MaxS, you are quite right, I insist on perfect transient response (before application of input RC filter) and very high stability margin - rugged output stage tolerant to even high capacitive loading. Not that audio signals are that fast, but, for some reason, HF nonlinearity is a very bad thing for a good sound. Also, circuit designs based on integrators (dominant pole somewhere at 1 - 10Hz) are not the best sound choice.
Allen,
I understand your point. At th e end of the day, if the loading is switchable (and one of the positions has no loading R or C switched in), then its up to the listener to make the choice - this is what I am aiming for in my phono amp. If the user does not like the loading then use it without! Of course, 47k is the basic load.
I understand your point. At th e end of the day, if the loading is switchable (and one of the positions has no loading R or C switched in), then its up to the listener to make the choice - this is what I am aiming for in my phono amp. If the user does not like the loading then use it without! Of course, 47k is the basic load.
Relays are problematic, that is why I prefer silver-on-silver switches where possible. I think that good low level relays, used at line levels, can be pretty darn good, not virtually perfect, but pretty darn good. Very low voltage level relay operation could be problematic.
Yes, I agree a good switch is hard to beat from the straight performance point of view. I like relays for their convenience though.
Talking of switches, I am about to order a Goldpoint switch to use in place of an Alps Blue Velvet put - I'm looking forward to making some comparisons.
Talking of switches, I am about to order a Goldpoint switch to use in place of an Alps Blue Velvet put - I'm looking forward to making some comparisons.
transformers
Thanks Pavel !
Just asking because there are sometimes Talemas on ebay. I have 1000VA toroid, made in Czechia, C=1nF. It has good idle current: 24mA, even better than in spec (38mA).
My locally made toroid (300-400VA) has Io= 23mA, C= 870pF. It was made in old times when scerws were hammered in cause everybody beeing so hurry building some -ism
and it was hard to find suitable screwdriver.
But, for comparison I measured EI in my Sony TA-F707ES - C=240pF !
PMA said:
Thanks Pavel !
Just asking because there are sometimes Talemas on ebay. I have 1000VA toroid, made in Czechia, C=1nF. It has good idle current: 24mA, even better than in spec (38mA).
My locally made toroid (300-400VA) has Io= 23mA, C= 870pF. It was made in old times when scerws were hammered in cause everybody beeing so hurry building some -ism
and it was hard to find suitable screwdriver.
But, for comparison I measured EI in my Sony TA-F707ES - C=240pF !
We have made several listening sessions and comparisons, with audience. After tests against Parasound Halo JC-2, Audio Research SP-15, Audionet Pre G2; with Audionet AMP monoblocks as power amp for example, and Quadral Titan Mk IV as speaker for example, I can say that properly built and in-box wired Dispre II, with a good power supply, can compete IMHO to ANY high-end preamp.
PMA said:
Pavel, sincere congrats !
BTW, do you have a plan to make later also the components values with pow supply and wiring public ?
PMA said:
...That is why i'm waiting for the 3rd Gb for the boards....😉
...call me biased but i got a great one already...UGS, will build this one when PMA sells me the Boards ....and i have a long time wish to build a Douglas Self one ( also waiting for the boards )....would make a interesting set for comparison...no ?
What were you expecting? Were you expecting that your design would sound terrible nex t to commercial products?
As an engineer, I would expect that you KNOW that good engineering delivers GOOD results.
So, I am not surprised that your pre-amp sounds good.
However, you can improve significantly the sound of your pre-amp:-
1. Start with a block of solid aluminium
2. Machine it out so that you can fit the transformers, PCB's and switches into their own purpose designed cavities
3. Use a decent 24 position attenuator - that Alps thing you are using is holding you back
4. Be sure to drive the attenuator with stepper motor - couple using a chain or rubber traction loop (careful: the chain may cause resonance efects)
5. You must be sure to tell everyone your design is 'Zero Global Feedback Enabled' (ZGFE [tm])
6. Then, trash everyone else's efforts and claim yours is no. 1 in sound
NB - do NOT use any form of controller. Housing any form of MCU near sacred audio circuitry is sacrilage. When no one is looking though, sneak one in! You can always claim your solid machined aluminium housing overcomes any EMI or sound degradation caused by the MCU clock signal and I/O port noise.
