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  1. #101
    Music Junkie E-Stat's Avatar
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    Quote Originally Posted by Sir Terrence the Terrible
    Another reason tubes amps are not used is they cannot stand the rigor and punishment of being used 12-15 hours a day being pushed to high levels on occasion. They just do not have the stamina.
    Such is an utterly ridiculous statement that ignores the first forty years of their use in ALL aspects of radio transmission and recording. Yes, they do generate lots of heat and require retubing which can be expensive.

    rw

  2. #102
    Ajani
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    Quote Originally Posted by Feanor
    Yes, briefly a few years ago with my Magneplanar MMGs. The character of the SM-70 Pro sound was identical to a pair used as balanced monoblocks, only the dynamics weren't as good, especially at higher volumes of course. Bear in mind that used as a stereo amp, the power is only 40 wpc into 8 ohms, (vs. 120 wpc into 4 ohms as a monoblock), so it is hardly more powerful that a typical tube amp.
    Thanks... I wouldn't need the extra power as I have the Emotiva to handle any heavy lifting... I was more thinking of a SM-70 Pro for use in my eventual 2nd system (or maybe my main if I find I prefer its sound to the XPA-2).... So knowing that all I would lose by using the SM-70 Pro as a stereo amp is power/dynamics is fine...
    Last edited by Ajani; 04-13-2010 at 12:45 PM.

  3. #103
    Shostakovich fan Feanor's Avatar
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    Quote Originally Posted by Ajani
    Thanks... I wouldn't need the extra power as I have the Emotiva to handle any hard lifting... I was more thinking of a SM-70 Pro for use in my eventual 2nd system (or maybe my main if I find I prefer its sound to the XPA-2).... So knowing that all I would lose by using the SM-70 Pro as a stereo amp is power/dynamics is fine...
    I need to correct myself. According to the Monarchy webside, (here), the SM-70 Pro specs for power are these:
    Power Output:
    Stereo Mode: 8 Ohm Load: 25 Watts rms x 2
    4 Ohm Load: 40 Watts rms x 2
    Mono Mode: 8 Ohm Load: 80 Watts rms
    4 Ohm Load: 120 Watts rms
    So it is evident that this amp is really designed as a momoblock. But note that each unit has 60,000 uF capacitance which is huge for the power output, consequently the dynamics are really good to which I can atest.

    Here is a Soundstage review of the SM-79 Pros. Quote from that review, "If the Monarchy SM-70 Pros have taught me one unexpected lesson, it is that the swing from silence to a full-blown crescendo is far greater than we normally settle for, even in ambitious systems -- and that's something the SM-70s re-create in their balanced configuration better than any number of ordinary amplifiers."

  4. #104
    Music Junkie E-Stat's Avatar
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    Quote Originally Posted by Feanor
    But note that each unit has 60,000 uF capacitance which is huge for the power output...
    Yes and no. Power supply stiffness as measured in joules is determined by multiplying the capacitance by the square of the rail voltage divided by 2. While 60,000 uF per amp is relatively high, the rail voltage is only 24 volts yielding a total of just under 35 joules for 60 watts / channel output (8 ohms) for a bridged pair of amps. Which is identical in voltage and capacitance to the power supply found in the 15 watt / channel First Watt F3. My '81 Stasis 3 has 90 joules for 100 watts / channel output (50,000 uF @ 60 v) and the VTL MB-450s have 500 joules (3,300 uF @ 550 v) for 300 watts / channel output. Truly heroic amps like the 600 watt / channel VTL Siegfrieds have 1500 joules while the Audio Research 600Ts have 2000 joules.

    SM-70s

    rw

  5. #105
    Shostakovich fan Feanor's Avatar
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    Quote Originally Posted by E-Stat
    Yes and no. Power supply stiffness as measured in joules is determined by multiplying the capacitance by the square of the rail voltage divided by 2. While 60,000 uF per amp is relatively high, the rail voltage is only 24 volts yielding a total of just under 35 joules for 60 watts / channel output (8 ohms) for a bridged pair of amps. Which is identical in voltage and capacitance to the power supply found in the 15 watt / channel First Watt F3. My '81 Stasis 3 has 90 joules for 100 watts / channel output (50,000 uF @ 60 v) and the VTL MB-450s have 500 joules (3,300 uF @ 550 v) for 300 watts / channel output. Truly heroic amps like the 600 watt / channel VTL Siegfrieds have 1500 joules while the Audio Research 600Ts have 2000 joules.

