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Post by julesd68 on Apr 7, 2021 7:45:21 GMT
Just wondering if you finished this build bigman80 or another version of it? Would be interesting to know how it worked out. |
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Post by bigman80 on Apr 7, 2021 11:10:41 GMT
Just wondering if you finished this build bigman80 or another version of it? Would be interesting to know how it worked out. Hi Jules, I've been absolutely under the kosh with Phonostage builds so my prototype Preamp box is still in use. I am hoping to get some time in the next two weeks to TRY and put mine together. There will be a Phonostage going inside that one though so again it won't be "as it should be" There are now two proper builds in existence. Both in Australia. One dislodged a Croft 25R and the other dislodged a high cost Naim pre...but I can't recall the model number. I'm not familiar with Naim either so I am not sure if it's good...just that it was expensive. I'm very happy with the performance. I am reluctant to "Hype up" the unit as it is mine and that's not the way I work. I should have a rough around the edges loaner available in a couple of weeks, so if you fancy giving it a listen, you are more than welcome to have it for a week or so. 1x RCA input and output. Unity gain. OCC wiring Custom stepped attenuator etc As it all would be in the full build. |
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Post by julesd68 on Apr 7, 2021 12:03:31 GMT
Hi Oliver,
Great, it would be really interesting to have a listen. I have two new preamps to compare it to - a passive that's an improvement on the Chinese RVC and also an active pre that is waiting for a run out. I'll most likely wait to try the active after a go with yours as it requires a gain adjustment under the hood of my power amp.
Cheers.
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Post by bigman80 on Apr 7, 2021 12:12:27 GMT
Hi Oliver, Great, it would be really interesting to have a listen. I have two new preamps to compare it to - a passive that's an improvement on the Chinese RVC and also an active pre that is waiting for a run out. I'll most likely wait to try the active after a go with yours as it requires a gain adjustment under the hood of my power amp. Cheers. Yeah no worries. I'll give you a shout in a week or two. Hopefully I'll have the new one up and running by then, if not.... It'll be longer 🤣🤣 |
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Post by julesd68 on Apr 7, 2021 13:00:36 GMT
LOL - no worries, whenever it's ready!
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Post by julesd68 on May 1, 2021 15:02:19 GMT
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Post by bigman80 on May 1, 2021 17:21:39 GMT
It's a preamp that buffers the output signal. I had one a few years back. I ran mine at 1.2A and it needed huge heatsinks. I put a Khozmo in it and an Elna selector Switch. Tantalum resistors and Obligatto Caps. It was very good, but as it only buffers the output IIRC, it means you still have to be aware of impedance matching on the input. I sold it when I got a Neurochrome 8x2, although I'm not entirely sure it was subjectivity "better". Not sure about how I feel over this eBay 'Joe' making Nelson Pass designed gear for profit, when Pass gave it to DIY community for free. Seems a bit unethical IMHO. Nice looking build, shit transformer and I don't like PRP resistors or the EIZZ Attenuators. They use carbon resistors and thats a big no-no IMO. The EIZZ selector switch is ok, but the mechanism on the inside failed on the one I bought. Bunching the cables together also increases cross Talk. Looks pretty, but not how I'd do it. |
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Post by julesd68 on May 1, 2021 21:22:20 GMT
Thanks for the info Oliver!
As a non DIY punter I don't think I would have a problem with it if I thought the product ticked all the boxes in terms of quality components and represented VFM. But in this case I would 'pass' on both counts.
