Archive through April 17, 2005

Silver Member

Username: Simplymcintosh

Post Number: 243
Registered: Jan-05

Posted on Sunday, March 27, 2005 - 10:00 am:

Not surprisingly, I have no idea what absolute phase is. But, from what I'm reading, it is not just the system that can affect the phase. The recordings do too and there is not necessarily any commonality between the phase of the recordings. Which, it seems would require making adjustments based on the recording to truly maintain absolute phase. Do you do this Jan? Do you make adjustments frequently or do you have a setting based on the phase of the majority of the type of recordings you listen to?

http://www.gcaudio.com/resources/howtos/absolutephase.html

Now, off to do some research to see if I can figure out my subwoofer questions.

Relevant Product Info

Silver Member

Username: Simplymcintosh

Post Number: 244
Registered: Jan-05

Posted on Sunday, March 27, 2005 - 11:08 am:

I was wondering about something like this the other day. Lo and behold, it exists (even if it is, uh, ugly):

Tubes On The Go

Silver Member

Username: Simplymcintosh

Post Number: 245
Registered: Jan-05

Posted on Sunday, March 27, 2005 - 12:12 pm:

Since the SP3 has no subwoofer or preamp output, would a connection similar to this allow the use of a subwoofer? This looks like it would connect to the speaker taps of the amp and then speakers would run from the subwoofer?

http://store1.yimg.com/I/hsusubs_1831_396215

This particular sub is not one I'm interested in but found the pic and thought it might be a good indicator of the type of connection I would need. The sub I really want, the Rocket UFW-10, doesn't have this type of connection. It only has the LFE or XLR type.

jan, if the sub isn't in the corner, where should it be?

Silver Member

Username: Rick_b

New York
USA

Post Number: 979
Registered: Dec-03

Posted on Sunday, March 27, 2005 - 01:00 pm:

SM,

I can only speak for myself, but I never felt the need to run a sub with my 1.6's. Planar speakers, as you know, have very fast transient response, and tight bass. What they may lack is deep bass extention. I suggest you let your MMG's run in more, and your amp as well. I would let both get 200+ hours on them and re-evaluate at that time. What you think is lacking right now may change as you get use to planar sound. I found it very clean and articulate, just not a lot of impact or slam.

Cheers!

Gold Member

Username: Jan_b_vigne

Dallas, TX

Post Number: 3271
Registered: May-04

Posted on Sunday, March 27, 2005 - 02:19 pm:

"Panasonic B-flat Tube CQ-TX5500D is the world's first car receiver with a built-in vacuum tube"

With "a" tube? "Built in" makes it sound like the old Luxman integrated amps with the 12AX7 tube in the window at the front of the amplfier. The tube wasn't in the audio circuit, it had just enough voltage going through it to make it light up and was put in a place where the user could look at it.

First? Somebody should tell the copywriter that cars had tube radios before transistors were invented. Even those of us who grew up with 8 tracks know that.

****************

SM - Yes, the speaker level inputs on the HSU sub are what you'll need. In the case of the inoperative sub, it should be out of the room completely. For a functioning sub, corner placement can still lead to boominess. If you decide to go with a new sub, there are several methods used to determine the best placement of the sub. I tend to agree with Rick about listening for a while with the planars by themself. Consider getting the room acoustics and the equipment set up correctly before you add too much speaker for the space.

For a time, absolute phase was a hot issue in audio. Some manufacturers put phase switches on the front of the pre amp to allow easy changes in absolute phase. Those switches are now as uncommon as mono switches. Too bad about the demise of both. I know the Macs do not invert phase, most of the other equipment I own does not invert phase, but my tube pre amp does. I have my system set up for what sounds best over the widest number of recordings. This approach is similar to setting the VTA on your phono cartridge. You can find the most often correct position or you can obssess and change things constantly. If it were as easy as flipping a switch, I would check phase for each recording. As is, I go with what sounds right the majority of the time, realizing some recordings may be out of absolute phase. If you don't have a phase switch, you can set the system up with banana plugs or 1/4" phone plugs and switch as needed. That becomes a matter of which is more important to you; either absolute phase or the fewest breaks in the connections within your system.

