Overhaul: Pro Kennex Black Ace 98

Having experienced the sweet and pure ball contact on the stringbed, it is difficult to settle for less.

I cannot reconcile the thought of such a harsh racket (hammer5.8) playing so much smoother and comfortable than a Pro Kennex. It justs defies all logical thinking!

Rather than vacillating, I decided to act!

After taking the measurements, I stripped the overgrip, replacement grip and buttcap from the Black Ace.

Interestingly, the buttcap is entirely made of rubber. And it's quite soft, weighing about 9g.

What I saw inside the handle surprised me! It was not foam filled! The handle is completely hollow all the way up to the  frame, just like the Dunlop Mfil300!

The other interesting observation I wasn't aware of, is the the Black Ace seems to use a grip pallet system. The pallet is held together by masking tape. You can see the pic below. I don't know if this is original as I have not used Pro Kennex rackets before.

To think that a completely hollow racket can feel and play so solid is very impressive. If you take another look at the racket butt picture above, the graphite looks "dirty". There is a lot of yellowish-brown speckles embedded together with the graphite. Could this be the secret formula for PK?

Whatever the case, I did a similar frequency-based vibration dampening for the Black Ace as the hammer and mfil300. Both hollow ends are filled then plugged with foam.

The specs (old/new):
Total weight(g): 339/345
Grip size: 4 1/4 / 4 3/8
Balance(mm): 322 / 320
Swingweight: 331 / 335 (estimated)

26Jun2013 update:
- The feel of the ball contact improved tremendously.
- It is not fair to attribute the improved feel entirely to the modification. Previously, the racket was gripped with the Wilson Comfort Hybrid Replacement Grip. (link) It weighed about 18g and muted the feel a lot. I know because I bounced a ball holding just the bare pallet, and it was so much livelier although the vibrations were magnified too.
- Over the past three racket overhauls, I noticed that any foam or extra shock absorbing grips tend to deaden overall feel. On the contrary, inserts inside the handle seem to reduce only harsh vibrations.
- Ball contacts are now much crisper. The feedback is cleaner, "louder" and stronger. As a result, there is absolutely no doubt now where ball impacts are made. There is a clear distinction between sweetspot and off-sweetspot hits.
- With off-centre hits now, instead of harsh vibrations, it is now mainly a "thud" and the ball departs with very low power. Previously, it was slightly harsher, not a stinging pain, but still a little uncomfortable.
- Overall, there is improvement but the change is small compared to the hammer and mfil300 as this is already a comfort-oriented frame to begin with.
- From the darkened patch of string wear, it seems I am hitting a little too high. The sweetspot is slightly lower. If I can move the dark patch about 3 cross strings lower, I think it would be perfect!

29Jun2013 update:
- Took this out for some rally and drills today. I feel the optimum balance and swingweight is still elusive.
- The racket feels very solid and stable no doubt. But some unknown element is missing. I cannot explain it. Could it be the very soft flex of RA58 that I am not used to?
- After the session, I dismantled the grips and buttcap, removed all the "stuffings" and restored it back to stock again.
- I did the calculations one more time and decided to do an extreme weight polarisation. That would add swingweight most efficiently and help to stiffen the dynamic flex of the frame.
- Specs after polarisation:
     - Total weight(g) = 346
     - Balance(mm) = 330
     - Swingweight = 345 (estimated)
- I will update after my next session.

01Jul2013 update:
- I finally got the swingweight setup correctly, or at least very near to what I like.
- Once the swingweight is done, it becomes much easier to "diagnose" since a critical variable is eliminated.
- The unknown missing element is pocketing. There is very very little pocketing during ball impact. Almost none. Which explains my lack of "feel" and accuracy. I believe this has to do with the very soft flex.
- I have to re-think how to string this racket to "open up" the pocketing potential. That would make the racket feel "stiffer" during play.
- I managed to "move" the ball contact area slightly down. You can see the centre of the dark patch of string wear is now around the 9th cross string compared to about the 7th cross string in the previous picture.

Comfort Challenge: Hammer vs Mfil300 vs Black Ace

After the overhaul of the hammer (link1)(link2) and mfil300 (link1)(link2), I was asked if I could pitch them against a Pro Kennex. 

I thought it made sense. Which is why I got the Black Ace 98 (link) to do this sinister comparion...

The hammer and mfil300 were strung with poly/syn gut and syn gut respectively. Some may argue it's an unfair competition, but I think the results should still hold and will be pretty fast and decisive.

Only my regular partner, M and myself would be doing the tests.

My objectives are to:
1. understand how an arm friendly racket ought to play like,
2. ascertain if a harsh racket can made to play arm friendly,
3. find out if my frequency based mod is repeatable,
4. satisfy our curiousity.

