Hello all. I am trying to put together a BOM for a 12AX7 Baxandall tone control board that I bought quite some time ago. I can figure out most of the components by reading the rather good information in the silk screening on the board, but I am not experienced enough to determine resistor wattage by "eye".

Here is a pic I found of a finished board. If anyone could help me determine wattage values of the resistors it would be a huge help to me.



What I see are "small, medium and large" - I could assume 1w, 3w and 5w respectively, but I don't want to assume.

In an attempt to fill the hole left by Antek, I have contacted Primrose of SumR about a GB for Toroids. While they are more expensive, in theory they should be of higher quality and more suited for HiFi. In an effort to get largest possible discount, We need to try to limit the VA rating of the toroids to two, maybe 3 different power levels. I was thinking 400 and 800 VA. At a quantity of 25, we get about a 12% discount, with qty of 50 bringing about a 25% discount. This is supposed to be per VA rating, but i think he make an exception if we can get the numbers up. He is willing to drop ship to locations, so there will be no added shpping cost over what is normal.
I think the best idea is to post your name and desired values and lets see where this goes.

Hello all
I have just received my kit and am starting assembly. I am inserting the input/output RCA connectors. Should I dremel around the hole for better contact ofr the earth connection ??
Cheers
Bruce , Oz

Free x-over parts from GNP Valkyrie Speakers. Free pick up or will ship at your expense. Located in Ventura CA.

Hello All!

I have a Skar RP2000.1D that I am repairing. It had all the output fets shorted and also 3 of the power supply fets shorted, along with some of the gate resistors. I removed all the FETS, and was curious if I can check the gate waveforms with the FETS removed, or if the driver IC for the power supply needs them in place to get its power.

Just trying to learn while I wait for parts to arrive!

Thanks,
Mitch

Included is a stock photo of the guts. I'm at work right now and don't have the amp near me.

Hello! for long time i haven't had any bass amp to gig but i have some parts at hand to build one, i had experience giging with a improvised 12W tube amp for rock/heavy blues with a dirty bass tone with no issues, but i need a bit more power in the range to 18-30W to play more versatily with more headroom with enough OD.

Short story, my plan is to build a Marshall 1959SLP clone with a pair of EL84 at the end fixed bias, at 450V B+... yes is kinda high but has anyone tried it before? btw the screens are on the range, at <300V and plates idle at 24mA, with those voltages the amp gives me 25W-ish (10%-ish distortion) and 30W full clipping.

I've heard some people prefer cathode bias over fixed for this tubes because at higher voltages don't sound very good nor the linearity, anyway i'll attach the circuit if you wanna check if i'm way out of spec or there is any hope.

Hi,

I searched.. hope I'm not duplicating (again)

Do you like your beer / lager with a head or full to the brim?

Does anyone have a schematic for a Danelectro model 78?

It looks to be all original. Has the two prong cord.
I didn’t plug it in.

Hello!
I'm trying to rewire this plate amp to SE mode. Since I have no clue about what I'm doing I thought I might get some help on this forum. So far I've reconnected the cables as pictured. The problem arises when connecting the RCA. There's a loud howl when powering on and the cone starts to move outwards. At that point, a second or so, I turn off the amp.

Some clues about where and what to look for is appreciated. I have a basic multi meter.




Edit: SE mode = Stereo mode

I picked up a half dozen of these at a local estate sale that I would love to use. There are a few things I need to know that isn't mentioned in the datasheet.

1. Can I use capacitor or choke input?

2. Voltage drop

3. If capacitor input is ok, then max capacitance

If anyone has used these please let me know

I have a 120mm tunnel heatsink that I'd like to give away. It's 11.5" long and supports 120mm fans. Pickup in the San Jose, CA area or you pay shipping.

Many important things happened in 1977 in the audio world.The least important one was the fact that i was born that year, obviously...

One of the most important though was that E.F Taylor came with a very interesting phono preamp who's beneffits can be scrutinized in this document found here :

https://www.keith-snook.info/wireless-world-magazine/Wireless-World-1977/Distortion%20in%20low-noise%20amplifiers.pdf


I am trully thankful to KCP for pointing me towards this design a few months ago. As i'm lazy i ignored the original schematic and i told myself that maybe nowaday's op-amps can do the job without the frontend transistors, but i wanted to use one of my preffered and easy to use riaa network which leads to some problems as the headroom srinked heavily with available modern op-amps, but i wanted a 10x headphones amplifier next to that phono preamp and that was already built for the max headroom of Bayerdynamic DT880-250 ohms version, so i couldn't get Taylor's phono preamp gain on board too due to my needed overall gain of phono preamp + headphones amp... I built two different versions, one supplied with +-21.5v based on M5220, and one supplied with +-16v based on OPA2228. Some may wanna try different op-amps.

I could tell a lot about all the things i tried with this phono preamp but some may be unimportant so i won't dive too much into it. One of the most limiting factor was that my Technics Class AA based headphones amp is supplied at +-11v and with a gain of 10x the phono preamp headroom is really problematic on dusty records, so i tried some soft clipping methods, but in the end i chose to simply clean the records and let it go...Probably my next approach will be to build a proper compressor.

