On the bench is a single-ended pentode (6CZ5). It’s configured with 36dB of negative feedback from the plate of the 6CZ6 to the cathode of the input valve. I dubbed this arrangement RDH733 after figure 7.33 in the Radiotron Designer’s Handbook. The RDH schematic shows negative feedback from plate to cathode in a two-stage amplifier. The input and output devices are both pentodes. The feedback loop does NOT include the output transformer.

RDH offers a mathematical analysis of the circuit to help estimate performance. The analysis is somewhat complicated by the feedback resistor Rk below the cathode resistor of the input pentode, which is not bypassed and provides additional negative feedback which reduces the input pentode’s gain. I used the RDH mathematics to put me in the ballpark and adopted a test circuit with potentiometers that allowed me to fine tune the feedback.

The chart shows total harmonic distortion on the vertical axis and output power on the horizontal axis for a 1kHz input signal. The orange line shows the result for a zero-feedback amp using the 6CZ5, the black curve with 36dB of negative feedback from plate to cathode. The negative feedback reduces distortion over a useful range of power.

I found I could get splendid test results (low distortion etc) that didn’t sound so good through my speakers. So I varied the overall feedback until I liked the sound, sometimes to the detriment of the measurements. As a rule of thumb, with my test speakers I achieved pleasing sound when I arranged THD to be 0.5% to 1.0% when the input signal was 1VRMS. The “sweet spot” will likely vary according to your speakers and your taste.

Hi,

I´m interested in buying Taylor T20 and TZ20 triodes, preferably within the EU.

Other high mu triodes with 7,5V filaments and UX4 bases might also be of interest, such as:

T40, TZ40, T55, HY40, HY40Z, 5514 (CBS)

Best regards,
Daniel

I was told to clean my messy mancave..and as you know stuff add up over years…. First round resulted in a new small se amp with SFR E130. This is Something Else. Yes I do not need the power or a new amp…but I can’t resist checking this one out.
I have not managed to find an audio amplifier buildt with rs337
Maybe there is a reason ?
Anyway initial thought is to connect it as pentode with shunt Feedback from plate to grid.
Does any of you have knowledge or experience with this tube?

Scroll down a little for datasheet

https://www.cdvandt.org/RS301-337.pdf

As max anode current is not given I would appreciate if anyone could share info about it.

Picked up a vintage receiver and was testing it and the balance knob appears to do NOTHING. I rotate it back and forth and it has no effect. Mono button is not pressed, tape monitors are set to source. All controls I believe are in the correct position. But I am playing with only one rca cable hooked up to the right channel input and yet the unit plays out of the right speaker no matter where the balance is set to. I have not cleaned it yet but could a dirty control really do this? Very Odd...

Hello,

As the title says I would like to buy one of these.
Would be great if we can do a trade with something that I have on sale.

Thanks.

Hi folks,

I am looking for a new pick-up for my Classe CDP-100: It is a Philips VAE1250,

I asked Classe, they said it is no longer available.

Anybody knows a source I could find it?

Thank you!
Alex

i am looking for sonic frontier SFL 2 pre amp DC cable. Grateful if any experts can advise where I can find it. I welcome DIY cable or preloveds.

Sidney2165@yahoo.co.uk

as stated in title, I have 4x2SK1058 genuine pulls from a good FTX2001 channel and I'm looking for 4x2Sj162 to compliment the 1058's I got left. Can be pulls, I don't care what they look like just as long as they work (of course must be genuine). I'm in Canada. Help a brother out man!

A little while back I helped a friend get an old Dual turntable working. He found it at a local Goodwill and thought it would be fun to listen to some old Fred Astaire albums, but was having problems getting it to work. The TT seemed to work OK, it just wasn't outputting any sound. I found several problems with it -- an incorrectly-wired cartridge, the stylus was wrecked, and (most importantly) he had NO phono preamp. I found an inexpensive 5534-based preamp and a replacement stylus and checked the setup out with one of my old Windam Hill sampler albums. Even though the electronics were so-so (and I was listening on so-so headphones), it sounded so good that I decided to revive a lot of my old audio gear. I have an SAE MK3-CM power amp that needed some work and a JFET preamp I designed/built back in the '70s that looked like a good starting point.

Unfortunately, the preamp is dead (and I've lost my schematics for it) so I moved on to the SAE. It hadn't been used since the 80's so I figured the electrolytics were in rough shape. So they got replaced. It was "fun" disassembling the amp, because the previous owner had done some ill-advised mods like soldering all the connectors on the front-end PCB. So as it was, it was impossible to remove the PCBs & replace the electrolytics. I ended up cutting the wires and later devised a replacement connector system with some mini bana plugs/jacks. I also replaced the old RCA phono plugs with gold-plated ones. The old ones were pretty tarnished. I'm fortunate because I also have the original owner's manual AND service manual for it.

I have all the stuff necessary to de-solder parts on PCBs so swapping out the electrolytics wasn't all that difficult. While I was at it, I added 1uf poly caps across all the electrolytics. There was sufficient room to do it, so what the heck.

This last week I reassembled the amp and today I powered it up for the first time in about three decades. Carefully. I have a dual 0-40V lab supply so I could monitor the supply current. Pulled the fuses off one side, powered up the other & vice-versa. No problems, at least nothing obvious. The output voltage offset wasn't all that great, but the amp WAS running at reduced supply voltages. +/-40 vs. the normal +/- 75V. Anyway, after finding no really obvious problems I powered it up with its own power supply and it works just fine. Output offset voltage was in the tens of mV range. The 1KHz sine and square wave looked OK. So far, so good. On the bench w/o a load anyway. That's next.

I also had to use some contact cleaner on the speed-control pots in my Technics SL-120 Mk1 turntable. That seemed to address the speed problem. I have an old Adcom high-output MC cartridge (mounted on an Infinity Black Widow tone arm) that probably will need to be replaced, and designed+built an OPA1656-based preamp to replace my ancient (and dead) preamp. I tested the preamp (and turntable/cartridge) using the audio input on my laptop but eventually want a standalone system.

It will be fun to listen to all my old vinyl again.

Hello everyone,

For a long time I've been planing to build my own speakers and recently I've purchased a pair of Seas Excel W18EX001 woofers at a good price.
Now, I'm looking for a pair of tweeters.

I live in Europe and my budget for the tweeters is in the range of 200-250 euros. I've found a pair of Seas Excel T29AF001 at a very good discount, matching my budget. As I found a model of a DIY speaker kit for this comination of woofer and tweeter, I was convinced that for such a good discount this is the right combination for me.