The music you listen to will help determine the usefullness of absolute phase. If you listen to recordings that use simple recording techniques, phase can make a difference. The article you linked explained it well. Every piece of equipment a signal passes through, whether in the recording or playback chain, can reverse the phase (or worse, just shift the phase 45 degrees). If you listen to recordings that are highly processed, the issue of absolute phase is often meaningles to you.

Once a system is stabilized as far as components are concerned (and, in my case, the system has not changed drastically for quite some time), you can experiment with phase. It requires a short time listening and crawling around behind your equipment to get what can amount to the same change you might pay lots of money to obtain with new equipment. There are instances where I can't say a client didn't hear an improvement when they bought new equipment mainly because they got the absolute phase of their system corrected.

Gold Member

Username: Kegger

MICHIGAN

Post Number: 2340
Registered: Dec-03

Posted on Sunday, March 27, 2005 - 02:45 pm:

While Jan and Rick are in the wait and see camp for a sub, I think you know
where I'm at on the issue. And some of the best subs for the money are SVS
HSU and of course rel, some of the velodyne models can have great bang for the buck!

"Since the SP3 has no subwoofer or preamp output, would a connection similar to this allow the use of a subwoofer? This looks like it would connect to the speaker taps of the amp and then speakers would run from the subwoofer?"

As Jan said yes that one will work.

Gold Member

Username: Kegger

MICHIGAN

Post Number: 2341
Registered: Dec-03

Posted on Sunday, March 27, 2005 - 03:00 pm:

Sm that car radio you mentioned has been out for quite some time and if you see
it up close it's much nicer looking than the pic shows, check this out!

http://www.firingsquad.com/media/article_image.asp?fs_article_id=1137&pic_id=03

http://www.trygve.com/blog_2002_07.html

Silver Member

Username: Simplymcintosh

Post Number: 246
Registered: Jan-05

Posted on Sunday, March 27, 2005 - 03:52 pm:

Rick,

I agree, the bass is clean and articulate with the MMG, too. I'm not interested in slam, so to speak. I just wonder what I'm missing from the extension. In fact, I've been very happy with the overall balance of the MMG's and, in a month of listening, have not really missed having a subwoofer. Maybe I should stop wondering if I'm missing notes. :-)

Jan,

The absolute phase is something to add to the list. But, it sounds like something for the future once things have settled?

Gold Member

Username: Jan_b_vigne

Dallas, TX

Post Number: 3273
Registered: May-04

Posted on Sunday, March 27, 2005 - 08:33 pm:

"If it measures good and sounds bad, -- it is bad. If it sounds good and measures bad, -- you've measured the wrong thing." - Daniel von Recklinghausen (Chief Engineer H.H. Scott)

Silver Member

Username: Rick_b

New York
USA

Post Number: 981
Registered: Dec-03

Posted on Sunday, March 27, 2005 - 09:08 pm:

Great Quote.

John A.

Gold Member

Username: John_a

Post Number: 2919
Registered: Dec-03

Posted on Monday, March 28, 2005 - 08:03 am:

Yes, great quote!

"First? Somebody should tell the copywriter that cars had tube radios before transistors were invented."

Damn right. I remember waiting for my father's and brothers car radios to warm up.

Most HT-type active subs have a continuously-variable phase control, from 0� to 180�. I could not see much use for that in 5.1, but I think it would help in SM's planned set-up.

Silver Member

Username: Rick_b

New York
USA

Post Number: 982
Registered: Dec-03

Posted on Monday, March 28, 2005 - 11:35 am:

Kegger,

I just wanted to check in and let you know, that I am still blown away by the sound of the RCA's. I am vey curious to hear your impressions of your ASL SET amp. Have you had a chance to play with it yet?