The only reason why this type of phono preamp never got famous is that you need to rewire the tonearm shielding wire in usual turtables (mine was Dual 701) and attach the preamp right at the end of the tonearm's wires and shield the whole thing which i did.The supply wiring are shielded, including the ground and the shield wire itself...i know...it's crazy, but the final result is fenomenal and if you didn't try that yet it's just about time!

I had two questions that I was wondering about. First is: has anyone tried swapping coupling caps to change the sound of the amp? Its been my experince so far that driver tubes didnt make a huge change in the sound and I was wondering if swapping in more expensive coupling caps would have much of an effect or not? Second question is does anyone know how big the holes on the pcb are for c9 and c11? Im wanting to use miflex copper caps but the leads and a twisted pair of wire and are pretty large. Thanks

Hi folks!
Since I bought Altec Voice of Theatre A5 speakers, I’m trying to materealize my idea and change my 300b amp to something even more low power.
Would love to try 205d. Any ideas what circuit and OPT I should try / use?
What about recreating Yamamoto 205d amplifier?
Also, any impresions on how 205d sound vs 300b, and in general low powered amps sound is more than welcome

I recently bought an LJM capacitance multiplier (power supply filter).

The 6800 uF 63V Nichicon KG have very messy printing/sleeves.

The United Chemi Con LXZ are a value that I can not find in the datasheet. 2700 uF 63V does not seem to exist.

Are these yet more fakes?

NAGRA Jean Claude Schlup Gİft 1 - Plasma Tweeter Schematic, Pictures

Hello there , I have an suprise to you. I am communicating with nagra chief designer and he sent me two gifts. First his lab plasma tweeter pictures and schematic , other is for driving tweeter , 300b active part and driver. Second will be at tube amp section.

If you want larger scans and video , visit libgen.rs - notice for later libgen visitors , last to digit changes , look from wiki , download links 1-2 should work. Search for NAGRA.

Lets tall about how to build plasma tweeter ?

I am looking for advice how to eventually improve Yamaha AX590, AX592, AX596, AX870 and AX890 amplifiers by modding them.

All of these amplifiers have basically the same power amp structure. And having read Douglas Self’s book on audio power amplifier design, I suspect some potential benefits in modding these amplifiers. I will try to enumerate my modding candidates along the specific circuit of the AX596:

- Input differential pair: Include Q103/Q105 collectors GM degeneration resistors for improved linearity ot the input pair (along with a suitable Ic)?
- Input differential pair current source: Split R123 and add a midpoint capacitor to V+ in order to improve PSSR?
- Input differential pair current mirror: Approximately match both Q107 and Q109 and reduce the values of R113 and R115 to max. 47 Ohm ... 100 Ohm?
- Dominant pole compensation: Is performed by C105/R117/R199 at base of Q113? A Cdom between - Base of Q113 and Collector of Q115 might be a better option, along implementing an output-inclusive compensation (Self, 6th edition, Page 339)?
- VAS: Quite low Ic for Q113? Increase it to fit the best possible value? Or exchange VAS type altogether?
- VAS: Cancel/omit the (Self: cruel – sic!) open loop gain reduction which is performed by Q115 collector’s loading down to ground by R201?
- Bias voltage generator: Insert a trimmer in Q117 R network (for all AX59x, the AX870 has one)?
- Output stage drivers: Fit a parallel bypassing capacitor along FR101 in order to improve switchoff behavior of Q119A and Q119C?
- Output stage power devices: Decrease Q121A, Q121C, Q123A and Q123C emmiter resistors R111 and R135 values to 0.1Ohm instread of 0.22Ohm, in order to improve linearity of gain in the crossover region?

I use several of these AX59n, AX870 and AX890 amps for multichannel projects. And it seems, that these inexpensive mods could more or less easily be done on the printboard. But is it really worth to switch on the soldering iron in order to perform some of them? And if so, which ones? And maybe I overlook some candidate mods?

Thanks for any advice. And also thanks for an eventual link pointing to an AX890 service manual – it seems nowhere to find in the net.

YamahaAX.jpg

Hi,

I bought a used 1970s era console stereo made by fleet wood with a garand 3000 turntable in it. It sounds pretty good (to me and for my purposes: a stereo my wife will let me have in our living room), but the left/right balance seems to be drifting, and it gets more dramatic as it warms up; but even when it’s cold the balance needs to be adjusted to be centered relative to the center position on the adjustment dial.

I’m not sure what this could be. I wonder if it’s a transistor dying or if it’s a capacitor? Anyone have any thoughts or suggestions on how I could figure it out?

Hello all,
Is anyone aware of a good source of information on reading THD frequency sweep graphs so as to identify the prevalent sources of distortion in a particular solid state amplifier?



I am working on version 2.1 of a solid state amplifier board and have made distortion sweep graphs (THD, 2nd harmonic, 3rd harmonic) at various operating conditions (1W, half power, 50W full power ; 8ohm, 4 ohm load) and now am working to unpack the graph lines to discern which amplifier distortion mechanisms are dominant and need attention most.



I have worked (several times) through my copy of Douglas Self's 6th edition work on power amplifiers, but would find it helpful to review an article or chapter that lays out how to ID the various distortion sources from test data in one consolidated source. That type of information is splattered across the whole length of Self's book and I have tried to sift it out slowly.