However, recently I've found a long dicussion on diyAudio from 2018 on a similar topic to this one, which made me change my mind. The main conclusions I've made are:

• for a 2-way sistem with such a woofer I have to choose a tweeter suitable for a very low crossover in the region 1.5kHz (or may be lower).
• a more expensive tweeter (like the T29AF001 in my case) doesn't mean better, for this specific case (as many comments suggested).
• a waveguide (e.g. Monacor WG300) attached to a tweeter would somehow make it easier to apply a low frequency crossover.
• one of the most recommended tweeters for a low requency crossover was SB Acoustics SB26ADC (which fits into my budget). Other models were SB26CDC and SB29RD.

I'm a complete newbie in audio and there are many things I don't understand. However, I'm a physicist and from my general knowledge of spectra the SB26ADC has a much better frequency reponse. The only upside of the T29AF001 is the lower resonance frequency, howver I do not see any related impovemets on the impedance variations in this region.
This said I'm thinking about choosing the SB26ADC tweeter for my project. Still, I do hesitate as the price difference between the tweeters is huge (x4) and there may be other things to take in consideration that I do not know.

If would kindly ask for an optinion, a sugestion or an advice about this problem. It would be much appreciated.

P.S. I plan to build a pair of 2-way compact ported floorstanders with an internal volume of about 30L, made from 25mm (1inch) MDF. The port design and the exact dimensions are not yet calculated. I plan to build a passive crossover with Standard Jantzen Audio or Mundorf EVO components. The exact crossover will be designed after I will install the drivers in the cabinets and measure their frequency reponse. From what I've read on other discussions, I expect to be able to build the crossover with a 2nd order HP filter for tweeter and 4th order LP filter for woofer.

Presently looking at an Arcam Alpha CD player, it wont read or play and seems to struggle spinning the discs. Dropping it into the test mode I was getting error 3 and error 5.

Have already swapped out the 2x Philips axial caps on the mainboard (confirmed bad with tester) but it has made no difference. Have even tried a CDM4/19 laser mechanism out of a Technics player in it and it will not read with this either. Interestingly though when I tried the original CDM4/19 laser assembly out of the Arcam in the technics it won't read discs in there either.

Anyone have any idea on where to check next? Is it possible I have a dead laser unit and a dead motherboard on the Arcam?

Hi,

I'm trying to see if an Icepower 500A module pulled from a subwoofer is working. The original SMPS is definitely not, so I'm testing it using a linear supply from a Pass F3 build at around 53V (without load) and a +/-12V regulated supply built on perfboard using 7812/7912 type regulators. I think I've got everything connected as the datasheet says.

There's no sound, which may mean it's dead of course, but my question is what voltage I should be seeing on the Mute and Standby pins. The datasheet says the board pulls these "high" automatically, but I'm measuring 0.7 and 0.6 volts, which doesn't seem very "high" to me; I would have expected 3.3V or 5V, or something. If these are low then it might mean the board is duff, or maybe needs to be "reset" somehow, perhaps by pulling them high? (Although the datasheet is pretty clear this is meant to be automatically done by the board.)

Any help much appreciated.

Nigel

I am designing a PCB for a tube compressor (Fairchild 670 clone)
The gain reduction "vari mu" circuit employs 16x 6BA6 tubes (8x each channel)

Since it's built on PCBs it would be preferable to power the filaments with DC for best noise performance.
6BA6 filaments are rated 6,3V 300mA so the current requirement sums at 7,7A and this would make for a very large and expensive power transformer.

So I am thinking to power the 6BA6 heaters in a series string.
I have made some calculations and it seems to me the best approach would be making two series strings with a 2x 43V transformer

Voltage drop 8x 6BA6 = 50,4V
Voltage drop current programming resistor = 1,25V
Voltage drop regulator = 10V
Total sum = 60,65V
Power transformer secondary voltage = 43V (60,65V * 0,71)
Power rating = 12,9VA each secondary

I have attached a schematic to show the very simple circuit.

I would mostly appreciate any opinions on this design and whether you have any alternative to suggest.

Hi I have a Northstar DAC that has developed a fault. Does any one know of someone who can test and hopefully fix it? Rgds jotargs

Looking for an i2s over USB v3
Pm please

Hi.I have big 13 inch tower for bass and 4 inch fullrange speakers.I have JLH and F5 amplifiers and like their sounds much but they take too many spaces including Dac.Power cables, Cables for PLLXO and active crossovers, amplifier cables , optical cable, 4 pcs of PTFE Speaker cables there are too many cables and equipment.We are fighting with wife because of these equipment.I like class A sound and i want to build or buy a budget system which includes PLLXO and active crossovers, dac and 4 channel class a amplifiers.Any ideas? If i can build it there will be only one power cable one optical and only 4 speaker cables which i can hide.
I want to build a system as small as possible and use switched mode because otherwise system will be huge.
I searched could not find a proper one. (some of them were very expensive)
Regards

Hi,
I've just bought a pair of speakers on a whim for a project: https://www.aliexpress.com/item/100...llitems_choice_2006574665339.1005005997414703

Yes, it wasn't a very clever idea but it's a done deal. They came with no model number or technical details so they are just like that. A pair of 4ohm 3W speakers.

I'd like to build or more precisely print a pair of enclosure for them. I know there is a tool that is able to measure the necessary values to make the proper calculations for a box but I don't have it.
So, if someone with an extensive knowledge in enclosure building could give me some educated guesses about what sized box would be suitable for this speaker that would be plenty. Preferably I'd like to build a vented box.

Thanks!

Hello everyone,
I try to read everything here on forum, but I would like to start a thread to ask about your opinions.
I already built some speakers with GRS planar and ribbon tweeters, LX521 and recently 3 way with SB26CDC, U22 and dipole bass. Recentrly i bought T34B and I'm planning to try it in 2 way with @augerpro 8" waveguide. I have MiniDSP Flex 8 with Dirac and Hypex NC502MP 8-Channel amplifier.
I would love to try unity/synergy/meh project with dome tweeters, but I don't know if dome will be as good as compression tweeter for this kind of project. I read Synergy Calc V5 and I thought about pairing it with 3FE25 midranges. Also I'm really struggling to understand the difference between EXAR and ATHEX designs (deifference between them). Can anyone help me with this? 🙂
Best,
Max

I picked up an almost trash NAD C372 from the surplus shop and paid 30 bucks on it.
Upon inspection it's powering on but I noticed a smoke came from the Left channel.
Now due to its bad condition, I'm in doubt whether to repair it or use the trafo and heatsinks for DIY amp but I had this wish on my college days to have a NAD amp but no budget that time.
So I started my restoration (maybe the right word on it) removed the defective Left channel and there I found the job that I'm going to do is more than I expected.


Dirt inside and outside.


There are stubborn dirt which are hard to remove so I use water and detergent soap and dry it with high pressure blower (bad idea but I'm doing it most of the time on cleaning some electronics board ensuring to dry it as soon as possible)





The amp module is badly tampered, some parts are not the correct value even the OP's are different.


