The Dynaco Tube Audio Forum

Dedicated to the restoration and preservation of all original Dynaco tube audio equipment - Customer support for Dynaco VTA tube amp kits, all Tubes4hifi.com products and all Dynakitparts.com products


    Just bought an SP14 and PH14

    Share

    Dave_in_Va

    Posts : 129
    Join date : 2013-04-02

    Just bought an SP14 and PH14

    Post by Dave_in_Va on Sun Mar 20, 2016 11:53 pm

    I've got a used SP 14 coming in this week. I don't know too much about it but I know it has EH 6SN7's in it. I'm super excited as I'm also getting the PH14 with it.
    I'm sure the EH tubes are fine but I'm pretty sure some USA made tubes would probably sound better. I have a stash of old 6SN7's that test good on my Eico 666 but I'm not familiar with the concept of "matched quads" of preamp tubes. I get it for power tubes in guitar amps.
    Am I okay using some of my stash in the SP14 without any "matching"? I have GE, Raytheon, Sylvania, Zenith, etc. Of course, I don't have any way to tell if these tubes might be microphonic.
    Or should I buy a "matched quad" of NOS 6SN7's from a dealer? I've noticed the prices on these vary WIDELY.
    Thanks for the advice. I'm sure I'll have other questions after the gear arrives as I've never used a stand alone phono pre-amp.

    peterh

    Posts : 642
    Join date : 2012-12-25
    Location : gothenburg, sweden

    Re: Just bought an SP14 and PH14

    Post by peterh on Mon Mar 21, 2016 2:00 am

    Dave_in_Va wrote:I've got a used SP 14 coming in this week. I don't know too much about it but I know it has EH 6SN7's in it. I'm super excited as I'm also getting the PH14 with it.
    I'm sure the EH tubes are fine but I'm pretty sure some USA made tubes would probably sound better. I have a stash of old 6SN7's that test good on my Eico 666 but I'm not familiar with the concept of "matched quads" of preamp tubes. I get it for power tubes in guitar amps.
    Am I okay using some of my stash in the SP14 without any "matching"? I have GE, Raytheon, Sylvania, Zenith, etc. Of course, I don't have any way to tell if these tubes might be microphonic.
    Or should I buy a "matched quad" of NOS 6SN7's from a dealer? I've noticed the prices on these vary WIDELY.
    Thanks for the advice. I'm sure I'll have other questions after the gear arrives as I've never used a stand alone phono pre-amp.
    There is usually no need to "match" tubes in a preamp.

    Dave_in_Va

    Posts : 129
    Join date : 2013-04-02

    Re: Just bought an SP14 and PH14

    Post by Dave_in_Va on Mon Mar 21, 2016 2:04 am

    Thanks Peter. That's what I thought.

    deepee99

    Posts : 1260
    Join date : 2012-05-23
    Location : Wallace, Idaho

    Re: Just bought an SP14 and PH14

    Post by deepee99 on Mon Mar 21, 2016 11:01 am

    peterh wrote:
    Dave_in_Va wrote:I've got a used SP 14 coming in this week. I don't know too much about it but I know it has EH 6SN7's in it. I'm super excited as I'm also getting the PH14 with it.
    I'm sure the EH tubes are fine but I'm pretty sure some USA made tubes would probably sound better. I have a stash of old 6SN7's that test good on my Eico 666 but I'm not familiar with the concept of "matched quads" of preamp tubes. I get it for power tubes in guitar amps.
    Am I okay using some of my stash in the SP14 without any "matching"? I have GE, Raytheon, Sylvania, Zenith, etc. Of course, I don't have any way to tell if these tubes might be microphonic.
    Or should I buy a "matched quad" of NOS 6SN7's from a dealer? I've noticed the prices on these vary WIDELY.
    Thanks for the advice. I'm sure I'll have other questions after the gear arrives as I've never used a stand alone phono pre-amp.
    There is usually no need to "match" tubes in a preamp.

