Hello,

I am trundling right along with my Neurochrome LM3886DR amp build, and I am at the point where I need to start wiring things together.

(red and black wires sort of mock up the input signal path)



What is the prefered method of wiring single ended inputs to an amplifier board?

The two options are, Mogami 2330 shielded microphone cable or plain 'ole twisted solid core 22g wire.



Shielded is a little more difficult to wire up, but is "supposed" to be better. (don't be too critical of the ends on the wire in the photo, I was just playing around, I know the ferrule should be pushed up to the insulator of the centre wire)

Twisted 22g solid core wire is super easy to deal with for soldering and "stays put" when bent where it needs to go.

Like most things I do, I am sure I am overthinking this, and either solution would be fine as I have seen both examples used. I am also pretty sure I would not hear a difference, but I would like to use "best practice" even if I won't notice the difference.

Thoughts on one vs. the other?

(I did lots of reading on this forum about this topic as well as general Google searched and I am still on the fence)

Thank you,

David.

I am looking to venture more towards a 300B dual tube per channel integrated amp for its sound preference and lower plate voltage. This dream machine might weight a ton after its done but that's fine. If I can get some suggestions with a rock solid simple design circuit with an excellent set of transformers that would be great. Integrated amp is always my personal preference. A dual tube mono block can be a last option. I saved up a handful of preamp, rectifiers and 300b power tubes. Any takes or suggestions will help be great.

Hey guys,

I've recently thrown a KAB-BE battery board onto my build with KAB-250v3, although since it's run out of power I haven't had any luck charging it.

It recommends a 19V 1.5A power supply to charge it, the closest thing I could find is a 1.66A. Regardless, Ive tried to charg overnight and I still don't have any power.

Any ideas what could be wrong?

My only hypothesis is that you're meant to connect a charging cable directly to the battery, although the only wiring setup I could find similar to mine had power go into the amp.

Thank you!

Why do my active speakers sound better with my PC as a source compared to a Denon AVR-E300?

PC motherboard is a Gigabyte G-Z170N-Gaming 5. Line out from the PC is a 3.5mm to RCA breakout cable. The RCA ends plug into a Dayton Audio DSP-408. Speaker wires run from DSP-408 to active speakers. (JBL 305P MkII, also tested with a DIY set of active speakers.) With this setup the speakers sound fantastic.

However, if I use my Denon AVR-E300 the active speakers -- both sets -- sound terrible. Attaching passive speakers to the AVR-E300 sounds much better, but not even close to the quality of the PC to active speaker combo.

As an alternative to the Gigabyte motherboard I have also used a Topping E30 to bypass the motherboard DAC through a USB connection. I did not notice a difference between running active speakers on either the PC motherboard or the dedicated DAC. Sounds the same to my ear.

Does anyone know why a PC motherboard would sound so good and an AVR would sound bad with active speakers?

Hello everyone, I’m new to the forum so I really hope I’m posting this in the right place. I am fairly new with car audio but I am familiar with working with electronics/basic multimeter functions as I work with them a bit at work.
So I recently took this amp to a “repair shop” and after I got it back one of the channels is still not working. After speaking with the guy of the repair shop who supposedly didn’t see anything wrong with it after he bench tested it he told me I should sell it and get a new amp. I originally took it to him because it was not powering on which he did fix. I don’t plan on taking it back to him.
Anyways, I tested the amp In my truck myself to find the issue. Power is very good (4g wire) 12.8v at the battery the same voltage on amp. Ground is on bare metal and getting a 0 reading on meter. Remote is coming from radio also working fine.
When I wired up all my speakers 4 + sub the amp was shutting off when I turned up the volume not even too high but I would say a medium volume. Took off all the speakers and tested each speaker terminal one at a time. All work great no issues except for 1. When I turn up the volume or gain on that particular terminal the amp turns off, it will come back on but I need to shut off the remote and turn it back on. I changed rca’s issue still there. Used multiple speakers, issue continued. So I’m pretty sure problem is in the amp. Again this is with only one speaker hooked up to the amp in that one particular terminal. I get sound from it but can’t turn up the volume very loud.
I hooked up my speakers to all other terminals without anything in the “bad” one and amp played fine and loud.
I opened up the amp and very thoroughly looked at it but I don’t see a sign of anything burned or blown. Can someone point me in the right direction to what I should be looking for here? Or what I should do next?

A have one of these critters on the workbench that has let the magic smoke out badly. Unfortunately it is somewhat different to the other 8000 series on Elektrotanya. Can anyone help me out with a schematic please.
Thx, M.

___SOLD___

Hello,
I sell my rack najda system.
It works perfectly, I've been using it for 3 years without problems, I include the remote with it.
It's powered with a SMPS which works great.
On the picture you can see XLR connectors but the outputs are unbalanced. The connector panels can easily be changed for RCA's.

___SOLD___

An estimate is what I am looking for. Housed in a Sonance 1250 power amp a Multizone amplifier 50w into 12 channels or 150w x 6 channels. The rear says 1200w. I guess this might be a 1.2kVA unit? There is no wiring diagram or mfg seal/ logo, just a generic part number with no reference.

Size wise, it sort of checks out... I have 2 other Toroids for comparison.

T1 is Antek 1kva
T2 is Toroid Inc (Now Noratel) 725va unit
T3 is the Toroid under investigation...

.

.

.

Hi,
12DW7/ECC832 contains 1/2 12AXT and 1/2 12AU7.Do you know a dissimilar triode which contains 1/2 12AT7 and 1/2 12AU7 ??
Thanks

Franco.-

Im redesigned (most closer orginal diagram) luxman m02.

Hi All,

Need some help/information on this USA made Transar/atd Current Source Power Amplifier....

Looking for any information and a schematic....

