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The Dean Markley CD Series Club

Discussion in 'Amp Owners Clubs' started by Mr Perch, Feb 9, 2013.

  1. Mr Perch

    Mr Perch Tele-Afflicted

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    Hi -- I may be the only member. I just bought a CD30, 30 watt two-channel all-tube amp. DM also makes a 60 and a 120 watt version, lord knows why, because the 30 watt version has enough power to level a city block. It has a 12" Celestion "Rocket 50" speaker, channel switching, and multiple stages of overdrive. It's essentially a boutique tube amp that an ordinary guy like me can afford, unlike the Dumbles or Two Rocks. I hope that other owners of Dean Markley tube combo amps will show up here so that I may commune with them.
     
  2. bdgregory

    bdgregory Tele-Afflicted

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    not a Dean Markley - but a predecessor - JMF Spectra 30T
     

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  3. Mr Perch

    Mr Perch Tele-Afflicted

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    Welcome to the club! I'm aware of the Spectra amps. Are you gigging with it?

    Here's my similar rig:

    [​IMG]
     
  4. Mr Perch

    Mr Perch Tele-Afflicted

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    Someone PMed me a question, and in answer, there was the original CD series in the 1980s, and the re-issue series now. I have a re-issue CD 30. The difference is digital reverb instead of spring reverb, some fancier tone controls, and (IMO) a marginally cooler look to the control panel.

    I have seen a number of 1980s-vintage CD 60s available used from Guitar Center. My esteemed colleague Gnobuddy, the eminence grise of the Super Champ XD club, has looked at a schematic for one of the CD series amps, and in his view, Dean Markley is understating the actual power rating for the amps. I know that my CD 30 seems substantially louder than the 60 watt Tech 21 amp I had been using.
     
  5. Gnobuddy

    Gnobuddy Friend of Leo's

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    The only thing I'm eminent at is sleeping-in improbably late on weekends.

    The schematic I've seen does not include DC voltages or enough information about the transformers to make an estimate of the amps actual power. The reasons I believe the amps output power is underrated are circumstantial and historical: firstly the original 1980's CD-30 was subsequently re-branded and sold as the CD-40 (rated at 40 watts), and secondly a pair of 6L6GC tubes typically generate about 55 watts according to Wikipedia. In the Dean Markley CD-60, a single pair of 6L6GC tubes generate 60 watts.

    Traditionally Fender amps use the smallest and cheapest possible components (tubes, transformers) and push them beyond the manufacturers stated maximum limits in the attempt to squeeze out a little more power at the lowest possible cost. Remember, Leonidas was an accountant before he began manufacturing amps or guitars. Cost-cutting was deep in his bones.

    It would appear that the Dean Markley CD-30 amp designer took the opposite approach, using hugely powerful tubes (which in turn require hugely capable transformers) and using them in an amp rated conservatively, and well below their capabilities. Here we have tubes capable of 60 watts being asked to deliver only 30 or 40 watts instead.

    I'll bet this was partly done so most of the same components could be used in the CD-60 and CD-30/CD-40. While I don't have the schematics and other information to prove it, it would seem likely that the CD-30/CD-40 was actually a CD-60 running at a slightly lower voltage to turn down its power just a tiny bit.

    Perhaps Dean Markley also wanted to offer more value than Fenders bean-counting approach to amp design. During the earliest days of the Industrial Revolution, steam-engine inventor and manufacturer James Watt did the same thing; a one-horsepower Watt steam engine actually did more work than one typical farm horse could do.

    Watt deliberately understated his engines ability (and oversized the unit he came up with, the horsepower), hoping to impress farmers who found that, say, a five-horsepower Watt engine could actually do the work of six or seven horses. He figured this would keep his customers happy and encourage them to tell their friends what a good deal one of his engines was.

    The same tactic might still work: after all you seem pretty impressed by how loud this "30 watt" amp is, compared to other brands of "30 W" amps out there.

    While I'm not an engineer, I think rather like one, and I'm much more impressed by the hardware inside the box than the advertising in the magazines. It appears to me, Mr. Perch, as though you may have found a genuine pearl by stepping a little off the beaten path in your amp choice.

    Congratulations!

    -Gnobuddy
     
    Last edited: Feb 10, 2013
  6. Mr Perch

    Mr Perch Tele-Afflicted

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    On the other hand, with all that juice, it seems unlikely that I'll ever drive the power amp section enough to get much power tube overdrive. I'm glad I didn't get the CD 60.
     