    Matching is a confusing term. Yes, no need to match one tube with another in a pre-amp tube, unlike the big outputs, but the triodes should be matched internally in preamp tubes. Most reputable sellers will do this for you.
    About the only way you're going to find out if your tubes are microphonic is to plug them in and when they're good and warm, give the chassis (or the selector switch) a good thump. You'll hear kind of a "boing" through the speaks. This doesn't mean they're bad tubes; some of my best are quite sensitive in that way but unless it affects the sound that's just a fact of life.
    Start with the Sylvanias and work your way down. Most of the Syls (VT-231s) I have are quite microphonic if you tap the chassis anywhere near them, but that has no impact on how they sound. As a friend recently said, "How often are you going to go tap-dancing on the top of your pre-amp?" It's a non-issue in the SP-14, but might be of greater concern in the phono section, however I would yield to higher intelligences on that topic.

    peterh

    Posts : 642
    Join date : 2012-12-25
    Location : gothenburg, sweden

    Re: Just bought an SP14 and PH14

    Post by peterh on Mon Mar 21, 2016 11:14 am

    deepee99 wrote:
    peterh wrote:
    Dave_in_Va wrote:I've got a used SP 14 coming in this week. I don't know too much about it but I know it has EH 6SN7's in it. I'm super excited as I'm also getting the PH14 with it.
    I'm sure the EH tubes are fine but I'm pretty sure some USA made tubes would probably sound better. I have a stash of old 6SN7's that test good on my Eico 666 but I'm not familiar with the concept of "matched quads" of preamp tubes. I get it for power tubes in guitar amps.
    Am I okay using some of my stash in the SP14 without any "matching"? I have GE, Raytheon, Sylvania, Zenith, etc. Of course, I don't have any way to tell if these tubes might be microphonic.
    Or should I buy a "matched quad" of NOS 6SN7's from a dealer? I've noticed the prices on these vary WIDELY.
    Thanks for the advice. I'm sure I'll have other questions after the gear arrives as I've never used a stand alone phono pre-amp.
    There is usually no need to "match" tubes in a preamp.

    Matching is a confusing term. Yes, no need to match one tube with another in a pre-amp tube, unlike the big outputs, but the triodes should be matched internally in preamp tubes. Most reputable sellers will do this for you.
    About the only way you're going to find out if your tubes are microphonic is to plug them in and when they're good and warm, give the chassis (or the selector switch) a good thump. You'll hear kind of a "boing" through the speaks. This doesn't mean they're bad tubes; some of my best are quite sensitive in that way but unless it affects the sound that's just a fact of life.
    Start with the Sylvanias and work your way down. Most of the Syls (VT-231s) I have are quite microphonic if you tap the chassis anywhere near them, but that has no impact on how they sound. As a friend recently said, "How often are you going to go tap-dancing on the top of your pre-amp?" It's a non-issue in the SP-14, but might be of greater concern in the phono section, however I would yield to higher intelligences on that topic.

    What's the definition of "match" then ? Is it equal between triodes ? or is it equal
    between a pair of tubes ? Or is it with the spec for said tube ?

    deepee99

    Posts : 1260
    Join date : 2012-05-23
    Location : Wallace, Idaho

    Re: Just bought an SP14 and PH14

    Post by deepee99 on Mon Mar 21, 2016 11:32 am

    peterh wrote:
    deepee99 wrote:
    peterh wrote:
    Dave_in_Va wrote:I've got a used SP 14 coming in this week. I don't know too much about it but I know it has EH 6SN7's in it. I'm super excited as I'm also getting the PH14 with it.
    I'm sure the EH tubes are fine but I'm pretty sure some USA made tubes would probably sound better. I have a stash of old 6SN7's that test good on my Eico 666 but I'm not familiar with the concept of "matched quads" of preamp tubes. I get it for power tubes in guitar amps.
    Am I okay using some of my stash in the SP14 without any "matching"? I have GE, Raytheon, Sylvania, Zenith, etc. Of course, I don't have any way to tell if these tubes might be microphonic.
    Or should I buy a "matched quad" of NOS 6SN7's from a dealer? I've noticed the prices on these vary WIDELY.
    Thanks for the advice. I'm sure I'll have other questions after the gear arrives as I've never used a stand alone phono pre-amp.
    There is usually no need to "match" tubes in a preamp.

    Matching is a confusing term. Yes, no need to match one tube with another in a pre-amp tube, unlike the big outputs, but the triodes should be matched internally in preamp tubes. Most reputable sellers will do this for you.
    About the only way you're going to find out if your tubes are microphonic is to plug them in and when they're good and warm, give the chassis (or the selector switch) a good thump. You'll hear kind of a "boing" through the speaks. This doesn't mean they're bad tubes; some of my best are quite sensitive in that way but unless it affects the sound that's just a fact of life.
    Start with the Sylvanias and work your way down. Most of the Syls (VT-231s) I have are quite microphonic if you tap the chassis anywhere near them, but that has no impact on how they sound. As a friend recently said, "How often are you going to go tap-dancing on the top of your pre-amp?" It's a non-issue in the SP-14, but might be of greater concern in the phono section, however I would yield to higher intelligences on that topic.

