Request for Advice on Upgrading Spendor Crossovers

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Jeff

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Re: Request for Advice on Upgrading Spendor Crossovers
« Reply #20 on: 2 Feb 2018, 09:06 pm »
Roger that.  Any "correct" schematic is a thing of beauty to me :thumb:  Could you email me (at cs) your schemo?  My neck is starting to get a crick...  BTW, copy and paste that PM because I did not get it.

HAL

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Re: Request for Advice on Upgrading Spendor Crossovers
« Reply #21 on: 2 Feb 2018, 09:08 pm »
You should check the woofer schematic.  The way it is drawn, the inductor is shorted out.

Possibly a break in the circuit between the 3rd and 4th caps. 

Jeff

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Re: Request for Advice on Upgrading Spendor Crossovers
« Reply #22 on: 2 Feb 2018, 09:14 pm »
You should check the woofer schematic.  The way it is drawn, the inductor is shorted out.

Possibly a break in the circuit between the 3rd and 4th caps.

It looks fine to me.  Look closer HAL...   :lol:  I always wanted to say that :oops:

Jeff

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Re: Request for Advice on Upgrading Spendor Crossovers
« Reply #23 on: 2 Feb 2018, 09:19 pm »
The inductor connections are misleading, but I'm not have trouble with it.  And, more than one might be a transformer.

atkinsonrr

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Re: Request for Advice on Upgrading Spendor Crossovers
« Reply #24 on: 2 Feb 2018, 09:54 pm »
Hal-- Probably just my sloppy pencil work.  I think the Woofer circuit is OK, just a bunch of caps in parallel and then an inductor in parallel to it all. 

Jeff-- Wow...transformers! I never considered...   Yeah, I was surprised to see the three leads.  So that explains it!   Two of em with three leads: one in the Tweeter and one in the MidRange.   Will get the schematic and PM resent to you right now. 

atkinsonrr

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Re: Request for Advice on Upgrading Spendor Crossovers
« Reply #25 on: 2 Feb 2018, 09:59 pm »
 :duh:  Yeah I see what you mean.  Inductor on woofer should of course be shown parallel, between + and - legs. 

HAL

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Re: Request for Advice on Upgrading Spendor Crossovers
« Reply #26 on: 2 Feb 2018, 10:10 pm »
Yeah, if you load that much capacitance on an amp's output stage might go boom. 

Probably a second order L-C filter, series L and parallel C to the woofer. 

atkinsonrr

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Re: Request for Advice on Upgrading Spendor Crossovers
« Reply #27 on: 2 Feb 2018, 10:25 pm »
Hal-- Let me confuse us all further.  :lol:

Ignore my last post.  I traced the LF section more carefully.  It looks like that Inductor is in series on the positive leg.  So the first thing the amp sees coming into the speaker on the + leg is the Inductor, after the inductor it encounters that 70uf capacitance and then heads out to the woofer.  I should have shown a break between the first cap and the + binding post. 

Is that making more sense?  Or am I still violating the laws of physics?  Are we still going BOOM?

HAL

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Re: Request for Advice on Upgrading Spendor Crossovers
« Reply #28 on: 2 Feb 2018, 10:29 pm »
Yep, that sounds good.

Jeff

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Re: Request for Advice on Upgrading Spendor Crossovers
« Reply #29 on: 2 Feb 2018, 11:41 pm »
I should have shown a break between the first cap and the + binding post.

It always looked fine to me.  Mainly because there always appeared to be a break.  I assumed you meant it to be there :dunno:  I'll have two recommendations tonight, but they will be limited by the fact that I know little about the inductor/trannys.