While I'm on it, I started to replace some "BADCAPS" (why Nad ruin their reputation by using a cheapo caps, to save money maybe🙄).

I don't know if I'm on the right track on doing this. Maybe I'm only wasting my time and money but I want to get it done.
I will post photos of my progress and I hope you share your thoughts and guidance on the Restoration on my Nad C372 😀.

Hi All!

Following the interesting discussion in Sevy's sizzling amplifier thread, which has many frequency plots to determine stability, I decided to use LTspice to look at my own mods on the Maplin amp.

I understand that when the GNFB becomes positive above 0dB gain, it's an oscillator, but just by looking at the output I was way beyond that with lots of gain...
Also then any mods increasing that gain, changes the game, and I think the little capacitors over TR3 and TR4 move the poles (haven't investigated that yet). I think Douglas Self referrs to the one on TR3 as 'Cdom', which I think is the on controlling the dominant pole, or it's just much bigger than the varying transistor parasitic, so it dominates it with a nice external fixed value capacitor.

I wasn't understanding much, as it still had a big gain at 180 degrees... but I know it works well..
... so I then looked at the original amplifier design, as I know that's stable (subject to slight scorching of the output snubber (the emergency brake?) - common on a few of these PCBs...), and found myself asking:

1. What's that bump at 800MHz?
2. Why doesn't this design oscillate?

Eventually I decided to measure the phase margin in a slightly unusual way.. that of each side of the LTP, specifically the bases of each transistor, TR1 and TR2. I figure that this is the actual, important bit, so the phase margin between each side was really the bit that decided it if was an amplifier or a bell, or an oscillator...

Doing this, created the (rather pretty) attached graph, which has a mild phase shift (so it's an amplifier), but I still have this awkward question..
Plotting LPT+ / LTP-, see the red curve, V(ltp_fb) / Vltp_in), well, I've never heard of that, but it seems logical - that's the 'brain', so the question is, 'am I doing it right'?, and 'what else do I need to know'?
This is then allied to the questions of 'should this peak be around 2.2MHz'?

I think that's one of the poles, not sure about zeros. I know what they are but I could learn more 🙂

So could people please have a look and comment? It would be most helpful, thanks!

Need some help
Amplifier goes on protection on the left side only
It is supposed that if any of tubes has a problem then protection flashes tuber red
here this is lot the case
if you swap tubes form the other ch you have the same failure
If you remove tubes totally from the ch still you have this protection issue
Can anyone help ?????

I have noticed that the maudio ultra series have had problems with their preamps. I had an old Omni that had the same issue. I replaced all the capacitors in the preamp but did not solve problem. Does anyone know if the preamp IC is the culprit

For sale is Reference Class AudioPhile preamplifier FlatBT with 2pcb and all values of audiophile Vishay Dale RN60C low noise non induntance metal film resistors, Capacitors is Wuerth Elektronik red edition with low esr and high ripple current. Output transistors are Fairchild KSC and KSA in TO-126 package paired.

Buyer needs to buy heatsink and KSA/KSC in TO-92 case ( mouser have plenty of them at stock).

2pcbs of Shunt PSU called Sipi Shunt PSU high quality shunt psu, so buyer need to buy components. For sale is only 2pcbs.

Schematic will be send to buyer email address.

Price and shipping will be calculated on buyer shipping address information so if you are interest in buying please send private message and your shipping information.

Accepted payment is only by paypal.

Here are pictures of boards and components.

Variously labeled LD-2 / LD-3 FET Input Amplifier. NOT the Burwen modules.
THANKS

I am building bookshelf full-range speakers and I have these beautiful wood sheets that I want to use, however, the sheets are very thin like 6.2mm or 0.24 inches (1/4). Also, I want to use these sheets because I can work very easily with my desktop CNC Snapmaker. The sheets are very solid and stiff. Nothing bendy.

The problem is that I don't know if this will affect the sound and how it would be affected, do you have any idea?

I am not looking for a flat response and I don't mind enclosure resonance, in fact, I like the sound of those speakers with some baffle resonance.

Anyway, how would you say the thickness changes the sound?

Thanks.

Hello friends,

i used the search function, i sailed the whole web, i did my due diligence.

Well, this DAC
https://www.aliexpress.com/item/1005002810554110.html?gatewayAdapt=glo2deu
which seems to be 100% analog to the teradak here
https://home.teradak.com/products/107.html

seems to suffer with a low level hiss (how could i define that? HF intruding anywhere?), which with audio files with low DR (classical music mostly) is really a pain.

My config is an underclocked (though it did not help) rasp 3b+, isolator board OSA electronics (with and without board no difference), the tda1387 dac.
At first I tought it was a faulty item, so i bought it again, the deluxe version this time, to discover the problem is common.
I don't know whether any of you experienced this issue or it is a common problem, it's quite a pity since the sound coming out of this system is very pleasing...

Is there any known diy workaround?

Thank you as always,

Mike

Looking to buy this nakamichi pa7. But the current owner tried to set the bias, and seemingly adjusted resistor VR12L instead of VR11L. It has now blown the fuse and wont start.

I am allowed to bring my multimeter and check it when I pick it up.

Any ideas how I should set the VR12L to avoid blowing the fuse again? Dont think its mentioned in the service manual


Thanks

I have a 1200.1 that has some dc on the outputs cause intermittent distortion on the output

Hi, posting here on the possibility someone can help.

I have a dual mono Buffalo III (ES9018s) stack which was working fine. I tried to upgrade to Trident SRs with SE firmware chip which sent everything crazy, and I've been troubleshooting since.
In summary, channel behavior is now very strange. I checked my system and its fine with other sources so its the twisted pear stack.

Using test tones flac files, I get this behavior:

Test Tone Type....................................Left Speaker....................................Right speaker
-Right channel only...................................silent.............................................test tone
-Left channel only....................................test tone.......................................test tone
-Left + Right channel..............................test tone.........................................silent

So what should play only on the left channel gets played on both channels, and what should play on both channels only plays through the left channel.
Almost as if the left dac (master dac with firmware) is playing stereo and instructing the right dac to play Mono. I think. I'm trying to work out the logic.

Anyone got any ideas about what is happening and any fixes?
regards
Cedric

Hi!

Is there anybody who knows or built the Nishiki amp??
The designer is Wim de Haan and the design was published in the September 2006 issue of AudioXpress.

More infos are in:

http://www.wdehaan.demon.nl/hybrid/nishiki/index.html


Greets:

Tyimo

Hi there. Anyone have any idea where to get this switch from a Cyrus cd 7 it's part 1810 on the optical transport Controll board. Can't find a service manual for this model anywhere!