    SM-70s

    rw
    Thanks for that technical information that I'm glad to learn.

    I note that the Audio Electronics review you reference discussed the SM-70 not the SM-70 Pro which was significantly upgraded over the former. I can't find a reference to the latter's output rail voltage, however Gary Gallo, in a follow-up Pro review stated the raw rails were +- 32 VDC.

    In any case it's not entirely fair to compare the modestly priced SM-70 Pro with much more expensive equipment.
    Last edited by Feanor; 04-14-2010 at 05:31 AM.

  6. #106
    Music Junkie E-Stat's Avatar
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    Quote Originally Posted by Feanor
    In any case it's not entirely fair to compare the modestly priced SM-70 Pro with much more expensive equipment.
    Changing the rail voltage would require using completely different outputs. I suspect the upgrades were in the passive components. I was responding to the unqualified "huge" adjective. It is definitely stiffer than you would find on most consumer amplifiers and receivers, but not exceptional. There was an earlier thread about a McIntosh 2105 where someone commented on the large capacitors used in its power supply. Similarly, the Mac runs fairly modest rails for a good, but not extraordinary result (35v, 78000uF ~ 50 joules). The rail voltage has a far greater impact than the capacitance.

    rw
    Last edited by E-Stat; 04-14-2010 at 05:38 AM.

  7. #107
    Vinyl Fundamentalist Forums Moderator poppachubby's Avatar
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    Ralph did you see my post at the Vintage Asylum? I was hoping you would comment here or at AA, what are your thoughts about EICO gear and more specifically the HF 85 pre amp. I got one for a steal and it sounds lovely. Tommy didn't know too much. Mike Samra at AA helped me out with the sale, so I pounced.

  8. #108
    Music Junkie E-Stat's Avatar
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    Quote Originally Posted by poppachubby
    what are your thoughts about EICO gear and more specifically the HF 85 pre amp.
    Sorry for not responding. EICO is a venerable brand which produced some fine gear. I would consider them in the same favorable light as Dynaco who also offered kits. I think the preamp I owned some time ago was a HF-85. It had nice sound and I ended up giving it to a girlfriend. Back in my teens, I had fun building two Dyna kits. Great bang for the buck!

    Speaking of power supplies, the first thing that Frank Van Alstine did with any Dyna product was to substantially beef up the power supply. I had the FET-5 upgrade to a PAT-5 back in the 70s.

    rw

  9. #109
    Shostakovich fan Feanor's Avatar
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    Quote Originally Posted by E-Stat
    I was responding to the unqualified "huge" adjective. It is definitely stiffer than you would find on most consumer amplifiers and receivers, but not exceptional. There was an earlier thread about a McIntosh 2105 where someone commented on the large capacitors used in its power supply. Similarly, the Mac runs fairly modest rails for a good, but not extraordinary result (35v, 78000uF ~ 50 joules). The rail voltage has a far greater impact than the capacitance.

    rw
    I do understand that the rail voltage is the primary determinent of output power. I also understand that there is the opinion that "excessive" capacitance is worthless anyway.

    So of course I was comparing the SM-70 Pro to other amps in its price range, (<$2000 for stereo), not to much more expensive equipment (which would include the Mac 2105 priced in today's dollars).

    FWIW, in a follow-up review for the Pro version, Gary Gallo mentioned that the raw rail voltage was upped to 32 VDC vs. 30.

  10. #110
    Music Junkie E-Stat's Avatar
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    Quote Originally Posted by Feanor
    I also understand that there is the opinion that "excessive" capacitance is worthless anyway.
    My direct experience suggests otherwise. I find that *conventional* engineering practice is woefully inadequate. I owned an Audire amp back in the 70s in the heyday of Frank Van Alstine's "Double Dyna 400". I rigged a similarly configured supplemental power supply to the Audire by upping the capacitance to 120,000 uF (and a new 30a bridge!). Dynamic swings were handled with a greater impact and ease driving Magnepan MG-IIs. Every amp I've heard that I would consider to possess that elusive sense of "authority" has considerable power supply stiffness.

