
189 S.E.2d 793 (1972)
STATE of North Carolina
v.
Ada ALTMAN.
No. 728SC478.
Court of Appeals of North Carolina.
July 12, 1972.
Certiorari Denied September 14, 1972.
*794 Atty. Gen. Robert Morgan, by Deputy Atty. Gen. R. Bruce White, Jr., and Asst. Atty. Gen. Guy A. Hamlin, for the State.
Herbert B. Hulse, Goldsboro, for defendant appellant.
Certiorari Denied by Supreme Court September 14, 1972.
CAMPBELL, Judge.
Defendant assigns as error the admission into evidence of the marijuana alleged to have been seized from defendant. Defendant contends that admission of this evidence was error because the affidavit on which the search warrant was based was insufficient and because no voir dire examination was conducted prior to the admission of this evidence.
Defendant argues that the supporting affidavit does not contain sufficient facts to support the issuance of a search warrant.
G.S. § 15-25 provides that a search warrant may be issued by any of the specified judicial officers upon a finding of probable cause for the search. An affidavit indicating the basis for the finding of probable cause must be a part of or attached to the warrant. G.S. § 15-26. An affidavit may be based on hearsay from an undisclosed informant and need not reflect the personal observations of affiant, but the magistrate must be informed of some of the underlying circumstances from which the informant concluded that the narcotics were present and some of the underlying circumstances from which the affiant concluded that the informant was credible and reliable. Aguilar v. Texas, 378 U.S. 108, 84 S.Ct. 1509, 12 L.Ed.2d 723 (1964).
The affidavit in question is based on information given the affiant by an informer *795 and substantiated by the affiant and other members of the Wayne County Sheriff's Department. The affiant stated that an informant had personal knowledge of the delivery of narcotic drugs and marijuana to the residence of defendant at 4:30 p.m. on 24 January 1971. Affiant stated that the Sheriff's Department had observed an unusual amount of traffic in and out of defendant's residence during the preceding year and other reports had been received that defendant was dealing in drugs. This affidavit is specific and detailed. It sets forth substantial underlying facts establishing probable cause for a search. The affidavit must also set forth circumstances from which the officer concluded that his informant was reliable. The affiant stated that the confidential informant, "has proven reliable and credible in the past." We are of the opinion that the circumstances set forth in support of the informant's reliability are the irreducible minimum on which a warrant may be sustained. The statement that the informant has proven reliable in the past is a statement of fact and not a mere conclusion. While we do not approve of such brevity in an affidavit, it does meet the minimum standards. See State v. Moye, 12 N.C.App. 178, 182 S.E.2d 814 (1971).
". . . Although in a particular case it may not be easy to determine when an affidavit demonstrates the existence of probable cause, the resolution of doubtful or marginal cases in this area should be largely determined by the preference to be accorded to warrants. . . ." United States v. Ventresca, 380 U.S. 102, 85 S.Ct. 741, 13 L.Ed. 684.
We hold that this affidavit was sufficient and the search warrant, being adequate in all other respects, was valid.
The defendant assigns as error the failure of the trial court to conduct a voir dire when defendant moved to suppress the evidence obtained under the warrant.
The voir dire is an examination out of the presence of the jury for the purpose of determining some preliminary question of fact. It is purely a procedural device. In ruling on some objections, particularly objections to the introduction of confessions or evidence seized without a warrant, it appears that a voir dire would almost always be necessary. For example, in ruling on the admissibility of a confession, the judge must find whether it was made voluntarily and it would appear that a voir dire is the only method for making such a determination. However, the case before us does not involve such an objection. The defendant has challenged the search warrant on the grounds that the affidavit (which is attached to the warrant) is insufficient. The affidavit and warrant were before the trial court. The sufficiency of the affidavit would appear from the face of the document itself. The affidavit is all that need be examined in order for the judge to rule on the challenge made here. Since all the evidence pertinent to this particular challenge was before the court, there was no need to conduct a voir dire. The trial court examined the affidavit and found it to be sufficient. The judge was asked to rule on a question which could be answered from the face of the affidavit and under these circumstances the defendant could not have been prejudiced by the trial court's failure to conduct a voir dire. We agree that a voir dire is the proper procedure where there is a motion to suppress evidence on the grounds that it is illegally obtained. State v. Myers, 266 N.C. 581, 146 S.E.2d 674 (1966). But it is not required in every case. State v. Eppley & Block, N.C. App., 188 S.E.2d 758 (filed 24 May 1972); State v. Vestal, 278 N.C. 561, 180 S.E.2d 755 (1971).
We emphasize that defendant here has challenged the sufficiency of the affidavit itself, and we confine our decision in this case to that fact.
We hold that, in the circumstances of this case, it was not error for the trial *796 court to rule on defendant's motion without conducting a voir dire.
In this trial we find,
No error.
MALLARD, C. J., and BRITT, J., concur.
