Roberto 4/22/2018 2:13 AM
Trace Elliot AH1000-12 schematic needed
Hi,

I've bought a Trace Elliot AH1000-12 with one power amp module blown.
Is there someone that can share its schematic?

I would like to repair it, otherwise to substitute it with two class D power amp modules, keeping the power supply as is. Due to the higher efficiency of class d amps, there will be two paths: keep the same output power and make the power supply's life easier, or increase a bit the possible output power. I'd go for the former, as 1000 W are absolutely more than what I'll never use.

Thank you in advance
 
Roberto 4/22/2018 2:46 AM
I've found this link: https://elektrotanya.com/trace-ellio.../download.html
But there's not everything. Has someone ever substitued those power amp modules with something different?

Thanks!
 
Jazz P Bass 4/22/2018 10:02 AM
If you do not need the full 1000 watt output power, then why do you not simply run the one amplifier at 500 watts?

I would disconnect any power leads going to the dead module.

[ATTACH=CONFIG]48578[/ATTACH]

Edit: have you checked the fuses?

I had one of these a while back with a 'dead' module and the fault turned out to be the Speakon output connector, not the amp.
 
J M Fahey 4/22/2018 11:35 AM
Quote Originally Posted by Roberto View Post
I've bought a Trace Elliot AH1000-12 with one power amp module blown.
Is there someone that can share its schematic?
When was yours made?
Manufacturers keep famous bestselling names but change guts now and then; older ones had Class AB "analog" Lateral MosFet outputs, big heatsinks and heavy power transformers, modern ones use lightweight SMPS and Class D power amps, show your amp guts to be certain.
Front panel and general cosmetics may be the same.
I would like to repair it, otherwise to substitute it with two class D power amp modules, keeping the power supply as is. Due to the higher efficiency of class d amps, there will be two paths: keep the same output power and make the power supply's life easier, or increase a bit the possible output power. I'd go for the former, as 1000 W are absolutely more than what I'll never use.
No, just one path: same power with colder amp.
Power supply defines output power, the power amp is just the "faucet" which sends more or less of it to the speakers.
 
Roberto 4/22/2018 1:24 PM
Thanks for the feedback Jazz P Bass. Im sure its dead because I bought from a guy who tried to fix it, and almost destroyed that module. I would prefer to find two class d substitutes for those modules instead of running just one module.

Have you ever done something similar?

Thanks in advance
 
Roberto 4/22/2018 1:27 PM
Thanks J M Fahey,

I have the one with the heavy big thoroidal and the two modules with class AB mosfets.
 
J M Fahey 4/22/2018 3:26 PM
Ok, how many MosFets per board?

They use the same circuit in all amps , not their own desigh but a Hitachi MosFet application example, straight from the datasheet, just with various supply voltages and more or less output transistors.

Largest I have ir AH500 , meaning 2 x 250W modules with 4 MosFets each; suspect yours is same but with 6 transistors per module.
At least similar Ashdown Mag 500 has the same circuit with one module and 6 transistors.
Nothing new under the Sun.

Check whether this roughly matches what you have.

[ATTACH=CONFIG]48585[/ATTACH]

personally I would repair the dead module, to the extent of cloning its PCB if original is destroyed, go figure.
It is a very simple and nrobust amplifier, eqasy to service in the future, and you already have all the hardware mounted in the proper place (specially heatsinks).

Worst case go the Class D route, but you will have to mechanically adapt them to fit "inside a suit made for somebody else" and consider them disposable if anything happens.

Or plain pull the dead Class AB module and just use the working 500W one , as suggested above.
 
Roberto 4/23/2018 9:33 AM
Hi Juan Manuel,

I'll be out for the entire week, I will give you the right answers (and maybe a photo) this weekend.
I remember six or eight MosFets, but I want to give you a correct answer not to waste your time.

Clone the PCB would a bit over my capabilities, also because alot of components on the power amp are smd.
I will give you better answers in a few days.
 
J M Fahey 4/23/2018 4:57 PM
Ok, I was thinking you might have the earliest ones which used through hole components.
 
Roberto 4/24/2018 9:11 AM
I've found a photo of an amp like mine, it's actually the same Jazz P Bass posted few posts ago.
Power amp modules are a mix of SMD and hole through.
 
Roberto 4/29/2018 2:09 PM
Some more photos of the broken module (more on the following posts).
 
Roberto 4/29/2018 2:11 PM
Some more will follow
 
Roberto 4/29/2018 2:12 PM
Some more...
 
Roberto 4/29/2018 2:14 PM
Even more...
 
Roberto 4/29/2018 2:15 PM
Last triplet of photos.
 
J M Fahey 4/30/2018 12:01 AM
Oh sh*t, those are Class D modules.
I had thought you had one of the earlier ones, similar to the schematic I posted above, which *are* repairable, very simple amps.
I consider these ones disposable.
One failed? ... just disconnect it and use the other, which still has huge power.
 
