Home Vintage Asylum

Classic gear from yesteryear; vintage audio standing the test of time.

Update for Interstage Tranny and all...

I thought I'd offer this update... It's now 4:30am and I can't drag myself away from the Home Theater system. I've been listening to digital MusicChoice or MTV Hits, which is a much higher quality signal then the usual music video channels.

I finally started my migration to building the tri-amped setup, starting with finally firing up the Dukan and NTS amps. I'll sum up my feelings by saying I feel compelled to visit the Klipsch appreciation thread on AudioKarma where I avoided the "must be tubes" debate, to add my $0.02 to support "must be tubes"; at least that's so for the La Scala given tonights experience.

I had been using the La Scalas 1st with the built in Onkyo 939's amps. Wore that 5-ch chip-amp out. Bought a Butler 5 channel, which is a 'typical' hybrid, with a tube front-end and bi-polar back-end. Nice step up; but lacked 'brilliance', punch, and some clarity/depth. Was kinda analytical and dry; and harsh-ish if the signal wasn't perfect. Did a smashing job with reproducing my new favorite of the Cream DVD @ Royal Albert Hall as it is a great recording and clean. But still, something's not 'perfect'.

So first, I setup the Dukanes 1A475 amps (I was distressed to realize one is a 'C' and one was a 'B'! The 'C' has more gain). Youza. Can you say punch and bass?! I was -really- surprised. Highs were noticably subdued. The Cream DVD was even 'realer' then usual and less fatiguing. This amp I understand is from the early 60s; and just a 'PA' amp? Well, I could agree with the latter given the 'liveliness' of the reproduction; but still very much 'HiFi' too!. But most notable compared to the amp I was coming from was how 'dampened' yet rich the sound was. It was incredibly less congested then the modrun highly rated Butler amp I had been using with the La Scalas. However no doubt, much 'crunchier' sounding too. But in a good, nea, great way.

I then finally setup the Bogen made National Theater Supply 1125 125watt 807 output tube amps... (this, being the amp made in the late 40's with 6 x-formers I discussed in a different but similar thread some liek Interstage Tranny have participated in... the eBay seller said 5; I found the 6th hiding under the chassis ) Since I was bringing the amps up slowly, I did one at a time, using one Dukane and one of these. This amp must have a low impedance input, as I had to boost the signal +13db from the Dukane. The tonal balance was very different though too, and I couldn't really listen with one and one amp mixed. This amp was definitely lighter in the bass.

When I switched the other channel to the 807 amp too, the Dukane's deficincy on the top end really became apparent. More amazing still though was how much better the La Scales responded throughout the whole frequency spectrum to this tube amp (that's not to say it wasn't the same with the Dukane; I'm saying both mate so much better then the Butler). And how much better the treble was! (I'm using a JBL 2402 driver with a mini-smith horn tweeter instead of the stock tweeter) Clear and crisp. And how much more cohesive the upper mid to treble was. Shocked I say! And though bass wasn't as strong as the Dukane, this was a much tighter cleaner bass. Interestingly, I had to flip the 2 M&K Subs phase 180 degrees then how I ran them with both the Butler, and with the Dukane. [!!!] It's also tough to say, but there might be a bit more congestion then the 1A475 amps though; perhaps though only because the Dukanes are so 'dampened' sounding in the presence and above. But the tone is just so pleasing I can't deny it. The upper harmonics of Jack Bruce's bass guitar came through better with this amp then any of the others I've used.

I could definitely live with 4 more of these 807 output tube amps, for use with both bass and midrange on all front 3 speakers. Not being likely, and where I was 1st planning on using the 807 amp for bass up to 500 and Dukane between 500 and 7K (or there abouts), I think I'm going to do it the other way around now! Dukane for bass, and Bogen/NTS for midrange.

I'll add, the NTS amps have had some caps replaced. The Dukanes don't show any evidence of being updated. So that's definitely called for. The PS filter caps are necessary on both IMO. But I am content in the knowledge that I have two great examples to build ontop of.

Coming also is a couple of Bogen MO-100 amps; one a mess; one in working order. Super simple circuit; easy to support and upgrade. Should work great for bass on the center; mid may be that rare Arc M-60C ... maybe. Arc techs tell me it's not very reliable and to stick it on a shelf and not use it... :( So I might use another bogen ... what I really want is another 807 output tube amp like the NTS! I know a guy who might be up for building me one... or four. Figuring out the circuit without deconstruction will be tough I think though.

OK, I digress. To sleep finally...


This post is made possible by the generous support of people like you and our sponsors:
  Analog Engineering Associates  


Follow Ups Full Thread
Follow Ups
  • Update for Interstage Tranny and all... - m8o 01:40:03 04/08/07 (0)


You can not post to an archived thread.