  7. Gnobuddy

    Gnobuddy Friend of Leo's

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    There is always the speaker attenuator option. It seems ridiculous and inefficient to generate too much (very expensive!) audio power and then throw away some of it as heat just to keep volume levels manageable, but it does work. I've been doing that at home with the SCXD for a long time now, to get good tone and low volume at the same time.

    The other thing I forgot to mention earlier is that, while there is no industry standard for measuring guitar amp output power, usually the stated power is what you get with the amp still clean. You get substantially more power when the output tubes are overdriven.

    In a mathematically perfect world of perfect power supplies and no losses, you'd actually get double the power or 100% more at full overdrive. More realistically, you'd probably a 50% increase with good transformers and power supply components.

    So the CD-30 actually puts out at least 40 watts clean, and very likely one and a half times that - 60 watts - when overdriven hard. :eek: No wonder it was levelling buildings and slaying small animals with sheer sonic impact!

    It's time to get some musicians earplugs to protect your hearing: http://www.earplugstore.com/nasopl.html

    -Gnobuddy
     
  8. Mr Perch

    Mr Perch Tele-Afflicted

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    Actually, there's a upside to all that power, and that is if I want a clean tone, I can get it, even when competing with drums. I'm actually quite satisfied with the overdrive tone I get with the master volume at 3. The main challenge is finding the right combinations of gain and the various tone boost switches to get the optimum tones for different styles. For blues I like a moderately overdriven bridge pickup with midrange boost, or a neck pickup with treble boost, or the middle selection with extra dirt. You can see that it's getting complicated already, and we haven't even gotten to the clean jazz tones or the fusion stuff.
     
  9. Gnobuddy

    Gnobuddy Friend of Leo's

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    I'm quite interested in this amp, as it seems so much more versatile than the PRRI I'm using now, and so much better value for money too. The trouble is all that giant-killer power is way, way, way too much for my needs and usage.

    So, hoping against hope, I have to ask: in your opinion, is it possible to get decent clean and slightly overdriven tones at apartment-friendly volume out of this amp?

    I know you and I have very different ideas of what constitues "quiet", so let me add that I mean a volume comparable to an unamplified acoustic guitar; a volume that an un-amplified singer can compete with.

    The video clips I've seen suggest that maybe this amp does nice cleans even at these very low volumes, so the big question is whether you can get anything other than a perfectly clean tone out of it at these low volumes.

    -Gnobuddy
     
  10. Mr Perch

    Mr Perch Tele-Afflicted

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    It's one of these situations where you have to balance the master volume precariously right at the point where it threatens to cut off the sound. Or alternatively, you can set the amp for more gain than you actually want, and then turn down the guitar volume -- that seems to work. Plus, you have your patented attenuater device, right?

    I rehearsed with a jazz group today, and the jazz tone from the amp is very good. It's not necessarily easy to to get a big, clean, warm tone from a Tele, but it went well with this amp.
     
  11. Gnobuddy

    Gnobuddy Friend of Leo's

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    I had a chance to meet a Dean Markley CD-30 in the flesh, err, in the Tolex. (I think it's the defective one you returned, Mr. Perch.)

    That is one heavy box for a single 12" combo. Unless they put a brick in the box, there are some really massive transformers in there. I think that confirms some hunches, including the reason for the really strong bass. Big beefy transformers handle low frequencies much better than the little weeny ones FMIC uses.

    It's also clearly way too much amp for my needs, so that puts that particular bit of incipient gear-lust back to sleep.

    It sounds as though this amp is full of good tones. To use an extremely ungrammatical colloquialism, you done good, Mr. Perch!

    -Gnobuddy
     
  12. Mr Perch

    Mr Perch Tele-Afflicted

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    Yes, you do have to be in shape to carry that thing up and down a flight of stairs. I'm hoping that is also an indication of durability.
     
  13. Mr Perch

    Mr Perch Tele-Afflicted

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    Gnobuddy, could you explain the principle behind the "effects send" and "effects return" controls on the back? I hooked up my little Univibe knock-off and I fiddled and fiddled trying to get the right sound at the right levels. I finally settled on "send" at 4 and "receive" at 8, but I have no idea why that works or what it means.
     
