Rerurn to Romy the Cat's Site

 A few things I would like to say in context of Pham’s playback.

I will leave his infatuation with turntables alone – man like to collect turntables and he within his constitutional right to do whatever makes him happy. The problem that I see is that in context of our objectives Pham’s tendency to museum TTs deluded the message. After all those pictures and accumulation of brand it is not know what he listen, what is his arms for what purpose. If the man lay out what TT, arm and needle he use for this or that satiation then it would indicate where he stay and what he is getting, or trying to get.  If it were some then it might be mutually educational.

Electronics, it is not clear what he uses but I see a bunch of low power tube amps at the shelf. Since he uses Accuphse DG-38 processor for crossovering then he is unquestionably multi-amping. The list names a bunch of DIY tube amp on 2A3, 211, parallel 2A3. 300B. I guess the do the job. I also guess that since Pham did not implement his second order crossover in his DIY tube amps but use Accuphse D-crossover then he use the Accuphse also for room correction purposes. I made this conclusion based upon the fact that Pham did not call his Accuphse as a crossover but he calls it as a “voicing equalizer”. I have no idea why he needs to equalizer the things he has so many channels ….

The Pham Acoustic System is the most interring thing on all of it of cause. Basically on the page presented two systems:

 Low bass: Under 71Hz – Driver Fostex FW800N 31.5 in. 
 Mid bass: 71Hz to 400Hz – Driver JBL 1500AL 
 Mid low: 400Hz to 1.600Hz – Driver Westrex T530A 
 Mid range: 1.600Hz to 5.000Hz – Driver Jim Lansing 375
 Mid high: 5.000Hz to 8.000Hz – Driver Jim Lansing 175 
 Treble: 8.000Hz to 12.000Hz – Driver Fostex T500Mk2 
 Tweeter: Upper 12.000Hz – Driver Mewon Ribbon TS01

And:

Low bass: Under 71Hz – Driver Fostex FW800N 31.5 in.
Mid bass: 71Hz to 500Hz – Driver JBL 1500AL with enclosure JBL 4344.
Mid low: 500Hz to 1.600Hz – Driver Ale 7550P with horn Goto S300.
Mid high: 1600Hz to 6300Hz – Driver Goto SG 370 with horn Goto S400.
Treble: 6300Hz to 10000Hz – Driver Fostex T500Mk2.
Tweeter: Upper 10000Hz – Driver Mewon Ribbon TS01.

It is obvious that one comes after another but the way the page organized it is not clear which system came first and which later. I am not going to make a guess but would like to look into both.

Both systems feature a single bass horn with Fostex 30” driver. My initial sentiment was that this is not horn but rather an infinite baffle as this horn has no depth. Then in the night picture on the site I recognized that it has some depth and the text describes it as 6 feet long. It is still very shallow horn but it is not clear what Pham is trying to do with it. This 30” Fostex has very light and very flexible cone that has a LOT of break up. When you punch the cone with your am at one location then you just do indentation under your hand but do not displace the whole diaphragm. This driver in my view need to be use very low and with very sharp filter, not allowing to it to do any HF. Pham use his Fostex 30” at 71Hz and 12db/oct. This is interesting. Since he stays at 71Hz not at 70Hz then I think this is an indication of deliberate precision. So, question is: can Fostex 30” in Pham case to cover midbass of Pham did it because not of his other channels can do midbass. I think the last one but truly to answer this question might be only the man himself.

The 71Hz to 400Hz region in both cases is covered by JBL 1500AL with JBL 4344 box. I love the older 1400ND JBL driver and I guess the 1500AL is a newer version. The JBL 4344 box is kind of funny little ported box. I presume Pham loves the sound of it. There is a picture of looks like 70Hz curved horn but there is no information about it.

Then Pham has his version of my Fundamental Chanel. In one case it handled by Westrex T530A driver and in another by Ale 7550P. In case the Westrex it looks like it loaded onto a much larger curved horn. The horn looks like 75-80Hz horn but he loads into it 400Hz driver with second order. What a waste of horn!!! On another side the use of Ale 7550P sounds more appropriate for Goto S300 horn.  I hate Goto horn but at least it is not as huge waste of the horn size.

Then we have MF devised in one case by :

Mid range: 1.600Hz to 5.000Hz – Driver Jim Lansing 375 
 Mid high: 5.000Hz to 8.000Hz – Driver Jim Lansing 175 
 Treble: 8.000Hz to 12.000Hz – Driver Fostex T500Mk2

And in another case by:

Mid high: 1600Hz to 6300Hz – Driver Goto SG 370 with horn Goto S400
Treble: 6300Hz to 10000Hz – Driver Fostex T500Mk2

Pham’s preference for using the Fostex T500Mk2 in upper range is obvious.  I do not know this driver. I used Fostex 90 and Fostex 900, not the T500Mk2. The switch from JBL 375/2440 to Goto SG-370 (or vice versa) is notable. I have no idea what JBL 175 does in there in such a narrow bandpass.   Interesting that using Goto he did not allow Goto to run over 6300Hz. It might be because he so much like his Fostex T500Mk2 or because he find that some inadequacy of Goto performance ay upper range. In any case the credits I think shall go to the Fostex T500Mk2.

For HF Pham uses Mewon Ribbon TS01 in both cases. I do not know what it is. On the picture it looks like a wide ribbon, something that would be more suitable for lower crossover point, but you never know…

In either case the channels are not time-aligned and use with random lateral offset. I presume that timing is done by digital crossover, if not then this installation is just pile photogenic garbage. It would be interesting to see Pham’s choose for amplification for each channels and if he used DSET techniques and optimized in any way his DIY ams for specific channels, and if he did then how.

In my view the biggest concern of my in this installation is a lacking of upper-midbass channel.  Pham use the JBL 4344 box and I in my estimated he drivers a LOT of power over it.  I think the upperbass/midbass horn is what doctor order for this playback. He has that larger curved 75-80Hz horn that is currently is wasted for that Westrex T530A compression driver with 400Hz cut off. I think if Pham load this horn with something of those Japanese compression drivers that can go for 60-70Hz    then he will take a full advantage of that horn. Of cause then he will hit that “70Hz horn syndrome” when the horn is too bit to be located under HF but there is nothing to put in there… Well, Pham is not alone with it….

That were my thoughts that I had what I was looking at Pham installation…. If someone know him then bring his in as I would like to hear about his thoughts regarding JBL 375 and SG-370 differences, about Fostex T500Mk2 advatage and about use of Fostex 30” in THAT horn.

Rerurn to Romy the Cat's Site