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85.19.92.6
Hi !
i see that usually DIYers prefer to build from the scratch ... with the smartest ones even designing their creations.
I am sincerely amazed by these people. I would like to do the same myself but i have just no hopes.
However, i am also intrigued by the modification of something existing and already decent.
I am an avid reader of reviews and articles about modifications of units, in particular i am very interested in dacs and line preamps.
I understand that some mods can elevate already good stock units to really high standards.
Have you any personal story about a mod of dacs or line preamps ending with very good results ?
Or any advice to give me ?
Thanks a lot.
Kind regards,
bg
Edits: 07/04/15 07/04/15 07/04/15Follow Ups:
I've done a lot of this, on amplifiers, line stages, and phono stages, because I am too lazy and too lacking in spare time to start from scratch. Before attempting anything beyond a parts "upgrade", it would be a good idea to educate oneself regarding circuit design and implementation, reading schematics, etc. If you're messing with tube gear, you can learn a lot by following TubeDIY and other such fora for a while, before you do anything yourself. There are some excellent texts that are written so as to be understood by the neophyte. Among these are: Bruce Rozenblitt's Amplifier book, in which he explains all the parts of an amplifier very simply, and shows you how to do some of the necessary math, which is not worse than algebra. Morgan Jones' books are best read AFTER one has digested a little info from simpler sources, but after that they are indispensable. (Sorry, I cannot off the cuff recall the titles of Bruce Rozenblitt's book or MJ's book, of which there are 3 editions.) Also good is Jon Broskie's blog, Tubecad. There are some guys on TubeDIY who are just good people willing to answer good questions on a one to one level, as well. Radiotron Designer's Handbook, Vols 1-4, which date back to the 30's, are a kind of bible for this stuff. Vol 4 is reproduced and can be purchased from Amazon or the like.
Hi and thanks a lot for the very kind and valuable reply.
Let me comment here below
" I've done a lot of this, on amplifiers, line stages, and phono stages, because I am too lazy and too lacking in spare time to start from scratch. "
The idea has started looking at the huge number of modification shops in the net. And also reading reviews about the stock models and the units after modifications.
Even the same manufacturers offer mods of their products, like in the case of Counterpoint equipment.
I think that a modification of an already decent unit can provide very nice sound.
" Before attempting anything beyond a parts "upgrade", it would be a good idea to educate oneself regarding circuit design and implementation, reading schematics, etc. If you're messing with tube gear, you can learn a lot by following TubeDIY and other such fora for a while, before you do anything yourself. There are some excellent texts that are written so as to be understood by the neophyte. Among these are: Bruce Rozenblitt's Amplifier book, in which he explains all the parts of an amplifier very simply, and shows you how to do some of the necessary math, which is not worse than algebra. Morgan Jones' books are best read AFTER one has digested a little info from simpler sources, but after that they are indispensable. (Sorry, I cannot off the cuff recall the titles of Bruce Rozenblitt's book or MJ's book, of which there are 3 editions.) Also good is Jon Broskie's blog, Tubecad. There are some guys on TubeDIY who are just good people willing to answer good questions on a one to one level, as well. Radiotron Designer's Handbook, Vols 1-4, which date back to the 30's, are a kind of bible for this stuff. Vol 4 is reproduced and can be purchased from Amazon or the like "
Thank you very much indeed for the very helpful advice.
I am not much a tube guy even if i have the strong feeling that is somewhat easier to get good sound from tubes than from transistors.
Still very nice sounding solid state units do exist.
Let's say that they are more challenging.
I have already got advice to look at:
1) grounding design
2) power supplies
3) signal coupling
4) volume control in case of preamps.
I am almost exclusively interested in dacs and preamps these days.
I liked many tube line preamps i listened to.
I prefer to put only one good tube in the signal path.
In the dac or in the preamp. Maybe i should reconsider tubes.
They seem to have a magic touch with digital.
They make digital sound more relaxed and pleasant.
Thanks a lot again.
Kind regards,
bg
I replaced the volume pot in my CAT preamp, with individual mono pots, eliminating the balance pot...why? Cuz the original pot has huge steps which combined with the CAT massive 26dB line stage gain made late nite listening challenging, one click down=too low, one click up=too high.
The new pots has 48 steps(verses 23 of the old), much easier to find the just right level for my late nite listening sessions.
Eliminating the balance pot made for a nice improvement in separation/soundstage width and other subtle gains in SQ.
Hi and thanks for the valuable advice.
I had a line stage with a gain of about 6 times (16 dB ?)
Way too much for the power amp.
The volume pot was a 10k attenuator ... i put a 10K resistor in series with its input and halved the max voltage out.
With the right combination of resistor and pot the gain can be reduced a lot indeed.
I believe a lot in the solution.
Kind regards,
bg
I tried using an attenuation circuit(series /parallel resisters)in front the pot but SQ took a hit.
Hi i see
I do not know the actual value of the Cat SL1 pot ... but if the pot is 250k for instance you could try a 200k high quality resistor in series with a 50k attenuator.
In this way the input signal voltage reaching the pot will be reduced by around 5 times ?
You could try with cheap but decent parts first (resistor and pot) and if you like the sound then buy something of very good.
Kind regards,
bg
Edits: 07/17/15 07/17/15
Once had dual mono stepped attenuators. Soured me on the concept maybe for life. Yes, 48 steps sounds about right. I may have gotten use to it if there were enough gradations in level.
