[Mark Korda]

Hi Mpcrelly,Do you ever get in the mail those small green catalogs from Mapleshade? I get them every month. You can get them on line too. They have all sorts of quirky mods,wires,maple bases,and great sounding cd's. Pierre Sprey is the president. He worked on the concept team for the A-10 Tankbuster and F-16, and Grumman aircraft. His catalog is pretty cool. He does some mods on old Heathkit and Scott amps and tuners.I'm going to read you one of his quotes; A few years ago a freind who's a vintage tube specialist and I discovered the magic of 60's small tube amps(notably Scotts). These small EL-34 output tubes had startling low bass,unexpectedly clean and punchy,together with a soaring treble airiness. The bass and treble of the famous big tube amps(EL-34,KT-88's,6550's.ect) sounded soggy by comparison. I talked to him once when ordering some cd's,and I know he might have an answer for you. I also have an issue of Vacuum Tube Valley where the cover says...The EL-84,the Baby with Bite. I've never heard the other bigger tubes have had some thing like that said.Pierre's phone # for tech advise is (410)867-7543 or just Mapleshade in Google for the site..........take care.....Mark Korda

[mpcrelly]

well, still trying to burn in my amp....  irritation seems to be less, but still there....  keep hearing interesting details in the music that I don't think I've heard before, or at least heard as clearly....

[SteveFord]

New tubes will sound "off".
Your big amp is a much better piece than your little amp so I think you're hearing both more detail and more annoying new tube sound.

[Napalm]

Dunno guys I experienced something similar with some large ear-canal headphones....

 

[Vapor Audio]

Can't believe nobody has asked what speakers you're using.  Tonal imbalance with tube amps, first thing I'd think is a speaker with an impedance curve that doesn't mesh with the amp.  Tube amps are in general, much more sensitive to impedance swings than solid state. 

When comparing the amps, do you notice a tonal change between the two?

[Vapor Audio]

Dunno guys I experienced something similar with some large ear-canal headphones....

 

Love your avatar 

[Napalm]

Love your avatar 

Got me kicked from some another forum.... 

[mpcrelly]

ya nice avatar....my speakers are Dynaudio audience 72se.  a discontinued model.  the impedence is 4 ohms.  I didn't know the "impedance curve" is a method of matching amps to speakers?  where would I find that data?  what is the comparable data from the amp manufacturer be?

[medium jim]

Can't believe nobody has asked what speakers you're using.  Tonal imbalance with tube amps, first thing I'd think is a speaker with an impedance curve that doesn't mesh with the amp.  Tube amps are in general, much more sensitive to impedance swings than solid state. 

When comparing the amps, do you notice a tonal change between the two?

Tonal imbalance with tube amps...

That is a new one to me.  Then you indicate that tube amps are less adept at handling impedance swings?  Actually they are more adept as they are voltage regulated by nature, whereas SS isn't.

I think SteveFord was on point in that the bigger tube amp is more revealing, but is suffering the effects of low hour tubes, which will relax and bloom with more hours on them and any glare or otherwise will disappear, hopefully.

Jim

[Vapor Audio]

Tonal imbalance with tube amps...

That is a new one to me.  Then you indicate that tube amps are less adept at handling impedance swings?  Actually they are more adept as they are voltage regulated by nature, whereas SS isn't.

Tube amps are far more likely to have a less than flat frequency response into low impedances.  That's just the way it is.  Doesn't mean that's what happening in this case, but it's a possibility since he's using a 4 ohm speaker. 

[medium jim]

^ I'm driving a pair of Magnepan's, which are 4ohm and dip down to below 2 with tube amps without issues.  The beauty of tubes is that they can handle low impedances where SS amps tend to peter out unless they have a zillion watts and a worthy power supply.

Caveat, not all tube or SS amps are created equally and we are dealing with generalities.

Jim

[Napalm]

ya nice avatar....my speakers are Dynaudio audience 72se.  a discontinued model.  the impedence is 4 ohms.  I didn't know the "impedance curve" is a method of matching amps to speakers?  where would I find that data?  what is the comparable data from the amp manufacturer be?

There isn't any as there's more to it than just the output impedance of the amplifier:

http://en.wikipedia.org/wiki/Output_impedance

where you would be looking to keep the "damping factor" above some minimum (let's say 200-300 for starters).

Additional factors such as design limits on the max current / voltage that the amp could deliver,  thermal behaviour, etc. will practically make it impossible to evaluate based on the "output impedance" alone.