Gold Member

Username: Kegger

MICHIGAN

Post Number: 2344
Registered: Dec-03

Posted on Monday, March 28, 2005 - 01:02 pm:

Rick I'm still experimenting but I love what I hear and this thing, it's much
more powerful than 8 watts has a right too!

I have a tough time describing sounds as I've mentioned before but the
words smooth and articulate come to mind. I would like to try another pair
of output tubes but 300B's aren't cheap!

I recently redid the xovers in my klipsch speakers to a much more minimal
design, a single coil in series with the 2 woofers paralelled (first order)
then a second order on the tweeter/horn. so the woofers only have a coil in their
path and tweeter/horn has a cap and padding resister in it's path.
Much less complex then the original and I'm still tweaking values but very close.
The sound is improved over stock!

I've tried several nos input tubes in the unit and it responds very well.
So far very very satisfied exspecialy for my entry fee! LoL!

I'm glad the tubes are doing you justice, I didn't want to work out a
transaction with you and not have the results we both thought you would get.

Silver Member

Username: Rick_b

New York
USA

Post Number: 983
Registered: Dec-03

Posted on Monday, March 28, 2005 - 02:38 pm:

Kegger,

I'm sure that SET sounds real sweet. With the Klipsch speakers, it should run in pure class A. Any more time spent with the EL84 based amps?

Two Cents

Silver Member

Username: Two_cents

Post Number: 530
Registered: Feb-04

Posted on Monday, March 28, 2005 - 02:49 pm:

Kegger,

Do you have a reference system or are you always running gear in and out of your system? What combination of equipment comes closest to your ideal sound? Do you find that it depends on the kind of music you're listening to?

Last question, are you pulling for the Spartans to spank the Tar Heels this week?

Gold Member

Username: Kegger

MICHIGAN

Post Number: 2345
Registered: Dec-03

Posted on Monday, March 28, 2005 - 03:53 pm:

2c that is a lot of questions that I don't have time to really answer correctly right now!

But I do have a reference system not in my main listening area. I use it to
compare equipment and double check myself as to what I think I'm hearing.

In my main system I swap out amps, preamps, speakers, tubes. (one at a time)
after they have been modded and tested in my reference system. I like extended
highs but not to far and can't stand sibulance so with hoirns tuned just right with
the combo of tubes and the efenciency can be incredably detailed. but I also like
a nice soulful midrange with powerful and extended bass so a 3-way design
is my usual speaker design of choice (but I like electrostatics and would love to own some)
I have a pair of monitors I built with a ribbon tweeter that sound awsome.

With the music I listen to and the speaker of choice I don't find any shortcommings
when everything is finally setup to my liking.

Lately I have been more critical of the upper registers and digital harshness.
That is part of the reason why I rebuilt the xovers in the klipsch (tame the horns).
And I run a zman tube enhancer out of my sacd/cd player and swao tubes. (digital harshness)

But when it's all said and done I do like tubes and horns!
Then I augment them with solid state and subs.

----------------------------------------------
Rick I have used the el84's a little more and find them rolled off but sweet. I like!
----------------------------------------------

Unfortunitaly I have the tar heels winning in my final against illinois! Go figure!
If the tar heels win so do I! So I have to root for the heels!

Gold Member

Username: Kegger

MICHIGAN

Post Number: 2350
Registered: Dec-03

Posted on Saturday, April 02, 2005 - 02:05 am:

No new tube info?

Ghia nothing from you?

Rick try anymore tube swapping?
Same with you 2C!

Silver Member

Username: Rick_b

New York
USA

Post Number: 988
Registered: Dec-03

Posted on Saturday, April 02, 2005 - 07:23 am:

Kegger,

Been busy at work, no time to play lately. I'll have to make some. Also getting the house ready to put on the market.

MC-2C,

Woild like to hear an update. Tube rolling is where the fun starts.