There was a short thread on this started on 2011. My Danish friend Erlend commented on this in 2014, but now the Amplifier has shifted owner to another of my friends, and I promised him to try to gather some info on this.

Ok.

Let me try to express this properly.

It's a bit complicated and multi-faceted.

At this point I'm casting about for a new DAC.

I've been using a PCM63 based dac with a x-coupled Jfet/Mosfet buffer for years - it sounds very good. I listen via a very clean signal path, only a passive discrete"L" attenuator between it and the amp(s). Speakers can be Quad 57, Acoustat III (modified), wide range horns (~250Hz --->~14kHz) with high bass driver + BEAR Labs Quadripole subs (using Crown MacroTech 2400). Amps usually are my Symphony No.1 amp or BEAR Labs SE Mosfet amps (with the Quads mostly). Friends bring tube gear over, so I have that reference point. Easy to hear what "guest" amps, or other gear is doing... very. A rather relaxed and natural sound, not "hot", not "bright".

So, I'm looking at the Soekris 1102 thread, back when it started. Thinking, hmmm, interesting. Forgot about it. Until a few days ago. Then I realized that I had missed everything, and that there were now assembled boards for it. Also had come across the Schiit stuff, and some others that seem innovative.

I also see that Soekris is making a DAC product complete as well, same basic topology, all-in-one with a discrete output buffer (surprising).

I'm wanting to get a handle on both the sound and if it is worth the effort to DIY.

Frankly reading quite a lot of the thread(s) it seems like the Soekris DIY build is not simple and is complicated by things like thumps, outboard uproc controllers, displays, upgraded power supplies, etc, etc. That makes it a BIG project costing maybe 2-3x the board itself. That puts the hardware cost in range of some commercial DACs, before considering the time it might take to build it up.

Then, I'm thinking maybe I can slam the 1201 into a box with bare bones supply run it "naked" and see... but what will that sound like compared to the fully decked out builds?? How much difference? Any?

And sonics, what's the diff between V1,2 and now V4??
Does V4 not need the muting circuit??

But then too, I have no way that I know of to get an audition with the commercial DACs either. 🙁 Or the Soekris for that matter!

The other thing that I think I noticed is that the absolute values of the specs and the look of the FFTs are not utterly spectacular at all?? Seems to me that I recall seeing an order of magnitude lower THD values from previous generation chip DACs?? Am I imagining this?

So, I am hoping for a discussion regarding all of these factors. Especially, IF you're running a Soekris DAC, I'd really appreciate hearing your sonic impressions - hopefully in the context of your system, listening preferences/experiences, and possibly comparisons with other units.

Anyone have a built up unit they might wish to sell or ship for an audition?
(I'm in upstate NY, just in case you are not that far away (NYC <---> Boston)

Looking forward to hearing more...


_-_-

After digesting a long thread about waveguides, some large and going quite low, I was thinking about building something with one. And if big enough, with large woofers, maybe no need for separate subs which are problematic in the space I want to rework next. So typically you end up with a horn in the top part of a tower with some big PA-style woofer below, maybe two. Blah. Or put the woofers on the sides opposed...still not attractive, and not practical for the space.

Then a little thought popped into my head. What if the woofer(s) were on the BACK, facing the wall? Yes, myriad problems come up:
(a) Getting the horn to go low enough...this implies probably a larger horn than there's really space for 🙄
(b) Finding a woofer setup whose radiation would need to be essentially omnidirectional to a pretty high frequency.
(c) The slot between the woofer(s) and the wall could make a resonance. Perhaps some kind of splitter or phase plug could be applied on the back to reduce phase cancellation?
(d) There's a time alignment problem between the horn and the woofers. Maybe with the right AVR* the AVR could power the woofers and in parallel from preouts power external amps with ideally crossover and time delay to power the horns?

What other problems and hopefully solutions can y'all think up?

P.S. If you are objecting that "the speaker isn't backwards, just part"-yeah, you're right 😱

*Yes many amazing solutions are possible with all kinds of multi-box solutions, miniDSP etc, but that's not something this friend would want to get into at all.

For a while now my main stereo loudspeakers have been using a pair of Peerless 830452s in a H baffle. These are very similar to the bass configuration used in the Orion as designed by Linkwitz.

What I have been considering, is doing away with the H baffles entirely and building 4 small infinite baffle cube shaped subs, with 1 XLS per cube. This would allow me to make use of boundary reinforcement and room gain.

The end result would end up giving me greater in room extension whilst requiring less power. Another benefit would be that the main panels would no longer be 'excited' by the vibrations caused by the H baffles that support them.

I know that Earl seems to recommend 3 subs, but this is in conjunction with the main loudspeakers, giving 5 individual sources.

Without the H baffles the main panels extend down to 100hz.

I don't have much, if any, experience at integrating subs into a system and am wondering if there would be any problems in trying this out?

I've wondered for a long time about that old bone of contention "does the speaker load ever appear less than the DC resistance."

IIRC it was Matti Otala who first said an 8 ohm speaker could transiently appear to be 1 ohm
AES Convention Papers Forum >> Peak Current Requirement of Commercial Loudspeaker Systems
which led to Harman-Kardon's "high current" receivers and amplifiers.

But then a later paper-which I very unfortunately do not recall the authors of-said "well, Otala's data was only from simulations, we find no actual evidence of the loudspeakers transient impedance ever being lower than the D.C. resistance"

I'm wondering if anyone has ever tried measuring this* or knows of any other evidence about this?


*I had a scheme where I wanted to rig up a data-output voltmeter across the speaker, another across a 0.1 or so ohm resistor in series to the speaker, then play actual music. Each second or whatever, record both values into a computer, which would then divide the two to find an impedance magnitude. But then I changed jobs and that never happened.

