Interest check on speaker design from reputed US speaker guru

[GeorgeO]

Hi Phil

Welcome to Hifivision, good to see you lurking here.

George

 

[captrajesh]

It is a great privilege to have you with us Mr. Bamberg; welcome to the forum.

 

[kapvin]

I am here lurking.

Welcome to HFV, Mr. Bamberg!

 

[navin advani]

This was couple of project I always wanted to try
Jensen-1071

Norge is a dealer of wavecor drives

I am not familiar with Wavecor drivers, will do some research.

Yes thats also my understanding about Peerless India. In fact Tarun (TCPIP) has had similar issues in the past, so the reality unless Jeetubhai can solve it may be that we may have long term supply issues with some models.

I am here lurking.

May I chip in?

Firstly, it is superb of someone of Philip's talents to offer them to a very small DIY community (aka India).

I would, however at this stage, like to play devil's advocate just because I have travelled down this road before and found that it often lead to nowhere.

There are 2 challenges we face with drivers from Peerless India.

a. Availability - this might be resolved through the famed Jeetubhai
b. Adherence to published specifications - don't get me wrong almost all drivers deviate from published specifications. While a 10% variation is normal and can be accomodated in most designs a 50% variation is not. The Peerless drivers I tested (albeit many many years ago) suffered from such huge variations that the only solution I could find was sealed box (which is much more tolerant).

Now coming the to issue of Wavecor/Norge. I am an old friend of Shyam's; in that I am both old and a friend of Shyam's.

Wavecor drivers are imported. A few of them did have some issues with tolerances but I believe these have been ironed out. Allan Isaksen is a wonderful chap and if we can get enough volumes this might be your best route.

 

[Philip Bamberg]

I began working with Wavecor drivers 3 years ago, and I can vouch for their quality. However, my own product line has new models with Wavecor, and that instantly becomes an internal conflict of interest for me. OTOH this may be a way for an authentic Bamberg design to be made available to the group but at a much lower cost, since it is DIY. I will have to ponder whether I will sign up to do a design based on Wavecor. For one, Allan may require a minimum 250 units to be purchased, or else point us to a retailer.

There are surely many reasons for this project to derail. This sort of group project has been tried many times before, with the primary challenges being resolving many opinions into a single action plan, financial issues, and the timeline for it all.

The more participants, the better the financial issue becomes, but the more likely it is for dissent within the group on the final speaker design, and the longer the timeline becomes. One example years ago here in the US was when a group "reference" 2-way bookshelf project stretched out for about two years before everyone gave up in frustration. It was a classic example of too many voices over-analyzing the smallest details, and with very little consensus. All this for a 2-way bookshelf speaker. I proposed that the project became a new definition for the term "group delay". :lol:

We don't want this to evolve into an untenable monster project, but good project management is sorely needed in order to pull it off with success. It really is best for everyone to "zoom out" and discuss the big picture items first. That is, start a sign-up list to gauge interest, determine the driver source, and then discuss the speaker format.

 

[bijinmb]

Yes thats also my understanding about Peerless India. In fact Tarun (TCPIP) has had similar issues in the past, so the reality unless Jeetubhai can solve it may be that we may have long term supply issues with some models. Does anyone here know Jeetubhai well enough to ask the questions?

Many of our FM assumption/guess is wrong.

If we have quantity, they can provide you almost any model which is not offload export surplus.

But IMO we need to measure whatever drivers we procure, with proper measurement tool since the tolerance range is high as compared to their factory provided spec.

Another option is Dayton Audio since they have wide range of drivers to fit almost any requirement and budget.

 

[captrajesh]

If their drivers (presumed to be from the same batch, pragmatically speaking) have such widely different parameters as couple of our FMs are saying, I doubt if any reputed speaker manufacturer would source drivers from them.

 

[diesel engine]

I began working with Wavecor drivers 3 years ago, and I can vouch for their quality. However, my own product line has new models with Wavecor, and that instantly becomes an internal conflict of interest for me. OTOH this may be a way for an authentic Bamberg design to be made available to the group but at a much lower cost, since it is DIY. I will have to ponder whether I will sign up to do a design based on Wavecor. For one, Allan may require a minimum 250 units to be purchased, or else point us to a retailer.

There are surely many reasons for this project to derail. This sort of group project has been tried many times before, with the primary challenges being resolving many opinions into a single action plan, financial issues, and the timeline for it all.

