WE 755a vs PIM-8 in Bae Silbatone boxes

[jeb98]

(Long post sorry…)

So, I found an old zinc finish Western Electric 755a in one of those KS-12046 small cabinets. Came from a guy who worked in an old phone company building and over the course of a number of years he found 3 of these cabinets filled with the early zinc WE 755a. All were found individually so he sold them off one at a time. No pairs.. and I only have this one.

I’ve owned three Altec 755a before and one WE 755a before but sold them all. I built the Stefano Bae Silbatone cabs for the Altec 755a but couldn’t get enough bass for my liking. First off, I get a bit more bass out of this one. I will eventually play around with finding a sub that would work with this (if I somehow find a 2nd to make a pair). The WE 755a have less of the damping coating on the surrounds than the Altec 755a and I feel it allows a bit more bass response. This one is still very supple surround coating, a very nice performer!

I also happen to have one single Pioneer PIM-8 (Lafayette SK-98) So I decided to put them both in the Bae cabs and do some comparisons.

First impressions, the 755a is more efficient or plays a bit louder. Listening tests done in mono adjusting volume to match between the two speakers. The 755a has more high frequency range. Cymbals shimmer and are more bright with more air on top. The 755a has better off axis performance (70 degrees coverage angle according to Western Electrric literature) while the PIM-8 is more directional seems to have worse off axis performance. The 755a seems to have a bit more bass and a bit more focused bass in these cabs (still missing some lower octaves of course). The midrange seems to be more spacious with more clarity between instruments or singers. This is something I’ve found with Western Electric equipment like the 728B. Kind of the way a SET amp will have that midrange spacious effect where instruments seem a bit more clearly defined in their space compared to a Push Pull tube amp, if that makes sense. While the PIM-8 had a thicker more focused midrange sound, less smooth than the 755a in the midrange but the PIM-8 still had a nice fleshed out midrange sound. Tenor sax for instance sounded nice and full and lush, and maybe a bit thinner with the 755a.

I sold off my better tube preamp and power amps and turntables so I don’t have anything too exotic to test these with. First I tested with my refurbished Eico HF-81. My immediate reaction was the 755a was preferred. But, then I adjusted the treble knob on the HF-81 to boost the treble of the PIM-8 and they sounded much more similar to eachother. I found myself going back and forth many times nitpicking for minor differences and there were differences of course with the 755a having more of that “SET amp effect” on the midrange. But, it was difficult to decide which I truly preferred or which was “better”.

I like bespoke vintage things that were engineered with the methodical precision of Western Electric stuff and the history of it all so of course I prefer the 755a with my heart. And overall, with the better off axis performance, no need to add tone controls to boost treble, the 755a would be the better performance in a stereo pair. I prefer more minimalist preamps with no tone controls getting in the way. But the PIM-8 has a similar enough sound especially if you can boost the treble with your preamp section.

But, it’s still that 8 inch single driver sound. People say that the 755a has a sound like a western electric horn system and to me somehow it does; maybe that wide coverage angle and it’s dynamics and detail give it that sound, but it won’t replace a large scale horn system. I still really want to try it out in an Altec 618 cabinet so if any has any for sale let me know! Also looking to somehow find a second 755a 😢

I’ll keep messing around with these trying some different amps I have laying around. I’m actually listening to the in a stereo and get a pretty decent center image when getting the volume balanced and it sounds pretty nice actually….not ideal.

Anyway, thanks for reading if you made it this far.

Jonas

 

[je2a3]

I’ve owned three Altec 755a before and one WE 755a before but sold them all. I built the Stefano Bae Silbatone cabs for the Altec 755a but couldn’t get enough bass for my liking. First off, I get a bit more bass out of this one. I will eventually play around with finding a sub that would work with this (if I somehow find a 2nd to make a pair). The WE 755a have less of the damping coating on the surrounds than the Altec 755a and I feel it allows a bit more bass response. This one is still very supple surround coating, a very nice performer!

Back in the mid 90s I had a chance to compare the WE vs. Altec 755A in my open baffles. If memory is serving me right, the WE version just removed a smidgen of veil in the mids but overall frequency response and tonal balance was very similar. Back then the WE755As were breaching $1000/pr. and couldn't afford them.