Another approach might be to calibrate a storage oscilloscope running an X-Y I-V plot-the slope of the line for a sine wave would be the impedance, so presumably you could look at that and see if the slope ever goes past the DCR value (which you could calibrate with an actual resistor).

Both of these idea may not be quite right-I haven't thought about this for a long time.

Hello
I have a question and maybe a favor to ask
Who here uses or had any tv tubes ?
Don’t some tube amps use tv tubes ?
Reason why am asking for some free ( donated ) TV tubes, is I acquired a mint ,technicians vacuum tube rejuvenator , for TV tubes. And is like to give it a try to see how it works.
It’s made by B&K , model 465 CRT tester
So if anyone can help, I would really appreciate it. Please send me a message or post openly about your knowledge involving TV vacuum tubes in an audio circuit of amplifiers

So this is a flat indoor antenna. It is very good. Brings in stations very clearly on my Dynatuner FM3 which is not known for exceptional sensitivity, as good as a dipole on my Tandberg 3001A. The FM3 does not do well with the dipole. I'm just curious if piggy backing two of these would be even more powerful?

Good morning,
I found 2 audiobahn aw1206t subwoofers in my garage. I have never rebuilt a subwoofer, but would like to try. I was going to use the baskets but need help to find replacement parts. I already know I'm going to get **** cause they are audiobahn, but instead of throwing them away, I want to.use them to build and learn.

Guys

I'm building an S/PDIF switcher with Twisted Pair's 4:1 Mux/Demux board and I'm wondering what wire to use for internal wiring between the board and the RCA connectors (±10cm each). Do I realy need coax for this or can I get away with something else?

Regards

Im looking for speaker /maybe full range/ for RCA Victor SA-20, 8 inch.

For sale a pair of NIB Ciare NDH 15-4S 8 Ohm loudspeakers.
New, never used or connected, in original boxes.

Price: 450 EUR

Shipping from Kazakhstan, 60 EUR to Europe, 70 to Americas, registered airmail with tracking.

Buyer pays paypal fees, offers are welcome.

I don't think bringing the name BOSE might go well with people!

But, there are some decisions which makes me wonder why they are taken and the benefits which it might bring!

As title suggests, I'm still wondering the decisions that went through when these speakers were finalized.

Why use a dual opposed driver for full range?
What advantages and disadvantages does this setup bring?
Can this work on any other driver?

Your thoughts please?

(Attached the image just for information! Credits:BOSE)

Hello, Everybody.
How are you doing?


I'm designing an STK4231II amplifier, with an original part that I have for more than 20 years and never used (precious! 🙂. Just to relax, rsrs.
I started with the Sanyo's reference design, to calculate gain, poles, bandwidth, protection, etc, with further reading of some services manuals, just to see what there is out there, and I found something curious that I can't explain well. On the services manuals (more than one), the designers have placed a small capacitor across STK's inverting and non inverting inputs. After some matlab and LTSpice, this capacitor creates an additional pole at around 40MHz, using an ideal model of an operatinal amplifier.
Does anybody know the reason for this spending? Maybe for susceptibility compatibility? The designer has placed this small capacitor across all the operational amplifiers he/she used in the equipment

Hi i need help with this amp everything is working but no switching on the output section

Boy, who knew 'cosplay' was such a large business (search for 'EVA foam')!

I have several cabinets to make with 12" speakers (12.2" outer diameter).
These are FRFR cabinets, speakers are front loaded and I need material to make gaskets out of.

From reading other posts EVA foam seems to be the way to go. I am looking for EVA foam that is soft enough / suitable for gasket material ('cosplay' EVA foam seems to be to 'hard' for this purpose). 'Craft' type sheets seem to only come in 12" x 9" sheets with unspecified hardness.

Anyone know where I can get EVA foam wide / tall enough to cut gaskets from?
My preference:
-- 1/8" thick maximum.
-- 'Rubber Band' softness (Shore A: 20, Shore 00: 20).

Or anyone with other ideas for gasket material (No tape, whether striping, or 'goo' type material. I want to cut the gaskets from sheets) and possible suppliers would also be appreciated.

I am in the U.S.

Thanks.

I have a very nice Heathkit IG - 37 for sale. This unit works fine and comes with a very nice factory manual, plus both factory cables. The very hard to find 300 Ohm twin lead connector that plugs into the front of the unit is included. The 300 Ohm twin lead still has the factory alligator test clip setup, that connects to the tuner's external antenna posts also. Price is 125.00 US dollars, plus all shipping/tax costs to your doorstep. No Paypal. TIA

Hey everyone!

Disclaimer: I'm fairly new to diyaudio, amplifiers, power supplies, schematics, PCB design and everything that this forum touches on (read: noob), so I urge you to be patient with me - I am eager to learn though.

That being said - Hi! My name is Mladen 🙂

Anyway, on to the point: Recently I came across @xrk971 thread Hakuin SE Class A HP Amp which got me interested into building my own amp (PCB design and everything).
But, since X hasn't opened source his power supply schematic I decided to tackle that on my own (without some extras he implemented). Basically what I tried to do is: Battery Charger --> Boost Converter --> LDO.

Spent last few days reading through data sheets and reference designs and this is what I came up with. I would greatly appreciate if you could fact check the schematic and suggest things I should do (things that I've probably missed).

I plan to use Samsung's EB-BJ710CBE battery (if possible).

Data Sheets:

MCP73871, TPS61178, TPS7A470

I have to sell Brand new dayton Spa 250 dsp plate amplifiter
price $100 plus shipping

best regards
myintv

I have one of these in for repair that has been modified......anybody have a schematic please ?.

Eric.

Empty Munro Egg 100 enclosures going cheep on Ebay UK!