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Post by julesd68 on Oct 13, 2021 21:30:32 GMT
What might be any advantages / disadvantages of using a fader (parallel plate potentiometer) instead of a volume pot??  |
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Post by MartinT on Oct 13, 2021 22:05:21 GMT
What might be any advantages / disadvantages of using a fader (parallel plate potentiometer) instead of a volume pot?? Most of them have poor quality control so a L/R pair may not track perfectly. There's just been a lot more effort made with rotary pots, as well as switched pots for which I don't believe there's a linear equivalent. |
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Post by Mr Whippy on Oct 13, 2021 22:17:53 GMT
What might be any advantages / disadvantages of using a fader (parallel plate potentiometer) instead of a volume pot?? It's still a pot. Rather than working in a circular fashion, it operates in a straight line. PS Audio's thinking of doing away with the volume control and varying the gain stage of the power amplifier to control level, seems to offer the ideal method of control. |
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Post by julesd68 on Oct 13, 2021 22:51:44 GMT
What might be any advantages / disadvantages of using a fader (parallel plate potentiometer) instead of a volume pot?? It's still a pot. Rather than working in a circular fashion, it operates in a straight line. PS Audio's thinking of doing away with the volume control and varying the gain stage of the power amplifier to control level, seems to offer the ideal method of control. Yes indeedy - I omitted the word 'rotary' before 'volume pot' ...  I will have a look at what PS Audio are doing there, sounds interesting. |
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Post by julesd68 on Nov 27, 2021 18:40:00 GMT
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Post by Slinger on Nov 27, 2021 18:59:03 GMT
I have no idea, and that's after reading all the info on that page. They do, though, produce a fine line in technical bollocks it has to be said, and it's great the way they've copied it from the manufacturer's site, complete with original typos.  |
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Post by julesd68 on Nov 27, 2021 20:19:37 GMT
LoL - a 15k amp and the manufacturer can't get their native language translated properly - how difficult can it be??
Also I'm amazed how many retailers don't bother to read what they are copy and pasting, or just don't care - not a good look ...
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Post by ant on Nov 29, 2021 20:27:28 GMT
It appears to be an autoformer or a tvc given the blather about laminations and windings
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Post by MartinT on Nov 29, 2021 21:22:37 GMT
Agreed, something like Max Townshend's Allegri?
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Post by puffin on Dec 9, 2021 13:25:49 GMT
Anyone here use a Pre with Light Dependant Resistors? I built one about 10 years ago from the details on Diyaudio posted by the designer of the Lightspeed Attenuator. It has never left my system and is still gooing strong all these years later. My impressions of the SQ is that for a passive attenuator it sounds nothing like any other passive I have used. Detail retrieval, depth and timbre are IMO excellent. I also find that there is an airiness which other passives lack.
I did pay a lot of attention to the PS by using some Teddy Pardo DIY Power Regs and a JLH Ripple eater.
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ben
Rank: Starter
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Post by ben on Feb 2, 2022 6:19:16 GMT
Puffin your post is relevant for my question/reflection, which is primarily addressed to Bigman80. In another post on another forum Bigman80 reflected he was not that keen on LDR attenuators and preferred his Slagle autoformer over the Stereo Coffee LDR he tried and that better still was his stepped Khozmo resistor attenuator combined with a unity gain buffer.
In post 292 Bigman80 wrote: "...i like the transparency and soundstage of a good passive but the lack of drive always bothered me, hence the new buffer preamp I'm building. Makes the vagaries a none issue."
My question for anyone who has experimented with IC cable length after a passive volume control is what length cable did you use?
Could an IC cable any longer than a very very short one lead to the "lack of drive" Bigman80, and many others, have heard?
In particular, because you, Bigman80, tried several passive attenutors, I would like to know what length cable you used between the passive attenuators you tried, including the Stereo Coffee LDR, and the power amplifiers before you started using a unity gain buffer after the attenuator?
For what it is worth back in 2018 I tried a Stereo Coffee LDR and compared it with my Dave Slagle "Autoformer Modules" with a 30cm Van Den Hul The Name IC cable and preferred the Stereo Coffee. The difference wasn't subtle. The Slagle sounded veiled and distant by comparison. But it was on someone else's system so I don't have extensive experience in comparing the two. I wonder if the Stereo Coffee would have sounded even better with a much shorter IC cable. It may sound even better with a unity gain buffer. I just don't know how much the buffer is likely to add if the IC cables are kept really short, i.e., under 7 to 10 cm.
