CAL Alpha and an Equalizer

Hi all, Hope you can please bear with me through this post to explain my findings, and a possible solution?

About 5-6 months ago, I bought a mint CAL Alpha DAC from another A-goner here, and have posted before, about its characteristics, and sound.

I don't believe there is anything specifically wrong with it per se, just typicaly Alpha sound.

Well, first thing I did notice when replacing my long owned CAL Sigma II DAC, was a very "lean" glassy, analytical, and very hot sound, like the DAC was hitting my Mac Pre-Amp a bit too much on the hot side.

I have bought a pair of Endler's 12 Step Attenuators, and that solved the hot output, but it still sounds a bit lean. Can an EQ be inserted between the DAC, and Pre-Amp? Mark
I think it would work, but it seems like you are doing too many "wrongs" to try to make a "right." Why not simply invest in a warmer sounding DAC or CD player and sell your current digital gear, since it is not to your liking???
What tubes and output cables are you using? I have an Alpha and those two things really affect the sound in my system.
Hi, Thanks for your responses.
When I recieved the Alpha, there were two JAN-Phillips 5751 tubes, and those I replaced with two Mullard CV-4004 (12AX7A Equivalent) Tubes.

I'm using top of the line Straightwire 75ohm Digital vetween the Transport, and DAC , and Straightwire Maestro 1M Cables between DAC and Pre-Amp.
Both Power Cords are stock CAL Cords.

I am using the Endler Attenuators at the lowest 4db cut, and the output seems smoother, not so hot, but I remember the Sigma II giving a little bit better Bass response versus the Alpha.

The rest of my system sounds fine with no complaints of bass response though my Analog set up, and R-R Tape Deck.

I would assume that yes, a EQ could be inserted just between the DAC, and Pre-Amp, but as other would most likely say, it's a band aid trying to fix something that shouldn't need fixing in this manner, and another CD Player (or DAC) would better solve the problem. Mark
The attens will Upset the input impedence, Get the Alpha.
I have an Alpha and certainly wouldn't describe it as "hot" or "lean". I'm using Sylvania 5751 tubes. Previously I had JJ 12AU7 I think and it sounded good with them (but not as good as the 5751's). A long time ago I had the Mullards and absolutely did not like them.

I agree with the previous posters in that you should be looking at your tubes, and if the problem still persists, try a different DAC or CD player rather than adding confounding variables.

Hiend2, You stated the attenuators will upset the input impedance? I assume you mean the input impedence going into my preamplifier, correct?

Cann anyone else comment about this? I'll ask too, Scott Endler about this.

Then you say Hiend, "Get the Alpha"? Get the Alpha what??? lol Mark
There should be no problem using attenuators between the DAC and the preamp. That is exactly what is done with CD players that have variable outputs, so that a preamp is not needed for volume control. You should notice that the preamp's volume control will need to be turned up a little more than before, but that's all.

The question I have is whether you really need them. Have you measured the voltage of the DAC's output when it is playing a known test signal like a 0dBFS or -20dBFS? The Redbook standard specifies 2.0 volts for a 0dBFS signal.

Regarding an EQ. Audiophiles tend to have a phobia about adding another component into the signal chain. A decent analog parameteric EQ, from say Rane, can do more good than harm if used properly. Typically, you want to apply EQ in the bass region below 250Hz because that's where the room has the most influence.
Hi Bob, Thank you for your response, and assurance that I didn' make a mistake about the Attenuators.

At the time, I hadn't thought of this, but I recall Cal Audio Labs used to ship the Alpha DAC from the factory with some resistors to alter-modify voltage output if needed, and these would be soldered in somewhere in the output within the unit.

As far as I can see, and understand, the Endler Attenuators gave me the same end result without the need of tearing into the unit, and soldering resistors, and also the advantage of variable output to whatever I desire with these 12 step Attenuators Robert Endler makes which I believe go from 4db to 48db cut.

