I'm on another Car Audio forum, but I thought of getting a different feel and opinion from DIYAudio. I like reading about Car Audio and Electronics. I think just reading the article and comments helps me become a better technician. Which is the whole point of me joining a forum. And I'm from Hawai'i.

years ago I remember reading an article by someone who measured the T/S parameters of his 416b in his Altec model 19 and found the factory cabinet was much too large for optimum results. Can anyone refer me to this article? Seems that Altec actually recommend 7.5 cubic feet as the optimum for a 416b but I thought I recalled the previously mentioned article as being somewhat smaller but I am not sure of that. Any assistance would be much appreciated. I have seen reflex designs as small as 7 cu ft in volume. Any Altec owners out there who have shrunk their model 19's with success? Thanks for any input. Best regards Moray James.

Hi all,
I got this magic subwoofer with 6 x 8" elements inside it. It is equipped with 2 amplifiers inside both driving 3 elements each. I took a big risk and bought it defective but it was working at time of bying it. But hearing some noise when powering it up so decides to have a look inside. What i found was 70V dc coming from one of the amp at speaker output, so i measured all the elements coupled to this amp and luckily they looks ok (13.5ohm each).
There is some burnt components on the amp itself and a shorted output IRF4227 between S and D. It is 2 resistors and also a capacitor with signs on it. Should i also replace the driver IC IR2110s or could thisone be measured before putting a new pair of IRF4227 ?

Hi tech guys

I'm seeking some clarity on correct tuning for 416 Altec woofer (reconed by GPA) in new cabinet.

The internal volume is very close to 170 liters.

Cab is double walled and braced. Approx 80Kgs each.

The port is 300mm x 65mm x 80mm deep.

How can I check the tuning of this with the 416 T/S specs?

Altec Thiele-Small Parameters

MantaRay horn with 291 1.4 inch driver.

BTW, the speakers are sounding FANTASTIC...so this is an exercise in theory/checking only.

Cabs finished in lovely two pack poly, grey, with pearlesc additive.

Xover is 750Hz, with LR2 and quality Jantzen silver caps.

With thanks, Andrew.

The LSA Signature 80 speaker is currently in production and should be arriving in the next month or so. I am really happy with how this design turned out. As the designer, of course I think it sounds great. I voiced it for a natural presentation that has clearly resolving highs but is non fatiguing. The midrange is lush and smooth and the chat punch is all there. I figured there will probably be more questions about this speaker as it gets closer to being released for sale by LSA so I am making a dedicated thread for it to provide a forum for questions and answers.

The exterior finish is without question, one fo the best I have seen. The rosewood looks so good, it almost looks unreal. I had to put it under a microscope to see that it is indeed genuine real wood. The craftsmanship is so good, one has to wonder how the cabinet makers can do this sort of thing. I know I can’t get anything like this myself in a wood shop.



Design is 2 way ported reflex (50mm dia vent on the back) with 7in aluminum cone midbass driver and 3in planar tweeter in a custom waveguide. Crossover is at 3.5kHz and uses all high quality film caps and large gauge pure copper wire inductors with audio grade non inductive wire wound flameproof resistors.



Premium Viborg binding posts with carbon fiber accents on custom CNC aluminum plate.



Cabinet is 3/4in MDF and 1.5in thick MDF on front baffle finished in gorgeous genuine rosewood veneer expertly applied with a satin finish coat.

Measured (quasi anechoic near field) frequency response is 38Hz (-6dB) and 22kHz (-3dB). Sensitivity is about 84.5dB at 2.83vrms and 1m. Polar response is uniform within +/-2 dB over 60deg inclusive angle for a wide sweet spot. Time alignment is precise and the soundstage and imaging are superb. The XO was designed to allow an easy to drive 8ohm nominal load (probably closer to 11ohms for most of music).

Here is the predicted speaker electrical impedance:



Here is the frequency response measurement in room (my lab) on a 40in high stand) - disregard response below 150Hz due to room modes, note the measured acoustical phase response and can be seen to be very smooth through the XO region for great imaging:



Have a listen (recorded with iPhone 12 Promax):

Login to view embedded media

I am trying to find an old Fender amp website that I used quite often but now I can't remember the name of it----it had all the history and schematics, pictures, specifications, timeline of various versions, etc. Does anyone recall the site I am talking about? It wasn't an official fender.com website; it wasn't Robinette's site; it was called "Fender amp field guide" or something like that. All I have found is a couple of threads that mentioned it had gone away and then come back again.

Has anyone tried using any of the prefab 12” vented car subwoofer boxes for the Betsy-K? They usually run between 1-2 cuft. Looking for something cheap and easy for a basement system.

Hi!
I have a SVS SB16-Ultra.
When i connect it to a source the only thing thats coming out of it is a flapping sound.
Do anyone have a clue what might be the problem?

I have a pair of Edcor 50W 3.4K push-pull output transformers with 8 ohm secondaries. I believe I may have mounted one of these (I can't tell which one), but I never even cut or soldered the leads. I will sell these for $150 shipped CONUS, which is about half the price for a new pair.

I have recently acquired a dead crown drivecore amp. The two Igbt’s in the psu were exploded, legs blown off! No pcb damage luckily. Also four 10R resistors around the gates got vaporised and two diodes blown short circuit in the gate drive. The markings on the diodes GY63. Google drew a blank. Can't tell if these are Zener’s or fast recovery diodes the resistors and diodes are SMD. The switching transistors are driven through pulse transformers so hopefully no other components in the driver stage damaged. the two transistors to discharge the gates seem to measure ok with a multimeter. does anyone have a schematic of a cdi drivecore amp? i found one on YouTube but it’s rather low res and the owner of the channel want $150 for a pdf copy. I have attached the low rez copy of the relevant page. Can’t make out which are diodes or resistors.

Hello,

I have a few spare boards that I bought to offer the community. These are the F5P and M2 - both V2. Many thanks to Fran and Patrick for the design and layout of these boards. Selling for $16, plus $4 USPS shipping - in the USA only for now.

Please PM with your PayPal ID, and address if interested.

Rick

Edit: Point of clarification... This offer is for a stereo pair of each. 4 PCB in total.
Edit 2: Photo and shipping will be via USPS Ground Advantage.

Hi fellow forumers
I'm going to restore this amp for a friend of mine
this is the unit: AM-240 Ampl/Mixer Olson Radio Corporation; Akron, Ohio, buil
Obviously, the one I've in the bench is not in such a good shape, take a look:
Well, lacking the schematic the restoring job, while not impossible, becomes considerable more difficult. So If one good soul can share the circuit, it will help in an just and heroic cause.
Cheers
J.

One only: Black anodized rack mount case size 17 x 12 x 3 in.
Price $30. plus shipping and PayPal charges. Ship via Canada Post or UPS.
Sorry, unable to post a picture due to the size being too big,

I have an Ion Obelisk which as a fault where the output is lower on one side, I've checked the psu voltage to the poweramp which +60v however the voltage on the positive side of C1 is 21v on one side ( which if im reading the schematic correctly is correct) and only 9v on the other.

Any pointers on where to look?

