudspeaker design but didn’t have any luck. Any on-topic information is appreciated!

Hi, Im looking for a cheaper alternative than the ghent Audio pre made case kit for the ice power modules. Looking to build one with the 50asxse board and I find it crazy the enclosure is as much as the board. What are some good alternatives, preferably with precut back for speaker posts etc. Also I have a case from a class D amp Im not using, its for the TPA3255 and reason why that wouldnt work?

There was a recommendation to add more capacitance at the output of capacitance multiplier, and subsequent unanswered question as why is this recommended:
https://www.diyaudio.com/community/threads/sissysit-r-3.371272/post-7112259

I decided to check actual circuit behavior and give reasonably correct explanation.

Every power supply has voltage change at its output under load and, for an audio signal, amplifier is dynamic load that pulls current from the PS, at the output signal frequency and load current. How much will PS voltage vary, depends on its internal impedance at the required frequency. This impedance is kept low, with help of the final output capacitor. Any voltage drop at the output capacitor is “filled up” from the first reservoir capacitor (and transformer + rectifier) through resistance between them. In case of simple CRC, there is usually 0.11 Ω.
Capacitance multiplier follows cleaned voltage after RC filter with smoothed ripple and noise, supplied to the base of regulating transistor (Darlington in this case). Output is at the emitter and it simply follows voltage present at the base. Every transistor needs, with increasing current, more voltage between base and emitter. So, if load increases, as base is at the steady voltage, emitter voltage must drop to get required Vbe increase for the larger output current. That’s why capacitance multiplier output voltage under load varies substantially, the same or even more than with the CRC supply and should have a large capacitor at the output.

Nobody at diyAudio measures a damn thing when power supplies are in question. So, I made some PSRR and transient response measurements for the mentioned capacitance multiplier – Mark Johnson & Gtose design:
https://www.diyaudio.com/community/...sy-capacitance-multiplier.297921/post-6031533

First point worth to mention: PSRR changes a lot with load current! Measured at 120 Hz with 5 mF capacitor:
Another point: large output capacitor (68 mF) increases PSRR at all load currents by 6 – 8 dB.

Measurement from 20 Hz to 95 kHz at 1.7 A load, for the Cap Mx assembled using breadboard, so actual circuit could be several dB better, but not much.



Note: PSRR is not a level below some reference, rather PSRR is ratio between two values and shouldn’t be expressed as a negative number. Yes, usual representation in various datasheets with PSRR as some -XX dB number is wrong!

Transient response was checked with 1.7 A square wave load at 250 Hz and 1000 Hz, with 470 uF as base and then with 5 mF and 68 mF output capacitors. We can see that, with the small output capacitor, output voltage drops immediately, while with larger output capacitor voltage drop is smaller and gradual. At higher frequency, where internal capacitor ESR is lower and load time is shorter, drop is even smaller. Yellow trace is output voltage and blue is voltage drop across the 0.33 Ω resistor at the active load.







We can conclude that, as output capacitance or frequency is increased, voltage drop becomes smaller. It is 130 mV with small output capacitor and 40 mV with largest.
In case of power amplifier, 10 - 15 mF is not an optimal value at the output of capacitance multiplier circuit. We should use 33 – 47 mF, as with the standard CRC PS.

i dont understand 😝😝🤦🏼‍♂️

864/2.54

is 340.15748031496062992125984..(as 8/2.54 numbers)

clearly 15708,31416,62832,125664(as pi numbers)

3456/1/4 86.4

a one meter pendulum (86.4) swings an arc of 30 degres in one second at the equator )

0.8660254(cosine /sine 60/30 etc with
1.7320508

is there a connection here?

just like 0.52360 (30 degrees on a circle ) is the volume of a sphere when radius is 0.5 vs 1.0 (4.1887) 240 degres on a circle


1 vs 8

1/2.54 is 39.37(1 meter)(pi plus 0.0010)

8/2.54 is 314.96(pi plus 0.0080)


is everything really a circle has in its diameter or reference to?

