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Post by Deleted on Mar 12, 2019 15:38:50 GMT
Hi All,
Today Alan brought round his latest bit of work, a commissioned LDR Preamp build. I believe it's a Stereo Coffee kit and is the latest version.
As I'm becoming more and more convinced that Digital could be the future, for me, I decided to use the Raspberry Pi.
Unfortunately, I completely forgot to take a photo so I'll see if I can get one emailed over to me.
This unit has been built into a nice Aluminium enclosure which actually looks very nice in the flesh. Rather than write a full scale review based on an hour or so's listening, I'll just give a brief overview of the experience.
First impressions were good, it sounded a little lean on the material we listened to and the sound stage was no wider than the speakers. We let it play for a while to warm up and as we listened, it got a bit better.
The sounstage never threatened to extend beyond the speakers, however. The tone also remained a little on the lean side and at one point I remarked that it sounded "a little bit shouty"
Bass was full and textured but less grip than with the DCB1. I felt it needed a bit more in the mids to flesh out the vocals.
Vocals were clean and clear but again, I really needed a bit more body.
Instruments were well separated and easy to define too. This preamp doesn't do too much wrong imo, and for the money, seems like a sensible buy.
I believe the kit is under £300 and if you need a preamp for under £300, I'd certainly consider it.
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Post by macca on Mar 12, 2019 15:53:53 GMT
Not that exciting then?
The only one that really impressed me was the Tortuga Audio effort. But that was about £800 as a kit IIRC.
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Post by Deleted on Mar 12, 2019 16:54:33 GMT
Not that exciting then? The only one that really impressed me was the Tortuga Audio effort. But that was about £800 as a kit IIRC. It was good but nothing has compared to the DCB1 imo so it's very difficult to really be excited by anything less. As far as preamps under £300 go, it's a wise purchase. There's a couple of preamps out there I think would be exciting but getting access to them is gonna be mega expensive |
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Post by macca on Mar 12, 2019 16:58:45 GMT
See if you can get a Mark Levinson  Got to say I am also no longer bothered about pre-amps since getting the DCB1. There's a couple I've heard over the years that are on a par with it, possibly slightly better (would need to do a back to back listen to be sure) but they are thousands of quid and a DCB1 can be built for under £200 |
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Post by antonio on Mar 12, 2019 17:05:41 GMT
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Post by karma67 on Mar 12, 2019 17:24:10 GMT
Hi All, Today Alan brought round his latest bit of work, a commissioned LDR Preamp build. I believe it's a Stereo Coffee kit and is the latest version. As I'm becoming more and more convinced that Digital could be the future, for me, I decided to use the Raspberry Pi. Unfortunately, I completely forgot to take a photo so I'll see if I can get one emailed over to me. This unit has been built into a nice Aluminium enclosure which actually looks very nice in the flesh. Rather than write a full scale review based on an hour or so's listening, I'll just give a brief overview of the experience. First impressions were good, it sounded a little lean on the material we listened to and the sound stage was no wider than the speakers. We let it play for a while to warm up and as we listened, it got a bit better. The sounstage never threatened to extend beyond the speakers, however. The tone also remained a little on the lean side and at one point I remarked that it sounded "a little bit shouty" Bass was full and textured but less grip than with the DCB1. I felt it needed a bit more in the mids to flesh out the vocals. Vocals were clean and clear but again, I really needed a bit more body. Instruments were well separated and easy to define too. This preamp doesn't do too much wrong imo, and for the money, seems like a sensible buy. I believe the kit is under £300 and if you need a preamp for under £300, I'd certainly consider it. i think steve prefered the dcb1 too,the one he built didnt last long in his system. |
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Post by Deleted on Mar 12, 2019 17:34:43 GMT
See if you can get a Mark Levinson Got to say I am also no longer bothered about pre-amps since getting the DCB1. There's a couple I've heard over the years that are on a par with it, possibly slightly better (would need to do a back to back listen to be sure) but they are thousands of quid and a DCB1 can be built for under £200 You can eek out more performance from the one you have by upping the Amps mate. 1.2A is where mine is at and it's been untouchable since. A couple of judiciously considered upgrades like the AN Tantalum resistors for the important bits have yielded a great return. The two WIMA caps can be improved on too. That's what I'll do with mine next. Just the caps as I have the AN Tantalum resistors. Believe me, they are superb. |
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Post by Deleted on Mar 12, 2019 17:35:11 GMT
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Post by Deleted on Mar 12, 2019 17:37:37 GMT
