high voltage tubes with 12V or 5V heater

Hi,

I'm working on a project with high voltage tubes like the 6HS5 family - min. 5000V max Va, > 20W Pa, >100mA Ia. The 6HS5 fits the bill but to design constraints I would want such a tube with 12V (12.6V) or 5V heater instead of 6.3V.

Anyone knows of such an animal?

Jan

if you set a digital scope to a low setting, say 2mV/div and the short the probe tip to its ground lead, what sort of trace is typically seen? would you get a thin line as per analog scope or will it be a fatter trace?

It turns out that Mouser and Digikey don't have anything in 34-35mm diameter that fit the requirements for 80 VDC and 22K uF.

The caps I need to replace are 34x80mm and 34x100mm. 15K uf and 22K uF both at 80V.

Closest I can source at Mouser is 40mm diameter, which will bump into the bus bars on the PCB and will prevent fitting the plastic cover over the far end of the cap bodies, which secures it from vibration, to chassis.

I found some similar caps in screw terminal, but these are four terminal snap ins that solder directly to the PCB. Originals are NAD-branded.

Who sells these?

**We're on round #7!!!**

I've confirmed how to order parts, made sure it isn't an issue for Comocos. (please no more requesting samples)

So over the years people have asked about the old version, made by someone else.

It's probably time for an updated one. This one is a bit different. You may notice it does not have following capacitors after the choke. I have tried both ways, and my preference is strongly without the following X2 capacitors. Also the capacitors prior to the choke are not varied in size because overall capacitance is more important - and they won't randomly resonate with each other.

The other major change is the addition of bypass resistors for the chokes. These don't ruin the filtration, but they do a good job of quieting the chokes that can get excited by different combinations of things on the mains.

Click to expand...

Gen1 w/comoco's


Here's how it is different in settling time from the original.


Here's a comparison between resonances.

*2oz copper PCB (1oz is standard)
*Weco 983ZD terminals, copper alloy and can accept 2 wires for daisy chain. These are also safer, particularly if you use solid core wire that otherwise likes to make cold solder joints you can't see.
*X2 rated capacitors for safety, 4x 0.47uf. They are alternated for CFC (capacitor field cancellation).
*Discharge resistor for X2 capacitors
*Coilcraft Comoco choke w/fuse or Bourns 8120/8121-RC choke w/o fuse & 15/16A/20A(*) max sockets
*Fuse clips are beryllium copper (good for 30A)
*120/230v operation (parts & pcb)
*Mounting holes are sized to work nicely with M3 screws and standoff kits
*Size: 2.25x4.25in

Click to expand...

The Weco 983ZD are preferred terminals, but not always available as individual sale. For this reason I'm going to include them in the price of PCB, so that I can meet min order requirements for them and save everyone the shipping.

Price: $13ea ($9 per filter board same as original, $2 per Weco, 2 needed per board)

Shipping: $9 US, priority USPS box
$16 CAD
$17 General international padded envelope (prices may vary due to a crazy world)

If ordering over 4x boards there may be an additional $10, depending on destination.

Need 32 filter board commitments to order.

lordvader 3
Knuds1 4
docjrev 6
Dadbeh 2
gary s 3
wirewiggler 3
JRKO 4
DaveM 4
rtate 3
mrloud 3
loWfi4evR 2
ccliu 2
sampsonite 6
pwagner 4
chiily 3
webber 4
skunark 4
turion64 3
32y0 4
jam econo 4
pistollero 4
jack_b 4
ericimage2 5
Chilkoot 4
dualuxe 1

Click to expand...

I have an amp with single speaker terminals, I would like to add two more terminals as I have tri-wire speakers and a sub that connects via speaker level inputs.

Planning to make a copper plate that I can attach like a spade with two holes on the side to to connect two additional terminals. The existing terminal has enough clearance to prevent the new terminals from hitting the back cover.

My question are.
1. Is copper the best material for the plate?
2. Do i need to have the copper plated?
2. How thick would the plate need to be ?

I am nearing completion of building a FHXL. I have no idea what the horn is, or why this has its particular design. It would appear that the driver is placed so that half of the sound "goes" over the top into a wedge shape that dead ends. What is the purpose of that wedge? What do the slopes sides do, and why are they critical? What dimensions are cricical? What is the purpose of the fill, and how does fill "work"? If anyone can provide me with a basic understanding I would appreciate understanding the "why" behind the design.

Thanks

Hello!

I plan to build a 3-Way Open Baffle and want to get the best out of it. The goal is to make compromises that do not limit the sound quality to much.

My wishlist 😀

- Overall good dispersion (horizontally and vertically [WMTMW?]) with a smooth target curve (see Toole)
- Transient XO passiv
- Flat response
- Enough low distortion

I dont hear loud music (never more then 90db), because of my neighborhood.


General Problems with 3-Way OB are that one driver can only play for 2-3 Octave. My solution so far:

Bass- Low Mids:
Some years ago i have seen a speaker that goes incredible low in an open baffle because of a stimulated movement of the complete baffle (there was made some acceleration measurements). Click here...
For my bass section and the low mids i will use 2 or 3 of the Monacor SP-225 per side. (Probably i have to make some test with different baffle-sizes)

I think i could use the SP-255 in this way from 20Hz to maximum 600Hz!



Tweeter:

I think the best solution we can see with the BG NEO 3 (vertical position) on the Aino Gradient Speaker.
Alternative....
.... Radian LT2, Dayton PTMini 6 (They aren't able to crossover so low like Neo3 and if crossed higher its harder to get a smooth vertical dispersion)

..... Peerless OC16SC04 (Higher crossover-frequency and most worse dispersion of all alternatives because of big dipol-width at 7-8khz)

..... Peerless TC5FC02 (At Cone Breakup probably loose of a good dispersion on the baackside of the driver at 5 khz. Compared to this the Neo3 will hold up till 7 khz)

Therefore i think the best selection is the Neo3 (additionaly it has a good reputation) and when we need a better distortion because of a low crossover point probably the TC5FC02 could be a second option!


THE MOST DIFFICULT PART - WHAT COMPROMISES TO DO?
Filler (600Hz-2,4khz):

If we go to ask for the best dispersion, we take 4 of the Filler in a
W
MM
T
MM
W
configuratioin. The best 1,5" i have found:
1,5" Peerless by Tymphany TC5FC07-04
Alternativly Dayton Audio DMA45-4 but not loud enough.

Or only two of Tang Band W23-1287SI

As Info for the Peerless driver, the 'd'Appolito crossover-frequency would be 570Hz and 2,2khz. With these little drivers i can simulate a very nice vertical and horizontal dispersion.

Or is distortion and dynamic that bad, that we should go for something bigger?
Other Ideas?


Best regards, Tomas

For sale full set of drivers purchased for Linkwitz Orion speakers that were used only one time, then disassembled and put in box (were my dad’s, who passed away :-( ). Practically brand new except one tweeter does need new voice coil.