Thanks in advance

I have been contemplating making my first pair of open baffle 2 way speakers, and have no experience in this endeavor.

So i would appreciate all the help and knowledge you guys are willing to share.
I would like to make something in the look of the pap15. I will be receiving 4 sb audience bianco-15ob350 woofers later today. Bought them firstly due to the fact that they are made for open baffle, and i like the look of the cones. I know that the qts is not higher than the 0.7 mark I have read people mentioning. But coming in at 0.6, with 11.02mm xmax they will do just fine.
At the momment I have a pair of fostex fe126 en lying around, but would like to try sonido sfr200a at a later time.
I have the minidsp shd and 2xclass D power amplifiers.

First question is where do I find the dimensions of the trio 15 baffles? Have looked so many places, and haven't found it yet? Hoping someone maybe has a nice drawing with measurements of the construction.

Can I use the fe126en as a mid/tweeter for the momment or will it be to shouty?

What would be a good crossover point for the sb audience drivers, and fe126?

These are the questions for now.
Regards Mick

hello everybody,
wish you all a happy new year and lots of fun with hi-fi and diy 🙂
has anybody perhaps a spare 1021 board, which he wants to sell? (preferably rev 3 and newer)
mine has hickupps and i think its need replacement ...
thank you!

I have a large number of these hard to find MOSFETs, the 2SJ77 - 2SK214.

For those interested in dimensions, yes, they are laterals.

They originate from a now defunct audio manufacturing company, and were made in -85, as can also be seen in the differing coloring, green and black. Newer ones are all black.

$10/each, $20/pair.

Discounts available on quantities.
Dealer and manufacturers are welcome to enquire.

Ships from Sweden

Thanks for looking.

R

PS: Given that the provenance and numbers are correct, I might be interested in the following Jfets: 2SJ72/2SK147(GR and BL) - 2SJ109/2SK389(BL and V)

Hmmmmmm....
model J2sj109 PJF(Beta=39.21m Rs=0 Rd=0 Betatce=-.5 Lambda=4.338m Vto=-.5762

• Vtotc=-2.5m Cgd=67.64p M=.2562 Pb=.3905 Fc=.5 Cgs=61.12p
• Isr=158.7p Nr=2 Is=15.87p N=1 Xti=3 Alpha=10u Vk=100
• Kf=109.9E-18 Af=1)

I have the pcb's and most parts but open question to all, because a 2SJ109 is basically 2X2SJ74's thermally bonded, has anyone tried them on the input to the Alpha-J?

wouldn't be hard to adapt. I bought a pair of these from Denmark years ago, BL grade. not that they are hard to pull from equipment, lots of amps and preamps use them, like my Acurus RL-ll in the output with their compliment or lots of Classe CA series on the inputs. But I did pay a premium for NOS, BL grade from an estate (I think)

I also have another question, has anyone tried QFets as subs??? I've seen that Mr. Pass has greenlighted FQA25N20 (probably got a letter or number wrong) but how about something a bit more high powered
I have a pile of tru-blu, supply chain verified, FQA46N15's, enough to match them. can I just substitute or maybe complete instability. the rds on values and other features are quite attractive for a design like the Alpha-J

any input is appreciated, I'd like to assemble the pcb's fairly soon and crudely mount to a heatsink, just to experiment. if successful maybe an interesting amp project in progress
these are just questions I have because I'm in a mode where I'm trying to adapt my stock to some cool experiments.

I'm sure many will be able to relate on this forum

shawnra

Hello,

I recently purchased a pair of Speakerlab woofers, the W1208R's. According to Speakerlab at the time, they where the best 12" woofers they built for acoustic suspension systems with great results in subwoofer configurations.

So, that takes me to my reason for this thread. I would love some feedback on what you think I should do with them. I was aiming towards a subwoofer ... maybe along the lines of the "closed-box" acoustic suspension.

Any ideas on a crossover? Firing direction? Any general comments?

I want to do an unpowered subwoofer. I may use it in a home theater environment down the road. I would have a separate amp power it. I have attached the SLab description and specs for review.

Thanks!

Ed

I'm a bit stuck...I guess I'm waiting for some kind of inspiration. I'm torn between doing a sculpted baffle (gloss black) with radius corners, or making the perfect pillar with black laquered wood grain-- the speaker would have square corners and a grill that is flush with the cabinet sides.


Two versions of the scuplted baffle.



What do you think?

Hi everyone, recently I've been updating a little spreadsheet for designing power and output transformers and filter chokes for tube amplifiers.

The early version of this was designed by myself around 2015 and it was mostly based on Patrick Turner design method, but it was far too complicated that Patrick himself didn't like it at all!
so I decided to update it so everyone interested in winding his own transformers can use it.

So here it is; a little spreadsheet for designing power transformer, single ended and push pull output transformers, and also power supply filter chokes.

The spreadsheet is pretty much self explainatory and someone needs only to follow the steps and fill the green cells using cell comments, but if there is any questions I'll be glad to help.

Regards
Sajad

Selling a 500VA Tiger Torroids transformer suitable for any +/-24V Pass style stereo amp.

240/120V primary and 2x 18-0-18 secondaries. This will allow 2-off seperate CRC (or CLC) supplies, each with its own 0-volt reference.

I'll throw in a pair of std rectifiers that I have spare. Traffo is shielded internally - with an earth lead. GOSS banded and black tape wrapped / potted. 138x 60mm

Looking for £50 + £6 for UK postage

I'm confused (not for the first or last time😱 ) about Qtc. Here are two conflicting quotes, but which is correct? Thanks for the help.

From Vandersteen:

" In Subwoofer engineering terms, system Q is the product of a complex mathematical equation derived from driver, electrical and enclosure parameters. In practical terms, it relates to the character of the bass response. A low Q subwoofer sounds highly damped and very tight. A high Q subwoofer produces a warm loose bass with more energy in the most audible bass range. The trick has always been to try to find the subwoofer with the Q that best matched your listening room and personal tastes.

The 2Wq is the first subwoofer to feature adjustable Q.A bass contour control on the rear panel allows you to set the system Q anywhere from ..5 (Slightly overdamped, i.e.., tight jazz sound) to 1.2 (Significantly underdamped, i.e.., typical mass-market home theater sound)."

From GRollins:

"A point that tends to get lost in the shuffle is the Q of the (sub)woofer. Critically damped (i.e. .707) is a maximally flat Butterworth alignment. Bessel will give you .5, etc. The thing is that some people go for a .5 alignment because it 'gives you more bass.' Hmmm...well, yes...and no. It rolls off more slowly, but begins rolling off sooner (i.e. higher up). A properly designed .707 cabinet will roll off with a sharper slope (which some chose to interpret as 'less bass') but stays within a tighter range in the pass band and the rolloff begins at a lower frequency. Your choice. But there's a catch. Going for a Q of .5 to get 'more bass' means a compromise--the bass you get is less tight. You want really tight bass? Try a Q of 1 or more . Of course, now you've got a pronounced hump just before rolloff, but hey, you wanted tight bass.
The stereo gods giveth and the stereo gods taketh away."