Cheers to all.

Two Cents

Silver Member

Username: Two_cents

Post Number: 543
Registered: Feb-04

Posted on Saturday, April 02, 2005 - 11:59 am:

Kegger and Rick,

Haven't had much time lately to tweak the system and I think I'm also suffering from upgrade fatigue. When I'm ready to try different tubes, I'm thinking of getting Mullard 12ax7s and/or EH EL34s. What do you think about that?

Rick, so you're really moving to the Sunshine State?

Silver Member

Username: Simplymcintosh

Post Number: 255
Registered: Jan-05

Posted on Saturday, April 02, 2005 - 12:14 pm:

Not much from me, either. I've been listening to a Reference Recording of Liszt this a.m. Sounds fine on the tube system. I did hook up a pair of "box" speakers to the Onix to see how it sounds. Let's just say the MMG's were quickly put back in place. lol.

No tube rolling for me, at this point. My guess is that is a couple of months away.

BTW, I removed the cages a week or so ago and found the cats haven't bothered it at all. Plus, with the cages off, the shelf above the amp doesn't get nearly as hot. Maybe without the cages, the heat has a wider dispersion point?

Silver Member

Username: Simplymcintosh

Post Number: 258
Registered: Jan-05

Posted on Saturday, April 02, 2005 - 01:09 pm:

Rick,

A guy on this thread is seeking some feedback about Ohm speakers. Do you still have yours? If you get some free time, maybe you can give him more feedback. :-)

Kegger,

I also told him about your system. He wants a 2 channel system but wants to keep open HT integration down the road.

Silver Member

Username: Rick_b

New York
USA

Post Number: 989
Registered: Dec-03

Posted on Saturday, April 02, 2005 - 01:23 pm:

2c,

Sounds like a plan to me. Yes, I am definitely moving to Florida, hopefully before August.

SM,

Thanks for the heads up. I'll see if I can be of any help.

Kegger,

Just keep on, keeping on my brother. LOL!

Gold Member

Username: Kegger

MICHIGAN

Post Number: 2351
Registered: Dec-03

Posted on Saturday, April 02, 2005 - 01:53 pm:

2C: "I'm thinking of getting Mullard 12ax7s and/or EH EL34s"

I would definatly do the 12ax7's as it's cheaper and a larger difference. IMO

But if your going to spend the cash to get mullards I would do telefunkens instead.

Now unless your system is a little bright and maybe needs filling out in the
lower regions then the mullards are what you want.
personaly I would go for some inexpensive rca's first.
Or if you want to splurge some ge 5 stars or rca clear tops. The older the better!

Gold Member

Username: Rick_b

New York
USA

Post Number: 1002
Registered: Dec-03

Posted on Monday, April 04, 2005 - 04:43 pm:

What is the role of the driver tube, and what is it's importance in the overall sound?

Gold Member

Username: Jan_b_vigne

Dallas, TX

Post Number: 3326
Registered: May-04

Posted on Monday, April 04, 2005 - 05:19 pm:

The driver stage(s) amounts to early gain stages where the signal is stepped up in voltage and impedance is shaped from the incoming pre amp signal. After the signal has been increased to a designated level it is then passed on to the output stages where the actual (large scale) amplification process takes place. Driver stages operate at low current and reasonably high impedance, like the pre amp, while the output stages are responsible for the current capability of the amp. (Such as it is in a tube amp. Most tube amplifiers do not have large current capability.) Until the signal is passed to the outputs, the impedance is kept relatively high whereas the output stages are then faced with having to drive a loudspeaker load of approximately 4-16 Ohms (or fed to a 25/70 volt transformer for distribution systems). To do this the output signal is fed to the output transformers which act as a step down/impedance matching device or the tubes are parallelled in a output transformerless design.