Hello. I am in the construction of full range speakers.
I would like to try the Markaudio drivers.
Looking at the box plans that Markaudio suggests, I see that it mentions required resistance for the cables from the amplifier to the speaker and for example "high output impedance amplifiers".
I do not understand what you're referring to.
I have a Marantz PM6006. Will it be appropriate?
I ask before getting into the construction of the speaker.
Thank you

Hello, let me start with I picked up this nice condition JVC receiver because it hosts a 130w per channel amplifier. However when I start turn the volume up and I get to an almost perfect level of "loud" but not "distorting" (it's not even nearing distortion, so I can tell there is still lots of room for more volume...) but when I pump it up a bit more the over current protection kicks in. (I have about 14 other receivers here all around 100w to 110w and they all drive these same speakers much louder with more punch).
I can tell whoever set this protection circuit up must have leaned towards safety over performance, because the heatsinks are not even hot.

I opened it up and I thought I saw "temperature sensors" thermistor's near the amp chips, with the "left channel" one being bent very close to the amp IC (I bent it back like the others) and I assumed ok now I'll get more volume. But I got the same cut out at around the exact same volume. So I installed a large PC fan on the heatsink to keep it cool... and it cut off at the same volume (I might add this is not digital/display volume on the unit - but the same audible volume).

So there is something causing the cut off to cut out long before it's technical abilities are overloaded/tapped.
I'd like to figure out where the over-current protection circuit might be, and possibly remove it and or change it's value so it does not cut out so soon before the peak performance of this unit has had a chance.

I might add some key points:
The speakers I am using are in A+B combination (4 speakers) / the unit states in the manual use only 8 or 16ohm speakers at each terminal, however both pairs of my speakers being used are 4ohms. Technically speaking I get away with using these same speakers on other receivers fine (making sure to always use a good fan to keep the heatsink cool) and there is no issue driving them hard for extended periods. I have one Sony 110w which only has Speaker A terminals and it's got a hard switch to select 4ohm or 8ohm, so I set it to 4ohm and installed the 2x 4ohm speakers totalling 2ohms and ran it for 10mins, the heatsink got so hot I panicked and installed a permanent fan. Now it runs fine 2ohm speakers testing for a solid hour at loud volume, no issues (and stays just warm now).
So out of all these other receivers I've run these same speakers off - this is the only unit having "issues" and I think it's simply because they set the cut off limit too low.

I've included some images, in the one image I have two arrows, the Red Arrow points to a trimmer that is on only found on the L / R channels amp boards. Judging from the type of wires running to these pcb's I'm assuming these pot/trimmers are a "line input levels" (for gain up or down). However I'm not sure how these circuits were designed, and more importantly what an over-current circuit looks like (and or where they would locate it) so these might also be the "cut off voltage trimmers?" I dunno hence why I am posting here.

I've also included a potential "sectioned out pcb" that looks like it might be regulating the voltage... so perhaps this is the over current circuit?

But lastly, I also marked a "yellow arrow" to what I originally thought was temperature sensors doing the cut off....(it looks an awful like a Thermistor to me) AND the PCB label for this part is literally "TH731" further indicating it's "THermal" sensor, so perhaps I can just swap these out with another value? Or put a resistor in their place? But what value... hmmm.

Any help would be greatly appreciated!

Recently acquired an HK Citation11 & 12 pair from the mid 70's. I noticed a 1K resistor across 2 of the 4 caps in the PS of the HK12 that does NOT appear in any schematic nor on the parts list of the HK12. Has anyone found this in an HK12? Anyone know why HK or someone would install such a resistor?

I used this sub a few times in the early 10 - 12 years I owned it. Divorce time my ex and her friend werent very careful loading it into my pile, so no chance of selling due to chips and surface scratches. Used it in an early iteration sound system here, until I went to OB and V instead of P wave bass. Been down in the garage ever since, never hooked it up to the system there. Sooo,, rather than build a new construction -




I glued the two back pieces in place, where the rear aperture ends up vertical. Cut to save the original radius. Size is basically the ample shelf space the amp chassis needed on top. I'll probably fill the notch, as I have plenty of wood there left over.

Handle on top, some rubber feet for the bottom. Coat of paint - wish I had the paintable tolex stuff on hand - and should look fine for me. I have the round grille for the front, held in place by Velcro. Granted, it's a lot heavier than a pine board enclosure....

Got a working 12" sub driver and plate amp, if anyone's interested! ;')

Hi I am a new member of the forum, I hope i am in the correct part of the forum
I have an Allen and Heath ZED 428 analog mixer that i use for my small home recording unit
The mixer has a problem on 1 channel so its not a major problem,
if the eq button is pressed to activate the eq then the sound disappears, when i press again the sound is back
So on this channel i have no control of the eq
I have some experience of repairing various Analog audio "things"
I intend to open up the mixer and remove the channel and see if i can repair it
Any help with this would be great! (drawings ?)
Regards James

I have a bunch of 6AS7G I thinking of building with in the future.
But I wonder do they sound best I SE or P-P?
Nevermind the outputpower just the sound Quality.
Schemas are welcome..

The sound from the right channel of my Sherwood SEL-400 amp dropped out suddenly and had a "hissy" fit, no smoke but I did smell something cooking when I opened up the amp and noticed that a very faint smell seemed to come from the Right channel output transistors.

The schematic indicates that output the transistors are SJ1936 & SJ1937, these are present in the Left Channel and they each have a "blue dot".

The Right Channel has Motorola SJ1902 & Texas Instrument SJ1903 which are obviously replacements so the amp must have had this problem before.

I pulled the outputs to test them and this is what the PEAK Atlas showed. (Three of them read what is indicated with an asterik*, the fourth does not). My guess is that the Right Channel transistor Texas Instrument SJ1903 is faulty since it is the odd man out. Can someone please confirm this?

Right Channel:

Motorola SJ1902

NPN Darlington Transistor
*Diode Protection between C-E
*Resistor Shunt between B-E
*hfe not accurate due to B-E res
Current gain hfe=27
Test Current Ic=2.50mA
Base-Emitter V Vbe=0.860V
Test Current Ib=4.096mA
Leakage Current Ic=0.000mA

Texas Instrument SJ1903

PNP Darlington Transistor
Current gain hfe=34
Test Current Ic=2.50mA
Base-Emitter V Vbe=1.172V
Test Current Ib=3.785mA
Leakage Current Ic=0.000mA



Left Channel:

Motorola SJ1936

NPN Darlington Transistor
*Diode Protection between C-E
*Resistor Shunt between B-E
*hfe not accurate due to B-E res
Current gain hfe=22
Test Current Ic=2.50mA
Base-Emitter V Vbe=0.807V
Test Current Ib=4.148mA
Leakage Current Ic=0.000mA

Motorola SJ1937

PNP Darlington Transistor
*Diode Protection between C-E
*Resistor Shunt between B-E
*hfe not accurate due to B-E res
Current gain hfe=23
Test Current Ic=2.50mA
Base-Emitter V Vbe=0.841V
Test Current Ib=4.113mA
Leakage Current Ic=0.000mA

Hi diyers,
I would like to submit this project for a mid-bass transmission line to you. I kindly ask for your help in identifying any errors or improvements.
The desired result was approximately 40-500hz bandwidth and the woofer selected was the Volt RV3143.
I tried to model the line with the Hornresp SW, these are the parameters used:

• TL section: 800cm^2
• TL length: 203cm
• speaker offset: 60cm
• section filling: 60% short part, 10% long part

The only way I found to replicate the upward extension declared in the speaker graph was to "cheat" on the Le parameter, lowering it quite a bit, but maybe I did something stupid.
I attach some screenshots, and thanks in advance for any help.