EDIT: Rob is going to send me the inductor/trannys, so I will delay my recommendations pending that evaluation.
« Last Edit: 3 Feb 2018, 08:20 am by Jeff »

atkinsonrr

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Re: Request for Advice on Upgrading Spendor Crossovers
« Reply #30 on: 17 Feb 2018, 12:25 am »
I spoke to Jeff and I understood he was going to update this thread, but I see its not updated, so maybe I misunderstood.  I decided not to send my crossover to Jeff as there was some confusion about the proper phasing of the individual drivers.  I had had the drivers hooked up with the tweeter out of phase with the rest of the drivers.  But, as I had the back off the one speaker I tried it with the alternative, i.e. with midrange out of phase. My intitial impression that I reported to Jeff was that it sounded more forward and less veiled.  There is much to love about the sound quality of the Spendors and I would like to keep changes to a "tweak" and not attempt a wholesale change.  I told Jeff I would try it with the one speaker with the midrange out of phase for awhile to check my long term perceptions.  I have since gotten confirmation (from folks on the Classic Spendor Yahoo Group) that the correct factory wiring has the tweeter out of phase. So I will rewire back to that.  Jeff helped me determine that the current resistors are magnetic, and per his recommendation I have received from him Mills resistors to upgrade the two resistors in the crossover.  I also received from Jeff Mundorf Supreme caps to upgrade the last cap before the drivers in both the midrange and tweeter circuits.  And, I have on-hand Solen caps of the correct value to replace the two 20uf electrolytics in parallel with each woofer.  Jeff suggested to me that tube driven speakers with large woofers (mine are 13") benefit from bi-wiring.  So I also now have on hand Duelund 12GA and 16GA wire to biwire the bass and mid/tweeter sections respectively of each speaker. My intent is to go slowly with these four changes, try one change at a time, give myself time to acclimate and then decide if its a positive or negative change.  I will report back on my findings over the next several weeks.   Thanks -- Rob

Jeff

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Re: Request for Advice on Upgrading Spendor Crossovers
« Reply #31 on: 17 Feb 2018, 03:50 am »
Apparently, there was some sort of miscommunication.  I assumed you had found your problem, and did not need any further help for the time being.  "If it ain't broke, don't ....."

I had nothing to report after your finding.  I assumed you would report your finding if you chose to.  As for my initial observation that the magnetic BP hardware, resistor end caps, and cored inductors hurt dynamics, detail and transparency, I stand behind that.  However, I assumed you no longer had an issue with these things.  As a matter of fact, I even suggested not changing anything until you figured out the wiring, and took a few month to get to know the speakers again.

In any event, I think we can agree that the narrative has changed from "advice on upgrading Spendor crossovers" to "my observations of incorrectly wired Spendors"  :D :icon_lol:

atkinsonrr

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Multiple post
« Reply #32 on: 29 Mar 2018, 05:19 pm »
Multiple post

atkinsonrr

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Re: Request for Advice on Upgrading Spendor Crossovers
« Reply #33 on: 29 Mar 2018, 05:32 pm »

After listening for a few weeks to the speakers with what I verified was correct wiring, I began changing the crossover to one speaker as mentioned above, and I got it completely built out yesterday. 

So others can follow along, here is the corrected schematic. BTW those boxes marked "XFMR" on the schematic should be marked as inductors.  When I drew the schematic I was in contact with Jeff and he surmised they might be transformers as they had three connections, not two as you would normally find with an inductor. I think this is one reason he wanted me to send the board back to him, so he could take a look at these strange things.  Since then, I was able to confirm with Spendor that they spec or manufacture their own proprietary multi-tap inductors for use in their crossovers.  So I am pretty sure that's what they are. :



These are the final changes I made:
Woofer: Those two 20uF electros are now one Solen 43uF film with a 5 ohm Dale resistor in series.
Midrange: The 10uF and 6.8uF caps are now replaced with one 18uF Clarity CSA series; both resistors replaced with Mills MRA 12W; the 4.7uF and 1.5uF are replaced with one Mundorf Supreme 6.8uF.
Tweeter: The 1.5uF is replaced with a Clarity ESA series; the .33uF is replaced with a .5uF Russian MBM PIO cap; the 6.8uF is replaced with  a Mundorf Supreme 6.8uF.    All caps were burned in on a cooker for 3-4 weeks before I started.