Since the drivers act as gain stages, they will have the same effect on sound quality as the pre amp tubes. In the Mac tube amps, the driver stage is comprised of three tubes per channel so the gain is lower in each stage which will lower distortion and noise. It also allows a lower impedance at the output of each stage to get more dynamic gain in the overall amplification stage. With three tubes per channel the effect of changing one tube is less significant than in an amp such as the ST-70 which uses one tube per channel.

Gold Member

Username: Rick_b

New York
USA

Post Number: 1004
Registered: Dec-03

Posted on Monday, April 04, 2005 - 05:48 pm:

Thanks Jan. So in the case of my JD-102B, I have one driver, and two pre-amp tubes. So the driver tube will have as much impact on the overall sound as the pre-amp tubes.

Gold Member

Username: Jan_b_vigne

Dallas, TX

Post Number: 3330
Registered: May-04

Posted on Monday, April 04, 2005 - 11:49 pm:

I can't predict the amount of change that one tube will have on the sound of the entire amp. It depends how the tube is used within the circuit. If more gain is developed in the pre amp (which is entirely possible since the designer could assume you would only use the pre amp mated with the associated power amp), the driver tube may play a minimal role in the scheme of the whole amp. In general I would say, yes, the driver will affect the sound in a noticeable fashion. If for no other reason than you are changing the sound before the large scale amplification of the output tubes. At the cost of small signal tubes, it is well worth the experiment.

Gold Member

Username: Kegger

Warren, MICHIGAN

Post Number: 2360
Registered: Dec-03

Posted on Tuesday, April 05, 2005 - 01:23 am:

Rick I keep forgetting your amp is an integrated which has the preamp section built in!

When you asked me if I had any tubes for sale I was thinking the tube that was
single must be a voltage devider tube or some design like that then the 2 tubes
were the driver tubes but after realizing my mistake I'm with Jan and I'm not
sure which of the small tubes would have the most signifacant change on the sound.

Like Jan said they may be very simular in the amount of change.
I'd be interested when you change all those tubes what your thoughts are!

Gold Member

Username: Rick_b

New York
USA

Post Number: 1009
Registered: Dec-03

Posted on Tuesday, April 05, 2005 - 10:23 am:

Can you explain recommended circuit type usage and circuit gain usage?

Such as:
low mic line level 100x gain
ultra low mic line level 1000x gain
moving magnet phono input 10,000x gain
moving coil phono input 100,000x gain

Which one is the right one for my amp?

Gold Member

Username: Jan_b_vigne

Dallas, TX

Post Number: 3335
Registered: May-04

Posted on Tuesday, April 05, 2005 - 01:00 pm:

"Which one is the right one for my amp?"

To do what? Are you trying to run a microphone into the amp?

I'm going to assume not and these are optional settings you can make for one input. Think of microphones and phono cartridges as the analogous portions of your system to your speakers. All three represent the "transducers" in the system in that all take one form of energy and convert it to another form of energy. Mics and phono cartridges take mechanical energy and convert it to electrical energy. Speakers do the reverse. In the case of the low level transducers gain must be applied early in the circuit for the pre amplifier to drive the rest of the circuit. (Pre amps and amps are best thought of as a series of gain stages.) The two types of mics they refer to would be; "low mic line level 100x gain", a dynamic mic with what is considered average output for a microphone. It requires minimal gain before being sent along on its path. An "ultra low mic line level* 1000x gain" would expect to see a condenser microphone which, like a moving coil, has very low output voltage and requires additional stepping up (gain) before leaving this stage of the pre amp. A dynamic mic can be viewed as the analog to a dynamic speaker, there is a voice coil that is excited by the movement of the membrane that is the mic's pick up. A condenser mic operates much like an electrostatic speaker with a membrane being energized by movement from the source and the movement is generating an electrical field by varying its relationship with a charged body. The condenser mic's pick up assembly, like the ESL, is smaller, thinner, lighter and more able to respond to the smallest details of the signal. There are also ribbon type microphones, but they still fall under the general classification of condenser mic.