$1900 OBO takes all

Can ship or local pickup also OK (I am located in Rhode Island)

Thanks

Hi everyone,

I have 9 B52 Matrix 2000 systems, where I daisy chain them all to make this huge sub wall. Its about time to service them and I was under the impression that I could get more out of these by upgrading the driver. Someone recommended the Faitel Pro HP1010, or 18 sound 18’s because they can handle what the amp is feeding.

Currently the amp I believe provides 600w to the sub channel and 600 is spilt between the 12” highs. So my question is Is there a driver I can put in this box that will hit more powerfully, efficiently (less heat, friction), and lower than what is in these now? I think some of these are loaded with FSW or FTW eminece’s, rebadged.

Or can you recommend a new system that will crush this setup, (everybody always screams bassboss😀) That I can use 3 20a circuits.

Thank you so much!!

I just built a Soekris dam 1021 R-2R DAC.
But how do I found out wich COM port it is connected,I have at least 6-8 USB ports.Is there a commant in windows I can se that???

I recently took apart a Celestion CS135. After reading a review I was expecting a decent crossover but I was misinformed.

How does the lack of a proper crossover affect overall impedance?

Hi all,
I've been thinking about doing my first small-medium subwoofer build and I'm hoping someone would be kind and patient enough to critique what I've come up with so far. This is a bit long winded as I'm trying to talk my way to a decision.

My project goal is for a -3dB in the mid-30s, with an overall volume less than 2cf. Maximum SPL isn't a priority. I already own a Dayton 100W plate amp that I'll start the project off with, but probably upgrade in the future. I have a budget of $200 or so for drivers/ports/etc, and I'm in Canada so driver selection tends to be a little more limited but Solen.ca is usually my go-to. I mostly played around with the Dayton Audio DCS255, DCS305, RSS(210/265/315)HF, and MX10.

I've already crossed sealed boxes off my list as I know I can't meet my goals without a massive box and/or DSP which I don't have the ability to do right now.

Finalist 1
Driver : Dayton DCS255-4
Box : 1.8cf, tuned to 32 Hz
Port : 4" x 16" round
Total Volume : 2.3 cf (includes port)

Ported seems like the obvious choice so this is my control, but when including the port my box volume tends to get larger than I want. This ones a bit large for me but I think I could make it work. Digs deeper than I need but overall pretty happy.


Finalist 2
Driver : Dayton DCS305-4
Passive Radiator : 1xRSS315-PR
Added Mass : 200g
Total Volume : 1.8cf

I was inspired to look into PRs when I came across the Meniscus Baby Boomer. I tried to match their claimed 30Hz F3 at 1cf but couldn't even get close. This was my best attempt using a single PR, and the PR costs more than the driver which seems a bit silly for me to consider and makes this the most expensive option. I'd also prefer dual PRs for the force cancelling property.


Finalist 3
Driver : Dayton DCS255-4
Passive Radiator : 2xDS315-PR
Added Mass : 200g
Total Volume : 1.3cf

Really happy with how small this is, but a bit of a hump in response. Might increase the box size a bit to try and get rid of it. Cone excursion makes me a touch nervous too but its at such a high power level I don't think it's a realistic issue.


Finalist 4
Driver : Dayton DCS305-4
Passive Radiator : 2xDS315-PR
Added Mass : 300g
Total Volume : 2.0cf

The added mass is right at the limit of what Greg at Dayton Audio said was "safe" but it still makes me a bit nervous. Excursion limits are under control and it digs nice and deep.



My current front runners are 3 and 4, with 3 taking a slight lead due to the smaller size. I might be able to tweak the sizes of both to get excursion and added mass lowered a little bit but I'm curious what I'm forgetting to consider, and what the more experienced individuals would do differently.

I bought this Board with Bluetooth 5.0:




which works great but unfortunately it is always possible to connect devices even when the 3.5mm Aux is connected.
Is ist somehow possible to disable Bluetooth (preferable temporary by switch
disconnecting antenna or something)

The Bluetooth Chip is an "JL" AS20BP00966-25A4 "JL" stands for ZhuHai JieLi Technology Co (珠海市杰理科技股份有限公司-珠海市杰理科技股份有限公司|杰理芯片)

the chips is likely either an AC6905A or AC69025C (most likely last one because of BT5.0)

the chips would have the following pinouts:

OK, I subscribe to a more scientific approach to the idea of what SQ is...In a perfect world a Razor flat system measurement at listening position probably would interest me. etc etc bla bla bla....Perfect flat is not achieved in our rooms (mastering studios control rooms etc) but a best as possible of maybe +/-1.5db in a really critical listening environment? +/-3db elsewhere? I dunno...whatever is possible is fine and not my issue. We use measurement microphones to tune systems. A microphone is not the ear, and there are enough differences to start a whole, other, debate lol....non the less...my point is this! Why wouldn't I be better off, tuning my system, aiming at as flat as possible, using my ear.....instead of a microphone....my thinking is that everyone has there own personal "frequency response" and that with practice....you would achieve an even more natural system FR, than a microphone could....

Maybe using a signal generator?

I can't be the first person to have thought of this and I am curious to where this discussion goes.

Ive been measuring the temperaturs of the heatsinks on the amplifiers ive neen working on over the last few months, and they are all very different, but the one im working on at the moment has a very high temperature (53c)


most i have worked on get up to at most the mid 40's


can this affect transistor performance and eventual quality of output?


so a bit like a PC processor, the hotter it gets the less efficient, without the heatsink and fan it would soon fail, as would the transistors
with the processor it slows as it gets hotter, or too hot and i wondered if the same could happen to BJT'S?

Very newbie question here. I am buying my first line array for small venues (<1000 people).

The Q1 is rated 400W RMS @ 8 ohms. The D12 is rated 800W RMS per channel @ 8 ohms. So in theory, the D12 is able to power exactly 2 loudspeakers per channel. Am I right? The 2nd loudspeaker will be connected in the line-thru of the 1st loudspeaker, and putting the D12 amp in Q1 preset should do the correct impedance and crossover settings, right?

Just want to make sure I am not underpowering or overpowering the speakers.

Thanks

The AEM6000 is an extremely well regarded amplifier making use of Hitachi
lateral MOSFETs. It was designed by David Tilbrook as a successor to the
ETI477, and published in Australian Electronics Monthly in the nineteen
eighties.
With changes in availability of components, the AEM6000 is now extremely
difficult to build. The amplifier was designed prior to the widespread use of
modelling tools, so is not optimised. Additionally it makes use of a large
single-sided PCB, with through-hole components throughout, like most kitset
amplifiers of the period.
This marks my fourth iteration of this amplifier. My first was reasonably faithful
to the original, differing mainly by substituting 2SK1058 and 2SJ162 flatpack
lateral power MOSFETs for the TO-3 devices in the original, plus substituting
an SST-404 dual JFET for the original input JFET. Iteration two was simply a
50W version of iteration one. This and the iteration three design (100W) alters
the topology slightly, dispensing with the differential-symmetrical VAS stage in
favour of a simpler non-differential stage. VAS and second stage transistors
are higher-performance 2SC3503 and 2SA1381, and the compensation
networks and biasing is optimised for increased amplifier speed whilst
reducing quiescent consumption



Power supply 4x4700uF. Bias 65mA,offset 5mV.