    What's the definition of "match" then ?  Is it equal between triodes ? or is it equal
    between a pair of tubes ?  Or is it with the spec for said tube ?
    Peterh, et. al, a typical preamp tube (6SN7, 6CG7, or most any of the 12xx7s as well as the 6922 and variants), are actually two tubes (triodes) enclosed in one bottle. Both triodes inside that single tube should have equally matched performance levels. This is easily checked on a Hickock. So the matching is WITHIN the tube, not amongst different tubes. On output or power tubes, the matching is between separate tubes, so you're getting an equal push-pull effort -- a whole different critter. But on pre-amp tubes you want internal matching; the test results apply to a single tube. As long as the results add up in each tube, it doesn't matter how you scramble the eggs. Tung-Sols to the left, jokers to the right, doesn't matter.

    Tube Nube

    Posts : 603
    Join date : 2008-12-06
    Age : 53
    Location : Calgary, AB

    Re: Just bought an SP14 and PH14

    Post by Tube Nube on Mon Mar 21, 2016 1:59 pm

    As to microphonics . . . Heheh. Apparently that's pretty common with 6sn7s. Traditionally, you'd give the tube a flick while the amp is on. With mine, i just have to tap the case of the pre amp, and I can hear the thump through the speakers.

    I dont hear any trouble when playing music, and not thumping on my preamp.

    Soon I'll be in the market for some of the more highly recommended tubes, like the Sylvanias.

    Dave_in_Va

    Posts : 129
    Join date : 2013-04-02

    Re: Just bought an SP14 and PH14

    Post by Dave_in_Va on Mon Mar 21, 2016 2:45 pm

    After getting some info from Roy, it looks like I'm receiving a PH15 and an SP14. I've already placed an order for some extra 6X5 and 12X4 rectifiers as I didn't have any of those in my tube stash (mostly guitar amp tubes).
    So I'm now looking at a couple of 6922's and four 6SN7's. I guess I'll keep my 6SN7's for spares and start with a NOS set.
    One dealer has some Sylvanias from the '40's for $50 a pop. I guess that sounds reasonable as I'm used to seeing NOS prices for 12AX7's 6L6GC's and EL34's.
    Do any of you have a preference for 7308's over 6922's?
    Or should I just go with the obvious common sense approach and see how the EH sound?

    Kentley

    Posts : 300
    Join date : 2015-03-06
    Age : 64
    Location : Worcester, MA

    Re: Just bought an SP14 and PH14

    Post by Kentley on Mon Mar 21, 2016 3:11 pm

    Please be aware that, in the SP-14, the pair on the left side of the board (from the front) are the volt amps, and as such are far more critical for SQ than the pair to the right (buffers). No need to seek out four NOS 6SN7s. Pretty much any decent functional pair will suffice as buffers, whereas the volt amps may be the most critical place in your entire signal path for sound quality. As for the EH brand, I personally found them both dull and so microphonic that it affected SQ. Good luck - there's a LOT of 6SN7 types out there and they all sound different.
    Methinks you will love your new toys!

    Dave_in_Va

    Posts : 129
    Join date : 2013-04-02

    Re: Just bought an SP14 and PH14

    Post by Dave_in_Va on Mon Mar 21, 2016 3:30 pm

    Thanks Kently.
    That's great info. So I'll just look for a nice pair instead of a quad.

    tubes4hifi
    Admin

    Posts : 1261
    Join date : 2008-11-30

    Re: Just bought an SP14 and PH14

    Post by tubes4hifi on Mon Mar 21, 2016 3:47 pm

    Dave got a real steal of a deal, if I'd seen them I would have bought them myself, at half the price of a new kit!
    Dave - for the phono tubes, many of the 6DJ8 & 7308 types can be highly microphonic, so I'd suggest you only buy tubes that have been pre-tested
    for low noise, very important in the phono stage. The final 12AU7 in the PH15 isn't critical, as it's just an output buffer, no gain.
    For new tubes, check out all the various options here . . . http://www.upscaleaudio.com/vacuum-tubes/preamp-tubes/6922-6dj8-7308-pcc88/
    the Philips and Pope 7DJ8s are excellent. Also Jim McShane can pre-test Genelex Gold Lion tubes for you.
    For used tubes, check here . . . http://tctubes.com/6DJ8-6922-ECC88-E88CC-7308-tubes.aspx
    and also here . . . . http://www.audiotubes.com/6dj8.htm

