Van Alstine Ultimate 70 vs Puresonic Quadramatic 410C

hotroady · « **on:** 30 Jul 2008, 07:33 am »

I preamp ed both units with VanAlstine Pat5 SS preamp. The U70 is a keeper, decent power @35w rms per. Clean, sweet highs, tasty mids. Soundstage; better than most! Bass is good for tube, it goes low and full lacking control in damping. Damping factor probably around 9-9.5, my guess...as compared to factor of 10, rated for Fisher X-1000..which I have also compared with, and found to be slightly better at control of bloom. Decay and attack. The Puresonic is a 1965? unit not fully revamped, but freshly serviced w NOS plug in 500v caps installed. Appear to be original Japanese EL34's. Quadramatic includes auto bias feature, among its sophisticated circuitry. Fantastic soundstage! Crisp, but not clinical..even more detail than the U70. I rate the X-1000 more musical than others at mid-highs..it has 55w rms per..new set of output tubes, so more authority present with Martin Logan Clarity's being driven. The electrostats are very revealing, even at low volume listening. I had my friend come over to listen..he said he really liked the sound of the center channel Logos. He was familiar with my set up w three channel Fisher. The only thing was...It was not hooked up to Anything, nor plugged in. It was that soundstage, he heard! He had listened to the U70 plenty of occasions, never a thought it was coming out of center channel speaker! I would say the Puresonic is more balanced over the full spectrum. Its damping factor is 181..best of all amps..back in '64. It had less bloom, better control of bass cones. I set up my Klipsch RF-83's w bi-wired 8ga. stranded welding cable leads attached to woofer lugs. Idea being less resistance to control the woofs. Four twisted 14 ga. 600v solid core wires control the tweets. More skin effect, less conductance between strands, but flexible enough for transport and hook ups. People needed to sleep, but apparent at low level much greater cone motion control over the three 8in cones in each speaker. Really looking for fast tight bass out of a tube amp. I believe I have found my Holy Grail in the 410C. I will update when I am able to crank it! I am also waiting on my Puresonic tube preamp..seems it went into variactic arrest shortly after being arrived. The old boys...including my tech..loved it while it was alive. Cap surgery most likely. Tech loved layout of preamp, but finds amp hard to get at. He hates working on Mac's for same reason. Heralds materials and build quality, though. 42w rms per, less than .05 distortion at any point. IM about non existant. Wonder how it will sound with quality set of tubes? The Fisher was of coarse driven by its internal pre section, Can't wait to hear difference with matched Model 112 pre, for Puresonic. I suggest grabbing one, before someone realizes their inherent value. Not going to say what I paid, but I let the cat out of the bag, now. I'll look for more...but not THE Dizzy Gillespie unit on Ebay! I think he came down to 2500 for 112 and 402C pair. I feel certain same guts as 410c..if you look close at the tag shot..it reads 410C..the front layout is different, than mine. Well let me know if this piques anyone's interest, huh? Ok update, found out tonite..four Valvo 12ax7's(83's) inside, connected in parallel hence the Quadramatic name. so that's what accounts for all that air and soundstage! Found loose connection on one of a pair of GZ34 rectifiers tied together to serve as one full wave rectifier. Tightened the pins, one was Mullard, will have to look for another as match, but the Sovtek in the other works fine in conjunction. Opt trannies are Dyna 70 size, with huge power transformer. I would say the U70 has a warmer midrange, but will See what happens, when tube preamp is in place. Just had fat bottle EL34EH's for outputs, Changed out to 4 fat bottle GE's. Discovered I have 2 Mullard made XF4's...need to find 2 more..hint, I'm looking. I switched out the Martin Logan's Clarity's I was listening to, back to Klipsch RF-83's. The three 8in woofers are ideal for tube amps and the fast bass I want, Sounds even better w GE's. Really wonder what would happen if I put one of the locale's DAC's in play. We have some pretty good locals..AR, Bel Canto, and of course Van Alstine!

kyrill · « **Reply #1 on:** 13 Aug 2008, 04:01 pm »

hi hotroady

thx for the info
it is not yet a review?