From what I can find out, they are normally populated with Peerless by Tymphany BC25SC06-04 tweeter and possibly the SDS-P830855 4".

I've bought a pair, I think I'll put Monacor MSH-115 and a cone tweeter in using a shaped MDF baffle or two.

Pair of Egg Shaped Speaker Housings - Colour Red - (24) | eBay

I have the Sherbourn PA 7-350 power amp that I bought from Emotiva when they had the clearance sale. This is a really solid and well built amp but it randomly shuts down due to its protection circuit kicking in. Sometimes I can watch a whole movie without a problem and sometimes it shuts down in about an hour. Here are things to note:-

1. The shutting down is not related to volume, it can shut down even when nothing is playing.
2. The shutdown is not due to overheating problems as the amp is in a well ventilated place.
3. Shutdown is accompanied by mainly the channel 7 lights blinking which id the front right speaker with occasional channel 6 light blinking which is the side right speaker.

Remedies that I have tried:-

1. replaced my XLR cables between pre/pro and amp but it made no difference.
2. Replaced the speaker cable for both those channels but no difference.
3. Swapped speakers to rule out any speaker problems but nothing changed.
4. Swapped the XLR cables to ascertain if it's my pre/pro but no change which means my pre/pro is intact.

Things that I will be trying:-

1. To disconnect all speakers and check wiring to rule out lose connections on all channels.
2. Bypass the 20Amp mains power stabiliser/conditioner that feeds the amp.

If anyone has any experience with such matters then help will be appreciated as I'm still in the process of trouble-shooting.

I'm wondering if there are other members of this forum who are using the same power-amp.

I'm hoping that it is not an over-sensitive protection circuit - any electronic enthusiasts or engineers here that would know how to resolve this?

Wood chips/shavings from woodworking machines is easily available in my locality. I would like to ask whether packed woodchips/shavings can serve as echo mufflers like fibre glass slabs? The reason for asking is ease of purchase and price. Please, be aware I am not after making studio for professional use but only a room for music play back without dominant room modes.

My idea is to use carton boxes of medium rigidity, cut them in the shape of prisms, and fill them with woodworking chips compressing the latter with my hands. That way, I should reach a certain density.

What do you think? Room modes are still ruining some music tracks and these tiresome modes seem to be sensitive to air humidity and temperature.

Hi everyone,
I've just posted my introduction and here's my first thread on this great forum.

A few days ago I aquired an Audio research D90 (not a D90B) which is populated with Electro Harmonix KT90 power tubes and an EH 6550 regulator tube.
The amp was in a doubtful condition:
-aged soldering connections (already solved since yesterday)
-Lousy aftermarket loudspeaker sockets (I fixed it up to the point where at least it's safe to operate; should do more later)
-It was badly mis-adjusted. (especially the DC balance was farrrrr off...

I did a full adjustment as per the guidelines of ARC and found the amp to be working well, with a few things I like to ask advice on from more experienced users:

-Heat: Even without the top cover, the power tubes get blazing hot. And not only them, the power transformer gets very hot as well. (too hot to touch after a few hours of playing.) Is this normal?

-With the above, please note that I biassed the KT90's on 65mA (ARC suggestes an even higher bias of 75mA. Would this make a big difference on the sound?

-The power transformer is buzzing / rattling loudly. I can hear it through soft passages in the music. I'd like to make it more quiet. Plastic spray came to my mind, but I think that given the temperature of the transformer, this isn't wise. Any suggestions?

Thanks for reading this 🙂 I'm looking forward to know ya all a bit better and to get my D90 in perfect shape as well.

hello,

what do you think of this design for a vented concrete box?

the driver is Tang Band W8-2145 8"
spec-sheet
the box volume is ~ 5550CM3

can you help me figure out if the box volume is big enough and what are the port measurements?
and one more question, would you use a close or ported design for this driver?

I'm building a pair of subs each with 2x Dayton Audio SD215A-88 8" drivers and a single 4" flared port.

With a target volume of 3ft^3; I'm wanting to make it roughly the same footprint as my Infinity Towers, which is 12" deep (outside). If I assume 1/2" MDF/plywood and a double baffle, that gives me 10.5" deep (inside), but with my port flush mounted, that gives me 11.5" from the front baffle to the inside of the rear wall. My 4" port (actually measured 3 15/16") needs to be 8.5" long to produce the tuning I want (31Hz) plus the flairs. The flairs are 1.25" each end or 2.5" total, so my total port length, including flanges, is 11". That only leaves me 1/2" of space between my rear flange and the rear wall, which is obviously not enough space. If I bump my depth to 14", I have 2.5" of space to work with, which still seems a bit tight to me, but I'm not really sure why.

My question is, how much space do I need to leave between the rear of my flange and the back of my speaker box to avoid unwanted effects? Is there a general rule of thumb with or without flairs? Is it based more on air speed than anything? If it matters, I'll only be pushing 100w total through both towers (50w per tower), so at 50w each, that a port velocity of 16.5m/s. If I were to hook it up to a bigger amp and run a full 160w through each tower, that would be 30m/s.

I built the temperature compensated LM334 current source (Figure 1 below), configured for 5.5 milliamps: R1 = 27R and R2 = 270R and D1 = 1N457A. When I put it on the curve tracer to sweep out its I-vs-V curve, I got quite a pleasant surprise: the LM334's "knee", where it ceases acting at a current source, is at a relatively low voltage: 2 volts. See Figure 2.

Linear Technology's datasheet suggests adding a JFET with large |Vpinchoff| as a cascode (Figure 3). I tried this, using the J105 device (Figure 4). It only moved the "knee" upwards about 200 millivolts or so, maybe to 2.2 volts: Figure 5.