Reaching out to a kind DIYA-member, who could help me buying one of these:

https://www.ebay.co.uk/itm/284696162283

and forward it in a small bubble envelope to Denmark. Obviously seller doesn´t ship outside Germany.
I sent him a message through Ebay, but no answer.
I´ll pay all costs by PayPal (family and friends) to anyone (preferably German), who could help me out here.
It´s an idler belt for a Kenwood KX-800 (no extra suffix), which has exeptional sentimental value to a friend of mine, and I
promised to fix it. Haven´t seen this belt for sale anywhere else, so please...... anyone??
Just PM me with details, and I´ll write back whith shipping adress etc.

Hi everyone, first time poster long time reader!

For a long time I've wound many output transformers for guitar amps and due to Low-Fi nature of guitar amps OPTs turnrd out to be good enough, but this time I'm in process of winding my first Hi-Fi tube amp output transformer, and after gathering information from several sources like RDH4, Wolpert's books and mostly important Patrick Turner's website, I realized that I need to find a good GOSS material for this purpose;

After alot of searching for available core materials I could only find some Non-grain oriented silicon steel (NOSS) material from china that nearly there is no data on this material anywhere! The seller only knows that it is M470 NOSS material and he's not even sure about it!!
With this material I know my OPTs will weight like a battleship but I don't have any other option right now.

So I'm wondering if there is any method that I can use to measure permeability vs flux density of an unknown core lamination using maybe an oscilloscope and a test winding with known turns??

Any help would be greatly appreciated!

Sajad

Hi, I'm new to the forum and am just getting up to speed with a newly acquired Quad 306.

It's slightly wonky with some 50Hz noise on the right channel, plus a few volts DC off set on the RH output with no signal input.

Having read some of the existing 306 threads .... My question is, can anyone point me in the direction of SIM files (*.asc) for use in LT Spice?

Plan is to take some voltage readings and pinpoint where the DC offset is coming from (am a sparky by trade, but am new to electronics).

Many thanks
🙂

Hi,

I currently have 3-way sealed enclosures with a single WO24P-8. Active crossover by using a Hypex FA123. Crossed over at 450hz or so. Box calculated qtc around 0.7. Before this I tried a ported design but I like the sound of the WO24P-8 sealed much better.

Because of unrelated reasons, I'm making new enclosures. I'm thinking about doubling up on my woofers, two WO24P-8 per tower. But really, is there any use? I listen at low volume levels. With the Hypex I can EQ the bottom end of the single woofer so that it plays as low as it needs to. Double woofers would increase the sensitivity of the woofer ensemble, so I can remove the negative gain on mid and tweeter. Doesn't seem important in my situation with active crossover.

Only think I can think of is that the floor bounce of the two woofers is at different frequencies, perhaps creating a more even in-room response. Is that alone worth it?

Am I missing something, or is a second woofer a silly idea in this case. It would also make my enclosures a lot larger.

Thanks
Vincent

Have build a 91 liter netto box for my Dayton RSS390ho.
The cut out is cc 23 cm from box-ending on one side, and cc 43 cm from box-ending on the other side.
I want to mount 4 legs 25 mm in hight, but don´t drill at the "wrong side" in my Walnut imitation. (which I worked with for 3 days)

Is the lower montage "better" for "bass-support" regarding "floor-helping"?
It´s a 15 inch sidemounted xcrossed at 150 hz, and 2400 hz and going to be used as a 3 way.

Then speaker placement in stereo, play inwards towards each other or outwards in each direction?

Best regards John

Hi ! Here is a nap300 build I just completed for a friend. He gave me acces to a few pairs of original nap250 boards and asked me to build him an amp around the only pair of nap300 boards he had. Given the price of these amps on the new market, I couldn’t say no. (Free projects, why would I say no anyway) it has two 500va transformers that were made for Cambridge 650r receicers and a total of 80000uf. anyway, that is the story behind the build. I still have two other build to complete with nap250 boards.

So here is my question. I don’t have access to the service manual or even a schematic for the nap300. I have set the bias to 9mv across both 22r emiter resistors according to the information i’ve found on the internet. DC offset is damn near perfect at 1mV on both channels. BUT, there’s two more pots on each boards that are still unused (by me). My guess is that they are used to set the rail’s voltage, but I don’t know what voltage to set it and where to measure it. Does anyone have information about this ? Thanks !

btw, it sounds incredible. Very detailed but smooth at the same time. Really good match with my series 80 B&W 802 ! The clear cover is only temporary…

I've got a skar rp20001d and I and new at trying to fix them and would love some help

Hi everyone, I'm new to DAC and would like to try different DAC available in the market. Recently I purchased the ProtoDAC, which works directly with Raspberry Pi through the I2S interface, and everything works like a charm.

The ProtoDAC comes with a DAC module, which is basically 8x TDA1387 in parallel. Having checked the datasheet of TDA1387 and TDA1543, both of them use the I2S protocol. Therefore, I replaced the TDA1387 module with the TDA1543 IC by mapping the I2S (WS, DATA & BCK), VDD and GND pins. Unfortunately, I could not get pure music but a mix of music and noise.

What I can confirm:

• TDA1543 is working fine (will explain below)
• It is the TDA1543, not the TDA1543A
• TDA1543 works with CS8412 I2S output mode
• the resistor in the passive I/V stage is changed to 1K because of the smaller output current
• VDD and GND are connected

Symptoms observed:

• Volume control seems not working (no problem with TDA1387)
• Output is a mix of music and noise

At first I thought the TDA1543 was faulty, then I purchased a couple of them from different vendors but all of them exhibited the same behavior, Then I purchased a finished kit which converts SPDIF signal to I2S, and all TDA1543 worked fine.

The converter KIT has a CS8412 which converts SPDIF signals to I2S signals. Again, having checked the Datasheet of CS8412, I confirmed that the output was configured as I2S mode.
M3=0
M2=0
M1=1
M0=0

So I started to think about the driver issue from Raspberry Pi. Here is the connection between TDA1543 and Pi 4:

TDA1543 <-> Pi4 (GPIO)
BCK (Pin1) <-> BCK (Pin12)
WS (Pin2) <-> LRCK (Pin35)
DATA (Pin3) <-> DOUT (Pin 40)
GND (Pin4) <-> GND (Pin 6)
VDD (Pin5) <-> 5V (Pin2)

Attachment is the converter kit and it works flawlessly when fed with SPDIF signal. Could anyone point me to the right direction? I feel frustrated. Thank you.