Hi all,

What CAD software are you all using to design your chassis?
It's time to put this thing in the casing it deserves.
Thanks and Cheers!

Ruben

Hello, im currently planning a build and thought i would "steal" the ldvor TPS7A4700 regulator and make my own, it wasnt really rocketsience, i just looked at the BOM and at the official datasheet...

What do you think what's a useful infrasonic extension for home theatre? I loved chasing single digit extension but I'm not so sure anymore.

I had the Bag End Infrasub18 that played 8Hz. It sounded nice although only at very low levels.
I built a dual RCF LF18N405 450L ported subwoofer tuned @15hz in my hobby room. This one still puts a smile on my face when played at higher levels.

The problem is this though:

I built a dual B&C 21SW152-8 540L ported subwoofer tuned @11Hz in my living room and I also have a quad Visaton 15" TIW400 sealed subwoofer in there. I did some measurements and the sealed sub quickly drops off under 30Hz. Both ported subs also have a gap between their tuning frequency and the first room mode and I feel that both subs together fall a bit short around 20Hz without EQ. Also the movies with 10Hz content are rare.

I'm thinking of raising the port tuning of the B&C to 15Hz and also rebuild the sealed sub into a ported one also tuned at 15Hz. This way GD only starts to rise under 20Hz so music still sounds tight? The (still low) tuning frequency will also prevent the woofers from over-excursion below tuning?

Your thoughts?

Hi friends
I need your help regarding upgrading my opamps in my mark levinson 33H
All the modifications that I have made to those amps gives them a new life and the sound became more analog.

However my question is divided for 2 parts:

1. The first part since those 33H has few revisions the earliest version uses AD705 and later version uses OPA277P
I have contact Harman group and they say that instead of the AD705 they use LT1097
I have compere the specs of the OPA277P vs LT1097 and I see any reason why to use LT1097 since the OPA277P is better by all means.
Did I miss something???

2. The second question related to the oscillator board of this amp
Since this amp has an AC regenerator for the input stage.
The oscillator uses NE555N and this connected to a series 3 opamps AD712JN
I was thinking to upgrading those opamps
To an opamps that have better specs of noise rejection to have better cleaner AC
Instead of the AD712JN I saw 2 options
OPA2134
OPA1642
The 1642 has better specs and is much faster than the 2134 and I'm afraid of oscillating problems.
Since I'm not expert in electronics
Please help me to to decide what to do in this case
I'm looking for direct replacement
If you think of better opamps and more suitable please let me know
God bless you all
Thank you

Perhaps I originally posted this question in the wrong forum since I have received no replies. Yamaha receiver, RX V3000, no audio from left channel when using digital/optical input. Analog/RCA inputs work as they should, provide sound from both channels. Different digital cables give the same result. Input is set properly. Burr Brown DACs, 1704. Do these tank over time or could there be another issue? Where do I begin to trouble shoot? I have compared multimeter readings from one good identical Yamaha DSP board to the one in question, and all appears to be consistent. I am stumped. Any ideas?

How to make a tweeter measurement using software ARTA, example from 500hz? In STEPS you can set the measurement frequency, but in ARTA I couldn't find where.

Just want one board, condition is unimportant so long as the 1794 chips are good.

What is going on with the Hoffman Amps website? When I tried to access it today, I got a VERY LOUD warning that it contained a Trojan virus!! I have Norton anti-virus on my computer. Anyone else experience this?

Interested in Nilai, either stereo or monoblocks. Would pay 900 shipped for the stereo, or 1100 for the monos assuming good condition. Let me know, thanks!

Can anyone here help me by deciphering the value on this tiny device which I thought was a capacitor?
Thank you!

Hi
I've got 2 IMF, 3021 GT 03, I think they were made by Elac, woofers, used in the TL Range, they are in good condition, can provide DAT v3 data.
I used them for a while in a diy tl speaker, but decided to build a new set up, so no longer needed.
Price 125 Euro each, when bought together, total 225 Euro, shipping must be payed by buyer.
Cheers, Tom.

I clone the above in mono block. Recently the right mono block B+ shot above 1000V. As a result the tube was damaged. The B+ used be about 955V. My Left mono block is still working.
I would like to know the reasons for the B+ to shoot up. Thanks

This is a bass preamp , basically cloning a Gallien-Krueger Fusion 500 tone section . It has a 300 volt B+ feeding two 12ax7s driving active Lo-Mid , Hi-Mid , Bass and Treble controls. The power supply is one I developed from a flash-gun circuit I found online and a little 18mm flyback transformer from an old flashgun along with a 2sc4834 transistor , two polarised caps and a resistor and a couple of diodes. The 2sc4834 was chosen because it seems to have a high power-handling capability , so would be less likely to overheat , I don't know enough about transistors to make a more knowledgeable pick. For so simple a setup it performs remarkably well , I have a voltage regulator taking the 9v wall-wart input down to 6.3 volts and that feeds the heaters and the psu. I used an LD1085 regulator but it does seem to heat up more than others I have used so I would change it next time. The transformer is wound to produce 300 -odd volts from 6v battery supply in the flashgun , so with 6.3v it produces around 320 volts , I had to put a dropping resistor in . (I suspect it could go quite a bit higher if needed) . The voltage on the plates is about 202 v which is close to the G-K schematic. There's no sag I can see or hear , and the waveform of the AC ouput looks reasonable to one who knows very little about these things , the DC doesn't have a measurable ripple on my little handheld oscilloscope , but I'm new to all this and someone with better knowledge and equipment would be better placed to know if that was so. The preamp is quiet , on a frequency analyser the only sign of the switching power is a very tiny peak , mostly below -110db , which comes and goes for reasons I haven't found yet , I think it's probably emitted radiation from the transformer and I've done some shielding but perhaps it needs better. The peak and the switching is at 11kHz , which is far enough above the range of a bass guitar to not interfere , and at least to my ears there is no distortion anywhere (old ears , mind you).
The main problem with making and improving this psu is the fact that most of the flashguns I have taken apart to get more transformers use either smaller ones in the more modern versions and larger ones in the really old style. It seems that with this particular circuit the sweet spot for transformer size is around 18-20mm , to get a high enough frequency and a steady current supply. I have bumped the frequency up towards 20khz but got much more heat than I was happy with from the transistor, and above that it gets very jumpy. (I thought about winding my own and twice sent off for ferrite cores and bobbins from China , both times just got a load of broken ferrite bits in a bag with no bubble-wrap or anything to protect them.) I keep foraging them when I see a job-lot of old guns on the Bay , and one day I'll find which ones have the right size.
The circuit is minimal to say the least , it's possible that someone with more understanding could create a more sophisticated one that could utilize the more easily found smaller transformers , perhaps switching at a higher frequency. And I have learned that if there is noise , there are ways of implementing snubbers before the transformer , but they require pretty complex maths and knowledge of the transformer specs I think.
I had another valve in there at one point , another 12ax7 as an overdrive valve , and it worked fine , but the voltage regulator started to get more than a bit hot supplying the extra heater current so I took it out - I wasn't aware of the transformer having issues with the extra power however.
The resistor size depends on the inductance of the transformer and the target frequency. The multimeter resistance of the windings is about 0.5 ohms for the input winding and the flyback winding , and varies between 150ohms and 350ohms for the output HV winding on different transformers.
In the pictures the psu is crammed into a yellow box at the end , that's because the initial project was "Can I get a valve preamp into a Coleman's Mustard tin?".. the answer was "No" but the psu fitted into the lid OK.
The first frequency trace is with the bass pugged in, no sound, the second with a string plucked and the peak showing bottom right . It appears for maybe twenty seconds then disappears for a few minutes , there's no audilble change to my ears.
The controls on the preamp are : top , bypass switch and Volume control -: front , 3 way switch to alter the bypass cap on the first triode , (no bypass/10uf/ resistor and small cap.) , switch to add "Deep" to low-mid control , Hi-Mid , Low-Mid , Bass , Treble , input and output jacks.

