Valve amplification (tubes)

madmax

Well guys,
After thinking about it for over 7 years I finally took a leap and made my best deal for a tube amplifier. In about a week and a half I should have it. It is a Jolida 302 and uses the EL-34 tubes. It is 50 watts per channel class AB which means it is compromised somewhat from a class A in order to up the output wattage. Class AB is a push-pull configuration. I should have a lot of fun trying each of the SDA's with this new family member. Is 50 watts per channel going to do anything??? I read the reviews and they tell me yes. Should be a good learning experience one way or the other. Anyone else had experience using tube amps with SDA's? Oh no, I forgot to make sure they were common ground! I guess I'll find out.
Thanks,
madmax

RuSsMaN

The Cary tube pre was a real nice touch on the SDA2b demo I got a couple days ago. (even though the tubes were near the end of their life, and spitting a little bit) You will notice more 'hiss' at idle than a good solid state, but I don't see how you could be unhappy with a true 50wpc.

I'll be interested in hearing your thoughts after you receive it....

Cheers,
Russ

PS, once I get my solid state scene under control, I'll be setting up tube monoblocks....

jrausch

Make sure your common ground is confirmed before you test your amp output. Or else your speakers will let out a pissed off growl if you don't. I just had a bad experience with it.


Peace:cool:

soupbone

Sorry Madmax I have some bad news for you. Tube amps and sda don't mix. Not because of the comman ground issue but because of the output impedance on most tube amps is very high. The sda speaker effect will only work with an amplifier that has a low output impedance. Almost all solid sate amps have very little or no output impedance. Almost all tube amps have a high output impedance. The power 1 from sonic frontiers is one that will work, but it is one of the few. What to look for in a tube amp is a high damping factor. With a high damping factor the output impedance is usually low. I received this information from Matt himself. I'll try to dig up the email from Matt to get you more details later. Soupbone

madmax

Oh no! If you can find the email I would appreciate it. If this amp can not drive SDA's properly I will be very disapointed. I was just sitting here trying to figure out whether to use the CRS's or the 2.3 TL's or the 1C's as the main listening speakers. If non of those work I may end up with an amp I don't want.

By the way this would explain a few things:
1: In general different amps I have excite the SDA effect differently.
2: My latest amp, the sunfire 300, has a standard output and a "tube-like" output. The standard output had better SDA effect than the "tube-like output did.
3: So far some of the best amps for the SDA effect that I own is the carver PT1250's and one of their claims to fame is a damping factor of over 200!

I think I may be screwed here.
Thanks for the heads up anyways. Lets hope this particular amp will be reasonable. If not, check out the Flea market forum.
Thanks,
madmax :<(

madmax

Ok,
I feeling a little queasy here. Has anyone else had experience using tube amps with SDA's?
madmax

madmax

Russman,
Didn't your listening session of SDA's use a class A tube amp? I'm just wondering because in your original review you talk about a 25 wpc tube amp but above you only talk about a Cary tube pre-amp.
Thanks,
madmax

RuSsMaN

Cary TUBE Pre
Bedini 25wpc solid state class A

Sorry if I wasn't clear....

I still beg to differ, I'd like to hear a straight tube setup for myself....

Cheers,
Russ

madmax

So the Bedini was a solid state. No problem, I thought it was a tube amp. Just read it wrong. Thanks for clearing that up. I'll let you know if a tube amp causes any problem. I wonder if there are any mods I can make to the SDA's if this is a problem? Tomorrow I plan on buying some resistors to put in line with the speakers to determine if a high output resistance really makes a difference. So long as we all learn something I don't really mind making a mistake on amp selection. I wonder what a good set of speakers would be given that the SDA's wont work well?
madmax

soupbone

Madmax, You took the words right out of my mouth. The carver sunfire is a perfect example. The sunfire has a choice of two outputs. A current source and a voltage source. One of the outputs has a high output impedance. (I think it is the voltage source) It is designed to sound like a tube amp. Bob Carver thinks the high output impedance on tube amps is what gives them that wonderful sound. So on that output he installs a resistor that raises the impedance. I thought about buying a sunfire amp and bi-wiring it with the voltage source on the tweeters and the current source in the woofers. I own a pair of 1.2Tls and am biamping with two aragon 2004 amps. I purchased a cary audio aes 25 super amp signature edition. But with its zero feedback and high output impedance it just wouldn't give any sda effect. I hope your jolida works for you! Soupbone

DarqueKnight

Madmax,

Bob Carver, isn't he the guy that said he could duplicate the sound of any amp just by duplicating its transfer function? Remember the sales hype for the Carver M 1.0t that said it copied the sound of Conrad-Johnson Premier 5 monoblocks ($6000/pair )? Oh, Carver never mentioned the Premier 5's by name in any of his ads, but he described his "reference amplifier" explicitly enough so that there was no doubt as to which amp he purportedly was copying. Don't you remember all that controversy?

See, now you can have the best of both worlds: Just run on over to Ebay and pick up a M 1.0t amp (200 watts per channel). It's a nice amp. I used to own one up until the early part of 2001. I sold my 15 year old M1.0t on Ebay for 70% of what I paid for it new. You might even catch my old unit back in circulation. It was a sweet sounding amp. It wasn't prone to the hum problems that plagued some M 1.0t's. Mine was serial #2298. :cool:

madmax

I like the Carvers. I have a set of silver 9t monoblocks but lately I have been using them to drive subwoofers. I really like the older Soundcraftsmen amps. (In particular the 7502). I started using them because the sound is very smooth. Nicer than the Carvers for my setup.
I am trying the Jolida because I hear it is a good example of what a tube amp should be but is still entry level class as far as price goes. It will be fun to find what differences there are even if the SDA dosen't work properly. (if thats the case). I can see it sitting in a small listening room, darkened, with the tubes glowing and some very sweet music coming out. I don't think for a minute it can compare with the gut wrenching power peaks of the solid state stuff I have but it might be a pleasant listening experience!
madmax