P.S. Before asking for help, I also Googled and seemed older version of Pi worked with TDA1543 without any issues. I just tried many ways but could not fix the problem.

So for the KEF Uni Q project……..first and at first glance easiest option would be the large 11” Blanca bowls from Ikea….each enclosure comprised of two halves clam shelled. Not expensive and bracing easily added to compensate for the somewhat thin Bamboo construction.
…..but then I see the stainless bowls……available in 11” and 8”…….one of each would be perfect for epoxy casting half hemispheres. I could even do a carbon fiber layup on the 8” outside and then cast it into the 11”……..a 3/4 thick clear cast layer over CF?… might be something to look at, no?

If my math is correct, each half sphere would be 3/4” thick and take just under 1 gallon of resin to cast……not exactly cheap but under $300 for two 11” full spheres all in with the Ikea stainless bowls as molds and some carbon fiber for the inside layup.

I could join each half together with a circle cut and chamfered piece of MDF……a few mills less than the cast circumference and maybe wrap that with a nice piece of brushed aluminum?……..

These would be heavy though…..certainly as non resonant as could be.

If anyone has any other suggestions for a different casting material….feel free to make suggestions. Would some kind of acrylic fortified cement/plaster or such work too?……it would have to be thin enough to cast into half spheres without significant voids though…..filling, sanding and painting would not offset the cost savings over the epoxy. Nice thing about the metal ikea bowls is I can heat them from the outside to be sure to release all of the trapped air.

Hi, my pa system is power amp, mixer and 2 EV 12" speakers

I'm asking if the power amp should be turned up full and then let the mixer control the volume.
Thank you

Steve G

I'd like a little midrange module for my spare B&C 8PL21 - simple to make from half-inch plywood and xover ~350Hz on the low end.

The owner of the local electronics supply shop (Norvac) contacted me a couple of days ago as I had asked him to order me 4 cans of Caig F5, which by the way they went back to their old spray top, woohoo! He is constantly giving me parts I need for free and when I need things like this pot cleaner I like to give him the business.

When I went to pick them up, he asked if we could work out some type of deal. His brother has a Marantz 2220 that completely stopped working in one channel and he asked if I could fix it and exchange for the cleaner, plus he gave me some other things. I told him I would fix it, but I would also go ahead and do a bit of a restoration since it’s his brothers. so I’ve been through the entire amp, it got a full recap, new Zeners, some new transistors to replace the ones known to go faulty, etc.

Onto the driver board that’s when I saw it had a catastrophic failure. An electrolytic had completely exploded, there were multiple resistors that had burnt and gone open, the two outputs on that channel were shorted, and there are a couple of transistors that had gotten very hot and exploded themselves, also both emitter resistors are open.





I have already replaced all of the capacitors and all of the burnt resistors. I still need to go through the rest of the board board, I’m going to check every piece of silicon there is including the germanium diodes, 1N60s. The two transistors in red are the physically damaged.



I do know that the drivers are toast, they were originally 2SC1509 and 2SA777. I could either go KSC2383/KSA1013 or go a little overkill with TTC004b/TTA004b. Not sure with the original Ft being 60 MHz it being better to step down to 20 MHz or up to 100 MHz. I’m thinking the Toshiba devices would be the better way to go.





That isn’t too much of an issue, the one I’m having the most trouble deciding on is H704 which is a 2SC1175…

Dan

Greetings all,

I came to a possession of a turntable with the above-identified cartridge. When looking for the technology (MM or MC), it seems to be neither, is is described as a "moving magnetic cross" or a "moving iron cartridge" whatever does that mean.

The question is, what phono-preamplifier do I need? Any DIY recommendation?

Kindest regards,

M

Hello,


I would like to introduce you to my DIY amplifier. It works with the probably best known transistor, the 2N3055.

Some years ago I was looking for a simple circuit for the 2N3055 and bought a module from China. I built it, but the result was not very good. During my search on the internet I came across El Cheapo.

https://pe2bz.philpem.me.uk/Mi...t-El-Cheapo/project12.htm

https://sound-au.com/project12a.htm

I adjusted the circuit a bit and added a simple but well working quiescent current control. The result is this schematic.



I converted the module from China to this schematic and then installed it in an old Dual case, which I rebuilt.
The result sounds really good. The amp has a warm sound, yet has very fine resolution and imaging. It is supposed to go in the direction of the Quad 303. I have not heard a Quad 303 yet. Since the circuit is similar in basic principle, I can certainly imagine it.

I have already presented El Cheapo in several videos. Who would like to occupy himself with it finds here further info.

Login to view embedded media Login to view embedded media Login to view embedded media

Finally, a few months ago, as part of a community project of the german www.Dual-Board.de and the www.analog-forum.de, a PCB-board was created on which you can build an El Cheapo. I wrote the assembly instructions, but they are only available in German.





In the meantime there are already three finished replicas. The feedbacks are all positive, the sound seems to convince.







I am currently building a special version, the "El Cheapo compact". I replaced the 2N3055 and the two BD139/140 by two complimentary Darlingstons (MJ901/1001). Thus one can reduce the space requirement strongly. In the driver stage there is no BD140 but a germanium transistor. This makes the sound a bit softer, more tube-like. By the way, the schematic is not completely dissimilar to the "Black Devil" amplifier. However, I use a different quiescent current control.

Finally, the circuit of EL Cheapo and also now EL Cheapo is very variable. You can use many different transistors, adjust the values of the capacitors and electrolytic capacitors, make other modifications. So you can adjust the sound.

I would be happy to start a small discussion here.

Many greetings

Frank
My Youtube-Channel: https://www.youtube.com/@lowpoweramps

Peavey, EV, Sunn (I think) all had these type with throat area ~= or >Sd, and horn depth only a few inches.

A friend who built the one below with PRV 10", compared it to a simple box.- Female listeners preferred the vocal projector to the plain sealed box.

Under what circumstances is this technique useful?

I'm looking for all the Audio Amateur issues from 1988

Recently I tested my Buffalo II DAC from Twistedpear - a 1kHz sine 0dB Test Tone.
There is a "squarelike" but faint distortion in the upper frequencies.
But before running a verdict, I should mention that the testtone is from 1982,
from an YEDS-18 Test disc made by Sony for service personnel.
I analysed the file in Audacity , one sample width shows clipping,
whereas 3 samples show no clipping.
No clue what the sample width practically means.
Assuming the sample is error free and spot on with full scale,
clipping needs at least two samples, because the resulting curve
between the two samples overshoots 0dB.
But the test tone on the YEDS 18 it was made while only 16bit ladder resistor DACs
were common, to my knowledge, clipping with them is more audible.
I analysed the file in Audacity , one sample width shows clipping,
whereas 3 samples show no clipping.