I also happen to have one single Pioneer PIM-8 (Lafayette SK-98) So I decided to put them both in the Bae cabs and do some comparisons.

First impressions, the 755a is more efficient or plays a bit louder. Listening tests done in mono adjusting volume to match between the two speakers. The 755a has more high frequency range. Cymbals shimmer and are more bright with more air on top. The 755a has better off axis performance (70 degrees coverage angle according to Western Electrric literature) while the PIM-8 is more directional seems to have worse off axis performance.

I agree! The PIM-8/16/SK98 does beam which is probably why in some vintage applications of this driver, it was equipped with a super tweeter.

The 755a seems to have a bit more bass and a bit more focused bass in these cabs (still missing some lower octaves of course).

IME, although the PIM-8/16/SK98 works in the Silbatone cabinet, it works better in a bigger cabinet like the 618. Perhaps even better in the Pioneer spec'd cabinet, but I've never heard this.

The midrange seems to be more spacious with more clarity between instruments or singers. This is something I’ve found with Western Electric equipment like the 728B. Kind of the way a SET amp will have that midrange spacious effect where instruments seem a bit more clearly defined in their space compared to a Push Pull tube amp, if that makes sense. While the PIM-8 had a thicker more focused midrange sound, less smooth than the 755a in the midrange but the PIM-8 still had a nice fleshed out midrange sound. Tenor sax for instance sounded nice and full and lush, and maybe a bit thinner with the 755a.

As good as they are, I always thought the PIM-8/SK98 is more on the level of a 755C or E rather than the 755A.

But, it’s still that 8 inch single driver sound. People say that the 755a has a sound like a western electric horn system and to me somehow it does; maybe that wide coverage angle and it’s dynamics and detail give it that sound, but it won’t replace a large scale horn system.

I used the 755A as my reference for midrange accuracy and coherence which was why I was never satisfied with my Altec 2-way project until I landed a pair of 32C horns.

I still really want to try it out in an Altec 618 cabinet so if any has any for sale let me know!

IME, the 618 cabinet loaded with any of the 755s or PIM8/16/SK98 always exhibit an upper bass bloom when driven by my DIY SET amps. This is only ameliorated when I use my dynakit ST35 or JLH 1969 clone at the expense of the SET midrange magic. OTOH, the ST35/JLH 1969 driving 755s or PIM8 in the Silbatone cabinet, I get subjectively less bass and leaner overall sound. With SET amps I hear a much better tonal balance across the frequency range. I think damping factor is at play here.

Also looking to somehow find a second 755a 😢

I wish you all the best!😊

Anyway, thanks for reading if you made it this far.

Jonas

Great post!👍

 

[jeb98]

Thanks for the reply! Speaking of the 32 horn, here's a 755a to 753C comparison on youtube of a guy switching between a 755a and 753C. Go to 2:18 and he switches briefly from the 753C to a WE 755a. I've learned that no accuracy can really be taken from video clips of speakers but somehow this captures the sound of what it's like to switch to a larger scale horn system to a 755a. The 755a has a cool sound but it's missing some weight and depth to it's lower end for sure. www.youtube.com/watch?v=DGmvf7hjU3o&list=LL&index=1&t=144s

Perhaps I would like the upper bass bloom of the 618 cabinets. I may try to make a pair being close to the originals but first I'd need a second 755a and also I want to be sure it's worth going down that rabbit hole. When I had my 757a reproductions they really did trounce the 755a in midrange/overall clarity and smoothness, which does say a lot. Cannot recommend the Lycan 12027 horns made by our own Trieu enough. Those things are amazing.

Anyway. thanks again for the reply. I have clips of the speakers but I'm not sure I'll post them as they don't give such an accurate representation of what I'm hearing.

Best,

Jonas

 

[mhardy6647]

@jeb98 - I know I owe you a reply to your PM. I haven't forgotten!