Roberto 4/30/2018 1:25 AM
Thanks Juan Manuel,

imagine to have both modules broken (insert apotropaic gesture here), what would you do?
As you can see in the same module there are:
- rectifier and power supply;
- part of the preamp module;
- clip detection;
- etc...
 
MarkusBass 4/30/2018 1:39 AM
If you want to fix the module, start with cleaning it . Then look for visible problems like the one posted below.
[ATTACH=CONFIG]48690[/ATTACH]

You are in a very good position because you have the other module working correctly and you have the schematic.

Mark
 
J M Fahey 4/30/2018 2:14 AM
I *think* the following, lots of educated guessing and of course subject to verification:

1) the Elektrotanya set of schematics contain both preamps (7 and 12 band) , lots of auxiliary circuits, some cntainibg less than half a dozen parts, but not a word on power amps and supplies.

2) I suppose these were kept because they are the core of the SWR sound but power amps and supplies varied along the years, so the design was modular from Day 1.
Specially because even in the old Analog Mosfet amp days, same 2 preamp variations were mated to a lot of (very similar by the way) power amps, from single 150W (AH150) to top of the line AH500 (2 x 250W modules) and *maybe* a model I never saw but is very predictable, a 400/500W single module but with probably 6 Mosfets, still Class AB.

3) so maybe at some time they decided to fit *two* 500W power modules, but considering thermal dissipation they went Class D . Funny they kept the very heavy (and probably very expensive) toroidal transformer, but hey, they are probably going "one step at a time".

4) It can be independent, but I guess they included the Preamp supply together with the main power amp one.
Check what they actually did, specially now that at least 1 power amp and supply is still alive, draw connector pinout and voltages feeding Preamp, so the day this module dies you can feed bthe preamp some other way.
No big deal, consumption is low, but pre-knowing it may save you time if/when you need it, and your amp does not turn on.

5) IF the current module dies, junk both, build a preamp supply and in the now free real estate space searfch for some power module you like.
I would go the full Monty, get one with self contained SMPS power supply and also ditch the heavy Toroid.

For example, IcePower modules , very popular today and used by Fender, G&K, Aguilar, TC Electronics, Kustom and probably quite a few more, are straight fed 120 or 240V, provide lots of power, and also generate +/-28V for preamp use, which of course can be regulated down to whatevers needed.

[IMG]http://i37.servimg.com/u/f37/16/27/91/69/scheda10.jpg[/IMG]
 
MarkusBass 4/30/2018 2:28 AM
That's strange because I see the power amp and the power supply schematic in the download. Maybe a processor board that controls all the modules is missing but maybe they designed it without a processor.
Here it is once again. [ATTACH]48691[/ATTACH]

It's true that the symbols of the components are made up by TE but maybe on the board they are correct.

Mark
 
nickb 4/30/2018 4:27 AM
It uses these modules [ATTACH]48692[/ATTACH]
 
MarkusBass 4/30/2018 5:11 AM
Which maybe purchased and simply replaced: 600W Amplifier Products ? Or sent to them to be fixed.
 
Roberto 4/30/2018 5:36 AM
Im in love guys. Thank you very much! I will keep you updated both for the ETS and ICE solutions.
 
J M Fahey 4/30/2018 6:25 AM
Quote Originally Posted by MarkusBass View Post
That's strange because I see the power amp and the power supply schematic in the download. Maybe a processor board that controls all the modules is missing but maybe they designed it without a processor.
Here it is once again. [ATTACH]48691[/ATTACH]

It's true that the symbols of the components are made up by TE but maybe on the board they are correct.

Mark
Weird, NO such .PDF in my Elektrotanya download as linked in post #2
Mind you, I opened all of them.
Weird.
 
MarkusBass 4/30/2018 7:17 AM
Quote Originally Posted by J M Fahey View Post
Weird, NO such .PDF in my Elektrotanya download as linked in post #2
Mind you, I opened all of them.
Weird.
It's because the file is in the Word (*.doc) format. Have you opened the the Word file?
 
Roberto 4/30/2018 7:37 AM
It is exactly this one: http://www.amplifier.co.uk/images/SDV1061-600_1_ETS.pdf
I've already dropped them an email.

Thank you very much guys!
 
MarkusBass 4/30/2018 7:46 AM
Did you look at the component I posted previously? It looks like a termistor in series with the power supply. If it's open, or incorrectly soldered, it may cause the problems you have. Can you make a better photo of the component?

Mark
 
Roberto 4/30/2018 7:56 AM
Quote Originally Posted by MarkusBass View Post
Did you look at the component I posted previously? It looks like a termistor in series with the power supply. If it's open, or incorrectly soldered, it may cause the problems you have. Can you make a better photo of the component?

