Vintage speaker haul this week-Polks, Mcintosh and KEF

downhiller2010

WHEW! what good luck this week. Picked up Polk RTA-12's one speaker has shifted magnets though. Grabbed a pair of Mcintosh ML-10C's as my next project and these things are absolutely beautiful. Lastly I grabbed a pair of KEF 104ab's. Less than $150 spent overall. I am for sure keeping the Mcintosh and Polk's. The tough question is do I want to sell my monitor 10's with RDO tweeter or the KEF's. The KEF's seem to need a TON of power. What would you do?

cnh

Some nice finds there. I've never seen KEFs that look like that. Any idea what time period we're in there? I'm assuming that race track (LSiM bass looking speaker?) is a passive radiator. Interesting to see designs like that so "early". I'm assuming this is a fairly old speaker.

As for what to sell. You got me there. I have some Monitor 10As and I can't "ever" see selling those, myself.

Enjoy.

cnh

downhiller2010

Yeah, I love em enough to put the RDO's in them, but the RTA's from my initial 15mins listening to the one that is working sound so much more clear and crisp and not as boomy as the 10's

teekay0007

Congrat's on some nice scores there!

"Boomy" 10's? That's the first time I've heard that. And not as clear and crisp, even with new RDO's, as RTA's with one having shifted magnets? Hmmm...something doesn't sound right about this! Are the RDO's broken in yet?

Don't ever see myself selling my 10Bs...:cool:

mhardy6647

The KEFs are the real bonus there; wonderful speakers.
FWIW, I'd opine that both the 10s and the 12s have a somewhat midbass heavy or thick sound (I like to refer to it as "phat") - it's not unpleasant, but not all that accurate either. Over the decades, I've decided that for my own ears and tastes the somewhat "leaner" sound of the Monitor 7 family is preferable (and, I daresay, a notch more 'accurate', although that's not stated as an absolute fact; never measured them head to head).

Mr. Bubbles

I have a pair of the 12's un-modded and like them a lot. But if I understand correctly there were some changes made to the 12's (A's/ B's) that made a pretty significant difference in their sound with the later models having specific left and right designations. Maybe someone that knows more about them can tell more.

If it were me i would clean the Mac's up and repair as much as possible on them for a s little as possible and sell them. people pay STUPID money for that stuff and I have never heard any of it that sounded better than other gear that I have heard. (granted i have not heard any of the Mac tube gear but i would doubt it sounding better than a Marantz 9 (which also brings crazy money)). I am not familiar with the Mac speaker but just guessing from the paper cone tweet in them that they will not give the sound of either the Kef or the Polk. I would assume the Kep to be the best of the lot here.

I would just like to note the Marantz gear (turntable and receiver) looks good. i am a huge Marantz fan but it doesn't seem to like any of my Polks as good as other speakers. I think the vintage polks with large cabs and passives need a little more control in the bottom end than the Marantz affords.

Sweet haul. Enjoy, and congrats.

downhiller2010

Nice eye!, It's a recapped 2245 and a marantz 6300. I'm buying a new rack today so I'll probably get some good setup ictures together soon.

downhiller2010

Has anyone ever done diy top hats for the RTA's?

Joe08867

Those KEF's are awesome speakers. I would love to have them. And yes they need a good amount of juice to get them going.

They look just like the Kit KEF sold. Here is some info for ya, 104aB Cantatal

Model 104aB Kit (1979-81)

In the early 1970s KEF invested heavily in digital technology to assist the design and manufacture of loudspeakers. Using computers to control acoustic measurements allowed data to be stored in a form that significantly aided the design process as well as forming the basis of an advanced production quality control system. The first loudspeaker to benefit from this was the first of the new Reference Series, the Model 104.

Model 104 was an 8 inch two-way system with an passive radiator augmenting the low frequency response, a format that was developed previously for the Cadenza system. The B200 bextrene coned bass driver for the 104 had a short coil/long gap magnet system for low distortion and the system included a three position acoustic contour control, which allowed +/-2dB of midrange level adjustment.

In 1976 the system was updated into the 104aB, where aB stood for ‘acoustic butterworth’, relating to the shape of the acoustic response of the midrange and treble drivers in the crossover region. Perfect integration of the units will only happen if the acoustic responses of the two units conform to a precise characteristic. Previously, crossover filters had been designed primarily on the basis of the electrical response of the filter but, in reality, the acoustic roll-off is also a function of the natural roll-off of the driver response. By considering the filter and driver as a combined system the filter response can then be optimised to give the precise acoustic roll-off necessary for perfect integration.