	Hammer5.8	Mfil300	Black Ace 98
Strings	Poly Centre/Syn Gut perimeter	Syn Gut Full Proportional Stringing	Syn Gut Partial Proportional Stringing
Tension (lbs)	45/42	60	35
Length (inches)	27	27	27
Head Size (sq in)	95	98	98
String Pattern	16x19	16x19	18x20
Flex	65	61	58
Total weight (grams)	338	338	339
Balance (mm)	327	325	322
Sweetspot feel	9.5/10	8.5/10	6/10
Off-sweetspot feel	8.5/10	8/10	6/10
Sweetspot vibrations	Almost none	Very little	Clearly felt
Off-sweetspot vibrations	Almost none	Very little	Clearly felt
Power	8.5/10	7.5/10	6.5/10
Accuracy	9/10	8.5/10	7/10
Spin	7/10	8/10	8/10

ProKennex Black Ace 98 + Syn Gut @ 35/34 (Box)

Many claim that Pro Kennex rackets represent the pinnacle of racket comfort and arm friendliness.

The acid test for any rackets claiming to be comfortable is to pitch it against a Pro Kennex. Any Pro Kennex.

I already have one. (link) But that is just an entry level. To be fair, I got the Black Ace 98, which I'm told is decent enough to hold its own and represent the PK family.

I think this is the 2009 version of the Black Ace 98. Specs below:
Length: 27 inches
Head Size: 98 sq inch
Weight: 332g strung
Balance: 33cm / 13" / 4 points headlight (mine's at 32cm)
Flex: 58
Swingweight: 331
Construction: 19mm straight beam

To push comfort to the max, I will string it with full synthetic gut at ELT of 35lbs. And box the perimeter stringbed with proportional stringing to add dampening. That will really open up the sweetspot!

Stringing pics below, using box stringing pattern...

This is a 18x20 pattern, so I did up the centre 6 mains on each side first.

First box in below pic.

Then the second and third box are done before the rest of the crosses.

Since I wanted to tie-off at the fourth cross from the bottom, I filled the fourth bottom cross first so I could tie on it later.

A close-up view below to check if I've weaved the crosses correctly during the boxing.

In case you're curious about that little red bead thingy in some of the above pics, it's a self-made starting pin using a piece of scrap poly string.

Playtest:
- From the first few hits, it immediately seemed like I had expected too much from PK.
- Everything is so muted. So dampened by the frame that there is so little feedback.
- Without discussing our opinions, my partner and I rotated several different rackets and then back to the Black Ace a few times. The general consensus is that both sweetspot hits and off-sweetspot hits felt so equally muted that it is sometimes hard to tell where we contacted on the racket face!
- Spin is much better than most 18x20 as I've also noticed the bigger spacing between the strings.
- I cannot tell if it is due to the soft flex, but accuracy does not seem too good. Most attempts to aim down the baseline  missed left or right. My successful hits with other rackets fared so much better.
- It may sound surprising, or even insulting, but both of us felt hints of nasty vibrations even with the super muted feel.
- The racket feels solid and I think the frame is most probably foam-filled, but even then, it still plays "noisy". The feedback is not clean and crisp. There is no difference between good and bad contacts.
- I'll give this another try next session.
- The first pic shows the string movement and ball fur after about 20 minutes. 

- The second pic is after about 60 minutes of play and there is a dark spot starting to appear on the sweetspot from ball friction. I think my sweetspot contact percentage should be quite acceptable.

Overhaul: Dunlop Mfil300

With the recent haze, it has become quite hazardous to play tennis. To avoid the air pollution, many have even chosen to stay indoors.

Take a look and see how bad it is...

Instead of playing, I'll use this time to "fix a problem" I inadvertently created.

It all started with a previous racket overhaul. (link)

That Wilson hammer series was notorious for its harsh feel, head heavy balance and was blamed for many wrist and elbow injuries. 

That's why I overhauled it. But the experiment was too successful. Now, with almost zero harsh vibrations and headlight balance, that hammer has become my preferred racket! I like it more than even my ProStaff 6.0, ProStaff Classic and XT80. See the problem?

Since I cannot play, I'll do another racket to test if the previous mod is repeatable or a fluke.

The Dunlop was chosen due to its stiff and hollow feel. The stock lightweight (309g strung, link) provides ample room for "stuffings." Plus, I've just re-strung and tested it with full proportional stringing! (link)

The main gist is to insert different materials into the racket to change its vibrational frequency without taking away too much feedback.