Mark
Thanks Mark, unfortunately I will have access to the amp only next sunday, because I'll be out for work. I will try that too.

By now I've got some email exchange with the producers of the module: they forwarded me to the site shown here for the small module, but they have no SDV1061-600 stock, and they can produce them only if they get at least 100 units. And they do not repair it, even if it's their module being broken. I thought it was not even legal to do so, but it is.

No feedback from ICE yet.
 
Jazz P Bass 4/30/2018 10:12 AM
That SDV1061-600 is an evaluation board.

The item that ETS makes is the SDV1025-600.
It is a very small part of the Trace Elliot amplifier module itself.

http://music-electronics-forum.com/a...000-12-07.jpeg

See those 2 rows of little pins .
That is the module.
Tucked underneath.

[ATTACH]48694[/ATTACH]
 
Roberto 4/30/2018 12:16 PM
Thanks Jazz P Bass,

That was clear to me. I took three photo of it on the last triplet.
What I'm afraid of, is that the previous owner did some other damages on the board, so I would prefer to find the whole module. Let's see.

Thank you.
 
J M Fahey 4/30/2018 12:38 PM
Quote Originally Posted by MarkusBass View Post
It's because the file is in the Word (*.doc) format. Have you opened the the Word file?
No.
I opened all .pdf because thats the standard format for schematics, data, books, and a ton other things, can be zoomed to *any* size , and I mean ANY, you can take snapshots, make images automatically fit the page (for printing) or show stuff exact 100% size (real world reference), print it accurately real size on a sheet of paper (thats why its the preferred way to distribute iron-on PCB patterns , the works.
Other graphic file types are used, such as .gif, .png, .jpg (this one more suited to family holiday pictures than schematics) but none can even touch the precision of true .pdf vector graphics.
Of course, *some* .pdf are FAKE Pdf, just .pdf compressed bitmap image scans, not the same by a country mile.

Yes, I saw a couple "Office" type files in the Zip pack, but since two of them were .xls parts list files (which is sensible because it helps handling parts stock in a Factory environment ) and two were setup and adjustment instructions, essentially "text" where .doc files make sense, when I saw a third .doc file labelled *****schematics.doc, I reasonably assumed it was a list (and maybe description) of the mountain of .pdf files included : 34 !!!!! (thirty-four, not a typo)

After opening all 34 and not finding what I wanted, why on Earth would I open a presumed "file list" after I had opened all of them?

Oh well, further proof that Lawyers and Accountants (plus the random MBA) run the World and Techs and Engineers if travelling by Bus must seat in the back, behind the white line
 
J M Fahey 4/30/2018 1:01 PM
Quote Originally Posted by Jazz P Bass View Post
That SDV1061-600 is an evaluation board.

The item that ETS makes is the SDV1025-600.
It is a very small part of the Trace Elliot amplifier module itself.

http://music-electronics-forum.com/a...000-12-07.jpeg

See those 2 rows of little pins .
That is the module.
Tucked underneath.

[ATTACH]48694[/ATTACH]
I would phone ETS again to check if they have any spare SDV1025-600 left, and at what price.

Evaluation boards are very good but typically made only in small quantities, a Factory or independent designer might buy 1 or 2 to test whether the product mates with the rest of his product, design *his* own PCB covering his personal needs and then just purchase the SDV1025-600 in bulk.

Since this is a very outdated product, a transition type making it possible to retain most of the older product, including expensive and heavy iron power transformer, just saving on heatsinks (because board size is huge for what it does) , I very much doubt they are selling any now, except maybe a few as replacements for old amp servicing.

Revolutionary 20 yers ago, today its a dodo, replaced by similar power, smaller size, included SMPS modules, which to boot are cheaper.

Id ask for a spare SDV1025-600 module alone if available, if price is reasonable (by now they should have a fire sale on them) , take the chance and replace it on the moherboard.

If not available or very expensive or you simply do not trust the motherboard, Id just go for a new module, and somehow try to feed the preamp one way or the other.
In fact I would ditch even the obsolete working one , *and* the heavy toroid and fit a single ICE module there.

Your back will be grateful

Note: ICE are known for NOT catering to end users, I guessnthey have a minimum oder pack, say 50 or 100 units in a single carton, so they normally sell to Factories.

That said, I guess some people need, say, 30 of them, are forced to buy the, say, 50 unit minimum order, because now and then a few appear on EBay, from US sellers, at reasonable price (hey, they want to sell the overstock), so EBay is an option.
Of course , then theres none offered until somebody else does the same a couple months later.
 
g1 4/30/2018 1:27 PM
Quote Originally Posted by J M Fahey View Post
Id ask for a spare SDV1025-600 module alone if available, if price is reasonable (by now they should have a fire sale on them) , take the chance and replace it on the moherboard.
Not sure what price is reasonable, but profusion has them listed: SDV1025-600 - 600W Driver Board
 
Roberto 4/30/2018 1:41 PM
Thanks Juan Manuel and thanks g1.