For any that didn't know, from what I have read, Autoformer and transformer based attenuators are meant to be relatively immune to the length of IC between them and the power amplifier, while resistor based attenuators are not.
For what its worth I used to have Endler attenuators, which were the shunt step type that plugged directly into the RCA socket of the power amplifier. They had more sparkle and mid and high frequency refinement than the Slagle Autoformer Modules, but lost dynamics at low volume and seemed to perish after a few years to become very scratchy. They are not available anymore. Nor are their more expensive competitors EVS nude attenuators, which I never tried. In his blog on his website, when it was still on the internet, Scott Endler said there was much to be gained sonically by keeping the IC cable under 10cm. Hence my question regarding cable length addressed to Bigman80 who has trialed several passive attenuators.
Kind Regards,
Ben
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Post by bigman80 on Feb 2, 2022 7:19:26 GMT
Puffin your post is relevant for my question/reflection, which is primarily addressed to Bigman80. In another post on another forum Bigman80 reflected he was not that keen on LDR attenuators and preferred his Slagle autoformer over the Stereo Coffee LDR he tried and that better still was his stepped Khozmo resistor attenuator combined with a unity gain buffer. In post 292 Bigman80 wrote: "...i like the transparency and soundstage of a good passive but the lack of drive always bothered me, hence the new buffer preamp I'm building. Makes the vagaries a none issue." My question for anyone who has experimented with IC cable length after a passive volume control is what length cable did you use? Could an IC cable any longer than a very very short one lead to the "lack of drive" Bigman80, and many others, have heard? In particular, because you, Bigman80, tried several passive attenutors, I would like to know what length cable you used between the passive attenuators you tried, including the Stereo Coffee LDR, and the power amplifiers before you started using a unity gain buffer after the attenuator? For what it is worth back in 2018 I tried a Stereo Coffee LDR and compared it with my Dave Slagle "Autoformer Modules" with a 30cm Van Den Hul The Name IC cable and preferred the Stereo Coffee. The difference wasn't subtle. The Slagle sounded veiled and distant by comparison. But it was on someone else's system so I don't have extensive experience in comparing the two. I wonder if the Stereo Coffee would have sounded even better with a much shorter IC cable. It may sound even better with a unity gain buffer. I just don't know how much the buffer is likely to add if the IC cables are kept really short, i.e., under 7 to 10 cm. For any that didn't know, from what I have read, Autoformer and transformer based attenuators are meant to be relatively immune to the length of IC between them and the power amplifier, while resistor based attenuators are not. For what its worth I used to have Endler attenuators, which were the shunt step type that plugged directly into the RCA socket of the power amplifier. They had more sparkle and mid and high frequency refinement than the Slagle Autoformer Modules, but lost dynamics at low volume and seemed to perish after a few years to become very scratchy. They are not available anymore. Nor are their more expensive competitors EVS nude attenuators, which I never tried. In his blog on his website, when it was still on the internet, Scott Endler said there was much to be gained sonically by keeping the IC cable under 10cm. Hence my question regarding cable length addressed to Bigman80 who has trialed several passive attenuators. Kind Regards, Ben Hi Ben, LDR preamps (that I have heard/trialed) had very poor channel matching, resulting in a rather smeared image. One I had here also had this really cool trick of changing the volume randomly on either channel by itself....even though you didn't want it to. The Stereo coffee also had leading edge emphasis, sounded "shouty" and rough. I'm not sure why and as always, there may be another reason for it, but the Slagle was preferable at the time. The cable lengths In this discussion are unlikely to be of consequence, as the system has never used any length over 1m. I built a passive preamp recently. Using a TKD potentiometer, PC-Triple C wiring and WBT sockets. I did a comparison Vs my BT2 unity gain preamp by just swapping the pot between units. Grip and control of the low frequencies is where the passive fails for me. "Drive" may have been the wrong description, but the BT2 has a better grip and control of the LF. This leads to a higher general resolution as the bass isn't treading in everything. I also noticed that adding gain seemed to change things again. Stiffening up the LF....which I liked and may employ long term. Hope that helps. |
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