Discussion in 'Dollars and Sense' started by Chrisxo55441, Nov 11, 2016.
It is not a deal price but it is also not an overprice. 16000 is the right price.
I could settle for a pair of McIntosh MC75 instead.
i did find a pair arrived tonight , triple boxed safe and sound and bit cheaper then the ones in this post but not mint but in excellent original condition. will power them up tomorrow after i test the tubes.
Congratulations! Looks like an early pair without the heat shield for the output tubes. Please report back with your impressions.
I have just wrapped up tonight's listening session, and I'm in awe of their sound just like the first time I listened to them!
Thanks the serial numbers are 9-1376 and 9-1416 is that an early pair ? is there a difference between early and late models?
Yes, yours are probably from 1961.
According to Kevin Hayes of VAC, there was a change in the output transformer at serial number 1500, although I haven't seen any reference to this elsewhere.
By visual observation, I can tell the early amplifiers do not have the neon safety lamp for V3. The lamp is used to protect the grids at turn on.
they look pretty good for 56 years. i didnt know there was a production change and didnt notice the heat shield until you pointed it out the serial number location changes from the top to the back as well. i wonder if there is really any noticeable audio difference. i will run them with the cages off and a fan on the tubes same as my 8B anyway. now i need to decide if i want to have them restored or not. the tube tech who i use and trust could be retiring soon so that weighs on my decision.
You could also ask the audible differences between the 8 and 8B. Could be that tube options would swamp them.
Fwiw, I'd definitely have the NE-2s added during refurb.
I think the Model 9's before S/N 1500 are a "test run" of sorts, just like the first 100 Model 10 tuners. They probably had limited distribution to certain customers/dealers to get a feel for the product.
You can also note they have rivets or screws on a plate where V2 was supposed to go. This is the extra tube that was eliminated in the final version of the circuit.
Saul Marantz has been quoted as asking Dick Sequerra to help Sid Smith release the Model 9 right after he was hired. And Sequerra's first contribution was the heat shield and the measurements set which he helped devise. So this seems to be confirm the early amps without the shield were pre-production units of some sort. The absence of the neon lamps confirm this also.
I would be interested to know how stable your amps are compared to the 8B. Being push-pull parallel, you have twice as many tubes to contend with. The d'arsonval bias meter on the Model 9 is more sensitive than the one in the 8B, so keep that in mind when assessing bias stability.
I'm just a hobbyist of sorts, so take this with the usual crystalette of sodium chloride. The thing I see with the 9 and 8B is considerable effort to make them unconditionally stable at maximum safe power output, with no reduction of ultimate SQ.
Yes agreed. That explains their obsession with multiple independent feedback secondary windings, trimming caps and plate inductors to combat parasitic oscillations.
is this a good thing or bad thing or it doesnt matter ? im not a tech either so i dont know about bias stability but i can bring them to the tech i use and have him check them out probably would anyways given their age. should i check the bias more often to see if its drifting and adjust?
I don't think it matters much as they sold quite a bit of them back in the day (perhaps 200 pairs?). I see them for sale all the time. It was a big roll out compared to the Model 10 tuner.
Have the tech check the plate inductors (two per amp). In my pair they looked like they overheated at some point and I ended up replacing them. These are key for the stability of the amps.
I have also noticed one of my amps is a little more bias stable than the other. I don't know why this is the case. It sounds great, so no issue there.
I used to obsess about making minute adjustments to the bias but I have found this is not necessary. Once they are warmed up for an hour, just set the bias and forget it. Check monthly.
The amps will sound fantastic without having to dial the bias perfectly. They are heavily biased towards class A, so there's plenty of leeway.
I definitely recommend triode mode. The purity of the sound is unmatched and 40 watts is still plenty except for the most inefficient speakers. My LS3/5A's sing using the 16 ohm tap.