Yes, Ive seen that link at around 75 plus shipping (so I guess around 90 ).

Juan Manuel, can you tell me how much can cost the ICE module on ebay? Im not in a hurry so I can wait, no problem.

90 isnt cheap for the small module itself, and it would be easy to fit a class D amp with SMPS onboard. Dig the big toroidal and add a small one for 12ax7s B+ and heaters (probably I have already one somewhere).

The main point, in that scenario, would be to keep the distinctive feature of this amp (even if I never used it): it can work stereo with its own stereo loop, or bridged.

Will the 1200AS2 do the job?
 
MarkusBass 5/1/2018 12:41 AM
Quote Originally Posted by Roberto View Post
90 isnt cheap for the small module itself
I'm surprised that you think that 90 isn't cheap. This amp is worth about 500 . Newer amps with similar power cost 1000 , or more.
When I fix amps the first rule is to bring it to the state as it was when it left the factory. Then, you may think about possible modifications.
The ICE modules are extremely difficult to buy and they cost about 200 -250 . You would need two of them. And this would be crazy to pay 500 to fix an amp that is worth 500
I'm not sure how reliable athe the original modules but I would go for the original. Otherwise, you would pay 400-500 (and you would need to work for free).

Mark
 
Roberto 5/1/2018 6:29 AM
Quote Originally Posted by MarkusBass View Post
I'm surprised that you think that 90 isn't cheap. This amp is worth about 500 . Newer amps with similar power cost 1000 , or more.
I understand your point, but we are talking about a small part of one of the two the power amps. No power supply, no output filters, nothing but the driver and the power mosfets for 600 W mono. Compared to 250 for a ICE stereo power amp capable of 1200 W including SMPS it's absolutely expensive!

Quote Originally Posted by MarkusBass View Post
The ICE modules are extremely difficult to buy and they cost about 200 -250 . You would need two of them. And this would be crazy to pay 500 to fix an amp that is worth 500
I'm not sure it will be needed to have two. Some of them I've seen that are capable of working stereo or bridged mono. If it could be the case for the 1200AS2 as well, I would be done with one ICE module only.

I'm waiting their reply on that.
 
Jazz P Bass 5/1/2018 10:04 AM
https://icepower.dk/products/amplifi...les/as-series/
 
nickb 5/1/2018 10:40 AM
Maybe the pics don't show the inflicted damage but that module looks repairable to me. Maybe even the AC018 module just needs the FETS replaced. I'd start by checking all the power rails on the board including the switching regulator. Next I'd look at the output prior to the filters to see if there is any activity. If nothing I'd check the shutdown signal on pin 17. Then, having found those to be OK I's unsolder the module and test the FETS. If it's a dead end at least you can go ahead with the module replacement or wholesale PCB replacement knowing you've given it a decent shot.
 
Roberto 5/1/2018 12:30 PM
Thanks Jazz P Bass!
 
Roberto 5/1/2018 12:39 PM
Thanks nickb, I will try the way you suggest before doing anything else.

I have to say that I'm also thinking to sell the good module (I've asked some repair centers and one of them asked me if I want to sell the good one), and buy something like this one: IRS2092 Stereo Amplifier | Connex Electronic (or better, just to guve an idea) adding few more bucks.
 
Jazz P Bass 5/1/2018 4:20 PM
Why do you not simply run the amp with one module?

How loud do you want it?
 
glebert 5/1/2018 6:10 PM
Quote Originally Posted by Roberto View Post
Thanks nickb, I will try the way you suggest before doing anything else.

I have to say that I'm also thinking to sell the good module (I've asked some repair centers and one of them asked me if I want to sell the good one), and buy something like this one: IRS2092 Stereo Amplifier | Connex Electronic (or better, just to guve an idea) adding few more bucks.
Have you checked out the class D boards on Ebay? You can get a 500W module for $20. Just search for IRS2092.
 
The Dude 5/1/2018 6:32 PM
I used one of the IRS modules in an Acoustic amp. I couldn't find an STK for it that wasn't fake. It worked well- actually better than originally designed. And, the price is right!
 
Roberto 5/1/2018 6:32 PM
Quote Originally Posted by Jazz P Bass View Post
Why do you not simply run the amp with one module?
How loud do you want it?
It's not a matter of being loud, but to restore the original features of the amp.
For my personal use and to sell it in the future.
 
Roberto 5/1/2018 6:40 PM
Quote Originally Posted by glebert View Post
Have you checked out the class D boards on Ebay? You can get a 500W module for $20. Just search for IRS2092.
Like those? www.ebay.it/itm/192155407840
Are they reliable for this purpose (adding a bridge rectifier with enough filtering) running two modules as stereo or together bridged?
 
