On appeal from his conviction by a District Court jury on three counts of indecent assault and battery on a child under fourteen, the defendant contends that the trial judge erred (i) in failing to conduct individual voir dire of the venire on the subject of child sexual abuse; (ii) in refusing to allow cross-examination into criminal charges pending against the victim at the time of trial; (iii) in failing to instruct the jury on the use of fresh complaint testimony; (iv) in denying his motion for a required finding of not guilty; and (v) in the final instruction to the jury. The defendant also claims that his trial counsel was ineffective in various respects. We affirm the convictions.
Background. The defendant was the victim’s karate instructor at the time of the assaults. In 1999, the police contacted the victim after receiving information that he may have been the victim of a sexual assault. The victim gave a statement to the police describing three occasions on which the defendant fondled him: twice in the victim’s residence while his mother was out, and a third time in the defendant’s residence. Following the third incident, the victim stopped taking karate lessons. According to his mother, that occurred in the spring of 1996. The victim testified at trial about the three incidents; other witnesses included the victim’s mother, the director of the school the victim was attending at the time of the three incidents, and the police officer who took the victim’s statement in 1999.
Voir dire. The defendant claims that a new trial is required because the trial judge did not conduct an individual voir dire *237of potential jurors on the question whether any juror had been a victim of a childhood sexual offense. Trial counsel did not request such a voir dire, an omission the defendant now contends constituted ineffective assistance.
After the jury pool were advised of the charges against the defendant, the judge inquired, inter alla, whether any member of the venire knew of any reason why they “would not be impartial in the case and be able to render a true and just verdict based solely upon the evidence.” The judge did not specifically ask the venire as a group whether the nature of the charges against the defendant would impair their ability to be impartial, and as noted above the judge did not conduct an individual voir dire of the members of the venire to determine whether any had been a victim of childhood sexual abuse and, if so, whether that experience would impair their ability to be impartial.
General Laws c. 234, § 28, requires a trial judge to question prospective jurors individually when it appears that their impartiality may be affected by extraneous issues. A trial judge generally holds wide discretion to determine when individual voir dire is warranted. See Commonwealth v. Grice, 410 Mass. 586, 588 (1991). However, certain types of cases are thought categorically to present sufficiently high potential for extraneous influence that trial judges are required to conduct individual voir dire upon the defendant’s request. See, e.g., Commonwealth v. Sanders, 383 Mass. 637, 640-641 (1981) (interracial rape); Commonwealth v. Hobbs, 385 Mass. 863, 873 (1982) (interracial sexual offenses against children); Commonwealth v. Young, 401 Mass. 390, 398 (1987) (interracial murder); Commonwealth v. Seguin, 421 Mass. 243, 245-249 (1995), cert, denied, 516 U.S. 1180 (1996) (insanity defense). Pertinent to the present matter, the Supreme Judicial Court, in Commonwealth v. Flebotte, 417 Mass. 348, 355 (1994), announced a prospective rule requiring “trial judges on request in future cases to question each potential juror individually as to whether the juror had been a victim of a childhood sexual offense.”
As in each class of cases in which the Supreme Judicial Court has required individual voir dire, the requirement for individual voir dire on the subject of childhood sexual abuse is not grounded in constitutional considerations; it is instead based *238on the general superintendency power of the Supreme Judicial Court to make rules in implementation of the policy set forth in G. L. c. 234, § 28. See Commonwealth v. Holloway, 44 Mass. App. Ct. 469, 473 (1998), and cases cited. As adopted in Flebotte (and, for that matter, in each of the other categories of cases for which individual voir dire is required), the requirement for individual voir dire arises upon the defendant’s request for such inquiry; it is not automatic.1 Because the defendant’s trial counsel did not request an individual voir dire of jurors on the subject of childhood sexual abuse, none were required under the rule announced in Flebotte, and we do not otherwise discern any basis to conclude that the trial judge abused his discretion by failing to conduct such a voir dire sua sponte. There was no error.2
The defendant’s appellate counsel separately contends that trial counsel was ineffective in not requesting individual voir dire, thereby triggering the Flebotte rule. The defendant did not assert such a claim in either of his two posttrial motions for a new trial. Consequently, we do not have before us an affidavit of trial counsel or any other record material to establish that trial counsel did not decline the opportunity for individual voir dire for tactical reasons. Absent support in the record, the defendant’s claim of ineffective assistance is not properly presented for our consideration. See Commonwealth v. McCormick, 48 Mass. App. Ct. 106, 107-109 (1999).