I am a very non-techie kind of guy. I slept through my high school physics class, so I can barely tell you what a resistor does vs. a capacitor.
I've been an avid Audio Research linestage user since I got into the hobby many years ago. The first few were all stock units with NOS tubes. I had read many positive reviews with Steve Huntley of Great Northern Sound (GNSC). He recently closed shop and joined Resolution Audio. He used to work at Audio Research, so he is familiar with their design philosophies.
I bought an ARC LS-25 Mk I with GNSC reference level mods a while back. I can't honestly tell you what all the changes are even if I have it side-by-side with a stock unit except the obvious things like better capacitors and resistors were changed out as well as power supplies. But the sound was absolutely amazing. I had compared it (with stock powercords) at the time to a stock Ref 2 Mk II unit with $$$ Shunyata powercords. The Ref 2 won that round by a small margin, but many of the differences mentioned by listeners were similar to observations between the 6H30 tube vs. 6922s. The only thing I thought the Ref 2 did better was the larger scale of the soundstage and had better microdynamics. How much of that was due to the powercord, the tubes (I had Siemens 6922s in there), and warm up, I would never know as we've not do any other follow-up comparison.
I had recently upgraded to a Ref 2 Mk I with GNSC reference level mod. Although both are "reference level" mods. I can tell that the mods to the Ref 2 was much, much more sophisticated. I don't have a stock Ref 2 to do a side-by-side comparison as all my friends have since upgraded to Ref 3 and Ref 5s. But in my system, the difference I am hearing is much more than the results of that original test I conducted back then. I am hearing better layering depth-wise of the soundstage, much more texture, weight, and body to the sound. And I am not using any NOS tubes. All the tubes in there are either Russian or new stock tubes.
FrankC
Hi and thanks for the very interesting and telling story/experience.
So when mods are done smartly they can really elevate remarkably the performance of a unit, whit a decent one becoming good and a good one becomining very good indeed.
This is what i will try to do in the future, when i stop moving for my job.
Building from the scratch is too challenging for me.
I have a big admiration for people able to do that.
Sometimes the results are truly amazing.
I think that even vintage units can be a good basis for mods.
Thanks a lot again.
Kind regards,
bg
I suspect that a major part of the "mod" was really using better (more expensive) parts that had been "value-engineered" out to make the stock unit to meet certain price point. I did google those capacitors he put into my linestages and they are not cheap.
FrankC
Hi and thanks a lot again for the valuable advice
I believe completely in the benefits from using better parts
A friend of mine has a pair of BBC ls3/5a speakers
He built new xovers using same values but very top quality parts ...
He had to place the new xovers out of the cabinets because they were huge and did not fit inside.
the difference in sound with the original ( he modded one speaker at a time to compare) was very impressive indeed.
Thanks again.
Kind regards,
bg
Edits: 07/15/15
preamps are easy to mod: changing of coupling caps:updating power supplies; all tried and true techniques and very effective.
DACS/Cd players are more tedious and labor intensive. I normally cover each individual chip and transistor with ERS. A lot of jitter is being emitted by the digital chips which are all running at lightly different times and doing different functions.
Since most modern players are universal machines, DVD and Blue ray circuits add tremendous amounts of noise. You need to isolate them from the analog boards. A quick look at top line Sony's and Marantz units show a a shield over the video sections. If your machine does not have such shielding you can install your own, I use ERS for this too.
Front display panels also create a lot of digital noise. Again the top lne players will add a shield immediately behind the front panel
Hope this helps
Hi and thanks a lot indeed for the very helpful advice
I knew that dacs were more tricky to mod.
I like the idea of separate power supply for digital circuits and analog ones very much and i guess that most refined unit has this kind of solution. Dacs are my main interest these days.
But i like also line preamps.
Thanks again.
Kind regards,
bg
Well, I had a tube preamp kit that I bought. I assembled it and it was OK sounding. Then I bought some upgrade capacitors and got hold of some black gate electrolytics and just redid the preamp without really knowing what I was doing (you really just need to know how not to electrocute oneself, basically). It turned out really good sounding.However, as it was a circuit board kit, I found the chassis work really hard to do, and so it sits in a cardboard box, to be resurrected when I really get the time (and don't neglect the space a project requires).
Doing power supplies and changing capacitors is probably a worthwhile thing to try. It does save a lot of money if you get the upgrade bug.
Edits: 07/05/15
Hi and thanks a lot for your kind and very valuable reply.
This is exactly what i mean.
Taken a basically decent design i suspect that a smart replacement of critical parts can give a remarkable boost to overall performance.
To trivialize a little just replacing a electrolytic cap in series with a tweeter in a old pair of speakers changed the sound a lot for the better.
Everything improved remarkably.
I read an article extremely interesting.
A modder actually did not add anything to a cd or a dvd player i do not remember exactly. He just took out redundant parts.
The final sound was better. With less components.
Lately i have been focusing power supplies. They are very fundamental.
I am using a small but nice usb headphone amp from Breeze Audio. Extremely cheap.
The sound was ok using the power supply from the pc, usually weak and dirty.
Then i tried a usb power supply from Teradak. No doubt. Much better.
Less noise more dynamic more detail more ambience.
This is just a merit of the improved power supply.
So for now PS are my love. And nightmare.
Of course component in series with the signal are even more decisive for good sound.
Thanks a lot again.
Kind regards,
bg
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