"Condenser Microphone - A design of microphone capsule in which a capacitor (or condenser) is created by stretching a thin conductive diaphragm in front of a metal disc called a backplate. By positioning the two surfaces very close together, but not touching, a capacitor is created whose capacitance varies as the sound waves strike the diaphragm and change its physical relationship to the backplate. The electric charge required for this process to occur is provided by an external source, such as a power supply unit or phantom power delivered from the mixing desk. Condenser microphones have very few moving parts but are susceptible to shocks; however, their sensitivity and electrical characteristics far outweigh any detriments, and are the preferred choice of microphone when micing musical instruments or the human voice."

"Dynamic Microphone - A type of microphone capsule design in which an electrical audio signal is generated by a voice-coil or ribbon (called a diaphragm) moving within a permanent magnetic field. The diaphragm moves in response to actual sound pressure waves; moving within the magnetic field causes changes in magnetic induction, which comprise the audio signal. This type of transducer operates almost exactly like a standard loudspeaker, except in reverse.Dynamic microphones are often chosen in sound reinforcement applications due to their durability, expense (generally, they are the least expensive type of microphones), and ability to withstand very high sound pressure levels."

Of course, the two cartridge types are moving magnet and moving coil. Once again there is the same anology to speakers and microphones. The MM cartridge will move a somewhat massive magnet assembly within the field of fixed coils to produce a fairly high level signal, by comparison to a MC, that requires less gain. The MC will move the small, light coils against the field of the magnets and will produce a signal that requires more gain be applied before the signal can be sent forward.

I don't know if that tells you what you need to know, but those are the references made in what you gave me. The cartridges (and often the condenser microphone) not only require gain but also some signal shaping. In the case of the cartridge, the inverse RIAA curve must be applied. In these three cases there may also be a provision for loading (L/C/R) which is given.

*Since the condenser mic is much lower level than a dynamic mic, the appellation "line level" here is a bit misleading.

Gold Member

Username: Kegger

Warren, MICHIGAN

Post Number: 2365
Registered: Dec-03

Posted on Wednesday, April 06, 2005 - 05:30 pm:

Check these operating instructions out for a used piece of tube gear and the
first time you fire one up. Most sound straight forward and what others have
said including Jan but one is a little strange but seems to make good sense!

-------------------------------------------------------------------------------- ------

First of all if you run across one of those great finds hope that no one plugged
it in to see if the tubes lit. Chances are they did, but maybe for not very long.
The first thing to do with an old piece of gear is to check the tubes. That might
be the reason it was taken out of service to begin with. The second thing is to
make sure you get all working tubes back in their original places so before you
do, the first thing is mark the tubes so you know where they were placed.
Usually a bit of cleaning is in order and a large soft bristled paint brush is a great
dusting tool to start with. Get rid of much dust as you can.

Bake the piece. I know it sounds strange but remove the bottom cover, check for
strange deposits of wax or capacitor oil and if none is present then pop it in to the
oven upside down. If you can set it at 175 that will be good. The upside down is
to allow any moisture inside the transformers to escape. Do it right side up and
steam can get trapped and later short out your transformer. The reason for this
is that carbon resisters will slowly get moisture ridden and go out of tolerance.
This is to get them back in so a couple of hours will take care of that. Needless
to say, carefully look power cords and replace if need be. Check the fuse, you do
want it to be original ,ie, correct value. Now you are ready for the variac!

Gold Member

Username: Jan_b_vigne

Dallas, TX

Post Number: 3368
Registered: May-04

Posted on Wednesday, April 06, 2005 - 07:18 pm:

I assume you are referring to the baking process that I never mentioned. It's an old trick that is the equivalent to pouring oatmeal in your crankcase to get an old engine to seal its gaskets. It's dangerous and, at best, is only a temporary fix. The idea is to reheat and redistribute the potting solution that is surrounding the windings in the transformer and various components. I didn't mention this because it is equivalent to me suggesting the way to light your house is to build bonfires in each room. It is up to you whether you want to try this method of "restoration". Let me know if it works and for how long. I've honestly never had the guts to try this. The better way to go, in my opinion, is to bring the unit up slowly on a Variac and let the potting materials do their own thing. Either they will resettle or not. The best solution is to just replace the parts that are defective.