Upon first listening, the sound was completely disjointed and the upgraded speaker was so different than the stock one there was no stereo image at all!  I was about to take the board totally back to stock.  But then thought it might be the crossover circuit needed the ESR of the electrolytics (I couldn’t understand why Spendor left 2 electros in when everything else on the board is film and the electros are only 20uF, a value that could easily be handled by a film cap.)  Still, could this be affecting the entire sound of the speaker?  The only other difference from stock values was, at that point, I had pulled that .33uF cap in the tweeter but not replaced it with anything.  Couldn’t understand how this would make much difference either. 

So fully thinking I would go back to stock, but curious about the ESR issue, I put a 5 ohm Dale wirewound I had on hand in series with the 43uF Solen in the woofer section and also while I was there, put in a .5uF cap in the tweeter section.  Also, sensing the 20GA stranded I used for cap leads might be affecting things, so I went to 14GA solid copper.

I hooked it all back up not expecting much, started playing music and immediately knew it was behaving much like the other stock speaker because I had a stereo image and a soundstage again.  Checking closer, tonality was essentially the same.  I am blown away. How could this be fixed by adding 5 ohms and .5uF?  Not disjointed at all now.  Same Spendor essence as the other untouched stock speaker, but simply clearer.  In comparison the stock speaker has a ‘tizzy’ distortion that overrides everything and it also sounds congested.  Always was aware of that congestion (its even pointed to in reviews of the speaker) but I had feared that the congestion was part and parcel to the tonal quality, and if I got rid of that, I got rid of the "Spendor sound".  But not true!  Could never go back to stock now as it seems so clearly distorted. 

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Jeff

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Re: Request for Advice on Upgrading Spendor Crossovers
« Reply #34 on: 5 Apr 2018, 05:58 am »
That is some fantastic combo  :o  If it turned out to be an improvement, it is likely more to do with chance.  However, if your ears are telling you  :thumb: you have some level of success  :D

The reason I requested the board/inductors was to measure their values and DCRs.  And, to see if any were transformers, or multi-tap...  Your original laundry list of desired improvements potentially depended on some of these inductors.  Once you found out you had wiring issues, and...  I figured that was the end of it.

atkinsonrr

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Re: Request for Advice on Upgrading Spendor Crossovers
« Reply #35 on: 5 Apr 2018, 05:59 pm »
Hey Jeff. 

Didnt see any interest in this thread so didnt bother to update. But you're right, it was a 'fantastic' combo.  And it did sound good (hell, it sounded so good at one point my wife and I were dancing to Jimi Hendrix  :scratch:)  But alas, once I pulled the other crossover to bring it in line with the modded one I noticed I'd managed to switch the positions of the 22R and 33R resistors in the midrange circuit!  :duh:  Even though it was sounding good, that was a little TOO fantastic, so back to square one. 

Leaving the unmodded speaker alone, went back to the modded one, switched resistors to their correct postions and... too bright, particularly on female vocals, right near the 4K mid to tweeter crossover point.  No longer content to take it back to stock after the earlier glimpse of what the new caps could bring, I decided to keep at it. After researching effects of differing R and C values in crossovers, I realized the added C I put in series with the tweeter was taking it in the wrong direction. Changed it to a .1uf to attempt a shallower slope at the bottom of its passband. Still too bright, so added a Dale 2R I had on hand in series at the amp end of the tweeter crossover circuit to bring the level down.  And, after some A-Bing determined the 5R I had in series with the woofer cap was not needed and removed it. 

Sounding good again.  Now the only changes from stock are:

1. An added 2R in series with tweeter
2. A decrease in the one cap on tweeter from .33 to .1uf (for total series C of .09 vs .27uf)
3. Replacement of the 1.5 and 4.7uf (6.2uf total) in parallel with midrange with a single 6.8uf
4. Replacement of the 10 and 6.8uf (16.8uf total) in parallel with midrange with a single 18uf

I have hopes that as everything burns in, I might be able take changes 1 and 2 back to stock.

Jeff: Would you agree that changes 3 and 4  (7% greater C and 9% greater C) are close enough to stock so they're not changing the sound appreciably?  Still matching the designer's intent?  Should I be concerned with trying to match these values closer to the stock ones?

Thanks for your input.