The Clio seems like an easier system but it’s twice the price.
Which do you recommend?

LOCAL PICKUP ONLY. NO EXCEPTIONS. Costa Mesa, CA

I have a pair of what appear to be 4 Ohm Apogee Scintillas that are in need of full restoration. My goal here was to follow in AVWERK's footsteps and make this a fun DIY project. I just don't have the time.

I have the following:

1. Pair of beat up Scintillas. They were stored outside by previous owner, they will need full disassembly, cleaning, probably new wood just about everywhere. Crossovers, stands, terminal plates, everything included. Removable covers have warping from water damage. They used to smell like cigarette smoke as well but I've had them in my garage for over a year now and I think that is mostly gone. All ribbons damaged. They stand vertical and look good from afar 😉

2. Roll of wide kapton tape (this wasn't cheap. Sourced on eBay from international seller). 0.025mm x 500MM x 33meters Amber Polyimide Kapton Film With Adhesive Single Side

3. Roll of foil (from Grainger) : Aluminum Foil Roll: 1100, 18 in Overall Wd, 50 ft Roll Lg, 0.001 in Thick, Mill, Full Hard

4. Parts to build corrugation device per AVWERK. This was tough to source, got it from a 4x4 truck parts shop.

The rest is up to you. AVWERK has a great thread in the exotic speaker forum here you can try to follow along.

Asking $1,500 for everything. Must come collect. Just want to recoup my costs. If you're up for a fun project the sky is the limit here 🙂

Please do not do the following:
1. Send me a message to kick the tires.
2. Send me a message to ask about how to go about the project. This is a DIY effort, do your own research
3. Send me a message asking if they are available - I will update this post when they are gone.
4. No pictures - don't ask.

I feel for the price this is a win-win. Price is firm - cash only.

Hello '
I custom hand build single and push pull types of Tube preamplifiers to Intigrated Amplifier's with output tubes ,using El34, KT120, El84 for push pull types out put wattage rated at 10 to 275 watts RMS. And 211 ,845 for the single ended Intigrated amplifier s preamp stages using 12AX7, 12AT7,12AU7 , E188cc types the electronic components are sourced from the best brands all point to point soldering and some with tag pcb soldering.you could email me ' or WhatsApp me on +94777145436

Put it to test how good or bad your expensive speakers are , around 05:00min :

Login to view embedded media (video in german sorry but you can switch to english in the settings , a bit tricky but works!)

Of course how strong the reaction of your speakers are , depends largely on the music you are using for this test! Use the normal playback level or somewhat higher to get a realistic impression of the unwanted noise that disturbs your high fidelity ambitions!

Easy to be done , takes no additional stuff , just some curiousity what's going on in your sound field during listening?

Why hasn't it be done as a standard test way back in history?

My suspicion is - most people fear to know how bad their speakers really are!

No excuse no more - kill all those sound devils that deceives you and take all your money , burning it in hell to torture those sinners down there 🙂

regards - death to all bad cabs 🙂

ps .. using pink noise for testing makes more sense and can be analysed to get a FR graph ...

I've had this 1979 amp and preamp pair for several years now, and I've often wondered if i can replace the near prehistoric "stereo preamplifier" ic with a modern opamp.

It sure looks to me like a dual opamp with external compensation and offset zeroing, but the datasheet is less detailed than we expect these days. For example, it says it has a differential amplifier, and does not specify which input is inverting or noninverting.

I've attempted to draw a simplified schematic, using an ne5534 as a stand-in for 1/2 of the ha1452w, and without the rest of the preamplifier input (a jfet pair) or the tone controls, etc.

Does this make sense to anyone?

I attempted to air-wire an adapter to an njm2068L but this just results in a hum at the output.

Currently fitting some ceiling speakers in my kitchen running to a TPA3118 based amplifier - all good on that side.

What I need is a receiver/device of some sort that will appear as a "Speaker" on an Apple device/Apple Music (so supports Airplay) and can stream from an Android from - generally from Spotify.

I could go down the Bluetooth route but I'd rather not as it would be good not to have to be a close distance to the receiver all the time.

I've got the hardware to setup an RPi Volumio install (Pi + DAC) (or PC + USB DAC) but that felt a little like overkill for this application.
Doesn't need to be Audiophile standard as the setup as a whole isn't.

Some devices I've seen - are they actually any good? Or a waste of money?

Audiocast M5
Wireless Receiver WR320
Arylic S10
IEAST Audiocast Pro M50

Needs to be a "Just Works" solution with good WAF.

Hi! first, english is not my main language, im a complete noob in electronics, i realy like to build mi own in ear earphones amplifier, here is my problem:

3.5mm out from a multifx processor (nux mg30) guitar pedalboard --> to a "custom" earphone (only one earphone "speaker", i recycled only one earphone from a bluethoot set and wired it to a 3.5 mm stereo jack (but it's only 1 earphone so it could be mono)

PROBLEM: master output from multifx controls both volumes: guitar outuput and earphone level.
i need independant earphone volume control, i built a passive one (it's basically a 10k logaritmic pot), but it doen't have enough volume at maximum level, i think i need an active volume control for this (an amplifier)

what's the easy and cheap way out of this? what can i build??
i've read multiple threads here, but i dont seem to find what i need since everyone is talking about "HEADphones" not earphones, i think this may be a major difference

As seen at BAF 2022!

Amazing one-of-a-kind live edge dipole loudspeaker pair made from solid slabs of Maple. Hand-crafted (by me) in the San Francisco Bay Area.

These speakers have a huge soundstage, great imaging, and high degree of overall realism. Few speakers outperform these.

This is a bargain: I am selling these at less than the material cost in order to fund (and make room for) further developments. Honestly, these are one of the best speakers I have ever made and will be sad to see them go. Unfortunately, the Eton Arcosia drivers have become difficult to source so I no longer make these.

I consider these demo/prototype units. There are some imperfections in the finish, but that adds to the rustic look. From the listening position, these are stunning to look at and hear.

Come audition in the SF Bay Area, California. Due to their size, I would prefer to sell locally. Shipping would need to be freight at the buyer's expense.

