Hey Ken,
Very interesting!
It seems that going for mostly PP is not the way to go.
Another idea is we could use a LL electrolytic and bypass it with a mylar film or PP capacitor. I have some mylar film capacitors I can try out, I can use 24uF LL Alcap with a 2.2uF mylar film (or, 4.4uF, I have several of these) in parallel. My IMFs are done this way (although, not with a LL electrolytic) and in comparing them to the lower model which does not use mylar film capacitors bypassed, it does improve the distortion and coloration. I will give this a shot tonight using the Elcaps and see if it helps the situation.
Going active is definitely enticing, isn't it? Remove the whole capacitor debate out of the question. This will certainly open the speakers up and allow you to hear more of the driver and a lot less of any crossover. I think, though, tri-amping or even bi-amping will make a considerable difference as well and I would at least start with that.
As for the bass yep, you are correct. The specs are very misleading "18Hz to beyond audibility". No, they do not produce bass that deep! 40Hz is where most music lies anyways, so going lower then that is not really necessary. The bass they have is well extended and makes the speaker sound full.
I'll post my results later tonight.
Oh, by the way, this may be of interest, a Stereo Review magazine review of the 66. It includes measurements so that is helpful.
https://drive.google.com/file/d/0B7hRRLs-gOwIYktrS0Z3cXRoLXM/view?usp=sharing
Very interesting!
It seems that going for mostly PP is not the way to go.
Another idea is we could use a LL electrolytic and bypass it with a mylar film or PP capacitor. I have some mylar film capacitors I can try out, I can use 24uF LL Alcap with a 2.2uF mylar film (or, 4.4uF, I have several of these) in parallel. My IMFs are done this way (although, not with a LL electrolytic) and in comparing them to the lower model which does not use mylar film capacitors bypassed, it does improve the distortion and coloration. I will give this a shot tonight using the Elcaps and see if it helps the situation.
Going active is definitely enticing, isn't it? Remove the whole capacitor debate out of the question. This will certainly open the speakers up and allow you to hear more of the driver and a lot less of any crossover. I think, though, tri-amping or even bi-amping will make a considerable difference as well and I would at least start with that.
As for the bass yep, you are correct. The specs are very misleading "18Hz to beyond audibility". No, they do not produce bass that deep! 40Hz is where most music lies anyways, so going lower then that is not really necessary. The bass they have is well extended and makes the speaker sound full.
I'll post my results later tonight.
Oh, by the way, this may be of interest, a Stereo Review magazine review of the 66. It includes measurements so that is helpful.
https://drive.google.com/file/d/0B7hRRLs-gOwIYktrS0Z3cXRoLXM/view?usp=sharing
OK so I tried the Mylar Film cap bypassed on the 24uF Elcap.
In doing some A/B testing, this seems to have made a positive improvement. The midrange becomes more compelling and lifts up the higher midrange giving it a less dark tone. I am going to put one in the other speaker and listen to them for a while and see how I like it. It was not a huge change, like going from the Solen to the LL Electrolytic, but rather a small improvement in areas I think that needed it. I'll report more when I've had a chance to listen to them in stereo like this, but I think I like the way it sounds.
In doing some A/B testing, this seems to have made a positive improvement. The midrange becomes more compelling and lifts up the higher midrange giving it a less dark tone. I am going to put one in the other speaker and listen to them for a while and see how I like it. It was not a huge change, like going from the Solen to the LL Electrolytic, but rather a small improvement in areas I think that needed it. I'll report more when I've had a chance to listen to them in stereo like this, but I think I like the way it sounds.
Well well, this has been an interesting change!
At first, I wasn't sure what I thought after putting in a film cap parallel onto the 24uF LL Elcap in the other speaker so both matched. I got this sense like the speaker sounded too relaxed and perhaps lost something.
However, upon more listening I am beginning to think this was a positive improvement overall. For the first time since I have listened to these, I was actually able to picture myself hearing the singer and instruments live. Before I could always hear coloration, something just not quite right with the timbre. With the mylar film capacitor, the sound has relaxed just a bit, but the tone is more accurate. The midrange has become richer and less dark in nature, and more open. I like what I am hearing.
It'll be interesting to see what happens with the Alcap caps and see if the combination is too much or more of a good thing. Hopefully those come in soon, but I'm not counting on them coming in before Christmas.
At first, I wasn't sure what I thought after putting in a film cap parallel onto the 24uF LL Elcap in the other speaker so both matched. I got this sense like the speaker sounded too relaxed and perhaps lost something.