The more participants, the better the financial issue becomes, but the more likely it is for dissent within the group on the final speaker design, and the longer the timeline becomes. One example years ago here in the US was when a group "reference" 2-way bookshelf project stretched out for about two years before everyone gave up in frustration. It was a classic example of too many voices over-analyzing the smallest details, and with very little consensus. All this for a 2-way bookshelf speaker. I proposed that the project became a new definition for the term "group delay". :lol:

We don't want this to evolve into an untenable monster project, but good project management is sorely needed in order to pull it off with success. It really is best for everyone to "zoom out" and discuss the big picture items first. That is, start a sign-up list to gauge interest, determine the driver source, and then discuss the speaker format.

Guru, welcome to HFV!
As of the sign-up list, I am in.

 

[tcpip]

Guys,

Saw this thread just now. Interesting discussions.

I am surprised that we are still mentioning "Jeetubhai" when discussing Peerless India drivers. I have documented how things have moved from Jeetubhai to Mayank, his son, and we now all know that diyaudiocart supplies these drivers with reasonable assurance of availability, therefore things are far better than they were when I did the Asawari Mark I. I also feel that we should not restrict ourselves to Peerless India drivers when bajaao.com is making available Dayton drivers easily too. The Dayton RS drivers are excellent.

I am more worried about what Navin and Phil have written -- a "group design" project rarely flies because everyone has an interest in chipping in with opinions, but very few are in a position to use those opinions to create a well-engineered design. Group buys and group builds are doable, but group designs remind me of the line "A camel is a horse designed by a committee." It may be more practical if Phil plays with a few Peerless (or other) drivers, and designs a couple of speakers out of them as per his own judgment, and then we pay Phil when we pick up the design details from him, with a pledge that we will not re-distribute his intellectual property among our friends. That's sort of the way Linkwitz' LX521 is made available to the DIY community, if I'm not mistaken?

I am also curious to know why we are simply stopping at choosing drivers available in India. What about good capacitors? Who will make coils? AFAIK, there are no custom coil winding services available for DIYers in India.

Hope the project flies. I will be keenly following the thread.

If their drivers (presumed to be from the same batch, pragmatically speaking) have such widely different parameters as couple of our FMs are staying, I doubt if any reputed speaker manufacturer would source drivers from them.

Actually, manufacturers usually work this way -- their raw products coming out of the line have wide parameter variance. They then do a measurement pass and deliver the QC-passed pieces to their customers, and release the balance without the model number (or with a different model number) in the surplus market. This is like Intel's chips -- the high-clockspeed ones are just part of the normal batch, but are tested and selected after manufacturing and labelled with the high clockspeed label.

Peerless India's drivers are comparable to midrange drivers made by many other international brands -- I did not see any fundamental issue in quality. If you want to see parameters jumping all over the map, you have to look at other manufacturers -- Bolton of Delhi, for instance.

b. Adherence to published specifications - don't get me wrong almost all drivers deviate from published specifications. While a 10% variation is normal and can be accomodated in most designs a 50% variation is not. The Peerless drivers I tested (albeit many many years ago) suffered from such huge variations that the only solution I could find was sealed box (which is much more tolerant).

Hi old friend,

I have a feeling your observations may be more applicable, or less, depending on which Peerless India drivers you pick up. Some of their older drivers with stamped steel sheet frames seem to be less "precisely made" if I may use the term. The more recent drivers, e.g. midbass units with Kevlar cones and polycarbonate baskets, are much better made and will probably show much closer tolerance. Try them. They're pretty decent.

 

[Hari Iyer]

Its always better .to measure the actual impedance and resonance before building the system.I have observed matched kevlar drivers have the same actual impedance and resonance behavior offered by Peerless. Even the matched aluminium dome tweeter has the same voice coil resistance. Not sure whichdrivers from Navin had huge tolerances. I would suggest getting matched pair from peerless always.

 

[tcpip]

I have observed matched kevlar drivers have the same actual impedance and resonance behavior offered by Peerless. Even the matched aluminium dome tweeter has the same voice coil resistance. Not sure whichdrivers from Navin had huge tolerances.

My limited experience with four Kevlar midbass drivers when I built the Asawari Mark I were good too. They had close enough tolerances for me to not have to worry about "matching" anything.

 

[keith_correa]

Its always better .to measure the actual impedance and resonance before building the system.I have observed matched kevlar drivers have the same actual impedance and resonance behavior offered by Peerless. Even the matched aluminium dome tweeter has the same voice coil resistance.

"Matched" drivers would be close in specs else they would not be called "matched" right?

