1951 Klipschorn Sound Reproducer crossover upgrade project

[tinpan]

I say crossover upgrade project because that is what it was turned in, a project, ha! I rescued this single khorn in 2016 off Clist, brought it home and tried setting up a mono system with it. I sourced a couple mono tune amps, tried them and they sounded horrible. The 6V6 based tube amps sound sterile with not much base. I sourced a cool EL84 based mono tune amp (Madison Fielding Series 12)and it had moments where it sounded glorious, exactly what I was looking for, then the bass would drop out, almost like a bad connection. Ended up leaving it in the corner and not really doing anything with it until recently when I acquired my holy grail, a Lowther Music reproducer. Wanting to use this Madison Fielding amp I tested in on a Karlson I have kicking around and it works fine there. Ultimately, I took it in to a shop to be reconditioned and bought another amp ( Sherwood) to use on the Khorn. Bass was missing so i decided to finally remove the crossover and send it to Bob Crites for rebuild. Course he had me check the Ohms  on the drivers and taht's where thing began to get squirrely. The tweete tested out at 4.2 which I thought to be low, The mid tested at 11.4 which confirms a 16Ohm Mid. The woofer tested at 2.6 which is also strange.

 

So what I thought was going to be easy peasy now is getting a little more challenging. Now I have to disassemble the speaker and confirm drivers so I can get the correct crossover rebuilt, which is why this thread. This speaker is actually looking to be a true 1951 speaker, The serial number indicates it was probably the real 242nd Khorn ever built and it is in excellent condition so I think it deserves to have everything verified and I will use it to build a true mono hifi project around it, featuring a Klipschorn Sound Reproducer. Interesting name, sounds an awful lot like a Lowther Hegeman Music Reproducer of the same vintage. I think Lowther had about 400 of these delivered by them so Klispch would be catching up.

 

I have done the research and have a lot of questions, for example, I wasn't able to confirm the finish and I'd also like to confirm what speaker components are used and the proper Ohms. I'd also like to confirm polarity for each component. The lamp cord used doesn't help. Seems all the terminals are marked 1 or 2 not - or +.

 

The tweeter is an Electorvoice  T35, with an Ohm reading of 4.2 whould that indicate 8 Ohm?

The mid is a Univerity Model SAHF. It's labled 16 Ohm and tests at 11.4 so the is pretty straight forward

The Woofer is a Jensen and I cma unfamiliar with it. It tests at 2.6

 

Hope you guys like pictures

 

 

 

 

 

 

 

 

 

 

 

 

 

Thanks in advance for your help

 

 

[Deang]

@JRH

[hanksjim1]

For what it is worth...the Jensen woofer looks to be original...shows a date code of the 37th week of 1951.  I have some later Jensen P15LLs ('66) that show a  DCR of 3.1 each (nominally 4 Ohm)

 

According to the Khorn timeline, the tweeter is most likely a later replacement for what would have originally been a University 4401:

 

"The first three-way Klipschorn incorporated a Jensen RP203 tweeter. This
tweeter came from the famous Jensen G-610 Triaxial 15" driver and required
considerable negotiations with Jensen. It was not until mid-1952 that all
Klipschorns were three-way. A two-way Klipschorn with response to 12Khz was
generally adequate for program material up to that time. The University MID-T-
4401 replaced the Jensen unit as the tweeter of choice later in 1951."

 

Is there any indication the upright center piece in the midrange/squawker horn had a tweeter installed inside like this pic?:

 

 

[tinpan]

Ah your suspicions are correct

 

 

Also, very helpful information confirming impedance on the woofer for me. Looks like 8 Ohm on tweet, 16 Ohm on Mid and 4 Ohm on woofer. Interesting combination

 

Anyone able to decipher the finish code 413F? I read through the ones listed on the PDF and didn't find it

 

Wonder what the chances are of finding a vintage Jensen 203 tweeter anywhere

 

Thanks

 

Robin

[hanksjim1]

Although Jensen did make a RP-203 compression horn tweeter...I believe the legendary Jensen 610 Tri-axial came with a RP-302 tweeter (regarded as one of the best vintage tweeters ever made)...maybe someone else could confirm which one came with the early Klipschorns.