I was pleased.

diyAudio members who have created an LTSPICE model of the LM334 and the J105 and the 1N457A, may wish to simulate these two I-vs-V curves and see whether measured data matches simulation results.

_

Hi guys,

What's the difference between a Threshold SA/30s and a SA/3.9e apart from the typenumber?

Thanks in advance

Does anybody know the loudness specification of NAD 3020? I couldn't info about it although found many schematics or service manuals on the internet. I'd like know what frequencies does its loudness boost and how much dB of boost? Thanks in advance

closed

Bought a pair on parts express deal of the day. Wanted to put them in sons truck. Decided to play around with them first. So used them to put some time in on my new printer. I am very impressed. Sound great
Especially vocals for such a small setup. I find they breakup a little up high if anything. Thinking about printing a single box for 2 when I reprint these. Make it a portable speaker.
If only I can figure out a micro sub to go with them fir just a little extra.

When driving a speaker on a long cable, what is a safe capacitance to design an amplifier to be stable driving? Would 10 nF be a sufficient maximum capacitance or 100 nF? I measured some audio cable at about 400 pF/m, but I would guess that the variations in setups might produce higher capacitance loads. Are audio amps ever designed to be unconditionally stable with respect to capacitive loading, and if so, how? Given that oscillation of an amplifier could produce a catastrophic effect on a speaker if the amplitude was high enough, I would think this might be a consideration to maintain SOA.

Hi All,

Fairly new here 😁 thought I'd share here some of my story repairing and restoring a "parts" HA-4700 from TradeMe. If anyone's interested.

When I got it, the lights were on but there was no output at all.

What I found was one channel with the output emitters sitting around 8v, the other at the + rail more or less. Dead output on that one I thought. But it turned out that every single 1/4w "fusible" resistor in the thing was either high Z or open. This was the same problem as was found in the excellent YouTube video by JoulesperCoulomb which was what prompted me to start checking them.

Replacing them all with standard metal film resistors ("fusible" resistors in those values proved hard to come by and normal metal film resistors should work well enough at failing open if need be) brought it to life except for a several megahertz oscillation (another problem also found in the video! These must be reasonably common issues) which was due to some of the (weird) axial caps gone bad. Replaced those with mlcc type and that sorted it! Adjusted the bias and DC offset and was away. A few dry joints fixed along the way and of course new thermal paste for the power trannies.

Knowing it was serviceable, I moved onto cosmetics, restoration and tidy up. So far
* Replaced 8200uF bulk caps with 10000uF CDE caps. They actually tested fine at over 7000uF apiece but 8200 seemed kind of small for a 50W amp anyway.
* Replaced dead "TAPE" bulb with yellow LED
* Replaced incorrect 1N4004 diodes on indicator/selector board with the correct 10v zener
* Removed case bottom for corrosion and paint repair

Still to do:

* Replace other indicators with LED
* replace a switch I broke 😭 which is going to be tricky
* polish up the chromed buttons and knobs best I can, they're a bit corroded (green spots)
* Clean up rust on case and repaint
* Clean up rust on transformers and paint
* Receive new volume knob (was missing)
* Reassemble!

If people are interested I have loads of photos so... Let me know if you wanna see them.

Here's some pics of the state I got it in... Fairly rough:

"Parts" Hitachi HA-4700 Original State - Google Photos

Good Day to all. I am about to repair my personal JL Audio 1000/1 again, that I had repaired twice before over the 5 years I have had it. The first time it went out when I mistakenly wired it to 1 ohm combined with low voltage, and the second time I believe it was low voltage alone. I will start the repair thread by first asking for help to select the PS FETs and outputs.

PS FETS: The amp originally had IRF3707 in the power supply, and I used IRF3709Z both times previously. I am unable to find IRF3709Z available at this time so I am looking for advice regarding what I should use. Using alltransistor.com equivalent chart I personally think IRL3103 would be a good substitute as the specs are very close to the IRF3707 according to the attached chart. Digikey suggested the IRLB8721PBF as a substitute. The gate resistors were changed to 22ohm to work with the IRF3709Z.

OUTPUTS:. Don't know what was originally in this amp as the previous owner had tried to repair it with IRF540. I had used IRFB31N20D both previous repairs. What would be the best choice for outputs this repair?

Hello all,

I am starting to dabble in a active speaker setup, using a Xonar U7 MKII for a simple active 3 way mains, 2.1 setup at my desk. I am wondering, how someone would setup a 5.2.4 setup for an active home theater?

Are there any 15, or 23 channel devices that cost less than my house? Is that what would be required?

Is there a way to use multiple Xonar U7 MKIIs without having huge timing issues?

A more realistic idea, how would someone "actively" control just a center speaker in a basic AVR setup? Or just the left, center and right?

Sorry if I am using the incorrect terms. Pretty fresh on my DIY audio adventure.

Thank you.

Ive been wondering, for a while, why so many people believe the audio myths and why theres so many. Always had the feeling the internet was at its root. Now I have some evidence.

The Social Dilemma | Official Trailer | Netflix - YouTube

Fake news spreads 7 times faster than the truth. Everyone has there own truth, and since it makes money for the rich this will continue and get worse. When people get there "facts", that are customized per individual, from social media what do we expect. How have we become such sheep?

I hope Ive enticed a few to watch, as they say the cure is knowledge.

Hey everyone.

I am in the process of designing my first tube/SS hybrid.

The original idea was a single ended design, but for the price of another tube and a couple of resistors and caps, push pull becomes an option, no?

This is the preliminary design.

If I understand it right, this should work as a class A push pull amp putting out about 20W? I could also change the top 6N3P for a 18k resistor to save a tube I think...