Not sure whichdrivers from Navin had huge tolerances. I would suggest getting matched pair from peerless always.

Who is selling them as "matched" pairs? Jeetubhai/Mayank/Peerless?

And if building other than a TM, more than a "matched" pair would be needed

 

[tcpip]

"Matched" drivers would be close in specs else they would not be called "matched" right?

Don't know about Hari, but I never bought any matched pairs -- I just got them physically tied in pairs, the way they always seem to pack their Peerless woofers. I got four, and measured all four (for the Asawari Mark I, which is an MTM) and I found parameter variations were very much within acceptable range. I did not have to tweak the crossover component values for the two channels.

 

[GeorgeO]

If the numbers add up and the final design is an MTM, I wonder what kind of numbers(buyers) make sense for a designer like Phil to offer design to our members? The other side of the coin is the number of units from the seller's pov for him to offer a special price, if there is a group buy.

 

[Hari Iyer]

As i usually build TLs the only important paramter for the box is Fs, Vas and Qts. As far as crossover is concerned its just Rvc, Lvc and actual Z at Fc. If they are within 1% then challenges later will be minimum. Not sure what parameters to consider for other box loadings.

 

[Philip Bamberg]

Guys,

Saw this thread just now. Interesting discussions.

I am surprised that we are still mentioning "Jeetubhai" when discussing Peerless India drivers. I have documented how things have moved from Jeetubhai to Mayank, his son, and we now all know that diyaudiocart supplies these drivers with reasonable assurance of availability, therefore things are far better than they were when I did the Asawari Mark I. I also feel that we should not restrict ourselves to Peerless India drivers when bajaao.com is making available Dayton drivers easily too. The Dayton RS drivers are excellent.

I am more worried about what Navin and Phil have written -- a "group design" project rarely flies because everyone has an interest in chipping in with opinions, but very few are in a position to use those opinions to create a well-engineered design. Group buys and group builds are doable, but group designs remind me of the line "A camel is a horse designed by a committee." It may be more practical if Phil plays with a few Peerless (or other) drivers, and designs a couple of speakers out of them as per his own judgment, and then we pay Phil when we pick up the design details from him, with a pledge that we will not re-distribute his intellectual property among our friends. That's sort of the way Linkwitz' LX521 is made available to the DIY community, if I'm not mistaken?

I am also curious to know why we are simply stopping at choosing drivers available in India. What about good capacitors? Who will make coils? AFAIK, there are no custom coil winding services available for DIYers in India.

Hope the project flies. I will be keenly following the thread.

I think tcpip has it about right on all counts.

It would be more expedient if I simply offered a design that is already complete and tested. In fact I have one right now - a 2.5-way MTM with Peerless 15cm midbass and Vifa neo tweeter. Would make a good LCR. But this is Tymphany Peerless.

I only suggested Peerless India as a means to keep your shipping costs down. Does Parts Express have an outlet over there, or is their US ship costs reasonable? Either way, they carry the drivers in this design.

As for driver parameters, I am not worried about TSP for the low end, because the box alignment dominates over the parameter variance. However, consistency in the upper range is more important to me, since the interaction with the crossover is much more sensitive.

 

[navin advani]

One example years ago here in the US was when a group "reference" 2-way bookshelf project stretched out for about two years before everyone gave up in frustration.

I believe Phil you are referring to this.
diyAudio reference speaker project - diyAudio

It is not always that bad. Many years before this the Bass Digest had a group subwoofer project based on the NHT1259. That ended quite successfully. In fact Mike Dzurko of ACI also extended his help with the DV12 woofers (I know I ordered 6!).

However yes, unless we have a clear goal as to what the speaker will do, will cost and will look like (only a lucky few don't have to live with WAF) this project can end up like the diyaudio project above. However many of the members who participated in that discussion went on to build other projects like the Ariel or Daline.

Now we have another thread that might go nowhere.
DIY Audio 3-way reference project?? - diyAudio

The Dayton RS drivers are excellent.
What about good capacitors? Who will make coils?

Why not group import the caps and coils too. I did; and I was flying solo when I did this.
Pictures of Selah designed Tempesta Extreme and RC4 (no subwoofer)

I have a feeling your observations may be more applicable, or less, depending on which Peerless India drivers you pick up.