Hi All, Today Alan brought round his latest bit of work, a commissioned LDR Preamp build. I believe it's a Stereo Coffee kit and is the latest version. As I'm becoming more and more convinced that Digital could be the future, for me, I decided to use the Raspberry Pi. Unfortunately, I completely forgot to take a photo so I'll see if I can get one emailed over to me. This unit has been built into a nice Aluminium enclosure which actually looks very nice in the flesh. Rather than write a full scale review based on an hour or so's listening, I'll just give a brief overview of the experience. First impressions were good, it sounded a little lean on the material we listened to and the sound stage was no wider than the speakers. We let it play for a while to warm up and as we listened, it got a bit better. The sounstage never threatened to extend beyond the speakers, however. The tone also remained a little on the lean side and at one point I remarked that it sounded "a little bit shouty" Bass was full and textured but less grip than with the DCB1. I felt it needed a bit more in the mids to flesh out the vocals. Vocals were clean and clear but again, I really needed a bit more body. Instruments were well separated and easy to define too. This preamp doesn't do too much wrong imo, and for the money, seems like a sensible buy. I believe the kit is under £300 and if you need a preamp for under £300, I'd certainly consider it. i think steve prefered the dcb1 too,the one he built didnt last long in his system. Yes, you're quite right mate. Certainly good for the money but like Macca said, if you can build a DCB1 for the same price, that's what I'd do. |
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Post by dsjr on Mar 12, 2019 17:42:16 GMT
See if you can get a Mark Levinson Got to say I am also no longer bothered about pre-amps since getting the DCB1. There's a couple I've heard over the years that are on a par with it, possibly slightly better (would need to do a back to back listen to be sure) but they are thousands of quid and a DCB1 can be built for under £200 You need a proper balanced preamp macca! Krell have said I seem to recall that the performance of your particular series of amps is curtailed somewhat if not fed a balanced signal - explained better in ASR regarding reductions in many distortions as tying one 'leg' to ground as I did and you still seem to be doing, is a bit of a bodge as your amp is practically 'balanced' right from the input sockets and rather insensitive to boot, although that doesn't appear to bother you as it sis me... Ollie's Krell is single ended on the input and a totally different and simpler circuit by the look of it.
I dive in because I remember how bloody good the ML28 was when I heard it and possibly Camack? socketry aside, it'd be a perfect and honest match I reckon. I suspect it's better than period ARC and Krell offerings too. having said the above -
I still love these units as long as they work and someone can fix them...
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Post by macca on Mar 12, 2019 17:48:11 GMT
See if you can get a Mark Levinson Got to say I am also no longer bothered about pre-amps since getting the DCB1. There's a couple I've heard over the years that are on a par with it, possibly slightly better (would need to do a back to back listen to be sure) but they are thousands of quid and a DCB1 can be built for under £200 You can eek out more performance from the one you have by upping the Amps mate. 1.2A is where mine is at and it's been untouchable since. A couple of judiciously considered upgrades like the AN Tantalum resistors for the important bits have yielded a great return. The two WIMA caps can be improved on too. That's what I'll do with mine next. Just the caps as I have the AN Tantalum resistors. Believe me, they are superb. hard to imagine to being better than it is at the moment but that's always easy to say until you hear better. Steve says he will upgrade it for me when he's up in this neck of the woods later in the year. Seriously though had a bit if a session last night and didn't want to turn it off. It's got both the wallop and the delicacy, did not think I would ever be able to get my system to that level on a beer budget. We are on for Friday btw if you are still free. Will try and get there for about 1100 so we're not rushed for time. |
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Post by macca on Mar 12, 2019 17:56:52 GMT
See if you can get a Mark Levinson Got to say I am also no longer bothered about pre-amps since getting the DCB1. There's a couple I've heard over the years that are on a par with it, possibly slightly better (would need to do a back to back listen to be sure) but they are thousands of quid and a DCB1 can be built for under £200 You need a proper balanced preamp macca! Krell have said I seem to recall that the performance of your particular series of amps is curtailed somewhat if not fed a balanced signal - explained better in ASR regarding reductions in many distortions as tying one 'leg' to ground as I did and you still seem to be doing, is a bit of a bodge as your amp is practically 'balanced' right from the input sockets and rather insensitive to boot, although that doesn't appear to bother you as it sis me... Ollie's Krell is single ended on the input and a totally different and simpler circuit by the look of it.