Specifications
Power handling: 50W RMS into 8Ω load.
Frequency response: +/- 0.1dB from 20Hz to 20KHz.
Gain 16 (stable with gain as low as 6).
Distortion + Noise: <0.0005% (1KHz, 0.1W to 50W into 8Ω).
<0.003% (10KHz, 0.1W to 50W into 8Ω).
Noise (input referred): 8nV/√Hz (measured at 10KHz, input shorted).
Slew rate: 10V/μs
Input impedance: 100KΩ (set by resistor).
Size: 75mm x 50mm PCB.
Power supply requirement: 2 x 40-60V DC. Lower voltages possible.
Idle power: 5.6W with +/-40V supply.

Price 90€

Good afternoon everyone..Happy 4thof July. So I have never used a Eton tweeter before? I have use seas textile domes.and other planner and tweeter's and the L.G. metal some tweeter's from the past..So I have a few questions? I would really like to use the Eton magnesium ceramic dome model number 29HD2. I also like the sound of the silk Dome model number 28SD1. So can anyone tell me how the Magnesium Ceramic tweeter's sound like?Are they bright or tinging sounding? Thanks Jeff

Hi everyone

I have these Neumann KH120 studio monitors, I quite like the sound but there are some reliability issues.

A while ago one of the monitors died. The problem lies within the smps.

Before that I had a customer bringing another one with the exact same problem, and on the internet there are several reports of smps failures.

I am not inclined in paying the official repair centre to fix the monitor and then having the same problem again at some point in the future.

I won't get much money for the broken speaker so I am starting to think I could have a play with it removing the whole psu + amp board and converting the speaker to passive.

I am totally new to crossover design so I am wondering wether this project would be worthwhile at all.
Very keen in knowing any opinions from who is more experienced in this subject

Here are some specs for the KH120 active monitor

NEUMANN

I've always wondered about how far I should drive breakups.

Some say 20dB is enough, others say 30dB, others go for 40dB or more.

after the driver (eg. Tweeter) overlaps, how much does masking affect the ability to hear these breakups?

Here's my driver + LP filter. Measurement conditions 0.5m, on baffle. Equivalent to 90dB/1m.


Are my breakups adequately suppressed? Perhaps this is one of those things where I need to test empirically with a DSP...

Hello everyone.
I have implemented a version of the LM3886 & ACEBass amplifier on the same circuit using the AudioPRO b1-45 circuit.
I saw an alternative called LEMF, has anyone implemented it? I would like to try it but I am not clear how to do it.
Thank you all.

I consider to sell Tango custom transformers
8k / 600ohm 60H suitable for line output, preamp linestage with 5687 or as I planned - 46 type tube

can size of Xe20s
no discounts, no exchange, fixed price.

550 EUR TOTAL within EU

My journey of using small full range drivers for HF duties has only started in the last year or so. Currently using Fostex ff85wk/SB Acoustic SB13PFCR25-8. Presently I'm crossing high but am also experimenting crossing low around 350 or so. I realize I might be talking heresy but for those that also listen to a lot of classical music, have you found the sparkle of strings and brass slightly veiled when compared to a traditional tweeter? My lineup of traditional tweeters involves a Focal TC90TDX and some Elac products. My implementation of the Fostex may be lacking and I have no measuring/designing capability other than what I can plagarize from forums like this. However, I do have a little background in listening because I was a public school band director for 36 years. Thanks for any and all suggestions.

Hi,

Live in Western Sydney, Australia.
Long time reader and almost first time poster. Have been quietly assimilating information from this and a couple of other great forums.
Several months ago, purchased and built the Elekit Amp and Pre-amp, with upgrades and most recently the Lundahl transformers from Victor. Built birchply bass reflex speakers using the Super 15's from Audio Nirvana in an Ambience set-up. Built a PC with a EVGU audio card, lots of storage and generally play Flac files via JRiver, which works well as I've networked it to be available on several devices/bluetooth speakers throughout the home. Love the phone's ability to remote control the music from anywhere in the home. Also have a Planar turntable (entry level) that sounds a lot better than I think it should.
Room set up isn't ideal (5.5m X 6.5m with a vaulted ceiling) but I hope to move it all to a more ideal area on the near future.
I have a Richtor sub woofer (stolen from my home theater room) and use it with the bass plugs in, along with recently building 2 of the bucket subs which sit in each corner of the room out of the way, driven by a fairly basic dayton audio plate amplifier (they just add that subtle fill-in bass).
I've most recently purchased a Umik mic and started doing measurements, trying to understand REW and adjusting settings in JRiver. Have tried a couple of sets of tubes and gone back to the original ones for the measurements.
I think it's sounding better than ever and continue to thoroughly enjoy the clarity and sound stage as I tinker along...

James

Just a quick introduction!

Been into Audio pretty much the second i entered the earth from my mums whatdoyoumacallit!

Looking for a new install in my Insignia, have something going on now but its needs something else, so ill imagine i will be posting a thread on that in a bit!

Over and out!

I have a design I'm currently designing the build out for. It's a cascode with B+ of -320V to +320V thus the design has separate heater supplies to stay within the heater-cathode limits.

Is there any benefit from twisting/platting/tying the different heater pairs together?

The only issue I could see is ensuring the conductor to conductor insulation is high enough (ie from the lowest heater reference to the highest taking into account any AC peaks). Given they're running off separate isolated secondaries the only other issue is a small amount of capacitance.

It would look neater..

Hello
I have bought a Nord nc500 from my friend butt sadly he dropped it the floor with the male XLR connectors in so it broken pretty bad
The cable inside on the XLR did loose and I can't understand how to get them back
I take som picture and hope someone know how to do!?
Vit for me is the signal bit is the light blue that to or........?
I know how to welder to the XLR , but I don't want to brake my amp.
I'm a hobby electric fixer so I can fix some stuff (I hope this)

All answer will make my day
Tanks PETER from sweden

For sale is a good working pair of Tango ISO NC20F interstage transformers.
Specifications easily available if you Google. They are currently installed on my amplifier. Going to decommission my amp. They are the best interstage transformers i have used so far. Send me a PM with your email if you want see some pictures.

US$850 + delivery cost depending on where you are and the service you choose. Paypal will be the mode of payment.

I just need a few TO-3 sholder washers I could get by with 4 but 10 would be even better.

My monoblocks are progressing nicely. Of course, I would like to advance the cause and tweak the schematic. As a baseline for the monoblock sounds, listening is non-fatiguing, taught bottom end (though not extended as I would like), smooth top end. Tonality is to my liking, natural and no extremes.