I just can’t come up with the answer but these numbers and units of measure and how they fall onto a sideways or a circle etc. are mind-boggling at some point? I need to be slapped in the face with a trigonometry book to be fair and honest I haven’t looked into them so long this could be some of the dumbest questions and most obvious answers and I keep diving into an even number harmonics and how they’re canceled out in the cold filtering look perfectly aligned qw pipes where there’s a unique set of numbers just like this that exist as well?

Hope most of it fades quickly in reality due to Q losses , TS parameter inaccuracies and the whole concept of damping too much too little etc. etc.etc.

but you can get a definite set of workable numbers in simulation because you can get rid of all that and see what the answers would be in an ‘ideal situation… (if found and not requiring damping? )

Hi all,
A benefactor or someone with an ill intent has sprayed/splashed or applied some kind of smoking enhancer oil on an amplifier module (shown as my avatar). I sprayed the module several times and on separate occasions with a good quality contact cleaner. I would like to ask whether this is enough. In case the toroidal transformer is found to be contaminated with these hellish oils, what can I do?

Thanks for your replies.

Tested and functional !!! Headphone/preamp switch.Price 139€. Post 10€ Europe.Price only for material.

I have been looking at my mini DSP HD10x10 again recently noticed the A>D chips 5366 https://statics.cirrus.com/pubs/proDatasheet/CS5366_F5.pdf seems to use Tantalum 47uf caps around all the supplies. Very different to the D>A 4528 chip https://statics.cirrus.com/pubs/proDatasheet/CS42528_F3.pdf

I have added some local capacitance to the D>A 4528 and this did seem to improve performance. I wonder if swapping out or piggybacking the 47uf caps might be worthwhile (I understand they are usually Low ESR).

Hi all,

I'm playing around with various driver topologies, and I've come up with the following. It uses current mirrors to develop a voltage across a large value resistor RL.

The one thing I can't figure out is how to arrange this so that the output swings around 0V, rather than around ~150V as it does at the moment. I'd be very grateful for any suggestions.

Kind regards, Ed.

Hi All,
I've created a cross-platform mobile app called "Tonestack Kit" that builds on Dave Cigna and Duncan Munro's work in Duncan's Tonestack Calculator. The iOS version is available now in the App Store. I am in the process of testing the Android version and should have that available in the next few days.

Out of the box, the app includes the 7 of the 8 tonestacks in Duncan's TSC (plus Merlin's "Bone Ray" tonestack). There is an in-app purchase ($3.99) that adds an additional 12 tonestacks. Apple is a bit picky about the use of trademarked names, so there are some minor changes to the naming of the tonestacks. Here's the full list of available stacks, along with the full model and/or name in Duncan's TSC:

Free:
AB763 (Duncan's "Fender" circuit)
Plexi (Duncan's "Marshall" circuit)
DR103 (Duncan's "Hiwatt" circuit)
E-Series (Same as in TSC)
James (Same as in TSC)
Top Boost (Duncan's "Vox" circuit)
Tilt (Same as in TSC)
Bone Ray (Developed by Merlin Blencowe, "The Valve Wizard")

Full version adds:
60TC (Carlsbro 60TC)
6G7 (Fender Bandmaster)
Baxandall
Guitar Mate (Traynor Guitar Mate)
Voigt
18W Normal (Marshall 18W normal channel)
18W Tremolo (Marshall 18W tremolo channel)
5F2A (Fender Princeton)
6162 (Gretsch 6162 Twin Reverb)
Bridged-T (Bridged-T mid control, Gibson-style)
Bridged-T Alt (Bridged-T mid control, Framus-style)
Moonlight

The app has basically the same features as Duncan's TSC: you can fully edit the component values on a schematic-like layout, move sliders to simulate tone and/or volume knobs, load/save circuits, and export the chart and schematic as images or .csv files. Additionally, you can pan and zoom the chart and highlight guitar/bass frequencies on the chart.