Roberto 5/1/2018 6:48 PM
Quote Originally Posted by The Dude View Post
I used one of the IRS modules in an Acoustic amp. I couldn't find an STK for it that wasn't fake. It worked well- actually better than originally designed. And, the price is right!
Thanks The Dude, if you confirm they are working properly even if so cheap, I can buy two of them while trying to repair the original blown module.
 
The Dude 5/1/2018 6:51 PM
Here's a thread detailing my experience.

http://music-electronics-forum.com/t45099/

Post #30 links the module I bought. There are different ones. You'll need to pay attention to mono/stereo, power output, power supply requirements, etc. Ebay is full of them. I have no doubt you can find one that would work.
 
J M Fahey 5/1/2018 9:56 PM
Quote Originally Posted by Roberto View Post
It's not a matter of being loud, but to restore the original features of the amp.
What for? Is this a collector amp or something? Did Jimi Hendrix use it in the last shopw of his life?
For my personal use
Then I guess a 500W mono Bass amplifier is enough
and to sell it in the future.
Will you spend $250 to $500 on a 20 year old amplifier with no particular Mojo attached which *might* sell for $500 if you are licky?

Just being the Devils advocate, nothing personal.

You might also spend the $90 on the replacement power block, ... anything further is burning money with a match.
 
glebert 5/1/2018 10:27 PM
Quote Originally Posted by Roberto View Post
Like those? www.ebay.it/itm/192155407840
Are they reliable for this purpose (adding a bridge rectifier with enough filtering) running two modules as stereo or together bridged?
I haven't even gotten around to installing any of the modules I've bought (though I have amps that need them), but personally I would go with the biamp/stereo configuration and not try to bridge them. Who needs 1000W into one cabinet?
 
Roberto 5/2/2018 12:44 AM
Quote Originally Posted by glebert View Post
I haven't even gotten around to installing any of the modules I've bought (though I have amps that need them), but personally I would go with the biamp/stereo configuration and not try to bridge them. Who needs 1000W into one cabinet?
No one, but this is the way this amp came out of the factory, I would like to keep it. In case of resell, if it's a matter of spending 30 euros for these ebay cheap modules that The Dude testes, it could be a a plus.
 
Roberto 5/2/2018 12:47 AM
Quote Originally Posted by J M Fahey View Post
Just being the Devils advocate, nothing personal.
You might also spend the $90 on the replacement power block, ... anything further is burning money with a match.
I agree, that's why I told 90 € wasn't so cheap as a part of one of the two power amp modules.
The Dude has proposed some cheaper solutions (around one third of it for 2 modules), using the big toroid already installed (plus a separate rectifier and capacitors board).

EDIT: In Italy those amps are sold, used, at around 800-900 €.
 
g1 5/2/2018 12:56 PM
Quote Originally Posted by Roberto View Post
EDIT: In Italy those amps are sold, used, at around 800-900 €.
Then if you sell that used module, you should get quite a bit for it.
 
glebert 5/2/2018 2:39 PM
Quote Originally Posted by Roberto View Post
No one, but this is the way this amp came out of the factory, I would like to keep it. In case of resell, if it's a matter of spending 30 euros for these ebay cheap modules that The Dude testes, it could be a a plus.
If you plan on reselling one thing you'd better do is actually test it at full power with minimum load, which is not easy to do with a 1000 watt amp. I've got an Ampeg SVT 7 Pro that I have sold 3 times because it keeps having issues.
 
Roberto 5/3/2018 8:16 AM
Quote Originally Posted by g1 View Post
Then if you sell that used module, you should get quite a bit for it.
Probably it should be like that, I've not investigated yet.
 
Roberto 5/3/2018 8:29 AM
Quote Originally Posted by glebert View Post
If you plan on reselling one thing you'd better do is actually test it at full power with minimum load, which is not easy to do with a 1000 watt amp.
Thanks for the tip glebert. Anyone uses electrical heaters to do such kind of tests? Something like three 2kW heaters in parallel (on this side of the pond we run at 230VAC) that should make something around 8 Ohm load (how hot the heaters run usually? in other words, will the resistance be much lower when run cold/warm?).
 
glebert 5/3/2018 8:53 AM
Quote Originally Posted by Roberto View Post
Thanks for the tip glebert. Anyone uses electrical heaters to do such kind of tests? Something like three 2kW heaters in parallel (on this side of the pond we run at 230VAC) that should make something around 8 Ohm load (how hot the heaters run usually? in other words, will the resistance be much lower when run cold/warm?).
I do something like this, ours are usually rated for 1500W on 120VAC, which should be 8 ohm, but I have found the resistance at cold is more than expected (10 ohms), implying that they either don't actually run at the 1500 watts or perhaps the resistance drops when hot (but that would be opposite of normal physics of a metallic conductor). Often there are two coils in the heater (one for half power, both for full power) so you have to run those coils in parallel to get down close to 8 ohms.