I knew right away with this Alpha that the Alpha was much higher output versus my year's ago vought new Sigma II, as I can barely get my Mac MX-130's to 11, and it's blowing you our of the house, and makes you put your hands over your ears with such a shrill, len sound. Truthfully, I feel my Sigma II to be a better sounding unit, and this shouldn't be considering the higher original price of the Alpha.

I had perhaps considering buying, and inserting something like the Berhinger DEQ2496 between the DAC and Pre-Amp, and also as another option perhaps even trying the DEQ2496 elsewhere in the chain between Pre Amp-Amp?

Of course I have Bass+Treble Tone controls on the MX-130, and could perhaps just turn up the bass higher, and turn down the treble below flat a bit? Mark
FWIW, I have both the Alpha (original, not the 24/96 version) and Sigma II and driven by the Delta there is not a huge difference in sound. I think the Alpha is more detailed and may have a tad more extension in the bass and highs but its subtle and on causual listening its hard to distinguish them. What does seem to make a difference though is using a different transport with the Alpha (than the Delta) and not running them thru seperate filters on a power conditioner. Especially the latter. I'm not sure it's relevant but my Delta has a high output much like the Alpha, both of which are well over the nominal 2v of my other CDP's.
Mark, if you were accustomed to setting the preamp's volume control at a certain position based on your previous source, then the level difference is more than likely what you are perceiving as "leaness." The only sure way of comparing the Alpha to the Sigma is to match their levels with a voltmeter and then listen.

Analog EQ devices are usually inserted before the amplifier or in a tape loop of the preamp so it can be switched in and out of the chain.

The DEQ2496 as you know is a digital device and will do an analog to digital conversion if given an analog input. If it will accept a digital input, that would probably be preferable.
perhaps the problem is the transport. i too have a cal alpha and am not thrilled with it. iwas surprised, because the seller described the dac as warm. i changed the tubes several times.

it is possible that the "right" line cord can help.

beware of opinions oregarding warm dacs and cd players. there are very few of them around. i have listened to quite a few. most of them are any thing but warm.

you will have to spend big bucks to get a warm dac. maybe an older sonic frontier will do.
Hi again all,
No, I think the transport is fine, has always worked just fine. Sure, I'll agree, and won't debate there's probably 100's of transports out there that will easily best the CAL Delta I have.

Running a search through the archives on the CAL Alpha, and various Tubes, I did come across a post from Zinfan (Tom) who remarked that the Mullard CV-4004 Tube in his own CAL Alpha DAC was "un-involving", or something similar to this effect, and I believe I'm noticing perhaps the same thing, as these may be the exact same Tubes Tom was referring to. He, in fact "gave me free!" a set of the Mullard CV-4004 to try, and I'm betting that these are the exact same pair he tried, and didn't personally care for.

As others have mentioned in older threads about the Alpha, these particular Units seemed to be a bit more sensitive to Tube Rolling, and as Tom has found, the Sylvania 5751 3-Mica Black Plates were the very best choice he found.

I don't doubt him on this, but truthfully, it can start getting awful expensive with experimentation with Tubes, even these small signal Tubes, and I sure wish I could find a relatively inexpensive alternative to try, without blowing a virtual week's pay for a pair of tubes! :-)

I was honestly thinking of trying again, the el cheapo Sovtek 12AX7AWPS just for the heck of it, but in truth, I read some mixed comments about these, both good, and some not so good.

At least with the JAN-Phillips 5751's that were in it before, dynamics, involvement, and Bass seemed a bit better at the expense of highs that seemed to be a bit too glassy, and "screechy". Mark
I believe the Alpha's output voltage by default is 4V, and is adjustable by replacing resistors. Sometimes there are benefits to having a high-output CD player, as I found out using a low-powered integrated.

If you want to try different tubes on the cheap, I would recommend the JJ's. They're very inexpensive. The downside is that JJ's are known for a more "lean and detailed" presentation; this seems to be what you're trying to avoid. Maybe EH instead? I tried Sovtek's and wasn't thrilled with them. But nothing compares to the Sylvania 5751's in my experience thus far.

