| Nuuk |
I seem to be thinking of nothing else but Gainclones these days :dead:
My latest thought is to wonder how beneficial it may be to have the pot/attenuator as close as possible to the chip in an inverted GC design?
Anybody got any thoughts on this? |
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| rocktboy |
my related question is how much "harm" if any, is to have the pot further away from the chip? since i don't plan on using a connecting rod like peter's commercial product I am likely to move my pot to the front panel instead of it's current position at the rear panel. Also, should I have the input cap and resistor close to the pot or close to the chip? :confused:
thanks,
Jack |
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| JOE DIRT® |
the shortest path is always the best in most cases but I dont think 6 inches of sheilded wire is going to make any kind of sonic difference in the audio spectrum.....in RF design this could create problems
DIRT® |
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| tiroth |
It depends. I built a proof-of-concept gainclone and was not happy with that 6" of lead. I was using a 100K pot. With that much resistance it is a problem waiting to happen, in my opinion, but it all depends on where you live, shielding, # of computers in your house, etc.
I built a couple others with <1.5" leads and was much more pleased. |
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| Peter Daniel |
| quote: | Originally posted by Nuuk
I seem to be thinking of nothing else but Gainclones these days :dead:
My latest thought is to wonder how beneficial it may be to have the pot/attenuator as close as possible to the chip in an inverted GC design?
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When I was working on the design of my GC, the main idea was to eliminate any wiring inside the amp completely so I could only hear the parts. My recent experiments indicated that the 2' of PS cable introduced it's sonic signature. In one of my amps, I also tried to use solid core silver wire for p2p connection (3 pcs 2" long and used for grounding) and I also heard the difference between the amp using silver wire and the amp with copper wire.
So my answer is that it will probably be detectable if you use a wire to connect potentiometer or place it very close to the chip. It's not also that hard to do as you can use extention shaft. |
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| ronc |
My latest cab design will have pot positioned around .5 inches from pin#8. The cab is 8x5x3" (golden ratio)and the H/S s are mounted vertical in silicone filled groves.The only drawback i can see at this time is the 3" length from the input to the channel selector then another .5" to the pot(which is the grounded version we have discussed).I have finally decided on the cab being solid oak .5" thk.as i cannot find any acrylic or lexan in the color(gloss black) that i want.
And YES Nuuk the pot pins will be attached LOL.Thanks for that tip man, i never thought about losing ground.
ron |
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| Peter Daniel |
| How far are PS caps from IC's pins?;) And may I suggest maple for the case. I think it sounds better than oak. |
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| Sandy H. |
Peter, I often see you commenting on the minutiae of audio nirvana. I honestly don't question your ears, but are you with sincerity saying a maple chassis would be better than oak? I am trying to learn and am still at the level that Black Gate vs. Panasonic is not an obvious choice, so I wonder is maple vs. oak more critical???
Seriously, I respect the opinion of the forum contributors, but I sometimes feel that you guys are joking.
With complete sincerity, is maple vs. oak a real concern. If
I missed the joke and am being the stooge for that, I understand. I really want to know, though. I just want to build some stuff that is quality.
Sandy. |
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| cowanrg |
| i am going to STRONGLY second the comments of sandy. |
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| JoeBob |
I'm doubting it was a joke, Peter seems rather serious abot such issues .There a many threads aurguing the validity of such claims, it's better not to start a new one out of this one.
As for the distance of the pot from the chip, think of this, is it important that the 10k resistor on the input be close to the chip? If you think so then you should place the pot close as well, because the pot is also in the feedback path and adds to the 10k value depending on it's position (anything but full volume) and acts i nthe same manner. As for if it makes an audible difference... Well, that's up to you... |
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| ronc |
I am using battery power, P/S caps are directly connected to the pins,6.8 uf.
ron
Any idea where to pick up gloss black acrylic or lexan?
thanks |
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| Peter Daniel |
I wasn't joking about using maple. Why I think about using that wood?
First of all, to me, maple looks nicer than oak, is harder and since my brother in law is in hardwood floor business, I know the wood a bit.:)
Then, I was reading some reviews in magazines and it was always commented how good maple is for stands (best example Pagode stands). Also, there must be a reason Sonus Faber is using maple for their speakers. I believe each type of wood has it's sonic signature and this can be heard.
Last thing, I just finished my speakers, where I used solid maple for all panels and I'm amazed with a sound.