Message me on DIYAudio or buy on US Audiomart: https://www.usaudiomart.com/details...-baffle-loudspeakers-pair-demoprototype-unit/

Details: http://natursound.com/spirit.html

Drivers for sale! Make me an offer! All four are working properly. I just removed them today from a DIY speaker I purchased many years ago. I’d like them to find a new home!

Decided that in fairness to the THD, s/n thread the IG-18 should be discussed on its own.

I modified this IG-5218 a long time ago -- looks like it's in need of modding again --

Selling a pair of hemp acoustic full range drivers. I tried using them in a project and decided to go with a horn setup instead.

150 for the pair.

Up to now, I always had single primary power transformer, thus I am a little discomorted.

Here’s this little xformer, dual primaries, where the dots are on the outer pins.

To make it a 230V transformer, I bridge the outer Pin (dot) with the inner pin (no dot) of the other primary, correct?

Is there a method to measure/test it without connecting it?

Thank you all!

I have been looking everywhere but there has to be some sort of guide or tutorial?
How do you design a crossover from measurements?

Hello All

I have been repairing Klipsch subwoofer amps for about 15 years as a hobby. I have decided to start blogging my repairs and eventually do videos of each one. This thread is intended to be a blog and a resource for information. I will try to answer repair questions as best I can. Comments and tips are also welcome, If you do not have the experience or the tools, PLEASE do not attempt any of these repairs. You will only end up damaging the board and it will end up costing more for a tech to repair the damage. If you do not have a high quality vacuum desoldering station (Hakko or Weller) and a current limited mains supply, you should not be working on these amps. These subwoofers do not have any user serviceable parts inside. If you open up the sub or attempt any repair you see in this thread, you are doing so at your own risk!!!



The main issue that I see with these is a thermal failure. The parts were placed too close together and since almost everyone is too lazy to switch them off when not using them the capacitors just cook and then things start to burn up.



ALWAYS REMEMBER TO UNPLUG OR SWITCH OFF YOUR AMPS. CAPACITORS HAVE A LIFESPAN AND WHEN POWER IS APPLIED THE CLOCK IS TICKING. THE AUTO ON/OFF FUNCTION DOES NOT PREVENT THIS ON MOST MODELS!!!!!!!

Looking for two balanced - unbal transformers for the input stage of a tube project

Bonjour à tous,

Je vous propose pour analyse ce préamplificateur de ligne, construit avec AOP OPA1611.
L’entrée XLR a un gain de 1, l’entrée RCA a un gain de 2 pour éviter d’avoir une différence de volume lors du passage de RCA <=> XLR.
Les deux interrupteurs sont en fait des relais. Je vais ajouter un relais pour commuter les masses, ce n’est pas sur le schéma.
Puis un potentiomètre de volume 10k et un buffer OAP.
La résistance R21 simule la charge.

Qu’en penses-tu?

Merci pour vos critiques constructives.

Alain

I am looking at getting some Tannoy Autograph Mini drivers for £250 and want to build or buy and reuse some good sounding cabinets, crossovers that filter the original signal at 2.3khz, a low frequency and a high frequency amp.

I need suggestions on where to get suitable cabinets or designs to build; crossovers, HF amp and LF amps or recommendations on where to get them as either kits or pre-builtI. I am looking for suggestions and opinions.

Thanks,
Philip

I have a Russian tube that looks like it might be a dual pentode in a 9-pin package, with a husky pentode and what looks to be a lower power pentode. the number looks like it might be 6P4P, though I'm not sure about the cyrillic character at the end. Does this ring a bell with anyone?

Hi,

I am building a Chinese kit for a friend, I have no experience with tubes or audio so this is quite challenging to debug.
This is almost the same kit that my friend got

https://www.fyfaudio.com/products/h...amplifier-marantz-m7-circuit?VariantsId=10237

The wiring diagram is not very clear but I managed to understand the connections, it doesn't work, the output volume is very low.



I measured all the voltages (top caps and pin 1,6, 3 and 8 of tubes) and are within a 10% range of the values of the schematic above, what would you think is wrong?
it seems that is rated 30W, I am using a 6ohm 10W speakers, audio is very low, doesn't sound distorted to me
Thanks

Hello all,

Recently I have taken an interest in studying diffraction's effects on loudspeaker response, after reviewing Gedlee's whitepapers. Gedlee's research shows that linear distortion artifacts of diffraction are highly audible, more so than non-linear distortion. On the full-range thread I studied the correlation between full range polar response in relation to speaker diameter. This was an effort to use driver beaming to reduce the frequency bandwidth effected by diffraction loss. In summary, you can not practically eliminate all diffraction related distortions by using high directivity fullrange drivers on maximally small baffles. ...but what about creating a speaker that effectively has no baffle step, because the baffle is so large that it loads all frequencies equally?

I've recently taken interest in the design behind Stereophile's A rated Devore Fidelity Orangutan O/96. It's a pretty unusual speaker in that it uses a wide baffle, against the current grain of "tall and skinny" loudspeaker design. Going over reviews on the internet, I came across an interesting tidbit behind the engineering of the O/96. John DeVore states,

"... It eliminates what a lot of people call the step response. Which is where the speaker goes from broadcasting its sound[wave] forward in a hemisphere because the baffle has a certain width, to broadcasting into the room as a sphere because the sound wave becomes double the width of the front baffle, and generally speaking, at that point, whatever frequency that is, the power response in the room will drop...

Hide the fact that there is a baffle by moving the speaker close to a wall boundary so that the wall boundary essentially catches what’s left and everything is coming forward in a hemisphere no matter what the frequency. The other way to do it is to move the frequency so that the step response happens by changing the dimensions of the front baffle, and that’s what we did with the ’96."

Some simple math can show exactly what he is talking about here.



"When a loudspeaker produces a sound, this sound is in the form of a pressure wave trying to expand equally in all directions spherically (like the balloon analogy). The first obstacle that this wave encounters is the baffle face itself. For higher frequencies with shorter wavelengths where the baffle is acoustically large, the baffle causes a doubling of axial pressure into the forward hemisphere (since the pressure can’t expand spherically), much like a perfect reflector. This doubling of acoustic pressure produces a +6dB gain on axis in the forward hemisphere. A baffle with a width of about 9” would correspond to one wavelength at about 1500Hz, this +6dB gain would then be seen at frequencies above 750Hz (that half-wavelength rule)." - Salk Sound

The O/96 utilizes a 18" baffle. 18" would create a baffle step at 376Hz. The wavelength of 376Hz is exactly 3 feet.

Thus, if a speaker with an 18" baffle was 3 feet or closer to the wall behind the speaker, the baffle will appear acoustically infinite - no baffle step. 😱 \

So, why not invent a driver made out of Aerogel 🧐 thoughts someone?

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The stuff that keep me awake at night 😑

FET 237 blown ,D198 also blown along with one of the rail caps.I remove all bad parts but did not replace none.I see oscillation on the outputs but am not getting no audio output.

Any suggestions?

I am designing a PCB for a tube compressor with a max gain of about 40dB

The heater supply requirements is 6.3V 1.6A. Initially I thought to make it DC regulated, but the power transformer gets too big for the chassis I'm using.

I am wondering if there is a way to run the AC heaters on the PCB without causing too much noise.

Perhaps running the connections on the edge of the pcb away from grid circuits would be safe enough, or maybe some kind of heater elevation would help ?

