Hi Salas,
I am getting 21v AC from my 18-0-18v R transformer, so I may have to use the spare 15v one I have. There is no heat generated from the IRFP140 and IRFP9140s, the 10R resistors get slightly warm as do the MUR diodes. I measured 1.3v drop across the 10R resistors, so I have 130ma in each half of the PS = 260ma total - slightly hot-rodded?
The regulated DC is 10.2 and 9.5v - need to verify this as I only checked briefly - will this need attention?
The power supply I have knocked together to feed 8 v into the switched volume controller board, which has its own 5v regulator, is generating more heat than the "slightly hot-rodded" DCB1. tapped into the unregulated DC, I have 2 parallel 10w 47ohm resistors feeding a 7812 reg and then a 22ohm resistor in series. Is there a better way of doing this? If I am going to generate heat, let it be from super nitro, hot-rodding the well designed B1 and not my amateur attempts to power this low current control pcb. I know it will get a bit better with the 15v tranny, but even so, I would like to keep it as cool as possible. I am considering one of those DC-DC integrated circuits, but want to avoid anything that could genarate any extra noise if at all possible.
Brad
Brad
I am getting 21v AC from my 18-0-18v R transformer, so I may have to use the spare 15v one I have. There is no heat generated from the IRFP140 and IRFP9140s, the 10R resistors get slightly warm as do the MUR diodes. I measured 1.3v drop across the 10R resistors, so I have 130ma in each half of the PS = 260ma total - slightly hot-rodded?
The regulated DC is 10.2 and 9.5v - need to verify this as I only checked briefly - will this need attention?
The power supply I have knocked together to feed 8 v into the switched volume controller board, which has its own 5v regulator, is generating more heat than the "slightly hot-rodded" DCB1. tapped into the unregulated DC, I have 2 parallel 10w 47ohm resistors feeding a 7812 reg and then a 22ohm resistor in series. Is there a better way of doing this? If I am going to generate heat, let it be from super nitro, hot-rodding the well designed B1 and not my amateur attempts to power this low current control pcb. I know it will get a bit better with the 15v tranny, but even so, I would like to keep it as cool as possible. I am considering one of those DC-DC integrated circuits, but want to avoid anything that could genarate any extra noise if at all possible.
Brad
Brad
I assume you are trying to lower the voltage going into the 5V regulator because it can't handle the higher voltage. I assume the unregulated voltage must be around 30VDC. If your volume control board is pulling a steady 150mA then your parallel 47R resistors are dropping around 3.5V, and the 22R about the same. So you are putting about 26V into the 7812, and then dropping it's output to about 8V. But the point is, you are dropping about 22V all together, and the current is 150mA, so that's something over 3W that needs to be dissipated somewhere; you're just spreading it over 4 devices. I would think 12V would be an OK input to the 5V regulator, so put your 47R resistors in series and drop the input to the 7812 to about 15V. The regulator will be warm, and so will the resistors. If the heat is too much then get rid of the 21V xformer, and maybe use a much lower voltage one to power the volume board. There is no magic way to dump that voltage without turning it into heat.
DCB1
Advice needed, again.
I've ordered LDR pot kit from Uriah. I'm looking for the best way to implement it in (before) my dcb1, as I don't want to do it twice. As I understand, I have these options:
1. LM317 regulator way, tapping voltage straight from DCB1.
2. Using spare DCB1 board as a shunt reg. only. (Do I need additional transformer in this case?)
3. +5V Salas Shunt reg. board and +/- PSU board as in Oliver's version.
My transformer is R-Core 50VA 2X15V, which if I remember correctly, actually gives near 2x18V.
Talking about the sound... After spending some time with TX2575, I love their sound so much that I've ordered a pair of TX2352. But there's still one thing, lack of expression in lower regions. It's not that it lacks just a little more punch for my taste, it's very recessed. I guess, the buffer is not there to blame and I look with suspicion towards my amp now. Dried caps? Something else?