 

[electrovice]

The Hamlins company in Seattle made a small speaker called "The Spacemaster" that used either the Hamlins "Black Box" variant of the Pioneer PIM 8 or the PIM 6. The Hamlins enclosure was about the same size as the Silbatone enclosure. Havenite Dan Quick had a pair for sale on the forum a few years ago. Link:

FS - Lafayette SK-98/Pioneer PIM-8 Speakers

I have a pair of Lafayette SK-98/Pioneer PIM-8’s in Hamlin cabinets. Excellent drivers. I’m selling because I finally got a pair of Altec 755A’s. Now the Altec’s cost me 10 times more than these, are they 10 times better, no. Are they 5 times better- no. Super efficient and dynamic! Drove with...

hifihaven.org

 

[paul300b]

I always wondered how the Goodmans Axiette 8” compared to these speakers. Anyone compared them?

 

[hifitown]

I just wanted to drop in and say that this was a great discussion. Jeb98, I'm pretty sure I generally agree with your assessment of the 755's strengths in clarity. They don't go low and they don't go super high. There are other high-performing full-range 8-inch drivers that can reach higher and lower frequencies. Some are truly exceptional. I've always appreciated the quality of 50's Matshushita PiM series in general, in all variations (as well as other stuff like Coral and early Fostex). However, we (generally) never really heard anything that could compete with top-tier 4.5-5 "star" speakers, according to our old rating system.

Someone else asked about the Goodmans Axiette (spelling might be off). It's sometimes a somewhat better speaker (they did not look it, but even the ceramic version was good) , if I recall correctly. But I generally prefer other European products. There are also some fantastic all-paper 8-inch cones with whizzers (Jensen, GE, even Quam, Magnavox, Zenith, Oxford, all sorts of stuff) that you can find. Additionally, there's some interesting high-gauss British equipment, such as Bakers and at least one model of Whitely Stentorian, among other items. It's always exciting to find them when you can.

There are some highly detailed full-range Jensens available, and other similar products, but they don't quite achieve the separation and resolution of others. However, Jeb98, you make a good point that with EQ adjustments, proper on-axis positioning, and other tweaks, you can get surprisingly close to WeCo quality, sometimes.

I know my opinions can be controversial, but if you ask me, open baffle is the way to go if conditions allow. Most cabinets are either too stuffy or resonant, although there are tricks to mitigate this. There are a few flat cabinets that don't interfere with the tone, but they don't add anything either, which is the best possible outcome.

The 618 box is quite useful, but it does have that woody boom that JE mentions. It's pleasant and has slightly more bass, old-school style, so you might really enjoy it with the right amplifier. It's basically the WE spec box, with a bit of extra volume added, as far as I remember. Walt used to build them (and bigger versions) back in the da, before he went to the Airwave cabinet. Simple is good in this case.

The woody-warm bass is due to a couple of factors: Altec didn't use much bracing, and they used very thin plywood. I'm not kidding; it's much thinner than what most people would build with today. It actually contributes to the pleasant sound of the cabinet, but it's not flat. I recently sold an original set to a local customer. There was minimal bracing and usually no insulation. Altec used 50's Douglas Fir Pine or some kind of heart pine in the laminates. It's just plywood, but it's very old and has the right sound for audio. I've recently started building 8-inch cabinets out of solid white and yellow heart pine and have achieved similar results.

I've spoken with projectorcollector on a few occasions about his reproductions. I think I convinced him to use flooring-grade pine plywood instead of birch to improve the authenticity. However, I believe costs were mounting on his end, so I'm not sure if he's still doing it. The cabinet is relatively simple to build, so I would focus more on materials than on skill. It would be interesting to emulate Altec's curious and inexpensive build quality to replicate the sound. Fortunately, the glass-reinforced hammertone paint finish is still available, if anyone is interested. However, I would probably opt for natural shellac.

Just like with open baffle, you get better performance from the 755 if you run the 618 cabinet with the cabinet leaning off of it a bit. This reduces bass but improves the midrange.
One other thing worth mentioning is that your observations about the bass response of the 755A unit-to-unit is absolutely correct, as I have handled many over the years. Sometimes the differences are due to voice coil alignment or dirt in the gap, but other times there's just a variance in factors like cone compliance. They all sound a bit different, so it's best to match them up and sell them in pairs, like I used to do and still sometimes can.