Any tips would be appreciated.
Mike Miller

Hi everyone🙂 Straight to the question, although it has whizzer, lighter cone, low mms and mmd; there is no information about that on the manufacturer website, not even full t/s parameter and frequency graph. Is it a full range driver?
Though they(Sweton, an indian speaker manufacturer) claim to be market leader in india and overseas, i have no hesitation in saying that this claim is absolutely false.
They will even fail to compete with reputable foreign speaker brands. No chance! But currently i have no other option 🙁

Hi there! I am new here and I will try to be precise with my wording. The plan is to build a subwoofer for my home theater. It'll be the Mivox XAW 320HC

It seems that it has the possibility to add several weights to it which changes the response quite a bit. What would your choice be? I am not sure what tuning frequency would be good but I would have no problem building a 200liter enclosure!

Thank you!

My brother gave me an old crown amp. Its been sitting in a closet for many years. This monster is too heavy to lug around to gigs, so I replaced the input jacks with rca jacks, and hooked it up to my acoustat 2+ 2's. It would sound great if it wasn't about 10 dB louder from about 2 kHz on up.
Considering my Acoustats are a real brutal load in this region, I am perplexed why.
I did not replace any caps as they all looked good. And replacing the big cans would be more expensive than I want to do at this time.
Would not replacing the cans cause this.
Also, the volume pots almost all the way up does not give the volume I'd expect from my cd player.
When using my pre amp (audible illusions) I can drive it better. So I assume that p a amps have a higher input sensitivity?
Thanks,
Paul

Hi all,

Last weekend we did some measurements on a big subwoofer I designed for a friend of mine who will be using it in the LBB Maastricht (The Netherlands), an alternative place for artists, creators and skaters. I am eager to learn what the crowd on this forum has to say about it. The good AND the bad! Maybe we can improve on it with things we hadn't thought of before.

When setting out the design there was a definite constraint: it had to fit in the elevator and fit through most doors. Everything else was no issue. Well, maybe except for price of components of course. Coverage: as deep as reasonably possible without sacrificing too much sensitivity, it is intended for PA use after all.

So... I took the proven 18SW115-4 as a starting point and tried different concepts, mostly FLH and TH. I ended up with a big box that would fit in the elevator and an extender that can be added for extra extension of the usable frequency range, sacrificing a little maximum SPL.

From the looks of it, and from the kind of music that was often going to be played on the system, I suggested to add kickbins to the PA. For that we built the Cubo kick 15, loaded with the 15NLW9300-8.

In the attachments I have included the Hornresp simulations of both subwoofer designs, so with and without extender. In the following post I will include the measurements (compared to the Cubo kick for "reference").

Hi all, I have for sale a brand new BMS 18N862 (8 Ohm) 18" subwoofer driver. Purchased for a project that never got off the ground. It is brand new and never used, still in the original box. Awesome cross between Pro audio and HiFi subwoofer.

Looking for £395.00 inc. UK shipping. Will ship worldwide at cost.

Thanks for looking!

Hello everyone
My name is Walter and I'm a newbie here.
I'm planning to buy a tube amps for guitar and I don't know which is better. Marshall Origin5C or Bugera V5 Infinium.
My budget is enough to buy one of them so I really need some advice
Thank you

Hi there,

El Menco , Zenith , Silvertone
anyone know that tubes? Are they good for audio use?(double-triodes)
Thanks,

Hello All,
I am in the process of repairing/ restoring a Citation 22. The relay was clicking on and off repeatedly at random times while on, and the amp froze in protection mode. I went into a thread about the protection problem and wound up replacing the C11 33uf cap on the main board. I found this solution on an old AudioKarma thread. This got it out of protection mode, but the relay was still clicking on and off while the amp was on. I decided I would go and recap both the relay board, and the protection board. I also cleaned the contacts on the relay and the power switch. I have to say, I think the problem the whole time was just the power switch and the relay contacts oxidizing. I was very happy when I powered it on and it quietly and quickly clicked on and timed out of protect mode quickly. There was an immediate issue though, in that the status lights in the front of the amp that indicate "High Current" and "High Voltage" (these also switch the amp B/W 4ohm and 8ohm mode) are now both totally dark. The High current one used to come on right away, even before it timed out of protect. Is anyone familiar with these amps and experienced the same problem? I checked every solder joint I touched 5 times. Nothing is loose or cracked. I can't bring myself to reassemble it as it is, even though it seems to be working correctly. Anything would help.

Also, this is the first time I have posted in one of these so please go easy on me and I hope I didn't break any rules or anything. Thank you!

Hi, I would like to learn more about Class D (PWM/PDM) amps, mainly for driving headphone loads (about say less than 5W into 32 ohms in the worst case scenario). I understand only the basics of how it works. I would like to know about the difficulties and implementation of good quality Audio Class D amps (like Hypex, Icepower etc), and posting here seeking for guides. I have fairly decent idea about BJT/MOS devices, especially linear amplification, and a little bit about feedback and regulated power supplies if that helps.

I also came across a category called Fully digital Amplifiers, and I would like to learn about it as well. I think I can code my sbc to do the necessary PWM/oversampling part so I could even skip the ic that does this conversion, and only focus on the Digital to analog conversion part.

Thanks.

Hello

Is there anybody who could provide me a service manual for the pioneer C73 pre-amplifier.

I have a problem with mine.