After finishing the Android version, I'm going to take a short break, but eventually I would like to add a little more user control to the appearance of the chart (background color, line thickness, frequency range) as well as a darker "theme" to the app. I'd also like to investigate modelling some "active" tone controls, or ones with interactive channels.

Anyway, please try it out and feel free to ask any questions or for other features and/or tonestacks you'd like to see. I put a lot of work into developing a set of general algorithms I can use to model a given tonestack and handle the editable schematic, and it only takes me a couple of hours to add a new tonestack. If there's a particular one you'd like to see modeled, I'd be happy to add it to a future update.

I'd also like to thank Duncan for his assistance. I started this project a couple of years ago, and Duncan was kind enough to point me in the right direction back then when I was just getting started.

I’m changing bearings in my EPA 100 arms and it makes sense to rewire them at the same time. In the past I used Litz wire terminated with 5pin DIN plug for all tonearms that I ‘ve rewired.

I’m doubt I will get an audible improvement but I’d like to try running arm wires all the way from the cart to the phono stage inputs. I’m not sure what wire to use in this configuration. As EPA 100 arm has very low bearing friction Teflon insulation which is not flexible seems to be not a best choice for this arm. In addition dielectric constant of PTFE is 2 which is not a problem for less than 1ft wire but I’m planning to make 3ft cable so it is not insignificant. Finally as the wires outside the arm need shielding I'm thinking about using metal wire mech but I'm not sure what type of shield is use. Obviously absorption type of shielding material is preferred in the audio frequency range but shielding material with high permeability will attenuate the signal and I use LOMC so it is probably not desirable.

I am looking to build a portable speaker for auctions and need some help. I would like to build something similar to the Lectrosonic Voice projector. https://www.lectrosonics.com/phocadownload/vp18rman.pdfThis would be for auctions so voice only. It needs to be fairly compact and have sound enough for a crowd of 20-30 people. If possible I would like to power it off of a Milwaukee drill battery (18v). All this and be cost effective. Any help would be appreciated.

Making space in workshop.
I found 14 pcb Shiga MKII 2oz Cu, gold plated PCB.
I found several infrared remote boards as well and Quantum control boards.
More than 50pcs of LC78601 and over 50pcs of LA9242.
Custom made LCD displays, all transistors, are also available together with many other parts.

I,m looking for ~600 euro for all, or swap with one of the followings:
- mc cartridge
- turntable tonearm 9"
- mundorf mlytic or siemens sikorel capacitors >10.000uF/63V
- audiophile foil capacitors, duelund, mundorf, v-cap, rike, multicap, jupiter etc.
- anything else you may think an audiophile nerd may be interested 😉

Regards,
Tibi

Hello friends,
I am currently building a pair of DIY passive subwoofers for my home (mostly for TV and movies) with 200 watts RMS for each sub.
Since I am building a passive sub, I had bought miniDSP 2x4 HD version along with REW UMIK-1 mic for measurement. I will use them to measure the raw response of the subwoofers (after dialing in the gain) and correct/enhance the responses using house curve. Now, coming to selection of amp part is where I am stuck, class D or class AB. Given the RMS ratings for my subwoofers, I potentially look at these 2 right now - Crown xls 1002 (class D) or Crown xli 800 (class AB). With the below understanding of the pros and cons, could you please enable me to make an informed decision on my purchase? I really count the expert opinions here.

Option 1
Crown xls 1002 (350 watts, RMS?)
Pros:
1. Class D design, runs cool and draws little power, just about 18 watts at idle and 25 watts right below clipping
2. Sound quality (from what I've heard reviews about xls series is really good for subs)
3. Has additional DSP features (which I wont use as I have advanced DSP equipment, miniDSP)

Cons:
1. Due to its inbuild DSP capabilities, I believe it limits the output signal down to 48khz even though the input signal has a higher bandwidth (from miniDSP)?

Question - Do I really need to worry about the negative on limiting the output signal to 48khz?

