For the LF amp PS you could use as much capacitance you want , if you want to have 22000uf, then just go for it, about the capacitors from the MF and Hf amp ps, I whould personally replace those with 6800uF and 4700uF, but it is up to you.
I would definitely replace C636, c655(same value or larger), c606( This one I would replace this with a larger value, more than 3300uF).
And I would probably take a look at all of those 1uf caps in the signal path, replace them with audio electrolytics (es, kz, silmicII etc) or even with mkt(wima mks2 etc). Have fun
I would definitely replace C636, c655(same value or larger), c606( This one I would replace this with a larger value, more than 3300uF).
And I would probably take a look at all of those 1uf caps in the signal path, replace them with audio electrolytics (es, kz, silmicII etc) or even with mkt(wima mks2 etc). Have fun
Thanks you johnego .
If you need more information about schematic and service manual let me know .
I tried to compare the sound of these active speakers Braun LV1020 with expensive brands in High End salons not hi-fi , the modernist high class lost in realism, airiness, and the believability of the instruments. I am very pleased with these active speakers, listening to music from the DAC Antelope Zadiak.
I am want make this system sounding maximum better the most out of the already above the decent sound of this system.
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On schematic on wrong connection (LF amp lower on schematic) R615 connect T605 emitter , this is wrong , look other amps. I'm check board LF amp no connection .
Thanks for the advice with good resistors and many more . I'm new to this hobby and any advice for me is a big help.
Can you tell me more about this ? Thanks
Wow thanks , I w'll try .
My oscilloscope is my ears, I want to bring the sound of instruments closer to natural sound even more than it is.
I will order parts and experiment all that I have been advised here. . A lot of thanks .
Honestly, I removed the resistance of the R614 on the low-frequency amplifier which is at the very bottom of the diagram, the bass opened up became even more natural, vibrational. By the word bass, I mean not low frequencies, but realistic sound of low registers of instruments. In the circuit, there was only feedback on the low-frequency amplifier.
This is gorges sounding active speaker with simple amplifiers .
One question:
The native transformer produces 48V AC for 2 amps , after the bridge 5000uf, the voltage after the capacitor is obtained according to the 59V scheme, in fact, I measured 62V DC. If I put for example 22000uf capacitor instead 5000 uf whether the voltage rises?
At the low-frequency amplifier, I will order a separate transformer, I can buy not 48v but 44 volts, if this is critical ?
The native transformer produces 48V AC for 2 amps , after the bridge 5000uf, the voltage after the capacitor is obtained according to the 59V scheme, in fact, I measured 62V DC. If I put for example 22000uf capacitor instead 5000 uf whether the voltage rises?
At the low-frequency amplifier, I will order a separate transformer, I can buy not 48v but 44 volts, if this is critical ?
thx i'll do that if i need info on other things
isn't it hard to compare apple to orange? subjective taste may be at play. The quasi amp, like Naim, might have unique trait, but may be not as special as Naim looking from the chosen transistor.
Then you need to improve the power supply. its a critical part of an amplifier. and you have many signal coupling caps. the xover supply is 36v, filtered by an RC from raw 59v. Replacing with LM317 may be a good move.
no worry with circuit works.
for cap multiplier you can search the forum. it may be too much work for you but it depends on how far you will go in improving your system. the bootstrap cap is a cap connected with the output, going to the top transistor's base thru some R. theoretically the bigger the better but cap quality is important so the opposite might happen if bigger means using cheap cap.
All amps have the standard feedback, check R605. If you remove r614, you increase amplifier control over the woofer (most critical variable for amp quality imo) with the expense of increased distortion. But volume level will be increased too so check if your perception of improvement is not dominated by this.
why would you buy another transformer? It is not worth it.
The voltage does not rise because you replace a 5000uf cap with a 22000uf cap,
I would not buy an 22000uf/80V for this project , what I said it was that for LF power amp PS you could use as much capacitance ....I would use 10000uf/80v in this old amp...
Asuslover 
johnego
Each amplifier will have a separate power, as a reward for a good sound, let them eat it.
Each amplifier will have its own bridge and its own capacitor. According to the measurements, it will probably not make any difference to what it was, but it will probably be better by the sound. The main thing is not to spoil.
I will deal with experiments on the second set of amplifiers.
johnego
Each amplifier will have a separate power, as a reward for a good sound, let them eat it.
Each amplifier will have its own bridge and its own capacitor. According to the measurements, it will probably not make any difference to what it was, but it will probably be better by the sound. The main thing is not to spoil.
I will deal with experiments on the second set of amplifiers.
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less 6v, i.e. (48-44)*1.414, is not critical i guess. slightly less max power.
i agree with Sumotan, 22000uf might kill the sound. what cap do you have in mind? unfortunately i have no experience with the vishay. safer to parallel smaller caps. 2x4700uf looks good enough. 4700uf is a value where cheap caps still perform.