As an engineer, I would expect that you KNOW that good engineering delivers GOOD results.
So, I am not surprised that your pre-amp sounds good.
However, you can improve significantly the sound of your pre-amp:-
1. Start with a block of solid aluminium
2. Machine it out so that you can fit the transformers, PCB's and switches into their own purpose designed cavities
3. Use a decent 24 position attenuator - that Alps thing you are using is holding you back
4. Be sure to drive the attenuator with stepper motor - couple using a chain or rubber traction loop (careful: the chain may cause resonance efects)
5. You must be sure to tell everyone your design is 'Zero Global Feedback Enabled' (ZGFE [tm])
6. Then, trash everyone else's efforts and claim yours is no. 1 in sound
NB - do NOT use any form of controller. Housing any form of MCU near sacred audio circuitry is sacrilage. When no one is looking though, sneak one in! You can always claim your solid machined aluminium housing overcomes any EMI or sound degradation caused by the MCU clock signal and I/O port noise.
Bonsai said:
😉 😉 what else matters ? Bonsai ?
But coming from PMA...I want to build one. 🙂
joking aside....cause sound is what it's all about.
Once we get used to hearing same equipment over and over we get biased...to be true we need to listen to credible proposals....and PMA is certainly that.
Congratulations Pavel, thought it would sound excellent 🙂 ...
Bonsai, amazing comments. Simply amazing? 🙂 ...
Bonsai, amazing comments. Simply amazing? 🙂 ...
😀 😀 😀
No hard feelingss Pavel - I do believe your Dispre probably sounds awsome.
🙂
I'm wiring my pre-amp up now. I'll post some photos maybe in a few days.
No hard feelingss Pavel - I do believe your Dispre probably sounds awsome.
🙂
I'm wiring my pre-amp up now. I'll post some photos maybe in a few days.
Bonsai said:
It does, as the signal is so minute that the changes in the relatively massive..er... mass (in comparison) of the devices vs the signal make it so that the last place one would want to have any extra components that are even remotely 'suspect' is in a phono circuit. We're getting down to clearly sonically observable molecular issues interacting with this minute signal. Iifffin' the rest of the system, including the brain wiring/learned of the listener are up to the task, that is.
We are also dealing with a situation where we talk about the PEAK output of the cartridge but the reality is that we are talking about the most subtle shadings and minute changes in the most minute components of this minute signal, so changing just the humidity alone anywhere near the circuit can have a noticeable effect that can be (comparatively) heard.
Commercially released designs have a need to allow for loading but the DIY folks can hardwire it..hopefully in an intelligent manner. An intelligent designer allows for the cleanest path with that possibility for changing the loading. The nature of it is that many times the best loading design can be a bear for the consumer to deal with.
Individually placed resistors in a specific set of sockets that are of the right design is the best compromise that I've been able to make it to, with regards to variables in the circuit path at such a delicate point as an MC input.
The truth tends to be that some of the most awkward to use designs have a tendency to sound the best, as the compromise level is at it's lowest point. The tree that bends in the breeze at that point is the long suffering audiophile who is only searching for the best that they can sonically achieve.
KBK said:
You are in fact addressing to PMA.
http://www.diyaudio.com/forums/showthread.php?postid=1647971#post1647971
I can't say anything else about your message 'cause the "clearly sonically observable molecular issues interacting with this minute signal" doesn't make any sense to me. But I'm sure PMA will understand. Though, I fully agree with Bonsai here: http://www.diyaudio.com/forums/showthread.php?postid=1648634#post1648634 Series contact/relays at the phono amp input are a big nono. But a parallel contact, switching the MC/MM input impedance, has absolutely no impact. Reason is that assuming the same noise mechanism as in a resistor (or even ten times worse) the contact contributes to the noise not more than it's contribution to the switched resistor. Which is, for all practical means, zero.
Nelson's Xono (anybody around thinks this is a poor phono preamp, at least when it comes to noise?) uses rocker DIP switches to switch the R/C at the MC/MM input (see the picture in the Xono manual).
On the other hand, Kevin talks so pretty that one does not really care what it exactly is he's saying.