But, there is a slight bit of veil over the sound. Just the slightest opaqueness. So slight. So, I have a few ideas that may help remediate this issue. I am considering 3 alternatives, possibly all 3 eventually. Here are some ideas:

1. Replace the existing 100K grid resistor to a grid choke on the C3g.

2. Insert a new choke in front of the RC network feeding the IT / C3g.

3. Insert a new choke in front of the Russian 50uK Ultrapath cap which feeds the OPT.

All 3 of these option are highlighted with the blue boxes on the attached schematic.

I need your thoughts on these 3 options. Are these option expected to materially improve the monoblocks?

Thanks in advance.

View attachment C3g-45B 6.29.21 copy.pdf

Hi everyone,

I have a power amp that has ground hum coming through the speaker of one channel, even with nothing connected. It’s not loud, just about audible from listening position. I have attached a picture of the inside. The channel that’s humming is the speaker output nearest to the power input.

I’m not an electronics expert, but I have tried a few things. I removed some zip ties and moved the power cable away from the audio output cable. I have also used a chop stick to check for any loose components but found none.

Do you have any other ideas to try? I recognise that playing around with certain aspects of the amp can be dangerous, and I will be sure to discharge caps and anything else you suggest.

Thanks.

I've had these since 2010, but at this point I don't think I'll build an amp with these.


(Although it's enough parts for 4 channels, so that would be one cool use case.)


So for sale here are:


5x LME49811



I got these as samples direct from National Semi back in 2010.


I think I also still have the printed invoices with my name on it, if that's enough proof of these being genuine, although I'll have to go to the storage to find it.


--



5x MJE15030G
5x MJE15031G
5x NJL3281DG
5x NJL1302DG


These are the power transistors to be used with Panson's circuit for example. I got these as samples as well from ON Semi.


--


And 4x Panson Audio Labs PCBs 'Compact Series' V2.1



Compact Series


--


The price for everything is 85 EUR + shipping and PayPal fees.


I don't want to divide it up and sell only select parts, maybe if there are two buyers who want to buy 2 channels worth of parts each.


Thanks.

Hello,
I am working on my theoretical skill, and I struggle a bit understanding the geometric interpretation of s-plane regarding eigenfrequency (natural frequency ?) and quality factor.


On this document (cf screenshot), I read that poles at constant frequency move on a circle when modifying the quality factor?
Is it because of this "natural frequency" term ?

It goes strongly against my intuition that constant frequency is equivalent to constant imaginary part of the pole.


http://jahonen.kapsi.fi/Audio/Papers/Equalization.pdf

I am understanding wrong ? is the document a bit inaccurate ?

Would you have some recommendation about resources I could use to understand those thing ? (signal theory, linear stuff, DSP, and so on). I am not too scared of maths, but I really enjoy pedagogical stuff that gives intuitions.

Thank you very much 🙂

Firstly, may apologies as I know very little about musical equipment, and I hope this is not in the wrong thread, but here goes,

Las week i purchased an old sound system. Brand is Toshiba (model number listed above) and it also came with a turntable.

When I brought it home to set up, I noticed the turntable does not have a needle for playing records (stupid, I know, but like I said, I am totally unfamiliar with all this) Are needles easy enough to come by? Do I need a specific one or are there generic ones I can pick up?

Also, when I brought it home and set it up, I tested the radio on it, it works fine but it seems to be stuck on full volume, which is pretty loud to put it mildly. I am looking at the back at all the cables and I may as well be looking at heiroglyphs.

Could anyone please help me and shed some light on these issues?

Thanks in advance,

Stefan

wow!

How vinyl records are trying to go green - BBC News

“There were 22 times more vinyl albums sold in the UK in 2020 than in 2007 - with sales leaping from 210,000 to 4.8 million.
The most recent figures from the British Phonographic Industry reveal sales grew by more than 30% in 2020 alone, bringing in revenue of more than £86m.
For the first time since the late 80s, the value of record sales in 2021 is expected to surpass that of CDs - although it still lags way behind digital streaming and downloads.”

And now we have to worry about the environmental impact, something that was not an agenda item back in the day.

Apparent deficiencies of these models:

The 2SC6145 model has higher apparent Re at higher currents due to difficulty in modeling the curve in the datasheet. Furthermore, the high value of Nk may cause convergence or solver errors. Removing Nk should fix this, and the majority of Hfe droop is due to quasi-saturation anyway.

(I'm sure there are more deficiencies, but those are the apparent ones.)

.model 2SC6145-Y_kq NPN ; Revision 3 by keantoken - March 1 2019
+ Bf=93 Br=8 Re=8m Rc=16m
+ Rb=4 Rbm=0 Irb=0.3 Vaf=1000
+ Is=5p Ise=200f Ikf=200 Nk=1.9
+ Rco=0.68 Gamma=255n Vo=100 quasimod=1 Qco=100p
+ Tf=2.45n Cje=9.7n Cjc=880p Vje=0.68 Mjc=0.48 Fc=0.9
+ Xtf=30 Itf=15 Vtf=0.95 Xtb=0.9 Eg=1.16
+ Vceo=230 Icrating=15A mfg=Sanken
.model 2SA2223-Y_kq PNP ; Revision 3 by keantoken - March 1 2019
+ Bf=99 Br=8 Re=10m Rc=18m
+ Rb=2.38 Rbm=0 Irb=0.9 Vaf=500
+ Is=3.5p Ise=50f Ikf=3 Nk=0.15
+ Rco=395m gamma=14n Vo=30 quasimod=1 Qco=100p
+ Tf=3.65n Cje=8.3n Cjc=1.6n Vje=0.68 Mjc=0.48 Fc=0.9
+ Xtf=50 Itf=110 Vtf=2.6 Xtb=1.4 Eg=1.16
+ Vceo=230 Icrating=15A mfg=Sanken


Revision 3 - Updated Ft behavior with measure capacitance values thanks to astx.

I like the C4883/A1859 from Sanken, and have tried to model them well using the datasheet. It was tricky, but I'm pretty satisfied. I matched Vbeon, Ft, Hfe and quasi-saturation. Adding quasi-saturation makes Ft and Hfe MUCH more accurate, so I'd say this is in a new league of SPICE models.

The behavior shown in the datasheets is what I modeled, so I'm not sure about Early voltage or Hfe slope at higher voltages, but I think everything is close enough for a practical simulation, especially with quasi-saturation added.

Notice that the Vbeon curve on the datasheet specifies Tc=25C. If Tc is held constant, that means Tj increases with Ic! So I had to estimate the tempco and subtract that in order to get a match.

Where the Hfe chart and the Vce chart disagreed, I went with the Vce chart since it seemed more detailed. The discrepancy was not small at all!