Please use: student_fhc@web.de

Thank you very much

Kind regards
Stefan

Very interested by his design of a THD meter I tried to contact him via email but to my disappointment he did not respond.
So I decided to make a copy of his published PCB layout with fritzing and, approaching the finished layout, I was wondering
if somebody else on this forum did not already do this and gained some experience with that design.
Hope someone will respond.

Hello,

I've been trying very hard to understand how to build the best enclosure for any specific speakers. My last project was a small bluetooth DIY speaker using two Visaton FR10 and a TDA7492P Sanwoo board which didn't please me that much.
I currently have some old car speakers laying around and i'm trying to use them to build another stereo speaker system. The speakers are two Hertz EV 130.5 4 ohm, two tweeters Hertz ET 26.5 4 ohm and two cross over Hertz CH200. Essentially they came as a kit. I also have an Yamaha rx396 amplifier with 50w at 8 ohm that i will use.

I've used WinISD to calculate the volume for the enclosure but that's where pretty much where i got stuck. It gave me a 31.9 litter cabinet with a 4.7 cm vent diameter and a 3.19 vent length.

Now, the vision in my mind is that i want them to be tower like enclosures. I don't know how to determine the best design for this(widh, height, lenght), where to place the vent port (the middle, down or how far from the speaker).

If anyone can help me with specific details due to the fact that i am very new at this and trying to understand logical way how to do it. Or any links to youtube or this forum tutorials (i've tried search but i don't know key words what to look for) i would appreciate it very much.

When I got this amp on it had all of the output filter caps blown in it .

I replaced them and get pulsing DC voltage measured across the output terminals

There are 2 driver ic’s for the output IR2010S

On 1 of the driver ic’s I get pulsing voltages also on pin 8 which HO pin

I tested the components in that area and all test fine wondering could the driver ic be bad or is it more likely something else is causing the pulsing DC on the HO pin ?

Hello there , today this is my second post , nagra chief designer gift 300b active part and its driver schematic.

Lets talk about how to build it ?

I'd prefer to find new homes for these spikes, rather than throwing them in the trash. Just pay shipping + pp fee of $9, and these will be on their way to you.

1. (Claimed) 8x spikes in gold, with discs. 3 bonus spikes in matte grey.
2. (Claimed) 8x spikes in black, with matching discs (hard plastic)
3. 8x spikes made by Zu. These are M8 threaded and tall.
4. (Claimed) 4x Vibrapods No 2. Retail $24.

Drop me a pm if interested and I'll share pp email. Thanks!

Do anyone know what the loadline would be like when there is cathode degeneration / local negative feedback? I guess that effectively means under AC the grid curves will become more crowded towards the curve which the tube is at that particular Vg (which is dynamic and following the AC signal), that means the headroom of a particular bias set towards Vg=0 remains the same compare for the one without cathode degeneration. And for DC, the curve will just like the one without cathode degeneration. Is that correct?

I modify my Northern Electric LR mono amplifier.


What I get now:
4 * EL34 in PP and parrallel config.

75 watts of power in 4 ohms at 450 v
I could go more power (90w) with Diode, but go back with 2 * 5U4 at 75w/450v.

To get that I use an 1650R Hammond OT


To develop this amp, I use the OT from another amplifier. So need to return it back.


It play verry good in my housewrecker box as a sub for my A7 with 2 * 15" in Isobaric config at 4 ohms.


So I need to buy an new OT.
Should I go with an 1650t. As it is 1900ohms agains t 5000ohms for my 1650r....
I'm not so sure...?

Even if will get lot more ma.
Lots more possibility to modify with an 1650T
(But power transfo is limited in current... May be not as crucial as it appear.)



Any infos I need to know from your experiment before my final choice?



Mario

HIFI mono LM3886 power amplifier board / can be connected in parallel | eBay
Anybody tried this one?
I have built a couple of the LM3886 chip with the XY pcb. Use a starground bolted to the chassie to get rid of some hummmmm. There are still a little bit hum, so I think I will build me another amp, with another type of PCB. Perhaps there will be no hum on this PCB?

At this model I have perform service work and maintenance several times. But the currently device has an unusual error:
The disc try to start but does not really running. For reading in the TOC the correct speed is not reached. When I turn on the compact disc by hand while the time of start trial immediately after FOK the running process goes on and the disc read in the TOC. By pressing the button "PLAY" I must also do turning the disc by hand because otherwise the disc in this phase even only tried to run.
Until now I haven't observe this. Actually only the Spindle-Motor or the driver IC from Toshiba must be defectice resp. faulty. Are there also additional causes ?
Thank you very much for your helping.

Vovk Z, in recent thread argued about interest of keeping some caps on drawer.
I agreed with him as local resseller disapear and online orders require a minimum amount.

which aluminium caps will you recommend or kit (if exist) for inputs of audio circuits ?

Hi all this is a long shot but as anybody got any servics information for this keyboard. cheers

jim

Opamps for everyone.

http://www-s.ti.com/sc/psheets/slod006a/slod006a.pdf

And a "Handbook of operational amplifier applications"

http://www-s.ti.com/sc/psheets/sboa092a/sboa092a.pdf

These are good material for those new into opamps. Everything (nearly) is mentioned.

Try out a "bubba oscillator" With some gain control this oscillator shows of a distortion level of ~0.03% and has a stable frequency to, but it is only a basic circuit shown.

