Tube amp vs Solid State ouputs?

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  • heiney9
    heiney9 Posts: 25,165
    edited August 2009
    The 750 is very close to being the Aleph P, it's completely based on it. They did some cost cutting is some area's but it is an outstanding pre. Here are a couple interesting threads about the 750. Take the first one with a grain of salt as it's just one modders opinion.

    http://www.head-fi.org/forums/f6/adcom-gfp-750-diy-mod-finally-finished-warning-not-dial-up-friendly-loads-pics-392211/

    This is the thread from DIY audio......................very, very informative.

    http://www.diyaudio.com/forums/showthread.php?s=&threadid=37960&highlight=
    "Appreciation of audio is a completely subjective human experience. Measurements can provide a measure of insight, but are no substitute for human judgment. Why are we looking to reduce a subjective experience to objective criteria anyway? The subtleties of music and audio reproduction are for those who appreciate it. Differentiation by numbers is for those who do not".--Nelson Pass Pass Labs XA25 | EE Avant Pre | EE Mini Max Supreme DAC | MIT Shotgun S1 | Pangea AC14SE MKII | Legend L600 | BlueSound Node 3 - Tubes add soul!
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  • Systems
    Systems Posts: 14,873
    edited August 2009
    Mega,if you are interested in hearing a BOZ vs your FET1 ,I can send you one for an audition.
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  • Systems
    Systems Posts: 14,873
    edited August 2009
    wrote:

    http://www.head-fi.org/forums/f6/adcom-gfp-750-diy-mod-finally-finished-warning-not-dial-up-friendly-loads-pics-392211/
    I'm not sure of the brand of those blue caps used for input and output coupling but I would want to replace them.I believe the Aleph P used the Panasonic ECQ's.
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  • megasat16
    megasat16 Posts: 3,521
    edited August 2009
    GV#27 wrote: »
    Mega,if you are interested in hearing a BOZ vs your FET1 ,I can send you one for an audition.

    Wow! What an Awesome Offer. ;) I am seriously thinking about it but I am thinking potential risk from shipping to and from Canada and Cali. :)
    Trying out Different Audio Cables is a Religious Affair. You don't discuss it with anyone. :redface::biggrin:
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  • megasat16
    megasat16 Posts: 3,521
    edited August 2009
    GV#27 wrote: »
    The Aleph P and 750 have the same basic gain stages(differential pair of Mosfets) based on the DIY Bride of the Son of Zen pre, which is the balanced version of the single ended Bride of ZEN.One would expect the there to be a strong family resemlence between them.I have built two Bride of ZEN's and think it a great sounding little pre.

    Thanks again for chiming in! ;) I also think the family resemblance between Aleph P, Threshold FET Pre, Adcom GFP750 and Nak CA-5/CA-7 pre. From what I can see, Pass had got rid of Tone Control in the Threshold FET in the the mid 80s where it was very popular among many other brands. But I am not missing it.
    heiney9 wrote: »
    The 750 is very close to being the Aleph P, it's completely based on it. They did some cost cutting is some area's but it is an outstanding pre. Here are a couple interesting threads about the 750. Take the first one with a grain of salt as it's just one modders opinion.

    http://www.head-fi.org/forums/f6/adcom-gfp-750-diy-mod-finally-finished-warning-not-dial-up-friendly-loads-pics-392211/

    This is the thread from DIY audio......................very, very informative.

    http://www.diyaudio.com/forums/showthread.php?s=&threadid=37960&highlight=

    Thanks H9 for the linky! ;) How are you liking your new GainClone? :)
    Trying out Different Audio Cables is a Religious Affair. You don't discuss it with anyone. :redface::biggrin:
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  • madmax
    madmax Posts: 12,434
    edited August 2009
    megasat16 wrote: »
    It's possible to use filter caps close to each output transistors for the amps with less than 2-4 transistors for each channel. Remember you'll need a trace for (source in MOSFET and collector in BJT) for each transistor. So, if you have multiple transistors in one channel, designing a PCB with a trace for each transistor could be a nightmare.

    If a substantial voltage drop during high dynamic power driving low impedance load is the primary concern for an amp, it should have fully regulated Power Supply Section which itself is a power amplifier. :) But remember, nothing is bullet proof in the audio amplifier. With enough time provided, any good amp will give up driving a hard load at a very loud volume. I guess the hearing will probably give up way before though. :D

    I see you are still not getting the idea. Maybe re-read what I said if you are interested. If not, just move on. Its a clever idea he is talking about.
    madmax
    Vinyl, the final frontier...