I dive in because I remember how bloody good the ML28 was when I heard it and possibly Camack? socketry aside, it'd be a perfect and honest match I reckon. I suspect it's better than period ARC and Krell offerings too. having said the above -
I still love these units as long as they work and someone can fix them...
Lol shame you are so far away Dave, you wouldn't be saying that if you came round and had a listen! Yes the 50s and the MkII are not the same amp but the 'signature' is practically identical. Ollie's system sounds a lot like mine, if we had the same speakers they would probably be almost indistinguishable. Not saying an balanced pre-amp might not add a bit more, I take your point about the 50S being optimised for that. I suppose there is no reason why a balanced DCB1 could not be made? But really it is so good at the moment I could happily stop where I am. I highly rate the ML gear, no question about it but I'm not paying £3K for a second-hand pre-amp. Plus I am all for the idea that you don't need or want an active pre-amp with digital. The reason for rubbish digital sound is rubbish active pre-amps. As soon as I went passive I realised that 'pure, perfect sound forever' was not just a lame marketing slogan. |
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Post by Deleted on Mar 12, 2019 18:18:39 GMT
You need a proper balanced preamp macca! Krell have said I seem to recall that the performance of your particular series of amps is curtailed somewhat if not fed a balanced signal - explained better in ASR regarding reductions in many distortions as tying one 'leg' to ground as I did and you still seem to be doing, is a bit of a bodge as your amp is practically 'balanced' right from the input sockets and rather insensitive to boot, although that doesn't appear to bother you as it sis me... Ollie's Krell is single ended on the input and a totally different and simpler circuit by the look of it.
I dive in because I remember how bloody good the ML28 was when I heard it and possibly Camack? socketry aside, it'd be a perfect and honest match I reckon. I suspect it's better than period ARC and Krell offerings too. having said the above -
I still love these units as long as they work and someone can fix them...
Lol shame you are so far away Dave, you wouldn't be saying that if you came round and had a listen! Yes the 50s and the MkII are not the same amp but the 'signature' is practically identical. Ollie's system sounds a lot like mine, if we had the same speakers they would probably be almost indistinguishable. Not saying an balanced pre-amp might not add a bit more, I take your point about the 50S being optimised for that. I suppose there is no reason why a balanced DCB1 could not be made? But really it is so good at the moment I could happily stop where I am. I highly rate the ML gear, no question about it but I'm not paying £3K for a second-hand pre-amp. Plus I am all for the idea that you don't need or want an active pre-amp with digital. The reason for rubbish digital sound is rubbish active pre-amps. As soon as I went passive I realised that 'pure, perfect sound forever' was not just a lame marketing slogan. Yes, 100% still on. I'll PM the address over to you. I didn't think raising the DCB1 from 600mA would actually do ALL that much. It did but don't expect a doubling of performance because thats not how it is. I am eternally grateful to Steve and Alan as together we all chipped in with our ideas, bought resistors in bulk and saved a fair few quid. I just wish id have bought the good capacitors at the same time but hey, i'd have no upgrades to do now! The raising of the "A" just increases all of the good points you already have and the only downside is the heat. Steve has some massive heat sinks so yes, when he's up this way, get him on it. It may be a while as he's looking after a family member who's had ill health. Can the DCB1 be made into a balanced Pre? I'll find out. I just don't know how the ML "could" be better. Honestly, we talk endlessly about synergy in the system and to my ears, the Source>Spotfire>DCB1>Spotfire>Krell line has it in spades. I'd be up for it though if anyone wants a bake off. |
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Post by dsjr on Mar 12, 2019 18:19:28 GMT
You need a proper balanced preamp macca! Krell have said I seem to recall that the performance of your particular series of amps is curtailed somewhat if not fed a balanced signal - explained better in ASR regarding reductions in many distortions as tying one 'leg' to ground as I did and you still seem to be doing, is a bit of a bodge as your amp is practically 'balanced' right from the input sockets and rather insensitive to boot, although that doesn't appear to bother you as it sis me... Ollie's Krell is single ended on the input and a totally different and simpler circuit by the look of it.