Oh, and while resistive load testing is good, some high power testing through a cab is important too. My cursed SVT 7 Pro's current problem only happens during vibration/shock (like what happens when sitting on a bass cab with 1000 watts coming out), and does not show up during a resistive test.
 
Roberto 5/4/2018 6:20 AM
Quote Originally Posted by glebert View Post
Oh, and while resistive load testing is good, some high power testing through a cab is important too. My cursed SVT 7 Pro's current problem only happens during vibration/shock (like what happens when sitting on a bass cab with 1000 watts coming out), and does not show up during a resistive test.
Thank for this detail! May I know what was the issue, at the end? One of the broken amps that I've bought had similar issues and it was just a cold welding that broke down with the years. Half an hour and few cents to bring it back to life.
 
glebert 5/4/2018 9:01 AM
Quote Originally Posted by Roberto View Post
Thank for this detail! May I know what was the issue, at the end? One of the broken amps that I've bought had similar issues and it was just a cold welding that broke down with the years. Half an hour and few cents to bring it back to life.
http://music-electronics-forum.com/t46071/

Haven't gotten around to working on it yet, and I will admit it is mostly reluctance to even touch an iron to surface mount components, which is dumb.
 
J M Fahey 5/4/2018 7:18 PM
Electrical water heaters are the best load resistor available over the counter. Run them under water, of course. Resistance variation is actually quite small, since you are not letting them run red or white hot, as in a lamp or an oven/toaster/etc. situation; boiling water is actuall real close to ambient temperature, compared to those other duties. 10 ohms is actually real close to 8 ohms, if we are testing amp overheating, "burn in", etc. its close enough. And in fact 8 ohm real world speakers are above 10 ohms over [B]most [/B]of their range, except at a midrange section between 200 and 350 or 400 Hz, just look at this graph: 8 ohm red line; 10 ohm blue line: [ATTACH=CONFIG]48767[/ATTACH]
 
Roberto 5/5/2018 1:10 AM
Thanks again glebert and Juan Manuel. So the easiest option is to put two water heating of 3 kW each in parallel, immersed in water and connected to a speakon connector. Considering 1 kW ouput power, and a reasonable 2 hours of continuous full power test, at least 25 liters of water are needed to avoid going into ebullition: 1 kW are 860 kCal/h 860 kCal/h / 25 liters = 34.4 K/h So we wont go into ebullition even if the starting water temperature is 30 Celsius degrees, and considering no thermal dispersion into the ambient. Noting against ebullition, except it can sprout water on the test bench and vapour in the air that can condensate on colder surfaces. Do you use something similar Juan?
 
Jazz P Bass 5/5/2018 12:02 PM
"Reasonable 2 hours continuous output power test?" Say what??? Believe it or not, for test purposes, you do not need to beat the piss out of the amp like that for that length of time. 50% power output is probably harder on the amp. Unless maybe you are doing a current limit test ala QSC.
 
Roberto 5/5/2018 12:36 PM
Perfect, so 600 W total will be enough, and water can go down to 15 liters: even better to be moved.
 
J M Fahey 5/6/2018 5:51 PM
FWIW I use sections of standard "spring" type heating elements, eyelet/riveted to strips of Micanite (remanufactured Mica sheet) , which allows me to get *exact* resistance value needed, then drop such load resistors inside a bucket of water 1 or 2 meters away from bench, so even if it boils, no big problem.
B esides being dirt cheap, they allow me to get off resistance vaalues at will, such as 6.6 o 5.5 ohm, which are typical real worldspeaker DC resistance values.
Excellent to test protection circuits .
 
Roberto 5/14/2018 4:09 AM
I'm just back home from a long trip, while I've found some solutions:

Substitute the modules at 60 for both, and sell the working one:
2x https://www.ebay.it/itm/121370148870

Substitute the big toroid and final modules with those (small toroidal for the 12AX7s) at 120 for both modules and resell the working module plus the toroid:
2x https://www.ebay.it/itm/172546989166
2x https://www.ebay.it/itm/282836152610
https://www.tube-town.net/ttstore/Tr...7VA::5391.html


Substitute the big toroid and final modules with those (small toroidal for the 12AX7s) at 115 and resell the working module plus the toroid:
1x https://www.ebay.it/itm/142742467613
2x https://www.ebay.it/itm/282836152610
https://www.tube-town.net/ttstore/Tr...7VA::5391.html
 
Roberto 5/14/2018 10:50 AM
They replied to me today: they do not sell directly, and the AS series cannot be sold in small numbers even from their partner site.
 