    Avantgarde horns, 300b tubes, thats the kinda crap I want... :D
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  • megasat16
    megasat16 Posts: 3,521
    edited August 2009
    madmax wrote: »
    I see you are still not getting the idea. Maybe re-read what I said if you are interested. If not, just move on. Its a clever idea he is talking about.
    madmax

    Honestly, I may got the wrong idea. I did re-read and I came to the same conclusion. It's a clever idea for an amplifier with small number of output transistors. But for an amplifier with large amount of output transistors, I couldn't imagine. May be coz I didn't get the point before and still not getting it after re-reading your post and RT1 post. So, I decided to move on and left it till better explanation comes along the way.
    Trying out Different Audio Cables is a Religious Affair. You don't discuss it with anyone. :redface::biggrin:
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  • Systems
    Systems Posts: 14,873
    edited August 2009
    madmax wrote: »
    I see you are still not getting the idea. Maybe re-read what I said if you are interested. If not, just move on. Its a clever idea he is talking about.
    madmax
    It is advantagous to have the filter capacitance reservoir close to the circuit it feeds( ie.output stage) and a number of designers do this.Also Having multiple smaller caps (vs a single large one) in parallel will result in a lowered ESR.
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  • megasat16
    megasat16 Posts: 3,521
    edited August 2009
    GV#27 wrote: »
    It is advantagous to have the filter capacitance resivour close to the circuit it feeds( ie.output stage) and a number of designers do this.Also Having multiple smaller caps in parrallel will result in a lowered ESR.

    This is not the same thing as what the new method of utilizing smaller caps. That's why I am not getting it yet.
    madmax wrote: »
    I'm thinking RT1 found something new here. The old idea was to bank them up to save money. What RT1 is saying is to seperate into individual caps right at the entrance to each output transistor. What this would do is to keep trace (or wire) losses from lowering voltages on big dynamic hits to the supply. For example, a cap right at the output transistor can deliver all of the stored charge when called for while keeping trace losses only pertinent to charging the caps back up. Great idea, better dynamic performance while being the same price as a bank or cheaper than a big cap! One more thing to add to my bag of tricks. :)

    madmax
    Trying out Different Audio Cables is a Religious Affair. You don't discuss it with anyone. :redface::biggrin:
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  • Systems
    Systems Posts: 14,873
    edited August 2009
    megasat16 wrote: »
    This is not the same thing as what the new method of utilizing smaller caps. That's why I am not getting it yet.
    I think the gist of his post was that having the capacitance close to the circuit it is feeding is benificial.With opamp circuits decoupling caps are often placed very close to the chip's body to reduce the effects of circuit trace inductance and resistance.
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  • megasat16
    megasat16 Posts: 3,521
    edited August 2009
    GV#27 wrote: »
    It might be something to do with the faster charge/discharge rates of the smaller caps.

    True with smaller caps. But each cap for each transistor? I am trying to picture 14 small caps near 14 output transistors. Also, more parts, more chance of failure. Mounted Near the Power Transistors? Higher Rate of failure due to thermal aging. Even if it's possible to have 14 traces for collector / source on the PCB, I will take a little higher ESR over it. :)
    Trying out Different Audio Cables is a Religious Affair. You don't discuss it with anyone. :redface::biggrin:
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  • Systems
    Systems Posts: 14,873
    edited August 2009
    megasat16 wrote: »
    But each cap for each transistor?
    Thats abit extreme and have never seen such a thing done to that extent.Most will have some local decoupling of some sort with a main filter cap bank feeding them.I have seen a number of designs that have had the main filter cap bank placed very close to the output stage.Interconnection to the supply was via short heavy guage wire and or wide PC board traces.
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  • madmax
    madmax Posts: 12,434
    edited August 2009
    Thats fine. Just to redefine the idea since I think its a cool one :). Suppose you had an amp with 16 FETS, 8 per channel, and wanted your supply to have two 16000 uF caps, one for the positive supply, the other for the negative supply. Three ways you could go. 1: Two 16000 uF caps at the end of the supply. 2: Sixteen 1000uF caps wired in a bank at the end of the supply (to save money). 3: Sixteen 1000uF caps, each one located right next to the source of each FET effectively removing any resistance between the supply and the fets (as opposed to having long wiring or traces with maybe 0.1 ohms). This could easily give you about and extra .8 V on your FET sources when driving a 4 ohm load for an extra 8 watts output per FET (128W when multiplied by the 16 FETS) during a peak. Of course this doesn't doesn't give you squat for extra average power, only the peaks since you still have to wait for the caps to charge back up. Not a shabby gain given you've saved money by using seperate caps and didn't spend anything extra on the transformer. Sorry, I just get into getting something for nothing. Just too cool not to do. :)
    Vinyl, the final frontier...

    Avantgarde horns, 300b tubes, thats the kinda crap I want... :D
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  • megasat16
    megasat16 Posts: 3,521
    edited August 2009
    Thanks for caring to explain further, Max! It's making sense to me. It's extreme design as GV said. And it's too cool not to do it. :) Sorry I derailed this thread with my BS.
    Trying out Different Audio Cables is a Religious Affair. You don't discuss it with anyone. :redface::biggrin:
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