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Thread: OT: SET amps for Altec compression drivers

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    Hostboard Member xinu's Avatar
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    OT: SET amps for Altec compression drivers

    I?ve played thru a few simple design old school single ended tube guitar amps. IMO they can have a sweet clean tone that responds well to pick dynamics with a satisfying sheen to the notes. I?m thinking a SE type tube circuit might sound very good driving my Santiago?s 806s.

    Obviously HiFi amps have a different design intent but I?ve been reading about how simple low power SE amps could couple nicely with high sensitivity horn loaded drivers.

    I grabbed this from another thread which has got me thinking more about using single ended tube amps to drive my HF:

    Quote Originally Posted by GM View Post
    True, but compression horns want to 'feel' a matching impedance, so 2a3, 300b or similar SET tube amp for the HF, class A or A/B SS if at least the 1st 10 W is class A is about the best one can hope for without resorting to a monster low output impedance tube amp in its own Frigidaire for the woofer.

    GM
    Would a SE tube amp without negative feedback provide a better impedance match for compression horns? Or does it matter as long as it?s class A? I?m asking to determine if I should focus on SE amps without NFB.

    I would be interested to know if anyone has used reasonably priced SE triode/pentode amps with Altecs and did they live up to your expectations.


    Thanks,

    Greg

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    Senior Hostboard Member LowOhms's Avatar
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    Re: OT: SET amps for Altec compression drivers

    Quote Originally Posted by xinu View Post
    I?ve played thru a few simple design old school single ended tube guitar amps. IMO they can have a sweet clean tone that responds well to pick dynamics with a satisfying sheen to the notes. I?m thinking a SE type tube circuit might sound very good driving my Santiago?s 806s.

    Obviously HiFi amps have a different design intent but I?ve been reading about how simple low power SE amps could couple nicely with high sensitivity horn loaded drivers.

    I grabbed this from another thread which has got me thinking more about using single ended tube amps to drive my HF:



    Would a SE tube amp without negative feedback provide a better impedance match for compression horns? Or does it matter as long as it?s class A? I?m asking to determine if I should focus on SE amps without NFB.

    I would be interested to know if anyone has used reasonably priced SE triode/pentode amps with Altecs and did they live up to your expectations.


    Thanks,

    Greg

    Greg,

    You should just get a 98 dB ALTEC speaker, a 604 or a VOTT, and run it with ONE really good SET 2A3 amp per speaker.

    If you get the ALTEC speaker model correct, I will show you how to build an amp for it. All else, is second fiddle, and IMHO, a waste of one 's time, money, efforts, and life.

    Jeff Medwin

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    Hostboard Member xinu's Avatar
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    Re: OT: SET amps for Altec compression drivers

    Well Jeff, I get it. My speakers just won’t do. No point wasting anymore of my time and money.

    On second thought, I really don’t mind second fiddle so long as I get to play and maybe with enough practice, I'll be fiddling first one day.

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    Senior Hostboard Member Elitopus1's Avatar
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    Re: OT: SET amps for Altec compression drivers

    Quote Originally Posted by xinu View Post
    I?ve played thru a few simple design old school single ended tube guitar amps. IMO they can have a sweet clean tone that responds well to pick dynamics with a satisfying sheen to the notes. I?m thinking a SE type tube circuit might sound very good driving my Santiago?s 806s.

    Obviously HiFi amps have a different design intent but I?ve been reading about how simple low power SE amps could couple nicely with high sensitivity horn loaded drivers.

    I grabbed this from another thread which has got me thinking more about using single ended tube amps to drive my HF:



    Would a SE tube amp without negative feedback provide a better impedance match for compression horns? Or does it matter as long as it?s class A? I?m asking to determine if I should focus on SE amps without NFB.

    I would be interested to know if anyone has used reasonably priced SE triode/pentode amps with Altecs and did they live up to your expectations.


    Thanks,

    Greg
    I have a friend who runs the biamped setup using tubes for the HF and SS for the woofers. It sounds damn good. I'll have to ask him what kind of amp he is running. I know its SE EL84 but I am not sure about the NFB or not.
    For someone who wants to use an active crossover I would highly recommened this setup. Horns sounds so nice with a tube amp. And the woofers benefit from the extra power of a SS amp.

    You could grab a cheap console tube amp for around 100 bucks if you wanted to try it out on the cheap. Also there are some cheap active xovers. Or just split up the passive xovers with two sections, with different inputs.