  14. Gnobuddy

    Gnobuddy Friend of Leo's

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    Basically the signal from the Dean Markley preamp either goes straight to the power amp, or (when you elect to use the FX loop) a fraction of it (controlled via the effects send potentiometer) gets routed out to the "FX send" jack.

    The signal then goes through your external effect, comes back into the "FX return" jack, is buffered, fed to the effects return control, and is then fed to the Dean Markley power amp.

    So the "FX send" knob controls how strong a signal is fed to the external effect. Setting this is simple: any time you deal with audio electronics, you get the lowest noise by using the strongest signal possible without distortion, a principle called "gain staging". So turn up the FX send knob until the effect misbehaves - distorts, etc - then back it off just far enough to stop the misbehaviour. (You'll want to do this while playing the guitar hard, so you have a good indication of the strongest signal level.)

    The "effects return" knob controls how much of the signal returning from the effect is fed to the power amp inside the Dean Markley amp. So you simply set this to get the volume you want; if you're going to be switching the FX loop in and out during a song, match the levels using this knob (effects return).

    If your external effect has its own output level control, that essentially does the same job as the CD-30's effects return knob. It doesn't exactly matter how you set each one, just fiddle with them so neither of them is all the way to one extreme of its range.

    -Gnobuddy
     
  15. Mr Perch

    Mr Perch Tele-Afflicted

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    I found that I had to set the return level on 8 to avoid a reduction of the overall amp volume, even when the effect is not engaged. What's up with that?
     
  16. Mr Perch

    Mr Perch Tele-Afflicted

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    Also, would there be any advantage to have the effect come before rather than after the pre-amp stage? My little vibe is True Bypass™, so I'm not worried about tone loss. I could just as easily run it from my guitar going into the amp.
     
  17. Gnobuddy

    Gnobuddy Friend of Leo's

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    That's very weird. There is nothing in the schematic to indicate that behaviour, and in fact the circuit was carefully designed to make sure the FX loop does not in any way affect the straight-through signal when the loop is bypassed.

    So I don't know why it's misbehaving - but I'm pretty sure it is misbehaviour, and not the way the circuit is supposed to work.
    Mainly the usual one: some effects sound better before distortion, some sound better after it. Since this amp can serve up significant distortion before the FX loop, the latter kind of effect will sound best in the FX loop.

    To me reverb definitely sounds better after distortion, so a reverb pedal would probably sound much better in the FX loop than in front of the amp. I'm not sure about the Univibe (phasing and tremolo), but my guess is they too would sound better after distortion rather than before.

    That's only a hunch though, I don't get along with the phasing effect and never use it, so I have no experience to pass along. I guess it comes down to you and your ears, then!

    -Gnobuddy
     
    Last edited: Feb 13, 2013
  18. Mr Perch

    Mr Perch Tele-Afflicted

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    It's strange, but the sound using the vibe through the effects loop seems inferior to that from putting it between the guitar and the amp. It seems to lose a lot of bass for some reason.

    I don't like conventional phase shifters, but I always coveted the Hendrix/Trower ethereal floating sound. I only plan to use it on three songs -- I mainly play blues, where it wouldn't be appropriate IMHO.
     
  19. Gnobuddy

    Gnobuddy Friend of Leo's

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    I can't see a reason (in the schematic) for that to happen, but I do know that guitarists constantly complain about FX loops causing "tone suckage". This looks like a well-designed FX loop to me, but in the end if your ears are not happy, they're not happy!
    Too much phasing and flanging on a song literally gives me a headache and sometimes makes me feel a little dizzy. The pitch never settles down, constantly warbling about, and for me the effect is like straining to read fuzzy moving letters - after a while I have a headache.

    The worst example I can think of is a DVD I have of three live performances by The Cure. The lead guitarist is relentless in continual and excessive use of pitch-shifting effects, and after a few minutes I get a headache and feel dizzy.

    My wife was surprised when I mentioned this to her, but then she sat down and watched a little of the DVD - and had the same thing happen to her. Headache, slight nausea, and dizziness.

    Not exactly the effect the muscians were hoping to have on their audience, I think!

    -Gnobuddy
     
  20. Mr Perch

    Mr Perch Tele-Afflicted

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    I can think of several alternative explanations for this phenomenon, including the excessive use of goth/transvestite facial make-up and the extreme monotony of their songs.
     
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