.MODEL 2SC4883A_kq npn (Bf=140 Ikf=100 Is=600f Vaf=100
+ Rb=1.7 Re=105m RC=0 Rco=6 Ibc=150f Vo=30 Gamma=250n
+ Cje=1.2n Cjc=72p Tf=875p Vtf=1.2 Itf=1 Qco=8p
+ Nk=1.2 Br=2 Var=22.9 Ikr=36 TR=85n
+ Xtb=0.34 Xtf=1.36
+ Vceo=180 Icrating=2A mfg=Sanken)
.MODEL 2SA1859A_kq pnp (Bf=162 IKF=10 Is=500f Vaf=300
+ Rb=0 Re=0 Rc=90m Rco=3.25 Ibc=150f Vo=120 Gamma=22n
+ Cje=1.5n Cjc=72p Tf=1.9n Vtf=1.9 Itf=1 Qco=8p
+ Br=2 Ikr=10 Var=23 Tr=188.8n
+ Xtb=0.138 Xtf=5
+ Vceo=180 Icrating=2A mfg=Sanken)

I’m currently building an f6 and am looking for a preamp.
Suggestions please

Hi,
I have just finished my new valve amp and I am now aware that there is a large inrush current.

Here the HT is connected to a GZ34 and then CLC, and the filament supplies a Rod Coleman regulator.
The question I have is, can I just add a thermistor straight after the plug (as shown above), and if so, can someone tell me exactly which thermistor I should use?
Thank you so much - I feel very old to be a noob, but hey ho.
Thanks again
Bass

Hello, working on a T1000-1bdcp. Power supply was smoked so I replaced power supply mosfets, output mosfets, 2 transistors on ps card, all three rail caps, and r200 on bd card. The amp powers up and plays but is drawing 3.6 amps at idle. The amp has a small speaker pop on turn on and draws less current when gain is turned up and as gain goes up I am getting a whine in speaker. Any advice? I have swapped a known good ps card and bd card with no changes.

How many parameters would need to be tested so that two or more amplifiers with all results matching could be considered to be identical soundwise?

Looking at various audio test equipment manufacturers' websites, I come up with this quick list.

Gain
Sensitivity
Power
Frequency response
Bandwidth
Phase Shift
Input Impedance
Output impedance
Slew Rate
Distortion (THD,IMD,TID)
Distortion vs. Output
Signal to Noise Ratio
Crosstalk

Anything else?

and if an extensive data base of all measured amplifiers existed, would it even be possible to find two designs that match on all the tested parameters?
If so, Would those amps sound identical?

I bought a 556 this morning. It has 5 extra modules and the stock tilt cart too and all the probes and manuals. Is it a good Oscope

I found a DIY audio site for India region, they are selling prebuilt Dayton speakers and other DIY speaker kits but they don't have any stereo amplifiers, prebuilt or DIY kits, they are selling individual components, are there any schematics available for stereo amplifiers online, I can use to build them? Some DIY speaker kits come with cabinets, some don't, which would be better, if I buy just the transducers, capacitor kits, can anyone here tell me what dimensions the speaker cabinet should be? All DIY speaker kits come with soft dome or hard dome tweeters, the prebuilt Dayton speakers come with Air Motion Transformer tweeters, which is better?

I realize that I'm a little off topic here, not being specific to audio power. This trafo is however going to be used to power an aluminum casting furnace that is to be used for casting misc. audio components.

Here's what I need:
110V 1phase primary to around 1-6 volts secondary, with high current handling on the secondary.

What I did:
Coiled a 5" wide 'slit' of Arnon7 NGOES electrical steel into approx. 4.5 ID x 6 OD by 5" tall. Taped in place using high temp. flash tape. Wrapped single layer of aluminized fiberglass and taped in place with flash tape. Wound 12awg magnet wire to 110 turns. Wound 4awg single turn secondary. Applied power....SPARKS. Removed secondary and checked for shorts. No shorts found. Added 30amp fuse wire to primary (plus 20amp mains breaker) (no secondary winding) and applied power. No fuses/breakers tripped but the enamel burned off at exactly the mid point in the winding. This further confirms my belief that a short is not the issue (regarding bare wires in contact, I mean).

Okay, now what? The main thing I am aware of is that my aspect ratio is very bad, approx 1:1. And I know that 2:1 is optimal, or 1:2, depending on how you frame the definition. Is this the issue? Or am I way off kilter elsewhere too? I know that the Arnon material is pretty exotic stuff so maybe that is not helping matters either?

What to do? I had originally planned to coil the Arnon and then saw it into two cores for the ideal geometry, will that perhaps solve the problem?

Anyone built these, or have any opinions on them?

Voxativ AC–1a PRODUCTS



Quote from their website

AC-1a drivers
1,799.00 EURO
(Note: pricing is for a selected pair of drivers)

The newest entry-level Voxativ 8-inch full-range driver is equipped with a specific array of neodymium pill magnets to enhance bass response.

Each pair is delivered with the build plans for the 'New Acousta' back-loaded horn inspired by the original prototype loudspeakers built by Inés Adler that culminated in the birth of Voxativ.

This model also offers great resolution and best bass response when used in a Hagen Monitor or Tower configuration with or without Absolut system configuration.

Technical Details

Frequency Response
20 - 20.000 Hz

Efficiency
96dB (3 kHz) 1W / 1m*

Capacity
50 W nom / 100 W mus

Impedance
10,3 Ohm

Qts
0,46

Depth
3,2“ / 8,1 cm

Diameter
7,5“ / 19 cm

Weight
2,4 kg / 6,0 lbs

Sales price is for one selected pair and includes a digital download of build plans for the New Acousta.

Hello all. I've got isssues with a Sundown SAZ500D preamp board. It is not outputting any audio to the driver card. I recently solved this problem by swapping out IC102 (JRC074D) and it worked. However,the driver card failed and since then ths preamp board is no longer producing any audio. I replaced this IC again but now, I've got 6.2V of DC on pin 14 of this IC and no audio. (According to the datasheet, pin 14 should be output 4). When i crank the gain, bass and sub knobs all the way to the max, there is a small half of a sine wave riding along the 6.2V of DC but that only appears when i turn the gain, sub and bass boost pots all the wat too the max. I have swapped out this IC 6 times for brand new TL074 ICs and everytime i drop it in, the DC reappears in pin 14 and no audio. However, with the IC removed, I've got -0.6V on pad 14, -0.7V on pin 13(input 4). On all the other pads which are supposed to have audio (according to the 074 datasheet), there are sine waves present, but there are no waves present on 13 input. Can anyone advise me here on what else to check? I have got two of these preamp boards with the exact same problem. Will attach a schematic and some videos for reference if i can.

Hi
Looking to swap my Sonicaps Gen I, in like new condition, 12uF @ 200V, for 10uF, same brand or similar brands ok. Need 4 caps.
Thx

Amp in photo.
TPA3255 in 2.1 mode, 2 satellite channels and subwoofer channel
TPA3251 in 2.0 mode.
All amp have PFFB
PSU LLC, 48V for TPA3255, 35V for TPA3251 , auxiliary +20v and +- 20v
AMP+PSU $140+ delivery

BOTH OF THESE AMPS ARE SOLD
THANKS FOR THE INTEREST !