Koda

I have a 1971 Fisher S-695-IP console, with the following speaker compliment per side:

Qty 1 - 12” Rola woofer, 8 Ohm
Qty 2 – 5” Rola mid-range speakers, 8 Ohm each, wired in parallel (effective 4 Ohm)
Qty 1 – 3” CTS tweeter, 16 Ohm

The crossover is comprised of the following:

Woofer: 2.6 mH air coil/inductor
Mid-range: 5.6 Ohm resistor, 25 uF capacitor, .5 mH air coil/inductor
Tweeter: 4.7 Ohm resistor, 4 uF capacitor


Since the console is now 50 years old (wow how time flies! ) the old capacitors in the crossover are due to be replaced. And of course normally that would be all that is required, especially if no changes in crossover design or driver are to occur.

And normally I would approach this simple rehabilitation with the intent to make no changes and keep the design and drivers as manufactured by Fisher in 1971... effectively just replacing the capacitors with the same values and move on.

However, I have a few observations that lead me to consider modifying the crossover and replacing the tweeter with something more modern.

Fisher speakers are known to be voiced, as many manufacturers do, for a specific style and taste. Fisher was known to voice their speakers more toward vocal, classical, and jazz versus many of the styles that are popular today. With that in mind it seems from my listening and other subjective reviews that Fisher speakers seem to slightly mute or roll off the upper mids and highs a bit to perhaps “soften” the sound. And this does seem to be the case subjectively when listening to this 1971 Statesman console.

In addition, the use of 3” paper cone tweeter likely plays a part, even after replacing the capacitor, and noting that prototyping its replacement with a small soft dome really pleasantly brightens up the sound.

So, my first thought was to replace the OEM CTS 16 Ohm paper cone tweeter with a soft dome. But finding an appropriate new 16 ohm tweeter is challenging, and I found none except for a very expensive horn that isn’t a good fit in several ways.

But that’s not a big deal theoretically of course, as I simply need to modify the capacitor for the tweeter to accommodate an 8 Ohm modern tweeter, and leave the rest of the crossover alone.

However, this is where I am asking for some expert analysis of the OEM crossover before I change anything.

If I run the OEM crossover points through some online crossover calculators, it seems that the factory advertised crossover points of 2500 & 400 Hz may not align with the capacitor and coil/inductor values that are actually installed. There seems to be a big frequency gap between the mid-ranges and tweeter, and it takes choosing some wildly different crossover values to make the OEM capacitor & coil/inductor values to get even close... but not at the same time.

But I’m admittedly not an expert crossover designer, and along with the capacitors & coils involved, there are also a couple resistors in play.

I know that typically a resistor in a crossover may be used to attenuate a driver, and normally isn’t used to change the impedance of a driver, but I do wonder if perhaps it has a slight effect on impedance and thus influenced these crossover capacitor & coil/inductor values in a way I don’t understand and the online calculators can’t take into account.

Also, I realize that we don’t know a lot about the drivers themselves other than the impedance, and obviously the manufacturer did have that data. So that leaves us at something of a disadvantage, but really in this case I’m only concerned about the mid-range and tweeter portions so the bulk of the T/S parameters probably aren’t that relevant.

But sensitivity is relevant, however without objectively testing the drivers or having their specifications we’ll likely never know, but I can say it is likely that they all are high sensitivity given their vintage and the relatively low power (30ish wpc) of the receiver.

Whew… OK 🙄


So can someone with some crossover expertise look at the OEM design and try to explain how it is working to deliver the specified 2500/400 crossover points, or discern if there are any issues with that design such that is is not delivering the specified (or more ideal) crossover points and if so what component values should be modified?

And with that in mind, and my plan to replace the 16 Ohm tweeter with an 8 Ohm tweeter, what component values would be appropriate to change in the crossover?

Thanks in advance!

First of all hi, pretty much an absolute beginner here.

I'm just starting to get into amplifier design, and the variety of parts is somewhat... overwhelming. I guess I could semi-blindly pick, but I thought I'd use the wealth of information on this forum to ask:

What're some decent, generic parts that you'd recommend keeping in stock and using for designs? Nothing hugely special, expensive or obsolete. Stuff like small signal transistors, some complimentary models, some output mosfets. Capacitor brands you trust or have had good results with, or other devices like voltage regulators if they're not too specific to the application.

I'm sorry for the hugely vague question, and thanks in advance!

I hadn't heard of these. Interesting but require a lot of real estate.

Fort Smith Man Revolutionizes Speakers - Entertainment - Times Record - Fort Smith, AR

I built a tube preamp in one of those Radio Shack plastic boxes and not sure about a couple of grounding issues. It sounds pretty darn good but does have a slight hum. So questions,
1. I used a chassis mount IEC so not sure where to put the safety ground blade
2. I used back to back power transformers, I'm using 6922 tubes and running them in series at ~12vdc. Not sure what to do with that center tap. (Attached)
3. I didn't use the shield pin (9) of the 6922 tubes. Should I and where would that go?
Thanks

Two Denon POA-6600 (220VAC) mono blocks available for parts. Cases (front faceplates still available) and heatsinks are gone.

Offers plus shipping from Canada.

My other sources (CD, DAC, Bluetooth, etc) all have an output of 2v

Should I set the gain of the phono stage to 2v to match the other devices?


I have a MM Phono cartridge with 5.5mv output (Ortofon 2M Blue).
To match the other devices (2v) I would want 51 db of gain.


Thoughts?

How is a bias sense transistor chosen. I sometimes see TO-126 type devices with medium hfe (100-300) With vce 120v to 180v

What are the parameters that are relevant?

Q2: In a conventional EF design, how much of the rail is the CE of the biasing transistor exposed to ( eg the Vas, Drivers and OP may see the full rail to rail voltages, is this true for for the biasing bjt too?)