However, upon more listening I am beginning to think this was a positive improvement overall. For the first time since I have listened to these, I was actually able to picture myself hearing the singer and instruments live. Before I could always hear coloration, something just not quite right with the timbre. With the mylar film capacitor, the sound has relaxed just a bit, but the tone is more accurate. The midrange has become richer and less dark in nature, and more open. I like what I am hearing.
It'll be interesting to see what happens with the Alcap caps and see if the combination is too much or more of a good thing. Hopefully those come in soon, but I'm not counting on them coming in before Christmas.
Hi Jeffrey
The maylar is doing much the same as what I have been experiencing mixing PP/LL Lytic. You have a mix of approx 8% Maylar.
I am now looking at trying one third PP and two thirds LL Lytic. It will be 10uf Ansar PP and 20uf LL Lytic made up of 10uf x2 so three caps in the bundle. The Lytics will be either Mundorf or Visaton.
I will also be doing a head to head on these two types of lytic on their own, made up of x2 15uf. I allready have the Mundorfs.
Like you mentioned x-mas is going to get in the way of things now.
The maylar is doing much the same as what I have been experiencing mixing PP/LL Lytic. You have a mix of approx 8% Maylar.
I am now looking at trying one third PP and two thirds LL Lytic. It will be 10uf Ansar PP and 20uf LL Lytic made up of 10uf x2 so three caps in the bundle. The Lytics will be either Mundorf or Visaton.
I will also be doing a head to head on these two types of lytic on their own, made up of x2 15uf. I allready have the Mundorfs.
Like you mentioned x-mas is going to get in the way of things now.
I found a pair 5uf Sonicaps and tried these with 25uf Alcap LL.
This was better.
I also had a pair of 4.7uf Jantzen Superior Z-Caps so I tried these with the 25uf Alcap LL. This was the best combination yet, just enough PP to give some richness and detail to the mids.
So about 5uf PP + 25uf LL Lytic seems to be about right, to my lug holes anyway.
Mmnnn, not ideal values for availability, so 8uf PP + 22uf LL Lytic.
This was better.
I also had a pair of 4.7uf Jantzen Superior Z-Caps so I tried these with the 25uf Alcap LL. This was the best combination yet, just enough PP to give some richness and detail to the mids.
So about 5uf PP + 25uf LL Lytic seems to be about right, to my lug holes anyway.
Mmnnn, not ideal values for availability, so 8uf PP + 22uf LL Lytic.
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Good stuff Ken.
It seems that a low value PP combined with the 24/25uF LL electrolytic is a good combination. I don't have any lower value mylar film caps to try, I would be interested to see what a 30uF LL cap bypassed with a very low value might do.
It sounds like we are closing in on a stellar combination of capacitors for the midrange circuit though which is excellent.
One thing I am going to try, for fun, is a NOS PIO russian capacitor bypassed on the LL electrolytic. This is counterintuitive to what we are trying so far but since I have some on hand, I want to see what happens.
Jeffrey
It seems that a low value PP combined with the 24/25uF LL electrolytic is a good combination. I don't have any lower value mylar film caps to try, I would be interested to see what a 30uF LL cap bypassed with a very low value might do.
It sounds like we are closing in on a stellar combination of capacitors for the midrange circuit though which is excellent.
One thing I am going to try, for fun, is a NOS PIO russian capacitor bypassed on the LL electrolytic. This is counterintuitive to what we are trying so far but since I have some on hand, I want to see what happens.
Jeffrey
All right, I now have both 24uF Elcap LLs bypassed with 0.33uF 500V K40 Russion PIO capacitors.
In my testing against the one speaker with the mylar film, the biggest change I could hear was that the midrange seemed warmer and richer. Kinda like my experience between my Sansui solid state equipment and the tube gear, it warms up and produces a more smooth, relaxing midrange that's easy to listen to. It's like "ahhh" just easy to relax into.
In replacing the mylar film in the other and listening in stereo, right off the bat I like this more than the mylar film caps. The thing about the film capacitors is while they were more natural and compelling, they lost a bit of the musicality edge that just the Elcap had. It was easier to prefer the original Elcaps, but at the same time not. This is why I struggled with it at first. Today when I fired it up again, I noted the same things, but as I listened I began to appreciate the qualities that the film caps brought.
However this time around, with the PIO caps bypassed, it was much easier to enjoy the sound. It wasn't a "I'm not sure if I like this", it was "Oh yes, this is nice!". I am starting to think of ditching the idea of making these a natural sounding speaker, and simply focusing on what they are already good at and just making it better. The PIO cap bypassed on the Elcap seems to have just done that - the midrange is warmer, but more soothing and satisfying. I'm very curious about how these would sound with the Alcaps.