The 60 second sine testtone from the YEDS-18 is too big to be attached.
So here is a downloadlink from Wetransfer, it is valid for 7 days:

WeTransfer

Would be interesting to hear whether the fault is a test-signal from the dawn
of the Digital Age, or DACs that spoil a signal with no headroom while upsampling...

EDIT: Audacity also has a tone generator. The generated sinetone made by Audacity also "clips"
when being analysed with one sample of distance.
So this analyse tool seems to be useless or a 1KHz Tone at full scale clips by default,
as there are overshoots between samples...?

Working on rebuilding an 800.2 completely. I’m stuck on the drive circuit. I have no output to the gate pins. I’ve replaced TL494C with a new one also replaced all four smt 2A / 1A. There’s no voltage present at the gates.

https://www.hificollective.co.uk/sites/default/files/mdt-33-datasheet.pdf

Morel MDT33 -legend MADE IN ENGLAND
condition close to new
i have 2 pair this one used once for test
sound very close to beryllium tweeter sound
clear and crisp

box and all pack original condition

400$US pair



These tweeters represent the finest in soft dome tweeter construction. Features a treated 1-1/8" soft dome, ferro fluid cooled aluminum voice coil, and double magnet system that is vented into a damped rear chamber for exceptional power handling and exceedingly low distortion.

Specification:

Znom 8 ohm
Re 5.2 ohm
Le@1kHz 0.09 mH
VC height: 2,7mm
Air gap height height: 2,5mm
Lineal coil travel: 0.2mm
fs 700 Hz
Mms 0.44 g
Sd 6.0 cm2
BL 6.3 N/A
VC Ø 28 mm
Sensitivity 1W / 1m 92.5 dB
Nom. power DIN 200 W
Weight 1.1 kg

pair SEAS Excel W26FX-001 (E0026-08S) 10" Aluminum Alloy Cone Woofer
price for 1 pair

Product Specifications
Manufacturer SEAS EXCEL
Speaker Type Aluminium Magnesium Cone Woofer
Nominal Diameter 27cm
Impedance 8 ohms
Power Handling (RMS) 150 W
Frequency Response 20 - 1000 Hz
Sensitivity 87 dB
Voice Coil Diameter 51mm

720$ US+ shipping + paypal fees
all in original packaging

For sail AUDIO TECHNOLOGY 18H521506SD midwoofer
Price for pair 475$+ shipping

Resonance frequency - fs:
40 Hz
Equivalent volume - Vas:
28,5 liter


Qms
1,8
Qes
0,39
Qts
0,32


Nominal impedance - Zn
8 ohm
DC resistance - re:
5,6 Ohm


Effective cone area - Sd:
137 cm2
Compliance – Cms:
1,09 mm/N
Mechanical resistance – Rms:
2,04 kg/s
Moving mass – mms:
14,6 g
Inductance 1 KHz – Le:
0,13mH
Force factor – Bl:
7,3 N/A


Winding height – Hc:
17 mm
Air gap height – Hg:
6 mm
Nominal power – Pn:
150 W


Acceleration factor:
499
Efficiency – SPL:
89 dB

Got this amp with blown power supply fets and driver transistors. Fets were IRFP064N. This amp was repaired earlier and technician had spoiled someone the vias of power supply driver board. I changed fets to 75344g and also gate resistors 51.1ohms. Amp coming on and producing good clean outputs. But power fets gets very hot at idle. And almost pulling 2.1amps. Any suggestions?

Hi diy audio form,

Im imagining to build a subwoofer couch- a couch that can observe normal couch functions, but also be a capable deep reaching subwoofer when i need to throw big party in my house or to suprise people.
background:

• Ive built sealed and ported boxes before, 18 and 15 inch woofers for permanent pa system, designed coverage for specific rooms. but i want to go wilder-
• i have access to a cnc machine, and lots of cheap good MDF. subwoofer design dream, i know-
• I dont have a problem with a complex internal structure of the couch / bracing. I can build box.
• I dont give a thought about size or weight. this thing could be 600lbs.
• I'm not religious, I dont give thought about adhere to audio dogma. I want this design to be unorthodox, I don't care if it's not perfect. I want it to be loud, still good sounding, and be an interesting talking point for guests as well as able to run the dance floor.

So, my idea is that I don't want the woofers visible, both to protect them from damage and I don't like the look of metal mesh / grates over the drivers. just a personal issue sorry. I already have an 18 inch eminence impero i want to use for this, and then I want to get a 21" as ive never used one before. The idea I have is to have the couch split into two separate subs internally, intimately crossed together. I'm thinking the 21" to cover 18hz to 40 or so, and then the 18" section to cover 40 to 90 or higher. Since the subs are enclosed in the couch, and these are such narrow bands that I only need, want to take advantage of the situation and do them 4th order or 6th order bandpass to make it earthshaking. I'm thinking the space under the arm rests could be big vertial ports on each side, the left side for the 21" and the right side for the 18". What if this could also create some interesting phantom stereo bass action with the different frequencies coming from each port. Again, don't care about perfection. Want interesting.

SO, just putting this here to get people thoughts on this, 4th order or 6th order, or other configs for the two woofers in the couch. Anything you want to say. Love speaker building 😛

Got a Revox B790, no power when plug in. Power board had a Cap that was shorted and broken power switch. Repaired power switch, Rebuilt power board( caps, thermistors, bridge rectifiers, and regulators), recapped all electrolytics on other boards. TT now turns on, digital LEDs light, motor spins, arm moves, cartridge raises and lowers. Voltage from Power board appear in spec. Great, but here are the problems:
1. When first turn on, motor turns on briefly then stops, even before the tracking arm is moved into position
2. The LED display turns off when arm is moved into tracking position.thus no reading of rpm is possible
3. the motor has a clicking sound ( when motor is manually spun (not turn on) no clicking/ noise noted

I really like the quality of the stores "blue" circuit boards, eg. The Universal Power Supply board. Can someone tell me who the manufacturer is and what thickness the copper is? Those boards withstand repeated soldering/desoldering really well. Thanks in advance.

Please help. I have a MRX-130. It worked on the AUX, and Phone settings. LEDs on the buttons lit up. FM and AM did not work, no sound at all, the Display showed zero. I purchased kits from Les (Circuitsandconcepts) and installed new caps on the main board, Les' regulator, and a new Trip Cap in the sandwich stack for the display. I installed all and triple checked the solder for errors. When I powered it up with input to the AUX it sounded great and the power on light at the bottom of the display lite up. However, now I had no display at all and the selection button leds are not lite. I can not change to any other inputs. I have triple checked all solder, I have checked with my in-circuit tester all caps. I went to "thecarversite" and have not found anything that can help me. I checked a few voltages:

On the Preamp, TC9152
Pin 24: +14.7V
Pin 12 : – 15.0V
On the tuner TC9147 pins.
Pin 42 and 41: 5v
Pin 34 and 35: 1.802V

I do not want to trash bin this receiver. I restored one a year ago and it was really nice. Any suggestions would be greatly appreciated.