I am seeing a few diy projects that run the heaters with the classic twisted pair off board but I am also seeing commercial units that seemingly run the heaters AC on the PCB. So I guess in some way it's possible.

Wondering if someone has any experience with this.

Selling my 12" Rega R200 special.

This uses a nice custom made heavyweight SS tube with SME3012 geometry.

Custom armbase for adjustable VTA.
Extra heavy SS counterweight.

Fitted out with Cardas din standard phono connector.

Rewired with Litz silver tonearm wire.

(No Rega anti-skate function - not required for 12" arm)

Suits low compliance cartridges.

£170 plus postage, or collect free (UK based)

I hope that this could be of interest for you.

I constructed the Cyburgs-Needle originally for Visaton FRS8, which is a nice and cheap fullrange driver here in Europe. The Needle was quite a sucess here, I know of about 20 pairs built by DIYers, and there may be even more. However, I have been looking for an alternative driver to make a "High-End" version of the Needle. I tested several different 8cm drivers, and the Tangband W3-871S finally did it. Unlike the FRS8, you need a notch filter, the values you will find in the plan.
I think that the availability of the Tangband is better outside of Europe, so I hope you will have fun with this plan.

Nice greetings, Berndt

Hi DIY
Could you please advise me, I'm looking to find a manufacturer
who could make me custom high end Permalloy with 80% nickel transformers.
Anyone?
Thank you!
best regards

I built this preamp to experiment with Academy Audio's Muses control and I loved it so much I built a bigger one with their BIB and BOB with the Waynes board.

I am selling this one as it is not getting any use and I need to fund some other projects. Below is a rundown of the parts I used:

• Galaxy 1U silver chassis with 4mm faceplate
• Academy Audio LPS9 regulator
• Academy Audio VCX (older model)
• Waynes Preamp with quality precision resistors
• Blue illuminated vandall push button switch.

Unit has two inputs, two rca outputs, Headphone switching jack, the remote, and runs off a 5V Meanwell Wall Wart recommended by Academy Audio.

I am asking $350 and I will ship it for free anywhere to the continental US.

For sale is a Jolida JD102CRC integrated amp. The unit is near mint, it’s just missing the remote. I do have the original box.

Electroharmonix 12AT7 and EL84 tubes
Tung Sol 12AX7

Asking $400 and I’ll cover half the cost of shipping anywhere in Conus.

I can ship in the original box.



.

Selling one of my F4 amps. I have two other f4’s I use as monoblocks so no longer need this one.

Amp details:

• deluxe 4U 300m iron chassis, black faceplate
• Mark Johnson’s soft start with push button switch
• Pass Front End boards
• switches for RCA or XLR input.
• silver coated wiring and metal foil speaker output wire
• genuine matched Toshiba JFets and matched Mosfets from Diyaudio store

Asking $900 and I’ll ship for free anywhere in the continental US.

Picture shows amp under a Wayne’s Preamp and Pearl 2. The Wayne’s is still for sale but the Pearl 2 no longer is available.

This is for anybody that is in Charlotte, NC and is interested ..

Experience the Revolution in Guitar Sound at the North Carolina Science Festival!
Showcasing SiC Jfet Event with Dr. Mike Mazzola and Dr. Jim Gafford!

Dr Mike Mazzola was the chief technology officer of Semisouth Laboratories when they developed the Static Induction Transistor(SIT) for Nelson Pass at First Watt. Dr Jim Gafford is an Electrical Engineer professor at UNC Charlotte and has developed SiC Jfet to work in Vacuum tube applications.

Join us at Discovery Place Science, located at 168 W 6th St, Charlotte, NC 28202, on April 21, 2024, from 11 AM to 4 PM for a groundbreaking showcase where tradition meets innovation in the world of electric guitar amplifiers. Dr. Jim Gafford and Dr. Mike Mazzola, along with unveils a pioneering transistor that mirrors the beloved qualities of the classic vacuum tube. This exclusive event offers you the rare opportunity to play and compare guitars equipped with traditional tubes and the revolutionary SiC Jfets.
Mark Your Calendars for April 21, 2024, from 11 AM to 4 PM! Dive into the future of guitar sound, explore the crisp, warm tones of the SiC Jfets, and see how they stack up against the classic tube amps. Whether you're a professional musician, a hobbyist, or simply a fan of great sound, this is an event you don't want to miss at the North Carolina Science Festival!
Come Hear the Difference - Feel the Revolution in Sound at Discovery Place Science!

Discovery Place Science
NC SCIFEST

Ok, in the pursuit of a "less-colored" signal path I realized I could remove the grid stopper resistor between my DAC and my preamp as shown on the left side of the diagram below. This made a huge improvement and have had no issues after doing this. When I eliminate the 3k grid stopper resistor between my preamp and amp though, I get weird hums/buzzes/cable noise and all kinds of other weird behavior and get varying levels of hum from lots to none based on cable proximity and position (very werid). If I do put the 3k grid stopper resistor in on the amp these issues go away but the problem is that it sounds SO much better without the grid stopper resistor. I have tried several different resistor types (Audio Note tantalum and Naked Vishay) and it always sounds better without it.

I have two questions:

• Why is the grid stopper needed between the pre-amp and amp and NOT in between my DAC and the preamp? What is different? Is it the output impedance to shunt resistor relationship? There is also a 1M rca cable of the same type between the DAC and preamp.
• Would changing the value of the 1M shunt resistor on the amp solve the hum/noise/strangeness problems and allow me not to use a grid stopper resistor?

Huge thanks,
Brett

Here already are two threads regarded similar subjects concerning newer generations of solid state devices:
1) a. http://www.diyaudio.com/forums/soli...-models-quasi-complementary-power-output.html
1) b. http://www.diyaudio.com/forums/solid-state/162142-tip3055-2n3055-based-power-amps-3.html
2) http://www.diyaudio.com/forums/soli...st-complementary-ab-bipolar-amplifiers-5.html

But now I want to know the first generation high quality solid state comercial audio devices (radios, car-radios, home receivers, preamps, integrated amps and power amps for home-audio, studio/stage/instrumental-monitoring and public address) - independend, whether there is OTL or not so as complementary output stages or not.
Therefore I have create a URL collection about a wide range of "First Generation" transistor types - mainly from central Europe, USA and Japan. A wide range of photos you will find here.
With help of this it is more easy to discover the first model numbers and brands from audio devices in the aera between 1955 - 1965. But please note - because in the transition time most audio devices are a long time still equipped with tubes, at least here in Germany, there are not a wide range of solid state amplifier components.
If anybody is owner of a collection of the magazine mentioned there
http://www.diyaudio.com/forums/soli...sen-jikken-yearly-index-1924-2009-wanted.html
it is easy to find out some models and brands from that aera.
Thank you very much for your advices.