Primarily, I will be using the "Wild-Ass-Guess" method to stuff, then measure the frequencies and repeat. It will be tedious, messy and exhausting.

Here's some random pics of the process...

First step is always to measure stock weight and balance. Then plan my desired goal before commencing.

Using a straightened coat hanger, I inserted it from the buttcap to ascertain how hollow the racket is.

There was no resistance all the way. It was about 13 inches.

I removed only two staples to make a little more room for stuffings.

It's clearly visible that the handle and throat is completely hollow. Unlike the hammer which was filled with foam.

Polystyrene beads worked well previously, and it is extremely light. So I'm using some of them again. You can see half a tub of this only weighs a measly 4 grams.

A funnel is very handy. Just be sure not to spill the foam. Static electricity will cause it to "stick" everywhere and you'll have a very hard time cleaning them up later.

(The other materials I'm using is just too messy so I did not take pictures.)

Compared to the previous attempt, I completed this much faster in only 3+ hours. The ball bounce on the floor and in the air feels very very promising indeed. Solid, very little harsh vibrations with amazing sweetspot feedback.

Playtest:
- The racket played very stable and solid.
- Combined, the different materials stuffed in the frame and handle took away the hollow "tin can" feel.
- Previously, I had about 12g of lead at 12-3-9 to stabilise the frame. Even after taking off all the lead, the racket felt stable on its own now. Naturally, it moves faster too.
- All the nasty jarring vibrations disappeared completely. Yet, sweetspot hits retains its rewarding full feel and pop. Just without the "noise." Ball contacts feel very very clean.
- When swinging the racket, I can feel the added heft in the throat and handle. The weight has become de-polarised but stability has increased tremendously. It now weighs about 339g strung and gripped.
- Spin dipped slightly compared to before the overhaul.
- Accuracy improved mainly due to the added stability.
- I am beginning to like this frame!

08Jul2013 update:
- After a few swings, the racket felt a little too light compared to my usual sticks. After some calculations, I re-applied some lead tape and brought the swingweight back up to about 345 and total weight about 345g too.
- That delivered great improvement to the overall plowthrough and feel of the racket.
- Even contacts in the centre of the stringbed, where the tightest tension of 60lbs was applied, pocketing was surprising ample!
- The higher pitched "pop" sound upon ball contact came back and I remembered this sound after being away using ELT for several months.
- Spin, control and power are all complete.
- I just need to play a few games with this stick to see if I could wield it efficiently under pressure.
- Will update again.

11Jul2013 update:
- After a short warm-up, I played a set with this racket today.
- Switching back to a "normal" tension of 60lbs (proportionately strung) from ELT is very easy.
- Most significantly is that the ball rebound is much lower so I just have to aim higher. It took me less than 5 minutes to adapt back to this string tension.
- The strongest aspect of proportional stringing is the very large sweetspot. I cannot find anywhere on the stringbed that is jarring. Even some shots hit way off-centre still managed to barely clear the net.
- Power levels are very much higher than at 30+ lbs! A lot of serves and baseline shots went long and I had to throttle down the power, which is very very nice. That gave me a lot more time since a compact swing produces more than enough power.
- My regular partner also commented on my much harder serves and groundstrokes.
- So, for those that are still thinking of "trampoline" at 30lbs, you can banish that thought. Power is much lower in the 30s.
- Spin levels dropped significantly compared to ELT but control improved so it's a fair give-and-take.
- Below pic clearly shows a dark spot of string wear on the sweetspot.

16Jul2013 update:
- Played a game using this racket with M using his newly strung RD7 at 60lbs proportional (link)
- After several sessions, this strings have broken-in very nicely.
- Power seems to have increased slightly over the last session. Could it be tension loss?
- Or could it be due to the reduced amount of topspin, which previously would have "curled" the ball down earlier.
- Even on spin serves, I am unable to get the ball to curl as much as before. I definitely miss the "banana kicks" that could only be executed with ELT.
- I'm still amazed at the amount of "pocketing" I get at this tension. Of course, it is nothing compared to ELT, but still, the feel of the strings depressing upon ball contact is undeniable. So it is actually still quite comfortable.
- Directional control is very good. There is enough for me to swing all out and aim for the deep corners when returning M's second serves. A little more spin would help to make these shots kick more offensively though.
- Overall, I award proportional stringing very high marks for playability, comfort, control and an amazingly huge sweetspot. But I miss the spin from ELT sorely...
- I'm thinking, is there a way to do proportional stringing to increase the spin without sacrificing the other attributes?