Roberto 5/16/2018 3:46 AM
I've found a cheaper option to keep the toroidal and have the mono and stereo capabilities:
Run the two windings of the PT in parallel to this bridge rectifier (GBPC50: 1000V 50A 1,1V drop), that costs 4 :
https://docs-emea.rs-online.com/webd...6b80dadbc2.pdf

Then this module that costs 100 :
https://www.ebay.it/itm/142730977129
Running stereo at 500 + 500 W on 4 + 4 Ohm or mono bridged at 1000 W on 8 Ohm.
Two fans and an air filter will be added as well.

And of course resell the two modules.
 
glebert 5/16/2018 10:13 AM
Note you also need a low voltage (6-12V) AC signal to that power module as well.
 
Roberto 5/16/2018 10:21 AM
Thank you glebert, yes they told me 12-0-12 Vac or 15-0-15 Vdc.
I'm waiting a reply about the needed current (that I think would be low), in order to see if I can use the PSU already present in the preamp (15-0-15 Vdc).
 
Roberto 5/18/2018 4:20 PM
Ok, I finally came out with the following solution:

1x https://www.ebay.it/itm/142742467613 @ 61 € shipped
1000 W power supply with custom:
+-70 VDC for the power amp
+-15 VDC 500 mA for the preamp and the heaters of the preamp tubes (in series with 33 Ohm, so something less than 150 mA for them)
+12 VDC 500 mA for the fans

1x https://www.ebay.it/itm/172833474016 @ 67 € shipped
1000 Wrms @ 8 Ohm power amp (if bridged, capable to run stereo as well as the original amp)
Needs +-70 VDC plus +-15 VDC

1x https://www.ebay.it/itm/192074192680 @ 20 € shipped
Toroidal transformer 50 VA
Pri 0-230 VAC
Sec 0-200-260-290 VAC 180 mA (one secondary with three taps to try three different B+ for the 12ax7s)

Total will be 148 €, and I'll have the original toroid and two modules (one working, one not) to sell, plus I'll save 22 kg of weight on the amp.

Do you guys see something technically wrong in this solution?
Thank you for your feedback.
 
Roberto 6/5/2018 8:59 AM
An update on the topic: as a load to test the power amp I've found this water heater:
https://www.ebay.it/itm/361962587631

It has three elements in parallel, 2 kW each at 230Vac, so that the three in parallel give 8,9 Ohm.
13 euros shipped.
 
nickb 6/5/2018 12:35 PM
It says it'd 380V so 380^2/6000 = 24 ohms. You need to buy three of them.

I saw these 220VAC 6KW ones. They would be 8 ohms.
 
Roberto 6/5/2018 2:45 PM
My interpretation of its declaration is different, but I've asked to the supplier to better specify.

380 V is sqrt(3) * 220 V, so the old EU three phase standard voltage.
This should be confirmed from the fact that there are three units in parallel (one for each phase).
This would mean three resistor in parallel of 2 kW each, means three resistors of 26.45 Ohm each (because between each phase and neutral there are 230 V), so 8.82 Ohm when connected in parallel.
 
Roberto 6/8/2018 5:51 AM
Now I know how they are connected usually.

[ATTACH=CONFIG]49181[/ATTACH]
 
nickb 6/9/2018 2:07 AM
Ah ha!. Well that's worth knowing.Thanks for the info.
 
Roberto 6/9/2018 3:36 AM
Thanks to you for letting me think more about it.
Even the seller was not able to answer me, I've used google images to find another seller's instructions.
I'll go with this one: https://www.ebay.it/itm/401314483971
 
nickb 6/9/2018 4:37 AM
I think they are the same but that one is just strapped for 220V.
 
Roberto 6/9/2018 5:09 AM
Ouch! The one you linked doesnt ship to Italy. I will search more. Thanks!
 
J M Fahey 6/9/2018 6:46 AM
Why would you buy water heater resistors outside Italy, a *most* Industrialized Country, is beyond me

Id check one of these:

http://www.thermowatt.com/it/categor...nze-scaldacqua

https://www.riscaldatori-elettrici.i...sione-liquidi/

https://www.riscaldatori-elettrici.i...er-immersione/

http://www.tre-c.it/everwatt/prodott...er-immersione/

http://www.mdrmarca.it/prodotti/prod...che-per-acqua/

of course, you ask for the raw element, no thermostat.
 