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    Senior Hostboard Member LowOhms's Avatar
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    Re: OT: SET amps for Altec compression drivers

    Quote Originally Posted by xinu View Post
    Well Jeff, I get it. My speakers just won’t do. No point wasting anymore of my time and money.

    On second thought, I really don’t mind second fiddle so long as I get to play and maybe with enough practice, I'll be fiddling first one day.

    Right Greg,

    I was not criticizing YOU in any way.

    But I see me in " you " from my own audio experience, a HUGE round-trip, from Dad's ALTEC 604Bs in my family's basement rec room, Trenton, N.J., when I was a boy...to....

    A multitude of other speakers, and after six decades, I end-up finding that a 604 or a VOTT, " well implemented ", was all I needed.

    Maybe, for me to LEARN what is " well implemented ", was the 60 year time / price I had to pay. It has taken me a LOT of time, and a LOT of systems, to get where I wanna be !!! I need at least three more months to get my VOTTs where I want them to be.
    \
    In November 2016, I built a lovely dual mono JJ 2A3-40 amp, direct-coupled, finished 12-01-2016, and took it apart on 1-4-17, after deciding that two MONOBLOCKS, with what I know, same circuit, will get me an incrementally better-sounding lay out!!

    Besides needing to build these monoblock JJ 2A3-40 SETs, I also am going to build a high quality Attenuator, to control the system volume, that build also scheduled.... Q1, 2017. Will be busy.

    Greg, look at this following " laundry list " of speakers I went through, to get BACK to a simple ALTEC two-way VOTT A7-800 in recent times.

    a) 604B, as a child, Dad's.
    b) Tannoy 15 inch co-axial Monitor Golds, in GRF enclosures, outta college, first year.
    c) KLH-9s ESLs, single pair
    d) KLH-9s, double pair
    e) QUAD ESL Type 57, one pair, briefly
    f) Infinity Servo Static !s, with all 1-A components
    g) Fulton FMI-80s
    h) Fulton Premiere ( seven way 12 HZ to 110.000 HZ, measured plus or minus one dB. )
    i) Klipsch La Scala, modded the box, 1.5 inch thickness
    J) RCA Ubangie bass horns, and MI-1428 Field coil compression drivers, large-scale movie theater stuff
    k) ALTEC VOTT A7-800s

    The above does NOT include ALL the amps I built and went through, the weak part of all the systems, for-sure, in my opinion.

    Now Greg, after spending a life-time of thought, energy and money, on audio, on all this gear, let me share with you these recent / true facts :

    a) I was GIVEN the ALTEC 515Bs
    b) I was GIVEN the 802Ds
    c) I was GIVEN the ALTEC horns ( traded them off )
    d) I was GIVEN The VOTT 825 enclosures

    ALL of the above, recently, for free, from two Audiophiles in my area. People, friends that I had tube-amp-mentored over the last 28 years. I think that is quite a story, a true one, and that it was " meant to be " - that I would come back to ALTEC, six full decades later.

    My parents both lived well into their 90s, and I am hoping I can do the same, sitting with A7-800s playing in my modest home.

    Sorry to bend your ear, I was just wanting to encourage you to at least ASPIRE..... to a 604 or VOTT, and spend time getting it really right.

    One other thing, I am working with new film cap types, costly, but I THINK its a huge break-through. Once I get things worked out with them, I will be glad to share this information, with whoever has such an interest.

    Right now, these caps are in ALL locations in my ( all-film-cap ) SET amplifier power supply filters, and, are in ALL locations in my ALTEC crossovers also. What is does is totally fabulous to hear.

    I may be the only person, hearng ALTECs, with these special amps, crossovers, employing this " break-through " part combination. Complete details forthcoming in a couple months...promise !!

    For the record Greg, my two favorite audio sayings are as follows:

    1) In the end, we all listen to a modulated power supply. How good is yours?

    2) An inch of bad wire, can ruin the musical experience.

    Have fun, call me some time, we can chew the fat and I can, unimpeded, fully explain to you why biamping in general, and especially with two different amp-types, is a less-than-desirable approach, really, only for the audio novices to employ.

    Jeff Medwin
    Last edited by LowOhms; January 27th, 2017 at 10:41 PM.

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    Senior Hostboard Member GM's Avatar
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    Re: OT: SET amps for Altec compression drivers

    Quote Originally Posted by xinu View Post
    Obviously HiFi amps have a different design intent.......