Gold Member

Username: Kegger

Warren, MICHIGAN

Post Number: 2366
Registered: Dec-03

Posted on Thursday, April 07, 2005 - 02:53 pm:

hey Jan I'll be looking for a tube fm stereo tuner at this fest.

any suggestions not toooo expensive?

how is the dynaco model 3?

Gold Member

Username: Jan_b_vigne

Dallas, TX

Post Number: 3379
Registered: May-04

Posted on Thursday, April 07, 2005 - 03:07 pm:

The Dyna tuners were OK. If you can find a lower priced Scott tuner they were, as far as I remember, considered the superior product to the Dynas. The Pilot's and Eico's were not too bad for what you'd probably pay for them. I haven't thought much about tuners for years. I'll rumage around through some of my older stuff and see what suggestions I can find.

Gold Member

Username: Kegger

Warren, MICHIGAN

Post Number: 2367
Registered: Dec-03

Posted on Thursday, April 07, 2005 - 03:38 pm:

sounds good thanks!

anything you might want me to look for for you?

Gold Member

Username: Jan_b_vigne

Dallas, TX

Post Number: 3384
Registered: May-04

Posted on Thursday, April 07, 2005 - 06:06 pm:

Thanks, no. Like I said, my money has all gone to the back room lately. All my tubes are working, so nothing I need right now.

Gold Member

Username: Jan_b_vigne

Dallas, TX

Post Number: 3405
Registered: May-04

Posted on Saturday, April 09, 2005 - 03:28 pm:

Kegger - I spoke to a friend who has a restoration service locally and asked about tube tuners. His suggestion would be look for a Fisher tuner. Very stable and good sounding. Next would be the Mac's and the Dyna's. He would stay away from the Scott unless you can realign them on a regular basis which will require special equipment. He is less inclined to sugest an HK or Sherwood. Everything else that is likely to be reasonably priced is lower quality in his opinion.

Gold Member

Username: Kegger

Warren, MICHIGAN

Post Number: 2368
Registered: Dec-03

Posted on Sunday, April 10, 2005 - 02:03 am:

One of the guy's on audiokarma.org offered to sell me a pretty good dyna for $85
plus shipping I may do it. Any idea if that's a decent price?

Man just got home from karmafest whoo I'm beat, but I go back tommorrow! WEEEE!!

I'll try to get pictures, there was some killer sh!t there.

SEE Yu!

Gold Member

Username: Jan_b_vigne

Dallas, TX

Post Number: 3415
Registered: May-04

Posted on Sunday, April 10, 2005 - 03:11 am:

TOOOOOOOOOOOOOOOBES - GOOOOOOOOOOOOOOOOOOOD!!!

The MC240's are up and going again after being out of the system for almost a year waiting for the back room to get finished. They got a new set of Svetlana 6L6's (supposedly the last of the "great" Svetlanas before things changed hands and lines merged - great line to close the sale.) Right out of the boxes with the transformers stone cold the sound is terrific. I'm totally unclear on what exactly is the situation with the Russian tubes right now. I am certain though these Svetlanas are miles ahead of the Sovtek 5881's I had in the amps last time out. "Great sound at a bargain price" they were not. The change to the Svetlanas is worth every penny.

The story on getting the 240's up and running again is worth telling (probably).

The back room is 95% ready to go, so it was time to start sorting out the hifi for back there. The new tubes got taken out of their containers and the amps got put up on the table for a quick cleaning. The caps in the amps are twenty years old now so any time an amp sits there is a danger of the caps drying out and then there can be problems when the amp gets hit with AC voltage. I should have run these up on a Variac, BUT NO, not me. Let's plug them into 120 volts and see just what happens. So what if I take out a few output tubes along the way. Yeah, right!