I have 2 Diy f5's for sale, both work great,were in my HT bi-amped decided need more Headroom so off they go asking $375 each plus shipping

Hi folks


My Arcam Alpha one CDP has stopped reading disks. With no disk in the machine it displays 'disk'. When a disk is inserted it spins it up and tried to read it, during this time it displays '01' then the display returns to 'disk' and it has failed to read the disk.

I'm wondering if I should replace all the electrolytic caps in the servo section?

Or is it much more likely that it is the laser that has failed?

Is there a procedure to potentially diagnose the issue?


The SM is particularly unhelpful and just says send it back to ARCAM for repair:

Hello,

I have a Pioneer PDR-555RW that does not want to load a CD.
The player shows "CD - CD-R - CDRW - CHECK DISC" and that's all.


The error code is:

0255 P6

P6 = The unit does not read the inserted disc and stops. (CHECK DISC display) / TOC READ

84300008

*4 = TOC, PMA read (including SETUP)
30 = TOC area search
00 = -
08 = "Improper A/D value of RFT, RFB"




What I figured out so far:

Having this unit set to the test mode, I have no problems playing a pressed CD. But I am not able to play a CD-R in test mode.
So maybe that is the reason the player is not able to detect the medium?

In another thread, I read about cleaning the TOC Switch S601 but that does not change anything.
According to the service manual, I should check PC651.

Maybe someone has a hint or an idea.




Greetings,
Klaus

Morning all,

I have in my possession LM3875 kits from Audio Sector + 330VA toroids (25v).

The kits are fully built and used by the previous owner. I sadly never got around to it. Looking for $100/kit (including the xfmr) + shipping. I can do package deals if wanted 🙂

Does Onsemi charge shipping to the US, or only to Canada?

Which orientation (1 or 2) is better in terms of radiated stray field?
The audio modules are to the left of the transformers.
The closest audio module is diagonally, down/left.
The big pcb to the left is the PSU

Regards

Had these drivers sitting my shed for months, they will eventually be part of a 3.5 way, but had to see how they sound. SB15MFC -4 & SB21SDC tweeters, Xover 3KHz, in 11 Litres tuned to 44Hz for an F3 of 43. (I didn't use the 0.39 ohm R in series with the tweeter) Sound remarkable, great clarity on vocals, & impressive low mids for Double bass, handle metal (Ningen Isu) well until they are wound up quite high. Really impressed by the MFC drivers.
The 18mm ply boxes are recycled, I should know from experience that it's easier to start from scratch, but I'm genetically programmed as a tightarse. So this evening, time to set them up properly in the room, pour a Glenmorangie, & settle down for a session....

For the 3.5 way, lower mids will be SEAS CA18RLY, and for woofers, not sure possibly 2x SB20PFC, or this Altronics 10";
C3026 - Redback 250mm (10") 120W Woofer PECC Speaker - Altronics

I have a number of ICEPower 1000ASP amplifier modules which have been great, however two of the last 3 I've bought have failed.

They appear to struggle to start up like they're trying every second, failing and trying again; the LED flicking green and orange constantly.
Has anyone else had this problem? I'm wondering if there's perhaps been a bad batch lately, etc?

Cheers
Benno

Triode Strapped Curves generated for 6BM8 Pentode

Hi All,

The 6BM8 contains a high mu line-level triode and medium power pentode (Pa ~7W) in one convenient glass envelope.

I made some rough triode curves for the pentode section. They can be found here:

Triode Strapped Curves for the 6BM8 Pentode – Greg's Stuff

Hope someone finds them useful.

Cheers,

Greg

Folks:

About 15 years ago, Bas Horneman hosted a couple of group buys for Aikido preamplifier pcbs (as I recall, this was before John Broskie began selling boards). I built a noval Aikido using Bas's boards and have been very satisfied with that project until very recently, when a few component changes were made to my tube system. The problem now is that the gain is too high, perhaps by 6 - 10 dB.

I'm no expert in tube topologies and have no clue as to how to reduce the gain on my Aikido. For me, the ideal solution will be as simple as possible and will not degrade the sonics of this preamp.

In my Aikido, T1 are 6N1P and T2 are 6H30. Would swapping or replacing the tubes be a solution?

Your advice is greatly appreciated!

Regards,
Scott

I am looking for a subwoofer driver recommendation to be used in a custom sealed enclosure in my Jeep Wrangler.

A link for the enclosure:
2007-2018 (Passenger Side) Jeep Wrangler JKU 10" Rhino Coated Subwoofer Box Sealed-Sold in singles. - BRP AUTO DESIGNS

They make enclosures for a 10-in and a 12-inch subwoofer. Both enclosures have 0.75 cubic feet of air space. I am going to be powering this driver with the subwoofer channel of an Alpine pdr-v75. The amp produces 250 watts at 4 ohms and 350 at 2 ohms. So unless there is a significant efficiency advantage for the 4 ohm driver I'd like to stick with drivers that are capable of providing a 2ohm load. My primary goal is to provide balanced sound through the system and I would prefer low-end extension and musicality over total output.

The modeling I have done so far shows that a good performing 10-in subwoofer will provide better low-end extension in the small sealed enclosure that I am confined to without a bunch of eq.

The best driver I have found at the moment is this.
Dayton Audio RSS265HO-44 10" Reference HO DVC Subwoofer

Price is not a huge concern but I would need significant convincing to spend more than $200 on the driver. I have been out of the audio game for several years now and I'm open to suggestions. I'm also completely open to a 12-in driver if I can make it work, perhaps I'm running the modeling wrong as it seems counter-intuitive that a 10-in driver would provide better low-end extension. Thanks in advanced.

I'm ordering parts for a 6L6 PP UL amplifier. I'll be using a toroidal transformer.
I would like to see some different ways people have mounted them. I've used the metal pill box, square covers, etc. I would like to mount it vertically this time. I've seen the U shaped and L brackets. But I would like to do something different. I want to maybe use rod end bolts. One on each side with a bolt going through the middle of the transformer. But I can't find anything like a 5" diameter shrink tubing to cover the mylar covering of the transformer.
I would like to wind up with a more finished look. I've been looking for something like a plastic clam shell to cover the windings. So what have others here done to mount a toroidal transformer vertically?

Hi all,

We just recently moved to Tokyo during the limited window for foreigners to enter. I was wondering if anyone knew of any audio clubs in Tokyo?

Unfortunately, I do not speak Japanese so English friendly clubs would be even better!

Thanks in advance if anyone has any recommendations.

Regards,
PM

I have an Usher R1.5, from what I read, it is a close copy of Thresholds/Pass' Stasis S300 amp. The Usher is 50 watts Class A / 150 watts Class AB

To get 50 watts Class A, I would need to bump up the bias and ensure that the heatsinks are at 50c. When I got my amp, it was idling at 36c. My infrared thermometer's upper limit is 42c, so I biased the amp up to 42c. New infrared thermometer with 100c upper limit is on order. I am familiar with Nelson Pass' 10 second hand rule on measuring temp on the heat sink, but do not want to take a chance right now 🙂

Will there be a noticeable improvement in sound quality once I get to 50c?