These days, I prefer to pull T/S parameters on them, as the differences become apparent, and I like to align them as closely as possible. The bench Fs of a 755 is not that low – most of them run around 95-105 Hz, give or take. Nowadays, there are 8-inch full-range speakers that can go as low as an old 15-inch woofer (40-50 Hz), albeit with serious trade-offs.

Lastly, I wanted to give further credence to the counterintuitive practice of comparing speakers/transducers via YouTube videos. As long as the recording is done with a good microphone and you have a pair of headphones or monitor speakers you trust (I recommend Yamaha NS-10s for that, which is another controversy), things stay "relative" and you can actually compare the tonality and quality of speakers, at least to some extent. I do it all the time, and when I get the real thing in front of me, I can't say I've ever really been led astray significantly. After all, this approach isn't much different than what a mix-down engineer or mastering engineer would do in a studio – listening to a "recording of a recording" on a known monitor, etc.

 

[RPMac]

I just wanted to drop in and say that this was a great discussion. Jeb98, I'm pretty sure I generally agree with your assessment of the 755's strengths in clarity. They don't go low and they don't go super high. There are other high-performing full-range 8-inch drivers that can reach higher and lower frequencies. Some are truly exceptional. I've always appreciated the quality of 50's Matshushita PiM series in general, in all variations (as well as other stuff like Coral and early Fostex). However, we (generally) never really heard anything that could compete with top-tier 4.5-5 "star" speakers, according to our old rating system.

Someone else asked about the Goodmans Axiette (spelling might be off). It's sometimes a somewhat better speaker (they did not look it, but even the ceramic version was good) , if I recall correctly. But I generally prefer other European products. There are also some fantastic all-paper 8-inch cones with whizzers (Jensen, GE, even Quam, Magnavox, Zenith, Oxford, all sorts of stuff) that you can find. Additionally, there's some interesting high-gauss British equipment, such as Bakers and at least one model of Whitely Stentorian, among other items. It's always exciting to find them when you can.

There are some highly detailed full-range Jensens available, and other similar products, but they don't quite achieve the separation and resolution of others. However, Jeb98, you make a good point that with EQ adjustments, proper on-axis positioning, and other tweaks, you can get surprisingly close to WeCo quality, sometimes.

I know my opinions can be controversial, but if you ask me, open baffle is the way to go if conditions allow. Most cabinets are either too stuffy or resonant, although there are tricks to mitigate this. There are a few flat cabinets that don't interfere with the tone, but they don't add anything either, which is the best possible outcome.

The 618 box is quite useful, but it does have that woody boom that JE mentions. It's pleasant and has slightly more bass, old-school style, so you might really enjoy it with the right amplifier. It's basically the WE spec box, with a bit of extra volume added, as far as I remember. Walt used to build them (and bigger versions) back in the da, before he went to the Airwave cabinet. Simple is good in this case.

The woody-warm bass is due to a couple of factors: Altec didn't use much bracing, and they used very thin plywood. I'm not kidding; it's much thinner than what most people would build with today. It actually contributes to the pleasant sound of the cabinet, but it's not flat. I recently sold an original set to a local customer. There was minimal bracing and usually no insulation. Altec used 50's Douglas Fir Pine or some kind of heart pine in the laminates. It's just plywood, but it's very old and has the right sound for audio. I've recently started building 8-inch cabinets out of solid white and yellow heart pine and have achieved similar results.

I've spoken with projectorcollector on a few occasions about his reproductions. I think I convinced him to use flooring-grade pine plywood instead of birch to improve the authenticity. However, I believe costs were mounting on his end, so I'm not sure if he's still doing it. The cabinet is relatively simple to build, so I would focus more on materials than on skill. It would be interesting to emulate Altec's curious and inexpensive build quality to replicate the sound. Fortunately, the glass-reinforced hammertone paint finish is still available, if anyone is interested. However, I would probably opt for natural shellac.

Just like with open baffle, you get better performance from the 755 if you run the 618 cabinet with the cabinet leaning off of it a bit. This reduces bass but improves the midrange.
One other thing worth mentioning is that your observations about the bass response of the 755A unit-to-unit is absolutely correct, as I have handled many over the years. Sometimes the differences are due to voice coil alignment or dirt in the gap, but other times there's just a variance in factors like cone compliance. They all sound a bit different, so it's best to match them up and sell them in pairs, like I used to do and still sometimes can.