Good luck. I think the Alpha is a great DAC for the used prices we're seeing now, and it's been in my system for over 5 years now; nothing else in my rig has had that kind of staying power.

I've used both old and new Tesla's /JJ's, EI's, EH's and Sovtek. EI's had a very smooth top end neutal/warm mids, but not strong bass. The JJ's were as Michael described and not very sturdy. The EH's have a full bass and were fairly neutral thru the mids and highs. I was expecting them to be bright and etched. They were not! The Sovteks were cold and enimic. Bottom line I'm using EH's in both units.
Hi Newbie, You mentioned brand, but not number of Tube?
I assume by "EH", you are referring to Electro-Harmonix, correct?

Is it the 12AX7 EH you refer to?
Of course too, there are a number of different model Sovtek in 12AX7 (3 I believe?) Was it the Sovtek 12AX7LPS you tried?

I've seen some new NOS Sylvania Gold Brand 5751WA 3 Mica BlackPlates w/Square Getter on the net somewhere, but asking price is $140ea, and I'm thinking that this is a bit out of line, regardless how nice they are! Thanks, Mark

Electro-Harmonic 12AX7EH. The Sovteks were the 12AX7LPS (a lot of folks seem to like these, I find them bright and I had three early failures as well) and the 12AX7w?? which were junk and I threw them out. Regarding the high priced NOS, Ive used very little of it. I've just got too much tube stuff to maintain and if I started using them in all my stuff I'd go broke. On those few occasions I do they find their way into tube phono and line stages where they can make a much bigger impact. One good thing about the Cal units though, they aren't hard on tubes - you get a lot of life out of them.
Hi all again,
I've come to this realization about the Cal Alpha (through the archives) and perhaps other equipment like this, that shares similar qualities.

Tube rolling is the key to suitable sound, but one sad fact, is that if one wants to put in a pair of NOS Sylvania 3-Mica BlackPlates with D-getter, be prepared to pull your pants down.

I just bought four c-9 version Shuguang-Sino 12AX7 tubes to try. In all honesty, they might be better than the crap shoot buying "supposed" NOS tubes from the online scalpers. Mark
Mark I have to agree with you regarding the tubes. I have had better luck using current production tubes than NOS stock in my Alpha as well. I do prefer NOS 12AU7’s and 12AT7’s to current production types in my other gear. A few years back I had an Alpha, which I bought here and it came with Golden Dragon’s. The printing on the tubes was very detailed, unlike some others I have seen lately. They may have in it for years before I got it, who knows? Those were the best of all the 12AX7’s I had ever tried in it. The guy I sold it to, was so nice I sent them along with a few other NOS brands. I am now regretting it. I’ve had my present Alpha for a month and I am really missing them. I have an order in for some 1990 NOS Golden Dragon’s and I’ll let you know how they sound.
Hi again all,
I'd like to conclude this post, and end it with some very nice news, that all is well in CAL Alpha-Land!

As was later suspected, and through the help of all you kind helpful folks here, and especially Tom (Zinfan) the CAL Alpha has been known to be a bit more sensitive to Tube Choices than it's less expensive sister, the Sigma-Sigma II DAC.

Yesterday, I recieved 4 new 12AX7A-c9 Shuguang Tubes from an Ebay seller (for $24.00 plus shipping) and after installing them this afternoon, and doing a test listen, my CAL Alpha has never sounded so durn good!!!!

I won't doubt other's findings about Vintage NOS Tubes Like Sylvania 3-Mica BlackPlates, etc being grand, but I honestly cannot see substantial gains being made, as this Unit of mine seems to lack absolutely nothing at the moment. I'm sure after a bit of breakin, they'll even sound a bit better!

I am surprised at the nice build quality of these Chinese Tubes, posessing 3-Mica Spacers, and BlackPlates to boot (Appear to be a round-halo getter)

I hope this post to this thread helps other CAL Alpha owners to find a nice Tube, in which one won't have to run the gamut of NOS Vintage Tubes, and spend a veritable week's paycheck to get enjoyment. I've found these Tubes to offer quiet operation, solid authorative Bass, smooth, crystal clear mids, and superb, soild highs, without being Tizzy, or harsh, andgreat dynamics.