It was very hard to read for me because of the format. You choose to let all the sentences to become one
massive string..

hotroady · « **Reply #2 on:** 15 Aug 2008, 03:08 am »

Quote from: kyrill on 13 Aug 2008, 04:01 pm

hi hotroady

thx for the info
it is not yet a review?

It was very hard to read for me because of the format. You choose to let all the sentences to become one
massive string..

You're right, I reformatted, and have been experimenting, so I intended to update. I installed ganged banana plug sockets which fitted into existing 3/4in CtoC holes. Found output wires to be 24ga solid core "doorbell" wire. More so, the transformer wires are solid wire! About the only stranded wire was power cord. I think this may be part of the reason this amp is focused on the top end. I decided to go to 18 ga solid wire...resulting into too much brightness, and killed the midrange. These are up to 21/2 ft runs from volume pot to rear connectors. Bummer! Next up..switched to 16 ga stranded wire. Yeah, that's better, much better. Notes are fuller..has picked up some of the musicality the Fisher has! I have to say..the U70 has the best midrange...I switched back to it, to make sure I wasn't imagining things when I first switched to 18ga. Man, that 18ga solid, was fatigue...sounded like a harsh SS amp. Jeez, if I could only figure a way to boost the midrange a tad. Wonder if I could utilize a set of Sansui transformers? I am very happy with changes as is. But I got the illness and want more.

kyrill · « **Reply #3 on:** 15 Aug 2008, 09:43 am »

Be aware of that illness, it does not recognize when to stop..

crooner · « **Reply #4 on:** 5 Sep 2008, 03:52 am »

Some pictures of the Quadramatic please!

Never seen one in the flesh. With today's digital photography I'm in for a treat!

hotroady · « **Reply #5 on:** 5 Sep 2008, 05:29 am »

Hi crooner. Yeah I will do that. Right now thick into setting up a DJ system w DAC, mixer, computer, Masterlink, and using the quadramatic for the amp! Hard to figure out, but have to get it up and running. I did try some 5751 Amperex NOS matched 1963 quads in it. It did bring out the midrange and bass is strong ! It also moved the soundstage back, highs are rolled off, piano is flat, so are bells, horns. Just not crisp or forward as it was. On the other hand it sounds sorta like good live FM, probably great for jazz or romantic music. Bass is better than the U70, midrange close, but much better clarity w the U70. I do like the sparkle that the smooth longplate Telefunken;s provided, I will use them in the DJ system. As you probably know, crooner..the Quadramatic was direct competion for 8B. I imagine you are curious to see.

crooner · « **Reply #6 on:** 5 Sep 2008, 05:40 am »

Those are rare my friend!!!
The preamp is also interesting because it uses Compactrons.

Indeed, Pure Sonics wanted to compete with Marantz.

The brushed aluminum front panels are reminiscent of Saul's products.

I think they pushed vacuum tube technology to the limits back in '64. Pretty daring and innovative designs.

The lifetime warranty was unprecedented. Too bad the company went under fast.

hotroady · « **Reply #7 on:** 5 Sep 2008, 05:50 am »

Surprised how much you know about it ! Mine is a really clean unit, so is the preamp.

crooner · « **Reply #8 on:** 5 Sep 2008, 06:10 am »

Quote from: hotroady on 5 Sep 2008, 05:50 am

Surprised how much you know about it ! Mine is a really clean unit, so is the preamp.

Well, I have always been interested in the lesser known high end audio companies during the last years of the vacuum tube era. Just before solid state devices appeared on the scene. This would have been 1964 and 65. The competition was fierce and not many survived. Pure Sonics was one of the most adventurous.

Hadley is another one of those companies.

I have a review of the 402C in High Fidelity magazine and an ad featuring Dizzy Gillespie. I'll try to scan and post them here...

crooner · « **Reply #9 on:** 5 Sep 2008, 06:30 am »

Here's the Quadramatic ad:

And a PDF of the review in High Fidelity (March 1965):

Quadramatic 402-C Review

I think the review was lukewarm at best, which did nothing to boost Quadramatic sales.