These days, I prefer to pull T/S parameters on them, as the differences become apparent, and I like to align them as closely as possible. The bench Fs of a 755 is not that low – most of them run around 95-105 Hz, give or take. Nowadays, there are 8-inch full-range speakers that can go as low as an old 15-inch woofer (40-50 Hz), albeit with serious trade-offs.

Lastly, I wanted to give further credence to the counterintuitive practice of comparing speakers/transducers via YouTube videos. As long as the recording is done with a good microphone and you have a pair of headphones or monitor speakers you trust (I recommend Yamaha NS-10s for that, which is another controversy), things stay "relative" and you can actually compare the tonality and quality of speakers, at least to some extent. I do it all the time, and when I get the real thing in front of me, I can't say I've ever really been led astray significantly. After all, this approach isn't much different than what a mix-down engineer or mastering engineer would do in a studio – listening to a "recording of a recording" on a known monitor, etc.

👍 open baffle fan here

 

[jeb98]

I just wanted to drop in and say that this was a great discussion. Jeb98, I'm pretty sure I generally agree with your assessment of the 755's strengths in clarity. They don't go low and they don't go super high. There are other high-performing full-range 8-inch drivers that can reach higher and lower frequencies. Some are truly exceptional. I've always appreciated the quality of 50's Matshushita PiM series in general, in all variations (as well as other stuff like Coral and early Fostex). However, we (generally) never really heard anything that could compete with top-tier 4.5-5 "star" speakers, according to our old rating system.

Someone else asked about the Goodmans Axiette (spelling might be off). It's sometimes a somewhat better speaker (they did not look it, but even the ceramic version was good) , if I recall correctly. But I generally prefer other European products. There are also some fantastic all-paper 8-inch cones with whizzers (Jensen, GE, even Quam, Magnavox, Zenith, Oxford, all sorts of stuff) that you can find. Additionally, there's some interesting high-gauss British equipment, such as Bakers and at least one model of Whitely Stentorian, among other items. It's always exciting to find them when you can.

There are some highly detailed full-range Jensens available, and other similar products, but they don't quite achieve the separation and resolution of others. However, Jeb98, you make a good point that with EQ adjustments, proper on-axis positioning, and other tweaks, you can get surprisingly close to WeCo quality, sometimes.

I know my opinions can be controversial, but if you ask me, open baffle is the way to go if conditions allow. Most cabinets are either too stuffy or resonant, although there are tricks to mitigate this. There are a few flat cabinets that don't interfere with the tone, but they don't add anything either, which is the best possible outcome.

The 618 box is quite useful, but it does have that woody boom that JE mentions. It's pleasant and has slightly more bass, old-school style, so you might really enjoy it with the right amplifier. It's basically the WE spec box, with a bit of extra volume added, as far as I remember. Walt used to build them (and bigger versions) back in the da, before he went to the Airwave cabinet. Simple is good in this case.

The woody-warm bass is due to a couple of factors: Altec didn't use much bracing, and they used very thin plywood. I'm not kidding; it's much thinner than what most people would build with today. It actually contributes to the pleasant sound of the cabinet, but it's not flat. I recently sold an original set to a local customer. There was minimal bracing and usually no insulation. Altec used 50's Douglas Fir Pine or some kind of heart pine in the laminates. It's just plywood, but it's very old and has the right sound for audio. I've recently started building 8-inch cabinets out of solid white and yellow heart pine and have achieved similar results.

I've spoken with projectorcollector on a few occasions about his reproductions. I think I convinced him to use flooring-grade pine plywood instead of birch to improve the authenticity. However, I believe costs were mounting on his end, so I'm not sure if he's still doing it. The cabinet is relatively simple to build, so I would focus more on materials than on skill. It would be interesting to emulate Altec's curious and inexpensive build quality to replicate the sound. Fortunately, the glass-reinforced hammertone paint finish is still available, if anyone is interested. However, I would probably opt for natural shellac.