Sonny

this circuit has vr10k adj volt 1/2vcc it use vcc55v-100vdc

vdo 100w OTL W????????56-100vdc by fodland - YouTube

SO I Impulsively Bought - On sale - 2 Of the Satori mr 13-4 ( mid-range ) drivers Did A quick search -After the fact and found while there seems to be Positive comments for the driver - Im am not seeing the implementation in any designs - At least publicly - Thinking about a three way - Any thoughts ? Pairings ?
undecided on both base driver and tweeter The sensitivity on the Mr 13 is 91 db - with this in mind the EATON 11 in (11-212 ) @ 91 DB 1W /1m seem to fit,though a all Satori approach has some appeal - the Wo24 p ? looks interesting , these will be paired with Quicksilver Mini mites, if that makes a difference. Listening levels will be modest . What do you think ?Thanks in advance

Ive had a hold of a philips cd304 for some years now with the intention of having a go at repairing the unit.
Im a keen diyer and after breathing new life into an old nad 3020 just by replacing the caps i felt that id give the cd304 the same treatment .
So far ive managed to replace most of the caps with like for like and the cd player is now working again !
The only areas i havent tackled to replace the caps are the two main boards that sit back to back.
Now although the cd player works and sounds fine ,it will only last for about 30 mins before failing to read the disc.Even if i change a disc or start again it wont read ,up until i switch it off and leave it for awhile.
So would changing the caps on the main boards be the likely culprit ..mostly philips caps (One of which i cant figure out it has 150u 6v3 )
I feel im in touching distance of completing this fix .
I have also gone over the solder joints .
Any help would be greatly received

Hi everyone 🙂 I've attached the output buffer part of p81 knowing that the project-81 is a intellectual property of rod elliott; bcoz i had no other option. Anyway, my question is about the use of dc blocking cap after VR1(in series with non-inverting input). As you can see tl072 is shown here as output buffer but i want to use bipolar input op-amp like 5532. So my concern is input bias current of 5532, quite high in comparison with tl072. Can i use 1uf film after VR1? I mean here the procedure maybe as same as calculating high pass filters for power amplifiers, preamplifiers?
I'm not sure because as far as i know filters are quite sensitive.

On the other hand since 12db/octave Xovers always invert the phase of one signal, which one would you like to invert? High pass or low pass section??

Regards
Nirupam

Hello Diy Members.

I have a pair of Philco 47 globe tubes and want to built a Se amp with these tubes .
Now I am looking for the triode data .

Thanks, Martin.😀

Just wondering whether sources can be connected to the slave amp or can you only connect a source to the master amp?

Thanks.

A lucky find at a local thrift landed my kid a reasonably current PC for his on line school lessons. I took the laptop guts he was using (Celeron, 8GB, W10 128GB SSD) out to the garage, where I have it connected to a large monitor via HDMI.

I was planning on using a BT connection to a compatible amp board, for some background music when I work out there. This proved to be impossible as it would stutter and stop (reporting file corruption) before even 1 FLAC file song plays through from my NAS. Removing the bluetooth dongle, it plays fine (with only occasional minor hicup) listening with headphones on the headphone output.

The kicker is that any radio stream, and youtube video doesnt do this. And, in the very same spot, a much less Intel Atom powered (1GB mem, SSD) mini-lappy running Linux streamed from the NAS just fine, using the same BT dongle, but was so underpowered it wont render video - at all - from YT.

I replaced the BT amp with one having analog input...so I can listen to something in my NAS hosted collection. Amusingly, my rPi based bedroom system plays from the NAS flawlessly, while the mighty Celeron / W10 / 8GB has all the trouble.

How would I go about diagnosing this? The Celeron laptop MB is mounted bare on a piece of wood. It seems to run anything locally just fine - oscilloscope programs, web browsers, players. Thanks!

Group Hello
I have a good friend in Philadelphia PA area that needs to have his Emu Drumulator 7000 checked out. From his description of the problem most likely needs a PS rebuild. I would do it but I moved and in the process of setting up my gear.
If anybody knows a Tech in the Philly area that is skilled and familiar with rebuilding PS please reply to post or send me a PM. Unit is from 1983 not beat up one owner.
TIA

I need to build a power supply for a Musical Fidelity M3 Nu Vista Integrated Amplifier.

Is it feasible to undertake this as a newbie?
What would the potential cost be for the entire project.
Where does one start?

The backstory
I won the M3 in a Thiel Audio liquidation auction. It didn’t come with the power supply so I’m investigating building my own.

I'd like to minimize the size of my dipole bass arrays by using an H-frame but do not want to sacrifice clarity for increased distortion (ie a noticeable increase). I'd love to mess with designs, but have no idea how to calculate the resonance for the particular woofers (I'm using 2 towers of 4 RSS390HFs per side in a line array). Crossover point for these (crossing to a rather large ESL) would be in the 150-350hz range with 48dB slopes.

Im crossing these over to a diy ESL (~25" diaphragm + frame) and may experiment by using it as an extended modular baffle of sorts for the woofers.

The amp powers up fine but as soon as signal is applied it clicks off

Hi everyone I was hoping someone could let me know if they have experience with this kind of thing.

I own a Chiro Kinergetics C-500 5 Channel Amplifier. Sounds great except...