Option 2
Crown xli 800 (300 watts, RMS?)
Pros:
1. Class AB sound quality is warm and better than class D
2. Since there is no inbuilt DSP on this amp, what is fed in comes out clean as output

Cons:
1. Highly inefficient as it draws 38 watts in idle and between 240 and above during normal operation and dissipates enormous amount of heat.

Option 3
Would I do better if I make an DIY class AB amp which puts out below 100 watts RMS? The idea behind this thinking is that with the miniDSP I have the capability to boost the input signal using EQ (on house curve by applying low shelf) and the amp would only need little power to make the subs play at desired levels of SPL (say 75 db)

With the above summary and given the fact that xli 800 which can consume lots of power, I feel crown xls 1002 would be better equipment for me. However, I am not certain on the signal bandwidth limitations I have highlighted in cons.

Please advise.

Thanks

Hi everyone,

I would like to ask for your tips and hints regarding the design of amp selector switch which is compatible with tube amps (but not limited to).
what I mean is a switch selecting between two or more amps into a single pair of speakers. Sharing my thoughts so far:

1. Assuming intended only for isolated amplifiers, is it necessary to switch both the positive and the negative outputs? i.e. is there a resaon why I should not tie all negative speakers output terminals of the two (or more) amps together permanently (still maintaing separation between left and right negatives terminals)? this is obviously a curcial question, as if both +/- outputs have to be switched, for every stereo amp I need to switch four poles.
2. For a generic tube amp, a common advice is that the amp output should not see an open load. Following this advice, I see two options- A) have a pilot load (100 Ohm resistor?) connected permanently to each amp output (input of the switching box). B) Use a shorting type selector (Make Before Break) with a neutral position between every two amps- an idea which was described here by Chris. I have to admit that I like the idea, but again supporting 2/3 amps, left+right, +/- switching, I have to find a selector switch with 8/12 poles and 3/5 positions. shorting type, which is quite hard to get (or very expansive).
3. Switch selector vs. relays- While shorting type selectors are not very common, with a uC controlled matrix of relays I can achieve any switching logic I want. I can have the uC switch the dummy load in before breaking the connection, I can have the dummy load permanently connected, or not connected at all. in the worst case, for every amp, two double pole ralys are required plus one additional dual pole relay for a full control over the dummy load. Quite std. relays, not hard to get. simple uC programing and custom PCB are not a big deal. The downsides- I have to design the PCB and the switching box requires power for the control gear.

I would appreciate sharing any constructive feedback.

Aviv.

A very nice little AK4490 DAC, with coax, optical and USB inputs. Well suited for office desktop or other space-conscious systems, but sounds good enough to use anywhere. Includes power supply, ready to go.

$80 delivered in the US.

Have anyone tried a wide band driver in a cardioid enclosure + waveguide/horn to control directivity in both the low and high end?

See the Directiva R2 plots from ASR forum:



In the above chart we can see cardioid behaviour from ~200 Hz to ~1000 Hz with the slots in the woofer enclosure.
Below 200 Hz we start to see cancellation which again governs the low end usability of the system.

Couldn't we then load the wide band driver in a waveguide to control directivity above 1000 Hz and get highly controlled directivity across the whole range?

I'm starting to design a subwoofer that is attempting to do what the Genelec W371A claims to do. I thought it was really interesting concept. It seems like a similar concept to using multiple subwoofers and DSP to get a flat bass response, except in this case the subwoofers are in the same cabinet.

Here is a preliminary drawing just to get things started. The cabinet volumes and port design are from VituixCAD. I'm a little surprised that the cabinet ended up being as small as this, but I'll take it!

Of course the design work isn't done. I want to make the cabinet a little wider so the 15" woofer fits better, I want to include a double thickness baffle, and I haven't accounted for the volume that will be taken up by the bracing that I haven't drawn yet. Or the volume the drivers themselves take up. So it'll be a little bigger than this, but atleast I know it will be a manageable size

The plan is for the 15" woofer to play from ~300hz down to ~60hz. (Genelec claims 500hz, but I don't if I need to go that high.) The 12" subwoofer is intended to play from ~200 to 20hz.