In case of caps replacement, I would spend half of new amps budget replacing all (I have no means to detect a leaking cap, right?) of them. That being said, I accept new project suggestions for my new amp. Beware of even more noob questions coming your way!
But I promise to work on my technical knowledge, independently too.
P.S. There's a thing suggesting me it could be my worn out amp caps. A little, almost inaudible from listening position hum/buzz going from one channel, when there's nothing connected except speakers to the amp. Interconnects with or without passive pre or DCB1 give two channel hum/buzz. In a couple of days I will try adding CL60, but I doubt it's a grounding issue. Or could it be? My old soviet flat doesn't have a separate safety ground wire. As I understand there's only earth connected to neutral somewhere at a breaker pannel. And the whole house could be sharing it!
That complicates virtual grounding of my Quad 707 a bit, doesn't it?
Ok, mabe I'm asking too much attention now Thanks for all the help, anyway
Advice needed, again.
I've ordered LDR pot kit from Uriah. I'm looking for the best way to implement it in (before) my dcb1, as I don't want to do it twice. As I understand, I have these options:
1. LM317 regulator way, tapping voltage straight from DCB1.
2. Using spare DCB1 board as a shunt reg. only. (Do I need additional transformer in this case?)
3. +5V Salas Shunt reg. board and +/- PSU board as in Oliver's version.
My transformer is R-Core 50VA 2X15V, which if I remember correctly, actually gives near 2x18V.
Talking about the sound... After spending some time with TX2575, I love their sound so much that I've ordered a pair of TX2352. But there's still one thing, lack of expression in lower regions. It's not that it lacks just a little more punch for my taste, it's very recessed. I guess, the buffer is not there to blame and I look with suspicion towards my amp now. Dried caps? Something else?
In case of caps replacement, I would spend half of new amps budget replacing all (I have no means to detect a leaking cap, right?) of them. That being said, I accept new project suggestions for my new amp. Beware of even more noob questions coming your way!
But I promise to work on my technical knowledge, independently too.P.S. There's a thing suggesting me it could be my worn out amp caps. A little, almost inaudible from listening position hum/buzz going from one channel, when there's nothing connected except speakers to the amp. Interconnects with or without passive pre or DCB1 give two channel hum/buzz. In a couple of days I will try adding CL60, but I doubt it's a grounding issue. Or could it be? My old soviet flat doesn't have a separate safety ground wire. As I understand there's only earth connected to neutral somewhere at a breaker pannel. And the whole house could be sharing it!
That complicates virtual grounding of my Quad 707 a bit, doesn't it?
Ok, mabe I'm asking too much attention now
Thanks for all the help, anyway
Advice needed, again.
I've ordered LDR pot kit from Uriah. I'm looking for the best way to implement it in (before) my dcb1, as I don't want to do it twice. As I understand, I have these options:
1. LM317 regulator way, tapping voltage straight from DCB1.
2. Using spare DCB1 board as a shunt reg. only. (Do I need additional transformer in this case?)
3. +5V Salas Shunt reg. board and +/- PSU board as in Oliver's version.
My transformer is R-Core 50VA 2X15V, which if I remember correctly, actually gives near 2x18V.
Talking about the sound... After spending some time with TX2575, I love their sound so much that I've ordered a pair of TX2352. But there's still one thing, lack of expression in lower regions. It's not that it lacks just a little more punch for my taste, it's very recessed. I guess, the buffer is not there to blame and I look with suspicion towards my amp now. Dried caps? Something else?
In case of caps replacement, I would spend half of new amps budget replacing all (I have no means to detect a leaking cap, right?) of them. That being said, I accept new project suggestions for my new amp. Beware of even more noob questions coming your way!
P.S. There's a thing suggesting me it could be my worn out amp caps. A little, almost inaudible from listening position hum/buzz going from one channel, when there's nothing connected except speakers to the amp. Interconnects with or without passive pre or DCB1 give two channel hum/buzz. In a couple of days I will try adding CL60, but I doubt it's a grounding issue. Or could it be? My old soviet flat doesn't have a separate safety ground wire. As I understand there's only earth connected to neutral somewhere at a breaker pannel. And the whole house could be sharing it!