They mentioned instability with electrostatic and "inexpensive"? loudspeaker loads and a hump in the IM distortion measurements around 20 watts. The design apparently did use a lot of feedback. The damping factor of 181 was unheard-of back then!

hotroady · « **Reply #10 on:** 30 Nov 2008, 12:06 am »

I got my Model 112 tube preamp in circuit now. Didn't expect such a change. I think it has 8 tubes, and their all triple triode. The 410c, now has balls. I am driving Martin Logan Clarities, which is a hard speaker to match up with..it has 6ohm woofer and goes all the way down to 1.1 ohm impedance. The amp handles it just fine. The Clarity have an upper bass diffusion problem giving it a 'rubber membrane' timbre. I installed a cross brace that also pins the port from deflecting. I also removed all fiberglass matting, I will continue to experiment, but it's tighter in the Mids, but not as low in the bottom. I was looking for a way to better match my sub to this speaker. Playing w crossover point and using 'music' output dialed down the sub. It now sounds like the bass is coming from the speaks. Much tighter bass, with reduced overhang. Mids and bass are noticeably improved. With the preamp, the Pure Sonic might even better the U70 Mids, and leaves it in the dust in bass region and upper. I will put the packing back in the one modded speak, and give it a listen. Very satisfied so far.. Boy bad recordings sure are noticed, but a tad more livable, now. Too make a long story, short...I eventually found a phase setting on the sub..then the midrange just snapped into place. It was kinds thin and stringent compared to the U70, now way warmer..this is what tubes are all about !

hotroady · « **Reply #11 on:** 7 Dec 2008, 05:17 am »

I have pics to post now, but how do you post on here?

crooner · « **Reply #12 on:** 7 Dec 2008, 05:35 am »

You have to host them yourself I believe. I use my own webspace provided by my Internet Service Provider. Other folks use services like photobucket and flickr.

hotroady · « **Reply #13 on:** 7 Dec 2008, 08:13 pm »

http://s428.photobucket.com/albums/qq1/hotroady/?action=view&current=IMG_0088.jpg I don't really know how to get pics here...all chinese to me.

JerryM · « **Reply #14 on:** 7 Dec 2008, 08:54 pm »

Quote from: hotroady on 7 Dec 2008, 08:13 pm

http://s428.photobucket.com/albums/qq1/hotroady/?action=view&current=IMG_0088.jpg I don't really know how to get pics here...all chinese to me.

Hotroady,

Here ya' go!

crooner · « **Reply #15 on:** 7 Dec 2008, 09:19 pm »

Very interesting pieces!
I like how the power amp matches the preamp in appearance. The earlier 402-C did not.

hotroady · « **Reply #16 on:** 7 Dec 2008, 09:53 pm »

Thank you Jerry M ! Info is so hard to come by on the Puresonic...it deserves to be reintroduced to the audio world. Crooner, Yeah, I don't like all the speaker hook ups on the front of the 402C. I think the 410C and Model 112, look pretty modern and sleek for tube equipment of the era.

crooner · « **Reply #17 on:** 8 Dec 2008, 12:41 am »

Yeah, I think the Quadramatic stuff deserves to be rediscovered.

The build quality of the preamp is excellent and the use of Compactrons unprecedented. I'm guessing it shouldn't be too expensive to retube...

hotroady · « **Reply #18 on:** 8 Dec 2008, 03:11 am »

I wonder who the designer was? Maybe (he or she) is still around? The pre really made the difference w the amp. Now, I wish I had an 8b and pre to compare to. Bass is superb as they claim. Mid opened up so much when I got the phase right. Now the mids on the Clarity w sub, are deeper, prominent, warm and sweet. Mids were thin and a little stringent before I hit on this set up. Not sure how you guys get pics to post here, but thanks. Who would have thought up Compactrons? All the preamp tubes are triple triodes! They appeared to use very high quality parts, no skimping. Nice little stack of plates on that little transformer huh?

hotroady · « **Reply #19 on:** 14 Dec 2008, 11:52 pm »

Sprague 40 MFD twist loc caps are stock.