    Would a SE tube amp without negative feedback provide a better impedance match for compression horns? Or does it matter as long as it’s class A? I’m asking to determine if I should focus on SE amps without NFB.

    I would be interested to know if anyone has used reasonably priced SE triode/pentode amps with Altecs and did they live up to your expectations.
    Today's designs, yes, but the originals were SET until they invented P-P and relegated the SET to pre-amp duty.

    The amp's topology per se doesn't determine its output impedance, its coupling transformer does. You can wire one of today's SS amps to an outboard tranny and get a goodly portion of the tube era 'sound' [smiley face EQ]. Carver use to sell a SS amp that allowed a series resistor be switched into the circuit to do it and LCR filters are in common use to do it for both single driver speakers and called CD horn EQ for SS driven 'rising on axis' horns. The lure of tubes is the euphonic harmonic distortion it adds to a recording, etc., which some years ago was proven could be successfully mimic'd by inserting white noise into the recording loop to overcome the 'dry'/analytical sound of early digital recordings.


    Personally and probably due to having basically life-long tinnitus, I only prefer SET amps coupled to 'FR' speakers, but to accurately reproduce sound requires a flat amplitude and phase response, so Class A is the primary goal, though due to our generally so-so hearing acuity, a small amount [< DF = 20] is acceptable.


    All the SETs I've tried were reasonably priced because they came out of old radios, consoles, TVs, etc., back when consumers no longer wanted tubes. Today if I wanted a new one I guess I'd have to buy one of those Chinese kits sold on Alibaba that are so popular with the 'FR' speaker aficionados.


    The only other tube amps I've used are Mac MC60 that sounded too 'dark' and Mac 300B MC375 that I swapped out to make my first SS bi-amped compression horn system and have never looked back, though hindsight being 20-20, wish I'd kept the MC375 after seeing what it and the retro one sells for nowadays.


    GM



    - - - Updated - - -

    Quote Originally Posted by Elitopus1 View Post
    And the woofers benefit from the extra power of a SS amp.

    Or just split up the passive xovers with two sections, with different inputs.
    Yes, though the main reason is its high DF gives it much better control over the driver and much more flexible tuning options, i.e. its T/S specs dominate.

    It's desirable for the tube/horn to be passive and digital for SS, though of course it's fine if converting an existing speaker.

    GM

    - - - Updated - - -

    Quote Originally Posted by LowOhms View Post
    You should just get a 98 dB ALTEC speaker, a 604 or a VOTT, and run it with ONE really good SET 2A3 amp per speaker.

    If you get the ALTEC speaker model correct, I will show you how to build an amp for it. All else, is second fiddle, and IMHO, a waste of one 's time, money, efforts, and life.

    Jeff Medwin
    Hmm, we all hear the same, yet not so much, so imagine there's others with a similar mindset, but to me it's like claiming that aspiring to whatever technology designed after the mid 1940s is 'a waste of one 's time, money, efforts, and life' for the rest of us, which definitely doesn't work for me.

    GM

    - - - Updated - - -

    Quote Originally Posted by LowOhms View Post
    Right now, these caps are in ALL locations in my ( all-film-cap ) SET amplifier power supply filters, and, are in ALL locations in my ALTEC crossovers also. What is does is totally fabulous to hear.
    In your [not so humble] opinion. Again, we all hear the same, yet not so much, not to mention virtually all rooms 'color' a speaker's performance to a greater or lesser extent, making such 'absolute' statements about what we should be doing/using is just hearsay at best unless one can prove it more accurately reproduces the signal at least in theory.

    GM
    Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.

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    Senior Hostboard Member BillWojo's Avatar
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    Re: OT: SET amps for Altec compression drivers

    Sounds like I'll have to try my Dennis Had FireBottle SET amp on my Altecs. I really like this amp with my vintage Mullard EL34's.
    LowOhms, have you tried this combination yet? Dennis was the founder of Carey and is a superb amp designer.