I dive in because I remember how bloody good the ML28 was when I heard it and possibly Camack? socketry aside, it'd be a perfect and honest match I reckon. I suspect it's better than period ARC and Krell offerings too. having said the above -
I still love these units as long as they work and someone can fix them...
Lol shame you are so far away Dave, you wouldn't be saying that if you came round and had a listen! Yes the 50s and the MkII are not the same amp but the 'signature' is practically identical. Ollie's system sounds a lot like mine, if we had the same speakers they would probably be almost indistinguishable. Not saying an balanced pre-amp might not add a bit more, I take your point about the 50S being optimised for that. I suppose there is no reason why a balanced DCB1 could not be made? But really it is so good at the moment I could happily stop where I am. I highly rate the ML gear, no question about it but I'm not paying £3K for a second-hand pre-amp. Plus I am all for the idea that you don't need or want an active pre-amp with digital. The reason for rubbish digital sound is rubbish active pre-amps. As soon as I went passive I realised that 'pure, perfect sound forever' was not just a lame marketing slogan. I understand the arguments about single ended vs. balanced, it's just in your case that's all and bearing in mind the amp topology. I'm not sure Ollie's amp would sound like yours directly though, the original 50 definitely didn't, but you may be right and it's all in the preamp choice... I really must be deaf, as the passive I used into the 50S with proper stepped attenuator (not the shitty Tisbury things) was most often one or two notches from max with a CD source when herself went out...
ASR gave a definite thumbs down for the LDR thing they tested recently, but they have a 'Coffee Table' made one which will be properly tested at some point. How can resistors *add* distortion as these ldr types seem to do? The distortion and noise in a simple Alps film pot is little different to the analyser I recall and response wide open pretty much..
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Post by macca on Mar 12, 2019 18:41:23 GMT
Lol shame you are so far away Dave, you wouldn't be saying that if you came round and had a listen! Yes the 50s and the MkII are not the same amp but the 'signature' is practically identical. Ollie's system sounds a lot like mine, if we had the same speakers they would probably be almost indistinguishable. Not saying an balanced pre-amp might not add a bit more, I take your point about the 50S being optimised for that. I suppose there is no reason why a balanced DCB1 could not be made? But really it is so good at the moment I could happily stop where I am. I highly rate the ML gear, no question about it but I'm not paying £3K for a second-hand pre-amp. Plus I am all for the idea that you don't need or want an active pre-amp with digital. The reason for rubbish digital sound is rubbish active pre-amps. As soon as I went passive I realised that 'pure, perfect sound forever' was not just a lame marketing slogan. I understand the arguments about single ended vs. balanced, it's just in your case that's all and bearing in mind the amp topology. I'm not sure Ollie's amp would sound like yours directly though, the original 50 definitely didn't, but you may be right and it's all in the preamp choice... I really must be deaf, as the passive I used into the 50S with proper stepped attenuator (not the shitty Tisbury things) was most often one or two notches from max with a CD source when herself went out...
ASR gave a definite thumbs down for the LDR thing they tested recently, but they have a 'Coffee Table' made one which will be properly tested at some point. How can resistors *add* distortion as these ldr types seem to do? The distortion and noise in a simple Alps film pot is little different to the analyser I recall and response wide open pretty much..