    deepee99

    Posts : 1260
    Join date : 2012-05-23
    Location : Wallace, Idaho

    Re: Just bought an SP14 and PH14

    Post by deepee99 on Mon Mar 21, 2016 3:48 pm

    Tube Nube wrote:As to microphonics . . . Heheh. Apparently that's pretty common with 6sn7s. Traditionally, you'd give the tube a flick while the amp is on. With mine, i just have to tap the case of the pre amp, and I can hear the thump through the speakers.

    I dont hear any trouble when playing music, and not thumping on my preamp.

    Soon I'll be in the market for some of the more highly recommended tubes, like the Sylvanias.
    Dave, never directly tap a hot tube. Go banging around it all you like, but don't whack 'em directly. It establishes a bad karma between you two, because it is sitting there helplessly in its socket.

    deepee99

    Posts : 1260
    Join date : 2012-05-23
    Location : Wallace, Idaho

    Re: Just bought an SP14 and PH14

    Post by deepee99 on Mon Mar 21, 2016 4:18 pm

    tubes4hifi wrote:Dave got a real steal of a deal, if I'd seen them I would have bought them myself, at half the price of a new kit!
    Dave - for the phono tubes, many of the 6DJ8 & 7308 types can be highly microphonic, so I'd suggest you only buy tubes that have been pre-tested
    for low noise, very important in the phono stage.  The final 12AU7 in the PH15 isn't critical, as it's just an output buffer, no gain.
    For new tubes, check out all the various options here . . . http://www.upscaleaudio.com/vacuum-tubes/preamp-tubes/6922-6dj8-7308-pcc88/
    the Philips and Pope 7DJ8s are excellent.   Also Jim McShane can pre-test Genelex Gold Lion tubes for you.
    For used tubes, check here . . . http://tctubes.com/6DJ8-6922-ECC88-E88CC-7308-tubes.aspx
    and also here . . . . http://www.audiotubes.com/6dj8.htm

    Don't neglect the 7DJ8s for sure, which are dirt cheap and prolly the best buy in the 6922 arena. The (7) denotes a one-volt higher filament voltage than the the (6)DJ8s, which is not harmful to the power supply. I run them in my phono preamp and no worries. Filament or heater voltages swing within about 10 percent of quoted rating, anyway. The 7-volt rating scares some people, which is what makes them such a good deal. Your iron doesn't give a darn at such low currents.

    Dave_in_Va

    Posts : 129
    Join date : 2013-04-02

    Re: Just bought an SP14 and PH14

    Post by Dave_in_Va on Wed Mar 23, 2016 9:10 am

    My pre-amps are arriving today.
    I'm not too clear about the separate gain controls on the SP14. Why is there a separate gain control for each channel?
    Do you usually run the gain controls at 100% and then adjust with the master volume? Or the master vol. at 100% and then adjust the vol. with the separate gain controls?
    Thanks.

    Kentley

    Posts : 300
    Join date : 2015-03-06
    Age : 64
    Location : Worcester, MA

    Re: Just bought an SP14 and PH14

    Post by Kentley on Wed Mar 23, 2016 9:14 am

    Dave_in_Va wrote:My pre-amps are arriving today.
    I'm not too clear about the separate gain controls on the SP14. Why is there a separate gain control for each channel?
    Do you usually run the gain controls at 100% and then adjust with the master volume? Or the master vol. at 100% and then adjust the vol. with the separate gain controls?
    Thanks.
    The separate gain controls are useful in lieu of a "balance" control. Most of the time, it's recommended to keep both L+R gains at max, and use the master volume for, well, volume.

    Dave_in_Va

    Posts : 129
    Join date : 2013-04-02

    Re: Just bought an SP14 and PH14

    Post by Dave_in_Va on Wed Mar 23, 2016 9:25 am

    Was it set up this way because of the separate power supplies?
    Seems like a balance control would be simpler and do the job.

    deepee99

    Posts : 1260
    Join date : 2012-05-23
    Location : Wallace, Idaho

    Re: Just bought an SP14 and PH14

    Post by deepee99 on Wed Mar 23, 2016 10:31 am

    I like the separate L+R pots; eliminates any cross-talk between the channels. The L+R pots, at full clockwise, are shorted out of the circuit on an SP-14. However, I don't hear any audible distortion using them just so I can get some use out of the volume control.