Basic Informations about History and Theory of Operation
First-Hand:Beginning of the Silicon Age - GHN
www.vintagetransistors.com
PNP-Transistor

NKT (newmarket) series
Mister Transistor's Historic Semiconductors

Power Devices from GDR
KHB-Radios -
KHB-Radios -

Collections of various Vintage "first Generation" Types, mostly Germanium, low and medium power devices:
Transistor History (Transistor History)
Raytheon Part Two (Transistor History)
USA Transistors (Transistor History)
Philips (Transistor History)
History of AWV (Transistor History)
http://groups.google.com/group/ham_radio_bulletin/web/oude-onderdelen-onder-de-microscoop?version=5
Germanium-Transistoren und -Dioden
Wumpus. Transistors
Wumpus. Transistors
Vintage Transistors & Diodes
Brand History (short form)
Transistor Museum Early Germanium Power Transistor History by Joe Knight Clevite Transistor Products
Transistor Museum Construction Projects Point Contact Germanium Western Electric Vintage Historic Semiconductors Photos Alloy Junction Oral History
Transistor Museum Photo Gallery Motorola Germanium Power Transistor Prototype
Transistor Museum Photo Gallery Raytheon CK705 Historic Germanium Diode
Transistor Museum Early Germanium Power Transistor History by Joe Knight TI Page 5
Transistor Museum Photo Gallery Raytheon CK793 Silicon Alloy Junction
Transistor Museum Photo Gallery CBS 2N155 Germanium Alloy Junction Power Transistor
ABQ-Techzonics Transistors - Bipolar MOSFET,FET,IGBT (Gallery - for vintage part scroll down)

Collection for use by Telefone
Transistor

Transistor History 101 by Bob McGarrah
Transistor History 101

Raytheon first transistors designd by Mr. Frank Dukat
next

THE CK722 CLASSIC GERMANIUM TRANSISTOR MUSEUM
CK722 Classic Germanium Transistor Website and Museum Photo Gallery Photograph Page6

EARLY TRANSISTOR HISTORY AT RCA
RCA Transistor Oral History Kalish Index
50 YEARS of the CK722
CK722 Germanium Transistor Construction Projects New Volume Index

First Generation of Japan Transistors:
Hitachi Transistor
TransistorArchive: ???????????????? ?????
TransistorArchive: ????FUJITSU ?????
TransistorArchive: ???TOSHIBA ?????
TransistorArchive: ????SONY ?????
TransistorArchive: ???SANYO ?????
TransistorArchive: ???MATSUSHITA ?????
TransistorArchive: ???HITACHI ?????

TFK OC/OD Germanium Power Devices Series
telefunken
techinfo2

list of a wide range from vintage transistor data books
Hersteller und Quellen - Manufacturers and References

Overview and short form data of BjT Germanium power devices
Bipolare Germanium-Leistungstransistoren - Bipolar Germanium Power Transistors
Grenzwerte von Germanium-Leistungstransistoren - Germanium Power Transistor Maximum Ratings
elektronische Bauelemente - Transistoren

Delivery Source - Ordering Address
Results for Semiconductors:Vintage
Atomic Mall - Related Items

Advices to additional Delivery Sources
Germaniumtransistoren, wo zu haben? - Mikrocontroller.net

First Examples of first generation Solid State Radios/Receiver, Integrated Amps and Power Amps
http://home.arcor.de/pfaue/klangkue/verstaerker/beo/beo900.htm
TR1 - Hardware-Fachbegriffe Online Lexikon (erstes TI-Taschenradio)
Drucker, Geräte von Dual, Röhrenradios Dual erster Transistorverst.
Mein eigenes Kolter-Museum
Transistorradio
Radios Antigos no Brasil
Vintage Radios Australia
Silicon Chip Online - Vintage Radio

I've got this Sansui AU-X1 in the workshop in order to find a solution to prevent the issue with output stage oscillation, that had caused some AU-X1 to burn out the output stage.
I've been reading some threads on several fora e.g. audiogon etc. regarding this issue, and it seems like this issue is only present when no speakers/load is connected - even only a set of connected headphones should prevent this oscillation. I did not find any add-on/mod solutions though!
Then in a short "brain fart" it came to me, that if one build in a separate seudo headphone load (resistors, inductor and cap only), the problem should be solved. This would only put very little load on the output stage and would not affect the performance in any way......
What do you guys and girls think??
Thanks for any input to come 🙂

Hi
I would like to buy a Genelec speaker on Blocket se I not sure I can register from Denmark.. Can any Swedish members help me out..

Best regards
Steve

Does anyone know the exact quantity of ferrofluid a T33 tweeter uses?

I've heard everything from 100uL to 250uL. I was going to use half of a 300uL packet.

I dont trust the internet on this one judging by the dried up amount I removed, which wasn't that much compared to other tweeters.

I have for sale a ice power as 1200 as2 .The amplifier has original accessories and warranty.
I was bought on European store. Used on PS Audio Stellar M1200 - not cheap...
I asking 300€.. shipping registered on Europe included.
Is like new.

Subject amp was brought for next to nothing and it was gutted. All that was left was the chassis, the transformers, the tube sockets, and the heater wiring. I replaced the sockets and the heater wiring and I tried not-so-successfully to nickel-plate the bell ends of the transformers. From what I've been able to tell the amp was made circa 1960 and was part of a transistor-based organ (part of what was in this chassis was the power supply for the organ electronics; all of that's gone and the associated PT secondaries are blocked off and wrapped up).

Obligatory gut shot:




The schematic shows one component change (unobtainum; substituted 250 ohm 5W for 225 5W) and I've crossed off sections that were omitted. I crossed off the input/V1 stage because I changed enough to just redraw it; both are below:







I simplified how that first segment of coax is drawn; the actual layout doesn't look like that. Rather, ground "emanates" (if you will) from the end of the preamp-side ground busbar to the low leg of the volume pot and is carried via coax shields from there towards both the input jack shield contact and toward the V1 grid(s) but note that the segment of coax from the volume pot to V1 is grounded only at the pot end - this was a late addition to address some audio-range feedback that was creeping in. Both input and speaker jacks are isolated from the chassis. The big changes in the front end are the paralleling of the two V1 triodes instead of leaving one unused, the values of V1's cathode resistor and bypass cap (I had intended to use a 10uF but didn't have one on hand), and the value of the V1 plate resistor (started with 56K; wound up with 47K). I tested putting a 4.7K resistor in front of the V1 grid(s) to reduce how much the function generator input signal was getting dragged down when the volume pot was turned up but it didn't seem to help much at all so I removed it.

The power tubes are new TAD 6L6GCM STR Redbase. The two 12AU7s and the 5U4GB are vintage; they were collected from the same source and are branded "Beckman" (electronic medical equipment manufacturer). All were tested on an Eico 667.

The two ground busbars meet and turn together toward the preexisting solder blob. The ground wire from the power cord and the PT center tap are soldered together with the two busbar ends into a thick column. There was a now-unused connector near one of the 6L6es with a terminal placed ideally for the far end of the power stage ground busbar to be soldered to in order to stabilize it; I chose to leave it like that.

It amplifies.

Power - By connecting the amp to an 8-ohm resistive dummy load with a scope across it and feeding a 1000Hz sinewave into the input, before the output clips I measure/calculate 18.6W going into the load ((Vrms^2/8). That's not the ~50W I was expecting. I have read here that it is possible to have a dual-6L6 amp in that power range in Class A but I'm not savvy enough to know if that is in fact how this amp was designed or if I have something else going on that's out of whack. I can say, however, that when I adjust my variac to get the 500V B+ as indicated on the schematic, all the other indicated voltages are very close to what I measure. It may be the case that the 250-for-225 substitution of the 6L6 cathode resistors wasn't a great idea; I could parallel a 1/2-watt 2.2K there to bring it to 224.5.