Here’s the problem. I have been getting a buzzing in the transformer over the past couple of years. The volume of the buzz raises and lowers over a couple of minutes. It doesn’t always do it either. Sometimes it will go a week without a problem and them sometimes it will happen for 2 months straight. I talked to a Plitron Engineer that doesn’t think it’s a transformer problem. He mentioned it would probably be constant in volume and duration if it was. He pointed to the power supply and maybe the caps especially. I opened it up and saw 2 large Philips 20000uF power filter caps after the transformer on the output stages and then saw 4 1000uF Nichicon caps before the transformer near the switch relay. I wonder if it could be one of those? I also wondered why there is another transformer on the switch. It unfortunately is a little noisy also, but nowhere near as bad as the main toroid. Man, should I just toss this thing?

I know that AC noise and dirty power can cause this kind of buzz but I have moved 3 times since this started and it is always present. I have tried switching outlets and even a Monster Power conditioner and it didn’t seem to help.

Also, the sound still seems fine on the outputs (except for a faint buzz in my center channel) and doesn't get worse or better as the buzz increases or decreases. This leads me to believe the problem is before the output stages. Would this make sense?

Any advice on what this could be or even schematics would certainly be appreciated. Thanks for your time

I want to be able to use tubes that are reasonably off balance in sections or reasonably unmatched tube to tube. But I'm hesitant to add a balance control where I lose gain or cause roll off problems or cross talk or impedace issues, etc. So what I was thinking was to design the amp with 2 VU meters at the output, and a switch on the back that will send a mono 2v test tone Y'd into both inputs. The little oscillator would be built in. Then have a series trimmer pot on each channel input (somewhere).

So to "calibrate" the amp for the mismatched tubes one would turn on the oscillator and attenuate the trimmer on the more powerful channel to match the weaker channel with the VU meters. This way end-to-end the amp would balance out where it counts, the output. When I change a tube I re-calibrate it. In headphone listening I've become very sensitive/annoyed to the channels not balanced, it even happened on a solid state head amp I bought years ago, that device got quickly relegated to the junk box, it had no balance control.

Is this a balancing technique seen before in the history of amplifiers? Could channels be trim balanced with series attenuation like this, or must I investigate other means?

Hello all,

Am new to the forums and have a limited knowledge of electronics so have a question that someone may be able to help with...

I have a circa 1990 Adcom GFA-555 power amp that was purchased in the USA, so runs on 120 volts. I live in Australia which has 240 volts. I am running this amp from an external step down transformer, but am interested in seeing if I can convert it to run on 240 volts and do away with the external transformer. I was hoping there may be a way to re wire the taps from the power supply torroid that would not involve too much re-working of the amp. The wires from the primary of the torroid are as follows:

Blue ------- 120 vac \
Joined - connected to power cable
Black--------120 vac/


Yellow---------------\
Joined
White---------------/


Brown------120 vac - through power switch and fuse

Orange - not used
Red - not used

Would appreciate if anyone could offer some advice / help.

Thanks guys,

Chris

Has anyone tried complete digital solution like that?

Just wondering if that actually possible at low costs:

if im correct nanodigi ,motu 8a or OpenDRC-DA8 could do all dsp routing ,crossover and equalization

then 3 cheap digital amplifiers such alientek d8 ,fx audio 802, smsl ad18 or even newest fx audio D2160 used for tri amping

digital input -> nanodigi -> (3x digital output) -> 3 x FDA for active 3 way

or something not fully digital but with 8 dacs + class d (sure amps)

digital input -> motu 8a -> 3 x (stereo class d amps)
digital input -> OpenDRC-DA8 -> 3 x (stereo class d amps)

Can anyone advise what would be the best way to control tracked volume on that configuration for all 3 amps?


Thanks

Been a while since I did a tube project. Sit down, relax, and enjoy. 🙂
Blinkenlites - Album on Imgur

Schematic: https://www.seventransistorlabs.com/Images/Tube_Shift_Register.pdf

Tim

Does anybody know the purpose IC602 op amp that is shown in the attached picture? The channel output is fed back from the right via R614 to the input diff amp, but also via R688 to the input of this op amp. The op amp output is driving the input of the diff amp.

??

I was planning to build standard PSU with chokes and RC filters but changing the voltage is a pain. Does anyone can recommend a quality plate voltage power supply ready made or a kit for SE power amp with at least 300-320V and 60-70mA or more, preferably in Europe? Soft start, good PSRR, stabilized, low output impedance etc... I was looking on eBay but found only with low current for preamps.

From my posted at Electronics and Tube forum

http://www.diyaudio.com/forums/showthread.php?s=&threadid=76973&highlight=

and

http://www.diyaudio.com/forums/showthread.php?s=&threadid=72262&highlight=

Now I succesfull for fixed my Milbert Car Tube Amplifier by changing PQ35/35 to EI40 choke & step-up ferrite core, I wondered about quality of new core.

I learning its operation and redesigning its PCB (some concept from my master : MR.DAVID LUMANAUW)

I decide for build new Tube CAR Amplifier with 20WATTS Single Ended Class-A : 211 TUBE.

If anybody interested please notice and look this post !!! I shall d o it !!!

Regard
analog guy

I just finished a UPC1342V + NJW0302G/NJW0281G stereo class AB power amplifier board from ebay. It's all in one board (power supply, speaker protection & amp). It was cheap so I decided to build it for my surround sound speakers. It works but FFT measurement (yellow graph) looks odd.