I specifically refer to the 4 831727s I picked up from Peerless India (via Choudry trading corp) in the late 80s. That was the time I was working on a corner loaded subwoofer for the Dynaudio Gemini (15W75-D28af MTM)..oh BTW if you ever do build this speaker try a series XO like here.
http://www.htforum.nl/yabbse/index.php?topic=56666.0

After that experience I did try P.I. drivers twice and found that their published specs did not match the measured spec (using LEAP LMS) but the drivers themselves were not too far apart so often what was visualised as ported design ended up being a sealed box.

I found parameter variations were very much within acceptable range. I did not have to tweak the crossover component values for the two channels.

Driver to driver variations are not bad, measured to published variation is greater.

I only suggested Peerless India as a means to keep your shipping costs down. Does Parts Express have an outlet over there, or is their US ship costs reasonable?

However, consistency in the upper range is more important to me, since the interaction with the crossover is much more sensitive.

Phil, this group has shown the ability to both design speakers like the Asawari and Darbari (both designed by TCPIP) and work cohesively (as in the AV123 group buy) as can be seen in the links below.

http://www.hifivision.com/diy/46666-asawari-mark-ii.html
The Darbari | dhandanought.org | tcpip
http://www.hifivision.com/diy/19688-best-ever-deal-loudspeaker-kits.html

Sadly, I will not be participating in the build/buy as I go way too many speakers at present and my wife is threatening to throw me out. For the same reasons I am now disbarred from adding to my single malt collection so I am going to live vicariously through my fellow HFVians here.

 

[Hari Iyer]

Sadly, I will not be participating in the build/buy as I go way too many speakers at present and my wife is threatening to throw me out. For the same reasons I am now disbarred from adding to my single malt collection so I am going to live vicariously through my fellow HFVians here.

Same with me, with my new TL FS speakers, my wife is always asking me if these pair is going to stay here for the rest of our lives. When I said yes, she gave me a crooked look and said on no. Check out here http://www.hifivision.com/speakers/49825-new-linear-tl-floor-standers-my-next-upgrade-845-tubes.html

 

[tcpip]

Driver to driver variations are not bad, measured to published variation is greater.

Understood. I never paid heed to the published figures of Peerless India, but I must admit that their 6.5" Kevlar drivers' published specs were very close to the ones I have used and measured. Including the Vas.

I only suggested Peerless India as a means to keep your shipping costs down. Does Parts Express have an outlet over there, or is their US ship costs reasonable? Either way, they carry the drivers in this design.

Bajaao.com stocks and sells many drivers which Parts Express sells. I have had good experiences dealing with this reseller, but some others on these forums have had problems. And about prices, there is divergence of opinion whether the markup applied by Bajaao.com is "fair" or not.

My limited experience with four Kevlar midbass drivers when I built the Asawari Mark I were good too. They had close enough tolerances for me to not have to worry about "matching" anything.

I recently chanced upon some drivers lying around, while I was playing with my impedance jig. So I decided to measure two 4" paper-cone Peerless India drivers from a lot I had bought many years back, to see how they match against each other. Nothing "matched pair" about them -- I had picked them up from a shop in L. Road.

I didn't measure Vas because it's a pain to measure (you need a small sealed box and you need to mount the driver in the baffle of the box), but the rest of the key attributes are as given below:

Parameter:     DIYcart      Sample1      Sample2
Fs (Hz):         80            89           93
Qes:            0.57          0.76         0.80
Qms:            2.14          2.96         2.97
Qts:            0.45          0.60         0.63
Le:             ---           0.15         0.16
Re (Ohm):       5.8           5.82         5.73

The first column is values from the diyaudiocart Website -- it has reproduced the values Jeetubhai had given me on terrible photocopies of terrible datasheets. Can't blame diyaudiocart -- this is all they have. The second and third columns are from my measurements. All the values I have given were calculated by Speaker Workshop from the measured impedance curve (yes, even the Re).

As you can see, the measured values do not match well with the published ones. This has been my experience with most Peerless India drivers. I suspect that their parameters change from batch to batch. However, the measured values match well with each other, indicating terrible publishing of updated documentation, but consistent manufacturing.

The attached graph is of the impedance curves of the two drivers. The match that I am seeing is good enough for me to measure one driver and build multiple units. However, if I buy drivers in multiple lots with a big gap of time in between, I will re-measure.

 

[Hari Iyer]

Re: How well do Peerless India drivers match in their parameters?

The datasheet handed over by Jeetubhai should be taken with a pinch of salt. I even doubt if his model nbrs are matching with the datasheet. Unless you are able to measure the drivers provided by him, do not attempt to build with Peerless drivers looking at his datasheet, you will fail badly.