Edit:
Put on some Norah Jones - oh yeah. This added warmth is welcome to a voice like this.
In my testing against the one speaker with the mylar film, the biggest change I could hear was that the midrange seemed warmer and richer. Kinda like my experience between my Sansui solid state equipment and the tube gear, it warms up and produces a more smooth, relaxing midrange that's easy to listen to. It's like "ahhh" just easy to relax into.
In replacing the mylar film in the other and listening in stereo, right off the bat I like this more than the mylar film caps. The thing about the film capacitors is while they were more natural and compelling, they lost a bit of the musicality edge that just the Elcap had. It was easier to prefer the original Elcaps, but at the same time not. This is why I struggled with it at first. Today when I fired it up again, I noted the same things, but as I listened I began to appreciate the qualities that the film caps brought.
However this time around, with the PIO caps bypassed, it was much easier to enjoy the sound. It wasn't a "I'm not sure if I like this", it was "Oh yes, this is nice!". I am starting to think of ditching the idea of making these a natural sounding speaker, and simply focusing on what they are already good at and just making it better. The PIO cap bypassed on the Elcap seems to have just done that - the midrange is warmer, but more soothing and satisfying. I'm very curious about how these would sound with the Alcaps.
Edit:
Put on some Norah Jones - oh yeah. This added warmth is welcome to a voice like this.
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After some more listening, I am convinced this is definitely the best these 66s have sounded. The midrange snapped into focus, and it has this sweet, almost lucid like quality to it. You can hear the nuances in instruments much easier and everything is just nice.
If you have access to some, I recommend giving it a try, you may like it Ken.
If you have access to some, I recommend giving it a try, you may like it Ken.
I won't be using any combination with old Elcaps in the mix. One of the key factors in me doing all this is to replace the old stuff which could fail at any time and possibly take out my drivers.
I only go back to them as a reference point when voicing with new stuff.
The Elcaps sound pretty good on their own so I can imagine the type of result you are getting.
I won a 6 channel Amp last night on eBay so I'm trying to organise a courier for that today.
I only go back to them as a reference point when voicing with new stuff.
The Elcaps sound pretty good on their own so I can imagine the type of result you are getting.
I won a 6 channel Amp last night on eBay so I'm trying to organise a courier for that today.
No sign of the Alcaps yet, however there is still two days to go where they could arrive.
I am definitely convinced that the PIOs are doing good things for the midrange. Much more compelling and vivid than just the electrolytic.
I also went ahead and installed some spikes on the 66s. Again, another improvement, the low end is cleaner and the speaker sounds more alive. The 66s also look great on spikes!
I am definitely convinced that the PIOs are doing good things for the midrange. Much more compelling and vivid than just the electrolytic.
I also went ahead and installed some spikes on the 66s. Again, another improvement, the low end is cleaner and the speaker sounds more alive. The 66s also look great on spikes!
Yes, I also found spikes clean up the bottom end.
The concrete plinths I made have adjustable spikes. Each one weighs 23Kg and the speaker bases each have three "Soundcare" feet screwed in. These are like spikes that carry round their own seat/cup and they adjust to the angle of the surface they are sat on. The speakers just sit on the plinths and this combination works very well.
The concrete plinths I made have adjustable spikes. Each one weighs 23Kg and the speaker bases each have three "Soundcare" feet screwed in. These are like spikes that carry round their own seat/cup and they adjust to the angle of the surface they are sat on. The speakers just sit on the plinths and this combination works very well.
That looks great, Ken. I remember seeing the pictures over at The Art of Sound and was impressed by how factory you made them look. The Celestion logos are a nice touch 
Well, still no sign of the Alcaps but I am really happy with how these sound. Like I mentioned these are not very accurate sounding or compelling, but they have a lovely vintage sound that is enjoyable to listen to. I have mine hooked up to a Sansui AU-555a and it sounds great. I still think the Alcaps will be better than the Elcaps in there now, but I'm certainly not complaining with how they sound right now. The PIO took the midrange to a new level that I wasn't expecting.
The only thing I'd really like to do is fashion new grills for them, because I prefer the look of a speaker with the grill on. Although I have the originals on, I do find it muddies up the midrange just a touch. I think new grills without the metal mesh these have with new grill cloth material will do the trick, but I'm not there yet.