I buy acrylic from a local supplier. If you don't have any other source available, I might buy for you, if you interested. You may try this thread too: http://www.diyaudio.com/forums/show...+to+buy+acrylic |
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| Bricolo |
| quote: | Originally posted by ron clarke
My latest cab design will have pot positioned around .5 inches from pin#8. The cab is 8x5x3" (golden ratio)and the H/S s are mounted vertical in silicone filled groves.The only drawback i can see at this time is the 3" length from the input to the channel selector then another .5" to the pot(which is the grounded version we have discussed).I have finally decided on the cab being solid oak .5" thk.as i cannot find any acrylic or lexan in the color(gloss black) that i want.
And YES Nuuk the pot pins will be attached LOL.Thanks for that tip man, i never thought about losing ground.
ron |
Do the golden ratios add something for an amplifier case? |
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| Nuuk |
| quote: | | So my answer is that it will probably be detectable if you use a wire to connect potentiometer or place it very close to the chip. It's not also that hard to do as you can use extention shaft. |
Hi Peter, my question arose after reading the review of your amp and looking closely at the design. I presume that close proximity of the volume control to the chip is the reason for using seperate volume controls for both channels, as well as keeping it all dual mono.
I have a design on paper for each channel to have it's own stepped attenuator with each attenuator next to the chip BUT with a single volume control! It's not particularly difficult to build (especially for somebody with your skills) and seems to provide the optimum solution.
As regards the 'which type of wood sounds best' issue, I am sitting on the (balsa wood) fence.
Everything in an amplifier is connected in some way and is therefore affected by the total mass with its properties such as density and resonance.
The case is probably the biggest mass and will therefore (arguably) have the largest affect. So we can't dismiss the idea that the wood used for the case will have some affect on the sound of the amp but we should remember also that the circuit design, it's implementation and the component quality should (will) have a much larger influence, arguably enough to possibly swamp the effect of the case material.
Do you guys think that I would make a good politition? ;) |
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| Peter Daniel |
I believe that the material used for chassis has at least 25 % effect on the sound. And going with a lowest mass is probably not the best solution either. In my monoblocks the sound was simply unnaceptable, until I made some structural changes. And my acrylic version still doesn't sound as good as all aluminum amp.
If you check Niro amps from Mechanical Research Corporation, Nakamichi takes special care to decouple all the input connections (AC, RCA, binding posts) from the amp's chassis. There must be a definite reason for doing that.
http://216.87.12.168/enf/nirotek/ |
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| Nuuk |
I think that I may have said this before somewhere, but much of the 'black art' of hi-fi building is knowing the difference between damping, coupling and decoupling; particularly knowing when and where to use each technique!
Of course most of us build a project and then want to listen to it, not take it to pieces again and build it in a different case or whatever so this area is probably one of the least (properly) explored areas of DIY hi-fi (or commercial hi-fi for that matter).
I know of some 'proper' research in this area that has thrown up some surprising results but alas, it is not for public broadcast at present :bawling: |
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| ronc |
If you look at higher priced (ie. greater than 2k$ US amps) you will see greater attention to chassie build and materials.I have heard that about 33% of the final sound comes from the chassie matls. and design.
I still want to try either acrylic or lexan, but will go with a heavier wood first as a test.
ron |
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| ronc |
As i am primarly a speaker designer and builder i have used the golden ratio many times in my designs.It helps cut down on standing waves in an enclosure.
ron |
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| Bricolo |
| quote: | Originally posted by ron clarke
As i am primarly a speaker designer and builder i have used the golden ratio many times in my designs.It helps cut down on standing waves in an enclosure.
ron |
how do you calculate golden ratios?
I know the 0.618/1/1.618, but I've seen many others
Is there any algorythm? or rule of thumb? |
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| analog_sa |
| quote: | | believe that the material used for chassis has at least 25 % effect on the sound. And going with a lowest mass is probably not the best solution either. In my monoblocks the sound was simply unnaceptable, until I made some structural changes. And my acrylic version still doesn't sound as good as all aluminum amp. |
Peter
I have reached the conclusion that various effects on sound are not simply additive, they tend to change the sound in different directions. With supports and racks i have always prefered the light and rigid approach and was pleasantly surprised that my latest GC (very heavy) sounds good. That is without the top cover of course :)
I once saw the Niro open and was not impressed neither by the quality of the parts, nor by the general electrical construction (lots of cheap plastic connectors between the boards). It is certainly not a no-compromise design.
cheers |
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| Peter Daniel |
| As the name indicates, Niro is probably concentrating more on mechanical aspect of a design than electrical (Mechanical Research Corporation);) |
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