*239Limitation of cross-examination. Prior to trial, the Commonwealth moved in limine to preclude cross-examination of the victim regarding his juvenile criminal record. The judge ruled that the defendant could cross-examine the victim about charges which were pending against him at the time he first implicated the defendant in his statement to police, and which were thereafter dismissed. The judge refused to allow inquiry into new charges pending at the time of trial. As counsel raised no objection to the judge’s ruling at trial, we consider whether any error created a substantial risk of miscarriage of justice.3
The victim’s trial testimony was largely consistent with his initial statement to the police, insofar as it asserted that the defendant had fondled him.4 By cross-examining the victim on the circumstances of his initial statement to the police (the police approached the victim to inquire about the defendant, some three years after the assaults had taken place), the fact that the victim had charges pending against him at the time he gave his statement, and the fact that those pending charges were dismissed a short time thereafter, the defendant was able to impeach the victim in the eyes of the jury, and the defendant forcefully pressed that point in his closing.5 Cf. Commonwealth v. Rodwell, 394 Mass. 694, 700 (1985) (trial judge did not abuse discretion by limiting cumulative cross-examination directed to witness bias). We conclude that the effect of any cross-examination into further charges pending against the victim at the time of trial would have been slight, and that the absence of such inquiry posed no substantial risk of miscarriage of justice.
Fresh complaint. The defendant raises a number of arguments on appeal directed to the admission of the victim’s statement to *240the police. The defendant first argues that the statement was inadmissible hearsay which should not have been admitted at all. Alternatively, the defendant contends, the statement was admissible only as a fresh complaint and should accordingly have been limited by appropriate instruction. Though trial counsel made no objection to the testimony, and did not request a limiting instruction, the defendant on appeal contends that trial counsel was ineffective in that respect.
We agree with the defendant that the victim’s statement to the police was not admissible as fresh complaint,6 but conclude that trial counsel chose for tactical reasons not to object to the testimony. Specifically, the defendant sought to impeach the victim’s credibility by use of the charges pending against the victim at the time of his statement to the police, and by pointing out inconsistent details between the victim’s statement to the police and his trial testimony.7 Such circumstances form no basis for a new trial on grounds of ineffective assistance of counsel or a substantial risk of miscarriage of justice. See Commonwealth v. Fanara, 47 Mass. App. Ct. 560, 566-567 (1999).
Motion for required finding. The defendant cites conflicting and occasionally ambiguous testimony on the date of the assaults to claim that the evidence was insufficient to establish that the victim was under the age of fourteen when the assaults occurred. The victim turned fourteen on December 27, 1996. The assaults occurred while the victim was taking karate lessons from the defendant. The victim’s mother testified that the victim started taking karate classes “in the winter of ‘96” and continued “[ujntil the spring of that year, late spring.” On cross-examination, when the defendant’s trial counsel asked her if the victim “stopped taking karate sometime in the spring of 1997,” the mother responded, “No, excuse me, I meant — like *241right around January, December of — started in ‘95, the winter of ‘95, I made a mistake on that because he stopped in the spring of ‘96.” Considered in the light most favorable to the Commonwealth, see Commonwealth v. Latimore, 378 Mass. 671, 677 (1979), that evidence formed a sufficient basis for the jury to conclude that the assaults occurred before the victim turned fourteen in December, 1996.8
Jury instruction. During his final charge to the jury, the judge instructed jurors that “[yjou may believe everything a witness says or only part of it, or none of it at all. If you do not believe a witness’s testimony that something happened, your disbelief is not evidence that it did not happen. When you disbelieve a witness it just means that you have to look elsewhere for credible evidence about that issue.” We reject the defendant’s argument that the judge’s instruction invited the jury to find the defendant guilty even if they disbelieved the witnesses. Instead, we conclude that the instruction, though perhaps inartful, merely advised the jurors, correctly, that disbelief of a witness’s testimony does not constitute evidence of the contrary proposition. See Commonwealth v. Michaud, 389 Mass. 491, 498 (1983); Commonwealth v. Camerano, 42 Mass. App. Ct. 363, 367 (1997).
Ineffective assistance of counsel. We have addressed above the defendant’s claims of ineffective assistance of trial counsel arising from counsel’s failure to request individual voir dire, and from his failure to object to (or request an instruction limiting) the hearsay testimony recounting the victim’s statement to the police. The defendant has not demonstrated that any inquiry into the victim’s confidential medical and counseling records would have produced any material that would have assisted his defense; absent such a showing it is speculative to assert that trial counsel’s failure to seek such records “deprived the *242defendant of an otherwise available, substantial ground of defence.” Commonwealth v. Swan, 38 Mass. App. Ct. 539, 541 (1995), quoting from Commonwealth v. Saferian, 366 Mass. 89, 96 (1974). As to the defendant’s argument that trial counsel was ineffective for failing to object to testimony that the defendant “liked to like the kids a little bit, like hug them, like have them sit on his lap and stuff,” we conclude that the prejudicial effect of the testimony, if any, was sufficiently slight that it did not create a substantial risk of miscarriage of justice.
Judgments affirmed.