Is anyone familiar with the distortions shown between harmonics and what's causing it? My other amp from ebay (LJM L20SE kit, class AB) shown in red doesn't have it so I'm wondering. Thanks in advance.

Hi i need a replacement for s46 transistor and s31 transistor

Thanks in advance

Let’s start with the sensitivity or could it be efficiency then bandwidth, what’s normal and what’s the top end units have? Impedance, why 4 ohm or 8 ohm, where is the performance and the reasons for the difference? Where might Ifind a thread explaining all this stuff? Thanks

During several months now I modified more or less everything in my audio equipment:

• Quad 303: refurbished and slightly modified
• Tannoy Definition D500: modified crossover and internal wiring
• Audio Server: ripped most discs I own to a tiny Mini-PC running Daphile
• Cables: made analog interconnects (pure silver), USB A-B, and speaker cables (easily dumped my Kimber 8PR for them)

The only item that did not receive any upgrade is my Rotel RC-1570 preamp.

Every single step added a bit to the overall sound improvement. But still ... Have a look at the pic I added, the layout of my living room, which is ... a little bit special. Having mostly glass to the left, and an open space to the right, from listening position my Tannoys show a nice soundstage, but always a bit non-symmetric, uneven. At the moment, the room has no special elements of acoustic treatment.

I experimented one weekend turning the whole situation by 90 degrees to the left, thus blocking the windows and door by audio equipment. It helped a bit, but did not work out from a practical point of view as a living room. So back to what you see on the drawing.

Two weeks ago I learned that BruteFIR filters can be imported to the Daphile server, and that these can be generated by analyzing the acoustic situation using REW. So all I needed was an external audio interface (Steinberg UR12, 69 Euros), a measurement microphone (Behringer ECM8000, 32 Euros), and a 5 meters microphone cable (less than 10 Euros).

My laptop runs under Linux Mint, this is why I chose the Steinberg - it's reported to work well under Linux - and so it does (more or less).

First measuring session was a bit late in the evening - I was tired, but couldn't resist to get started. So my first attempt was to measure both speakers in one run. This certainly is nonsense, but I was tired ... The generated filter had some audible effect, so at least I knew then that my first steps using REW led in the right direction.

Next day I went for both speakers separately. Same steps, adjusting gains and levels, chose sweeps from 20 Hz to 10 kHz, generated a pair of filters and exported them as .wav files for Daphile. Now the outcome was very different: all instruments got a lot more 'space' around them, were much more clearly defined. The before non-symmetrical soundstage was leveled now, and the sweet spot of listening position had been widened. But still: something's wrong.

By listening to some of my favourite test tracks, I thought most parts sounded much better than before, others left a slightly artificial impression. Just a few examples of what did not work out so well: In Rebecca Pidgeon's 'Spanish Harlem' many sibilants of her vocals appeared much harsher than before, really unpleasant. Same was true for some other female voices like Patricia Barber or Diana Krall. Male voices were not affected so much. Violins, especially in forte parts, appeared really harsh. Hi-hats or cymbals are overemphasized in a way it's sometimes really unpleasant, even at very moderate volumes, while the rest of a drum set could benefit from the filters. All kind of wooden percussion benefited, while metallic percussion often is overemphasized.

So what to do next? I'm a total newbie to REW, so I'll be really grateful for any advice by experienced users.

The smoothed SPL curves clearly show that the right hand channel to the open space in red has better linearity than the left hand channel near the wall and windows.

I exported the generated filters as .txt to discuss here.

Questions arising (incomplete list, though):

• Should I limit the filters to less than 10 kHz, so treble remains untouched?
• Should I expand filters to 20 kHz?
• Should I modify generated filters manually?
• How do I read the filter .xml export correctly (What are the 'level' and 'Q' readings about)?
• If it makes sense, can I edit the .xml manually and then generate filters from the modified files (I'm used to working with XML data, btw)?

Any ideas?

Was digging through my spare parts bin today and came across an old Peter Daniel kit I never got around to. It contains four LM3875TF chips. Four resistors that measure 750 Ohms. Eight MK132V resistors labelled at 22K. Is there any demand left for these?

Regards,
Dan

Hello all.

This will be my sixth build, but my first using an AMT (ribbon)? I'm hoping things work out. I'll check out the Planars & Exotics forum for more help.

This driver will be used in a 4-way. There will be two Accuton C51 midranges, two Acoustic Elegance TD8M's, two AE PB15H+'s, plus two 18" passive radiators. Massive D'Appolito?

Since the AE's are still months away, I have time to play with the Mundorfs and Accutons.

The test baffle is from wood left over, please don't critique?

Some preliminary test right out of the box. Near field, 1cm. Low volume. Two 4.7uF safety caps (since these might be close to the final crossover values).

I've never done impulse response/burst decay etc. measurements, so I hope I've done them correctly. If there are any other tests, or changes to tests, please recommend them.

Bought in a Marshall guitar 100 watt amplifier.
Got it cheap as fun is very noisy due to knackered bearings.
Managed to find another fan on ebay.
Opened up amp to get old fan out.
It was then I noticed while there is an in vent for the fan there is no out vent in the casing !
On my own design amps there is always in and out vent to get a good air flow through the amp.

Hi all -- I remember this being mentioned somewhere but now I can't seem to find it. As I am finishing my SE build, should I be sanding my transformers at the contact points with the chassis to create a safety ground?