I'm very glad that A-Gon is here for us all, and wish to thank all again who've responded to me here, and in the past. Mark D.
hi markd51:

i have a cal alpha and have tried a variety of tubes and have found the dac insensitive to tube changes.

just for the record, have you found any tube which rolls off the treble and shifts the balance to the lower mid range ?

the chinese tubes you mention, i assume are current production easy to find.

i am surprised you like the tubes. i have yet to hear anyone speak well of chinese 12ax7 tubes.
Mr T, There are a number of folks on the AA tube forum that have posted positive comments about these tubes. Haven't heard them myself, and I don't know what about them differentiates them from the croud. Nor have I heard anyone describe them as rugged, but the good new is they are cheap.
Hello MrTennis, and Newbie,
To speak of my own personal findings with my own (Bought new in 1997) Sigma II, and my bought used from A-Gon Alpha DAC, I have noticed quite substantial changes in the sound, and here's my own personal experiences with both Units:

With my Sigma II, when I first got it, I had noted the stock Chinese Tube in it, it sounded very darn good, and then thought I was going to make sonic improvements to the sound, changing out the one 12AX7A, and trying out the then touted Sovteks. In this Unit, every Sovtek I tried, which was every model available 6 years ago including the 12AX7LPS sounded dull, lackluster, and the detail, clarity, and slam that the Sigma II DAC once had was gone slightly. I threw the stock el cheapo Chinese Tube back in, and in fact that tube still sits in that DAC 7 years later with no problems.

Now onto the Alpha I acquired: When I got it, it came with two Phillips-Jan 5751 Tubes, and the sound was extremely brittle, screechy, bright, and essentially unlistenable in this Alpha in my particular system.

A very kind A-Goner by the name of "Zinfan" (Tom) seen my earlier cries for help some months back, came to my aid, and rushed me out both a Copy of the Alpha Owner's Manual, and a pair of virtually New-NOS Mullard CV4004 Tubes to try in the DAC, as he noted a bit of rolled off highs with this particular Tube in his Alpha.

Well, I noted the same, and again, thought of this particular Tube as being lakcluster, and seemed to restrain the Alpha of its true capabilities.

I was right, when I had just gotten these Shuguang, 12AX7, and these are the latest C9 version, which have BlackPlates, Triple Mica Spacers, and a round Halo Getter. Very nicely made Tube IMO, and I'm of the thinking that this Tubes is an improvement over older Shuguang 12AX7's. Just like the three bears, this tube seemed to be "Just Right" (for me anyway, and my particular McIntosh-JBL Based System, 2-2105's MX-130, four L-65's)

I cannot speak for the Shuguang 12AX7Ac9 version longevity, but generally it's been found pretty much that both the Alpha, and Sigma II DAC's are very "easy" on Tubes. In other applications perhaps, this may not be the case for the Shuguang, so I cannot honestly say either way.

It is pretty much a well knows fact the the '50's Sylvania 5751 BlackPlate Triple Mica with D-Getter to be one of the top vintage "12AX7 type" Tubes in these Units as far as sonics are concerned, but I've also heard that this particular Tube has a relatively short life. Perhaps installed in either the Alpha, or Sigma II, this wouldn't be an issue. Biggest problem is, thier rarity, and thier very high desireability, and cost. I seen a pair of these NOS Sylvanias being sold online last week by a dealer for $140 ea!

IMO, this is just too much no matter how nice they are.
Of the two Mullard CV4004 I have which I had noted rolled off the highs-mids a bit, I really cannot sell these, as they were in essence truthfully "borrowed" to me by Tom, and if I didn't care for them, I was to send them back to him. I in fact just wrote him a letter yesterday asking if he would like them back, as they are rightfully his. Mark D.