What happens if a put two small fans on each side to cool the heatsink, aside from cooling the heatsinks, will it have a negative effect on sound quality?

Hello,

I've a NAD 6155 C-cassette player dated back to 1986, with a power transformer which I fried few days ago (too hot hereabout for its primary winding...). And as one may guess finding spare parts seems to be quite a problem. Based on the schematics (or rather the voltage ratings of the ripple capacitors) I've guessed that it has a 2-winding secondary with outputs of 12V-0V and 24V-0V-24V. My question is that if there happens to be accurate voltage readings for this transformer, if it's a common type (PTX- 263E) or taylor-made for NAD , and what if it's replaced by eg.t wo toroid trafos, one cnter tapped 24V-0V-24V, and another 0V-24V. Based on the fuses, 500mA only, these are pretty small and fit well in the original sheet metal box. It seems that multi-tapped transformers are quite difficult to find nowadays.

Looking for some advice on a failed EM8810 PCI Card. That is the PCI card for the E-MU (Creative Professional) 1820/1820m and also can be used with 1212/1212m.

In systems where it previously worked (with all the W10 driver fixes) it is no longer recognized by the driver installation. It shows up in device manager but not as the EMU E-DSP. It is now an unknown device from unknown manufacturer. Just FYI the same (multiple systems) still work fine with my EM8960 PCI card for my 1616m. So I believe the software/drivers/machines are ok.

With quite a bit of searching I came up with someone else (in Russian) with a similar problem that they fixed on their EM8810 by reflashing the 93C46 EEPROM. It seems that EEPROM corruption occurs sometimes with the EM8810 (E-MU 1820/1212) and some other Creative products (such as AWE64).

My searches reveal EM8810 EEPROM corruption here: (See post 53) [I used Google Chrome to translate to English.]
??????? ???????? ? E-MU 0404 PCI - ???????? 3

And AWE64 EEPROM corruption here:
Creative PnP EEPROM collection \
VOGONS



Does anyone have any experience fixing such a problem? I am thinking of trying to use an Amazon CH341A EEPROM programmer with a clip.

The EM8810 board has a "CSI 93C46S" which I believe is a 5V CAT93C46S (Catalyst) EEPROM.

I probed the Vcc and GND pins and they are connected to what appears to be the 5V and GND pins of the PCI card. (5V being the last pins furthest from the bracket on the 32-bit card.)



Should I hazard this repair attempt (this way)? Or should I de-solder the chip and program it off the board to be safer?

I have attached a picture of the programmer and of a EM8810 PCI board.

Did someone use Peerless/Tymphany PLS-P830985 ?

Hi everybody.
This is my first real project and it didn't gone well.

I purchased 2 Peerless PLS-P830985, 2.5 inch,
and made boxes (plywood, 12mm) with 1.6 liter inner volume.
Speakers mounted from inside.

I haven't made a port and sealed them properly yet, as I'm waiting for some router bits.
But I have just assembled the thing, and it sounds like ... crap.
Ok no bass - that's predictable. But the sound in the middle is somehow not "opened" and the heights are the worst. Especially in dancing music the beat with "ts" and "ch" almost hurt the ears. And it looks like these drivers play these sounds "ts" and "ch" even if they are not in the music.

I first tried them with D-class amp (cheap amp from aliexpress, works from usb, 2*3 Watt, I don't recommend it either). Then with my good-old Rotel RA-935BX and compared against B&W 602.5.
Again, no comparison of low frequencies, but the rest also just sucks.
The worst is that the sound is very unpleasant for the ear.
Some small multimedia from Microlab/Sven/Edifier for comparable price would be waaay better.

I'd like to hear other experiences with these speakers. Am I doing something wrong?




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Hi Guys,
I was planning to build Troel's 18W ()
Flat panel and crossover V2 sealed.

I know Troels explicitly writes that have to go ported because of the high Q, and I'd say that's right, but I suppose a sub could solve the issue.
They will be on the wall beside the TV (Stands are not an option) so the reduced bass may be a good thing.

Madisons suggests 6l sealed F3 100hz and it could work as midbass with dedicated 10" woofer, but directly to a sub seems too high.
Winisd gives me a Q of 7.07 at 12.5l and this is the max space I can spare, so that could work.
What size would work better in your opinion? (conected to AVR, No proper DSP) should I aim at a slightly higher Q?

50/50 Movie/Rock Music

Thanks!

Will some short-term, DC offset (< 1 second, about 250mV max) at the phono input damage a moving coil cartridge? After a second, there is zero DC offset.

I could use some help solving an issue with the pitch control on a Technics SL-M1.

To start, the service manual I have for the SL-M1 doesn't show a pitch control or the associated circuit, which leads me to believe that this feature was added to later models. So I'm flying a little blind here.The circuit in the SL-M2 appears to be similar, so I'm basing what follows off of that.

The issue is that I can't center the zero position on the pitch control. Per the service manual for the SL-M2, with the pitch slider (VR401) at zero and a frequency counter connected to test point TP27, you should adjust VR301 for between 262.075 kHz and 262.085 kHz. The closest I can come is 250.833 kHz, and that's with VR301 all the way clockwise (zero ohms). Of course, if I move the pitch slider from the physical center position, I can get the frequency dialed in correctly, but not until the slider is nearly all the way to the left.

This circuit is also similar to that of the Technics 1200 MK2, though neither the SL-M1 or SL-M2 have a pot for adjusting the pitch control gain like the 1200 does.

I've cleaned the fader with Deoxit F5, and it acts the same as before.

More data, FWIW:

IC301, pin 2: 1.9V
R301: 1.49k ohms

Adam explains to us about the formation of KLOS Guitars and how they're made. He and his brother Ian's formal education of Electrical & Mechanical Engineering have certainly helped their journey of KLOS Guitars. They have also started a company called Skill Board USA for the ultimate in human balance control.

Carbon Fiber Guitars | KLOS Guitars | Skill Board USA | Ep 33 - YouTube

I'm using bench supplies to prototype an amp design, and I'm about ready to move on to the power supply. Plan is 400V B+, 350V drivers, and 250V screens. B+ and screens will each have a simple MOSFET-based series regulator with their own VR tubes for voltage reference, and the driver supply will pull from the B+ with an RC filter. The PT will be set up as full-wave, with a zener string in the center tap connection for bias supply.

I've verified these current draws using an inline ammeter set for DC amps:

• 160 mA plates
• 35 mA screens
• 10 mA drivers

In addition, I'll be sinking ~10mA apiece into the two VR tubes. So by my math, that's 225mA total.

When I modeled it out in LTspice, RMS current at each rectifier diode was over 400 mA. So, questions:

• Which current figure is the correct one for sizing the transformer? IOW, is a transformer like the Antek AS-3T350, rated for 400mA per HV winding, sufficient?
• Which current figure is the correct one for sizing the rectifiers? I'm looking at using a pair of 6DM4A, a diode rated at 200mA continuous.

Thanks!