19Jul2013 update:
- Power levels still seem a little too much with this racket for my preference.
- The proportion of power and spin feels off to me. For this level of power, I would prefer more spin so that control is constant, but I could not raise the amount of spin.
- I played a set with this racket today and lost to M at 3-6 after winning 6-0 while using my kevlar setup (link). I think I can blame this racket or string setup for the loss...
- The dark spot of string wear is getting darker and larger with some minor notching beginning. Tension holding is still very good.

Dunlop Mfil300 + Syn Gut @ 60 lbs (Full Proportional + Box)

Even after stringing a racket with the "Lendl pattern" (link), I was still wondering why Lendl strung it that way. What were his objectives? What problems were he trying to solve or avoid?

While the pattern can be copied, and even the same strings be used, the actual stringing steps and tensions are a little more mysterious. 

What tension was used in his mains? And crosses? Did he vary tension within the mains/crosses? How did he thread the racket? Was the natural gut pre-stretched?

All these makes a huge difference how it would play. Just like an email I received at how loose the ELT stringbed played. A blog reader attempted to copy my "varied crosses" using a crank machine. No wonder it played too soft and loose...

Going back to the Lendl pattern, I later realised that it was similar to a box stringing pattern, except that he "boxed" it with natural gut with a poly centre. That threw up a few interesting ideas for me.

I believe the box pattern is able to isolate and retain different tensions at different portions of the stringbed. Definitely much better than the standard one-piece or two-piece.

Although I am still firmly rooted in the ELT camp, some have asked me to try a full proportional stringing using a more conventional tension of 60 lbs. I thought this will be an interesting comparison with ELT. Perhaps even challenge ELT?

My objective with full proportional stringing is to:
1. try to enlarge the sweetspot, and/or,
2. increase dampening around the stringbed perimeter, and/or,
3. stabilise the rebound angle while maintaining comfort.

From my research online, the greatest danger seems to be frame warp or cracks due to uneven pressures. 

The strange part is that, these same people who issued these warnings have either never strung full proportional before or, have tried it before but have never experienced a frame crack.

Neither could I find a single article online about a frame crack due to full proportional stringing! Not a single one! Sounds fishy to me, don't you think? Or are they trying to hide something?

Whatever the case, I am taking measurements first... both length and width...

This racket has a 16x19 pattern. The centre 10 mains are strung first. Within these 10 strings, there is already a 10lb difference between the tightest and loosest.

I am starting the "box" with the 6th right main from top to bottom. If you observe the left floating clamp, you may deduce that I strung L1, L2, L3, L5 then L4. I tied-off the short side at Top5.

As seen below, the first box is completed.

The pic below shows the second and third box being done. Proportionately, these outer mains and crosses tension are pulled in the 20 to 30 lbs range.

Filling in the remaining crosses below at between 30+ to 50+ lbs. 

Once completed and dismounted, measurements are immediately taken to check if the amounts of warp are within acceptable range.

Length increased 1mm whereas width has narrowed by 5mm. It's just a tad outside of my usual warp range of about 3-4mm so I can still accept it. 

What this proves to me, is to drop the tension a little on the crosses if I were to do this again. I had doubted the numbers for the crosses so I did up them by a few pounds.

I'll measure the length and width again after I clock-in some play. 

Bouncing a ball on the floor and in the air feels very good indeed. The harsh spots previously felt disappeared. The sweetspot does feel significantly enlarged.

Playtest:
- Within the first few hits, the immediate observation is how accurate the strings were. Even though only the longest few centre main strings were pulled at 60lbs, but the directional accuracy is "straight as an arrow!"
- The part that is hard to reconcile is that, while it feels like a normally strung (ie high 50s to 60+ lbs) racket, the sweetspot is SO HUGE!!! 
- Both my partner and I just cannot find any dead spots! Everywhere was nice and comfortable without any harsh vibrations. I recall distinctly how small the sweetspot played with previous stringjobs. That's why this racket stayed in the cabinet, but now, all has changed!
- Power levels are in between a full ELT and full 60lbs. In other words, it's more powerful than pulling every string at 60lbs but less powerful than ELT.
- My playing partner liked this stringjob from the first hit and was thinking which racket to send over to get this full proportional stringing done.
- Overall, it's a very nice blend of the accuracy of high-tension and partial comfort of ELT. 
- I think this is a very good setup. If I go back to normal tensions, I will definitely prefer this method of stringing. In fact, normal tensions where every string is pulled the same poundage has relegated way way behind ELT and full proportional stringing.
- The only downside with this is that spin levels lose out to ELT but is much better than full 60lbs.
- Not much ball fur on the strings after play

- And I don't think the length and width moved much after play too. Maybe 0.5mm? So the stringbed seems stable to me.