Cleaned and with new tubes the amps got put in the spare bedroom to listen for problems before they move into their new home. The first amp went in to place and the speakers were connected. The Macs have a thermistor and a choke in the soft start up circuit so they take a few seconds to light the tubes. I plugged the amp into the Panamax and turned out the room lights to see how things would come up to operating temperature. About ten seconds after the amps are plugged in the first glow of filament voltage starts to light the tubes in almost a year.

The tubes stabilize with no gas burn off and no sparks inside the tubes. I place my ear to the speaker ... dead quiet! Not a sound can be heard. Is this good or is this bad? The CD goes into the player and the volume on the pre amp is raised very slowly. Music! Familiar Mac tube music. So the quiet is a good sign. I turn the volume down and start to clean the second amp.

Repeating the procedure for the second amp the new tubes go in and it gets hooked up to a speaker before I plug it into the Panamax. With voltage going in, I turn out the lights to see what is happening with the tubes. After about fifteen seconds the tubes start to light and there is a spark in one of the Ei 12BH7's. Blue light shimmering up and down the inside of the tube bottle. Crackling starts to come from the 3/5a. Not a good sign, I don't want to blow up a speaker, they're hard and expensive to replace now days. I turn on the room lights and bend down to check the tube to see if this is just some gas burning off (hopefully) or a leaky tube or signs of problems elsewhere in the amp. Just as I get eye level with the amps sitting on the floor the tube gives a bright spark and

blam

By the time I pick myself up off the floor several feet away from where I was a moment ago, the smoke and smell are already filling the room. The explosion was about the same as an M80 going off next to my ear. Anything that blows up with 450 volts going through it is impressive!!! Quickly I unplug the amps and think about the possibilities. It is now after midnight so there's not much to be done until the morning. I shut everything down and go to bed wondering how much this is going to cost. I have no idea whether the bang took out the tubes or not. Dollar signs snuggle up with me for the night.

This morning I pull the amp into the kitchen and put it on the table. The bottom cover comes off and I find one of the small bypass caps I had placed across the large filter caps has met its maker (Mallory). The inside of the amp looks like a pinata factory has exploded inside of it. All the connectors and switches have capacitor bits all over them. Relieved to find it is not a consequential piece of componentry and probably just a bad capacitor, I clean the amp up and snip out the blown up part. A new fuse that doesn't look like it met the French Resistance goes in, and I hope it was just a bad bypass cap and nothing more.

Tonight I plug everything in again and the same 12BH7 starts to spark. Lots of crackling through the speaker no matter what I do. I shut the amp down again and swap the bad plug with the good plug in the other side of the monoblock. With AC in, the same BH7 is still crackling and shimmering. It will not burn off the gas. Suddenly ... the crackling stops.

Terrific I think, the tube has cleaned itself up. Nope, the tube is still going to town but now there's no sound at all from the speaker. The woofer still moves so this is probably not too bad. It's back to the rear closet to dig out some spare tubes. A quick exchange for some old Groove Tube BH7's and let's try this again.

This time everything works perfectly. If you listen, you can hear the Macs playing in the background right now. Give a listen ...

Pretty good, huh? Just listen to that sound ...

Yeah, I know but you can't have them.

Gold Member

Username: Jan_b_vigne

Dallas, TX

Post Number: 3416
Registered: May-04

Posted on Sunday, April 10, 2005 - 03:14 am:

Kegger - That's fair price if you are sure it is in good working order and doesn't need alignment.

John A.

Gold Member

Username: John_a

London
U.K.

Post Number: 2987
Registered: Dec-03

Posted on Sunday, April 10, 2005 - 04:38 am:

Amazing post, Jan. Ecoustics should pay you for stuff like that.