Just like with open baffle, you get better performance from the 755 if you run the 618 cabinet with the cabinet leaning off of it a bit. This reduces bass but improves the midrange.
One other thing worth mentioning is that your observations about the bass response of the 755A unit-to-unit is absolutely correct, as I have handled many over the years. Sometimes the differences are due to voice coil alignment or dirt in the gap, but other times there's just a variance in factors like cone compliance. They all sound a bit different, so it's best to match them up and sell them in pairs, like I used to do and still sometimes can.

These days, I prefer to pull T/S parameters on them, as the differences become apparent, and I like to align them as closely as possible. The bench Fs of a 755 is not that low – most of them run around 95-105 Hz, give or take. Nowadays, there are 8-inch full-range speakers that can go as low as an old 15-inch woofer (40-50 Hz), albeit with serious trade-offs.

Lastly, I wanted to give further credence to the counterintuitive practice of comparing speakers/transducers via YouTube videos. As long as the recording is done with a good microphone and you have a pair of headphones or monitor speakers you trust (I recommend Yamaha NS-10s for that, which is another controversy), things stay "relative" and you can actually compare the tonality and quality of speakers, at least to some extent. I do it all the time, and when I get the real thing in front of me, I can't say I've ever really been led astray significantly. After all, this approach isn't much different than what a mix-down engineer or mastering engineer would do in a studio – listening to a "recording of a recording" on a known monitor, etc.

Thanks for the detailed response! I agree that the separation and resolution of the Western Electric stuff is amazing.

I have heard the 755a in an open baffle setup with an assortment of single ended triode amps and the midrange was stellar. But, the bass was just not enough for me. I start to get used to the sound of the 755a and then I switch to another more full range 2 way speaker set up and I'm like, oh there's the bass i was missing.

I am going to try and play around with a sub on the 755a. Have you ever found a sub to work with the 755a? I was using subs with my 757 "reproductions". These had a very well matched pair of 728B and I wasn't getting enough bass. I found the subs to integrate well personally. I imagine I could get subs to work with the 755a without ruining the midrange or the highs? Or maybe not.

I'd like to try the 618 cabinets. I still need a 2nd 755a, which will be hard to find with the zinc 755a I have, which seem to be less common than the Altec 755a. I've also been in touch with Projector Collector and he said he may do another run of the 618 cabinets.

Interesting what you said about finding a matching pair. I'm sure this will be hard for me to accomplish.

I recorded a few videos of the 755a vs the PIM8. Maybe I'll post them. Actually I'll go back and record some more for a fun comparison.

Best,

Jonas

 

[skynet]

Thanks for the detailed response! I agree that the separation and resolution of the Western Electric stuff is amazing.

I have heard the 755a in an open baffle setup with an assortment of single ended triode amps and the midrange was stellar. But, the bass was just not enough for me. I start to get used to the sound of the 755a and then I switch to another more full range 2 way speaker set up and I'm like, oh there's the bass i was missing.

I am going to try and play around with a sub on the 755a. Have you ever found a sub to work with the 755a? I was using subs with my 757 "reproductions". These had a very well matched pair of 728B and I wasn't getting enough bass. I found the subs to integrate well personally. I imagine I could get subs to work with the 755a without ruining the midrange or the highs? Or maybe not.

I'd like to try the 618 cabinets. I still need a 2nd 755a, which will be hard to find with the zinc 755a I have, which seem to be less common than the Altec 755a. I've also been in touch with Projector Collector and he said he may do another run of the 618 cabinets.

Interesting what you said about finding a matching pair. I'm sure this will be hard for me to accomplish.

I recorded a few videos of the 755a vs the PIM8. Maybe I'll post them. Actually I'll go back and record some more for a fun comparison.

Best,

Jonas

Found this onlin

Vintage Speaker Cabinets Altec Western Electric Era 600B 755A | eBay

 

[jeb98]

Found this onlin

Vintage Speaker Cabinets Altec Western Electric Era 600B 755A | eBay

Thanks. I saw those they don’t seem to be made by Altec or WE, and also for 12 inch drivers. Im still looking for a second 755a anyway. Thanks for letting me know, I appreciate it!

Best,

Jonas