That complicates virtual grounding of my Quad 707 a bit, doesn't it?
Ok, mabe I'm asking too much attention now
I did option 2.
Yes you'd need a new transformer for any but option 1. Go with option 1 - by far the easiest. The power supply only needs to power some leds - not a big deal.
Is your Quad 707 over 25 years old? If so, it could be the caps - you can test them - you have to remove them and test if them for continuity and also capacitance value. They're probably fine though - that's not an old amp and Quad used good caps.
Lucas, thanks. Yes, the first way is the easiest, but I wonder will it sound much different compared to other options.
My amp must be around 14 years old. As a rule of thumb, all electrolytes in an amplifier should be replaced after 15 years, that is what I've been told by Dada Quad revision team from Belgium. Normally that kind of noise would rather be independent from a connected input.
I realise now, it could be a transformer...
My amp must be around 14 years old. As a rule of thumb, all electrolytes in an amplifier should be replaced after 15 years, that is what I've been told by Dada Quad revision team from Belgium. Normally that kind of noise would rather be independent from a connected input.
I realise now, it could be a transformer...
I don't think there is a reasonable argument that an LM317 regulator would be less than ideal for the sound, considering it isn't physically part of the LDR audio circuit at all. The audio circuit literally just goes through the LDRs. The resistor value of the LDRs is determined by how bright the adjoining LEDs are. What those LEDs are powered by isn't of massive concern (unless it's oscillating quite a lot - which is completely unlikely). There has to be SOME common sense in Hi-fi - there are those on the LDR site that will claim they can hear a difference when those LEDs are lit with batteries, but IMHO they are the same people who replace all the caps in a hi-fi with $$$$$$ Black Gates in their speakers in the hope of improvements - in other words, DAFT!
I'd be more concerned about the drain on the DCB1, but even that is irrelevant, as it is constant amperage (when not adjusting voltage) and a tiny tiny draw.
I'd be more concerned about the drain on the DCB1, but even that is irrelevant, as it is constant amperage (when not adjusting voltage) and a tiny tiny draw.
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Lucas, thanks for reply and a very encouraging one.
What made me think of dried out caps was a degraded sound of lower regions... and the hum. But maybe I'm not the right doctor here, so it's not a even a diagnosis.
For LDR PSU, I'm leaning towards options 1 & 2. What bothers me is another transformer. I'm affraid to add one more possible source of noise. My current R-Core has a separate housing and is not located on the chassis of DCB1...
I've found some ready made modules of LM317 implementation made by asian engineers : LM317 In DC or AC 4V-30V Out DC 2.5V-27V 1A Converter | eBay UK
Looks convenient. But as a diyer I would be more tempted to build my own.
What made me think of dried out caps was a degraded sound of lower regions... and the hum. But maybe I'm not the right doctor here, so it's not a even a diagnosis.
For LDR PSU, I'm leaning towards options 1 & 2. What bothers me is another transformer. I'm affraid to add one more possible source of noise. My current R-Core has a separate housing and is not located on the chassis of DCB1...
I've found some ready made modules of LM317 implementation made by asian engineers : LM317 In DC or AC 4V-30V Out DC 2.5V-27V 1A Converter | eBay UK
Looks convenient. But as a diyer I would be more tempted to build my own.
Regarding hum, isolate signal GND from power GND by 2x star GND arrangements - one for signal, isolated from everything, including the metal case, and one for electrical earth. Connect the signal GND star to the electrical GND by a CL60 thermistor. That should clean things up.
It is definitely complicated by your Russian GND-less supply
It is definitely complicated by your Russian GND-less supply
Lucas, I appreciate your suggestion. If I understand correctly, it's meant for the buffer and I intend to implement it.