Ken have you done any listening to yours with the grills on versus off? If so what did you find?
Well, still no sign of the Alcaps but I am really happy with how these sound. Like I mentioned these are not very accurate sounding or compelling, but they have a lovely vintage sound that is enjoyable to listen to. I have mine hooked up to a Sansui AU-555a and it sounds great. I still think the Alcaps will be better than the Elcaps in there now, but I'm certainly not complaining with how they sound right now. The PIO took the midrange to a new level that I wasn't expecting.
The only thing I'd really like to do is fashion new grills for them, because I prefer the look of a speaker with the grill on. Although I have the originals on, I do find it muddies up the midrange just a touch. I think new grills without the metal mesh these have with new grill cloth material will do the trick, but I'm not there yet.
Ken have you done any listening to yours with the grills on versus off? If so what did you find?
Hi Jeffrey
The factory look was what I was trying to achieve with the plinth and label for the binding posts, so thanks for that.
Grills on/off - I prefere grills on, both sonically and visually. I don't like seeing drivers pumping, I find it distracting. Most speakers were voiced with grills on, they usually sound different with them off, but not necessarily better, this is a matter of individual taste though. Tweeters often sound too forward with grills off.
My six channel Rotel amp arived today and I am listening to the 66's through it now in tri-amped configuration. I have taken the L-Pads off the mid and tweeter and I'm using the attenuation pots on the amp channels to get the levels right.
The amp is the RMB-1066 model and was aimed at multi room or AV use so not exactly HiFi. However, the speakers are sounding a lot cleaner through it, the tweeter has lost all signs of distortion and the mid distortion has reduced substantially. This confirms that whatever is causing it, the fault lies in the band pass midrange filter. When I get the parts on the new boards with wider spacing of the coils this may have a further effect on the distortion.
I can't order any Visiton caps till after xmas and possibly not till the New Year for the Ansar PP's. I am well down the road to sorting an analogue active crossover, I've done a layout and sourced parts/prices if you check my website you will see the layout in my 66 project, which uses ready made opamp modules. You can knock together a basic 3-way (x2) without a case for £100 including PSU and Tranny.
The factory look was what I was trying to achieve with the plinth and label for the binding posts, so thanks for that.
Grills on/off - I prefere grills on, both sonically and visually. I don't like seeing drivers pumping, I find it distracting. Most speakers were voiced with grills on, they usually sound different with them off, but not necessarily better, this is a matter of individual taste though. Tweeters often sound too forward with grills off.
My six channel Rotel amp arived today and I am listening to the 66's through it now in tri-amped configuration. I have taken the L-Pads off the mid and tweeter and I'm using the attenuation pots on the amp channels to get the levels right.
The amp is the RMB-1066 model and was aimed at multi room or AV use so not exactly HiFi. However, the speakers are sounding a lot cleaner through it, the tweeter has lost all signs of distortion and the mid distortion has reduced substantially. This confirms that whatever is causing it, the fault lies in the band pass midrange filter. When I get the parts on the new boards with wider spacing of the coils this may have a further effect on the distortion.
I can't order any Visiton caps till after xmas and possibly not till the New Year for the Ansar PP's. I am well down the road to sorting an analogue active crossover, I've done a layout and sourced parts/prices if you check my website you will see the layout in my 66 project, which uses ready made opamp modules. You can knock together a basic 3-way (x2) without a case for £100 including PSU and Tranny.
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Good stuff Ken, glad to hear the Rotel is working out for you. I've ran active setups before and done bi-amping and always found it made an improvement. I think that because you are using an amplifier that is amplifying all 6 channels the same that should improve phasing characteristics which I think is a smart way to go.
As for the grills I think I'm going to leave mine on. You make a good point that these may have been voiced with the grills on - looking at the cabinets, there is a hole on the bottom to hold the grill in place so they expected you to keep the grill on. They sound good and I like the way they look this way so I think I'll leave it.
Oh another question, Ken, have you devised any method for replacing the foam on the sides? I'm going to look into some foam strips that would work there. I imagine this will be helpful for the sound as well.
As for the grills I think I'm going to leave mine on. You make a good point that these may have been voiced with the grills on - looking at the cabinets, there is a hole on the bottom to hold the grill in place so they expected you to keep the grill on. They sound good and I like the way they look this way so I think I'll leave it.
Oh another question, Ken, have you devised any method for replacing the foam on the sides? I'm going to look into some foam strips that would work there. I imagine this will be helpful for the sound as well.
Hi Jeffrey
Not had any vibration problems without the foam strips in place so never bothered.