I already did some playing around with my subwoofers, and found that woofers oriented like this create peaks and nulls in different places in the 60-200hz range. Genelec says they use this effect to get a flatter bass response. That's what I'm hoping to achieve.

The 12" subwoofer will extend down to 20hz, and the left and right subwoofers will get some DSP treatment to try to flatten that range as well. This cabinet design is tuned to 17hz, but it only actually goes down to 20hz before dropping off the cliff.

Since this is a bit ambitious, I'm expecting to start with just 1 of these and do some testing. If it works out, I'll make it pretty and build a second one. I'll try to post here along the way, and I'd appreciate comments and suggestions.

Brought a pair of Rogers Studio 1 they were in fantastic shape cosmetically everything on the outside looked good as new...
When removed the backers to have a look inside found that one of the cross-over boards had been played with some of the resistors were missing and or bypassed. [One owner but he had passed away so no asking him]
They sounded Ok the one with the missing resistors sounded better to me...
The other had been played with but the parts were all there just not original.
So decided to replace the boards so both were the same as intended from the designer.
Sourced parts from Germany and Canada.
Audyn MKT radial / SCR audio capacitors and Mills and Kiwame resistors.
Some of the caps were different ratings board to board.
One had two caps at .68uf on one the other 1uf in the same place so changed them all to the same value of .68uf.
Things seem good the speakers both sound clean and clear so really happy with the way work.

Hello! I am interested in building a tube preamplifier for myself. I am not very experienced with the design side of these sorts of electronics, so I am thinking something like the Aikido kits/pcbs would be a good middle ground for me to start off with. I like the look of the octal preamps, but am open to whatever!

If anyone has an aikido, or honestly anything in the general realm of what I'm looking for, I would appreciate you letting me know! Thanks.

Hello, I recently got a cheap Chinese tube preamp, just to mess around. It says that it need 12v AC to work. Searching the web I ve seen many tube heaters working on DC, sometimes I read that you can use the two interchangeably. So I wanted to clear any misinformation.
What would happen if I where to power my 12 vAC pre Amp with DC ( 12 volt I guess shouldn't be enough). Will the answer depend on whether it's are using a bridge/tube rectifier or not?

Looking for VTL3A35 or a replacement. Any ideas? Analog servo controller and the opto-isolator died.

Thank you in advance.

Will there always be a perfect sine wave at the red dot if everything else is perfect? 🤔

This thread is a good example:
https://www.diyaudio.com/community/threads/available-again-audax-and-lpg-eton-drivers.195071
Nothing has been posted there in TEN YEARS! User HOPHANTHIET only made 33 posts in total, and their profile is dead. The person might be dead, too, given the events of the last years. But someone had the great idea to revive the thread by posting into it.

These old threads in the Marketplace should be closed to further posts by the mods after some period of inactivity, e.g. 1 year. Posts in non-marketplace forums might be given the same fate after no posts in, say, 5 years. Someone can always start a new thread and reference the old one via link, since they would still be available for reading.

Matched pair in good condition. Used with Purifi woofers until I went waveguides. I'm in NZ so shipping will need to be arranged. Can be spenny getting things out of here. Only 6 of the original screws - 2 missing, I don't suspect that would be a problem because they don't colour match anyway, I ended up using different fixings.

These are currently ~$1000USD a pair but this pair I'll let go for $600NZD/$530AUD/$385USD + shipping.

I have some original Sony SLD104AU Laser Diodes for sale. (About the half of a tray of 50)
Can I make someone happy?

Given the same voltage, same current rating: are shottkey diodes quieter compared to hexfreds? Why do many people use schottkey instead of high speed switching diodes?
Thanks in advance.