 

FYI, Several RP-302s are currently on eBay:

 

https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2334524.m570.l1313.TR5.TRC0.A0.H0.Xjensen+203.TRS0&_nkw=jensen+302&_sacat=0&LH_TitleDesc=0&_osacat=0&_odkw=jensen+302

 

BTW,  I believe the RP-302 and the early University 4401s were 16 OHM.

[billybob]

Yes, 8 ohm tweeter...what is wrong with the T-35...it is akin to the K-77.

Thanks and nice mono when squared away.

[hanksjim1]

Interesting....this from 2009; a thread with a post by "khorn51":

 

"I have a few old khorns ( call it 7 ) and the best sounding stock twetter to me is theJensen RP-302 used on my 51. I thik they only used it on some 51's. I dont know why klipsch stoped using it might have been cost and very few recodings back then used the high info this tweeter could put out.

The university tweeter is ok sounding but I would pick the t35 over it, but theres not that big of a diffrence.

I use the orig crossovers in most of my 50's Khorns and have found all them still up to spec. Te old large can caps rarely leak or driff out of spec. If someone is making new crossovers that are the same specs as the 50's one thats news to me as the 60's and later are at diffrent points do the the metal mid horn bass slot ect. I like the way the older horns sound over newer ones. I have done a lot of a b using the top from my split lascals with new and stock a/ aa crossovers. the 51 is the smoothest sounding and my number one pic.

If you have the trousonic 15's dump them and send them to me,I'll send you some new k33."

 

and he later added this one:

 

"R P 302’s can be really big $$ if the seller knows what it is. The ones Klipsch used were the gold ones with the bullet shaped cover with bracket for mounting to the mid horn.. looks just like this one in link below"

http://images.google.com/imgres?imgurl=http://www.hifilit.com/hifilit/Jensen/RP302-2.jpg&imgrefurl=http://www.hifilit.com/hifilit/Jensen/Jensen.htm&usg=__Gj4hTpf7_Tr4iY3jGHV9mHCwmas=&h=813&w=1250&sz=179&hl=en&start=4&um=1&tbnid=MUiBUV88TNOi9M:&tbnh=98&tbnw=150&prev=/images%3Fq%3Djensen%2Brp%2B302%26hl%3Den%26safe%3Doff%26um%3D1

 

Here's a better link:

 

[tinpan]

Do you think the Klipsch Timeline PDF is a typo? Maybe they meant RP302? Also, I did find a problem in the original crossover, two of the spade lugs were slightly loose. I tightened them up and reinstalled the original driver and now it sounds like it's supposed to, bass and all. I am beginning to wonder if the bass dropping out probably was just a loose wire and not a crossover problem

 

"

The first three-way Klipschorn incorporated a Jensen RP203 tweeter. This tweeter came from the famous Jensen G-610 Triaxial 15" driver and required considerable negotiations with Jensen. It was not until mid-1952 that all Klipschorns were three-way. A two-way Klipschorn with response to 12Khz was generally adequate for program material up to that time. The University MID-T- 4401 replaced the Jensen unit as the tweeter of choice later in 1951.

"

[Marvel]

On 10/16/2019 at 4:13 PM, tinpan said:

I am beginning to wonder if the bass dropping out probably was just a loose wire and not a crossover problem

 

Quite possibly true. The first thing most people on here do is loosen and re-tighten all the connections. Unless a part is missing our quite obviously broken, it is a good this to listen to them a bit before starting to chase rabbits.

[MEH Synergy]

22 minutes ago, Marvel said:

it is a good this to listen to them a bit before starting to chase rabbits.

But they are so tasty... (good advice). 

[tinpan]

Well, that was the problem, these things sound amazing like they are supposed to now. Thank you for everyone's help

 

 

Here's a link to a video of them playing

[MEH Synergy]

39 minutes ago, tinpan said:

Well, that was the problem, these things sound amazing like they are supposed to now. Thank you for everyone's help

 

 

Here's a link to a video of them playing

Thanks for sharing. Video needs more background noise though.... You can almost hear the music 😂 (sorry couldn't help myself).   Congrats on getting them up and running!