The Model 104aB Kit was available to those who chose to build the Model 104aB components into their own enclosures. Supplied with drive units ready assembled onto the lacquer finished baffle with all electrical connections made.

erniejade

Shame on the missing woofer from the McIntosh speakers. I think if memory serves me right there was a processor for them as well.

The kef are a hidden jem! Before you get rid of them, give them a good long hard listen. You might be suprised!!!

You got one heck of a haul for the $ you spent! Nice find on all of them!!

Mr. Bubbles

downhiller2010 wrote: »

Has anyone ever done diy top hats for the RTA's?

I have to do this at some point myself. I have had some help with descriptions, measurements, etc from another member here but haven't started yet. I don't think it will be that complicated but there is a reflector built into the top hats that i have seen pictures of. Some of the 12's have a different tweeter mount than yours. Mine are mounted on a baffle and positioned horizontally instead of vertical and the baffle has a deflector mounted to it under the tweet. From what i understand the deflector in the top hat aligns with the deflector on the tweeter baffle deflector, so I'm not sure if it would be pertinent to your speakers or not. Again maybe someone else with better knowledge of this model will chime in and explain these better to both of us.

downhiller2010

erniejade wrote: »

Shame on the missing woofer from the McIntosh speakers. I think if memory serves me right there was a processor for them as well.

The kef are a hidden jem! Before you get rid of them, give them a good long hard listen. You might be suprised!!!

You got one heck of a haul for the $ you spent! Nice find on all of them!!

It is not missing! I had already pulled it actually.

cnh

Great info on the KEFs, Joe!

Cone tweeters. There were some "very" fine produced in the day. I know because I have some!

I've compared my Monitor 5As, which certainly no one can say are dark or bloated, to my 10As and I just can't "hear" what some of you are talking about. The Midrange is not radically different, the bass is NOT uncontrolled on the 10As. These babies can rock and still sound quite good. I guess I just have to hear the 7s, but SURELY, they can't be MORE coherent than the 5s which are smaller and arguably at least as tight and smooth with less bass?

KEF's look like a winner. But I have to say that the woofer on that speaker looks unbelievably like some later Boston Acoustic 8" drivers. Remarkably like one, in fact!!

cnh

downhiller2010

Interesting, I pulled the frozen drivers out of the one pair of RTA's and one is a MW 6500, the other has a MW 6501 label, but the one is sharpied over with a zero?

mhardy6647

ummm... KEF did the "racetrack" woofer first; and indeed all three of the KEF drivers in those 104abs are true classics.
In fact, it was the KEF, Spendor, and Rogers speakers of the early 1970s that Polk Audio quite explictly and deliberately paid tribute to with their significantly more affordable "Monitor Series" loudspeakers.

cnh, ever hear any of the IMF speakers?

imf%20monitor.jpg

I used to have a pair courtesy of my favorite local vintage electronics emporium :-)
Quite KEF-like, with aperiodically vented cabinets. Quite sensitive and to-die-for "British Monitor" tone and midrange.
I moved them along to an AK colleague in partial trade for a bunch of Nikon camera equipment and lenses. Hard as it is for me to get rid of anything - it really was a shame for the IMFs to be tucked away in the basement gathering dust than singing somewhere.

drumminman

FWIW, I'd opine that both the 10s and the 12s have a somewhat midbass heavy or thick sound (I like to refer to it as "phat") - it's not unpleasant, but not all that accurate either.

My modded RTA 12C's sound to my ears very flat, very accurate. I rebuilt the Xovers, rewired the speakers, installed Black Hole 5 in addition to the original batting, and changed out the driver mounting screws with Hurricane nuts and SHCS's. Though they can be driven by modestly powered receivers/amps, they don't come into their own until you put something with authority behind them. Though mine are far from stock, I bought them new to replace ADS L-700's which had a reputation as an accurate speaker for the time. I found these to be more so.

I have a pair of the 12's un-modded and like them a lot. But if I understand correctly there were some changes made to the 12's (A's/ B's) that made a pretty significant difference in their sound with the later models having specific left and right designations. Maybe someone that knows more about them can tell more.

The speakers pictured are the original RTA 12's (not B or C). You are correct that the Xovers for the later models were redesigned and there is a designated left and right speaker. The MW's operate in different parts of the frequency spectrum with one covering low range and the other a much wider range, though I can't remember the numbers. If you set the speakers up on the wrong sides (right on left, etc.) the sound stage collapses and it all sounds like s__t! Set up properly they image amazingly well, with a strong center stage, powerful tactile bass, liquid mid range and open and airy highs.