I turned on my trusty A85 and no sound. It switched on, the display works, the relays for the various inputs work (click and light up) but zero sound. I download the repair manual and opened it up. The two removable fuses are fine. The manual says to check the RL100A (volume control relay)....but no idea where this is (or how to test it.)

I realised that normally if I press 'Mute' on the remote there is a click from the machine. Now when I press 'Mute' there is no click sound although 'Mute' lights up on the screen so I think the mute relay is b*ggered...which I think is what the manual is suggesting.

Not sure it's worth a fortune to send off to a specialist - I'm reasonably practical (but not an electrical engineer!). Any ideas?

I attach the repair manual and photo of the internals.

I can see that the DIY DACs has come to life, but I don't see any progress around the output-analog stage. Always the same story with passive conversion or op.amps. In contrast, here is a slightly different solution, the input lamp receives the signal at the cathode and amplifies it and sends it further to the white cathode follower which gives an output with very low resistance .Russian 6S4P with cathode resistor correction can be used instead of 6HM5. Circuit has been tested for now with the current dac PCM1702 which outputs +/- 1.2mA (similar to AD1862) , it will soon be tested with +/- 3.2mA, in fact three PCM1702 in parallel. The power supply for the tubes was performed with a serial low-noise regulator for 260V, the circuit was modified with better reference and taken from ARC LS25MKII. All other important regulators in the DAC itself are shunt type from Mr. Walt Jung with low-noise op.amps and low-noise references. Special attention in the DAC is paid to power supplies and regulators which is really heard in the final sound.
I am now working on a new DAC with a TDA1547 that will also have tubes in the output stage section.

Can someone please identify this resister for me, is this orange/yellow/orange a 34K 2W resister? ALSO the manufacture used 2W resister throughout, can you please point out which resisters I can sub for 1W safety? I tend to leave the amp power on for a whole day at a time. I am trying to upgrade the amp but some the resisters I would like to use only comes 1W. The designer seems used all metal resisters, they all magnetic when touched by a magnate. Thank you so much!!

Griffin

RIP Joey DeFrancesco, August 25, 2022. 51 is too damn soon...

I found a paper copy of this (attached) schematic in my basement and it's simple enough to be interesting.

I am wondering if anyone recognizes it (Hiraga?). Reading about it will help keep me from misinterpreting too much.

I figured out some voltage drops and currents. I assume it's a small OTL power amp rather than a line stage. I wonder if the NFB (22k//3pF) also helps keep the DC nulled on the output, or is just classic AC NFB.

I had 4 pages stapled together, apparently from different sources so I can't assume too much. English 6C33C-B data sheet from user Cigna at Ohio.edu (1998), audiomatica.it curves for 6C33C-B, a Glass Audio spice model for same, and the Japanese schematic.

This topology doesn't provide me obvious 6C33C-B bias recognition, but if I imagine a load line based on V&I that produce typical 45W max.anode dissipation, I can see some sense. Still looks like a power amp after those thoughts, but is the bias stable? Hmmm...

If I knew/read more I might decide whether to keep the hard copy or bookmark it online.

Understanding it better might also help me recognize if the small NPN power transistors are the critical part of bias stability and the JFET's & current source PNP's are just preamp or interactive with the output bias too.

The 5687WA looks kind of like a DCCF, so there might be plenty of bias interaction.

OTL with multiple tubes always turns me off, but this appears relatively simple in comparison.

But if it's an unstable PA that produces about as much power as a line stage...maybe I'll spend my lunch money elsewhere. (The non-free part).

I have the tubes & power supply stuff, so it's briefly got my attention

Thanks

Murray

Nos caps, I buy this few years ago by hifi collective UK, but used maybe about 50 hours for cathode baypass in my ecc88 tube pre. This are 100uf/10 volts. This are great becose are verry small but with good sound. You can use this where the place is a problem, becose this are 10x8 mm big. Price would be 20 euro including shipping inside EU.