I ask because I am playing with a kit and at lower rails, (+/-60v) the 2sd669 biasing transistor has no issues, but as I raise the rail, it blows along with the OP and drivers. The rails are 85vdc each in this scenario, well within the vce of the drivers and the OP ( 180 & 230 respectively) but over the 160vce off the 2sd669.

Thoughts? Should I replace it? I do not have the schematics of this kit, and I know I am asking a lot

For Sale: Two SED Svetlana Winged C 12AX7 "silver boxed anode" tubes. These are not the recent reissues. I purchased these from Langrex December 2017 and put them in my amp to verify that they work. I have not used them since, so they only have a few hours on them. I have not had a 12AX7 amp for a while or a way to test them, but they worked fine when I did use them.
$35 shipped for the pair in the continental USA.

I need to replicate a Sziklai pair in a power regulator .The original pair is comprized of a 100mHz driver for a 15 mHz power trz.I only have 5 Mhz, 8 Mhz and 180Mhz power transistors at hand to replace the original.Which one would you choose?

FS: Diytube ST 35 rev b board with chassis. The board has been populated but has bad soldering and previous owner drilled 2 holes into the pcb located in front of the board. The chassis holes are not lines up and will need to be fixed. This needs work to fix the bad soldering job.

Pls see pics.

Asking $40.00 plus shipping. Sold sold sold

For the first time in my life I’m building a crossover with pretty expensive capacitors. To keep them close, I plan to solder 1 leg close to where the axial lead comes out of the next. Is there any danger in getting it too hot? This is poly film cap. Just for knowledge, how do other types of caps handle heat from soldering as well?

Normally I don’t worry about it and everything is fine but just want to take extra care here....

Hello All,

Looking for a Knight Kit KG-620 VTVM.

Does anyone have one they don't need
and would like to sell it?

Hi,

I've just finished building my new desk, and have enough timber to make some nice matching desktop speakers.

I want them to be small, full range speakers, generally for watching movies, YouTube and some background music (I have headphones for serious music listening).

My main question is, can I power a set of 3"- 4" speakers from my headphone amp?

The amp in question is a Trilogy931, relevant specs :-

Input Impedance ≥50K Ohms
Gain (max) 18dB
Frequency response 20-20KHz +/- 0.5dB
Output impedance ≤ 10 Ohms
Output Power 800mW into 60 Ohms, 200mW into 300 Ohms
Distortion (THD) ≤ 0.05% 10mW into 300 Ohms
Signal to Noise Ratio ≥ 85dB A Weighted

After looking at other threads here, I've gravitated to either the Alpair 5.3, or the Fountek FR89EX

Would that amp power those ok?


Thanks,


Steve

Hi,


I can use 4200R instead 3500R with this circuit?


DIY Single-Ended (SE) 6L6 / 5881 Tube Amplifier


And why they said 15W? The 6L6 only out's 6W in SE.


Thanks.

I'm building a "transportable" battery powered dac+amp combo. The energy source will be one or two 14.8v rechargeable batteries (the ones jumbled together in the form of a square)

As far as I'm aware, power supply is one of the most important components of the analog sections. I'd like to know the list of battery types and their load driving capabilities so I can start designing the power supply network.

Online searches lead me to multiple competing opinions. One says batteries are better suited to constant load. Another says batteries are better suited to pulsed load so that the space where it doesn't operate gives buffer for the depletion region to regenerate. This is apart from the linear models where we have internal resistance models etc.

I'm not super well versed in batteries, but I kind of have two approaches I can think of. In case the battery can sustain a load very well along with transient powers, I could be using a LDO + some filtering and that would be it.

If not, I shall be using two batteries and a switching logic + active components to generate somewhat kind of an AC like waveform (one battery doing positive, one doing negative) and then an active power filter+ rectifier to generate stable dc. Since a single battery is not operating continuously, it might be able to get more stable if that aberration exists, and make the non linear issues of the batteries disappear when seen at the power input end. I could also possibly recharge the battery when in use without disturbing fidelity. The rectification circuit is present in my burson fun where it does a switching operation at about 170khz and then rectifies it, hence pushing any ripple noise etc well beyond the 170khz band.

I've been going through 8 channel ADC datasheets looking at the analog characteristics for a potential project and noticed that for low sample rates akm measures the 20Hz-20KHz response...but for sample rates above 48KHz, the measurements are in the 40Hz to 40KHz range.

It leaves me a little curious as to what happens in the low band when you operate the device at higher sample rates. I've attached an excerpt from the AKM AK5578 datasheet to show what I am talking about.

Would appreciate any thoughts as to why the different dandwidth measurements would be reported for high FS!

Hi all,
I've just bought a DAC which has 3 AC-in ports: AC15V-0-AC15V (15W), AC9V (10W); AC9V (10W). Can I power it with transformers like this?


This is my DAC


Thank you

Hi, does anybody have schematics for this amp?
One of the outputs of my ML-9 is down.
Luckily the whole amplifier has a current protection circuit in the main power supply. When I disconnect the +50 and -50 Volt for the faulty channel from the power supply the other channel works perfect.
I found out that some of the TO3 cased transistors are used for power supply regulation per channel, I suspect that the error is in that part. Having the circuit schematics would make it much easier.
Does anyone have any experience in repairing a Mark Levinson power amp? This model is supposed to be the smaller brother of the ML-3 and the predecessor of the ML-27 power amp, giving 100Wpch/8Ohm, (conservative statement, it delivers even 380W in 2 Ohm!).
The sound is still (or rather was) great and that for an amp built in 1978.

looking forward for any help,
regards,

Vincent

before starting contribs in this forum I would like to introduce myself:

My name is Gerhard, I am living in Germany and until my retirement I was working as an automotive electronics engineer. My hobbies are chess, motorcycle, electronic and... yes, Audio (esp. amps & loudspeaker).