    BillWojo

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    OT: SET amps for Altec compression drivers


    Phil-G's Avatar
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    Re: OT: SET amps for Altec compression drivers

    All this newfangled stuff you guys come up with. sometimes you can't beat the good sound of beating on a rock with a stick.
    Sonic Barbarian

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    Hostboard Member xinu's Avatar
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    Re: OT: SET amps for Altec compression drivers

    Quote Originally Posted by Phil-G View Post
    All this newfangled stuff you guys come up with. sometimes you can't beat the good sound of beating on a rock with a stick.
    But, I'm sure you will agree, you must have a path of extremely low resistance between the stick and the rock

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    Senior Hostboard Member LowOhms's Avatar
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    Re: OT: SET amps for Altec compression drivers

    Quote Originally Posted by BillWojo View Post
    Sounds like I'll have to try my Dennis Had FireBottle SET amp on my Altecs. I really like this amp with my vintage Mullard EL34's.
    LowOhms, have you tried this combination yet? Dennis was the founder of Carey and is a superb amp designer.

    BillWojo
    Hi Bill,

    I could not find a schematic on the Fire Bottle, but from what I could see, I would "pass" on ever using an amp like that. Its just a middle-of-the-road commercial / consumer product, and no wheres good enough for my tastes in audio and , especially on an ALTEC speaker that I had to listen to.

    But Bill, I feel, 99 percent of the amps available, are TRASH, SET, tube, and solid state, .....commercial and for-sure, DIY.

    Most likely, the only solid state amp out there, made in the USA to own. is a Spectral DMA-200S.

    That Dennis HAD amp is NOT an SET, but rather a SEP, meaning a Pentode Finals tube. I prefer to hear a Directly Heated Triode tube - like the new JJ 2A3-40 - for the Finals tube. There is no substitute for the real thing, which is a DHT Finals tube..

    Secondly, I have RECENTLY learned to AVOID shared supply ( stereo amp, one supply,. shared Left - Right ) tube amps on ALTEC VOTTS, Its just not good enough. Less audible total-clarity, when the going gets tough / complex. So, I prefer dual mono on ALTECS, and I am rebuilding my 12-1-16 Dual Mono amp into TWO monoblocks this month, to gain even more.

    After building DHTs since 1982, with Robert W. Fulton initially mentoring me, I have come down to only ONE basic circuit that is the BEST solution for VOTTs and 604s. It is basically a updated variant of the classic 1929 Loftin-White DIRECT COUPLED two stage circuit, without the hum cancelling gizmos, and with what is a " modern" power supply, sometimes called a LSES or Low Stored Energy Supply. No tube amp can equal that result, on an ALTEC speaker, IMHO. It uses a mu of 100 driver tube, directly coupled to the grid of a 2A3. KISS rules !!

    There have been various small companies over the years, that build this circuit, Don Garber at Fi, Craig Uthus at Moth Audio, come to mind. But honestly, their implementations are KIDDIE STUFF in my experience, full of errors and a multitude of cost-compromises.. The best guy commercial, for a SET amp, or a GPA 604 MLTL solution, since 1989, has ALWAYS been Dennis Fraker of Serious Stereo in Montana, USA. In any amp shoot-out, his stuff easily comes out on top !!

    Likely, you are unaware of Dennis and Serious Stereo. I attended the Rocky Mountain Audio Fest in October 2016, and got a chance to volunteer, and help Dennis ( a personal friend for 3 decades ) RUN his room. His GPA-604 system got a FABULOUS review from Stereophile magazine reviewer: See it here:

    GO to the URL listed below :

    " 2016 RMAF, by Herb REICHERT "

    Scroll down the page, looking at PHOTOS,


    ( Write up starts, right after the ELAC report, with a picture of two of Dennis? RED monoblock Serious Stereo amps ):


    RMAF 2016: Sunday at the Show with Herb | Stereophile.com


    Yupper, it was just me, Dennis , and Reichert in that hotel room, when Herbert stopped by and listened. Cool to meet him !!


    Fortunately, I am able to build my own version of the circuit, and I LOVE the result on my VOTTS. Dennis advises me on all aspects of VOTT set up, wiring, placement, etc. He typically used eight VOTTs in many of the theaters he has owned. He was in the Movie Theater business, owned a company called Cinema Design, and has been an avid audiophile, all his life. Hes a great fellow and friend. Visit his web site and give him a phone call, ask him questions.

    Jeff Medwin


    PS, Bill, there was one other Herb Reichert mention - about the Denver October RMAF Show and Dennis, scroll down till you get to " Favorite Rooms " .....see URL below, its the third paragraph after " Favorite Rooms " sub-heading, just two sentences:

    RMAF 2016: An Assessment | Stereophile.com
    Last edited by LowOhms; January 28th, 2017 at 01:39 PM.

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