Hello
This is my fist time doing a post so hope i am doing correctly and in the correct place. See correspondence from a Teck. i have used for years that is suggesting i get someone with experience with these amps to look at it .He did the usual things that old amps. need but then ran into this issue below .My problem is that Georgetown [ if one was interested in looking at it ] is along way from Ottawa and this amp. is heavy to ship.
Any suggestions
Cheers

"Hi David,

Further research on possible causes of the observed power supply issues suggested that the transistor Q1 (MPSA93) might be faulty (it is close to the part of the board which had the overheating resistors). However, replacing the MPSA93 did not solve the intermittent power supply issues.

The Carver M1.5 does not use a typical linear power supply; it has a "tracking" power supply that varies the B+ and B- rails to follow the input music signal. Although reputed to be an excellent design, troubleshooting faults is a complicated process (see pages 18-21 of the attached service manual). The problem may very well be with the leaky/failing dual capacitors (C13/C14) that I mentioned in my earlier message. And as discussed in the linked AK thread in the earlier message as well as the M1.5 Service Bulletin (included in Service Manual), their replacement requires an adapter board since dual can capacitors are no longer available. I do not know of any local source for the adapter board, but it is available from after-market sellers on eBay, e.g., https://www.ebay.com/itm/220766804156?hash=item3366ba18bc:g:GjcAAOSwUuFWxmds.

At this point, I think it would be best to have your unit looked at by a tech that is familiar with Carver amplifiers rather than me since I lack specific knowledge/experience with this type of design. I know of a former Carver Authorized Service Centre/Distributor with an excellent reputation that might be able to help; he is an Administrator at DIYAudio (https://www.diyaudio.com/community/members/anatech.12165/ ) and is located in Georgetown, ON."

Good morning,

For sale this Swiss tool 🙂 Phono, ADC, setup tool.....very handy.
From September 23
Updated
Paid 548$+VAT+CUSTOM....
Barely used,
SOLD
https://parksaudiollc.com/

Hi everyone. Im new here
I need a little help
Me and my father built a Pass Labs aleph 3 amp and the problem is that when we turn the volume up on the preamp, at the bass it distors a bit.
The question is what can we do with it
I atached some pictures of the amp if the problem is with the cables

Hello all, I haven't been here in awhile so sorry if this topic may have been talked about before.

I'm currently planning to a Jim Griffin's Line Array using the Dayton Audio DMA105-8 4" driver. I will be doing a Power Taper using his guide on the white paper to get 8 Ohms or slightly over. Now my question is even though these are Full Range speakers with 70Hz- 20Khz range, can I get away without a Crossover? I do have 2 Monolith THX 10" 500W subs to use in cause it does need lower end help.

I will be doing a 12 driver per side build. hopefully I will not need too much help in that part. I do have Xover Pro software to help if i do need a Xover to help this build.

Anything else I may need that I may be missing?

Hello,
I bought a bluetooth module based on QCC3034 chip bt module and I want to program it but I don't know the pinout of this board. Anyone can help?
Thanks!

I am currently measuring my subwoofer with dayton audio umm 6 mic. But in REW its doesn't show any low frequency spl & it show good spl from 150hz..
I m not getting wether it a fault of mic or software..
If any buddy know something about this please let me know.

Hi guys,

As you know, a lot of vintage woofers have paper surrounds, that get fragile or may have already started showing splits.

How do you revive or reinforce or make these compliant?

What do you use and how do you do it?

In good condition, with some mounting marks. Function perfectly, can provide impedance sweep data on request

325USD/300EUR/500AU for the pair + shipping. If interested let me know and I will enquire for shipping to your area. Cheer

.

Hi everyone, please help me with finding the schematics or the service manual for Cambridge Azur 840E preamp. Unfortunately, my beloved Cambridge Audio 840E preamp is broken.

Thank you in advance.

sanji99

I recently dug out my long forgotten sub I put up together sometime ago, so I decided to pair it up with my DIY bookshelf speakers based on w12cy001 + XT25 to see how this setup would work. Amazingly, it got me exactly where I wanted - very close, if not over the KEF Reference 3 overall. It's a 28l closed box with JBL CS1210 car woofer that I found on sale for 40eur. Now that I got my appetite for low end in the open, I'd like to see if I could upgrade it to something even better. I can't see what the Fs is for this woofer, but probably not too stellar. I do run it with FreeDSP into Sure Electronics 200W class D mono block so I can adjust and flat it out pretty well, but there are probably still limits on how low it could go. Would a switch to GRS 12SW-HE with Fs of 22Hz make any sense? I wouldn't mind going even for something substantially more expensive if that would make audible improvement, considering I am listening mostly at lower levels.

Putting this together now, but not open baffle due to aesthetics.
I can still change it at this point:

Will it sound like ****?​

Also when it's open baffle it's radiating surface is 104 cm^2 instead of 52 cm^2.
This GRS sounded fine open baffle crossed at 300 Hz on my table.
The Dayton RS52AN did not sound as good, especially in the low end, which was surprising to me.

Why does Zaph write this about the B&G neo3 :
"Note: these were tested with the rear chamber in place. Later, with a different pair, I also tested with the chamber removed. The tweeter was far too overdamped in that case, and I recommend leaving the rear chamber installed."
Why is overdamped bad?
Is GRS like this?
Marketing claims GRS PT6816-8 is for "open-baffle" "line array".

My enclosure is almost done.

SB Acoustics SB23CACS45-4 8" ceramic woofer- 4 ohms is also a great woofer​

SB is more for bass and build quality is really nice.
If you want 20 Hz to 1 KHz, it seems to be a good choice.
Seas has more detail and my metal grill fits over it.

I am looking for an ACA mini that works perfectly.
THANKS

HI,
I bought a drawing of a Yuichi A-290 horn.
I know that the best solution would be to mill it in wood with a CNC, but the cost is very high..
I tried 3D printing them and they don't look bad, but I'm not sure I set good printing parameters.
Can good results be achieved with 3D printing?
I was thinking of trying to print them again, empty inside, with 10 wall shells, and then pouring some plaster inside...
could this be a good idea?
the drivers are jbl 375 and the printer is a bambulab
Thanks and sorry for my English..

Discipline by King Crimson.. 40th anniversary cd set. Finely crafted music by very talented musicians.
https://www.amazon.com/dp/B005FMB8X6?psc=1&ref=ppx_yo2ov_dt_b_product_details
Interesting that as far as I can tell there are no synthesizers used by the musicians. Whether or not they were used during mastering is not known to me.