I didn't see the LDR review on ASR I'll take a look. Not got any volume issues with the DCB1 into the Krell nor did I with the NVA P90SA. Speakers are high efficiency though. My LDR pre-amp has the opposite problem - too much volume. Although I've never tried it with the Krell. |
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Bigman80
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Post by Bigman80 on Mar 12, 2019 18:46:57 GMT
See if you can get a Mark Levinson Got to say I am also no longer bothered about pre-amps since getting the DCB1. There's a couple I've heard over the years that are on a par with it, possibly slightly better (would need to do a back to back listen to be sure) but they are thousands of quid and a DCB1 can be built for under £200 You need a proper balanced preamp macca! Krell have said I seem to recall that the performance of your particular series of amps is curtailed somewhat if not fed a balanced signal - explained better in ASR regarding reductions in many distortions as tying one 'leg' to ground as I did and you still seem to be doing, is a bit of a bodge as your amp is practically 'balanced' right from the input sockets and rather insensitive to boot, although that doesn't appear to bother you as it sis me... Ollie's Krell is single ended on the input and a totally different and simpler circuit by the look of it. I dive in because I remember how bloody good the ML28 was when I heard it and possibly Camack? socketry aside, it'd be a perfect and honest match I reckon. I suspect it's better than period ARC and Krell offerings too. having said the above -
I still love these units as long as they work and someone can fix them...
My mate has had so may Krell and Levinsn I’ve lost count. The only Krell he’s had any time for was KSA50 mk1. Even then he’s of the opinion that early levinson are a league apart. His biggest regret is selling his early Levinson monos. I hope one day to try early Levinson myself. |
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Post by dsjr on Mar 12, 2019 19:19:04 GMT
I forget the brand, but 'coffee table' all but took over a thread and has arranged for Amir to test it thoroughly, so we shall see.
Post 37 and ldr discussion kind-of takes over for a while.
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Post by macca on Mar 12, 2019 20:20:20 GMT
I have had a fairly extensive listen to that one too and it was good. The measurements are poor though aren't they? |
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Post by alit on Mar 13, 2019 8:48:29 GMT
LDR’s are not linear, Nick over on AT measured an LDR pre.
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Post by Deleted on Mar 13, 2019 9:50:49 GMT
LDR’s are not linear, Nick over on AT measured an LDR pre. Yup, some feverish searching found a list of results demonstrating that LDR isn't really the way to go. |
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Post by firebottle on Mar 13, 2019 10:24:48 GMT
LDR’s are not linear, Nick over on AT measured an LDR pre. I was about to say the same, the resistive element isn't linear. The LDR preamp is the bottom one in this pic:    |
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Post by Deleted on Mar 13, 2019 13:45:54 GMT
Thanks for the pics Alan.
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Post by Deleted on Mar 26, 2019 7:02:37 GMT
LDR’s are not linear, Nick over on AT measured an LDR pre. LDR's simply reflect back the quality or lack of quality -of the circuitry powering them. |
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Post by Deleted on Mar 26, 2019 13:55:09 GMT
LDR’s are not linear, Nick over on AT measured an LDR pre. LDR's simply reflect back the quality or lack of quality -of the circuitry powering them. So you are doubting Nick Gorham's ability to conduct measurements? The man is a legend here in the UK and has the reputation of someone who is a Top Class designer and is certainly capable of conducting tests of this manner and relay his experience without Bias. He is probably THE only hifi forum personalities who is welcome on ANY forum. That's twice now that you've blamed the power supply for the performance of the LDR. Your literature clearly explains that it can be powered by 12v AC or 12-18v DC. The unit used here was well within the specification you sent out. As far as I am concerned, it's within spec, built by a more than qualified engineer with over 30 years experience. The result is the result. As I also stated, I didn't dislike the LDR. It just didn't outperform THE DCB1 WHICH, I might add, was twice the price. |
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Post by Deleted on Mar 26, 2019 17:29:53 GMT
The unit measured as I understand by Nick was not a stereo coffee board set, rather another brand of LDR.
My comments were simply to say that LDR's reflect the way they are powered, which is exactly what happens.
Which is not a criticism on the way, whatever was measured, was measured.