I have a Haffler DH220 that I want to recap. While I'd doing that, I'd like to use an integrated amp to replace it. The Haffler will likely be on the bench for a few weeks while I make a parts list, order parts, and in general find the free time to do the maintenance on it.


I'm pretty sure I can just run a pre-amp into an input on the integrated amp and set the volume control on the integrated amp to some fixed level (say 3/4).

In looking at the schematic for the input section of the integrated amp (first attachment), it looks like the signal pass is from the input to a buffer (2604 op-amps, U1A/U12) and then to the attenuator (the LM1972, U22). The outputs from the attenuator go to another set of buffers and then on to the amplification stages (2nd attachment).


Since the LM1972 only attenuates and doesn't have any gain, this seems like a safe bet....but I thought I'd check first.


Thanks,


James

LC Audio ZAPsolute Mk4

This kit looks interesting. Supposedly a highend class A amp.

Does anyone know anything about this kit? See
(www.diycable.com/LC_audio_zapsolute_amp.htm)

Thanks in advance for any information!

Gavin

I'm new to audio repair, but not to electronics in general and built a headphone amp once.

Anyway, i decided I wanted to learn to repair amplifiers so I picked up a "for parts or repair" Primare I20.

It would power up and the display and pre-amp section seemed fine, but had no output.

Once I had it home, I started testing the voltage at the test points on the board. My guess was a power supply issue as this is a dual mono amp and other than the pre-amp, nothing else is shared across both channels.

The -14v supply was low (high since it's a negative supply?) at almost 0v. I also notice the +6.1v supply was low at about 1v. at a 7v test point right before the zener.

Checking the voltage at the input of the negative voltage regulator, I had close to 0v. As a comparison, the positive regulator had about 36v at its input. Voltage before R2 was -40v. I removed C8 as I assumed it was shorted. After doing that the input voltage jumped to -36v, but the output was still low at about -7v.

I removed C34 and that fixed the output voltage issue.

Moving on the the +7v supply, in similar fashion I removed C10 and that fixed the problem.

So I have 3 caps to replace C8 and C10 are both tantalum caps, and C34 is an aluminum electrolytic.

I have 2 questions:

1. Any brand recommendations for capacitors. I think I got a pretty good deal on the amp ($180) and the cost of better caps isn't going to break my budget.
2. Is there anything else I should be checking? From the schematic, it doesn't look like there is much around these caps to check. The resistors seem fine. I also believe the diodes are fine and they seem to be there to protect the regulators from reverse voltage. I'll order some regulators since they are both relatively cheap and common and will likely get used on some other project if not needed here.

My plan for this is to use it to replace a Haffler I want to recap. Then maybe I'll sell it as I'm hoping to pick up something else to work on.

Hi


we replaced a couple of capacitors in a BMW 325is stereo. One was bad. The sound is good now but the heat sink at the back of the unit gets really hot after about 15 minutes of playing. It's made by Alpine I understand. I didn't put any new heat dissipating paste on when we reassembled the deck. Could that be the reason or can there be anything else? Thanks for any advice


Peter

They just lay here and collecting dust.
The condition of the tubes is that I dont really remember.
I swapt a pair that was burnt out with this 2 ,and I cant recal they where
used for many ours.
If anyone wants them you only have to pay for the shipping.

Reposting (sort of) from Tubes/Valves -

Hi all,

I have a 3-year old JTM45 Metropoulous/Valvestorm kit that had a failure of the rectifier a week ago. It also took out one or both output tubes (KT66's).

This is the second time this has occurred, but the first time the output tubes were OK.

From what I have learned on the other forum:
1. Do not use standby (because of cathode stripping?): Already aware of that, I almost never use standby
2. Excess capacitance causes excess surge current at power up this. I am using the standard Marshall design, 32uF before and after the choke. This might be too much for a modern (sic) 5AR4?
3. This amp for some reason has pretty high B+ of 500VDC but that has not been flagged as an issue.
4. There are better 5AR4's that the Sovteks I have... I have read that there are some good chinese ones...

From the advice I received and reading more I see a few options:
1) reduce the capacitance prior to the choke for 32uF total
2) install resistors (47ohm) between the transformer and plates
3) install thermistor (Amphenol CL-90) either on the primary or secondary side of the transformer or in series with the standby switch
4) Use a different rectifier brand (which I really don't want to do as I have two brand new Sovteks.

Is there any other know solution to this issue? My inclination is to try 1) and 3) on the primary side together.

TIA/Tim

Title says it all, I need 1 Harbeth LF5 MK3 speaker chassis to repair my fathers speakers.







Let me know if you have one for sale.

I can't seem to find anything about that subject either here or on tubes ,
would be greatful if you knowledgeable guys could chime in a bit on that to enlighten a total noob as meself 🙂

So simply, what would be the result of using a large quantity of smaller diameter woofers or midranges against using traditional single dual or few pretty large woofers/subwoofers .

Not trying to go into specifics here, only trying to understand how all this works slowly so my little brain can process it one bit at a time

This questioning came to mind when trying to understand relation between mass of drivers ( moving mass ? ) vs speed and sound pressure .

Wouldn't a multitude of lower mass drivers have better response and decay than a much larger single unit for the same perceived volume ?

Thanks for your time 🙂

Greetings, Friends. I'd like to share a few pics of my new amplifier.



I've been dabbling in tubes since last spring and after building a few phono preamps and power amps I figured I'd try to build a guitar amp, and where else to start but the Champ 5E1. This one's tiny, a 12x12" box made of 1x6 with a 6" Jensen Mod speaker. The Speaker had to be offset from center quite a bit to accommodate the iron on the back of the amp chassis, and the baffle is two pieces of 1/4" Fir plywood glued together. It's tight in there. Chassis is a Hammond box, 1444-12 7x5x2" but next time I'll get a 1444-14, 9x5x2" for a little more room.



I decided to mix things up by substituting the regular output and preamp tubes for their Soviet counterparts, having built up a stockpile of them through the purchase of DIY kits available from many online resellers. The rectifier tube is still the 5Y3, but the output is a 6p1p and the preamp tube is the 6N2. I had been under the assumption that the 6p1p had similar numbers to the 6v6 and built the circuit to spec with a Hammond 290ax PT and 4h choke and 8w SE OPT from a custom builder out of St Louis. All 3 EL caps are 10uF 500v and I was seeing 320v at the first cap, 315v at b+ and 310v on the plate of the 6p1p. Perfect for a 6v6, but now that I can read tube charts a little, I think the 6p1p isn't meant to see more than 250v on the plate.



So I need to drop the b+ enough to get to a safe operating point for the 6p1p. I've seen on a few forums that the old Winged C tubes can take plenty of abuse, but I don't wanna kill them early either. I've put a pair of 270R 6.5w power resistors on the HV lines going into the rectifier and that got the plate voltage down to 295v, b+ at 298v. I'm not seeing any red plating or anything like that, and the amp sounds good at the volumes I can get away with here at home. What would you do? Any other advice?

thanks!