There are a couple of RTA 12 experts here on the forum. Hiopefully they can add to this.

mhardy6647

drumminman wrote: »

FWIW, I'd opine that both the 10s and the 12s have a somewhat midbass heavy or thick sound (I like to refer to it as "phat") - it's not unpleasant, but not all that accurate either.

My modded RTA 12C's sound to my ears very flat, very accurate. I rebuilt the Xovers, rewired the speakers, installed Black Hole 5 in addition to the original batting, and changed out the driver mounting screws with Hurricane nuts and SHCS's. Though they can be driven by modestly powered receivers/amps, they don't come into their own until you put something with authority behind them. Though mine are far from stock, I bought them new to replace ADS L-700's which had a reputation as an accurate speaker for the time. I found these to be more so.

Indeed, you added weight to my point, because I referred to the speakers as Polk built and sold them, not tweaked ones. Thanks for the amplification (pun only sort of unintended). Heck, one can even make Klipsch "Heritage" loudspeakers sound reasonably good (search "Crites" or "ALK", e.g.)... but there's not much left of the original PWK design or product but the box as the end product.

It's a credit to Matt Polk & company that they build good sounding loudspeakers at essentially bargain prices in their early days... but the bigger "monitor series" were built to appeal to a sound aesthetic of their time, as reproduced on the electronics and sources of that same era. They ain't bad... but they had some... coloration relative to really accurate reproduction.

I have no doubt the mods improved this markedly.

EDIT: I haven't logged much time at all listening to the ads L-700, but I own a pair of L-710s and I'd characterize them as extremely neutral if somewhat polite sounding loudspeakers (again, stock). About the only more consistently easy to listen to loudspeakers I've ever heard (nigh-on 40 years of fairly serious listening) are the Quad ESL-57s (again, talking stock).

downhiller2010

What is the right crossover schematic for the RTA's?

cnh

mhardy6647 wrote: »

ummm... KEF did the "racetrack" woofer first; and indeed all three of the KEF drivers in those 104abs are true classics.
In fact, it was the KEF, Spendor, and Rogers speakers of the early 1970s that Polk Audio quite explictly and deliberately paid tribute to with their significantly more affordable "Monitor Series" loudspeakers.

cnh, ever hear any of the IMF speakers?

imf%20monitor.jpg

I used to have a pair courtesy of my favorite local vintage electronics emporium :-)
Quite KEF-like, with aperiodically vented cabinets. Quite sensitive and to-die-for "British Monitor" tone and midrange.
I moved them along to an AK colleague in partial trade for a bunch of Nikon camera equipment and lenses. Hard as it is for me to get rid of anything - it really was a shame for the IMFs to be tucked away in the basement gathering dust than singing somewhere.

No, I haven't heard any IMF. And until you mentioned them I had no idea what they were. But I'm thinking, after a little googling that that is a Super Compact! A peerless tweeter and doped mids (Polk?)

It goes without saying that the Rogers speakers, all two models that I've heard have been very impressive. I would have no problem picking up a pair of those.

So many speakers. How do you all keep track of them? I have a system for movies, as my best friend is an Indy filmmaker, so I just hang with him or call and he keeps me informed. And as for "new" music, I have a 14 year old (this system of proxies works incredibly well and saves me from having to spend "half" my life attending to hobbies I don't have the time to master.

This forum helps there as well! Now I know that IMF can mean more than International Monetary Fund. lol

Thanks!

cnh

mhardy6647

It can mean (American) Irving M. "Bud" Fried... even though his connection with the British company that bears his initials was tenuous (or at least, complicated). He sold his own speakers, US made, under his own name as well (i.e., Fried) - another one of those interesting hifi speaker company stories (cf. Klipsch, Polk, Cizek, AR/Allison/EPI/Genesis/KLH/Advent/Boston Acoustics/Cambridge Soundworks/Tivoli, etc.)!

Super Compacts they are indeed... and they are fine sounding loudspeakers from top to bottom.

PolkieMan

I got some Monitor 4a off ebay for 12.50 + 20.00 shipping the auction ended at 12 midnight and the seller had only 1 feedback as a buyer and the picture was quite blurry so I was a little worried... but they came fedex 3 days later rolled in bubble wrap in a big box and they are mint and I mean mint so much I was almost shocked

kkd

Nice score.

My two cents, I would keep the KEF's

downhiller2010

kkd wrote: »

Nice score.

My two cents, I would keep the KEF's

I did!