Greetings,

There is an open-source FetHead-like design: https://oshwlab.com/zipdox/fethead

Would it be feasible or beneficial to use TI JFE150 in place of 2SK-209?
I would appreciate an advice as to how this can be achieved (and should it be attempted in the first place).


Thanks.

Windham Hill series, George Winston Piano Solo "Autumn" and "December" vinyl albums. Both records in A/B+ condition, jackets in A condition. New sleeves. Excellent recordings to use a test records or easy listening. I already own each of these, so these are duplicates that came with a collection I just purchased.

Asking $6.00 each and will ship media mail.

Unit has been owned since new in a smoke free environment.
Both units work flawlessly.

Am happy to post at cost, or would prefer to meet mid way to exchange (live in York, happy to meet anywhere near mountain biking).

A real no-compromise solution, the 125M has massive power reserves for fast and accurate transient response and control of most 'difficult' loudspeaker loads. Channel separation is completely perfect - as each channel has it's own dedicated amplifier. An added bonus is the ability to place the 125M very close to each individual loudspeaker, allowing shorter cables and resulting in more precise control.

As with all TAG McLaren Audio power amplifiers, 'Straight Line Technology' provides the shortest, most accurate path for the signal. The benefit is a great sound!



125M Mono Power Amplifier

Digitally-controlled muting
'Straight Line Technology'
Gold-plated phono connectors
Massive toroidal power transformer
Multi-room or multi-zone applications
Proprietary Sorbothane® sonic isolation feet
Signal output to connect to other power amplifiers
Duplicated loudspeaker terminals for bi-wired speaker
125 W per (single channel) into rated load impedance (8 Ω),
200 W into 4 Ω and 275 W into 2 Ω for short periods
This section is for those of you who really want to know the 'insides' of your 125M. You will not miss out on any of the functions or performance of your 125M if you choose not to read any further.
rated output
power 125 W per channel into rated load impedance (8 W)
200 W into 4 W and 275 W into 2 W for short periods
typical output
power 145 W per channel into rated load impedance (8 W)
240 W into 4 W and 320 W into 2 W for short periods
input for full
rated power 1.13 V rms
input
impedence 47 kW nominal
gain 29.0 dB at 1 kHz
signal to noise greater than 96 dB (relative to 0 dbW)
frequency response (-3 dB) 0.1 Hz - 75 kHz
frequency response
(20 Hz - 20 kHz) ± 0.3 dB
total harmonic
distortion + noise less than 0.05%
polarity(phase) non-inverting for all inputs and outputs
operating temperature range 10 - 35oC
ac supply
frequency 50 - 60 Hz
ac supply
voltage 110 -120 V or 220 - 240 V
The voltage is marked on the rear of the unit
power
consumption less than 300 W
dimensions
(including feet,
terminals and controls) 445 mm wide
75 mm high
333 mm deep
We reserve the right to alter design and specification without notice
Specification may vary for different countries

User Manual - http://www.iaguk.co.uk/tag/125m_instructions.pdf




A few reviews:

125M Mono Power Amplifier





"The best S/N ratio we have measured in the last few years."
"The best channel separation measured ever in a line preamplifier."
"The Stereo image is excellent in all dimensions. Music is pleasant,

lyric and realistic."

HXOS (Sound) and Hi-Fi Magazine
"The F3 range-toppers are agile devices. They offer strong imagery, in particular when highlighting differences between alternative recordings. The sound stage contracted and expanded both front-to-back and left-to-right with different productions. Timing was competent, speed impressive.

"If the Audiolab sound appealed to you, then this combination should represent a worthy step up the ladder towards audio Nirvana.

"Build, finish and styling are exemplary."

Hi-Fi Choice

"No miracle, to achieve top class in the listening test the 125Ms required only a few minutes. Then, still in the warm-up laps, they took off - more powerful and more detailed... Whoever questions the musical pedigree of the newly-established design team is wrong. TAG McLaren Audio, with its first products, is already in the fast lane... Top class"

Stereoplay