You could use self adhesive foam tape or the furry part off velcro fastening. Both available in Black and in various widths, but like I say, it's never been a problem, perhaps I haven't been playing loud enough.
The second hand Rotel amp is just a cheap way of trying tri-amping or going active. If I end up going that route permanently I will build a 6 channel amp for the job. The abuility to adjust the gain pots on the front panel is great, mids too forward, just turn em down a touch, soo easy to adjust the voicing.
Not had any vibration problems without the foam strips in place so never bothered.
You could use self adhesive foam tape or the furry part off velcro fastening. Both available in Black and in various widths, but like I say, it's never been a problem, perhaps I haven't been playing loud enough
.The second hand Rotel amp is just a cheap way of trying tri-amping or going active. If I end up going that route permanently I will build a 6 channel amp for the job. The abuility to adjust the gain pots on the front panel is great, mids too forward, just turn em down a touch, soo easy to adjust the voicing.
This is the Amp I purchased second hand.
It's a Rotel RMB-1066, I wouldn't call it HiFi more like MidFi, but it’s a cheap way into Tri-Amping or Active crossovers. This model was mainly sold for home cinema use, where folks wanted to get into separates and split the amplification from the receiver/control section. It has several features that make it attractive for multi channel music use though.
First it is set up as 3 pairs of channels, so it's like having 3 Stereo Power Amps in one box.
Second, each pair has it's own gain control, the pots are adjusted using a screwdriver and are located between the front fins, as indicated on the picture. For three way speakers this allows adjustment of each driver pair from one pot, so left and right bass drivers can be adjusted together as an example. Once drivers are initially matched for sensitivity the volume is controlled from your pre-amp.
Third is the RCA inputs, one pair of inputs for each pair of channels, again more like a stereo amp x3 which is good for going Active.
Lastly the input pairs can be linked by sliding a couple of switches so that one pair of inputs serves all three amp sections, saving on cable runs etc and useful for Tri-Amping from a single pair of outputs on a Pre-Amp.
This is a very versatile piece of kit, you can also bridge any pair of channels to increase the power in that section but reducing it to single channel. So you can have 6,5,4,or 3 channel output depending on which pairs you bridge. Power output is 60W/8 Ohm x6 or 150w/8 Ohm x3 (Bridged).
The Visaton Low Loss bi polar electrolytics arrived a few days back and I’ve been doing some comparisons for the 30uf Series cap using purley LL Lytics. (15+15uf)
I have listened to and my order of preference is:
1). Visaton
2). Mundorf
3). Alcap
To me, the Visaton and Mundorf are better on all counts than the Alcaps, period.
With my first and second choices the decision is less cut and dry and as with a lot of this type of comparison, my favourite changed from track to track, so it will depend on what voicing you prefer. I will try and describe the difference which is subtle and not dramatic:
Compared to the Visaton, the Mundorf is a touch warmer/softer sounding, so gives good timber to acoustic guitar body for example. It’s not quite as crisp being a little less transparent, less dynamic with not quite the same punch. This makes trumpet sound less convincing for instance. Voices however are slightly smoother and less prone to highlight the resonance.
Both these caps are good, I came down on the side of the Visaton for being more realistic with some instruments, it’s slightly more transparent and just conveys a little more energy and emotion, but it is a small difference.
Next is to try a mix of the Visaton and Polyprop............
I have listened to and my order of preference is:
1). Visaton
2). Mundorf
3). Alcap
To me, the Visaton and Mundorf are better on all counts than the Alcaps, period.
With my first and second choices the decision is less cut and dry and as with a lot of this type of comparison, my favourite changed from track to track, so it will depend on what voicing you prefer. I will try and describe the difference which is subtle and not dramatic:
Compared to the Visaton, the Mundorf is a touch warmer/softer sounding, so gives good timber to acoustic guitar body for example. It’s not quite as crisp being a little less transparent, less dynamic with not quite the same punch. This makes trumpet sound less convincing for instance. Voices however are slightly smoother and less prone to highlight the resonance.
Both these caps are good, I came down on the side of the Visaton for being more realistic with some instruments, it’s slightly more transparent and just conveys a little more energy and emotion, but it is a small difference.
Next is to try a mix of the Visaton and Polyprop............
Visaton caps are very good both electrl and foil type . mixing them with clarity caps or high performance jantzen caps makes them really good sounding choice. Best balance i got was using ratio in 95&5 % proportion electro&foil or polys. Good luck and thx for informing about your findings. Happy new year
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