If you have ever connected LDR's to your audio system as an attenuator - you will notice they are good straight away, and its this assumption
that they cannot possibly get any better, that has most people confused. Some providers of LDR kits then provide the very bare basics of parts to power them,
not realising, just how good LDR's can be where better parts and design is used. LDR's as you may know are current devices and their available attenuation range
requires less than 2ma of current. The bare basic designs cater for much heavier currents sadly ignoring the delicate nature of what is actually needed.
A good design for instance will separate the cathode from ground, there is then ability to have silence at zero volume, and contact-less input switching
as well as use of a single gang potentiometer in the cathodes to achieve attenuation.
12v AC is the easiest form of connection for the stereo coffee kits, and is what most people use.It can though also be powered with DC, where DC is the
available choice of power. 12v DC is noted though at the lowest end of the needed range.
I have in this case offered on the AOS forum to update the main board to be optimum with 12v in this case DC powered by battery.
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Post by Deleted on Mar 26, 2019 17:51:24 GMT
Well, I'll hold my hands up to the fact I have no expertise in the areas of LDR attenuation.
I am one who believes that anything can be improved and if you are suggesting the Stereo Coffee could be improved by improving the PSU, I accept that but what must be acknowledged is that the one I heard was in spec.
Again, I did like the LDR, regardless of how it measures or that of how any LDR attenuation measures.
I use valves and fully concede that while the world is aiming for total THD Elimination, I actually quite enjoy a little bit of THD!
Yes it's good and Yes, I also think that if the kit is available for £300 or less, this is definitely a preamp I would look into.
Trouble is, it came up against a preamp I consider to be the best I've heard, especially in my own system. Its been pushed to its limit in terms of what one board can do and been filled with very well selected parts. Its going to take something very special to dislodge it.
If you would like to submit and optimal version of your Stereo Coffee for a bake off, I will happily compared them again.
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Post by macca on Mar 26, 2019 18:00:02 GMT
If you can send me the uprated board for mine Mr Coffee I will get it installed and bake it off against the DCB1, don't mind paying for it and we can use my FedEx account for the shipping if you like. The problem with mine now is either too quiet or way too loud, no in between. That's if I can somehow avoid eating the cadmium and dying of course.
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Post by Deleted on Mar 26, 2019 18:01:45 GMT
"Well, I'll hold my hands up to the fact I have no expertise in the areas of LDR attenuation. I am one who believes that anything can be improved and if you are suggesting the Stereo Coffee could be improved by improving the PSU, I accept that but what must be acknowledged is that the one I heard was in spec. Again, I did like the LDR, regardless of how it measures or that of how any LDR attenuation measures. I use valves and fully concede that while the world is aiming for total THD Elimination, I actually quite enjoy a little bit of THD! Yes it's good and Yes, I also think that if the kit is available for £300 or less, this is definitely a preamp I would look into. Trouble is, it came up against a preamp I consider to be the best I've heard, especially in my own system. Its been pushed to its limit in terms of what one board can do and been filled with very well selected parts. Its going to take something very special to dislodge it. If you would like to submit and optimal version of your Stereo Coffee for a bake off, I will happily compared them again. " As soon as I can get time to send you a 12v AC powered unit for bake- off I will. Let us clarify what was measured by Nick was not a stereo coffee board set, and assuming all LDR attenuators will measure the same, is erroneous. ( Yes I am getting a unit to Amir ! too, to be measured ) |
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Post by Deleted on Mar 26, 2019 18:17:05 GMT
Ok, accepted but what was it?
Sure, I'll give the 12v Stereo Coffee the run over and see what I can get out of it.
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Post by Deleted on Jun 13, 2019 6:03:49 GMT
To resurrect an old thread, I have recently started to look further into the merits (or not) of LDR's and came across this article (again)
www.neurochrome.com/tortuga-audio-ldr3/
Chris has again stated that his LDR Pre's are distortion free and that the poor performance of the LDR's (Tortuga's unit) is down to poor circuit implementation.
I have suggested he should send one of his units to the forum that tests kit for free, but I can't recall the name of it. Can anyone remember? I think Dave highlighted them before. |
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