    Quote Originally Posted by Feanor
    FWIW, in a follow-up review for the Pro version, Gary Gallo mentioned that the raw rail voltage was upped to 32 VDC vs. 30.
    It is the regulated value that the output devices actually see.

    rw

  11. #111
    Vinyl Fundamentalist Forums Moderator poppachubby's Avatar
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    Quote Originally Posted by E-Stat
    Sorry for not responding. EICO is a venerable brand which produced some fine gear. I would consider them in the same favorable light as Dynaco who also offered kits. I think the preamp I owned some time ago was a HF-85. It had nice sound and I ended up giving it to a girlfriend. Back in my teens, I had fun building two Dyna kits. Great bang for the buck!

    Speaking of power supplies, the first thing that Frank Van Alstine did with any Dyna product was to substantially beef up the power supply. I had the FET-5 upgrade to a PAT-5 back in the 70s.

    rw
    Thanks for the input E. I will be modding the cramped RCA inputs. Also, EICO has laid out the inputs in a non conventional manner, in terms of current day pre amps. I will switch them around. It has the original Mullards and overall is dead quiet, so I won't mess with too much more. The previous owner recapped it.

    The real question is whether or not the RIAA circuit can be made to sound sweet. I have a Creek OBH 18 into the line stage, which is dead quiet and detailed.

    I have decided my upgrade path...an ARC SP9 into dual mono Golden Tube SE 40. I have a while to go still...

  12. #112
    Music Junkie E-Stat's Avatar
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    Quote Originally Posted by poppachubby
    It has the original Mullards and overall is dead quiet, so I won't mess with too much more. The previous owner recapped it.
    Good plan.

    Quote Originally Posted by poppachubby
    I have decided my upgrade path...an ARC SP9 into dual mono Golden Tube SE 40. I have a while to go still...
    I'm very pleased with my SP-9 for use with vinyl. As a hybrid, it has lots of gain and is very quiet. I use a mid output MC cartridge. I would, however, recommend getting at least a MKII. I began with that and had it factory updated to the final MKIII version. The MKIII has slightly better resolution, more punch (again that doubling the capacitance thing) and has a more neutral lower midrange tonal response. The earlier versions were a touch thin there. The only nit I have to pick with the SP-9 is its crosstalk on the line stage which narrows the sound stage on CDs. Which is one of the reasons why I use passive attenuators instead of it with my CD source.

    rw

  13. #113
    Vinyl Fundamentalist Forums Moderator poppachubby's Avatar
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    Vinyl ( as you know) is the reason I want an SP9. ARC assume much about their market. I would rather have them leave out added circuitry, switches, etc in favour of adjusting the resistors myself.

    I had an older vintage amp, a rebadged Goldstar with gain adjustemenbt by the turn of a knob. 1.2 / 2.4 / 4.6. Very convenient but a look inside would indicate a price to be paid for it.

    I like the stripped down simplicity compared to the SP11, and of course the stripped down cost never hurt anyone either.

    What adjustments have you had to make to allow the MC to sound it's best?

  14. #114
    Music Junkie E-Stat's Avatar
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    Quote Originally Posted by poppachubby
    What adjustments have you had to make to allow the MC to sound it's best?
    None. My experience and that of a mentor finds that loading down MC cartridges is not beneficial. There are, however, loading "turrets" on the SP-9 designed for that purpose which require soldering. If you wish to experiment, I would suggest an approach I learned over at AA: solder the resistors to one leg of a Y adapter. That allows for quick changes.

    John Elison's adapter approach

    rw

  15. #115
    Vinyl Fundamentalist Forums Moderator poppachubby's Avatar
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    Wow, that looks great. I have read about shunt resistance for quick changes. This looks amazing. What's more incredible is that John Elison uses Monster products!

  16. #116
    Phila combat zone JoeE SP9's Avatar
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    High output MC carts work fine into the SP-9's 47K impedence. A low output MC would see the load the head amp or step up transformer has. Low output MC's like very low loads. My Marcof head amp has a 36 Ohm load.
    ARC SP9 MKIII, VPI HW19, Rega RB300
    Marcof PPA1, Shure, Sumiko, Ortofon carts, Yamaha DVD-S1800
    Behringer UCA222, Emotiva XDA-2, HiFimeDIY
    Accuphase T101, Teac V-7010, Nak ZX-7. LX-5, Behringer DSP1124P
    Front: Magnepan 1.7, DBX 223SX, 2 modified Dynaco MK3's, 2, 12" DIY TL subs (Pass El-Pipe-O) 2 bridged Crown XLS-402
    Rear/HT: Emotiva UMC200, Acoustat Model 1/SPW-1, Behringer CX2310, 2 Adcom GFA-545

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