Though, I'm sure the main issue is in the amp. Yesterday, I've opened it up again, and convinced myself it has a floating (virtual?) GND. No safety earth is coming in, so nothing's connected to it by default. Have to do a research if this particular scheme is helping or causing problems in my setup.
One more off topic. Geopolitical this time. This old "sans safety earth" supply shouldn't be called russian. Nationality has nothing to do with it There are some differences between soviets (almost a historical state of mind), russians and lithuanians (formerly sovietized nations)
BTW, similar supply, but with additional safety implementations is still used in Switzerland and sometimes found is Scandinavian old buildings.
Here, we are moving away from it.
Though, I'm sure the main issue is in the amp. Yesterday, I've opened it up again, and convinced myself it has a floating (virtual?) GND. No safety earth is coming in, so nothing's connected to it by default. Have to do a research if this particular scheme is helping or causing problems in my setup.
One more off topic. Geopolitical this time. This old "sans safety earth" supply shouldn't be called russian. Nationality has nothing to do with it
There are some differences between soviets (almost a historical state of mind), russians and lithuanians (formerly sovietized nations) BTW, similar supply, but with additional safety implementations is still used in Switzerland and sometimes found is Scandinavian old buildings.
Here, we are moving away from it.
Hi-tech electronics manufacturers, like Quad, use a different system than is possible for DIYers these days.
We generally use Class 0 Earthing arrangement, where all earths are connected to chassis, and lead out to electrical earth.
Modern manufacturers use Class 6 Earthing arrangement, where they can eliminate the need for an electrical earth by absolutely guaranteeing that it is impossible for the metal case, etc. to become live, even if a wire comes loose, by double insulating everything inside the chassis. We can't easily do that. Nobody does it that way here. Quad can, and it should cause you no problems, unless transformer AC hum noise escapes up the interconnect shields, into the pre-amp and into your signal, which has happened to me.
Sorry for calling your system Russian. I meant Soviet of course. Whatever it is, it isn't ideal. I'm sure glad we've always had a safety earth in the UK though - it saves a lot of lives! If I make a mistake in my Hi-fi and so much as 30mA goes into my body or to earth, a residual circuit device trips the switch, and I am saved a nice big shock (especially working with valves.)
We generally use Class 0 Earthing arrangement, where all earths are connected to chassis, and lead out to electrical earth.
Modern manufacturers use Class 6 Earthing arrangement, where they can eliminate the need for an electrical earth by absolutely guaranteeing that it is impossible for the metal case, etc. to become live, even if a wire comes loose, by double insulating everything inside the chassis. We can't easily do that. Nobody does it that way here. Quad can, and it should cause you no problems, unless transformer AC hum noise escapes up the interconnect shields, into the pre-amp and into your signal, which has happened to me.
Sorry for calling your system Russian. I meant Soviet of course. Whatever it is, it isn't ideal. I'm sure glad we've always had a safety earth in the UK though - it saves a lot of lives! If I make a mistake in my Hi-fi and so much as 30mA goes into my body or to earth, a residual circuit device trips the switch, and I am saved a nice big shock (especially working with valves.)
It's not that current power instalation is completely unsafe. The fuse blows when there's a loose wire on chassis, the switch trips if there's fault. Earth is connected with neutral, but at one distant point.
Is it possible that this kind of noise affects only one side? Is there a cure to this? Thermistor?
Is it possible that this kind of noise affects only one side? Is there a cure to this? Thermistor?
Thanks for all information, anyway. It helps to get a full picture of all possible troublemakers.
Yes, you are right, I should make a proper buffer grounding and then look further.
Recap: with my passive pre (2 mono atenuators only), I have got same noise results as with the DCB1 (both channels humming). I've got different results with when no interconnects connected (1 channel noise) to the amp.
Yes, you are right, I should make a proper buffer grounding and then look further.
Recap: with my passive pre (2 mono atenuators only), I have got same noise results as with the DCB1 (both channels humming). I've got different results with when no interconnects connected (1 channel noise) to the amp.