22000uf took a maxim as an example, the more 22Kuf does not fit inside . On this and asked how it would be better.
I read on the forum here , one capacitor sings better than several of the same together.
The exception is the Panasonic PC , again this is not my experience. post#14 Best capacitors for power supplies update
Good people you do not represent how much you helped me. Thank you so much for your time. I now have a basis for what to do.
The bigger the capacitance, the more impossible to parallel, unless with lower value. And comparison must be apple to apple. pana FC/FM is very low esr. many regulators hate to drive them. Yours is raw PS, Pana is ok. its hard to find bigger than 2200uf pana fc. if you can buy 10000uf pana fc, that is of course better. cheaper too.
BTW, if you have or need more caps but paralleling will kill the sound, you can use different supply for left or right (i'm not aware of the effect of single vs dual on soundstage tho). but any diode will benefit from current reduction due to dual supply.
it was published in the 1980 AUDIO magazine, that article was about adding extra capacitance in the psu....that must have started the race for huge filtering in psu's, i still have the magazine article and i suppose i can post a snippet of it if only to show it exist and then you can chase it yourself to know what Walter Jung wrote in the article...
about the same time, another collaborative article about Picking Caps appeared in the AUDIO magazine about the same time...Picking Capacitors, Part 1 - Walt Jung
yes you can buy lower at 44 volts and you are not going to miss a lot...
48 volts ac when delivering 2 amperes load current....
simply meant that unloaded voltage is higher than 48 volts, this is to be expected.....laws of physics dictates this....
everything has a reference, i am sure those voltages were quoted with a certain line voyage, say 120 vac, then when you have a line voltage other than that expect readings to be different...
rod elliot wrote a fine article about power supplies...Power Supply for Power Amplifiers
Hi John,
-Chris
Well, it is a power diamond buffer and tends to be quite fast. The Nakamichi 620 is the same basic design and sounds similar. Done correctly, these are really good sounding units. Have you ever heard a stock one? The Marantz 170DC sounds similar but not as good due to the extra circuitry in the 300DC. At any rate, you have to hear one of these in order to make a judgement. Remember that I have modified this amplifier so that the highs and mids are free from a slight "grainy" sound the stock units can have. The amplifiers that sound better so far are the new Bryston 4B cubed and the Marantz 500 after I've rebuilt it. I've done a few and would love one for myself. Not sure which sounds better, the 4B or the 500. Again, you have to hear the real amplifier, not a clone.
That can easily sound a lot better than any system using passive crossovers. I'm currently working with someone on active systems. One using Marantz improved 2325 amp sections, and another using Marantz 300DC amps, all modified. I do have one customer with a bi-amped (Active crossover) using a pair of modified Marantz 170DC amplifiers on custom speakers (not my design). My bench amplifier is a newly acquired Marantz 170DC (modified) and a Yamaha C-50 preamplifier I had rebuilt. The original bench amplifier was a Marantz 1180DC that acquired a hum on the pre output due to an ill behaved amplifier that fed power back from the RCA inputs! Weird failure mode. The 1180DC will be repaired and either be sold or live live as a monster computer sound system.
-Chris
I can't remember Marantz numbering system (I don't use the amps, only occasionally when the moon is on the right latitude). I have four Marantz but I can't remember the models. I think SC-7 whatever.
What do you think of the dual JFET used in Marantz amps, are they any good compared to the classic J109/K389 (I believe you have measured them)?
Marantz and Accuphase are probably the early adopter of current feedback and fast amplifiers, but they are visually not symmetrical to be attractive.
Thanks Chris, I will study these two amps later. I have heard 4B in a demo and I liked it (the whole setup of course) a lot. But many audiophiles think this amp is nothing special.
Regarding active system, what do you think of the simple circuit of Braun LV1020 active system posted here? I will at least build the quasi amplifier part to find out.
Hi John,
The preamp numbering doesn't follow any plan I'm aware of. The amplifier numbering normally indicates the total power, or the power per channel. In the case of the 300DC, it is 150 watts into 8 ohms, and they are direct coupled if you switch out the coupling capacitor. This amplifier isn't very large, but it weighs 60 pounds.
The normal Marantz practice is to derate the power output by about 30%. So a 250 watt output normally will measure 330 watts into 8 ohms on the bench. The 500 delivers 500 watts per channel into 4 ohms. I still can't get over the fact that the amplifier does this while sounding detailed and airy in the mid & highs, and really solid in the bass department.
If someone who knows what they are doing rebuilds these amplifiers while matching the transistors closely, and also replaces certain capacitors, you would use the amplifiers. The tube amp lovers in my circle really like the Marantz amps I have done. They hated the 300DC at first, then I modified it. Their opinions reversed and some have purchased similar amplifiers and had me work on them. They aren't complaining at all.