Roberto 6/9/2018 7:05 AM
Quote Originally Posted by J M Fahey View Post
a *most* Industrialized Country
We could start a bi-logue (does this exists? ) about how the industry delocalization of the last decades, following the cheapest manpower, lead to loss of know-how in the G7, but I'll simply answer to your question: I'm a Mechatronic Engineer with a specialisation in food and beverage processing and a passion for electronics. I'll use this heater to test this power amp and most probably nothing more in the rest of my life. In Italy the standard contract for each apartment is 3 kW, and the standard heater is around 2 kW (to permit to use something else while heating the water). So I need at least three. Consider then that I would have to buy spare parts, that usually are sold with at least a 300% margin on them. This make the price of the final dummy load something like 10 times the cheap chinese one, and I'm not so sure it wouldn't be chinese and resold. So 15 euros are ok to test once the power amp, while 150 euros are not (it would cost more than the power amp to test).

That's all.
 
Roberto 6/18/2018 5:47 AM
Thanks for the update links Juan Manuel,

in the meanwhile I've receipt the power amp (I've already have the caps, so I bought it without them) and the toroidal HV transformer (20 euros each from a company close to me) with three taps on the secondary: 200-260-290 Vac (to be able to choose different working points of the preamp). I'm waiting for the power supply then I'll assemble everything.
Here comes the photos.

[ATTACH=CONFIG]49361[/ATTACH]

[ATTACH=CONFIG]49362[/ATTACH]
 
MarkusBass 6/18/2018 6:40 AM
I use such resistors (4 connected in parallel and attached to a big heatsink): http://it.farnell.com/welwyn/wh100-1...15r/dp/1768209
 
Roberto 6/18/2018 6:43 AM
Thanks Markus,

unfortunately for this PA they would not be enough, and to buold a load with those I would pay 8 times more.
Those are perfect to dissipate power on guitar dummy loads.
 
MarkusBass 6/18/2018 8:35 AM
I'm sorry. I haven't noticed how much power you need to dissipate.
 
Roberto 6/22/2018 1:11 AM
First step: weight loss.

[ATTACH=CONFIG]49441[/ATTACH]

[ATTACH=CONFIG]49443[/ATTACH]

[ATTACH=CONFIG]49442[/ATTACH]
 
Roberto 6/24/2018 4:53 PM
I'm sure that in an amp in big series there's a reason, but why this part of the amp is supplied at 14V?
Thanks

[ATTACH=CONFIG]49477[/ATTACH]
[ATTACH=CONFIG]49478[/ATTACH]
 
Roberto 7/1/2018 6:30 AM
Is anyone aware of the reasons why I can't use two diodes in series (or even tapping it from the +15V) to drop 1,2V instead of the 22 Ohm resistor and the 47 microfarad capacitor?
 
Tom Phillips 7/1/2018 9:30 AM
Yes. The resistor and capacitor form a decoupling Network between the two sections of the circuitry. The diodes would only drop the voltage.
 
Jazz P Bass 7/1/2018 10:03 AM
Quote Originally Posted by Roberto View Post
I'm sure that in an amp in big series there's a reason, but why this part of the amp is supplied at 14V?
Thanks

[ATTACH=CONFIG]49477[/ATTACH]
[ATTACH=CONFIG]49478[/ATTACH]
The +14Vdc is the supply for the LEDs.
The opamps 'sink' the voltage to turn the LEDs on.
 
Roberto 7/1/2018 9:04 PM
Thanks Tom and Jazz.

Can you please explain me why is needed to supply the leds with a decoupled supply?

Just some noise while turning on and off the leds, or it is because when leds will turn on, the current increases (almost doubles) and the reference for the red light come sooner? Something to make the user not to overload the power amp for long periods, but lower the level even more than needed (the temporary lower voltage reference of the comparators) then back to normality.
 
Roberto 7/9/2018 1:30 AM
One more step:

[ATTACH=CONFIG]49656[/ATTACH]
 
Roberto 7/25/2018 6:06 AM
Do you guys suggest to add "sponges" before the fans, to filter out the dust from the cooling air?
I see pros, main one is of course is avoiding dust inside the rack, and cons, main one is that while the filter is clogging, the fans will move its working point towards the left of the curve, reducing the airflow.
 
Jazz P Bass 7/25/2018 10:36 AM
If you do keep the filters clean, it is a win win.
 
Leo_Gnardo 7/25/2018 11:14 AM
Quote Originally Posted by Roberto View Post
Do you guys suggest to add "sponges" before the fans, to filter out the dust from the cooling air?
Fan setups that have these kinds of filter, the filter material looks to me an awful lot like a scotchbrite pad. There are several varieties of scotchbrite. If I were to add/replace this kind of filter I'd pick a likely looking scotchbrite or similar scrub pad, cut it to size, install it and smile. When it starts looking loaded with dust simply remove, wash out with detergent & water, rinse, air dry & reinstall.
 
Roberto 7/25/2018 7:43 PM
Thanks guys.
 
The Dude 7/25/2018 7:53 PM
I buy filter material for dehumidifiers. You can get it in large rolls at most hardware stores. Just cut off the size you need.
 
Roberto 7/26/2018 1:23 PM
Thanks The Dude!