So your best bet is to take what they call in the article "rated output impedance" and compare with the speaker's impedance curve, make sure that the speaker has an impedance above the amplifier's "rated" one.

Some people say it's ok if the speaker has some impedance dips for a few frequencies ("it won't fry anything"), some others say it's not ("won't fry but it will distort on those frequencies"). Your call on this one.

[medium jim]

There isn't any as there's more to it than just the output impedance of the amplifier:

http://en.wikipedia.org/wiki/Output_impedance

where you would be looking to keep the "damping factor" above some minimum (let's say 200-300 for starters).

Additional factors such as design limits on the max current / voltage that the amp could deliver,  thermal behaviour, etc. will practically make it impossible to evaluate based on the "output impedance" alone.

So your best bet is to take what they call in the article "rated output impedance" and compare with the speaker's impedance curve, make sure that the speaker has an impedance above the amplifier's "rated" one.

Some people say it's ok if the speaker has some impedance dips for a few frequencies ("it won't fry anything"), some others say it's not ("won't fry but it will distort on those frequencies"). Your call on this one.

Not trying to be contrary, but my Marantz Model 9's only have a damping factor of 17 and I have no complaints, just aural bliss.  Personally, I think it all comes down to tubes and caps burning in, after all, we are talking about a new amp and it does take about 200 hours for Capacitors to fully form and about 100 to 200 hours for tubes to. The OP has already indicated that the fatigue has started to diminish or subside.  Give the big amp more hours and let's see.   

Jim

[Napalm]

I will agree that for tube and solid state amps you would be looking at different "minimal" damping factors, it also depends on the speakers, if they have a flat impedance curve you'll probably do well with *any* damping factor as long as the amp is not over-strained on some parameter (current / voltage  / thermal).

[mpcrelly]

OK TIME TO STOP THIS THREAD!!!


just let me        a few times....

Here is what I've concluded today, and some will think "how stupid can he be?".  INITIALLY I used the cronus hooked directly to the cd player.  then I started wondering if it would sound better with my bryston DAC in the B100?  so I hooked up the optical out (no coax out) from the cd player to b100 and used "rec out" to bypass preamp section of bryston.  with my limited knowledge of circuits I'm not sure if this really bypassed anything except the volume knob and balance.  after becoming frustrated with the cronus large movement volume remote control (too loud, too soft, then get out of chair and manually set), I decided to the volume controlled pre outs on the bryston so I could use the bryston volume remote and run the cronus wide open.  it sounded ok to me, but maybe the two preamp circuits were experiencing some extra distortion, harmonic? 

Maybe after all this, it was this double preamp setup was causing unpleasant, maybe very high frequency, distortion causing my ear discomfort.??

I guess I probably don't pay as close attention to sound changes as I hoped and was messing things up?

so after all this the seller allowed me to exchange the amp for the power amp only version of the cronus called the atlas.  I will update this thread of my findings.

sorry for the wild goose chase, but thanks for trying to help me out!

[Hank]

From Mark Korda's post: 

A few years ago a freind who's a vintage tube specialist and I discovered the magic of 60's small tube amps(notably Scotts). These small EL-34 output tubes had startling low bass,unexpectedly clean and punchy,together with a soaring treble airiness. The bass and treble of the famous big tube amps(EL-34,KT-88's,6550's.ect) sounded soggy by comparison.

I built a Scott LK-48B integrated tube amp kit in my teens and still have it in storage.  I remember it sounded better than any other amps I heard back in the day.  I've bought 3 more of that basic design factory built off eBay the past few years and have one almost recapped and with some resistor replacements - need to replace the selenium rectifier with a diode bridge and make following resistor changes to compensate for the higher bridge voltage output.  May have to wait for retirement to get all this done, but look forward to the Scott EL-34 sound.

[ltr317]

From Mark Korda's post:  I built a Scott LK-48B integrated tube amp kit in my teens and still have it in storage.  I remember it sounded better than any other amps I heard back in the day.  I've bought 3 more of that basic design factory built off eBay the past few years and have one almost recapped and with some resistor replacements - need to replace the selenium rectifier with a diode bridge and make following resistor changes to compensate for the higher bridge voltage output.  May have to wait for retirement to get all this done, but look forward to the Scott EL-34 sound.

That amp uses EL-84 output tubes, not EL-34.