    Kentley

    Posts : 300
    Join date : 2015-03-06
    Age : 64
    Location : Worcester, MA

    Re: Just bought an SP14 and PH14

    Post by Kentley on Wed Mar 23, 2016 10:39 am

    I believe the separate stepped attenuators are more durable and accurate than a balance control, and as deepee says they are effectively removed from the circuit when at "max", which can't be said of any balance control design of which I am aware.

    tubes4hifi
    Admin

    Posts : 1261
    Join date : 2008-11-30

    Re: Just bought an SP14 and PH14

    Post by tubes4hifi on Wed Mar 23, 2016 1:53 pm

    two stepped attenuators are much higher quality and much more accurate than a cheap balance control.
    Set 'em once for your system setup (gain and balance) and you're done with them. Use the master volume control.

    deepee99

    Posts : 1260
    Join date : 2012-05-23
    Location : Wallace, Idaho

    Re: Just bought an SP14 and PH14

    Post by deepee99 on Wed Mar 23, 2016 2:29 pm

    tubes4hifi wrote:two stepped attenuators are much higher quality and much more accurate than a cheap balance control.
    Set 'em once for your system setup (gain and balance) and you're done with them.   Use the master volume control.
    Yep, what Roy said. Khozmo pots (http://www.khozmo.com/), which are two-stepped, are the finest I've ever encountered.

    Dave_in_Va

    Posts : 129
    Join date : 2013-04-02

    Re: Just bought an SP14 and PH14

    Post by Dave_in_Va on Wed Mar 23, 2016 2:47 pm

    Set 'em once for your system setup (gain and balance)

    So I should turn them all the way up and just use the master volume? I've never had any use for a balance control anyway except once in a blue moon to check to see if both channels are working properly. My listening chair is in between my two speakers (like most people, I guess).

    (These just arrived and I won't be able to set them up until Fri. or Sat.)

    Kentley

    Posts : 300
    Join date : 2015-03-06
    Age : 64
    Location : Worcester, MA

    Re: Just bought an SP14 and PH14

    Post by Kentley on Wed Mar 23, 2016 2:49 pm

    Dave_in_Va wrote:Set 'em once for your system setup (gain and balance)

    So I should turn them all the way up and just use the master volume? I've never had any use for a balance control anyway except once in a blue moon to check to see if both channels are working properly. My listening chair is in between my two speakers (like most people, I guess).

    (These just arrived and I won't be able to set them up until Fri. or Sat.)
    The majority of SP-14 users, it seems, find that maxxing the two gains is the optimal solution.
    Some have gone so far as to bypass them entirely or even to remove them from the front panel, leaving room for a remote sensor and an extra hole which may be utilized for....whatever.


    Last edited by Kentley on Wed Mar 23, 2016 3:04 pm; edited 1 time in total

    wgallupe

    Posts : 81
    Join date : 2014-05-18
    Age : 62
    Location : Central Mass.

    Re: Just bought an SP14 and PH14

    Post by wgallupe on Wed Mar 23, 2016 2:59 pm

    I have the left/right attenuators adjusted so that the Volume control works in a more usable 10 o'clock to 2 o'clock range.

    deepee99

    Posts : 1260
    Join date : 2012-05-23
    Location : Wallace, Idaho

    Re: Just bought an SP14 and PH14

    Post by deepee99 on Wed Mar 23, 2016 3:04 pm

    wgallupe wrote:I have the left/right attenuators adjusted so that the Volume control works in a more usable 10 o'clock to 2 o'clock range.  
    Moi aussi. I get little "gain" using the volume control if the L+R pots are maxed out. I have 'em set so that 12 o'clock on the volume control is about as high voltage as I need.

    Dave_in_Va

    Posts : 129
    Join date : 2013-04-02

    Re: Just bought an SP14 and PH14

    Post by Dave_in_Va on Wed Mar 23, 2016 4:15 pm

    I'm just going to dime the two gain controls. I only need one volume control.

    I really curious to see how these sound compared to the SP/PH10 I have (which sounds really, really nice).

    Sponsored content

    Re: Just bought an SP14 and PH14

    Post by Sponsored content Today at 1:01 pm


      Current date/time is Wed Sep 28, 2016 1:01 pm