Strings:

Pro Supex Synthetic Gut Titan 1.25mm

(Full Proportional Stringing + Box)

Fancy: Wilson Hammer 5.8 + Poly/Syn Gut @ 45lbs

Since stringing my first racket at ELT, I have been testing many different setups to fine tune the tensions. Most played very well.

Recently, there was an opponent who was exceptionally adept at generating spin with power. Maybe I'm a lousy hacker, or the people I hit with play too nice with me. But I have never encountered this levels of spin and power together.

For once, the very heavy ball I had to return challenged the control and stability of the ELT stringbed. Directional control and depth was lacking. Some return of serves kicked off at very odd angles while others sprayed long, left and right, or into the net. Has ELT met its nemesis?

This got me thinking... until I chanced upon Ivan Lendl's very interesting stringing pattern. (link1)(link2) I watched a lot of Lendl's matches when I was young. It is amazing that this idol that I adore, is now again "nudging" me to think out of the box!

This is one way for me to address the lack of control issue with that powerful and spinny shot! Why not?

I plan to use 4 knots with this hybrid. The centre 10 mains are strung with poly first. There is a short side and a long side for this centre mains.

Below pic shows me starting on the 4th cross string.

With flying clamps, a starting pin is necessary.

I'm finishing the crosses. Note I still have the clamp on the main string. This is to let the tension settle-in as I am using different tensions on mains and crosses even with just one poly string.

The poly centre strings have been completed. So I'm filling in the outer mains and crosses with synthetic gut. I am using low-tension proportional stringing on these outer strings to create a soft perimeter. 

The most important step is to plan for blocked holes. You can see me threading the top crosses first before pulling tension.

Here's how the blocked holes looked like. If you look carefully, you can see two red dots on each end of the long white poly string. The red dot marks the change in tension I used from mains to crosses. If the red dot moves, it means tension may have evened out slightly. Several previous experiments have proved that they remain stable after play.

Here's the completed look. I like the white centre with black perimeter.

Playtest:
- After warming up for about 30 min with my ELT stick, I took this out for a spin. (A hard-hitting friend played with it for about 20min to help me break-in the strings)
- The immediate difference, switching from the ELT syn gut, was how stiff this stringbed played. I thought I missed the sweetspot so I tried aiming at different parts of the stringbed - high, low, left and right. Everywhere played stiff and boardy.
- I had to rely on the absence of vibrations to tell if I hit the sweetspot.
- Power level was very low. Compared to ELT syn gut, I had to swing all out to get the ball past the service line.
- Spin was negligible compared to ELT syn gut. Even with a full whip, I could not get the ball to curl in the air nor kick high off the ground. Strangely, the strings felt slippery. Smooth poly maybe?
- I could not feel any pocketing at all.
- With such a stiff bed, directional control was very good indeed. Aiming was easy. However, the lesser amounts of spin (compared to ELT syn gut) affected accuracy for some shots executed under pressure. I still prefer the high-spin setup.
- I'll test this some more later, especially against that chap who gave me problems with his spin and power.

13Jun2013 update:
- This stringbed behaved very well against that big and spinny serving chap. No problems with returns.
- At least this assures me that my service returns are fine. It's soft stringbeds that give me problems.
- Power is still very low. Full swing flat shots barely made it to the other baseline.
- Contact feel is hollow and flat. Not like the plushy synthetic gut feedback.
- One important observation is that the sweetspot moved downwards from the top third to right smack in the middle of the centre poly strings. This is the first time I experienced a sweetspot moving due to stringing and not weight.
- While I cannot say it is uncomfortable, but there is absolutely no doubt at all during play that there is a poly feel to it. Just not that harsh as a pure poly setup.

15Jun2013 update:
- The breaking-in of poly strings seems to take longer than for synthetic gut. I can feel a softening of the poly centre instead of a boardy feel.
- With the softening, power increased slightly together with pocketing.
- Spin levels have also gone up slightly compared to the first two sessions.
- A very good player named "A" tried this racket and commented that the sweetspot is unusually big for a 95 sq in. Control was good. However, off-centre hits feels dead to him. His usual stick is Pro Kennex Ki15 with kevlar/syn gut hybrid strung in the mid 50s.


16Jul2013 update:
- I cannot recall how many hours I've hit with this strings but I can clearly feel the stringbed softened a lot compared to previous sessions.
- Slightly off-centre hits gives a feeling of loss of directional control. The ball would bounce off at a tangent. I think it is due to the softer perimeter which was strung with syn gut that "gives" more than the poly centre.
- Comfort is good, but power, spin and control are seriously lacking.

Strings:
Pro Supex Big Ace Revo 1.25mm

Pro Supex Synthetic Gut Titan 1.25mm