The chassis is anodized aluminum so I plan and sanding a spot and using a star washer for a chassis ground, but can't remember if I need to do anything special with the transformers.



Thanks!

Two amp boards based on the P3A amp ,other layout but 100% same schematic ,complete with all the parts and with 100% original ONSe MJL4281/4302 combo .I made an amp with the same boards and it's working very well .
50 Euro +shipping

Hi. Way down here in NZ freight is a huge issue... usually about twice the price of the product, especially from US. I'm finding it hard to find 300VA 2x22v transformers to suit the Audio Sector LM3875 Kit.
I'm a noob and want advice if a slightly different transformer is ok or what would have to change to suit them.

found these locally in NZ
https://nz.element14.com/vigortronix/vtx-146-300-224/300va-toroidal-transformer-2x24v/dp/2817701

18V [url]https://nz.element14.com/vigortronix/vtx-146-300-218/300va-toroidal-transformer-2x18v/dp/2817700?st=toroidal%20transformer.[/URL]

I want to make sure I can find and afford ALL the parts before ordering anything.

Also could you explain what should I expect the difference between the "classic" version and the "Premium" version to be?

Hi All,
Since we moved back to the Netherlands I am running my Simple SE through a step down transformer but now I would like to convert the amp to 220v.
My current setup is with an 110V Edcor XPWR035 and two CXSE25-8-5k painted in black.

I am looking at the Edcor XPWR059 (provided I can get it here at reasonable cost) and the Hammond 374BX

Which one should I choose? Am I missing a good alternative?

Thanks
Jock

Hello,

I’m looking for advice on “passive preamp” potentiometer value, in order to avoid damage and avoid filtering audible frequencies.

I’m using an Arcam irDAC, which outputs 2.2V, probably around 47 ohms (I could only find this figure for the second version).

I have matched Vishay IRFP240 + IRFP9240 MOSFETs kitted up for F5 Turbo V3 and V2 builds, plus some pairs and singles are for sale. I have included BJTs for some of the kits.
All parts from Digikey.
$6/kit shipping to USA, inquire for multiple kits or outside USA shipping.
Payment by PayPal.

Kit #1 $80
F5 Turbo V3 Kit (for 2 monoblocs)
Qty. 2 Matched Quad - IRFP 240 N Channel MOSFET
Each Quad matched within 10mV Vgs @ 170mA
Qty. 2 Matched Quad - IRFP 9240 P Channel MOSFET
Each Quad matched within 5mV Vgs @ 170mA
Qty. 2 - 2SC4793 BJT
Qty. 2 - 2SA1837 BJT

Kit #2 $77
F5 Turbo V3 Kit (for 2 monoblocs)
Qty. 2 Matched Quad - IRFP 240 N Channel MOSFET
Each Quad matched within 25mV Vgs @ 170mA
Qty. 2 Matched Quad - IRFP 9240 P Channel MOSFET
Each Quad matched within 5mV Vgs @ 170mA
Qty. 2 - 2SC4793 BJT
Qty. 2 - 2SA1837 BJT

Kit #3 $77
F5 Turbo V3 Kit (for 2 monoblocs)
Qty. 2 Matched Quad - IRFP 240 N Channel MOSFET
Each Quad matched within 25mV Vgs @ 170mA
Qty. 2 Matched Quad - IRFP 9240 P Channel MOSFET
Each Quad matched within 5mV Vgs @ 170mA
Qty. 2 - 2SC4793 BJT
Qty. 2 - 2SA1837 BJT

Kit #4 $50
F5 Turbo V2 Kit
Qty. 2 Matched Pair - IRFP 240 N Channel MOSFET
Each Pair matched within 1mV Vgs @ 170mA
Qty. 2 Matched Pair - IRFP 9240 P Channel MOSFET
Each Pair matched within 2mV Vgs @ 170mA

Kit #5 $25
Matched Pairs IRFP240 + IRFP9240
Qty. 1 Matched Pair - IRFP 240 N Channel MOSFET
Matched within 10mV Vgs @ 170mA
Qty. 1 Matched Pair - IRFP 9240 P Channel MOSFET
Matched within 2mV Vgs @ 170mA

Singles
Qty. 4 - IRFP 240 N Channel MOSFET $2 each
Qty. 4 - IRFP 9240 P Channel MOSFET $3 each

I received a lot of electret cells. I look for mike preamplifier design with phantom power and balanced outputs.

any links ?

thanks.

Would anyone happen to have a copy of the manual for the ATC EC23 active crossover?

I will try to contact ATC to see if they might have something, but these are pretty old - early 90s I believe.

Thanks!

Hello,

I have for sale one SOT23-6L socket.
This fits perfectly the 2sk2145 and 2sk209 smd capsule and gives you the possibility to match those tiny smd jfets that some circuits arround here are using for some time now.

Sold

So I'm building a sound quality car audio amp to compete.
I've build several First Watt amps( F1-F5) and was wondering what would be the easiest 8 channel amp for car audio? Given the fact that I will start with 12 volts and have to come up with a neat cooling scheme. I'm a kit builder not a Pro.

2 x Lundahl LL1693 480mA Output Transformers.
$500 + shipping and PP.

I have a Forte Audio Model 1 Amp. I noticed that the left side was hot after 30 mins but the right side was cool. Both channels has sound.

Thx for nay help in advance, Paul.