My intent was to recreate the APS-5 as opposed to put something else into an APS-5 chassis (after all, the transformers are for the original APS-5) so if it is in fact an 18-19W amp then so be it.

I've been doing some reading and my understanding is that what characterizes Class A operation is that the power tube plates are carrying a current which tracks the input signal throughout its entire excursion. I suppose I could put a small sampling resistor of sufficient power rating in series with a plate and throw a scope across it (while the amp is on an isolation transformer, of course) to determine if it's running as Class A; does that seem worthwhile?

Frequency Response - my -3dB knees are at 130Hz and 25kHz (!). I would have thought I would see a lower bottom end but I don't know what's typical for this sort of amp. It is not audibly lacking for bass running ordinary music program through a three-way loudspeaker.

Phase Response - If my input signal is around 10kHz, I've got something like 30 degrees of phase shift. Is that normal?


I welcome your insights and I thank you in advance.

(this is a segment of the upcoming "Karlson Compendium"

John Karlson and Wayne Green completed the famous "K15" prototype in the summer of 1951 and it was introduced commercially at the big names Hi Fi show in the Hotel New Yorker, Fall 1952.


K15 had a long run, produced in the thousands, but as time moved forward and the playback mediums of vinyl and tape heading away from mono to two channel, plus the acoustic suspension revolution of Edgar Vilchur and Henry Kloss, K15 was too cumbersome in pairs for small rooms.

Karlson with the 1964-65 World's Fair and K15 with Electro-Voice 15TRX supplying sound for a number of exhibits including Disney.

It was late 1965 when AUDIO Magazine's Annual Directory announced Karlson's X15 speaker. It featured a custom CTS woofer, much like a K33 but with less excursion and higher sensitivity. Also, the first model used a 3 inch cone speaker which fire into a custom Karlson asymmetric ("klam") lens. Subsequent models featured a slotted pipe with a one inch format compression driver made by University Sound. Two different diameter slotted pipe waveguide have been seen so Karlson was certainly experimenting Also, one X15 for organ use had a conventional horn in its front chamber, pointing up at a angle.

X15 with nominal dimensions of 28" tall, 20" wide and about 14" deep, had roughly a bulk of only 4.3 cubic feet - just one cubic foot larger than Karlson's 12 inch ("K12") model, and only about 57 percent the bulk of K15, so a stereo pair really could fit many rooms.

At ~57 percent bulk of K15, and fixed sensitivity 15 inch speaker, X15 would have its low frequency cutoff about a half octave higher than that of K15. Nonetheless, like a good K12 setup, percussion transient are impressive and cone excursion in the passband reduced vs a 12 inch speaker.

Also, X15 incorporated a 3 panel approximation of an ellipse curve upper reflector. (That was covered as an improvement in Karlson's 2nd and final "Acoustic Transducers patent,, #3540544).

Sometime around 1980, a number of X15 size K-coupler appeared on the market. I think Karlson's widow sold rights to at least 5 companies 😀 There was Transylvania Power Company, KK-Audio, Acoustic Control, Westwood, and a little company in Chicago, all producing pretty much the same cabinet.

With hindsight I wonder if these company's even knew there had been an X15 already with large port, pretty much what they ended up building and same with Cetec -Gauss when Karlson already had a "K18"

FWIW, I'd love to find someone who would make a nice pair of the wooden klam to try with say Faital Pro's 3FE22

Hello dears
I have recently aquired tube preamplifier from one of my friends, he claims that he got it from Singapore, i saw same design on ali excpress though. Anyway, pre is very nice, in very good shape, sounds amazing, however, i noticed small shhhhh sound when i put my ears next to speakers, this shhhh were audible on my solid state preamp before also, but was twice lower,

This preamp is pushing allot of power to my power amp were i need to raise volume only on 1 ( 8 o'clock ) , i will try attaching some videos and photos for the pre and willing to get your kind openions.

Tube pre (unnamed)
Power amp (krell kst 100)
Speakers ls50
https://photos.app.goo.gl/RxKK8sPHEoCdSdrY9

Thanks

Hello all,
I've been perusing the forum for years, however this is my first post.

I bought a Naim Supernait (version 1) on eBay a few years ago and it was not functioning properly. I missed the return timeline.

The issues- right channel has pretty significant buzz/hum.
Amp sometime automatically mutes (safe mode?)
One input plays, a few have no output and one (the Tuner) input through my main house breaker once. Yeah, the main one....
I've pop'ed the hood and nothing looks obviously damaged.
I have a meter but no scope or other audio repair equipment. I'm confident in replacing a cap or resistor if this forum can help me diagnosis, otherwise it's going to have to go back Naim for the $1k+ repair.

Thanks all

Hi, I am thinking to use this LT3045 board (LT3045 Dual Channel Positive Voltage DC Power Supply Low Noise High Precision Linear Stabilizer Upgrade DAC - AliExpress) to build regulated power supply with batteries.

Target usage:

5v DAC (powered by USB type C, 3W max) by using one LT3045 board with parallel output
12v Tube preamp (should be less than 1A) by using another LT3045 board with parallel output

Before go ahead, I would like to seek some advices here. I hope you can share your valuable advice as I am pretty new to DIY hifi stuffs. 🙂

Questions:

1. Does it make sense to you at all for the target usage?
2. Which battery type is better (i.e. having lower noise)? NiMH or Li ion?
3. Can NiMH provide enough current for LT3045?
4. For 5V output, what would be the ideal DC input voltage?
5. For 12V output, what would be the ideal DC input voltage?
6. Any linear regulaor that is bette than LT3045 for my target usages?

Thanks a lot for your advice.

There are an old thread where another experience the 13M/8636 suddenly died, apparently without any cause. Here
I disassembled mine for a closer look.
Using a sharp surgery knife, I was able to carefully lift the rubber surrounds from the basket, and do the same with the spider.
The tricky part is to get the knife under the rubber/fabric without cutting.
When the rubber/fabric is lifted a bit, the rest comes off rather easily.




Here's the one side wire going from the coil to the litze thread:


And the other side, where the wire from the coil reveals to be corroded (all black and swollen):


Removing a bit of glue to expose the wire itself revealed that the wire is simply falling apart when being touched,


I decided to remove it all.
After carefully having removed the glue this is how it looks:


Turned out that the wire was more or less corroded through the spider.
Scraped the lacquer off the piece of coil wire where it seems solid and soldered a replacement wire


The wire and solder points has been soaked in glue, similar to the un-damaged side.

Have tested the driver, having the rubber surround and spider hold in place using a bunch of clamps, and it seems to work just fine.
However, I still need to find some way of removing the old glue from the spider, before glue it again.
Any ideas?

The eurovox brand amplifier, model: EV-A1000D
This amplifier does not have audio. Check with the oscilloscope. I do not have a pulse train in the gate. Apparently the transistors Q110, Q111, Q112 were manipulated. I don't know if they are the correct license plates. If anyone had information about the amplifier or which pulses to check, I would appreciate it. much Greetings.

Does anyone have a source for the usual practice of designing loudspeaker at 2/3 of the each drivers RMS (W)

thanks!

Let me know. Thanks!