As for the 4B cubed, I really liked it. This means that Bryston finally got it right. I could live with one happily from what I heard.
The preamp numbering doesn't follow any plan I'm aware of. The amplifier numbering normally indicates the total power, or the power per channel. In the case of the 300DC, it is 150 watts into 8 ohms, and they are direct coupled if you switch out the coupling capacitor. This amplifier isn't very large, but it weighs 60 pounds.
The normal Marantz practice is to derate the power output by about 30%. So a 250 watt output normally will measure 330 watts into 8 ohms on the bench. The 500 delivers 500 watts per channel into 4 ohms. I still can't get over the fact that the amplifier does this while sounding detailed and airy in the mid & highs, and really solid in the bass department.
If someone who knows what they are doing rebuilds these amplifiers while matching the transistors closely, and also replaces certain capacitors, you would use the amplifiers. The tube amp lovers in my circle really like the Marantz amps I have done. They hated the 300DC at first, then I modified it. Their opinions reversed and some have purchased similar amplifiers and had me work on them. They aren't complaining at all.
As for the 4B cubed, I really liked it. This means that Bryston finally got it right. I could live with one happily from what I heard.
As far as I remember 4B also has comparably non-standard complex schematic.
Hi John,
The 500 isn't that complicated. It breaks down into subassemblies that are fairly well known things. What the schematic didn't show was that the power transformer is designed for 2.2 Kw. It has a soft start circuit that limits the inrush to about 5 amperes. The DC power is delivered by buss bars, not wire.
It's the finesse this amp has in spite of it's high power. If you ever get a chance, have a listen to one properly working in stock form. It only gets better from there.
-Chris
The 500 isn't that complicated. It breaks down into subassemblies that are fairly well known things. What the schematic didn't show was that the power transformer is designed for 2.2 Kw. It has a soft start circuit that limits the inrush to about 5 amperes. The DC power is delivered by buss bars, not wire.
It's the finesse this amp has in spite of it's high power. If you ever get a chance, have a listen to one properly working in stock form. It only gets better from there.
-Chris
It is too 'complicated' for me. May be because I have no needs and interest with such a higher power amplifiers so I cannot see the needs why it has to be complicated. My constant current source has much more parts but I don't see it as more complicated.
I re-reading everything that wrote everybody.
Hi Chris, I can find a three amp tube circuit, my Russian friend gave me a link from a Russian site with a description of tube amplifiers with a built-in crossover . Anyone interested can share. I just need to search through a bunch of posts to find a link. If you or anyone interested, I will find.
Thank you, Tony . I read . very interesting. I liked grounding with diodes id .
I have a question about a transformer.
1 Is it necessary to add a separate transformer for the low-frequency amplifier, which consumes more power than others amps ?
Option 2 . You can order (????) powerful transformer in exchange for a native one with power to each amplifiers .
Option 3, use the native transformer, but as in the article on the link that you gave, add a bridge and a capacitor by dividing the power between the low and midrange amplifiers.
Maybe there are some other options?
I want make best this genius active speakers .
Where I can get right one LM317 board for my amp ?
And , Braun has to different schematic by serial #11500 this is first models ,(what now play in my house ) and letter was change crossover serial , amps all the same , serial #11501 and up , which I want rebuild ( my second set amps what I want rebuild ) different xover supply .
And what need to do with this ?
Can i get one from somebody or buy on ebay this magic board or somewhere good one for my amps ?
with transformers used in amplifier psu's the VA rating is the thing...say your amp delivered 100 watts per channel into 8 ohm speakers, then at the very least you should get a traffo that can deliver 200 watts, if you want to run your amp thru FTC testing then anther 200 watts or make your traffo good for 400 watts, but if just listening to music, then 200 is watts is minimum...
i once asked a guru in this forum about transformer size, he came back with this advise, "get the biggest that will fit inside of your box..."
sine waves have way more energy content than music, as much as 10 to 1...so the traffo in your amp can scale as such....
what is the right answer? i really do not know, but the truth must be somewhere in between....
if i were making my own amp, i will know, but it is not really up to me to tell people what to do....
Thanks Tony. I'm understand .
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It turns out to buy capacitors is not so easy.
Anybody !!!
I'm stock with capacitors because NOT in STOCK . (DigiKey Electronics - Electronic Components Distributor , Mouser Electronics - Electronic Components Distributor) nothing out of stock .
People where you buy parts ?
I'm looking for orange EPCOP , WHERE , why sale this parts ????
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It turns out to buy capacitors is not so easy.
Anybody !!!
I'm stock with capacitors because NOT in STOCK . (DigiKey Electronics - Electronic Components Distributor , Mouser Electronics - Electronic Components Distributor) nothing out of stock .
People where you buy parts ?
I'm looking for orange EPCOP , WHERE , why sale this parts ????
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