You are the best thanks for sharing all the knowlege. i will try triode mode with my Tannoy Cheviots and Fortes but im hoping to use these with my Ohm Walsh 4's which are 6 ohm and use the 4 ohm tap, is there any problem with that?
Should be OK. It's a question of finding the optimum impedance match. I would try both the 8 ohm and 4 ohm taps and settle for the one that provides the least distortion, specially near or at the clipping point. That may pose a challenge since these amplifiers clip so softly! But overall, whichever tap provides the "magic" is the right one, and you'll know immediately.
Now, theoretically the 16 ohm tap should provide the best sound (with an appropriate matching speaker) since you are utilizing the entire secondary winding of the output transformer. This is why some folks favor the older speakers and electrostatics which were often 16 ohms in nominal impedance. The BBC designed LS3/5A has a nominal impedance of 15 ohms, which comes very close.
tested the tubes ( very strong xf2's O ) set the bias and ac/dc and fired them up last night. first impression was that i wont need to turn the heat on in the listening room this winter these suckers throw out the heat hooked them up to the tannoys for now because they were up front and easy to get to, my 7C has a right channel issue that i need to get fixed so i hooked them straight to my icon audio PS1 mkll phono stage which has a volume control, my 1700 mk2 with AT 150MLX was on that and i put on my favorite LP Albert King Truck Load of Luvin and left the amps in regular mode ( 11pm and i get up at 5 and go to bed at 9:30 so i wasnt sharp lets say ) sounded excellent seemed a bit bright but great bass response, switch to triode mode for side 2 and everything smoothed out wasnt bright bass even improved then i fell asleep about the second song so the only thing i can tell now is that they work. will do some critical listening today hopefully. maybe try using my EAR 834P phono stage which has volume control also and try my AT 50ANV cart. and i need to get my 7C in for service asap
I'm glad the amplifiers are up and running and sounding great. I find mine to be very smooth & sweet, almost to the point of sounding too mellow. However, with recordings that have cymbals, bells or other high frequencies, they sound crystal clear, so the highs are there. They just don't impart any artificial "electronic" crispness to the sound, which is quite startling when you first listen to them. Their natural mate is of course the Marantz 7c, so your mileage may vary if other preamps are used.
The XF2's are the way to go with the amps. I also find the Siemens RFTs sound superb on it.
I agree they heat up the room, but the transformers themselves and chassis run very cool if enough ventilation is provided.
If you need to run a fan, make sure they are extracting air rather than blowing air on the tubes. Better cooling this way as you are pulling the hot air away from the transformers and chassis.
Also, the triode switch cannot be actuated "on the fly", the amps need to be turned off.
Attached is a pic of the my amps playing this morning...
i have 10 NOS RFT (same codes from a factory box) in the vault along with 10 NOS XF2 double getters waiting and another 5 set aside for the 8B as well. plus a bunch of XF2 and XF3 single getters so they should last longer than i will.
oooops didnt find any info on that thanks i will know better in the future seemed to change the sound when i switched it though but i was pretty much asleep on my feet, i turned the gain off first before switching
thats a sweet set up do those LS3/5A give you enough bass or do you have a sub hiding somewhere?
Yes, there is no info on that, not even in the manual. Activating the triode switch on the fly will produce a loud pop from the speakers and the high voltage switching is not kind to the vintage irreplaceable output iron. The switch contacts will carbonize and fail eventually also.
As for the LS3/5A's, they are running full range. I find the bass to be more than enough for my taste. For most commercial pop/rock and acoustic jazz they do just fine. Even classical has enough weight and presence. Sometimes I am amazed to pick up recording venue rumble, footsteps, air conditioning and other low frequency sounds on them.
RCA's legendary Pines Of Rome/Fountains of Rome recording by Reiner blew me away the other day, specially the last cut "The Pines of Appian Way" . the low frequencies are pretty amazing on that one. I can't believe these little shoe sized boxes are capable of such sound!
The BBC minimonitors were my main and only speakers for a three year Army tour in Germany.
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