My long-lasting back-brain audio-project surrounds the topic "Current-Drive for Loudspeaker (I-Drive vs. V-Drive). I intend to simulate characteristic params like THD, IMD, Step-Response, Bursts, etc. using tools like Matlab and Spice. All this with real loudspeaker loads.
Linear loudspeaker models are available and producing reasonable results.
Currently I am working on analysing methods and algorithms.

The benchmark shall include <10 linear amplifiers, which requires available schematics in gEda, KiCad or Eagle, to support netlist creation for Spice-simulations with "real loads".

The simulations will be restricted to the linear travel of the loudspeaker-cone. Extended nonlinear simulation can start later.

Are there already any contribution along this topic or is this a new question?
I don't want to re-invent the wheel.

Where should this project be issued within this forum's scope?

looking forward to your response...
kr, sepp2gl

GENUINE PETER DANIEL LM3875 CHIP AMP,BOARDS POPULATED,COMPLETE, WITH NICE 230 va TOROIDAL. JUST NEEDS FITTING INTO CASE PROVIDED.
PARTS COST A LOT MORE THAN ASKING PRICE.
£120 plus post to uk only(quite heavy).

Hi,

The preamplifier I am looking for is very hard to find but I'll wait. In the meantime I would like to listen to my CDs.

Neither my amplifier nor my DC player have a volume control, I think I need a passive volume control, something simple and inexpensive.

Any recommendations?

My experince in Hifi audio is quite limited and I have to say that I lack the proper words to describe what I'm looking for, but I will give it a try anyway.

I looking for pure, highly detailed sound, not too bright, not to warm- as neutral as possible, with a lot of presense. To give a concrte example, I listened to Luxman 505u and the sound was excellent for me. Unfortunatly the price is x3-x4 than my budget. I.e. my budget is around 1000 USD

I read few threads describing the AKSA amplifies as something which might answer my needs. However, the AKSA is not a DIY as I understand the schematics are proprietly.

I use Indiana line Nota 240 speakers, which are not very efficient (89dB), so power is important (e.g. DIY ~11W tube amps are not enough).

I'm not looking to play around with too many trials of DYI stuff, but hopefuly to invest my time in one amplifier which will sound best for me.

A popular design for which a PCB is already available would be prefered. I have designed and manufacured PCBs for many years and I'm not that excited to do it if a pre-made PCB can be purchased. However this is a secondary consideration. Sound/cost come first.

Based on my description, could you recommend what I should looking for?

Thanks,
Aviv.

Hello,

I am designing a 32 band band-pass filter bank (eurorack standards) which consists of a tube Class A 2 stage mono preamp sent in parallel to the 32 bands and summed by two (stereo) active busses (VCA controlled). In each band there is a VCA controlling the volume that has an aux output connected to the input for feedback controlled through a pot and a switch for on/off, there is also a switch to bypass the filter connection to work as a summing stereo mixer. Another switch is found in the master controls to bypass the preamp sending the signal to the bands and instead be sent on a separate external output to let it be used as a separate pre.

I have been reading on ways of using different types of switches for less clickiness or pops when engaged, but a transistor or a relay seem to have too many drawbacks (distortion, noisy) so I though of using something like maybe a quick envelope to mute the VCAs when the switches are used but I have no idea if there might be a better way to also minimize part count.

The VCAs I'm using are the THAT2180 with a logarithmic amplifier to bend (slightly concave) the CV according to the power law (still trying to establish that one 😀).

I would appreciate any feedback as I'm fairly new to circuit design, thank you.

I have a couple of cases that call for a small hex head cap screw but I am not positive about the size. Oh a 4x40 will fit but it feels a little lose is there another size perhaps metric with the same thread pitch but perhaps 1/100 " larger ?

Are they mains transformers with two equal voltage center tap secondaries ( 6 terminals at the secondaries ) ?
Or a variant four equal voltage secondaries ( 8 terminals at the secondaries ).
This is just to know wether this is popular or asks for a custom winding.

I have recently acquired a pair of these and i am currently looking for a design to mount them in , i have drifted towards folded horn designs for both SPL and aesthetics. I'm a total newby can someone point me in the direction of a suitable design, also is it necessary to redesign these basic designs to accommodate resonate frequencys and air volumes ? I have no idea.

Does anyone have high resolution pics of the power supply area of this amp ?

Someone has been it before

I just found a box of 9x 1N256 NOS in my stuff. I believe they are silicon rectifier diodes/Thyristors. They're really nice looking and have all the mica nuts and accessories. General Instruments JAKK 1958. I was thinking a power supply? What do you think?

Up for sale is a rare Victor TT 61 motor drive unit. I believe these were only sold in Japan. Runs on 100VAC, will include a step down transformer for an extra 20 bucks if needed. Unit runs great, it came with a Victor two arm plinth and I picked up a higher model drive unit. This sale is for drive unit only, no plinth. Shipping at cost. Price is $150.00 plus shipping.

BillWojo

I am wonder whats the differences in the sound we get from various types of SMD resistors.

Eg, I was told that foil resistors are the best, but they are also most expensive. We also have wire wound, thin and thick film resistors.

So, I am wondering if we are able to hear any differences in these resistors. Will a foil resistor sound very different from a thin film one??

Does anyone have a pair of Magnequest S-240 transformers they're willing to part with? I'd be interested in steel or nickle/pinstripe.

I'd consider vintage Peerless too of course.

Let me know!

Thanks,
Tom

Last purchase for SCM20 speaker. What you see is what you get.
Due to the weight, only sea ship available, est 2 to 3 months base on location. Ship from S.E.Asia.

USD800 + shipping. Paypal fee adsorb.